Re: [time-nuts] Terminators on empty outputs/connectors

[Graham / KE9H]

As usual, the answer is "it depends."

If the output is a single isolated output, then terminating load not
required, but no harm providing.

If the output is a multiple output, from a single driver, through a
resistive or transformer splitter, then the level stability on all ports
and the port to port isolation is dependent on the proper termination of
all ports.
So, if multiple 10 MHz or 1 pps outputs, terminations highly recommended.

--- Graham

==

On Fri, May 25, 2018 at 10:21 AM, Dana Whitlow 
wrote:

> I recommend putting terminators on unused ports, on general principles.
> But I don't
> think it would ordinarily be necessary to use big-bucks terms, unless the
> distro amp is
> really cheaply made.
>
> If you have access to a VNA, it would be interesting to measure the complex
> transmission
> coefficient from input to one of the output ports while experimenting with
> variations of
> the number and locations of terminations for the other output ports.  If
> you find that none
> of such manipulations have any visible effect, then you can probably skip
> using terms
> on unused ports.  I should mention that any such measurements should best
> be performed
> at roughly the intended operating RF power level.
>
> And for extra credit, report your findings to this discussion group.
>
> Dana
>
>
> On Thu, May 24, 2018 at 3:41 AM, Clay Autery  wrote:
>
> > Putting in a hardware order...
> >
> > Question:  Is it recommended to put terminators on all unused GPS Distro
> > amp ports?  Output ports on GPSDO and NTP servers (10MHz and PPS).
> >
> > Thanks!
> >
> > --
> > __
> > Clay Autery
> > MONTAC Enterprises
> > (318) 518-1389
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
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Re: [time-nuts] suggestions on getting 24 Mhz ?

[Graham / KE9H]

Phase noise is (usually) more important than absolute frequency accuracy.

I suggest some kind of low phase noise master oscillator (OCXO) feeding a
DDS without an internal multiplier.

If internal multiplier in DDS, that, rather than the frequency reference
source will set the phase noise floor of the sampling.

--- Graham

==

On Wed, Apr 11, 2018 at 11:00 AM, Jerry Hancock  wrote:

> For and RSP?  I used an HP 3325 locked to my Cs beam and took the signal
> from the back.  I think I paid no more than $100 for the 3325a and one I
> got for free.
>
> Regards,
>
> Jerry
>
>
> > On Apr 11, 2018, at 4:49 AM, jster...@att.net wrote:
> >
> > Leo Bodnar GPSDO - adjustable Low-jitter GPS-locked precision frequency
> reference 400 Hz to 810 MHz .  He has a new one, single output for 99
> british pounds.
> >
> > Jerry NY2KW
> >
> > -Original Message-
> > From: time-nuts  On Behalf Of Pete
> Lancashire
> > Sent: Wednesday, April 11, 2018 6:00 AM
> > To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
> > Subject: [time-nuts] suggestions on getting 24 Mhz ?
> >
> > Needed for SDR project as external clock source.
> >
> > -pete
> > ___
> > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >
> > ---
> > This email has been checked for viruses by Avast antivirus software.
> > https://www.avast.com/antivirus
> >
> > ___
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Re: [time-nuts] WWVB Time

[Graham / KE9H]

Did you move it near a desktop PC or other computer, or move a desktop, or
other PC, video screen or switching power supply in the vicinity of the
Symmetricom or WWVB antenna?

I am learning the hard way that PC and LED/LCD video screens are horrible
generators of noise in the LF spectrum.

--- Graham

==

On Tue, Apr 10, 2018 at 4:15 PM, Tom Van Baak  wrote:

> > Hi, all of a sudden my Symmetricom comparator/clock has been locking up
> on time.
> > It has been about a week so far. Did they change the code? Anyone else
> seeing that?
> > Doug K6JEY
>
> Hi Doug,
>
> That would be too good to be true. I asked NIST just now and they report:
> "We have not changed the code or power level. All things remain the same."
>
> So let's debug this on your end.
> - What make/model WWVB receiver are you using?
> - Can you check the accuracy of the time or frequency output against GPS /
> GPSDO. Is it NIST accurate or a bad copy of 60 kHz?
> - Did you power-up any new instrument in the past week, one that might
> cause 60 kHz harmonics?
> - Can you check with 'scope or spectrum analyzer what your environment
> looks like near 60 kHz?
> - Do you have a curious neighbor who is experimenting with a WWVB
> simulator...
>
> /tvb
>
> - Original Message -
> From: "Doug Millar via time-nuts" 
> To: 
> Sent: Tuesday, April 10, 2018 1:23 PM
> Subject: [time-nuts] WWVB Time
>
>
> Hi, all of a sudden my Symmetricom comparator/clock has been locking up on
> time. It has been about a week so far. Did they change the code? Anyone
> else seeing that? Doug K6JEY
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Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

[Graham / KE9H]

 > The Chinese have no concept of, or ignore, intellectual property rights.

Do not forget that China is a communist government and culture..
And has been since about 1948.
So no one left who was raised under a different system of government.
Under communism, every thing is owned by "the people."
If people can't individually own land or property, how could they possibly
own something like an idea?
It is a fundamentally incomprehensible concept.
So they don't think they are doing something wrong when use someone else's
idea, or software, or design.

But they have figured out that their foreign customers get all upset when
they do re-use their ideas and designs.

So the government is making "adjustments" so that they can fit in with the
rest of the world, but only recently.

Enough off-topic, sorry.

--- Graham

==

On Thu, Feb 22, 2018 at 9:42 PM, Ruslan Nabioullin 
wrote:

> On Thu, Feb 22, 2018 at 5:48 PM, djl  wrote:
> > Fine. The Chinese have no concept of, or ignore, intellectual property
> > rights.
>
> Which is not necessarily perverse---there exist people (most notably
> those of the so-called Pirate Party movements worldwide) who deem the
> legal theories of the copyright and the patent to be absurd.  That is
> all that I will say, for I do not wish to excessively deviate from the
> topic of discourse.
>
> -Ruslan
>
> --
> Ruslan Nabioullin
> Wittgenstein Laboratories
> rnabioul...@gmail.com
> (508) 523-8535
> 50 Louise Dr.
> Hollis, NH 03049
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Re: [time-nuts] "Confessions of a Reformed Frequency Standard Nut"

[Graham / KE9H]

And if I do some longer term averaging, I can get another one after that.
 :-)

--- Graham

==

On Fri, Jan 19, 2018 at 11:16 AM, Ron Bean 
wrote:

> https://hackaday.com/2018/01/17/confessions-of-a-reformed-
> frequency-standard-nut/
>
> "Or are you chasing that last digit just because it’s there?"
>
> ___
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Re: [time-nuts] minimalist sine to square

[Graham / KE9H]

SN65LVDS34D

--- Graham / KE9H

==

On Fri, Jan 19, 2018 at 3:45 PM, Vlad <t...@patoka.org> wrote:

>
>
> On 2018-01-19 14:31, Tom Van Baak wrote:
>
>> John's TADD-2-mini [1] uses the Wenzel sine-to-square converter. It
>> performs very well but requires +10 V.
>>
>
>
> I am using Wenzel approach without modification to drive it from +5V. I
> didn't see any issues for my applications (usually it perform
> sine-to-square conversion from OCXO to feed MCU clock).
>
>
> --
> WBW,
>
> V.P.
>
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Re: [time-nuts] Weird GPSDO behavior

[Graham / KE9H]

Could be a delivery truck with a GPS jammer on it, that passes your
location every morning at the same time.

--- Graham

==

On Fri, Sep 29, 2017 at 7:18 AM, Bob kb8tq  wrote:

> Hi
>
>
> > On Sep 28, 2017, at 6:59 PM, Mark Sims  wrote:
> >
> > I suspect that it is either temperature related (the funkiness starts
> around when the temperature reaches a minimum) or related to the way the
> disciplining parameters are hacked to get the extended time constant.
>
> Like it or not, most of these devices were made back a while ago.
> The CPU’s used were not the ones we have today. the code was tested
> over the “expected range” of values. Most (but not all) of the control loop
> code was done as integer math. With limited RAM, tossing everything into
> 64 or 128 bit integers was not an option. In some cases 32 bit int’s were
> at
> a premium. Multiply this by that, that, and that. Then divide by
> something, and
> something else. … hmmm…. a few bits just went missing. Could you reorder
> and fiddle to fix some of this? Sure, that’s where we get back to the
> expected
> range stuff.
>
> Even if it’s not in the “main loop”, GPSDO code is full of checks for this
> or that.
> Like the main math, they are scaled and tested for the normal range of
> parameters.
> Not all of them spurt error messages when they get involved. Some just
> bump this
> or that and move on.
>
> Lots of possibilities ….
>
> Bob
>
>
>
> > Try setting up for say a 10,000 second time constant and see how things
> change.
> > ___
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Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Graham / KE9H]

Remember the military drone that the Iranians tricked into landing in Iran
a few years ago?

The best explanation I heard of how they did it was that they knew that if
it lost its command channel, that it would return to the airport where it
took off.

So, what they did was spoof the GPS with a signal that said it was 150
miles further east than it actually was, then jam the control channel, and
it set down nicely on the airport it came from, except that it was the
desert in IRAN with a few rocks that ripped up its landing gear, and not
its home runway.

Would this spoof be as easy as recording the real signal and playing it
back (louder) delayed by about 120 seconds? (Assuming you want to shift
things to the East.) (Also assume you have a relatively unsophisticated GPS
nav receiver.)

--- Graham

==

On Mon, Aug 14, 2017 at 1:41 PM, Bob kb8tq  wrote:

> Hi
>
> > On Aug 14, 2017, at 2:13 PM, Chris Albertson 
> wrote:
> >
> > The trouble with spoofing location is that in theory every ship is using
> > more than one method of navigation.   They would notice their GPS is
> acting
> > up and turn it off.
>
> In most cases the “other method” is dead reckoning. That’s actually being
> generous. There are a *lot* of cases every year where the answer is that
> the vessel is on GPS autopilot with nobody at all on watch. Yes the
> results of
> breaking the law are fairly predictable. Actually having a competent
> navigator
> on duty all the time running “alternate” data, that costs money …..
>
> Bob
>
> >
> > I'm far from a professional but I've taken the  six week class and I'm
> > reasonably certain I could find a place on the other side of the pacific
> > ocean with no GPS.   The GPS is far easier to use and more accurate but
> no
> > one uses just GPS alone, they alway compare several methods.
> >
> > On Mon, Aug 14, 2017 at 10:12 AM, Clint Jay  wrote:
> >
> >> I guess it would depend on the level of infrastructure available to the
> >> attacker, clock distribution is a reasonably well solved problem isn't
> it?
> >>
> >> There would, I suppose also be the issue of receiver swamping, you could
> >> monitor received signal levels as it's my understanding that the signals
> >> from the satellites are weak enough that they're indiscernible from
> noise
> >> floor without some rather complex processing?
> >>
> >> Authentication via signing could be another feasible way to prevent
> >> spoofing except we are potentially talking about interference from state
> >> actors who may even be the very people who run one of the satellite
> >> networks
> >>
> >> On 14 Aug 2017 5:51 pm, "Attila Kinali"  wrote:
> >>
> >>> On Mon, 14 Aug 2017 12:09:43 -0400
> >>> Tim Shoppa  wrote:
> >>>
>  I think if you are only trying to spoof a single receiver it would be
>  possible to walk a spoofed time/space code in a way that time moved
> >>> without
>  so obvious of a discontinuity. I'm sure there would be effects a
> >> time-nut
>  could notice still.
> >>>
> >>> Not really. Unless you have a multi-antenna setup (see jim's email),
> >>> you have nothing to compare the signal to. Even an ideal reference
> >>> clock in your GPS receiver does not help, as the attacker could be
> >>> tracking you in such a way that you will never see a discontinuity
> >>> in time or position and that all the other sanity checks you do
> >>> still don't show anything.
> >>>
> >>> With a two antenna setup, you can already check whether the phases
> >>> add up to what you expect them to be, given your position relative
> >>> to the satellites position. You do not need 3 antennas as a potential
> >>> attacker can spoof the phase of some satellites correctly, but not
> >>> of all at the same time. This at least gives you a spoof/no-spoof
> signal.
> >>>
> >>> With an antenna array you can do some masking of spoofers (ie placing
> >>> a null where the spoofer comes from). But this increases the cost and
> >>> complexity of the system super-linear with the number of antennas.
> >>> Maybe one way to do it, would be to use a single receiver with a stable
> >>> reference clock and switch between antennas in short succession. Ie
> >> similar
> >>> to how the early single channel GPS receivers worked, but for antennas
> >>> instead of SVs. But I have no idea how easy/difficult this would be
> >>> to do and how well it would work against spoofers.
> >>>
> >>>Attila Kinali
> >>> --
> >>> It is upon moral qualities that a society is ultimately founded. All
> >>> the prosperity and technological sophistication in the world is of no
> >>> use without that foundation.
> >>> -- Miss Matheson, The Diamond Age, Neil Stephenson
> >>> ___
> >>> time-nuts mailing list -- time-nuts@febo.com
> >>> To unsubscribe, go to https://www.febo.com/cgi-bin/
> >>> 

Re: [time-nuts] Thunderbolt - trouble locking with some types of antennas

[Graham / KE9H]

Dider:

This is a CDMA signal. (With a 'chip' rate that far exceeds the information
rate.)

If you put a different correlator on every multipath signal, which are each
differently delayed in time, then they can be independently demodulated.
(Or time shifted and added back together with some quality indicator for
weighting.)
So, in CDMA, multipath is used as a form of (time) diversity reception and
will improve the signal to noise of the combined signal.

By definition, the signal with the least time delay either is, or is
closest to, the most direct path.

You don't have to necessarily fully demodulate this early signal by itself,
just know what its timing is. (And remember where it was, if fading in and
out.)

Since multi-path is a destructive mechanism in most narrow band radio
systems, the above may not be intuitive to people not familiar with CDMA
and "rake receiver" based systems.

Multipath helps, not hurts, these systems, as long as the multipath delays
are most of one chip apart, or more.

--- Graham

On Tue, Aug 1, 2017 at 1:11 PM, Didier Juges  wrote:

> "The newer the receiver, the more horsepower in the silicon. In the case of
> GPS, that
> gives you more correlators to do DSP. The sensitivity improvement is a
> direct result
> of that. If you take a look at the guts of a TBolt, they date to the late
> 1990’s. That’s
> a long time in silicon years …."
>
> It seems that more correlators would speed up the time to first fix, not
> necessarily the sensitivity, particularly I do not see how it would
> directly affect the capability to stay locked when signal strength
> fluctuates?
> On the other hand, more correlators may help when there is multipath and a
> whole bunch of extraneous signals are fed into the receiver, so maybe the
> apparent lack of sensitivity is really the inability to see the signal from
> the chaff, not necessarily sensitivity in terms of noise figure.
>
>
> On Mon, Jul 31, 2017 at 3:06 PM, Bob kb8tq  wrote:
>
> > Hi
> >
> > > On Jul 31, 2017, at 3:32 PM, Didier Juges  wrote:
> > >
> > > The Thunderbolt is well known for not having the best sensitivity among
> > GPS
> > > receivers. It seems that timing receivers in general, particularly
> those
> > of
> > > the same generation as the Thunderbolt are not as sensitive as
> navigation
> > > (possibly newer) GPS receivers. It may be because they are expected to
> > run
> > > with amplified antennas?
> >
> > The newer the receiver, the more horsepower in the silicon. In the case
> of
> > GPS, that
> > gives you more correlators to do DSP. The sensitivity improvement is a
> > direct result
> > of that. If you take a look at the guts of a TBolt, they date to the late
> > 1990’s. That’s
> > a long time in silicon years ….
> >
> > Bob
> >
> >
> > >
> > > Based on the spec you wrote, it looks like your antenna has no gain, so
> > > definitely I would expect less than good performance.
> > >
> > > My 3 Thunderbolts have been running with inside antennas (2 pucks and
> one
> > > Trimble Bullet) but my ham shack is upstairs and other than the ceiling
> > and
> > > the shingle roof, there are no other obstructions and they are doing OK
> > not
> > > great (all 3 go on holdover somewhat regularly). I am now running one
> > > downstairs (while I work on the new software for the TB Monitor) with
> 50
> > > feet of RG-58 going to a HP 58532A antenna somewhat in the clear but
> > only 8
> > > feet above ground with significant obstructions in pretty much all
> > > directions due to the low height and the Thunderbolt is happy as a clam
> > in
> > > spite of the significant losses in the cable. The HP antenna works much
> > > better than the Trimble Bullet antenna.
> > >
> > > On Mon, Jul 31, 2017 at 12:19 PM, Jerry  wrote:
> > >
> > >> Due to access problems, I run my Thunderbolt with a Symmetricom 58532A
> > >> antenna placed indoor near a window facing South… can’t get much worse
> > but
> > >> most of the time it will be locked onto 3 or 4 satellites.I
> recently
> > >> bought a www.leobodnar.com   GPSDO for my
> SDR
> > >> ham
> > >> radio setup.  I was very surprised to find that this minimalist GPSDO
> > using
> > >> a small patch antenna with internal LNA placed near my window had
> > satellite
> > >> & PPL lock within a few seconds.  It requires 3-4 satellite locks for
> > its
> > >> PPL.  However, when I attached the patch antenna to my Thunderbolt –
> > >> satellite signal strength were zero or minus for all satellites.  The
> > specs
> > >> for the patch antenna are listed below.
> > >>
> > >>
> > >>
> > >> I would appreciate any advice understanding this behavior.
> > >>
> > >>
> > >>
> > >> Jerry NY2KW
> > >>
> > >>
> > >>
> > >> Center Frequency 1575.42MHz±3 MHz
> > >>
> > >> V.S.W.R 1.5:1
> > >>
> > >> Band Width ±5 MHz
> > >>
> > >> Impendence 50 ohm
> > >>
> > >> Peak Gain >3dBic Based on 7×7cm ground plane
> > >>
> > >> Gain 

Re: [time-nuts] A look inside the DS3231

[Graham / KE9H]

The typical method of frequency correction is not to add or subtract
capacitance across the crystal, (like an old analog engineer would do) but
rather to add or subtract pulses to the stream of cycles/pulses coming out
of the crystal oscillator. More the kind of correction a digital engineer
would do.  The long term end result is correct, but the addition and
subtraction of correction pulses shows up as jitter and short term errors.

As far as the need for low battery drain, everything is going for smaller,
lighter, cheaper, portable, and runs off a battery.  You would probably
turn your nose up at a watch, whose battery did not last at least a year.
Most simple watches go several years.  Now put an electronic display on it,
and a GPS in it and BlueTooth LE.  Everything inside is under pressure to
make sure the battery lasts as long as possible.

I personally don't wear a watch any more. Get GPS time from my cellphone,
that fits in my watch pocket of my jeans.  (I finally found a use for that
pocket, after wearing pants with them for 50+ years.)

But, I have to charge the thing every day, every other day, at the most.

What I want, is a cellphone that I only have to charge once a week, or once
a month.

I don't want to have to be in the battery management business.

Before we exited from the pager business, we had a customer that had a
published goal of a pager that would run an entire year on one "AA" primary
(alkaline throw-away) battery.  Imagine changing the battery once per year,
on New Years day. We were up to running for nine months from a single AA
battery.  Now, that was a radio receiver and a 'beeper' (and an internal
clock for management purposes.).  And we had a road map to get to the full
year, but the cellphone systems killed the pager business first. It was all
about timing, and putting as much of the IC to sleep at any given time, as
you could.

On Sun, Jul 30, 2017 at 8:37 AM, Mark Sims  wrote:

> A friend of mine is an engineer for one of the biggest manufacturers  of
> clock chips and has worked quite a bit on their clock chips and is quite
> familiar with the issues of building consistent ultra low power oscillators
> in a production product.   Getting nanowatt (and now sub-nanowatt) level
> oscillators to do their thing consistently is not easy.   Getting them to
> do it with customer supplied crystals is a big thing.   Variations by the
> crystal maker regularly cause previously working products to stop working.
> Also they are notoriously sensitive to PCB layout issues.  Older, higher
> power clock chips don't have nearly as many problems as the newer ultra low
> power designs.   Competition to see who can make the lowest power clock
> chips seems to be one of the biggest drivers for new clock chip designs.
>
> Oh, and although the clock chip oscillators have good long term accuracy
> they tend to have lots of jitter and poor ADEVs.
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Re: [time-nuts] A look inside the DS3231

[Graham / KE9H]

Yes, I doubt that the volume on a specialty chip like the DS3231 is high
enough to attract the counterfeiters.

RS-232 chips and the FTDI USB to serial chips, and consumer FM tuner and
audio amplifier chips, is another story.

My experience was with a proprietary full custom IC that totally
implemented a 'pager' in a single IC package. The Chinese apparently wanted
to get into the the paging business, at the time.  Of course, the
cellphones have now totally eaten the pager business, globally.

--- Graham

==

On Thu, Jul 27, 2017 at 8:21 PM, Pete Stephenson <p...@heypete.com> wrote:

> Graham,
>
> That's very true!
>
> Still, my past experience with copied chips typically involves a
> particular type of RS-232-to-TTL serial converter, the MAX3232. I've
> found that nearly all of the ones from unauthorized distributors (e.g.
> auction site vendors) are fake, even though the package is marked as
> being MAX3232. After a few weeks the chips would fail in a way that
> they'd pass high currents and get extremely hot.
>
> I did a write-up on those chips at
> <https://blog.heypete.com/2016/09/11/investigating-fake-
> max3232-ttl-to-rs-232-chips/>
> and, after decapuslating them, discovered they were completely different
> chips on the inside that were made to function the same way as the
> MAX3232 (i.e., they converted RS-232 signals to TTL serial, operated on
> the same voltages, had the same pinout, etc.).
>
> In regards to the DS3231, I was concerned that the chip was also a fake
> that functioned in the same way as the DS3231, presented the same
> registers to the user, etc., but was actually a different design on the
> inside. It appears that this is not the case, and in addition to
> functioning as advertised, it also is legitimate. If it is a clone, it's
> a goood one, but I don't think it is.
>
> Cheers!
> -Pete
>
> --
> Pete Stephenson
>
> On Thu, Jul 27, 2017, at 10:34 PM, Graham / KE9H wrote:
> > Pete:
> >
> > If you are concerned about someone copying a chip, you can not rely on
> > the
> > original manufacturers' markings on the die.
> >
> > I have experience where the counterfeiter just photocopied the chip
> > layout,
> > including the original manufacturers marks, and copyright symbol and
> > notice
> > from the original die.
> >
> > So, when they copied the die, they really just copied it. Didn't change a
> > thing. It was not like they redesigned it, or were selling their own
> > design
> > with equivalent functionality.
> >
> > --- Graham / KE9H
> >
> > ==
> >
> >
> >
> > On Thu, Jul 27, 2017 at 2:31 PM, Pete Stephenson <p...@heypete.com>
> > wrote:
> >
> > > Hi all,
> > >
> > > A few days ago I reported the results from letting a DS3231 RTC run for
> > > a year, and how the chip kept time well within the published specs.
> > >
> > > Since I had acquired several DS3231s from dubious sources (Asian
> vendors
> > > on a major auction site) as part of an RTC module that fits on the
> > > Raspberry Pi's header pins, I was doubtful of the authenticity of the
> > > chips. I decided to sacrifice one in the name of science and decapped
> it
> > > at home using alternating heat (a lighter) and cold (a glass of cold
> > > water) to embrittle the epoxy casing, then sanded down the back of the
> > > chip on fine-grain sandpaper to expose what I hoped was the back of the
> > > internals (so as not to damage the die itself).
> > >
> > > Other than inadvertently sanding through half of the crystal's housing,
> > > thus breaking one of the forks of the crystal, this was a success. (I
> > > was prepared to decap one in acid had my attempt at physically removing
> > > the epoxy package failed.) I slightly scratched the die itself while
> > > separating it from the epoxy, but the die itself is clearly visible.
> > > Based on a sample size of one and the markings on the die itself, it
> > > appears the chip is authentic. The markings on the outside of the epoxy
> > > package look a bit dubious and not like typical Maxim laser-markings,
> so
> > > it's possible the chip was re-labeled at some point. I'll contact Maxim
> > > to see if they can look up the lot information.
> > >
> > > I used my 2 megapixel USB microscope to take some images throughout the
> > > process that you might find interesting. The microscope has limited
> > > resolution, particularly at high magnification, so some of the photos
> > > may not be perfectly clear. I have access to a Zeiss petrographic
> >

Re: [time-nuts] A look inside the DS3231

[Graham / KE9H]

Pete:

If you are concerned about someone copying a chip, you can not rely on the
original manufacturers' markings on the die.

I have experience where the counterfeiter just photocopied the chip layout,
including the original manufacturers marks, and copyright symbol and notice
from the original die.

So, when they copied the die, they really just copied it. Didn't change a
thing. It was not like they redesigned it, or were selling their own design
with equivalent functionality.

--- Graham / KE9H

==



On Thu, Jul 27, 2017 at 2:31 PM, Pete Stephenson <p...@heypete.com> wrote:

> Hi all,
>
> A few days ago I reported the results from letting a DS3231 RTC run for
> a year, and how the chip kept time well within the published specs.
>
> Since I had acquired several DS3231s from dubious sources (Asian vendors
> on a major auction site) as part of an RTC module that fits on the
> Raspberry Pi's header pins, I was doubtful of the authenticity of the
> chips. I decided to sacrifice one in the name of science and decapped it
> at home using alternating heat (a lighter) and cold (a glass of cold
> water) to embrittle the epoxy casing, then sanded down the back of the
> chip on fine-grain sandpaper to expose what I hoped was the back of the
> internals (so as not to damage the die itself).
>
> Other than inadvertently sanding through half of the crystal's housing,
> thus breaking one of the forks of the crystal, this was a success. (I
> was prepared to decap one in acid had my attempt at physically removing
> the epoxy package failed.) I slightly scratched the die itself while
> separating it from the epoxy, but the die itself is clearly visible.
> Based on a sample size of one and the markings on the die itself, it
> appears the chip is authentic. The markings on the outside of the epoxy
> package look a bit dubious and not like typical Maxim laser-markings, so
> it's possible the chip was re-labeled at some point. I'll contact Maxim
> to see if they can look up the lot information.
>
> I used my 2 megapixel USB microscope to take some images throughout the
> process that you might find interesting. The microscope has limited
> resolution, particularly at high magnification, so some of the photos
> may not be perfectly clear. I have access to a Zeiss petrographic
> microscope at my work and will see if I can get some better images
> tomorrow. I'll try to get high-quality images of the whole chip and
> stitch them together into a larger composite.
>
> Anyway, the photos are available at http://imgur.com/a/0zudj -- I will
> add more photos from the petrographic microscope tomorrow. I focused
> mainly on the markings on the die that indicated it was, in fact, a
> Maxim chip but if there's any other region of the chip that you'd like
> images of, please let me know and I'd be happy to take some more
> pictures.
>
> I hope you find this as interesting as I did.
>
> Cheers!
> -Pete
>
> --
> Pete Stephenson
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Re: [time-nuts] Hints on PPS Buffer design...

[Graham / KE9H]

Read the spec sheet on the part you are using for a driver.
The size of the resistor on the paralleled driver side will be set by the
maximum current of the devices.

Decide how conservative a design you want.
Do you want it to drive into a shorted load and survive?
[If each output is rated at 20 mA, in a 5 Volt system, then R=E/I, = 250
Ohms]

Or do you only want it to work into a 50 Ohm load (to ground)?

Or perhaps only a Thevenin load? 50 Ohm load, but 100 Ohms up to +V, and
100 Ohms to ground.

Remember that 50 Ohms in a 5 Volt system will draw 100 mA on the 'High'
which can be a lot of current
for a modern IC.

--- Graham

==

On Sat, Jun 17, 2017 at 4:01 AM, Hal Murray  wrote:

>
> caut...@montac.com said:
> > Q3: It's only a 1Hz frequency, but is low inductance a desired trait of
> the
> > chosen resistors?
>
> It's a 1 Hz repetition rate, but the bandwidth depends upon the rise time.
> If the rise time is ballpark of 1 ns, the bandwidth will be ballpark of 1
> GHz.  So, yes, you want low inductance.  That includes the power to the
> chip
> as well as the resistors.  Surface mount is your friend.  So are
> ground/power
> planes.
>
> How good is your scope?
>
>
> > Q:  Why does everyone pick FIVE x 100 Ohm resistors?  That's 20 Ohm out,
> not
> > counting the gate impedance on the hex inverter...
>
> The FIVE is 6-1.  The one is for isolation.  The 5 is the rest of the
> package.  You might as well use them all as drivers.  You don't want to use
> them for another signal (even if it is supposed to be identical) or you
> will
> get minor crosstalk when you do things like plug or unplug a cable.
>
> I don't know why you are saying "gate impedance".  That's over on the input
> side.  I would have said "output impedance" or "driver impedance" of the
> chip
> or section.
>
> I'm not sure why they picked 100 ohms.  Assume the net source impedance is
> 25
> ohms.  Suppose the far end is terminated with 50 ohms.  There won't be any
> reflections so the source value doesn't matter.  25 ohms will provide a
> higher voltage at the far end than 50.  If you have a CMOS driver and a
> CMOS
> receiver, 1/2 the voltage at the receiver is nasty.  It might be OK if you
> have HT type receivers.
>
> I would suggest a bit of lab work.  What are you going to use on the far
> end?
>
> Lots of gear has 1000 ohms rather than 50 so a 50 ohm source impedance
> takes
> care of the reflections and leaves (almost) the full voltage at the
> receiver.
>
>
> caut...@montac.com said:
> > thus I can only include that I need to use something slightly more than
> 250
> > Ohms on a 5 gate parallel setup)
>
> More than 250 divided by 5 and rounded up a bit for the output impedance of
> the chip will be more than 50 ohms.  I'd do some experiments.
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] TruePosition on the Arduino

[Graham / KE9H]

Ben:

Be careful.

Most GPS receivers send out the serial message after the tick, that tells
you what the time of the tick was.

Read the manual.

If you want to drive a clock display with a GPS, you pretty much have to
have an independent time system that advances on the tick, then validate it
when the serial message shows up.

--- Graham / KE9H

==

On Tue, Jun 6, 2017 at 6:46 PM, Ben Hall <kd5...@gmail.com> wrote:

> Good evening all,
>
> There is a saying: "a man with one watch knows the time, a man with two is
> never sure."  Clearly, this man wasn't a timenut and didn't have GPS.  ;)
>
> I've been working on the Arduino code for the TruePosition boards that
> quite a few of us have bought from the e-place.
>
> It's my first real foray into both Arduino and the C language.  (About a
> million years ago I was reasonably competent with FORTRAN...the 1977
> version...)  It's mostly working - I can receive and display pretty much
> everything that comes out of the unit minus a few parameters.  I can
> display it all on three pages on a 4 line by 20 character I2C display.
> Currently, the pages are selected by grounding out one of two pins, or
> having nothing grounded.  Eventually, I'm going to change this so that it
> changes display pages when a button is pressed.  I don't have lat/long
> display yet, nor can I handle doing a survey, but those are coming.
>
> My code probably would make a real programmer vomit, but hey, it works.  :)
>
> Back to the man with multiple watches.  I was having a very frustrating
> issue with my TruePosition and Arduino code being one second behind my
> other sources of time.  I went round and round, trying to figure out why
> the TruePosition thru the Arduino was a second slow.  In the end, it turns
> out that it wasn't slow...it was correct...but that my other sources of
> time have errors.
>
> I finally proved this to myself by firing up an old Trimble Lassen LP GPS
> board unit equipped with a 1PPS tick light and serial output...and it was
> clear that it matched the TruePosition after correcting for the fact that
> my TruePosition / Arduino code only updates the display when 1PPS is
> asserted high...but that the Lassen LP displays the serial message before
> it becomes valid at the next 1PPS tick.
>
> I was slightly embarrassed...I should have known that the other sources of
> time all had sources of error beyond my control.  I should have trusted the
> TruePosition as being the purest, least complicated, and the path I knew
> the most about between GPS and my eyeballs.
>
> So for a while...the statement was true.  With my multiple sources of
> time...I really didn't know the time.  But it was also untrue, as when I
> got agreement between two very "pure" sources of time, I knew everything
> else was wrong.  ;)
>
> I'm getting to the point that once I've got the button logic working, I'll
> send out my source to anyone who wants to take a look at it or use it.  I
> will stipulate one condition - you can't make too much fun of how poorly
> programmed it is.  ;)
>
> thanks much and 73,
> ben, kd5byb
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Re: [time-nuts] Time-nut going England!

[Graham / KE9H]

If you have never seen them, you must make a pilgrimage to see the Harrison
Clocks at the Greenwich Observatory.

If you have not read the book, you must read the book "Longitude" before
seeing the clocks.

--- Graham

On Wed, Apr 26, 2017 at 8:05 AM, Attila Kinali  wrote:

> Hi
>
> I'll be in the UK for three weeks and will have a "free" week
> between 13th and 20th of May. I will most probably be around
> the London area and maybe spend a day or two in Southampton.
>
> If someone wants to meet for a beer or cup of hot chocolate,
> or knows of time-nutty things to do, please let me know.
>
> I would also appreciate if someone knows an affordable place
> to stay at in London, so that it doesn't strain the purse
> of this poor student too much.
>
> Attila Kinali
>
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] RFDO - Experience and questions

[Graham / KE9H]

Anders:

What antenna are you using that you call the "mini-whip?"

Specifically, how long is the "whip?"

Thanks,
--- Graham

==

On Mon, Mar 6, 2017 at 3:57 AM, Anders Wallin 
wrote:

> FWIW, for fun I measured the LF stations MSF, DCF, and TDF just a few days
> ago. The signals look like this from our site:
> http://www.anderswallin.net/wp-content/uploads/2017/02/MSF.jpg
> http://www.anderswallin.net/wp-content/uploads/2017/02/DCF.jpg
> http://www.anderswallin.net/wp-content/uploads/2017/02/TDF.jpg
>
> I guess the +/- 40 Hz side-bands on TDF are by design?
>
> I have an SDR set up also, so the gnu-radio demodulators could run in
> parallel on each of these, and the sdr sampling clock could come from a
> local clock. One more project on the to-do list...
>
> Anders
>
>
> On Mon, Mar 6, 2017 at 12:42 AM, Iain Young  wrote:
>
> > On 05/03/17 20:23, paul swed wrote:
> >
> > Gilles what signal is that at 162KHz. A European station? Nice thats its
> C
> >> controlled.
> >>
> >
> > That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry
> > the AM Station France Inter as well, but that went when France turned
> > off all LW, MW, and LORAN stations at the end of 2016.
> >
> > The Time Signal is Phase Modulated (I have a gnuradio decoder which
> > works very well if anyone is interested)
> >
> > See https://en.wikipedia.org/wiki/TDF_time_signal and
> > https://en.wikipedia.org/wiki/Allouis_longwave_transmitter
> >
> > With no AM modulation, there are obvious benefits with regards to using
> > it as a frequency reference. Average phase and frequency deviation is
> > zero over 200msec (see link above for details)
> >
> >
> > Iain
> >
> > PS, The signal is used by the French railways SNCF, the electricity
> > distributor ENEDIS, airports, hospitals according to the Allouis link
> > above
> >
> >
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> >
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Re: [time-nuts] Autodesk Eagle -- maybe they're listening

[Graham / KE9H]

Or, switch to the best "free" open source solution, which is KiCad.

Eagle had a bunch of quirks.  I hear KiCad has a different set of quirks.

So a learning curve to get up on KiCad and, for me, an issue migrating ten
years personal library of component foot-prints.

I heard a blogger suggest that if you move to KiCad, make a donation in the
amount of the old $69 Eagle license fee to the KiCad development team.

--- Graham

==



On Mon, Jan 23, 2017 at 10:01 PM, jimlux  wrote:

> On 1/23/17 4:56 PM, Mike Suhar wrote:
>
> Looks like they have a student version but the way I read it you have to
>> actually be a student enrolled in an education institution.  I assume they
>> require some form of proof.
>>
>>
> The usual hack for that is to enroll in a single class at the local
> community college, which you don't need to pass, just enroll, so you get
> the student ID.
>
>
>
>
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Re: [time-nuts] Autodesk Eagle -- maybe they're listening

[Graham / KE9H]

Mike:

You can get Eagle 7.7 at:
ftp://ftp.cadsoft.de/eagle/program/7.7/

Somehow, that ftp server is still up and serving downloads.

--- Graham

==

On Mon, Jan 23, 2017 at 6:56 PM, Mike Suhar  wrote:

> Many companies are trying to jump on the subscription band wagon.  It is a
> way to keep a steady flow of income.  Unfortunately,  hobbyists are left
> out in the cold.   I have version 7.5 with the hobbyist license.  I just
> tried to get 7.7 but the download pulls in version 8.0.  I did not install
> it.
>
> If you are not using the software on a regular basis I assume  you could
> go  with the monthly subscription for a month then drop it.  Pick up again
> a few months later when you start another project and need more than the
> freeware capabilities.
>
> Looks like they have a student version but the way I read it you have to
> actually be a student enrolled in an education institution.  I assume they
> require some form of proof.
>
> Mike
> W8RKO
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of John
> Ackermann N8UR
> Sent: Monday, January 23, 2017 17:14
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Autodesk Eagle -- maybe they're listening
>
> Autodesk just sent a follow-up to my "new price model unacceptable"
> complaint a few days ago.  It looks like they are going to upgrade the
> "Standard" subscription ($100/year) to support 4 layer boards up to 160
> cm2, which I think matches the current standard version capabilities.
> Here's a thread from the Autodesk forum:
>
> http://forums.autodesk.com/t5/eagle-forum/a-path-forward-
> for-the-make-license-a-step-up-for-standard/td-p/6823182
>
> This is effective with the next release, which is supposed to be out in a
> couple of weeks.  (In the meantime, I've made sure to download every flavor
> of installer for version 7.7.0, just in case...)
>
>
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Re: [time-nuts] Autodesk Eagle -- maybe they're listening

[Graham / KE9H]

Hi John:

It is still an effective tripling or quadrupling of the cost.

I purchased a "non profit" license several years ago for $129.  "Non
commercial, 4 layers, up to 160 sq cm., all functionality enabled."
They converted this to a "standard" license over time.
A license was good for the life of a major version, such as 5 or 6.
When 7 came out, I had to buy a new license for 7, but it was at the
existing customer upgrade price, which was $69.

So $129 initially, then $69 every two or three years or so, as new major
versions came out.
Now they want $100 per year.

--- Graham

On Mon, Jan 23, 2017 at 4:14 PM, John Ackermann N8UR  wrote:

> Autodesk just sent a follow-up to my "new price model unacceptable"
> complaint a few days ago.  It looks like they are going to upgrade the
> "Standard" subscription ($100/year) to support 4 layer boards up to 160
> cm2, which I think matches the current standard version capabilities.
> Here's a thread from the Autodesk forum:
>
> http://forums.autodesk.com/t5/eagle-forum/a-path-forward-for
> -the-make-license-a-step-up-for-standard/td-p/6823182
>
> This is effective with the next release, which is supposed to be out in a
> couple of weeks.  (In the meantime, I've made sure to download every flavor
> of installer for version 7.7.0, just in case...)
>
>
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Re: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year

[Graham / KE9H]

Your existing Eagle license should allow you to run your existing version
indefinitely.
I think it would be useful for a few years or so.

I also think your existing license also allows you to run one copy on Mac,
Linux or Windows.
So, if you are on Windows 7 and think you might want to migrate to Linux or
Mac,
go download a copy of the other installers NOW.

They have pulled down the Version 7.7 and all earlier version archive
access on the main
Eagle and AutoCad site, but the cadsoft ftp server is still up and
serving.  I don't expect
AutoCad to allow that to happen for much longer.

ftp://ftp.cadsoft.de/eagle/ 
ftp://ftp.cadsoft.de/eagle/program/7.7/

Running real slow, (overloaded?) so be patient.

The biggest issue with migrating to KiCad for me is walking away from ten
years of
"trusted" parts footprints.  Hopefully an Eagle to KiCad footprint
translator would
become available.

I don't do enough hobby and incidental work to justify the $500 per year
that it would
take to replace my previous $125 every three years or so "Non-profit"
license.

--- Graham

==

On Sat, Jan 21, 2017 at 8:43 AM, paul swed  wrote:

> What can I add to this thats not been said.
> This is how software is moving and it did start with Autodesk who sacked
> there original license model for the subscription approach and is making a
> ton of money that way. Its annuity. A gift that keeps on giving. Meanwhile
> they add bloat-ware for the sake of trying to appear to add some value
> I can go on but as all of you have observed it is what it is. Sitting back
> and griping will not change it. Its a major corporate direction change
> especially if a company was acquired. Its really not going to change. When
> a company is acquired what ever had been stated positions no longer matter.
> Its not the same company any longer, just the same name.
> So exploring alternates as you are all doing is great and helpful.
> Regards
> Paul
> WB8TSL
>
> On Fri, Jan 20, 2017 at 4:42 PM, Bob Camp  wrote:
>
> > Hi
> >
> >
> > > On Jan 20, 2017, at 12:44 PM, Chris Albertson <
> albertson.ch...@gmail.com>
> > wrote:
> > >
> > > It could be what they are doing is purposely trying to "blow off"
> > > their less desirable customers.
> > >
> > > I explained this to someone I know who was upset at a large bank she
> > > deals with.  She said she would move "all her money out of the bank"
> > > all $5,000 of it.I explain to her that was EXACTLY what the bank
> > > wanted and the reason for the policies she experienced.   Small
> > > customers with $5K deposits are not profitable.So Autodesk is
> > > selling subscriptions for $500 and offering "one on one" sport.
> >
> > The last time they played this game they found that reducing the
> > subscriber base 1000:1
> > at $500 a year was not as good as 10:1 at $50 a year.  That’s why I
> > suggest that people
> > wait a bit and see what happens over the next few months. Eagle does not
> > have what it takes
> > to compete as a PCB program for the big guys. There is no great big block
> > of licenses at the Fortune
> > 500 to milk in this case. The user base is large. It is made up of the
> > small, price sensitive guys. Each
> > time the Eagle license stuff has been fiddled in the past, it’s been a
> > disaster because of that.
> >
> > The Eagle “per customer” cost is nearly zero ( unlike a bank ). It’s
> > really all about how much money they
> > bring in each year. Their costs scale more on a per bug …. errr … per
> > feature basis rather
> > than by the customer (at least for the hobby customer). They will charge
> > what they can as long as
> > people keep signing up. If nobody signs up … they will adjust.
> >
> > Bob
> >
> > >
> > > Apple has a neat business model too.   They have like about 18% of the
> > > world's cellphone market but make the MAJORITY of the profit.  What
> > > they do is take the one in five most profitable customers.
> > >
> > > Maybe Autodesk is looking to do the same thing, take only the most
> > > rich customers and let the others go elsewhere.
> > >
> > > In the end nicad might be the best for the hobby market.
> > >
> > > Autodesk is looking to offer the integrated solution where the PCB and
> > > case that it lives in are designed together by a team that is
> > > geographically distributed.
> > >
> > > On Fri, Jan 20, 2017 at 8:58 AM, Bob Camp  wrote:
> > >> Hi
> > >>
> > >> I completely agree that their spin at acquisition and the reality of
> > what just came out
> > >> is completely amazing. They said they would never do this and that.
> > What they are doing
> > >> is exactly what they said they would not do.
> > >>
> > >> It’s a rare board that I do in < 4 layers. It’s also quite normal to
> > have designs above
> > >> 160 CM^2. If I have 4 layers, there *will* be signals on all those
> > layers. That puts me
> > >> squarely in the $500 / yr subscription. A month ago that 

Re: [time-nuts] Lady Heather Version 5 is now available - date formats

[Graham / KE9H]

How did the Mayans deal with leap seconds?

--- Graham

==

On Tue, Dec 13, 2016 at 4:28 AM, Mark Sims  wrote:

> Heather defaults to the unambiguous format 13 DEC 2016.  There is a
> command for showing the date in the ISO format -ddd where ddd is the
> day of the year.
>
> I just added back the -mm-dd format.  It was in there at one time, but
> got lost somewhere along the way...
>
> Why can't the world standardize of the Mayan long count?  Heather can do
> that right now.
> ___
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Re: [time-nuts] Totally unrelated, but..

[Graham / KE9H]

Remember that the internal Voltage reference in the original three terminal
regulator designs is a Zener.
(Zeners are also useful as RF white noise sources.)
The regulator is generally an amplifier with DC feedback.
If you look at the application notes on the early regulators, they require
capacitors to ground on both the input and outputs.
If these capacitors are missing, or too low in value, or not good
capacitors at RF frequencies, then the Zener noise is amplified by the
regulator amplifier and pushed out the output port.
I would experiment by putting a good ceramic 0.1uF cap to ground, right at
the regulator output port.

--- Graham

==


On Wed, Dec 7, 2016 at 10:43 AM, Bob Camp  wrote:

> Hi
>
> You probably have proven one of the most basic design truths: Parts will
> *always* oscillate just
> outside the bandwidth of your test gear” :). A few other possible issues:
>
> 1) Something else is oscillating and it is simply interacting with the
> regulator in an odd way.
> 2) The oscillation / noise is at a very low level and it’s below your test
> gear’s noise floor
> 3) Testing stops the oscillation
>
> Bob
>
> > On Dec 6, 2016, at 4:24 PM, Van Horn, David  backcountryaccess.com> wrote:
> >
> > Lots of discussion on here about low noise regulation so someone may
> know what to look for.
> >
> > I have a receiver which is getting a lot of interference from somewhere.
> > Antenna disconnected, interference still high.
> > After much poking around, we found that replacing a voltage regulator
> with a slightly different part cures the problem.
> > Running that section on external battery is also fine, so it appears the
> original regulator causes some problem.
> > We tried various batteries over a range of voltages within the chip
> spec, and couldn't make it have a problem.
> >
> > I looked at the reg input and output with scope and spectrum analyzer,
> and I don't see anything that indicates excessive noise or oscillation.
> > The PCB layout is as tight as you could ask for. Fat tracks, lots of
> ground, I couldn't lay it out any better.
> > Replacing the input and output caps didn't change anything.
> > Replacing the input and output caps with parts that should be "better",
> like Johanson Tancerams or tantalums has no effect.
> >
> > Just for laughs, we tried a number of different regulator chips, all new
> from the reel.
> > The parts with the quietest and with the most noisy specs caused
> problems.
> > One part, with a noise spec more or less in the middle of the spread is
> the one that works.
> >
> > So what is it that a monolithic regulator (linear) can do which is not
> observable on a scope or SA, which would cause a receiver to think it's
> getting a signal or significant noise in band?
> > Everything else in the system is shut down, I am sure the regulator chip
> is the culprit, but so far I don't see how it's causing the problem.
> > I could just use the quiet chip and move on, but experience tells me
> that I'd just have problems again down the road.  That's voodoo, not
> science.
> >
> >
> > Ideas?
> >
> >
> >
> > --
> > David VanHorn
> > Lead Hardware Engineer
> >
> > Backcountry Access, Inc.
> > 2820 Wilderness Pl, Unit H
> > Boulder, CO  80301 USA
> > phone: 303-417-1345 x110
> > email: david.vanh...@backcountryaccess.com backcountryaccess.com>
> >
> > ___
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> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Graham / KE9H]

If you are going to go battery powered, I would also recommend staying away
from Linux, go with something like a 32 bit PIC32MX or PIC32MZ.  Full
Ethernet stack, RTOS if you need it, can do deep sleep down into the
microamp range when not active.

--- Graham.

On Wed, Nov 30, 2016 at 8:35 PM, Gary Chatters 
wrote:

> There do seem to be a lot of small SBCs out there.  I have used boards from
> Technologic Systems, http://www.embeddedarm.com
> and EMAC, Inc, http://www.emacinc.com
>
> They have numerous models for you to look though.  Some various features:
> - SBC or SoM/CoM on baseboard
> - Various form factors including PC/104
> - Usually with RS-232, USB, GPIO, Ethernet.
> - Many without video.
> - ARM processor
> - Many with industrial temperature range
> - Linux and development environment provided (may not be latest)
> - Lower power then BBB.  One model runs at 0.5 watts.  Many around 1.
>
> Prices generally 2 or 3 x BBB prices.
>
> Gary
>
> On 11/30/2016 03:42 PM, jimlux wrote:
>
>> I'm looking for a small linux single board - similar to RPi or
>> Beaglebone Black, but don't need the HDMI, or video stuff.
>> Preferably without weird connectors, and available for wide temperature
>> ranges (it's for a data logger/collector in the field)
>>
>> What's out there?
>>
>> There's BBB in industrial flavor (-40 to +85C ) for $60-70
>>
>
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Graham / KE9H]

The BeagleBone Green is a BeagleBone Black with the HDMI and video chip
removed.

Mouser Part number *Mouser Part #: *713-102010027, $39, In stock.


Makes a great little headless server.

--- Graham

==

On Wed, Nov 30, 2016 at 3:51 PM, Clint Jay  wrote:

> Raspberry Pi compute module? Maybe even a Pi Zero?
>
> On 30 Nov 2016 21:47, "Adrian Godwin"  wrote:
>
> > The tiny g3 routers are worth looking at. They have WiFi, Ethernet and
> USB,
> > cost very little and will usually run wrt54g Linux. Can be rather short
> on
> > memory though.
> >
> > On 30 Nov 2016 8:43 p.m., "jimlux"  wrote:
> >
> > > I'm looking for a small linux single board - similar to RPi or
> Beaglebone
> > > Black, but don't need the HDMI, or video stuff.
> > > Preferably without weird connectors, and available for wide temperature
> > > ranges (it's for a data logger/collector in the field)
> > >
> > > What's out there?
> > >
> > > There's BBB in industrial flavor (-40 to +85C ) for $60-70
> > > ___
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> > > To unsubscribe, go to https://www.febo.com/cgi-bin/m
> > > ailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
> > ___
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> > To unsubscribe, go to https://www.febo.com/cgi-bin/
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Re: [time-nuts] Inductor core material aging (was: Rohde & Schwarz XSD 2.5 MHz crystal gone bad?)

[Graham / KE9H]

The core of the inductors are commonly powdered iron (of various alloys),
held together with a plastic binder.
The early plastics shrank and changed shape with time, changing the
inductance over decades.
Later binders are much more stable.
Not much you can do about it, other than change the inductors.

--- Graham

==

On Mon, Nov 21, 2016 at 10:14 AM, Bob Camp  wrote:

> Hi
>
> > On Nov 21, 2016, at 9:23 AM, Attila Kinali  wrote:
> >
> > Hoi Bob,
> >
> > On Sun, 20 Nov 2016 22:21:29 -0500
> > Bob Camp  wrote:
> >
> >> 50 year old inductors may have been made with core materials
> >> that aged more than just a little bit. I have empirical data on this :)
> >
> > Do you have that data available somewhere? I would be very much
> > interested in it.
> >
>
> We had a few thousand oscillators that had to be replaced due to coil
> issues
> in the 1970’s. We were not the only ones with the problem. Other outfits
> had very
> similar experiences. Eventually the coil guys took a look at the materials
> and
> “changed something”. After that the coils did not have as much aging when
> run at 100C forever and ever.
>
> Bob
>
> >   Attila Kinali
> >
> > --
> > It is upon moral qualities that a society is ultimately founded. All
> > the prosperity and technological sophistication in the world is of no
> > use without that foundation.
> > -- Miss Matheson, The Diamond Age, Neil Stephenson
> > ___
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Re: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad?

[Graham / KE9H]

Is your oven doing what it is supposed to be doing?

Sounds more like an oven problem than a crystal problem.

--- Graham

==

On Sun, Nov 20, 2016 at 7:00 PM, Alan Melia 
wrote:

> Michael a couple of wild thoughts, make sure there is no 500kHz there
> (this is the crystal fundamental and the maintaining circuit should be
> degenerative there. (Is it a Meecham Bridge?)
>
> That sounds like a baseless IO GT valve (tube in US ) enclosure which was
> probably originally evacuatedhas the vacuum gone soft in 50 years?I
> dont know how you would check, but I think that would cause a lowering of
> the frequency.
>
> Alan
> G3NYK
>
> - Original Message - From: "Michael Ulbrich" 
> To: "Time-Nuts" 
> Sent: Sunday, November 20, 2016 11:49 PM
> Subject: [time-nuts] Rohde & Schwarz XSD 2.5 MHz crystal gone bad?
>
>
>
> Hi there,
>>
>> I'm new to this list and have some interest in quartz crystal and
>> rubidium oscillators - GPS, NTP, PPS and "clock watching" in general ;-)
>>
>> I snatched an R XSD frequency standard accompanied by an XKE frequency
>> controller. Found the manuals on KO4BB's site (Thanks a lot for that!
>> BTW there's a slight mix-up of pages in that some of the XKE pages have
>> found their way into the XSD manual).
>>
>> My initial hope of a quick and easy restoration project faded a bit when
>> I looked at the XSD output frequency after heating up the oven. It was
>> off by about -1 * 10-5 and after cranking the fine tuning for some time
>> and having another look at the specs I realized that the frequency was
>> too far off to be dialed in by the fine tuning which only covers about
>> +/- 2 * 10-7.
>>
>> Next step was to take apart the oven and check series capacitor,
>> oscillator and the crystal itself. I found that even the coarse
>> adjustment range of the cylindrical series capacitor (40 - 110 pF) would
>> not allow to pull the crystal to it's specified frequency. When
>> replacing the series cap by a ceramic and lowering the value to just
>> before the oscillation breaks down (about 10 pF) I managed to set the
>> oscillator frequency offset to  +2.5 * 10-6 at room temperature. But
>> even this will not suffice when taking into account that the frequency
>> will drop by a few parts in 10-5 (cf. XSD manual) when the oven heats up
>> to its operating temperature. I also checked some of the components on
>> the oscillator PCB which might have an influence on frequency but could
>> not find any fault.
>>
>> The crystal itself is a disk of about 30 mm diameter mounted in a sealed
>> glass cylinder of about 38 mm dia. and 43 mm height. There is no socket
>> just 2 bare wires.. It does not show any visual signs of damage.
>> According to a reference given in the R XSD manual the crystal's
>> construction follows a publication from A.W. Warner "Design and
>> Performance of Ultraprecise 2.5-mc Quartz Crystal Units" in Vol 39,
>> Issue 5 of Bell Labs Technical Journal (Sept. 1960). According to that
>> it is an AT-cut 5th overtone design.
>>
>> Now my questions:
>>
>> a) Considering that this gear is about 50 years old, a "crystal gone
>> bad" situation shouldn't be that much of a surprise, right?  But could
>> there be any other cause of the "huge" frequency offset besides a bad
>> crystal? I would very much appreciate any idea that I could try to get
>> this baby back on spec.
>>
>> b) if nothing else helps: Could any of you give me a hint about who
>> might be able to supply a spare crystal? I tried my directly reachable
>> contacts but unfortunately to no avail so far. Please consider that
>> similar crystals might also have found their way into other
>> manufacturer's constructions from that era - Sulzer, Racal, HP ... you
>> name it ...
>>
>> Many thanks in advance!
>>
>> Best regards ... Michael U.
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>
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Re: [time-nuts] How can I measure GPS Antenna quality?

[Graham / KE9H]

You need a definition of "Quality" to work with.

One definition might be "does it meet published specs? under what
conditions?"
Another definition might be associated with reliability and ruggedness.
Longevity in outdoor conditions.
Another might be with the antenna supporting your use case.
Another might be with suppression of reflections and spurious signals from
below the horizon.

So, the definition of "Quality" might change drastically with the use case
and from your expectations as to its cost.

If you have a definition of your quality criteria, then this crowd can
probably tell you what to measure and how to analyze the measurement data.

--- Graham

==

On Sun, Nov 20, 2016 at 4:13 PM, Hal Murray  wrote:

>
> Is that even a sensible question?  Is there a better way to phrase it?
>
>
> The problem I'm trying to avoid is that the weather and the satellite
> geometry change over time so I can't just collect data for X hours, switch
> to
> the other antenna or move the antenna to another location, collect more
> data,
> then compare the two chunks of data.
>
> The best I can think of would be to setup a reference system so I can
> collect
> data from  2 antennas and 2 receivers at the same time.  It would probably
> require some preliminary work to calibrate the receivers.  I think I can do
> that by swapping the antenna cables.
>
>
> If I gave you a pile of data, how would you compute a quality number?  Can
> I
> just sum up the S/N slots for each visible/working satellite?
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] I love the smell of tantalum in the morning

[Graham / KE9H]

If you are in a position where you are worried about damaging the PCB.
(And I would really be worried cutting any part in half with cutters, or
cutting leads off an IC with diagonal cutters.)
For two leaded parts, "Hot tweezers" work fine.
For parts with more leads, like ICs, you need hot air tools.

If you don't have those tools, or you have an unusually expensive or rare
PCB, consider low temperature solder.

You can buy a kit (from Mouser or others) for $16 called "ChipQuik" SMD1

Watch the video:
http://www.chipquik.com/store/product_info.php?products_id=210001

Manufacturer's Part number SMD1
Mouser part number: 910-SMD1

Remove as much normal (lead containing or lead-free) solder as you can from
each lead with solder wick.
Flood each pin with the low temp solder alloy (melting temp about 136
degrees F or 58 degrees C)
Usually putting a soldering iron on any one pin (or use a hot air pencil)
will raise the entire part and nearby board above 136 degrees F, so just
pick the part off with tweezers.
Now clean off all the low temp solder with solder-wick or as instructed.

For $16, you get enough for several years of casual reworks.
This is much gentler on the PC board than any other technique.

--- Graham

==

On Sun, Nov 6, 2016 at 2:42 PM, Bryan _  wrote:

> If the SMD is small enough I have found it easy to remove by just applying
> a blob of solder to one end, this will quickly gap over to the other lead,
> and the SMD component and solder ball just slides off the board. Only works
> on the very small components though.
>
>
> -=Bryan=-
>
>
> 
> From: time-nuts  on behalf of Robert
> LaJeunesse 
> Sent: November 6, 2016 8:42 AM
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
> Another admittedly low-budget way of heating both ends is to use a heat
> spreader. Solder a short piece of braid to one component end, fold it over
> the top of the part, and solder it to the other end. Heat the braid in the
> center, add solder until both ends are melted, and lift the combination off
> with tweezers. Sometimes a heavy enough copper wire bent around the part
> will also work as the heat spreader..
>
> Bob LaJeunesse
>
> > Sent: Saturday, November 05, 2016 at 9:05 PM
> > From: "Andy ZL3AG via time-nuts" 
> > To: "Discussion of precise time and frequency measurement" <
> time-nuts@febo.com>
> > Subject: Re: [time-nuts] I love the smell of tantalum in the morning
> >
> >
> > Yes. Unless you're grinding it away with a dremel (which I wouldn't
> recommend as far as chemical dust is concerned), nibbling away with
> sidecutters would be trying to force the 2 ends of the component apart.
> That may be stressing the pads they're soldered to, leading to a possible
> pad lifting at some stage.
> >
> > Any of the methods mentioned that heat both ends at the same time -
> allowing the component to be wiped off the board - would have to be the
> best, stress-wise.
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Re: [time-nuts] Opening an Isotemp OCXO

[Graham / KE9H]

Here is the TI document on "Case Marking."  It may not be a 74S30.

http://www.ti.com/lit/an/snoa039c/snoa039c.pdf

--- Graham

==

On Fri, Oct 28, 2016 at 11:27 AM, Adrian Godwin  wrote:

> That's one sweet soldering iron. Is it an American Beauty ?
>
>
> On Fri, Oct 28, 2016 at 4:31 PM, Peter Reilley 
> wrote:
>
> > I did finally get it open.   I used a very large old style soldering
> > iron and .003 inch steel shim stock.   I would melt the solder on the
> > straight seams and insert small pieces of the shim.   Solder does not
> > stick well to steel so the shim kept the soldered seam open.
> > I used a soldering iron rather than a torch because I can control the
> > temperature.
> >
> > I could not use the shim at the corners.   After all the straight seams
> > were separated I could pull each corner using a screw in the mounting
> > hole and melt the solder at the corner.   Slowly working my way around,
> > corner by corner, I got it opened.   I did not damage anything so I
> > should be able to close it up after I fix it.
> >
> > Looking around with my scope it seems that the output driver chip is bad
> > as I expected.   It is a TI 14 pin surface mount DIP.   It says S30 on it
> > which if it is a 74S30 it is an 8 input positive NAND gate.   The board
> > layout confirms this as the 10 MHz signal is connected to pin 2 and all
> > other inputs are tied high.   Pin 8 is connected to the output.
> >
> > The chip is run off 12 volts so it must be CMOS.   But I cannot find any
> > chip like that that will run off 12 volts.   Any suggestions for a
> > replacement?
> >
> > Also, using an 8 input NAND chip for a driver seems an odd choice.
> >
> > When I put 12 volts on the unit the S30 chip gets really hot. After I
> > removed the chip the unit seems to work OK.   The current jumps between
> > about .1 amp to .9 amps.   It seems like the temperature regulator is
> > an on/off type controller.
> >
> > The device on eBay, item 261920574725, looks exactly like what I have.
> >
> > I have placed a bunch of pictures in my dropbox.
> > https://www.dropbox.com/sh/52e9d1rva9kpb3w/
> AABmbIj1aK7Zk2J9SNMmu-JAa?dl=0
> >
> > Pete.
> >
> >
> >
> >
> > On 10/18/2016 10:57 AM, J. L. Trantham wrote:
> >
> >> Pete,
> >>
> >> I'm not familiar with your OCXO but I found one shown on 'theBay' (item
> >> 261920574725) and it appeared to have an option for 'mounting screws',
> four
> >> of them, on the bottom.  Interestingly, the 'link' to the datasheet for
> >> that unit did not show threads for mounting screws.
> >>
> >> If your unit has that option, I would suggest placing four long screws,
> >> mounting the item in a vise, use a small torch (I've used a hand held
> >> propane torch turned down very low to open a number of units from
> 5061A's)
> >> around the bottom of the case while gripping the top with an appropriate
> >> sized Channel Lock plier and lifting off the top.
> >>
> >> If you can repair the OCXO, it should be easy to reassemble the unit
> with
> >> solder.
> >>
> >> TheBay unit looks like it has a screw cover (which likely has a rubber
> >> gasket) for mechanical adjustment of the frequency.  I'd remove that
> before
> >> applying the torch. :^).
> >>
> >> If you get it open, I'd love to see some pictures of the insides.
> >>
> >> Good luck and hope this helps.
> >>
> >> Joe
> >>
> >>
> >>
> >> -Original Message-
> >> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter
> >> Reilley
> >> Sent: Tuesday, October 18, 2016 8:11 AM
> >> To: time-nuts@febo.com
> >> Subject: [time-nuts] Opening an Isotemp OCXO
> >>
> >> I bought an Isotemp OCXO82-59 with a frequency of 10 MHz for a $3 at the
> >> MIT flea market.
> >> As expected it was dead.   It heats up as expected but looking at the
> >> output with a scope there
> >> is nothing.   However looking at the output with a spectrum analyzer I
> >> can see a faint 10 MHz
> >> signal.   It seems that the oscillator is running but the output
> >> circuitry is dead.   Reasonable
> >> assumption?
> >>
> >> Anyway, has anyone had any luck unsoldering the tin case without
> >> destroying it?
> >>
> >> Pete.
> >>
> >> ___
> >> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >>
> >>
> >>
> > ___
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> > To unsubscribe, go to https://www.febo.com/cgi-bin/m
> > ailman/listinfo/time-nuts
> > and follow the instructions there.
> >
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Re: [time-nuts] For those that insist on using switching power supplies

[Graham / KE9H]

Actually, if they have the "CE" stamp on the product, then they have very
specific radio interference limits that they must test and meet.
It must have been tested, certified, and the certification package
available for inspection.

Whether they actually met it, then pulled the interference supression parts
off the board as a "cost reduction" as is common in no-name computer power
supplies, or whether it never met it to begin with, is for you to
speculate.  Some suppliers will explain to you that "CE" means China
Export, not that it meets the consolidated European safety and electrical
rules.

--- Graham



On Thu, Oct 13, 2016 at 5:25 PM, Nick Sayer via time-nuts <
time-nuts@febo.com> wrote:

>
> > On Oct 13, 2016, at 6:05 AM, Van Horn, David  backcountryaccess.com> wrote:
> >
> > To be fair here, phone chargers have almost no requirement to be quiet
> other than conducted and radiated emissions limits.
> > It’s charging a battery.
>
> Not quite. They power the device in question *while* they’re charging the
> battery. Now, I’ll admit that powering a phone is a much lower bar than
> powering, say, an audio amplifier, but I’d also say that some of the
> devices on that page were pumping out way more garbage than even any
> digital system should have to put up with.
>
>
> >
> > As a designer of some fairly quiet SMPS systems, this feels like “look
> how bad a family car this tractor is".
>
> Well, there’s some of that, but the worst offenders were counterfeit
> devices that were pumping out unreasonable levels. To your analogy, they
> were the outer shell of a family car with a the engine from an Edsel
> installed in it without a muffler or any emissions controls fed from an
> open bucket of gasoline sitting on the passenger’s seat.
>
> ___
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Re: [time-nuts] New PPB rated TCXO

[Graham / KE9H]

If you have a legitimate application for the part, and some volume
associated with the application, and you convince their sales person of
that, then the data sheets are made available.
--- Graham

On Tue, Oct 11, 2016 at 8:01 AM, jimlux  wrote:

> On 10/10/16 11:27 PM, djl wrote:
>
>> But how the heck did they get some? According to the website, even data
>> sheets are not available.
>> Don
>>
>
> It's not unusual for one to be able to get small quantities of a
> pre-release product if you have a relationship with the manufacturer/sales
> engineers. Typically it's bound up with an NDA, and the datasheet is NDA,
> and you basically have an agreement that if it turns out poorly so they can
> redesign/retool/fix it, you tell the mfr about it, and don't go
> broadcasting to the world that this new part is junk.
>
> In otherwords, not everything is available through distribution and
> mail-order.
>
> This is one of the arguments I make as to why attending in-person
> conferences is a good thing - that's how you make those personal
> connections.
>
>
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Re: [time-nuts] Need Time Help

[Graham / KE9H]

For the group. This ham is trying to work EME. Earth-Moon-Earth propagation
path. Aka, "moonbounce."

He is trying to time synchronize a system, where the other station he is
communicating
with can be any other place on the Earth that can also see the Moon.

So the system time sync is for a little bit tougher case than a local area
network.

--- Graham

==

On Wed, Oct 5, 2016 at 6:14 AM, Bob Camp  wrote:

> Hi
>
> If you buy a GPS receiver and get it set up for timing …. just use it.
> Then there is no
> need for NTP at all….
>
> Bob
>
> > On Oct 5, 2016, at 12:33 AM, Chris Albertson 
> wrote:
> >
> > On Tue, Oct 4, 2016 at 6:52 PM, Bob Camp  wrote:
> >
> >> Hi
> >>
> >> If:
> >>
> >> 1) You are a typical Ham in a home environment
> >> 2) All the servers are “out there” on the internet
> >> 3) You have any of the normal modems feeding your home
> >>
> >> You have a very basic issue in terms of path delay. All the servers you
> >> can access
> >> have the *same* asymmetric delay. In that case, no matter how many
> servers
> >> you
> >> add to the ensemble, the situation never gets better. You are always
> stuck
> >> with the
> >> (likely unknown) uplink / downlink delay difference of your modem.
> Exactly
> >> what
> >> that number is depends a *lot* on the modern and the system feeding the
> >> modem.
> >> It is *very* possible to see static delay asymmetry well beyond the 5 ms
> >> that the OP is after.
> >> On most systems there is also a dynamic asymmetry that is related to
> >> loading. That
> >> just makes things harder to work out …..
> >>
> >
> > But this is easy to measure, you buy a GPS receiver and use that as an
> 8th
> > or 6th reference clock along with the 5 or 7 Internet servers then you
> look
> > at the difference between GPS and the Internet servers.  The Internet
> > servers do much better than you'd think.  Not as good as GPS but really
> > good.  Why?
> >
> > Because NTP normally never actually sets you clock to match a server's
> > clock.   It adjusts the RATE of your clock so the it cruises on the
> middle
> > of the pack of vetted servers.  It adjusts your clock over a long period
> to
> > it has the benefit of averaging out lots of random behavior.   The result
> > is that you can keep within a few milliseconds of the GPS even with tens
> of
> > millisecond of delay in the communication path.
> >
> > For people new to NTP, the algorithm has it's hands the system clocks
> > "fast/Slow? lever and never normally moves the clocks hands directly
> >
> > And all those Internet servers do NOT have the same asymmetric delay.
> Well
> > they might but that would be a pathological case.  Typically delays
> really
> > are more symmetric than not (one way trip really is 1/2 the round trip)
> > The clocks that don't meet this assumption are found and removed from the
> > pool.   It works because the dells are NOT the same but random  Ans like
> I
> > said, it is easy enough to measure.  You can see that peer offsets are
> all
> > over the map
> >
> > Also your modem is likely not causing an asymmetric delay.  That modern
> > wetter is is the old phone kind or a fiber optic system only takes you to
> > the fist router.  The modern likely has the same time of flight in both
> > directions.   The delay is cause by a queue some place of packets that
> are
> > aggregated from many users.  These are random  but sort of predictable.
> A
> > packet going across a continent or will see more of this then going to a
> > nearby server
> >
> >
> >> Bob
> >>
> >>> On Oct 4, 2016, at 9:05 PM, Chris Albertson  >
> >> wrote:
> >>>
> >>> The problem, I think with your Internet sync's NTP servers is you are
> >> only
> >>> using one server S.  The most common practice is to use 3 to 5 with 5
> >> being
> >>> about the right number.   If you get Ntp enough Internet servers to
> work
> >>> with it can detect problem like asymmetric path lengths which I'm sure
> is
> >>> you problem.
> >>>
> >>> NTP solved the problem that stumped a few people back in the 1970's of
> >> how
> >>> to sync two clocks when there is a long delay and not constant in there
> >>> communications path.  (Of course the problem is simple if the delay is
> >>> known and well measured)  But the solution required the the average
> path
> >>> delay is the same going in each direction.  worse no software can't
> know
> >>> there is an asymmetric delay.  Well not unless it is using a few
> servers.
> >>> NTP basically finds then ignores the "problem servers".
> >>>
> >>> PTP solves the problem by requiring that all the network hardware has
> >>> special time stamp ability that is designed to work with PTP.  This
> >>> hardware is rare unless the user provides it.  So PTP can't really work
> >> on
> >>> the public Internet.
> >>>
> >>> You CAN do very well, to just a few Millisecond using NTP sync'ing to
> >>> Internet servers, but pick 5 of them or even 7.  and 

Re: [time-nuts] Need Time Help

[Graham / KE9H]

Larry:

You have multiple problems, with the way you are trying to define
"time-error."

I think you are defining it as the time error of the signal coming out of
your receivers/decoders.

You are blending all the error/delay sources together, and you need to
break them apart, since each one will have a different solution, or method
of management

First, the reflector has already jumped in and helped you with the
definition of absolute time.  You can get single digit millisecond accuracy
(with some caviats and bewares) from NTP, for stations at different
locations.  You should be able to get single digit microsecond accuracy (or
better) with an appropriate GPS based timing systems. You can not get these
levels of accuracy out of the native time system on Windows. That is more
like single digit seconds.

Second, you have some serious signal processing latency delays in your
receivers/demodulators/decoders.  Depending on how the designer has dealt
with streaming and buffering, particularly with the (buffered) connections
between the stages, these processing latency delays may be constant or
variable, or perhaps adjustable.  The Windows Sound system is horrible from
a latency/stability standpoint. You are probably feeding your back-end
demodulators/decoders through it. You will need to break apart your system
(transmit and receive) into modules or stages, and characterize each one
for latency. Beware of (uncontrolled) buffers at the interfaces. You
generally need to pick a reference point, such as the antenna port, and
correct everything to that reference point.

Third, you seem to be running a portion of the (SDR) receivers and the
demodulators/decoders on computers with Operating Systems. (Like WIndows
OS, which is NOT a real-time operating system.)  That means that the
response time of the system to a request for computing resources can be
quite variable. (microseconds to tens of milliseconds typical, with rare
excursions into the single digit seconds.)  The solution to this problem is
to either run on a very lightly loaded computer, or switch to a real time
OS, such as Linux with a real-time kernel. This does not cure the problem,
but does put bounds on it.

--- Graham / KE9H

==

On Tue, Oct 4, 2016 at 7:03 AM, Bob Camp <kb...@n1k.org> wrote:

> Hi
>
> As others have mentioned, you have two strikes against you:
>
> 1) Modern laptops *love* power saving. That makes them poor time keepers
> at the millisecond level. It takes some well thought out software in the
> OS to
> keep track of all the strange things they do.
>
> 2) Windows XP is getting a bit old and tired. It’s internals were done
> long ago
> on hardware very different than what we have today. It has a lot of
> limitations.
>
> Between the two, you will always struggle. An RTOS would do much better
> than
> XP for timing. Virtually all of the more modern OS’s (some of them free)
> will
> handle timing better than XP does. That’s not to say the laptop will not
> ultimately
> limit what you can do.
>
> There are a few more strikes when you try do do NTP over a residential
> internet
> connection. Cable modems and the like are not designed for high accuracy
> timing.
>
> By far the best solution is to get timing from a GPS. Even a cheap on,
> running over
> a lousy cable will get you into the 1 us region if it’s a modern unit.
> That is way
> better than the 5 ms that you are after. Moving it around on a local LAN
> with
> good cabling isn’t going to degrade it by much over 1 ms, even using NTP.
>
> One alternative to the whole “computers are a mess” issue is to simply put
> the
> GPS into the same hardware that is receiving / transmitting the signals .
> There
> are a *lot* of GPS modules on the market that will put out an accurate PPS
> signal.
> Depending on how picky you are, they are in the $10 to $50 range. Let the
> local
> hardware do the job rather than network the whole thing. Local hardware
> running
> a reasonable OS is in the $30 to $100 range, again depending on features.
> Given
> that you probably already have the price of a small car tied up in antenna
> systems,
> this isn’t that crazy a cost.
>
> Bob
>
>
> > On Oct 4, 2016, at 12:41 AM, Larry Hower <ho...@hower.net> wrote:
> >
> > Hello to the List:
> >
> > After a long and bitter struggle with XP and WIN 10, I am writing to ask
> > for some help in solving some problems we have been having in our attempt
> > to establish a very accurate time reference for use in EME activities.
> >
> > We are hoping to achieve less than 5ms deviation, although anything below
> > 15ms will be adequate for now.
> >
> > Specifically, we want to use a universal reference that will enable
> amateur
> > radio operators in different

Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Graham / KE9H]

A good source for experimenters / home builders of small quantities of
tin-lead solder paste is:

http://kd5ssj.com/
http://kd5ssj.com/solderpaste

The supplier, Cash Olson, KD5SSJ, is an amateur radio operator that for
some extra pocket money in his retirement, repackages fresh Kester 256
solder paste into syringes of about 0.5 CC per syringe, and sells them mail
order for $5, postage included (in US).

One of his syringes is enough to assemble several boards.  They last about
a year if stored in a refrigerator.

--- Graham

==

On Thu, Aug 18, 2016 at 9:40 PM, Bob Albert via time-nuts <
time-nuts@febo.com> wrote:

> I have a Chinese hot air gun with several nozzles.  Mine are the
> quarter-turn type but that doesn't work too well due to sloppy tolerances.
> I have had nozzles fall off in the midst of use.  With some care they can
> be made to stay on, and if necessary bend them a bit to make them more
> secure.
> I have used my hot air device a lot but only for disassembly.  For
> assembly, as I mentioned earlier, I would want to use solder paste.  I
> can't control the hot air well enough to heat just a bit of solder from a
> spool, and clipping off a piece while trying to put it where it belongs is
> a poor system.  So the paste seems to be the way to go.
> Someone needs to invent a low cost paste that doesn't spoil in a few
> months.  It does seem that the Mechanics paste might be an answer to this;
> I would keep it refrigerated although that might be locking the barn door
> after the theft.
> Again, I am not trying to meet some government soldering specification; I
> just want something to work without a lot of fuss and cost.
> What do major companies do when they discover their stuff is outdated?  I
> need a connection to some of those people, maybe pick up some of it now and
> then at low cost.
>
> Bob
>
>
> On Thursday, August 18, 2016 7:26 PM, Bob Stewart 
> wrote:
>
>
>  The stuff I use is Chipquik SMD291AX.  The first syringe of it I bought
> was from Mouser and was 15 grams.  That was back in 2014.  The second
> syringe I got was SMD291AX10, which is 35 grams.  It's dated 3/15/16, so
> you can see how long solder paste will last if you take reasonable car of
> it.  I pumped about 15 grams of that into the original syringe and put them
> both in the fridge.  I've had the small one out on the workbench for
> several weeks now, and there doesn't seem to be a problem.  I fold a piece
> of tape around the needle when it's not in use to keep the air out.  When I
> pull the tape off, I pump out about a 1/4" string and throw that away.  The
> rest works just fine.
> If you haven't switched to using a hot air gun, I strongly suggest it.
> They take a bit of getting used to, but after that, they're a time-saver.
> I have the cheap ebay solder station labeled 852D+.  It has solder pencil
> and hot air.  There are two things I don't like about it.  One is that you
> can't turn the air flow down enough to use narrow nozzles for anything
> other than blowing soldered components off the board.  But it's Much better
> than trying to use a pencil for that chore!  The other is that the tips are
> attached by tightening a screw.  There are units out there that have a
> little tool that you use to give the tip a 1/4 turn twist to attach.  I
> don't change tips much, but not having to wait for the hot air gun to cool
> down would be nice.  The first time you reach for the hot air gun to shrink
> tubing or to solder the center pin for an SMA connector, you know you've
> "arrived".
>
> Bob
>  -
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
>
>   From: Bob Albert via time-nuts 
>  To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
>  Sent: Thursday, August 18, 2016 8:49 PM
>  Subject: Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)
>
> I don't care about lead-free since I am not manufacturing, just repairing
> or building or experimenting.  But there seems to be more than one way to
> view this stuff.  Yes, it might be expired, but some say that's not a major
> issue.  I can't justify the prices asked by US distributors, especially in
> light of the fact that I use very little.  So the fresh stuff, carefully
> refrigerated, would be expired by the time I use the second or third scoop
> of it, anyway.
> What's a casual experimenter to do?
> Bob
>
>
> On Thursday, August 18, 2016 3:33 PM, Chuck Harris 
> wrote:
>
>
>  The Chinese are certainly using a lot of solder paste, so they
> are a source.  I tend to buy mine from Mouser, Digikey, TekSource,
> places like that.
>
> The last stuff I bought was made by Kester, and came from TekSource.
>
> The only problem with using the real sources is in the summer, they
> will pack your paste in an ice pack, and send it over night unless
> you insist otherwise (and 

Re: [time-nuts] Working with SMT parts.

[Graham / KE9H]

The best type of stereo microscope to use for SMT assembly is referred to
as an "Inspection Microscope."
Magnification greater than 10 is not needed or desirable for normal
assembly.
Something in the range of 5 to 10 works well.
A wide field of view and a good light source are desirable.

Just as Brooke says, my "zoom" always stays on the lowest setting. (Same as
his, 0.7 times 10x = 7)

--- Graham

==

On Thu, Aug 11, 2016 at 1:57 PM, Brooke Clarke  wrote:

> Hi Bob:
>
> I don't think it's so much the stereo microscope as the related
> equipment.  I have a Bausch & Lomb StereoZoom 4  and the dial is always at
> the lowest setting (0.7dial * 10X objective = 7 power).
> For another reason I got a Nikon SMZ-U microscope and discovered that it's
> so tall that it can not be used for SMT work.
> http://www.prc68.com/I/NikonSMZ-U.html
> So an important parameter is is length from the eyepiece to the
> objective.  If that get to be long then you can not easily use it.
>
> Using an arm type support is very desirable.  These have a heavy metal
> base with an horizontal arm.  You can swing the arm over whatever you're
> working one and easily move the scope up or down as needed.
> This all done while in a standard chair on a work bench/table.
>
> Although an old fashioned illuminator will work, see top photo:
> http://www.prc68.com/I/SMT.shtml#Mag
> A ring light is much more convenient (scroll down a little).
>
> Also the soldering iron tip to grip distance should be as short as you can
> get.  (1.5" = burned fingers, 0.5" should be better)
>
> --
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> The lesser of evils is still evil.
>
>  Original Message 
>
>> What are the important parameters regarding purchase of a stereo
>> microscope?  I see some on ebay for around $50; are those good?
>> Bob
>>
>>  On Thursday, August 11, 2016 10:00 AM, Didier Juges <
>> shali...@gmail.com> wrote:
>>
>>   I concur. I have been using ExpressPCB extensively over the last 2 years
>> with great satisfaction now that it is possible to get Gerber files from
>> them.
>> I typically use the mini board pro service (3 bare boards, 2 sided with
>> solder mask and silk screen) for prototypes and then buy the Gerbers to
>> have production quantities done overseas.
>> The boards are of high quality and the service is very fast at a very
>> reasonable price.
>> The only gotcha with regard to Gerber files is that you can only buy
>> Gerbers for boards that you have actually bought from them, so the process
>> is to buy the prototypes, then if you are happy with those, buy the
>> Gerbers
>> for that design.
>>
>> Didier KO4BB
>>
>> On Tue, Aug 9, 2016 at 3:06 PM, Brooke Clarke  wrote:
>>
>> Hi:
>>>
>>> I've had good luck using any of the the ExpressPCB services that include
>>> solder mask with surface mount parts where the pitch is 0.05" (half
>>> normal
>>> DIP) and hand soldering (requires stereo microscope).
>>> http://www.prc68.com/I/BTSG.shtml (battery top signal generator)
>>> http://www.prc68.com/I/Images/ICS525v1o.jpg
>>>
>>> http://www.prc68.com/I/SMT.shtml 
>>>
>>> --
>>> Have Fun,
>>>
>>> Brooke Clarke
>>> http://www.PRC68.com
>>> http://www.end2partygovernment.com/2012Issues.html
>>> The lesser of evils is still evil.
>>>
>>>
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>>>
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>> and follow the instructions there.
>>
>>
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>>
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Re: [time-nuts] phase noise in digital divider, 2nd harmonic

[Graham / KE9H]

It is not traditional phase noise, and not a normal Nyquist filtering
problem, but, yes, presence of significant second harmonic energy in your
DDS output will shift/dither your squaring input.

It is hard, with practical filters and filter components to get much better
coverage than one-half octave per low-pass filter.  It will be set by how
much second harmonic content you can tolerate. That is, how far down the
low-pass filter slope the second harmonic needs to be to get the
performance you want.

So using the one-half octave per filter "rule of thumb" then you might need
three or more low pass filters, depending on the actual frequency span
output you are dealing with.

--- Graham

On Thu, Jul 28, 2016 at 6:39 PM, life speed via time-nuts <
time-nuts@febo.com> wrote:

> Hi,
>
> Been a while since I visited, I recall there are many, well, time nuts
> here.  I am trying to track down a source of phase noise in a frequency
> synthesizer design.  One part of the frequency reference upconverts a DDS
> and then divides it down again using a digital divider - standard technique
> for DDS angle modulation spurious reduction.
>
> The DDS tunes over more than an octave, so obviously the single low pass
> filter isn't going to cut it.  I am noticing up to 3 dB phase noise
> degradation at the output of the divider as the DDS frequency decreases and
> the 2nd harmonic is in-band to the LPF.  I suspect this is disturbing the
> threshold crossing in the high speed digital logic divider, as described in
> "The Effect of Harmonic Distortion on Phase errors in Frequency
> Distribution and Synthesis" by F.L. Walls et al at NIST.
>
> What do you think?  I should probably put in a switched filter to get my 3
> dB back  ;)
>
> - Lifespeed
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Re: [time-nuts] Q/noise of Earth as an oscillator

[Graham / KE9H]

42

On Sat, Jul 23, 2016 at 7:59 PM, Hal Murray  wrote:

>
> t...@leapsecond.com said:
> > Earth is a very noisy, wandering, drifting,
> incredibly-expensive-to-measure,
> > low-precision (though high-Q) clock.
>
> What is the Q of the Earth?  It might be on one of your web pages, but I
> don't remember seeing it.  Google found a few mentions, but I didn't find a
> number.
>
> I did find an interesting list of damping mechanisms in a geology book.
> Geology-nuts are as nutty as time-nuts.  Many were discussing damping of
> seismic waves rather than rotation.
>
> I've seen mention that the rotation rate of the Earth changed by a few
> microseconds per day as a result of the 2011 earthquake in Japan.  Does
> that
> show up in any data?  Your recent graph doesn't go back that far and it's
> got
> a full scale of 2000 microseconds so a few is going to be hard to see.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] OT stuffing boards: was GPS interface/prototyping board

[Graham / KE9H]

Don Latham said
to Discussion
I do not see why a small pick and place assist system could not be built on
a 3-d printer.


Lots of problems to be solved...

How do you take loose parts or cut tape or tape reels and get the right
part out, and into the chuck, oriented in the right direction?
How many different kinds of parts, sizes, shapes, pin counts, IC
footprints, can you handle at once?
How do you know it is the correct part?
How do you know where the "+" end, or "pin 1" is?
How do you know that there actually is a part in the chuck?
How do you know the part in the chuck is oriented the way you expected it?
How do you know where the footprint on the circuit board is located? (to a
few thousandths.)
How do you know the part left the chuck and ended up where you intended it
to be?

Commercial systems have answers to all of these questions. In many cases
involving intelligent vision systems.

Once they are all answered, then you have a PCB unique set-up / programming
effort to instruct the placement machine all about today's specific board
and parts list to be assembled.

I can usually build one or two boards by hand about as fast as an engineer
can do the placement machine specific PCB programming and verification.

--- Graham

==






On Fri, Jun 24, 2016 at 11:52 AM, Don Latham  wrote:

> I do not see why a small pick and place assist system could not be built
> on a 3-d printer.
> Don
>
> > On Jun 24, 2016, at 8:32 AM, Attila Kinali  wrote:
> >
> > On Thu, 23 Jun 2016 20:16:34 -0500
> > Oz-in-DFW  wrote:
> >
> >> 1. Pick and place machines use a lot of floor space (even for the
> >>"small" ones are more than 1/2 a bench.)
> >> 2. Even the best ones require pretty continuous tuning. If you aren't
> >>using them continuously each new run is a new and different
> >>experience.  Often unpleasant for the first few scrapped boards.
> >
> > The trick is to use semi-manual pick machines for low volumes.
> > Ie machines that you do not program, but guide by hand. This allows
> > faster and more accurate placing of components than would be possible
> > with a pure manual process, but does not have any of the complexity
> > of the fully automated solutions. The components do not need to be
> > 100% exactly centered, as the surface tension of the molten solder will
> > pull the parts into place (which is also the reason why the copper inside
> > the solder resist mask should be symmetric).
> >
> > These machines are still all pretty expensive (IMHO, the cheapest
> > start from around 2kusd IIRC), but with the continuous growth of the
> hobbyist
> > market, and that market becomming more and more professional/proficient,
> > the production volumes of these  machines will for sure rise and thus
> become
> > cheaper. I am pretty sure that we will see hobbyist marketed pick
> systems
> > build upon open source based control systems in the next couple of years.
> > There are already a couple of DIY systems out there, that look quite
> good.
> > e.g
> http://vpapanik.blogspot.de/2012/11/low-budget-manual-pick-place.html
> > http://www.briandorey.com/post/Diy-Manual-Pick-and-Place-Machine-part-1
> >
> >
> >> Solder stencils make **all** the difference.
> >
> > Oh, yes! Please, do not try syringe dispensers! These fail more often
> than
> > they work. Also pay the additional couple of bucks to get a steel stencil
> > instead of a kapton one. Especially if you make more than one or two
> boards
> > or those with fine pitch.
> >
> >   Attila Kinali
> >
> > --
> > It is upon moral qualities that a society is ultimately founded. All
> > the prosperity and technological sophistication in the world is of no
> > use without that foundation.
> > -- Miss Matheson, The Diamond Age, Neil Stephenson
> > ___
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> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
>
> Felix qui potuit rerum cognoscere causas.
> Lucky is he who has been able to understand the causes of things.
> Virgil
> ---
> "Noli sinere nothos te opprimere"
>
> Dr. Don Latham, AJ7LL
> Six Mile Systems LLC, 17850 Six Mile Road
> Huson, MT, 59846
> mailing address:  POBox 404
> Frenchtown MT 59834-0404
>
> VOX 406-626-4304
> CEL 406-241-5093
> Skype: buffler2
> www.lightningforensics.com 
> www.sixmilesystems.com 
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Re: [time-nuts] OT stuffing boards: was GPS interface/prototyping board

[Graham / KE9H]

We use
"Advanced Assembly" in Colorado for prototype assembly.
http://aa-pcbassembly.com/

For just one or two boards, it is faster to hand solder the parts, as long
as no BGA's or similar.

If complex soldering like BGAs, or more than three boards, we use a proto
assembly house.

--- Graham

==

On Thu, Jun 23, 2016 at 7:58 PM, Chris Albertson 
wrote:

> This is a very important topic for anyone who wants to build state of
> the art electronic today.   You can't continue to live in the 1970s
> using DIP parts with 0.1 inch leads.  So how to make small batches of
> custom designs.
>
> The pick and place machine could be very inexpensive if you are
> willing to let it run very slow using only one or two really of parts
> at a time and work on small boards.   The RapRap type 3d printers
> don't cost much to build.  A pick and place is not much more than a 3d
> printer with a different nozzle.You can find people doing this on
> other email lists that deal with robots
>
> For most projects these SBCs (arduino, Pi 3, BBB,...) allow you to
> build almost anything without need of a custom PCB.
>
> On Thu, Jun 23, 2016 at 3:38 PM, Bob Stewart  wrote:
> > Thanks Bob et al,
> >
> > This is about what I expected, but I had to ask.  I wonder how long
> it'll take for that several thousand bucks for a pick-n-place machine to
> become a couple hundred?  That would be the final hurdle for the tiny
> electronics business.
>
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Measuring receiver...

[Graham / KE9H]

This is heavily used in cellular system security and cellular unit
identification and tracking.
Do a google search on patents using the the term "RF fingerprinting" and
you will get quite a few hits.  Mostly recent application to cellular
systems.  You might look at the prior art listings and see if they take you
back somewhere.  Although unlikely any classified methods were patented.

--- Graham

==

On Tue, Jun 21, 2016 at 4:02 PM, jimlux  wrote:

> On 6/21/16 11:28 AM, Brooke Clarke wrote:
>
>> Hi:
>>
>> During W.W.II there were secret methods of "fingerprinting" radio
>> transmitters and separately the operators.
>> I suspect the transmitter fingerprinting involved things like frequency
>> accuracy, stability, CW rise and decay time,  For the operator some
>> from of statistics on the timings associated with sending Morse Code.
>> But. . .  I haven't seen any papers describing this.  Can anyone point
>> me to a paper on this?
>>
>> For "human controlled" stuff, e.g. recognizing someone's "fist", there's
> a huge literature out there on biometric identification looking at things
> like keyboard and mouse click timing - the timing requirements are pretty
> slack, and hardly time-nuts level, unless you're looking to do it with
> mechanical devices constructed from spare twigs and strands of kelp.
>
> There have been a variety of schemes for recognizing individual radios by
> looking at the frequency vs time as they start up. Likewise, it's pretty
> easy to distinguish radar magnetrons from each other.  Not a lot of papers
> about this, but you'll see it in advertising literature, or occasionally in
> conference pubs (although I can't think of any off hand).  There was
> someone selling a repeater access control system that was based on the
> transmitter fingerprint.
>
> But the real reason why you don't see any publications is that this stuff
> is pretty classic signals intelligence (SIGINT or MASINT) and it is still
> being used, and is all classified. You're not relying on Betty the receiver
> operator to recognize the characteristic chirp as the agent's radio is
> keyed, it's all done by computer now, but the basic idea is the same.  And
> as with most of this stuff, the basics are well known, but the practical
> details are not, or, at least, are the proprietary secret sauce in any
> practical system. (In a significant understatement, Dixon, in "Spread
> Spectrum Systems" makes some comment about how synch acquisition is the
> difficult part and won't be described in the book)
>
> You might look at the unclassified proceedings of conferences like MILCOM
> and find something.  Googling with MASINT might also help.
>
>
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Re: [time-nuts] HF frequency counting receiver

[Graham / KE9H]

Most of the folks doing the FMT these days use some sort of audio
spectrum analyzer program and estimate the frequency using that.

Or use the audio spectrum analyzer to measure the difference between
the frequency being measured and the precision reference. You are
correct, it is usually not a classic counter.


You need a good reference to calibrate the frequency of your receiver -
depending on its design, you might just be able to measure your 10MHz
reference
to figure out the offset for your receiver, and if it's stable over the
time required, you're good to go.

Well, even if the synthesizer is GPSDO referenced and locked, a digital
synthesizer
will have a minimum step size or resolution that it can generate.
You might not be able to hear it with your ear, but it is there.
For instance a DDS based synthesizer with a 32 bit tuning word and a 200 MHz
sampling clock will have a step size of 46 milliHertz.
So when you enter a decimal frequency into the synthesizer, you get the
closest frequency it can generate, which can have an error of up to +/- 23
milliHertz. And the actual error versus frequency entered breaks into sort
of
a Moire pattern if you plot it.  The errors are deterministic, but a user
normally does not have the
information to figure them out.

The ionospheric Doppler will spread the signal a few tenths of a Hz,  YES.

so getting millihertz is more random luck of the draw. NO,
it is all about how good your averaging method/strategy is, over the period
of the test measurement.
A lot of the Doppler error can be averaged out.
Some of it is an actual net vertical movement of the reflection point, as
you said, worst at sunrise/sunset.

Look at the scores/accuracy for some of the recent frequency measurement
tests.

--- Graham

==

On Mon, Jun 20, 2016 at 12:16 PM, jimlux  wrote:

> On 6/20/16 7:51 AM, Nick Sayer via time-nuts wrote:
>
>> I'm considering taking a shot at the next ARRL frequency measurement
>> contest.
>>
>> The assumption going in is that the signal is CW, with at least a
>> half minute or so of just solid "on" at one point or another and that
>> reception is reasonably good.
>>
>> I've got a good TIA and excellent references, but that's the easy
>> part, it seems to me. It seems to me that what I really need to do is
>> make a synthesized heterodyne receiver that can present an accurately
>> tuned RF band pass - say, 10 kHz wide with the synthesizer set for 5
>> kHz steps - to the TIA, with some manually tunable high-pass and
>> low-pass filtering to isolate the signal of interest. If the mixer
>> got its LO from a synthesizer with a GPSDO reference, it seems to me
>> that you could then measure the frequency of the signal of interest
>> (now an audio frequency, so you can listen to it too) with the TIA
>> (also getting the GPSDO reference) and then do simple math to arrive
>> at the actual RF frequency.
>>
>> Anybody have any thoughts?
>>
>>
> Most of the folks doing the FMT these days use some sort of audio
> spectrum analyzer program and estimate the frequency using that.
>
>
> The signal isn't very high SNR (unless you're in Newington and they are
> radiating from W1AW) - I'm not sure a narrow band filter followed by
> a counter would be the best way to go.
>
> You need a good reference to calibrate the frequency of your receiver -
> depending on its design, you might just be able to measure your 10MHz
> reference to figure out the offset for your receiver, and if it's stable
> over the time required, you're good to go.
>
> The ionospheric Doppler will spread the signal a few tenths of a Hz, so
> getting millihertz is more random luck of the draw.
>
>
> I note also that the last ARRL FMT ran at 10PM EDT with a transmitter in
> California (where it was 7PM).. this is a particularly BAD time of day to
> do the test, because the ionosphere is changing effective height and
> attenuation so it greatly penalizes folks who are relying on skywave
> propagation.
>
> You can practice using WWV/WWVH, by the way.. nice AM signal with a good
> carrier.
>
>
>
>
>
>
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Re: [time-nuts] HF frequency counting receiver

[Graham / KE9H]

You need to be able to measure frequency accurately in the milli-Hertz
range to be competitive in the frequency measuring contests.

I doubt the Selective Voltmeters have that level of resolution. I think
they 'only' read to 0.1 Hz.

--- Graham



On Mon, Jun 20, 2016 at 11:52 AM, Pete Lancashire 
wrote:

> Never tried it but a Selective Level Meter aka HP 3586A/B/C ?
>
> On Mon, Jun 20, 2016 at 7:51 AM, Nick Sayer via time-nuts
>  wrote:
> > I'm considering taking a shot at the next ARRL frequency measurement
> contest.
> >
> > The assumption going in is that the signal is CW, with at least a half
> minute or so of just solid "on" at one point or another and that reception
> is reasonably good.
> >
> > I've got a good TIA and excellent references, but that's the easy part,
> it seems to me. It seems to me that what I really need to do is make a
> synthesized heterodyne receiver that can present an accurately tuned RF
> band pass - say, 10 kHz wide with the synthesizer set for
> > 5 kHz steps - to the TIA, with some manually tunable high-pass and
> low-pass filtering to isolate the signal of interest. If the mixer got its
> LO from a synthesizer with a GPSDO reference, it seems to me that you could
> then measure the frequency of the signal of interest (now an audio
> frequency, so you can listen to it too) with the TIA (also getting the
> GPSDO reference) and then do simple math to arrive at the actual RF
> frequency.
> >
> > Anybody have any thoughts?
> >
> >
> > Sent from my iPhone
> > ___
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Re: [time-nuts] HF frequency counting receiver

[Graham / KE9H]

Nick:

You can do it this way, but it requires you to totally understand the
mathematics and granularity of ALL of the frequency sources and
synthesizers in the superhet receiver.
And if there are any audio soundcards or sampling devices involved, the
specifications and origin of the sampling clocks.  If it is the USB clock
in your computer, you can be pretty much screwed right there.

These are generally not published by the manufacturers, so you will need a
friend at the manufacturer to provide you this information. Or be ready to
do a lot of reverse engineering.

The typical RF frequency measurement system for off-the-air measurement
only uses the superhet for signal reception, then adds a precision (GPSDO
derived) local oscillator/signal source for which you totally understand
the mathematics and granularity, because you built it yourself, and an
audio counter that allows you to measure the audio difference between the
signal to be measured, and the local precision reference that you inject.
In this system, the absolute frequency of the superhet receiver is a "don't
care".  You just want to measure the difference between the signal to be
measured and your local precision reference.

--- Graham

==

On Mon, Jun 20, 2016 at 9:51 AM, Nick Sayer via time-nuts <
time-nuts@febo.com> wrote:

> I'm considering taking a shot at the next ARRL frequency measurement
> contest.
>
> The assumption going in is that the signal is CW, with at least a half
> minute or so of just solid "on" at one point or another and that reception
> is reasonably good.
>
> I've got a good TIA and excellent references, but that's the easy part, it
> seems to me. It seems to me that what I really need to do is make a
> synthesized heterodyne receiver that can present an accurately tuned RF
> band pass - say, 10 kHz wide with the synthesizer set for
> 5 kHz steps - to the TIA, with some manually tunable high-pass and
> low-pass filtering to isolate the signal of interest. If the mixer got its
> LO from a synthesizer with a GPSDO reference, it seems to me that you could
> then measure the frequency of the signal of interest (now an audio
> frequency, so you can listen to it too) with the TIA (also getting the
> GPSDO reference) and then do simple math to arrive at the actual RF
> frequency.
>
> Anybody have any thoughts?
>
>
> Sent from my iPhone
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Re: [time-nuts] Simple solution for disciplining OCXO with 1 PPS

[Graham / KE9H]

If you want an "existence proof" for a simple, mostly analog, a few digital
counters, no software or microprocessor GPSDO, look at the "Miller" GPSDO.
He designed it for his own use, then put it into production because of
demand for a simple, cheap GPSDO.  It has been characterized, and works
well for the simple circuit.

The schematics are published, since it started as a hobby project.

http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm

http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm

You can buy his, or build your own with his design as a starting point.

He does use a GPS with 10 kHz output to simplify some of the timing and
integration issues Bob referred to.

--- Graham

==



On Mon, May 23, 2016 at 8:21 PM, Bob Camp  wrote:

> Hi
>
> Ok, so how would you do a pure analog GPSDO?
>
> The GPS receiver and that side of it are what they are. I’ll assume that
> you have a 1 pps out of a module.
>
> Your OCXO needs to get to 1 Hz via dividers. You can do that with digital
> dividers or with a chain of regenerative
> dividers. One is a bit more analog, the other may be “ok” under the “don’t
> go to crazy” ground rule.
>
> You now have a PPS that is off somewhere relative to the GPS. A push
> button will get them into rough alignment.
> Your OCXO is quite likely a bit high or low. A multi turn pot on the EFC
> will let you get it within 1x10^-9 without a
> lot of crazy work. A reasonable counter tied to a reference will let you
> do this.
>
> Net result: The pps signals are roughly aligned and drifting < 1 ns / s.
> Considering the delta between them is
> bopping around by 10 ns, that’s quite good.
>
> Run a very normal bipolar charge pump off of the delta between the two pps
> signals. Fire a sample and hold when
> the transition is over. You now have a (maybe) +/- 60V signal that
> corresponds to the phase error. Since you are using
> film capacitors, the 60V comes along for free. Taking it to the maximum is
> just a way to save money on caps.
>
> Next up, do a fairly simple 20 second time constant R/C filter. That will
> take out a lot of the hopping around and make
> the rest of the system a bit easier to quiet down. You now have a somewhat
> linear +/- 60V signal that tells you how
> far off phase the setup is. After the RC you have a high input impedance /
> low drift buffer amplifier. Yes that’s a little
> tricky.
>
> Next you need a P and an I term. Both need to be variable as the system
> calms down. A rotary switch will do fine for
> this. Relays might also do the job. The P is a bank of resistors, each one
> to scale the buffered R/C to your control amp.
> The I goes off to a similar set of resistors driving an integrator. Net
> time constant there will be in the 200 to 2,000 second range.
> That’s were the ovenized caps come in. You also need a really good amp as
> part of the integrator to buffer out the signal.
>
> The nice thing about doing it this way is that you can *see* it all
> happening. There is a nice *clunk* noise as the filter
> steps off. Each number in the filter has a (likely large value) resistor
> that sets it up. To change the filter characteristics,
> you swap out resistors or twiddle pots.
>
> If you do the math, even with 60 V on the system, you probably don’t want
> anything over 1 meg ohm involved. At 2K seconds
> that gets you to a pretty big film capacitor bank. Even the 20 second
> lowpass isn’t exactly small by the standards of fancy
> capacitors.
>
> There are a few interesting tidbits like wire wound / high value / low
> temp co resistors that would help things a bit. Swapping
> those in and out as you change filter settings experimentally could get a
> bit crazy.
>
> The net result should be a good starting point for a GPSDO. You still
> would need to spend all of the time working out values
> and matching it up to your OCXO. The need for a good local reference and
> good measurement gear while doing this still is
> a limit, just like the pure digital approach.
>
> Bob
>
>
>
> > On May 23, 2016, at 12:46 PM, Nick Sayer via time-nuts <
> time-nuts@febo.com> wrote:
> >
> >
> >>
> >>> If that sounds too weird, I am open to receive advises for a
> microcontroller based solution.
> >>
> >> If you want to go that way, probably the simplest solution would be to
> >> take one of Nick Sayers boards, pull out the GPS receiver and feed the
> >> PPS input from your GPS receiver.
> >
> > It’d be kind of an awkward fit. For the OCXO/TCXO, you’d need to pull
> the oscillator as well as the GPS (I believe you said you had an oscillator
> already), and your EFC would be 1.65 volts wide centered on 1.65 volts.
> That’s unlikely to be absolutely correct for your oscillator. You could
> change around the Vref for the DAC, but at that point I’d consider
> redesigning the board for your purposes instead.
> >
> > That said, I think it’d be easy to adapt the circuit and code for a more
> arbitrary setup. And I believe my system is good down to the 

Re: [time-nuts] AM335x/Beaglebone Black memory bus (was: 1 PPS 50-ohm driver)

[Graham / KE9H]

I think the more common way to do this is SPI or the I2S / DSP type
transfer formats.
You are likely to find existing Verilog modules that do these transfer
formats.

--- Graham / KE9H

==

On Mon, Apr 18, 2016 at 2:10 AM, Attila Kinali <att...@kinali.ch> wrote:

> On Sun, 17 Apr 2016 23:03:11 +0200
> Gerhard Hoffmann <dk...@arcor.de> wrote:
>
> > BTW:
> > Is there a way on the BeagleBoneBlack to map the IO-Pins like an ancient
> > data bus? some addresses, data, read, write or so? Something to get into
> > an FPGA without much ado, with medium-speed data rates?
>
> Yes, you can use the GPMC subsystem for this. Have a look at the TRM
> and Documentation/devicetree/bindings/bus/ti-gpmc.txt.
> I'm sure there are also some examples of DT bindings out there.
> If you have trouble getting it working, you can ask in #beagle@freenode.
>
> Attila Kinali
>
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neil Stephenson
> ___
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Re: [time-nuts] Building a mains frequency monitor

[Graham / KE9H]

For all you Powerline Time nuts, and maybe GPSDO time nuts, too.

Consider this new PIC.PIC16F1619
$1.60 USD, quantity one at Mouser.

It was designed to be an AC motor controller.

So has some interesting built in hardware peripherals:
Mains Zero crossing detector.
Runs up to 32 MHz master clock, which says you could time stamp with 8
MHz resolution. ~125 ns.
Hardware PID engine and Math Accelerator.
CRC engine
Band gap voltage reference
Configurable Logic Cell (for small amount of custom logic.)
Angular Timer
Signal Measurement Timer

Plus all the other normal PIC stuff: A->D, D->A, PWM, multiple other
timers,
comparators, serial, SPI and I2C communications.

I think the Angular Timer and/or Signal Measurement Timer hardware
peripherals
could be used as high accuracy 1 PPS phase detectors for GPSDO.

--- Graham

==

On Tue, Apr 12, 2016 at 7:25 AM, Tom Van Baak  wrote:

> Hi Hal,
>
> > What do you mean by a double wide cycle?
> > What do you mean by a missed cycle?
> > They seem like the same thing - if you miss one, the next one will be
> twice as wide.
>
> Yes, sorry, I mixed up my words there. A missed cycle would be a reading
> that looks closer to 32 ms than 16 ms. And a double cycle is one where, for
> example, the negative zero crossing confuses the ZCD and you get two
> readings that each look like 8 ms instead of one at 16 ms. Or if there's
> noise you might get 2 ms and 14 ms, or 0.1 ms and 16.5 ms, etc. I've seen
> period counters where you get cycle slips as a result.
>
> This effect is especially bad in 1970's era mains clocks where they would
> keep time by counting mains cycles. That's a case where signal conditioning
> is important.
>
> Similar problems occur with a TIC when you use a GPS 1PPS as start and DUT
> 1PPS as stop. You can get into awkward situations where each reading takes
> 2 seconds instead of 1 second.
>
> With a time-stamping counter every reading essentially includes the full
> history of phase, so missing or extra data doesn't change the net result.
> At worst you use a "picket fence" model to clean up the raw data.
>
> By the way, a cool thing you can do with a mains time-stamping counter is
> check the polarity of your AC outlets. You can go around the house with a
> battery operated timestamping counter and depending on which way you orient
> the plug or which 120-0-120 leg your outlet is on, you get 8 ms shifts in
> the time stamps.
>
> > I agree that working with time stamps seems simpler.  I wonder if that's
> > because I got started that way and/or wanted to watch phase drift?  I'll
> bet
> > durations work just as well if the data collection code remembers the
> round
> > off and includes it in the calculations for the next cycle.
>
> Correct, a data set of phase (or timestamps) and a data set of intervals
> (or duration, or period, or frequency) are mathematically equivalent and
> you can freely convert from one to the other, plus a constant.
>
> You have to watch out for floating-point data formats, where you can loose
> precision if you are not careful, due to rounding or range. This is
> especially true for data files of frequency; that 1/period calculation can
> result in accumulation of error.
>
> > To me, this is the important advantage of working with time stamps, but
> > that's because I was interested in tracking phase which turns into clock
> > error.
>
> Right. You and I both record phase because we're treating mains as a
> clock. But I think other people are more interested to see strip charts of
> frequency over time, or histograms of frequency deviation and the like. In
> that case, the occasional bad data or cycle slip is not a problem. Another
> way to put it -- being a time nut is always harder than being a frequency
> nut.
>
> /tvb
>
> - Original Message -
> From: "Hal Murray" 
> To: "Tom Van Baak" ; "Discussion of precise time and
> frequency measurement" 
> Cc: 
> Sent: Monday, April 11, 2016 7:04 PM
> Subject: Re: [time-nuts] Building a mains frequency monitor
>
>
> >> record the duration of each cycle directly
> >> 5) Double wide cycles are detectable but missed cycles are not.
> >
> > What do you mean by a double wide cycle?
> > What do you mean by a missed cycle?
> > They seem like the same thing - if you miss one, the next one will be
> twice
> > as wide.
> >
> >> Here are the advantages of the timestamping method:
> >> 5) Extra or missing cycles are easy to detect and repair with no loss of
> >> phase information.
> >
> > I'd expect the extra or missing cycles would be easy to spot if you were
> > looking at the duration.  The duration would either be twice normal or
> less
> > than half of normal.  In the latter case, you have to figure out which
> is the
> > extra pulse.
> >
> > I agree that working with time stamps seems simpler.  I wonder if that's
> > because I got started 

Re: [time-nuts] Advise on building a DIY GPSDO?

[Graham / KE9H]

The lowest jitter way to do this kind of conversion is to multiply the
signal up to some common multiple frequency, then divide it back down to
where you want to be.  For instance, with 8 or 24 MHz, multiply up to 240
MHz, then divide by 24 to get 10 MHz.

Modern clock generator chips have this capability built in.  As an example,
the TI LMK04100 series clock chip.  It actually has an on-board 1200 MHz
VCO, and all the phase-lock loop hardware to multiply up, and, and five
different divider chains, so you can get up to five different output
frequencies as long as the math works out.  Everything is constrained to
integer multiples and integer division, so there is none of the dithering
discussed above.  But you have a lot of integer options when the common
multiple is up at 1200 MHz. Much lower sidebands and phase noise.  Also the
ability to add a crystal VCO as a clean-up filter loop if your input
reference is dirty to begin with.

In my application, I am looking at taking a 10 MHz Oven-VCXO input and
putting out both a 24 MHz clock for the master clock of a BeagleBone Black,
and 480 kHz for a Shera style control loop for GPS disciplining.

--- Graham

==

On Fri, Apr 8, 2016 at 5:13 PM, Bob Camp  wrote:

> Hi
>
> If you start from a 24 MHz TCXO (different modules use different TCXO’s):
>
> On an 8 MHz output, most of the time you divide by three.
>
> On a 10 MHz output, you need to divide by 2.4. The net result is that you
> divide by 2 sometimes and 3 other times.
>
> In the 10 MHz case, there is a *lot* of energy at 12 MHz and 8 MHz, along
> with
> the 10 MHz output.
>
> In the 8 MHz case, most of the RF energy is at 8 MHz.
>
> 
>
> To correct the output by 1 ppm on the 8 MHz output, you need to either
> drop or
> add one pulse out of every million pulses. Effectively you divide the 24
> MHz by
> 2 or by 4 when you do that. You get a bit of 12 MHz or a bit of 6 MHz as a
> result.
> That can be filtered out with a RF filter. The same is true with a
> (somewhat more
> complex) filter on the 10 MHz output.
>
> In addition to the “big” RF spurs, you get a low frequency component to
> the output
> modulation. You are “phase hitting” the output eight times a second. That
> gives you
> an 8 Hz sideband along with the further removed stuff. Since it’s not
> simple / clean
> phase modulation, there are more sidebands than just the few mentioned
> above.
>
> What messes things up even more is that you never are quite doing one ppm.
> You are doing
> corrections like 0.12356 ppm this second and 0.120201 ppm the next second.
> The pattern of pulse drop and add is not as simple as you might hope. The
> low
> frequency part of the jitter (and it will be there) is no different than
> the noise on
> a 1 pps output. You still need to do very long time constant (or very
> narrow band)
> filtering to take it out.
>
> Bob
>
> > On Apr 8, 2016, at 7:06 AM, Herbert Poetzl  wrote:
> >
> > On Mon, Apr 04, 2016 at 06:07:54PM -0700, Alexander Pummer wrote:
> >> and it is relative easy to make 10MHz from 8MHz with analog
> >> frequency manipulation, which generates less jitter
> >
> > Could you elaborate on this a little if time permits?
> > I'm more a 'digital person' but it sounds interesting.
> >
> > Thanks in advance,
> > Herbert
> >
> >> 73
> >
> >> On 4/4/2016 4:27 PM, Attila Kinali wrote:
> >>> On Mon, 4 Apr 2016 17:56:29 -0400
> >>> Bob Camp  wrote:
> >
>  The variable frequency output on the uBlox (and other) GPS
>  receivers has come up many times in the past.
> >
>  If you dig into the archives you can find quite a bit of
>  data on the (lack of) performance of the high(er) frequency
>  outputs from the various GPS modules. They all depend on
>  cycle add / drop at the frequency of their free running TCXO.
>  Regardless of the output frequency, that will put a *lot* of
>  jitter into the output.
> >>> That's why you should put the output frequency of the ublox modules
> >>> to an integer divisor of 24MHz. Ie 8MHz works but not 10MHz.
> >
> >>> Attila Kinali
> >
> >
> >> ___
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Re: [time-nuts] Microsonics TCXO

[Graham / KE9H]

Joe:

In that time frame, there were a lot of "simulcast" analog radio, police,
pager,
and TV systems, where different broadcast transmitter locations transmitted
the
same information on the same frequencies.  The goal was to have strong
signals
across a large (overlapping) combined coverage area.

For the systems to work with minimum interference in the RF signal overlap
zones, the transmitters needed to be at slight, but precision offsets.
These
could have been master oscillators for those systems.

An even better solution would have been to put them on the 'exact' same
frequency and phase, but the digital electronics and GPS frequency/timing
systems that could enable that, had not been deployed yet.

1979 ::   No PC's, no cell systems deployed, microprocessors were eight bit,
with clock speeds below 10 MHz, communication systems were mostly analog.
Long time ago according to Moore's Law.

https://upload.wikimedia.org/wikipedia/commons/0/00/Transistor_Count_and_Moore's_Law_-_2011.svg

--- Graham / KE9H

==

On Sun, Mar 20, 2016 at 12:42 AM, Joseph Gray <jg...@zianet.com> wrote:

> I got my hands on some of these.
>
> https://dl.dropboxusercontent.com/u/19599147/TCXO%20Top.jpg
>
> https://dl.dropboxusercontent.com/u/19599147/TCXO%20Bottom.jpg
>
> A search finds other Microsonics units, but not this one. I can't find
> any information on what voltage to feed this. Does anyone know?
>
> I know that these aren't Time Nuts grade, but I am curious to see how
> good/bad they are. They look to be NOS from 1979.
>
> Some of the other samples are marked as being set to anywhere from 1
> Hz to 7 Hz high or low. Why would they have been factory adjusted high
> or low?
>
>
> Joe Gray
> W5JG
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Graham / KE9H]

Rob:
Are you sure you were running it with a clean power supply?
Any 60 Hz ripple on the supply could show up as AM/PM modulation.
You might want to try another 5V power supply before you give up on the
oscillator.
--- Graham


On Sat, Feb 27, 2016 at 11:35 AM, Rob Sherwood.  wrote:

> Hi Dan,
>
> I purchased two of these, and VA7OJ one.  One of mine is defective, and
> the seller is going to replace it.  What was disappointing was all the
> spurious at 60 Hz intervals relatively close-in to the 10 MHz carrier.  I
> suppose if all one wants is a reasonably accurate 10 MHz, then they work
> OK.  My good one and Adam's unit were 1x10^7 low in frequency once warmed
> up, and there are pins for frequency adjustment and sync to another
> standard.  However if one wanted it for an oscillator with good close-in
> phase noise, the spurs ruin that hope.
>
> Do you know if there is a chopper at 60 Hz that runs the proportional oven
> that is the source of all the spurious?
>
> Rob
> NC0B
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Daniel
> Watson
> Sent: Saturday, February 27, 2016 9:48 AM
> To: time-nuts@febo.com
> Subject: [time-nuts] Inside a CTS 1960017 OCXO
>
>
>
> Hi,
>
> I'm sure many of you are tracking the cheap CTS 10MHz OCXOs available on
> eBay right now. I purchased a case of them, and decided to crack one open.
> I took pictures along the way, thinking that might be interesting to the
> list. Here is the blog post if you are interested:
>
>
> http://syncchannel.blogspot.com/2016/02/10mhz-ocxo-teardown-cts-1960017.html
>
> Comments on the internal construction of the OCXO are welcome. It seems
> pretty straightforward inside though.
>
>
> Best regards,
>
> Dan W.
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>
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Graham / KE9H]

Dan:

Thanks for photo documenting the tear down of the CTS oven oscillators.
I bought a few, and was interested in what was inside.
I was surprised to see an HC-6 style crystal, but at least it was a
cold-weld case.

I note that you did some design work for Adafruit.
Curiosity question:
Did they solicit you, or did you solicit them for the work?
Or did they just see and copy your stuff on Oshpark?

--- Graham / KE9H

On Sat, Feb 27, 2016 at 10:48 AM, Daniel Watson <watsondani...@gmail.com>
wrote:

> Hi,
>
> I'm sure many of you are tracking the cheap CTS 10MHz OCXOs available on
> eBay right now. I purchased a case of them, and decided to crack one open.
> I took pictures along the way, thinking that might be interesting to the
> list. Here is the blog post if you are interested:
>
>
> http://syncchannel.blogspot.com/2016/02/10mhz-ocxo-teardown-cts-1960017.html
>
> Comments on the internal construction of the OCXO are welcome. It seems
> pretty straightforward inside though.
>
>
> Best regards,
>
> Dan W.
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Re: [time-nuts] Z3801 Newbie Question

[Graham / KE9H]

Dave:

Your antenna setup sounds reasonable.
You might want to try dropping your elevation mask down to 5 or 10 degrees,
as an experiment.

Things that cause the sporadic jumps could be certain satellites being
added to, or removed from the solution.
Also, if there are particular angles/directions where you receive the
satellite signal as a reflection, rather than a direct signal, you get
position errors that move into and out of your solution.  If the satellite
is behind one of your trees, and the received signal bouncing off the other
tree is temporarily stronger, you have a temporary path length/position
change.

--- Graham

==

On Fri, Jan 29, 2016 at 3:54 AM, Artek Manuals <manu...@artekmanuals.com>
wrote:

> Graham
> Symmetricom 58532A antenna, just above the roof, with 8 feet of RG213.
>
> Flat ( Florida) rural location with 360 degree view other than some trees.
> The GPS Antenna plot from Z38xx has filled in pretty much 360 degrees down
> to 20 degrees solid and in most directions to down to 15 degrees elevation.
> The exception of course is the polar abyss to the north. I am going to
> lower the elevation angle for a while just to see if there is any difference
>
> Looking at the link sent to me earlier
> http://www.realhamradio.com/GPS_websites_list.htm . I am seeing the same
> phenomena on most all oft the plots for the Z3801 around the world, So I
> assume that my unit is :behaving normally" for a Z3801A ... Just cant
> explain why all of us see a sporadic jumps in PPS error for an hour or two
> once or twice a day
>
> Dave
> NR1DX
> ArtekManuals.com
>
> A man with a watch always knows what time it is
> A man with two watches is never quite sure
>
> . On 1/28/2016 6:23 PM, Graham / KE9H wrote:
>
> Please describe your Antenna setup and location.
>> How much of the sky can it see, in which directions.
>> Which directions are blocked for direct line of sight, and must depend on
>> reflections from nearby buildings or objects?
>>
>> --- Graham
>>
>>
>> And here is the question is the sudden jump in the pps deviation due to
>> ionospheric and the satellite constellation change? IS there anything I can
>> do to minimize it (or is it even necessary to worry/ wonder about)  This
>> behavior has going on since the beginning so it is not likely related to
>> events earlier in the week. But that set me to wondering could I minimize
>> it by say raising the elevation mask? Are there satellites in the
>> constellation that are notorious for noise etc  that could be excluded from
>> the tracking list ...etc etc
>>
>>> Dave
>>>> NR1DX
>>>> ArtekManuals.com
>>>>
>>>> A man with a watch always knows what time it is
>>>> A man with two watches is never quite sure
>>>>
>>>>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
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Re: [time-nuts] Z3801 Newbie Question

[Graham / KE9H]

Please describe your Antenna setup and location.
How much of the sky can it see, in which directions.
Which directions are blocked for direct line of sight, and must depend on
reflections from nearby buildings or objects?

--- Graham

==

On Thu, Jan 28, 2016 at 11:25 AM, Tom Van Baak  wrote:

> Dave,
>
> Plot the #SV tracked and signal strength(s) over a couple of days. See if
> your once or twice a day glitches correlate to periods of low reception.
>
> To see what the reception of other z3801a owners look like:
>
> http://www.realhamradio.com/GPS_websites_list.htm
>
> You may even want to try a lower mask instead of a higher mask. It's a
> trade-off between fewer SV with solid reception and more SV with possibly
> spotty reception.
>
> Easy experiment: try 0 degrees for two days, then 15 degrees, then 30
> degrees.
>
> What I do is issue a syst:stat? command every 30 seconds. It's easy then
> to go back to the log files and check things like constellation changes and
> elevation, or brief or prolonged periods of holdover, etc.
>
> /tvb
>
> > On Jan 28, 2016, at 8:49 AM, Artek Manuals 
> wrote:
> >
> > OK
> >
> > My Z3801A came out of mothballs after 15 years in controlled storage and
> appears to be behaving. now I am curious as to what I am seeing
> >
> > First I am not truly a "time" nut ( I am semi retired and have not worn
> a watch since October 12th 2008 :-) ). I am probably more of "frequency"
> nut . I use the Z3801A as my 10MHz reference. Having a reference source
> that is good to .1Hz at 10MHz is more than adequate as a reference for my
> counters, signal generators and and spectrum analyzers. But like all
> engineers if you give me the numbers I an drawn to trying to figure out
> what they are telling me.
> >
> > My Z3801A has been on for about 2 weeks now and typically reports 1PPS
> +/- 20ns readings 20 hours/day. Then all of a sudden once or twice a day it
> will go nuts and the variation increases to +/- 80ns for an hour or two
> before settling back down. Watching the 10mhz on a 10 digit counter shows
> no short term change in the frequency of the OCXO when the thing goes nuts
> there are slight changes in EFC but nothing dramatic vs any other hour to
> hour variation. The Allen and modified Allen deviation is around 2e-13 as
> it approaches 1e5 samples
> >
> > Here is the setup
> > 1) Z3801A
> > 2) Symmetricom 58532A antenna, just above the roof, with 8 feet of RG213
> to the Z3801A
> > 3) Running on a lab grade power supply at 48.5 volts (voltage variation
> over time is less .05 volts)
> > 4) Lab runs at 73deg F +/- 2 degrees , humidity is NOT closely controlled
> > 5) Running Z38xx software
> > 6) Elevation cutoff on satellites is set for 15 degrees
> >
> > And here is the question is the sudden jump in the pps deviation due to
> ionospheric and the satellite constellation change? IS there anything I can
> do to minimize it (or is it even necessary to worry/ wonder about)  This
> behavior has going on since the beginning so it is not likely related to
> events earlier in the week. But that set me to wondering could I minimize
> it by say raising the elevation mask? Are there satellites in the
> constellation that are notorious for noise etc  that could be excluded from
> the tracking list ...etc etc
> >
> > Dave
> > NR1DX
> > ArtekManuals.com
> >
> > A man with a watch always knows what time it is
> > A man with two watches is never quite sure
> >
> > --
> > Dave
> > manu...@artekmanuals.com
> > www.ArtekManuals.com
> >
> >
> > ---
> > This email has been checked for viruses by Avast antivirus software.
> > https://www.avast.com/antivirus
> >
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Re: [time-nuts] low noise multiplication to 100 MHz

[Graham / KE9H]

There are clock distribution parts designed to do this low noise frequency
conversion and distribution.

Consider TI  LMK04100

Ignore PLL1
Put your 10 MHz as the reference input to PLL2.
Set Internal VCO to ~1200 MHz
Set the internal dividers to get 100 MHz out, and 10 MHz back to the PLL2
phase detector.

Get reasonable noise and 100 MHz output with your choice of 2VPECL, LVDS,
LVCMOS output levels.

If you have a dirty input clock/reference, or multiple sources, you can use
PLL1 and an external crystal in a VCO to clean it up before you multiply it
to 1200 MHz.

And you can get up to four other frequencies out of the part at the same
time.

150 fs class jitter.

$13 cost, quantity one.

--- Graham

==





On Mon, Jan 25, 2016 at 9:22 AM, Bert Kehren via time-nuts <
time-nuts@febo.com> wrote:

> If not good enough an XOR with filter and one of the Crystek VCXO's
> previously mentioned may do it.
> Bert Kehren
>
>
> In a message dated 1/25/2016 10:01:33 A.M. Eastern Standard Time,
> mag...@rubidium.dyndns.org writes:
>
> Also, it  will be systematic, with idle tones. Because of the delay
> elements used,  they will not be long-term static but move around.
>
> I agree, this is  quite noisy. If the noise is tolerable, it is indeed a
> small solution. 100  ps 1-sigma for 5 MHz in 100 MHz out isn't what I
> would consider  low.
>
> https://www.idt.com/document/dst/570-datasheet
>
> Cheers,
> Magnus
>
> On  01/24/2016 11:12 PM, Bruce Griffiths wrote:
> > Unfortunately the ICS570  (like all zero delay buffers) has an output
> jitter approaching about 1000  times the likely RF ADC internal sampling
> jitter. The resultant SNR  degradation may be a little excessive for this
> application..
> >  Bruce
> >
> >
> >  On Monday, 25 January 2016  11:00 AM, Bert Kehren via time-nuts
>   wrote:
> >
> >
> >   With all the discussions in a small  100 MHz source I asked my project
> > partner Juerg in Switzerland to run  some data on the ICS 570 that we use
> on the
> > majority of our projects  with excellent results. Using the HP53132A we
> see
>
> > + - 1   count at E10-11 ignore the large jumps those come from the Tbolt
> >  frequency  change to correct the 1 pps. Depending on the application
> this  is an
> > excellent  device.
> > Bert  Kehren
> >
> >
> > In a message dated 1/23/2016 6:02:23 P.M.  Eastern Standard Time,
> > dk...@arcor.de writes:
> >
> > Am   22.01.2016 um 22:40 schrieb jimlux:
> >> the oscillator is a HCMOS  output,  so figure swinging about 3.5V
> >> Output.. I'm feeding  differential clock  inputs on ADCs.  I'll bet a
> >> +/-  300mV swing would  work.
> >>
> >>> 4)Title said "Low  Noise"  needs better  definition as to what kind of
> >>>  noise and how far down. Are we to  be  concerned about harmonic and
> spur
> >>> content as compared to  real random white  noise?
> >>
> >> This is time-nuts.. it has to be   perfect..
> >>
> >> But realistically, my source is probably  going to be  about -90dBc/Hz
> >> at 1 Hz, -125 at 10Hz, -145 at  100 Hz.  I'm  going up by a factor of
> >> 10, so I'd expect  20 dB worse plus a  little..(nothing is perfect,
> eh?)
> >>
> >> Call it maybe -100 to -95 at  10 Hz, -125 to  -120 at 100 Hz and so
> forth.
> >>
> >> harmonics are   interesting: it's the sample clock into an ADC. So
> >> harmonics of  the  100 aren't a big deal.  harmonics of the 10 or 20
> >>  are.  If  you have significant 90 or 110 contaminating the 100,  then
> >> you get  weird spurs..  (I had this problem on a  software radio where
> >> the  50 MHz sample clock was  contaminated with some 66 MHz from the
> CPU)
> >>
> >>  Spurs cause the same issues.
> >>
> >> ON the other   hand... spurs that are pretty low don't make much
> >> difference  if  you're digitizing a signal that is close to the noise
> >>  floor: the spur  multiplied by the desired signal is usually lower  and
> >> down in the  noise.  Strong CW in band signals,  though, are a real
> pain.
> >>
> >>
> > <
> >
>
> https://picasaweb.google.com/103357048842463945642/Tronix#607927018804883377
> >  8
> >>
> >
> > I think that top left board would not be far  away:
> >
> > in :  10 MHz LVDS or CMOS
> > in:   3V3
> > out: 100 MHz CMOS 3V3
> >
> > just a  few hours wall  clock time from layout to working as a
> > ham radio weekender,  so  please excuse my diy home board
> > production process.
> >
> >  Ok, the use  of a 4046 descendant may not be the last word
> > from a  timenut perspective,  but I'll redo it with an osc of
> > my own  anyway. Divider 100/10 is a LVC163  (161?) +  lvc04.
> >
> >
> > <   http://www.crystek.com/crystal/spec-sheets/vcxo/CVHD-950.pdf   >
> >
> > Digi-Key has 153 of them on a tape and  441 of a  similar one  , even
> > cheaper that seems to point to the same data  sheet.
> >
> > <
> >
>
> http://www.digikey.de/product-detail/de/CVHD-950-100.000/744-1213-ND/1644128
> >
> >>
> >  You can get the few dB missing close-in by transfer from your
> reference.
> >
> > In the picture:
> > The 

Re: [time-nuts] PRS10 C900 replacement

[Graham / KE9H]

You will need to know the capacitance value.  Usually expressed in uF
(micro Farad).
Then some idea of the physical size, so the replacement will fit in the
current space.
--- Graham

==

On Tue, Jan 19, 2016 at 4:21 PM, davidh  wrote:

> Hi All,
>
> While still appearing to function normally, my PRS10 started to smell:
> C900 in the lamp assembly has self destructed.
>
> The SRS parts manual merely says "Capacitor, Tantalum, 35V, 20%, Rad", so
> I'd appreciate any advice on what additional parameters I should be looking
> at in selecting a replacement.
>
> Thanks,
>
> david
>
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Re: [time-nuts] Generating a solid PPS from 10Mhz source

[Graham / KE9H]

The programmable PIC or AVR or ... chip that will do the job are same or
less than a 555 chip, and a lot more flexible.
--- Graham

On Fri, Jan 15, 2016 at 11:55 AM, Adrian Godwin  wrote:

> Why use a board full of TTL when an $1 8-pin chip will do it ?
>
>
> On Thu, Jan 14, 2016 at 11:44 PM, Morris Odell 
> wrote:
>
> > Am I missing something here?
> >
> > I understand the ease and fun of programming up an AVR as much as anyone
> > but surely this task could be accomplished  easily with a chain of fast
> > synchronous TTL or CMOS dividers. A resynchronising FF could also be
> added
> > at the end to  clean up the 1 pps if required. You wouldn't need to worry
> > about the maths or OBOBs either.
> >
> > Admittedly you would need more PCB real estate but that shouldn't be a
> big
> > deal in most cases.
> >
> > Morris
> >
> >
> >
> >>> If anyone is interested in the equivalent functionality using an
> >>> ATTiny25 (for instance, if you’re already heavily invested in AVR
> instead
> >>> of PIC, like I am), ping me. I’ve privately written code to solve
> almost
> >>> the same problem and it could easily be adapted into doing the same
> job.
> >>>
> >>>
> >
> > Is there an easy circuit to build that can consistently deliver a 1
> > PPS from a 10MHz source with excellent resolution and
> repeatability?  My
> > first application is to test different 10MHz oscillators without a
> TIC
> > always attached and then compare the PPS output change over time
> against a
> > master GPSDO PPS with an HP53132A.
> >
> > The circuit used for PPS generation would have to deliver consistent
> > PPS output with preferably not more than 100ps noise or jitter,
> assuming a
> > perfect source.  I'm totally guessing that for this resolution, the
> PPS
> > would have to be generated and accurate to within 0.001Hz every
> second.  If
> > this is too difficult, maybe the integration time can be increased to
> > generate one pulse every 10second or every 100,000,000.00 cycles?
> >
> 
> >
> > ___
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> > and follow the instructions there.
> >
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Re: [time-nuts] beaglebone black, debian, NTP client

[Graham / KE9H]

The Debian 8.x (jessie) releases for the BeagleBone run systemd-timesyncd,
which is installed and on by default. As long as the Beaglebone is hooked
to the internet, it has correct time to +/- 10 milliseconds or so.
Probably good enough for a time-nut lawn sprinkler.

systemd-timesyncd is a simplified system that corrects the system clock in
the computer using NTP, but only as a client. The Beaglebone does not
participate as a peer.

For Debian 7 (wheesie), I think you need to install and enable ntpd.



On Thu, Dec 31, 2015 at 7:27 PM, jimlux  wrote:

> Has anyone fooled with using NTP on a beaglebone black running Debian (the
> beagleboard.org image)?
>
>
> I assume it's just a matter of turning on ntpd (which I'm not sure is even
> installed) and/or running ntpdate (I'm not looking for super accuracy..
> it's for a sprinkler timer)
>
>
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Re: [time-nuts] PPS phase between two GPS units.

[Graham / KE9H]

Are they running off the same power supply?
If so, I would run them from different power supplies as an experiment.
--- Graham

==

On Tue, Dec 22, 2015 at 6:19 AM, Attila Kinali  wrote:

> On Tue, 22 Dec 2015 11:57:55 +0100
> Mike Cook  wrote:
>
> > > A sampling difference of 1 cycle with 48Mhz clocks would give you ~21ns
> > offset if not using sawtooth correction. Can you do the sawtooth
> correction
> > and see if the offset is reduced?
>
> This is the most likely explanation. The LEA-6 modules use a 24MHz
> oscillator
> which is doubled for the processor, leading to the 48MHz clock.
>
> >   Good thinking Brian. But I would expect the difference to wander from
> 21s
> > UNLESS the the two receivers clocks are lock stepping. Injection locking
> > might do this if the two module are physically close enough.
>
> Injection locking wont work by simply playing the modules close to
> eachother.
> The oscillators are shielded well enough that quite some injection energy
> would
> be needed. Unless the TIMEPULSE2 output of one module is used to generate a
> 8MHz signal which is directly injected into the power suplly of the other,
> i
> don't see how injection locking would work. And even then, I wouldn't be
> sure
> if injection locking could be acheived.
>
> What could be done, though, is to lift the shield over the cpu side of the
> LEA-6, unsolder the oscillator and use an external 24MHz oscillator to
> supply both LEA-6 modules.
>
> If you do this, you could even go as far as to use the sawtooth correction
> message to stear the reference oscillator. That way you wouldn't need to
> measure the PPS output and could to a "fully" digital control system
> instead.
>
> Attila Kinali
>
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Need tiny 5MHz 10x amplifier

[Graham / KE9H]

I would consider using a LVDS line receiver.

http://www.digikey.com/catalog/en/partgroup/lvds-differential-line-receivers/11820

They are available in SOT-23 package, and can have built-in hysteresis, and
3.3V
CMOS output.

--- Graham

==


On Sat, Nov 28, 2015 at 6:35 PM, Poul-Henning Kamp 
wrote:

> I need to convert a 5MHz 0.2Vpp AC coupled sine signal to a 3.3V
> CMOS compatible logic signal.
>
> The "default" comparator based circuit either requires a negative
> supply or 4 resitors for biasing the input and setting the zero level.
> (The hysteresis resistor is the same in both cases).
>
> Since space is a bit tight, I've been trying to find something like
> a "x10 self-biasing amplifier" but without luck.
>
> Any good ideas ?
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] NAVSTAR proteus GPS time and frequency unit

[Graham / KE9H]

GPS Time ignores (does not deal with) "Leap Seconds."
It is dealt with in the software translation from GPS time to UTC or local
time.
That is part of the reason there is a 16 second time difference between GPS
Time and UTC/local time.

--- Graham

==

On Mon, Nov 9, 2015 at 4:15 PM, Chuck Harris  wrote:

> Seems to me that there is more to this than just
> getting the displayed date wrong.
>
> It is true that the date will present wrongly, but
> what about leap seconds?
>
> If the GPS week rolls over at 1024, how will the
> GPS figure out which is the proper calendar date
> to apply the leap second?
>
> -Chuck Harris
>
> Hal Murray wrote:
>
>>
>> paulsw...@gmail.com said:
>>
>>> Hmmm then why do I have to figure it out at all? I don't care what the
>>> date
>>> says.
>>>
>>
>> Only that the Austron locks and does its frequency offset compare. It
>>> would
>>> be great not to have to do this.
>>>
>>
>> If you don't care about the date, then don't worry about it.
>>
>> It will do everything it did before.  The only glitch is that the date
>> will
>> be off by 1024 weeks.
>>
>>
>> If you can't get the right date into your GPS unit, you can work around
>> the
>> issue in software.  Just add 1024 weeks to the date until the date is past
>> the build time of your fixup software.
>>
>> That assumes you have some software to work with.  That won't help if you
>> are
>> using a program that the vendor no longer supports.
>>
>>
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Re: [time-nuts] Bad date out of HP Z3805A

[Graham / KE9H]

Yes, you are missing 1024 weeks.

Google: GPS week rollover.

--- Graham

==

On Sun, Nov 1, 2015 at 7:19 PM, Charlie  wrote:

> I have used a  HP Z3805A for my shack for a number of years. I recently
> wished to get the date output.  Hooked up my laptop, and found that while I
> had a stable, in spec 10 Mhz output, I now have a date of 3/17/1996.
>
> I did a system reset, and a new survey. The date on startup is 1/1/1996; It
> jumps to 3/17/1996 and stays there (over a week now). All other functions
> appear to be normal. Power off/on, no difference.
>
> Am I missing something?
>
> Thanks,
>
> Charlie
>
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Re: [time-nuts] Beginners GPS locked frequency counter question

[Graham / KE9H]

Chris:

If by "purely mathematical" you mean with infinite precision and infinite
accuracy in the calculations, then the answer is "No."

The counter is using integer mathematics, in a world with propagation
delays and clock jitter, and uncontrolled phase relationships.
So resulting rounding errors and lost remainders in division processes.
If you read the specs on any counter, you will find that there is a
absolute accuracy PLUS an error window of (typically) plus or minus one
count.  Both error sources are very real.

I assume you mean 136 kHz.

But the answer to your sound card question is that you can't just GPS lock
the data converter on the sound card.  If it is running in a different
"clock domain" than the synchronous signal processing that follows it, then
you usually start having buffer underflows and buffer overflows which
introduce signal integrity problems.  The sound card sampling clock is
usually derived from some master clock in the computer, such that the sound
card is running in the same clock domain as the rest of the computer, so
you more likely need to GPS lock the whole computer.  This capability is
normally not provided for consumer grade computers, so you will be on your
own for the circuit modifications.

If you are doing signal processing in a desktop or laptop computer, they
are not "real time" operating systems, so understand the implications of
that, too.

--- Graham

==



On Sat, Oct 31, 2015 at 5:50 AM, Chris Wilson  wrote:

>
>
>   31/10/2015 10:46
>
>I have a Racal counter locked to 1 MHz on its rear panel external
>input socket from my Trimble Thunderbolt GPS. I derive the 1 Mhz
>from a David Partridge divider board. If I also feed the counter
>with the 10 Mhz direct output from the same GPS it reads one or two
>Hz out. As I assume the counter is working purely mathematically
>why would that be please?
>
>
>As an aside, I work low frequency RF transmissions on 136 Mhz, and
>very narrow bandwidth. Can a soundcard be locked to GPS instead of
>its own internal crystal for precise frequency output?
>
>Thanks.
>
> --
>Best Regards,
>Chris Wilson.
> mailto: ch...@chriswilson.tv
>
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Re: [time-nuts] Celestial Navigation instruction being reinstated in the US Navy

[Graham / KE9H]

Both the sextant and the slide rule will still function after an EMP event.
Not much other electronic stuff will.
--- Graham / KE9H

==

On Mon, Oct 26, 2015 at 4:20 PM, paul swed <paulsw...@gmail.com> wrote:

> Crazy bit of humor/timing in all of this I guess.
>
> Oddly at the last MIT flea I picked up a very nice astro-compass including
> case and manual. Also a news clipping that the Navy was restarting training
> on celestial navigation. Now I just need to add a mount to the car dash
> board.
> All prepared for the day the Glenda GPS fails.
>
> By the way if its celestial navigation, next will be slide rules. Pretty
> hard to tamper with them. The only virus they get are cold.
> Regards
> Paul
> WB8TSL
> Sorry really going astray here.
>
> On Mon, Oct 26, 2015 at 12:52 PM, Scott McGrath <scmcgr...@gmail.com>
> wrote:
>
> > Or with the appropriate filters you can shoot the sun with a sextant like
> > the old time Mariners did
> > I still have a sextant and still use it along with a copy of Bowditch
> >
> > Content by Scott
> > Typos by Siri
> >
> > > On Oct 26, 2015, at 9:13 AM, Jim Lux <jim...@earthlink.net> wrote:
> > >
> > >> On 10/25/15 9:37 AM, jim s wrote:
> > >>
> > >> Somewhat time related.  The Navy realizes that GPS might not always
> > >> work.  I don't imagine that aircraft in the US Air Force will be able
> to
> > >> do this very reliably, and the article doesn't mention that service.
> I'm
> > >> guessing that a lot of strategic Air Force aircraft have star trackers
> > >> that will work some of the time w/o GPS (at night).
> > >
> > > There's an excellent set of CD-ROMs with about 50 papers on celestial
> > nav and time keeping from the Institute of Navigation.
> > >
> > > https://www.ion.org/publications/upload/CelestialNavTOC.pdf
> > >
> > > Papers in there about all manner of star trackers and celestial nav,
> > from prehistory through the Renaissance era, to modern computerized
> > celestial nav boxes, etc.
> > >
> > > $50, as I recall.
> > >
> > > Celestial nav during the daytime isn't all that hard, if you have a
> > suitable telescope.  With a 28x telescope on a theodolite, you can see
> > Polaris, for instance.  The trick is in finding it first.
> > >
> > >
> > >
> > >>
> >
> http://www.latimes.com/nation/la-na-celestial-navigation-20151025-story.html
> > >>
> > >>
> > >> Thanks
> > >> Jim
> > >> ___
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Re: [time-nuts] UBLOX LEA-5T Programming?

[Graham / KE9H]

There is a lot of jitter on a GPS 1 PPS output.
You need a big "flywheel" to smooth out the jitter errors.
GPS modules only have room for small flywheels.
--- Graham


On Fri, Oct 9, 2015 at 9:16 AM, Clint Jay  wrote:

> I am still learning and want to understand, if the PPS is good then why is
> the programmable output bad, as I understand it thus far, the PPS is
> derived from the same clock source or have I got that badly wrong?
>
> On 9 October 2015 at 12:16, Bob Camp  wrote:
>
> > Hi
> >
> > Doing a GPSDO by locking to the awful 10 MHz output from any of these GPS
> > modules
> > is not going to work very well. Given the very long time constants
> > involved in a GPSDO
> > control loop, doing it without code is going to be pretty difficult.
> >
> > A much easier approach:
> >
> > Grab the GPS PPS and a scope. Use it to set the Lucent boxes on
> frequency.
> > Repeat the process
> > once a week.  The direct lock will flop around by (likely many) ppb. Your
> > manual set will probably keep it
> > under 1 ppb for a week.
> >
> > Bob
> >
> > > On Oct 9, 2015, at 1:39 AM, Perry Sandeen via time-nuts <
> > time-nuts@febo.com> wrote:
> > >
> > > Hi,
> > > I have six of the older style (anodized solid aluminum case) Lucent
> > crystal oscillators that I’d like to turn into simple 10 MHZ output
> > GPSDO’s. I have some salvaged HP cases so I can have a linear PS and all
> > other stuff in one package.
> > > I’ve found two different choices of GPS relatively low cost units on
> > Ebay.
> > > One is a LUCENT M12+ GPS Timing Receiver W/100 Hz output  for  $19.99
> > Item 171886538138.
> > > The other is a UBLOX LEA-5T GPS module dev board 1PPS /USB/RS232/ntp
> ser
> > with two 1 PPS outputs for $49.90. Item 251785217093.
> > > IIRC, one output of a Ublox can be set to a 10 MHz.
> > > Can this model be set to have a 10 MHz output and is it easily done
> from
> > a PC? I have no coding ability.
> > > For more money I’d get a simpler phase detector circuit, which is all
> > I’m looking for. For less money I’d have to build more circuitry.
> > > A factor I don’t know is if the ublox is that much better/newer to
> > justify the price difference.
> > > I already have packed away two Oncore units with either a 1 KHz or 10
> > KHz output.
> > > Suggestions welcomed.
> > >  Regards,
> > > Perrier
> > > ___
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> >
>
>
>
> --
> Clint.
>
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
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Re: [time-nuts] I've designed a GPSDO, but how good is it?

[Graham / KE9H]

Nick:

From your description, it sounds like you have a frequency locked loop with
a maximum frequency sensitivity of 1 ppb, as opposed to a phase locked loop.

At the end of the 100 second count period, do you start over with a counter
set to zero, or do you carry forward any error from the previous period?

--- Graham

==




On Sun, Aug 16, 2015 at 2:31 PM, Tom Van Baak t...@leapsecond.com wrote:

 Hi Nick,

 Nice project. Thanks for sharing.

 I was hoping someone would someday use a cheap Sparkfun / Parallax /
 Adafruit GPS to make a low-cost GPSDO. Mostly what people on this list do
 is go to the extreme of using serious GPS timing receivers (such as Oncore
 M12+T, or ublox-5T or 6T or 8T) but those require significant amounts of
 configuration, tuning, survey, etc. to meet ultimate performance levels.

 The good thing about using a cheap hobbyist-grade 3D GPS/1PPS receiver is
 that they work anywhere, without fiddling or survey, within seconds of
 power-on. Ok, you lose a few ns of precision compared to serious receivers
 -- but for a TCXO that doesn't matter.

 Anyway, to answer your question -- to measure its true performance you
 only need two things. 1) a phase meter (or time interval counter) that's
 good to 1 ns or better, and 2) a local reference standard that's maybe 10x
 better than the TCXO and the Adafruit GPS. Usually that means a cesium
 standard, or supremely qualified GPSDO, or equivalent.

 A number of us here on the time-nuts list have such equipment at home. And
 unlike professional labs, we will do it for free/fun if you loan the GPSDO
 for a week.

 If you want to play with raw timing data from an Adafruit GPS board see
 file gps-mtk3339.txt.gz under http://www.leapsecond.com/pages/gpsdo-sim/
 and then use TimeLab for phase, frequency, and Allan deviation analysis (
 http://www.ke5fx.com/timelab/readme.htm).

 /tvb

 - Original Message -
 From: Nick Sayer via time-nuts time-nuts@febo.com
 To: time-nuts@febo.com
 Sent: Sunday, August 16, 2015 11:47 AM
 Subject: [time-nuts] I've designed a GPSDO, but how good is it?


 I’ve designed and make and sell a GPSDO on Tindie (
 https://hackaday.io/project/6872-gps-disciplined-tcxo). It’s brand new -
 I’ve sold a handful of them so far. So as to make this post not *entirely*
 self-serving, what I would like is some further guidance on how I can
 better characterize its performance.

 The GPS reference is a 1 pps signal (It’s the Adafruit Ultimate GPS module
 - a PA6H). The manufacturer claims an accuracy of ±10 ns, but that's
 accuracy relative to the true start of the GPS second. They don’t make any
 claim for stability.

 The oscillator itself (Connor Winfield DOT050V 10 MHz) has a short-term
 (though they don’t say how short that term is) stability of 1 ppb. The
 absolute accuracy of it is (I assume) irrelevant, because it’s a VCTCXO and
 the control voltage is steered by GPS feedback.

 The feedback loop takes samples over a 100 second period. That gives me an
 error sample with a granularity of 1 ppb. I keep a rolling sample window of
 10 samples to get an error count over 1000 seconds. I've kept track of both
 of these values for extended periods (days) as well as logging the DAC
 value (the number that's proportional to the control voltage). The 1000
 second sample window error averages zero, and it almost never exceeds ±7
 (every once in a while if I physically move it, it will show a momentary
 error glitch, but that shows up in the short term feedback sampling too).
 The 100 second samples are almost all 0 or ±1, with an occasional ±2
 showing up. As I said before, if I bonk the oscillator, it may briefly show
 a ±6 or so for one sample.

 If I pit two of them against each other on a scope and take a time lapse
 video (http://www.youtube.com/watch?v=9HkeCI90i44), you can see that they
 stay mostly locked with occasional periods of drift. I sort of assume that
 that represents periods where the two GPS receivers disagree as they decide
 differently how to select among the available satellites.

 I've been saying out loud that the oscillator is ±1 ppb from GPS over the
 1000 second window. I know of Allan variance, but I don't have anything
 else handy I can use for comparison. I also can't really afford to send one
 off for testing to a proper lab. In looking at
 http://tf.nist.gov/general/pdf/2297.pdf, it suggests that my results are
 relatively poor compared to what a GPSDO can achieve (more like 10^-12
 rather than 10^-9), but I assume that they’re able to use a higher
 frequency GPS reference than just 1 PPS (and they’re a lot pricier).

 What else can I do to try and characterize the performance? If mine is
 performing far more poorly than the same price ($175) can buy elsewhere,
 then what am I doing wrong?

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Re: [time-nuts] wtd: WWVB info

[Graham / KE9H]

As long as there is no analog audio bandwidth Nyquist filter, or it is
digital and scales with the sampling frequency, then I agree.
--- Graham

==


On Thu, Aug 6, 2015 at 5:24 AM, David G. McGaw david.g.mc...@dartmouth.edu
wrote:

 That is not true.  If the converter is set to 192kHz sampling, the
 bandwidth will be nearly 96kHz, typically at least 80kHz, not limited to
 20kHz.  That is the POINT of 192kHz sampling.

 David N1HAC



 On 8/5/15 10:03 PM, Graham / KE9H wrote:

 Scott:

 You won't be able to use an off-the-shelf audio card, because they will
 have
 filters that cut off just above human hearing limits, somewhere in the
 mid 20 kHz range.  I was referring to the data converter chips they use
 on those high end cards.  The circuit for ~80 kHz (Nyquist) low pass
 filters
 and antenna interface would likely be a custom card.

 For the guys talking about the Tayloe receivers, the Tayloe front end is
 just
 a down converter to get the HF or VHF signals down into the range that
 WWVB
 is already in.  So to receive WWVB, you only need the backend of the
 Tayloe
 receiver, ie., no Tayloe mixer required.  Just the (audio) data converter
 and the
 DSP.

 --- Graham / KE9H

 ==

 On Wed, Aug 5, 2015 at 5:47 PM, Scott Newell newell+timen...@n5tnl.com
 wrote:

 At 12:40 PM 8/5/2015, Graham / KE9H wrote:

 Content-Transfer-Encoding: 8bit

 There are several high end audio Analog to Digital Data converters that
 will clock at 192 kHz, ~23 bits ENOB, which puts a 60 kHz signal sweetly
 in
 the first Nyquist zone. Typical NF of the front end of the data
 converter

 Any specific recommendations? I've seen the Asus Xonar U7 (USB) and Asus
 Xonar D1 (PCI) mentioned on some of the SDR sites. (I'm running XP and
 linux.)


 --
 newell


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Re: [time-nuts] wtd: WWVB info

[Graham / KE9H]

There are several high end audio Analog to Digital Data converters that
will clock at 192 kHz, ~23 bits ENOB, which puts a 60 kHz signal sweetly in
the first Nyquist zone. Typical NF of the front end of the data converter
is 20 to 25 dB, so noise floor well below the atmospheric noise level at 60
kHz.  You would only need a preamp if you were running some negative gain
antenna.  Lots of dynamic range.  Won't overload until 2 Volts peak-to-peak
or so.  A very simple, high performance digital receiver front-end.

--- Graham / KE9H

==

On Wed, Aug 5, 2015 at 6:15 AM, Bob Camp kb...@n1k.org wrote:

 Hi

 The front end would be “dealers choice”. He who does the
 project gets to decide what gets used.

 If you look over some other designs, you can indeed get
 a device going with a 12 bit converter. The qualifier is that
 the signal to noise needs to be pretty good. With fades
 and switcher interference, you probably would notice its
 limitations.

 The “other end” of the design spectrum would be with a part
 designed as a high range font end chip. You can get to a lot
 of bits at low frequency. Even the prices aren’t all that crazy.

 Is there one and only one approach here? Not in any way. There
 are several thousand possible ways to do it. AGC or no AGC would
 be a pretty major decision. Next decision would be things like clocks.
 15 MHz from a ($25) KS box that also puts out 10 MHz looks like a
 pretty good choice at the moment.

 Past that it’s decimators / filters and the usual DSP stuff (or any of
 a dozen alternatives). Given the high noise environment I’d lean towards
 a DSP approach.

 Most of the choices run into the easy / quick / cheap tradeoff triangle.
 I’m
 sure that the debating process can find a solution that should “cost 10
 cents”. I’m
 also sure that a basement lash up of available parts is quick, but hard to
 reproduce.
 I’m not terribly surprised at the lack of 10 cent solutions. I’m a bit
 surprised
 that there are no unique lash up designs. The debate process seems to
 have made this a pretty un-attractive thing to do.

 Bob

  On Aug 4, 2015, at 11:36 PM, Hal Murray hmur...@megapathdsl.net wrote:
 
 
  kb...@n1k.org said:
  So far there have not been any home brew design radios show up that will
  demodulate and lock to the new data format. There is plenty of info on
 the
  transmit format. The demodulation approach is not crazy hard. That said,
  there’s still a lot of work to get a receiver running.
 
  Has anybody looked into a software approach?  What sort of front end
 would
  you want?
 
 
  --
  These are my opinions.  I hate spam.
 
 
 
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Re: [time-nuts] wtd: WWVB info

[Graham / KE9H]

Scott:

You won't be able to use an off-the-shelf audio card, because they will have
filters that cut off just above human hearing limits, somewhere in the
mid 20 kHz range.  I was referring to the data converter chips they use
on those high end cards.  The circuit for ~80 kHz (Nyquist) low pass
filters
and antenna interface would likely be a custom card.

For the guys talking about the Tayloe receivers, the Tayloe front end is
just
a down converter to get the HF or VHF signals down into the range that WWVB
is already in.  So to receive WWVB, you only need the backend of the Tayloe
receiver, ie., no Tayloe mixer required.  Just the (audio) data converter
and the
DSP.

--- Graham / KE9H

==

On Wed, Aug 5, 2015 at 5:47 PM, Scott Newell newell+timen...@n5tnl.com
wrote:

 At 12:40 PM 8/5/2015, Graham / KE9H wrote:

 Content-Transfer-Encoding: 8bit

 There are several high end audio Analog to Digital Data converters that
 will clock at 192 kHz, ~23 bits ENOB, which puts a 60 kHz signal sweetly
 in
 the first Nyquist zone. Typical NF of the front end of the data converter


 Any specific recommendations? I've seen the Asus Xonar U7 (USB) and Asus
 Xonar D1 (PCI) mentioned on some of the SDR sites. (I'm running XP and
 linux.)


 --
 newell


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Re: [time-nuts] 10MHz Square to Sine Wave Conversion

[Graham / KE9H]

All you need is a 10 MHz low pass filter.

How far down do you need the harmonics/spurious to be?

If 40 dB suppression of the 2nd and 3rd harmonics is adequate,
(you can't see the distortion with the eye on an oscilloscope)
you can make your own for about $2 in parts, not including a PC board or
housing.

Feel free to copy the low pass filter (L1, C9, C10) from here:
http://openhpsdr.org/wiki/index.php?title=EXCALIBUR

Or for about $35, you could get the same performance from an inline BNC
filter from Minicircuits.

http://www.minicircuits.com/pdfs/BLP-10.7+.pdf

If you need more harmonic suppression, buy two and put them in series.

--- Graham

==



--- Graham

==



On Thu, Jul 16, 2015 at 12:49 PM, skipp Isaham via time-nuts 
time-nuts@febo.com wrote:

 re: 10MHz Square to Sine Wave Conversion

 The GPSDO I recently acquired outputs a 10 MHz square wave. I'd like
 to convert it to a sine wave and I am looking for suggestions and info re
 any reasonable pre-made circuits and/or boards. No sense reinventing the
 wheel if I can avoid it.

 Otherwise I will start from scratch and make a new wheel

 Thank you in advance for your replies.

 Regards,

 skipp

 skipp025 at yahoo dot com

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Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought

[Graham / KE9H]

Be aware that there are about 100 variations on IRIG B, that is, B000
through B257.
You should obtain a copy of IRIG STANDARD 200-04, the 2004 version,
which I believe is the most current.  It is available on line, if you
Google for it.

--- Graham / KE9H

==

On Tue, May 19, 2015 at 8:11 PM, Neil Schroeder gign...@gmail.com wrote:

 A bc635 can be had on eBay for almost nothing. It's not a pleasant piece of
 gear, but this is one task it can help you with greatly.

 Tools exist to let you analyse the stream extensively, and the Api is
 trivial to learn -but not super featured at the high level.

 On Tuesday, May 19, 2015, Tim Shoppa tsho...@gmail.com wrote:

  See for example the Truetime 820 decoder. Discriminators, One-shots, and
  Flip-Flops with pots to tweak the levels.
 
  Tim N3QE
 
  On Tuesday, May 19, 2015, Joseph Gwinn joegw...@comcast.net
  javascript:; wrote:
 
   I'm studying up on how IRIG-B decoder circuits work.  What are the good
   approaches, the bad approaches, especially in the presence of noise?
   (I asked on the NTP group, with little result beyond the C/C++ decoder
   software written for the audio channel of a 1990s Sun workstation,
   which it ate alive: 50% cpu load.)
  
   Are there decoder ICs available?
  
   The closest to a decoder IC I've found is some FPGA code from a partner
   of Microsemi (nee Symmetricom):
  
   ..
  
 
 http://www.microsemi.com/products/fpga-soc/design-resources/partners/semquest
   
  
   All marketing and little technical information.  I'll have to find out
   the details.
  
  
   I find very little, though I did find one intriguing idea using a
   Costas Loop to lock to the 1 KHz carrier, and a posting suggesting
   squaring the input signal and phase-locking to the 2 KHz result.  Most
   recent articles on IRIG decoders come from Chinese sources, mostly in
   the AC power industry.
  
   Joe Gwinn
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Re: [time-nuts] Mini-time lab cost and maintenance

[Graham / KE9H]

Adam:

It depends.

What are you trying to do?
How much accuracy is needed?
Do you mean just time, or some other metrics, too?

--- Graham

==

On Mon, Apr 6, 2015 at 11:30 AM, Adam Blakney akblak...@gmail.com wrote:

 I was wondering how expensive it would be to have even a small and lower
 level time lab. What are some less expensive models of machinery i would
 need, and how much maintenance is required?

 Thanks, Adam
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Re: [time-nuts] Comparing the BeagleBone Black Raspberry Pi asNTP servers

[Graham / KE9H]

David:

If you are running headless, that is, not using the on board
video-graphics system,
all interaction with the unit is via the console, local or SSH.

In this case, I would use the console version as described above.  It is
about
one tenth the size of the version you are using.

You will need to install ntp, and disable whatever time system is already
present.
As well as any time and logging services that you do not use, that you can
find.

Debian is in transition from using a services management system called
init to
a new system called systemd or system daemon.  Debian 7.8 you are using
is a mixture of both.  By Debian 8 (jessie) the transition will be complete
and
is an almost pure systemd environment that will give you a centralized
location
and command set to view and turn on/off all services, including the
recurring
time-based ones.

Jessie is in test currently, and should be released in the next few months.
It is the OS for the new Beaglebone X-15 due out mid-year.  They have not
yet released a console version, but it real close.

The other thing that will help is getting rid of the cape-manager system you
are using, that is file i/o based.  There is a lot of file scanning going
on that
is not useful in time critical applications.

--- Graham

==



On Sun, Mar 22, 2015 at 8:29 AM, Mike George mgeo...@tuffmail.us wrote:

 David:

 On this page:

 http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#BBW.
 2FBBB_.28All_Revs.29

 they list an alternative console only image:

 https://rcn-ee.com/rootfs/bb.org/release/2015-03-01/
 console/bone-debian-7.8-console-armhf-2015-03-01-2gb.img.xz

 It might be easier starting with that if you don't intend to use graphics.

 Mike

 On 3/22/2015 03:46, David J Taylor wrote:

 David:
 On the BBB, were you running the fully loaded release, or the minimum
 console version of the OS?
 Which specific version of the OS?

 Thanks,
 --- Graham
 =

 Graham,

 The download was:

  bone-debian-7.8-lxde-4gb-armhf-2015-03-01-4gb.img.xz (547,024,548 bytes)

 which was from the Recommended Debian Images from:
 http://beagleboard.org/latest-images.  Perhaps there are some services
 or background tasks I can disable to reduce the CPU steady load from its
 present 16% average level?

 73,
 David GM8ARV


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Re: [time-nuts] Comparing the BeagleBone Black Raspberry Pi as NTP servers

[Graham / KE9H]

David:
On the BBB, were you running the fully loaded release, or the minimum
console version of the OS?
Which specific version of the OS?

Thanks,
--- Graham

==


On Sat, Mar 21, 2015 at 11:23 AM, David J Taylor 
david-tay...@blueyonder.co.uk wrote:

 Folks,

 I've just put up my first draft of a comparison of these two popular
 devices as NTP servers:

  http://www.satsignal.eu/ntp/BBB-vs-RPi.html

 Comments welcomed - I know it's an imperfect test!

 Cheers,
 David
 --
 SatSignal Software - Quality software written to your requirements
 Web: http://www.satsignal.eu
 Email: david-tay...@blueyonder.co.uk
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Re: [time-nuts] 50 ohm driver

[Graham / KE9H]

The question is not the frequency, but the edge rate.  For a 1 PPS signal,
how fast a rise time do you need?  Do you want to know the time of the
edge to 1/100 second? one microsecond? one nano-second? A few pico-seconds?

If you want to know the time of the edge to one nano-second, then you
need a driver that can push sine-waves at over a few GHz. Not 10 MHz.

--- Graham / KE9H

==

On Sat, Mar 7, 2015 at 7:58 AM, Didier Juges shali...@gmail.com wrote:

 Martyn, if you only need 1Hz, I recommend you use a MOSFET driver like the
 MIC4420 series or the UCC27531, powered from 10V with a 50 ohm output
 resistance. These parts have several A current capability, 18V or more max
 VCC and are designed to drive capacitive loads (large MOSFET gate
 capacitance). It would not work at 10MHz (because of propagation delay and
 self heating), but at lower frequencies, they work very well.
 The UCC27531 has lower propagation time and comes in an SOT-23 package, the
 others are available in DIP-8 and SO-8.

 Didier KO4BB

 On Thu, Mar 5, 2015 at 3:59 PM, Martyn Smith mar...@ptsyst.com wrote:

  Hello,
  Thanks for all the feedback.
  I should explain.  I have an existing product that uses the 74AC14.
  I have a customer who needs 5V into 50 ohm and can’t wait for the
  competitive product that does this, or for me to re-design my unit.
  So I have been looking for a quick fix.
  I got excited when I found the SN74AS1004AD which has the exact same
  function and pin out but delivers 48 mA per channel.
  While one output did give me 0-3.0 V into 50 ohm, combining them, as we
 do
  for the 74AC, actually produced worse results.
  Maybe the output driver is different.
  Anyway I’ve managed to get 0-4.8V by jacking up the supply voltage to 5.7
  V for the 74AC14 and making the three 47 ohm resistors 0 ohm.
  Risetime  4 ns.
  Basically to ideas that TimeNuts gave me.
  I’m just worried the IC may die after a few months.  But since the
  customer will only use it at 1 Hz and hopefully 50:50 duty, or less, I
 hope
  to get away with it.
  Of course if he removes the input and the outputs are on high, then that
  may be a problem.
  BTW, the reason he wants this high voltage is because he is driving a
 very
  long cable from the distribution  amp to the actual receiver.
  Anyway I have an IC on test for a week to make sure it lasts.
  Regards
  Martyn
 
 
  Today's Topics:
 
 1. Re: 50 ohm Driver (Bob Albert)
 2. Re: 50 ohm Driver (Graham / KE9H)
 3. Re: 50 ohm Driver (Tom Van Baak)
 4. Re: 50 ohm Driver (Hal Murray)
 5. Re: 50 ohm Driver (Dan Kemppainen)
 6. Re: Trimble Thunderbolt NMEA ? (Didier Juges)
 7. Re: 50 ohm Driver (Bob Camp)
 8. Re: 50 ohm Driver (Charles Steinmetz)
 9. Re: new tdc from Texas (Angus)
10. Re: new tdc from Texas (Attila Kinali)
 
 
  --
 
  Message: 1
  Date: Wed, 4 Mar 2015 16:49:11 + (UTC)
  From: Bob Albert bob91...@yahoo.com
  To: Discussion of precise time and frequency measurement
  time-nuts@febo.com
  Subject: Re: [time-nuts] 50 ohm Driver
  Message-ID:
  1276775018.2671439.1425487751520.javamail.ya...@mail.yahoo.com
  Content-Type: text/plain; charset=UTF-8
 
  5V into 50 Ohms means 100 mA.  Perhaps you need a medium power transistor
  amplifier or opamp.
  Bob
 
 
   On Wednesday, March 4, 2015 6:09 AM, Martyn Smith 
 mar...@ptsyst.com
  wrote:
 
 
  Hello,
 
  A quick question.
 
  My output driver for a simple amplifier.
 
  I use three gates (in parallel with resistors) from a 74AC14 to give me
  about 0-3.2V into 50 ohm.
 
  I want to have a driver that gives me a full 0-5V (at least 0-4.5V) swing
  into 50 ohms.
 
  Can anyone recommend an IC that can delivery this.
 
  But it needs to have similar jitter performance to the 74AC14.
 
  I use it up to 10 MHz.
 
  Best Regards
 
  Martyn
 
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  --
 
  Message: 2
  Date: Wed, 4 Mar 2015 12:16:02 -0600
  From: Graham / KE9H ke9h.gra...@gmail.com
  To: Discussion of precise time and frequency measurement
  time-nuts@febo.com
  Subject: Re: [time-nuts] 50 ohm Driver
  Message-ID:
  capyj-yxrlkw6y-poglqwjss+mehm6ifc+etyb-mcczkhjpw...@mail.gmail.com
  Content-Type: text/plain; charset=UTF-8
 
  Building on top of John's comments, if you are using a logic gate, look
 at
  the
  maximum output (pull up) current per pin, set the series resistor so that
  this
  current is not exceeded into a short, then also see if there is a maximum
  total
  current draw for all gates combined, or some power input pin, and do not
  exceed
  that.
 
  You can also look at switching the termination resistor from a simple 50
  Ohm
  resistor to ground, to a Thevenin load, which is 100 Ohms from +V

Re: [time-nuts] 50 ohm Driver

[Graham / KE9H]

Building on top of John's comments, if you are using a logic gate, look at
the
maximum output (pull up) current per pin, set the series resistor so that
this
current is not exceeded into a short, then also see if there is a maximum
total
current draw for all gates combined, or some power input pin, and do not
exceed
that.

You can also look at switching the termination resistor from a simple 50 Ohm
resistor to ground, to a Thevenin load, which is 100 Ohms from +V to the
load point,
and another 100 Ohm resistor from the load point to ground. This way you
still have a 50 Ohm termination, but only draw one half the DC current.
In the event of no input, the receiver voltage will go to half scale. Make
sure your system will not misbehave when this happens.

Alternate driver is to use a video line driver with sufficient bandwidth.

--- Graham / KE9H

==

On Wed, Mar 4, 2015 at 7:54 AM, John Ackermann N8UR j...@febo.com wrote:

 One comment on the parallel AC gate approach.  It may not be directly
 applicable to Martyn's issue, but there is a common confusion about the
 value of the summing resistors.

 Per Tom Clark, who came up with the idea, they are *not* intended to
 provide a near-end line termination to 50 ohms, but are simply there to
 protect the paralleled devices if the gates have slightly different delays
 (in which case one gate could end up sinking the other two).

 So, the commonly used 47 ohm value isn't magic.  You can use a lower
 value, and thus get more voltage at the far end.  I haven't experimented to
 see how far you can take that idea before destroying gates.

 John
 

 On 3/4/2015 5:26 AM, Martyn Smith wrote:

 Hello,

 A quick question.

 My output driver for a simple amplifier.

 I use three gates (in parallel with resistors) from a 74AC14 to give me
 about 0-3.2V into 50 ohm.

 I want to have a driver that gives me a full 0-5V (at least 0-4.5V) swing
 into 50 ohms.

 Can anyone recommend an IC that can delivery this.

 But it needs to have similar jitter performance to the 74AC14.

 I use it up to 10 MHz.

 Best Regards

 Martyn

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Re: [time-nuts] Motorola Oncore M12+T Sawtooth

[Graham / KE9H]

The source of the sawtooth is not the GPS receiver L.O., it is the
frequency of the master clock in the CPU.

The 1PPS line is a GPIO line from the CPU.
This means that the 1PPS line is constrained to only change state
on the edge of a CPU clock.  The CPU can calculate exactly when the
the 1PPS line is supposed to change, but if it is a 20 MHz CPU clock,
it can only change every 50 ns.  The sawtooth correction is the difference
between the constrained transition and the ideal transition.

--- Graham / KE9H

==

On Thu, Jan 29, 2015 at 4:27 PM, Tom Van Baak t...@leapsecond.com wrote:

 google for: m12 gps sawtooth

 The +/- 127 comes from the range of 8 bits.

 /tvb (i5s)

  On Jan 29, 2015, at 12:44 PM, Tom Wimmenhove tom.wimmenh...@gmail.com
 wrote:
 
  I've built a bunch of carrier board for the M12+T timing receiver. One
  thing I could not find much information about is the maximum sawtooth
  (which, I assume, related directly to the frequency of the receiver's
  internal LO). I know my particular module outputs a correction values
  between -15 and +15, in which case I could use a DS1023-25 delay-line
 chip
  which uses .25ns increments instead of the DS1023-100, which uses 1ns.
 This
  would give the overall circuit slightly better linearity. Problem is that
  the datasheet doesn't say anything about this, it just says -128..+127ns.
  Does anyone know if there are receiver units out there that have
 different
  LOs ?
 
  Regards,
  Tom
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Re: [time-nuts] Beaglebone NTP server

[Graham / KE9H]

Neil Schroeder wrote:

 Graham make sure you read up on dtb and fdt. Many if not most distros
don't
 have what you might call a default.

I have done several device tree overlays on the BBB, so I think I can
usually get the
I/O lines and pin-mux to do what I want them to do.  It was a total pain
figuring
it out without good documentation. Any distro that I use does contain the
cape manager, so I have a starting point.

==

David wrote:

 RPi cards have a way of proliferating - I have seven now!  At least two
are actually doing something useful.

When you get 24 of them, you can build a parallel super computing cluster.
:-)
http://www.amazon.com/gp/product/1783989440/

--- Graham

==

On Wed, Dec 10, 2014 at 10:56 AM, Paul tic-...@bodosom.net wrote:

 On Sun, Dec 7, 2014 at 3:10 PM, folkert folk...@vanheusden.com wrote:

  Regarding the fs error
 

 As an aside: this thread is like a zombie.  Folkert's reply was to my post
 from  March
 2014
 in response to Henry Hallam who was replying to a message from
 Gabs Ricalde posted in June 2013.

 I suppose I should have waited six months to post this.
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Re: [time-nuts] Beaglebone NTP server

[Graham / KE9H]

Dan:

When you forced/locked the CPU frequency at 1 GHz, did you by any chance
measure what it did to the CPU case/package temperature?  Or current drain?

I note that you used BBB pin P8.7 for PPS input.  That allowed you to use
it for either
pps-gpio or TIMER4 pps-gmtimer, by just changing the pin-mux?

--- Graham

==

On Wed, Dec 10, 2014 at 7:58 PM, Dan Drown dan-timen...@drown.org wrote:

 Quoting Paul tic-...@bodosom.net:

 Using a PRU seems like overkill if all you want from the BBB is NTP.  The
 standard pps-gpio should move the system clock precision below
 system/network jitter (.5 to 1 microsecond).  The next step is using a
 timer (TIMER4) which should get you into .1 microsecond offsets.


 As a note to people wanting to use the timer hardware on the BBB - I have
 a driver for it at https://github.com/ddrown/pps-gmtimer

 I wrote up the results in using it at http://blog.dan.drown.org/
 beaglebone-black-timer-capture-driver/

 The summary of it is:

 pps-gpio - 50% of the time local clock offset within +/- 0.07us, 98%
 within +/- 0.61us

 pps-gmtimer - 50% of the time local clock offset within +/- 0.04us, 98%
 within +/- 0.43us

 Also, if you're using pps-gpio, you might want to disable cpufreq and
 force your processor to 1GHz.  It'll help with interrupt latency and jitter.

 cpufreq ondemand, 300MHz-1GHz - http://dan.drown.org/bbb/run9/
 interrupt-latency.png
 98% of interrupts handled 12.92us-23.21us after the event happened.

 cpufreq forced 1GHz - http://dan.drown.org/bbb/run8/interrupt-latency.png
 98% of interrupts handled 6.04us-8.58us after the event happened.

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Re: [time-nuts] Beaglebone NTP server

[Graham / KE9H]

For those of you that have gotten the BeagleBone Black up and
running as an ntp server with the 1PPS signal input in kernel space,
what gpio input pin is being used?

I guess I am asking if the kernel pps-gpio has a specific preferred pin,
or whether it can be mapped to any available gpio pin.

Thanks,
--- Graham / KE9H

==

On Tue, Dec 9, 2014 at 11:18 AM, Bob Darlington rdarling...@gmail.com
wrote:

 Hourly cron jobs, perhaps?

 -Bob

 On Tue, Dec 9, 2014 at 8:04 AM, David J Taylor 
 david-tay...@blueyonder.co.uk wrote:

  Thanks for pointing this out David,
  Compiling an new kernel was holding me back. I followed your instructions
  and
  everything works beautiful. The PI that is running the PPS timekeeping
  with NTP
  is serving as a VLF receiver as well. Taxing the poor CPU, but with
  kernel PPS support
  the NTP daemon has become way happier! (see attachment)
 
  73, Frits W1FVB
  ==
 
  Oh, yes!  That's much better, Frits!  Delighted to have helped!
 
  (Although it now shows up an hourly periodicity - any idea what might be
  causing that?)
 
  73,
  David GM8ARV
 
  --
  SatSignal Software - Quality software written to your requirements
  Web: http://www.satsignal.eu
  Email: david-tay...@blueyonder.co.uk
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Re: [time-nuts] Beaglebone NTP server

[Graham / KE9H]

Dan: Thanks. I don't know where you were quoting from, but it was the
answer I needed.

Paul: I found BB-BONE-GPS-00A0.dts, so I will start editing/hacking from
there.
I plan to run under Debian 7.7 or 8-Testing.

Thanks,
--- Graham

==

On Tue, Dec 9, 2014 at 5:33 PM, Paul tic-...@bodosom.net wrote:

 On Tue, Dec 9, 2014 at 12:59 PM, Graham / KE9H ke9h.gra...@gmail.com
 wrote:

  I guess I am asking if the kernel pps-gpio has a specific preferred
 pin,
  or whether it can be mapped to any available gpio pin.
 

 The provided-with-stock-dtb pin is: 0x40 which is P9 pin 15.
 I use the only free pin on P8 or P9: 0x7c which is P8 pin 26

 There are various maps/charts/lists around with the pins.  Just decompile
 /lib/firmware/BB-BONE-GPS-00A0.dtbo and fiddle if you want a different
 pin.  The Debian relases come with dtc, I don't know about Angstrom.

 e.g.
 http://www.embedded-things.com/bbb/beaglebone-black-pin-mux-spreadsheet/
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Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

[Graham / KE9H]

Bill:

On cable TV systems, 50 MHz to 500 (or higher) are the forward channel.
(Head-end to client.)
Below 30 MHz is the reverse channel, for data going from the client to the
cable company.
The band 30 to 50 is a cross over zone for the band splitting filters.


It is designed to not amplify the forward direction below 50 MHz.

--- Graham

==

On Fri, Oct 31, 2014 at 4:07 PM, Bill Riches bill.ric...@verizon.net
wrote:

 Hi Bob,

 I connected 10 MHZ test jack output to a 15 db el-cheepo CATV amp and the
 output of that to a 4 way splitter.  Splitter outputs went to 3336-3586 and
 counter.  All seem to like the ref signal.  Output of the amp takes makes
 the semi-square wave into a sick saw tooth.  Amp is only rated from 50 to
 500 mhz so strange things are happening with 10 MHZ input.  Other CATV amps
 do have better low fx response - will play with that later.

 I have 10 mhz pulse from Lucent into trigger input of 465 scope and
 Thunderbolt gps output into vertical input of scope.  Time base is set for
 .01 Usec per div. I notice that trace moves right to left then left to
 right about every 5 min or so.  Moves about 3 div before changing
 directions.  Why?  Is the Lucent still making a list?  It has only been on
 for a few hours.  It takes about 10 min for GPS to go out from a cold
 start. (My Thunderbolt and RB do not change direction when using one as
 trigger and the other for vert input to scope)

 I ordered a USB to RS422 converter cable - will be here next week.  What
 program is sort of working?  Using Windoze 7 64bit and have an old XP
 machine available.

 Sure do appreciate all the info from our time nuts gurus!

 73,

 Bill, WA2DVU
 Cape May, NJ


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Re: [time-nuts] Really fast ADC needed

[Graham / KE9H]

A startup in Massachusetts named Hypres has/had exactly what you want.
It is a cryogenic delta-sigma converter using some kind of quantum logic.
As I remember it did about four bits per sample at up to 40 Giga-samples
per second.
You have to run it submerged in liquid Helium.  But they would sell you the
liquid
helium generator system as part of the package.

http://www.hypres.com

But I can't get their web-server to come up, today.  So either some IT
problems,
or they are out of business.  If you Google them, they come up in the
search, so
either they are still around, or were recent enough for Google to remember.

I would like to see what you are going to use to absorb 120+ Gigabits per
second of
continuously streaming data.  It will take a server cluster, doing nothing
else, if you
can figure out how to parallelize the problem.

Good luck,
--- Graham

==


On Thu, Oct 30, 2014 at 10:55 AM, Sebastian Diaz sebas.d...@gmail.com
wrote:

 Fujitsu used to sell ultra-fast charge mode interleaved sampler (CHAIS)
 ICs.
 These have analog bandwidths of ~20GHz and sampling rates of 65 GS/s, 8-bit
 resolution, with ENOB 5-6.

 They pipe data out at  a max 128 bit* 500MHz (8 GB/s). How are you planning
 to digest this data stream?

 Regards,
 Sebastian







 On Thu, Oct 30, 2014 at 7:23 AM, Alexander Pummer alex...@ieee.org
 wrote:

  pipeline converter, but it needs as many clock period as the required
  bits, does he has the fast logic to deal with that amount of data?
  73
  KJ6UHN
  Alex
  On 10/29/2014 9:46 PM, Mark Sims wrote:
 
  A friend of mine is looking for an ADC that can do 5 bits at 20-40
  gigasamples/second...  there is a timing related component to the
 project.
  Any ideas of who makes a decent beastie?  It needs to supply continuous
  data so things like a fancy scope won't do...
 
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Re: [time-nuts] Is this measurement for real?

[Graham / KE9H]

Dave:

What is it that you almost don't believe ?

That it is this good?  Or that it is this bad?

Remember that the sound card has a sampling clock, that also contributes 
to any errors.


If it is a regular computer sound card, then it is using the same $0.33 
crystal reference as the

rest of the computer.

--- Graham / KE9H

==

On 12/7/2013 2:24 PM, quartz55 wrote:

I've been testing my soundcard measurement capability with Speclab, so I hooked 
my LPRO Rb to lock my Moto Service Monitor, fed the 1K audio out into the sound 
card and I measured the freq over about a half hour.  I got a spread of about 
107uHz.  I've tried a few other things through my TS2000 using a 1500Hz tone 
from the USB and I can see when the fan goes on and off although I have the RX 
main osc locked to the GPSDO with the XRef from VK3HZ.  I can only assume the 
drifting in the RX is due to the DSP processing crystal drifting with temp.  I 
get about 13mh drift on that.  Anyhow, here's a shot of the 1000Hz directly 
into the soundcard with Speclab. 
http://i251.photobucket.com/albums/gg287/DogTi/time/1k30m_zpsc4173981.jpg  I 
almost don't believe it, does anyone else?

Dave
N3DT
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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Graham / KE9H]

Stephan:

This sounds like some kind of antenna placement issue.

What is your Latitude?

Can you describe your antenna systems?

Best case: Antennas above all nearby reflecting objects/buildings/trees, 
clear

view of the sky for 360 degrees,

Worst case: Indoors, patch antenna on the window edge of a North facing 
window, so that
100 percent of all signals received are via reflections and multi-path, 
bouncing from

tall buildings in the area.

When there are signals received via reflection, and the receiver changes the
set of satellites it is using for the solution, you will see a time jump 
equal to

the apparent change in location of the receiver, for the different solution.

With heavy multi-path/reflections, antennas just a few cm apart will be 
looking

at different solutions, and will jump time/location at different times.

--- Graham / KE9H

==

On 11/19/2013 10:45 AM, Chris Albertson wrote:

Two antennas near each other?   Could they interact under some conditions?

Could you be seeing multi path in some satellite geometries?

  Try spacing them apart or BETTER get a splitter and use only one antenna
but take the second antenna an far away, I wonder if it is acting like a
reflector or if the amplifier is radiating EMI.


On Tue, Nov 19, 2013 at 6:01 AM, Azelio Boriani azelio.bori...@screen.itwrote:


One M12+ is the reference and the others are DUTs? Three times but in
one direction only for a 300ns total or what? The offset returned to
0? Please, detail better what happened.

On Tue, Nov 19, 2013 at 12:17 PM, Stephan Sandenbergh
ssandenbe...@gmail.com wrote:

Hi,

I've recently measured the 1PPS outputs of three Motorola M12+T GPS
receivers using two HP53131A TICs. Antennas are located next to one

another.

Now I notice the one M12+T has changed its time offset by 100ns three

times

over the period of 48hrs. The jitter remains the same, only the offset

that

changes.

I'm currently having a re-run of the measurement. But, in meanwhile, has
anyone seen this kind of behaviour? A firmware issue perhaps?

Regards,

Stephan.
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Re: [time-nuts] Off Topic Sortof: Board Rework Stations

[Graham / KE9H]

John:

We have one at work.  It basically works as represented.

It takes some skill to run, and takes some time to develop the
safe settings for soldering different sized items.  It puts out a tremendous
amount of infrared heat, and you can melt things if you are not careful.
For instance, it will melt plastic connectors close to the part being 
reworked.


You want to use it in a well ventilated area.  It heats the board to be 
reworked

from the underside to close to solder temperature, then uses infrared
from the top side to push the temperature for the part in question
above solder melting temp., and sometimes things close by.

The underside heater is covered with silicon rubber, and gives off strong
odor when hot.  Hot PCB boards give off strong odors, and of course, you
are melting solder and flux.  So, good ventilation is highly recommended.

You will need to practice on a few scrap boards before you try to solder
something valuable.  In the hands of a skilled operator, it does beautiful
work.

--- Graham

==

On 11/13/2013 9:00 PM, John C. Westmoreland, P.E. wrote:

Hello All,

I was wondering if anyone on this list has used the T862++ rework stations
on the PCB's you work on -

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dtoolsfield-keywords=t862%2B%2Brh=n%3A228013%2Ck%3At862%2B%2B

Are these as good as advertised?

Thanks In Advance,
John Westmoreland
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Re: [time-nuts] Surface Mount OCXO Questions

[Graham / KE9H]

John:

All SMT OCXO's will either have a recommended PCB footprint in the spec 
sheet

or will refer you to a recommended footprint in another document.

Some don't care about a ground plane under the part, some require it
with no crossing signals, some require an open thermal hole underneath
the oven.  I have seen all three cases.  As usual, it is suggested that you
read the [] manual.

Best regards,
--- Graham / KE9H

==


On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote:

Hello,

I was wondering if I could get some recommendations on surface mount OCXO's
vs. the traditional through hole.

I was also wondering on the board layout - if you found it necessary to
leave a thermal moat so to speak - and what worked best.  Maybe the OCXO
has an internal air barrier that maybe would make this unnecessary - not
sure.

Your input and experience appreciated.

Thanks,
John Westmoreland
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Re: [time-nuts] Surface Mount OCXO Questions

[Graham / KE9H]

John:

Look at the ppm (or however they express it) as to the sensitivity of the
frequency stability of the OCXO relative to Voltage input.

Say the oven power drops from 3 watts to 1 Watt as the oven comes up
to temperature.  At 3 Volts, relative to 12 Volts, for a given resistance,
it is four time the Voltage change due to the higher currents, and an 
additional
four times the percentage of the operating Voltage as a ratio.  So 
additional

design consideration for Voltage control/stabilization is needed.

If you have a solid (wide, thick, multi-layer) ground, then that can
work.  To reduce the voltage drop feeding the OCXO, you might consider
putting a dedicated LDO regulator, right at the OCXO, that shares the ground
reference with the OCXO, so any voltage drop in the feed side is removed,
as well as any Voltage variability with current in the ground system.

As to why they are selling the 3.3V part, they probably started selling it
before they had some customers get into performance issues per the above.
But once offered, they have to continue to support their customers.

I think they are just telling you that it is somewhere between 4 and 16 
times

easier to get the full performance out of the part with a 12 Volt power feed
than a 3 Volt power feed, not that you can't get full performance with a 
3.3V feed.


I am sure their parts meet specs, you just need to understand them.

P.S. - I would stick with linear regulators feeding the OCXO, not a 
switcher.


--- Graham

==

On 10/30/2013 7:37 PM, John C. Westmoreland, P.E. wrote:

Graham and Time Nuts,

(thanks for the answers.)

I have another question - I am looking at a part from MTI.  I wanted to use
one of their 3.3V parts.  They are telling me to use the 12V part because
the 3.3V part can have an issue with ground loops due to the higher current
requirements at that voltage for the oven.

Have any of you experienced this?  Makes me wonder a little why they offer
the 3.3V part.  It would seem good layout can control any possibility of
ground loops becoming a problem.

Thanks and Regards,
John W./AJ6BC




On Wed, Oct 30, 2013 at 6:54 AM, Graham / KE9H time...@austin.rr.comwrote:


John:

All SMT OCXO's will either have a recommended PCB footprint in the spec
sheet
or will refer you to a recommended footprint in another document.

Some don't care about a ground plane under the part, some require it
with no crossing signals, some require an open thermal hole underneath
the oven.  I have seen all three cases.  As usual, it is suggested that you
read the [] manual.

Best regards,
--- Graham / KE9H

==



On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote:


Hello,

I was wondering if I could get some recommendations on surface mount
OCXO's
vs. the traditional through hole.

I was also wondering on the board layout - if you found it necessary to
leave a thermal moat so to speak - and what worked best.  Maybe the OCXO
has an internal air barrier that maybe would make this unnecessary - not
sure.

Your input and experience appreciated.

Thanks,
John Westmoreland


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Re: [time-nuts] Coax cable for volute antenna

[Graham / KE9H]

Go to eBay and search for semi rigid coax

If you know the RG designation for the specific size you are looking for,
search for that.

Mouser and Digikey don't carry.  And the people that do will have minimum
buys you are unlikely to be able to afford.

Look for listings by eBay id: de_w7eme
Or contact Jeremy directly (W7EME) and see if he can help you out.

--- Graham / KE9H

==


On 10/16/2013 11:30 PM, Jim Lux wrote:

On 10/16/13 8:26 PM, quartz55 wrote:
I've been searching for the small copper hardline I can use for the 
feed on the gps volute (egg beater) antenna.  Can anyone steer me 
where to get a foot or so of the small 50 ohm line so I can make a 
few antennas?  I've been searching mouser to no avail.




what size (0.141, 0.085, 0.047 OD)?


You probably won't find it at Mouser type places.  RF Coax, Pasternak, 
etc. are better bets. Uniform Tubes might send you a sample.



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Re: [time-nuts] HP E1938A Oscillator

[Graham / KE9H]

On 7/5/2013 12:23 AM, Perry Sandeen wrote:


List,
  
I was looking on Ebay for some HP E1938A

oscillators
  
What I found listed were:
  
HP E1938A 10 MHz Quartz Oscillator with EFC on PC

board. $100 Fluke.l
  
HP E1938-60201 Ovenized Crystal Oscillator  (on a PC board) $100 Tomy Chou
  
HP E1938A Ovenized Crystal Oscillator  W/O a PC board for $50 and free shipping from  2010bluebook.

My question is thus:  What does the PC board do?  All I need is a HP EFC 
oscillator that would
be better that my HP 10811-60111’s.
  
Do I need to worry that the E1938A’s without the

board maybe of lessor quality than the others?
  
Fluke.l says his units are good but not stellar.  The other venders say they have tested the

units and guarantee them to be good.  If
so, would it get better with aging?
  
So what does the collective wisdom/experience of

the group think?  TIA
  
Regards,
  
Perrier





The E1938A is a microprocessor controlled and managed oscillator. 
Probably with a lot

of control/correction/compensation data stored on the processor board.

Does anyone have any interface (I/O) definitions for the stainless steel 
oscillator module?


For the processor control board?

Instructions on how to calibrate  and compensate it?

My impression is that it is a lot easier for an experimenter to manage 
an HP10811 oscillator

where you just put power on it and a signal comes out.

Thanks,
--- Graham / KE9H

==


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Re: [time-nuts] Zendulum

[Graham / KE9H]

On 6/8/2013 1:40 PM, Don Latham wrote:

Neat! The path shape can be calculated to be isochronous, if I remember
aright...
Don



Hi:

Here's a kit I just built that's a pendulum that's a metal ball powered
by a small solar cell.
Haven't done any measurements yet, but the period is about a second.
http://www.prc68.com/I/GeekStuff.html#Zendulum

--
Have Fun,

Brooke Clarke



A real time-nut would lock it to his GPS 1PPS output.
--- Graham

==
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Re: [time-nuts] NTP Clock suggestions?

[Graham / KE9H]

Miguel:

If you are going to build your own, I would recommend you start with
something like the Microchip PIC32 Ethernet Starter Kit. Comes
with a free GCC C/C++ compiler and an Ethernet stack.

I happened to have one for another project, that already had a
four line serial LCD display hooked to it, as well as a serial port
command line interface running

Since I was already familiar with the Ethernet Stack that comes with
the Starter Kit, all it took was turning on the SNTP function in the
stack, and writing about ten lines of C code to get it running.

One update of NTP sourced UTC Hours-Minutes-Seconds time on the
display per command line request. (Anything more complicated is left as
an exercise for the student.)

That was after about an hour's research to find out the time
format that NTP uses (seconds since Jan 1, 1900) and the
(different) time format that UNIX uses (seconds since Jan 1, 1970).
And how they both deal with leap-seconds since their
epoch started.

Another hour of time figuring out how to convert that to
today's Hours, minutes, and seconds.  But that is easy,
once it (finally) sinks in how to work with an epoch.

Now, the real fun begins when you decide that you might
want to convert NTP or UNIX time to Day of Week, Month,
Calendar Year, Day of Year, Week of year, and
adjustments for local time zone, with daylight savings time.

That was worth about four hours research and going to bed with
a head-ache.  Learned all about Julian Day and Modified
Julian Day, which it turns out has nothing to do with
the Julian Calendar.  (Did you know that time started at high noon
on January 1, 4713 BC. ?)  Finally discovered a code snippet
in Tom Van Baak's C code repository that will do the
conversion.  (Thanks, Tom.)

A pox upon leap years, un-leap centuries, re-leap 4th centuries,
Roman Numerals, modulus 7 weeks that do not align with the year boundary,
months with no regular modulus structure, and no year 0.

Who sold us this?

Makes you appreciate the decimal time Star Date system used on Startrek.

--- Graham

==

On 5/27/2013 9:56 AM, Miguel Barbosa Gonçalves wrote:

Hi Bob!

On 27 May 2013 14:56, Bob Camp li...@rtty.us wrote:


Hi

Correct answer:

I don't think there is such a beast. Once you get away from the radio
controlled (WWVB etc) clocks the cost goes up quickly.


I don't understand why a microprocessor with an Ethernet controller and a 7
segment display would cost so much to manufacture... I think I'll build my
own.



Also correct, but a bit of a joke answer:

Raspberry PI driving your television set.  Alternatively make the Pi feed
control signals to a hacked normal clock.


Good joke :-) I imagine the electricity bill at the end of the month.

I would like to have a clock sync with my super precise stratum 1 servers
:-) what's the point in having them if I can see the time anywhere? :-)

Cheers,
Miguel
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Re: [time-nuts] NTP Clock suggestions?

[Graham / KE9H]

On 5/27/2013 2:40 PM, Kenton A. Hoover wrote:

A useful reference to own: 
http://www.amazon.com/gp/aw/d/0521702380/ref=mw_dp_sim_ss1?pi=SL500_SY125

--
Kenton A. Hoover
ken...@nemersonhoover.org
+14158305843



Kenton:

Thanks.
I ordered from Amazon.

--- Graham

==
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Re: [time-nuts] Follow-up question re: microcontroller families

[Graham / KE9H]

On 5/25/2013 3:40 PM, Bob Camp wrote:

  You can get a part with 1MB of flash, 128KB of ram, 6 UARTS, 4 16 bit A/D's, 
10/100 Ethernet, USB, and a bunch of other stuff for less than $10. Drop this 
and that, go to half the flash, and yup, the price is 1/2. Comes with a free 
toolchain and two very capable free versions of RTOS.



Bob:

I was wondering which manufacturer/part you were referring to.

Thanks,
--- Graham

==
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Re: [time-nuts] OT, looking for a good science forum

[Graham / KE9H]

On 1/26/2013 1:29 PM, Paul Amaranth wrote:

Message: 4
Date: Sat, 26 Jan 2013 16:28:19 +0100
From: Fabio Eboli fabi...@quipo.it
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] OT, looking for a good science forum
Message-ID: 5ef3f142b075fcab38182666a4e50...@quipo.it
Content-Type: text/plain; charset=UTF-8; format=flowed

Il 2013-01-26 14:58 Bob Camp ha scritto:

Hi

Platinum RTD's are a pretty good bet for -80C, they hold up well down
there. For calibration, ammonia and acetylene both have triple points
in the vicinity. I'd probably try ammonia first, but not for any good

Doesn't acetylene have a bad habit of dissociate when pure liquid?

Fabio.


Yes, it's normally stored disolved in acetone.  It also spontaneously 
dissociates
if pressures exceed 15 psig or 30 psi absolute.  That could put a real damper 
on your day.


Just pure acetone works well at dry ice temperatures.  We used crushed 
dry ice
in acetone as an alternative when the liquid nitrogen truck was late 
making its delivery

for the cryro lab.

--- Graham / KE9H

==
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Re: [time-nuts] Thermal noise contribution to phase noise

[Graham / KE9H]

Bruce:

The last time I looked, the thermal noise floor was still -174 dBm/Hz 
(at 300 Kelvin).


http://en.wikipedia.org/wiki/Thermal_noise

Are you saying Boltzmann's constant is off by 3 dB, or are we mixing 
apples and oranges here?


Is there a 3 dB adjustment between noise floor (at room temperature) and
the single side band phase noise measurement, which only looks at half
the noise, since it only looks on one side of the reference signal?

--- Graham / KE9H

==

On 1/15/2013 1:38 PM, Bruce Griffiths wrote:
I've noticed a disturbing tendency to quote the thermal noise 
contribution to phase noise as -174dBm/Hz instead of the corrent value 
of -177dBm/Hz as verified by measurement by NIST:

http://tf.nist.gov/phase/noisemeas.html

This error occurs in papers from Spectrum Microwave, Wenzel Associates 
and others.
Blindly propagating the results quoted in the early literature isnt 
particularly helpful given that the definition of SSB phase noise has 
changed in the intervening decades.


Bruce




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Re: [time-nuts] Cell timing error

[Graham / KE9H]

On 12/15/2012 9:38 PM, Hal Murray wrote:

GSM cell sites in the US have GPS because it is required to support E911
positioning.  I'm not sure if it is used for anything other than this, but
it doesn't have to be.

So it's cheaper to install and maintain GPS rather than make one measurement
and tell the setup where it is?




No.

In addition to knowing where the GSM cell site is, you time stamp the 
time of arrival of a
specific feature in the cellphone signalling system.  If the cellphone 
is heard by three
(or more) cell sites, then you can calculate the location of the 
cellphone within the

cell site using the time-of-arrival and speed-of-light calculations.

The CDMA systems inherently depend on knowing time to sub microseconds 
in order
to function.  You can extract similar information from the signalling 
systems in CDMA.


Newer cellphones have a GPS receiver front end inside the phone, which 
allows greater
accuracy than the time of arrival systems.  Many times, cellular signals 
bounce off
of things between the handset and the base station, introducing a path 
length change and
therefore a time-of-flight delay in the signal which causes errors in 
the time of arrival

calculations.

--- Graham / KE9H

==

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Re: [time-nuts] Cell timing error

[Graham / KE9H]

Greg:

You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.

--- Graham / KE9H

==

On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, ATT and tracfone (? carrier) are showing phone times 
very close to 1 min slow.  Virgin/sprint is ok.   I've never seen this 
before - usually it's a few s slow.


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Re: [time-nuts] getting a grip on 10811 drift (trying to read my instruments)

[Graham / KE9H]

Chris:

This says your EFC circuit is not working, and you are only
getting 0.05 Hz frequency change across the -5 to +5 EFC range.
The spec on the HP10811 is 1.0 Hz minimum.

And, yes, in a counter the  EFC circuit is not used, so no one would
know if it failed.

It is very simple circuit.  The only active component is a
varactor that the EFC voltage is applied to.

There was a very recent thread about someone else that
had to replace that varactor in a HP10811 and what he
used.

Search for thread titled HP 10811 Tuning Diode.
From the period October 18 through October 19, 2012.

--- Graham

==

On 11/15/2012 8:57 PM, Chris Howard wrote:

You all were right, my targeting of the 50 ohm resistor
across the oscillator output does not seem to have solved the
problem.   A good thing to do, probably, but not the answer.

While I was all excited about the resistor change I also
mapped out the control voltage (EFC) vs frequency change.
I wrote it out but didn't pay much attention.  Now
I've been pondering over that a bit.  My next theory
is that my EFC maybe isn't really doing very much.

First I need to know if I am reading this right.
My frequency counter is a Racal 1992  It reads
9.9997^6   as I write.  A total of 9 digits
with a smaller 6 to the right.

If I read this correctly, I'm looking at
9,999,999.97  Hz ?  If so, then I've got an EFC problem.

My EFC mapping looks like this (this was done before
I adjusted the coarse control)


-4.94 VDC 9,999,999.95
-3.70 9,999,999.95
-1.24 9.999.999.93
  0 VDC   9,999,999.93
+1.21 9,999,999.92
+2.44 9,999,999.92
+3.67 9,999,999.91
+4.90 VDC 9,999,999.90

It doesn't look to me like I am getting anything
like 1/2 hertz range using the EFC.  If that's
the case than my controller card is frantically
steering but not getting the desired result.

Or, if I'm reading it wrong,  maybe that last digit
is 0-5 meaning 1/2 a hertz and I am all wet (again).

This particular oscillator came out of an old HP counter
and I believe the EFC was wired to ground.  So maybe
the thing has never been exercised.  Are there versions
of the 10811 that don't have EFC guts inside?

Hope I'm not boring you all to death.

Chris
w0ep



On 11/9/2012 11:26 PM, WarrenS wrote:

Chris

HP 10811 can't drift that much that fast unless something is near broken, or 
being connected wrong like gnds or PS voltage.
Check the operation of the oven.

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Re: [time-nuts] getting a grip on 10811 drift (beginner-ish question)

[Graham / KE9H]

Chris:

I doubt that you have test equipment that can directly measure
the hourly aging frequency drift of the HP10811.

To get a handle on what you are dealing with, you need
to use the spec sheet on the HP10811 to calculate
the tuning sensitivity of the HP10811, in Hz per Volts.
(more likely scaled to something like micro-Hz per micro-Volt)
It is not linear, but this calculation will be close enough
to get you in the ballpark.

Then convert the count change you are seeing every
three hours to a microVolt change at the output
of your D-A converter and Op amp.

Convert that to Hertz using the above tuning sensitivity.

That will give you an estimate of what the drift rate
is.  Compare it to the spec on the HP10811 and see if
you are in the ball park.

Be aware that HP10811 oscillators that have been
turned off for a year or more, will typically take
about three weeks of continuous operation before they
rejoin their spec sheet drift specification.

--- Graham / KE9H

==


On 11/5/2012 8:49 AM, Chris Howard wrote:


I built a GPSDO using my own power supply,
a VE2ZAZ board, a Trimble Resolution T GPS
and a surplus  HP 10811 oscillator.


I'm having a bit of trouble with it.   I have it set up and
it locks ok and stays in lock so far.  But the recommended
long-term integration setting is not working for me.
I think it is about 3 hours.  At the end of every cycle
it does a control voltage adjustment, always in one direction.
If I understand it right, the oscillator is slowing and needs
an incremental bump downward of control voltage every time.

That seems like it is more than just long term drift.  But
I don't have my head around the quantities I'm looking at.

I can measure the control voltage change over time.  Can I convert that
into a frequency drift?  Or do I need to stop the voltage
adjustments and allow the drift to occur then do a measurement
of that directly somehow?

Is this type of behavior an indication of dire problems
with my 10811 oscillator?

Chris Howard
w0ep

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Re: [time-nuts] getting a grip on 10811 drift (beginner-ish question)

[Graham / KE9H]

Chris:

I doubt that you have test equipment that can directly measure
the hourly aging frequency drift of the HP10811.

To get a handle on what you are dealing with, you need
to use the spec sheet on the HP10811 to calculate
the tuning sensitivity of the HP10811, in Hz per Volts.
(more likely scaled to something like micro-Hz per micro-Volt)
It is not linear, but this calculation will be close enough
to get you in the ballpark.

Then convert the count change you are seeing every
three hours to a micro-Volt change at the output
of your D-A converter and Op amp.

Convert that to Hertz using the above tuning sensitivity.

That will give you an estimate of what the drift rate
is.  Compare it to the spec on the HP10811 and see if
you are in the ball park.

Be aware that HP10811 oscillators that have been
turned off for a year or more, will typically take
about three weeks of continuous operation before they
rejoin their spec sheet drift specification.
So, they will drift more for a little while, then settle
down to meet or exceed the spec sheet.

--- Graham / KE9H

==


On 11/5/2012 8:49 AM, Chris Howard wrote:


I built a GPSDO using my own power supply,
a VE2ZAZ board, a Trimble Resolution T GPS
and a surplus  HP 10811 oscillator.


I'm having a bit of trouble with it.   I have it set up and
it locks ok and stays in lock so far.  But the recommended
long-term integration setting is not working for me.
I think it is about 3 hours.  At the end of every cycle
it does a control voltage adjustment, always in one direction.
If I understand it right, the oscillator is slowing and needs
an incremental bump downward of control voltage every time.

That seems like it is more than just long term drift.  But
I don't have my head around the quantities I'm looking at.

I can measure the control voltage change over time.  Can I convert that
into a frequency drift?  Or do I need to stop the voltage
adjustments and allow the drift to occur then do a measurement
of that directly somehow?

Is this type of behavior an indication of dire problems
with my 10811 oscillator?

Chris Howard
w0ep

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Re: [time-nuts] multi time zone display for wall mounting?

[Graham / KE9H]

On 10/9/2012 6:04 PM, Mark Sims wrote:

Lady Heather supports a digital clock display.  You can zoom it to full screen. 
  It would not be difficult to add the two time zones to that display.  




You could use three of these:

http://www.sparkfun.com/tutorials/47

--- Graham

==

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