Re: [time-nuts] Casio Wave Ceptor wrist watch - quick accuracy test

[Jim Palfreyman]

I posted about my G-shock watch on this forum probably about 10 years ago.
Go look them up. I found mine superbly accurate and being in Tasmania I
cannot connect to any LF service. After a while it started to get a little
worse and I found you can take the back off and calibrate it.

My rechargeable battery has just started to fail and so I've ordered a new
one.

Jim


On Mon, 11 Jun 2018 at 18:20, Esa Heikkinen  wrote:

> Hi!
>
> There seems to be some kind of comeback going on with 80's style digital
>   watches. You may find replicas of some 80's models or even re-makes of
> the original models from original manufacturer.
>
> So I decided to get one. As a time-nut my primary goal was to have radio
> controlled 'atomic' model. So I ended up to Casio Wave Ceptor
> WV-59DE-1AVEF. There's many models available from basic digital models
> like this to very nice ones with with full titanium body (analog style).
> But because of the 80's is hot it had to be digital...
>
> Wave Ceptors suport all time signals formats (US, UK/German and Japan)
> and correct standard is automatically selected when home city is set.
>
> One of the first things to do was to test the accuracy with radio
> syncronization turned off. Correct time was fist set with DCF77. Then I
> switched off the synconization. After beign about three days off there
> was no significiant visible error on time. In the video we can see
> however about one frame error, which means about 40 milliseconds. Still
> that's pretty good result for wrist watch. Also, the syncronization will
> occur once per day when the reception is good.
>
> So the watch must be at least calibrated in the factory. Don't know if
> the watch performs any kind of self-calibration according to radio
> syncronization results, most likely not - but it would be technically
> possible.
>
> So far so good, it's accurate enough - at least as new. When
> syncronization is turned on, there should never be visible error on time.
>
> Here's my test video:
> https://www.youtube.com/watch?v=_A23buFeHd0
>
> --
> 73s!
> Esa
> OH4KJU
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Re: [time-nuts] time-nuts Digest, Vol 165, Issue 48

[AC0XU (Jim)]

Gary-

Interesting. The TICC is spec'ed to have a 10e-10 AD floor at 1 sec. Your 
measurement is slightly better than the spec. How can we know whether you are 
measuring the test source  (JL GPSTLXO) or the stability of the TICC itself?

Jim



At 03:10 AM 4/25/2018, you wrote:
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>Today's Topics:
>
>   1. Re: Cheap jitter measurements (Gary E. Miller)
>
>
>--
>
>Message: 1
>Date: Tue, 24 Apr 2018 20:45:08 -0700
>From: "Gary E. Miller" <g...@rellim.com>
>To: time-nuts <time-nuts@febo.com>
>Subject: Re: [time-nuts] Cheap jitter measurements
>Message-ID: <20180424204508.5794f...@spidey.rellim.com>
>Content-Type: text/plain; charset="utf-8"
>
>Time-nuts!
>
>I went ahead and bought the TAPR-TICC, it is a very impressive
>instrument.  For this setup it is combined with a Jackson Labs
>GPSTLXO as the 10MHz reference.  The JL is a GPS disciplined temperature
>compensated crystal oscillator.
>
>The first setup uses the TAPR-TICC in Period mode, outputting the PPS
>period individually for channel A and channel B.
>
>Channel A is the PPS of a plain u-blox NEO-M8N.  Channel B is the
>PPS of the JL GPSTLXO.
>
>Simple to get the cycle times from the USB serial port.
>
>Then I grabbed a copy of the easy to use Python Allantools.
>https://github.com/aewallin/allantools
>
>A little coding later and there are nice plots.  They were compared to
>the output of tvb's adev.c program.  Results are similar.
>
>Results are attached.  gps.png is the plain NEO-M8N.  GPSTLXO is the
>JL part.
>
>gps.png looks as expected.  GPSTLXO.png shows the quality of the JL part,
>but does have some odd divots in the plot.  Maybe artifacts of using the
>PPS derived from the reference 10MHz?  Or an artifact of the 10e6 divider?
>
>There are adev's of Rb standards here: http://www.ke5fx.com/rb.htm
>
>My guess is that the oadev at 1s would be about 50x better with
>a Rubidium?  But similar at 10k seconds?
>
>Comments?
>
>RGDS
>GARY
>---
>Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>g...@rellim.com  Tel:+1 541 382 8588
>
>Veritas liberabit vos. -- Quid est veritas?
>"If you can’t measure it, you can’t improve it." - Lord Kelvin
>-- next part --
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>
>--
>
>Subject: Digest Footer
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>**

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Re: [time-nuts] GPS coordinate differences between APRS.FI and Google Maps

[Jim Harman]

Perhaps aprs.fi is reporting in dd.mm (degrees.minutes) format vs decimal
degrees. That would be consistent with the numbers you are setting.

On Fri, Apr 20, 2018, 8:01 PM Azelio Boriani 
wrote:

> aprs.fi uses google maps... have you taken a look to your raw packets?
>
> On Sat, Apr 21, 2018 at 12:34 AM, Scott McGrath 
> wrote:
> > DATUM perhaps?
> >
> > Content by Scott
> > Typos by Siri
> >
> > On Apr 20, 2018, at 5:20 PM, Russ Ramirez 
> wrote:
> >
> > This has probably been mentioned before, but there is a significant
> > discrepancy between APRS.FI locations for DMR hotspots for example, and
> > what my Trimble receiver and Google Maps says when I use my address to
> > lookup the coordinates.
> >
> > On APRS.FI my location has to be 45.15 N, -93.39 W for the icon to be in
> > the right location on the map.
> >
> > On regular Google Maps, my QTH is correct and matches what my Trimble
> says
> > via Lady Heather within a few seconds. 45.2586 N, -93.6554 W.
> >
> > Do any of you know what causes this, and did I do anything wrong
> possibly?
> > TIA
> >
> > Russ
> > K0WFS
> > ___
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Re: [time-nuts] 4046 replacement

[Jim Harman]

While we are on the subject of the 74HC4046, I would like to point out a
confusing error in the TI datasheet for this part, found at
http://www.ti.com/lit/ds/symlink/cd74hc4046a.pdf

The waveform diagram for Phase Comparator 3, Fig. 7 on p. 5, has inverted
waveforms for PC3out and VCOin. PC3out should rise at the leading edge of
SIGin and fall at the leading edge of COMPin. The corresponding diagram in
the NXP/Phillips datasheet, Fig. 11, is correct.

On Wed, Apr 18, 2018 at 5:28 AM, Clint Jay <cjaysh...@gmail.com> wrote:

> Why not try one, the 74HC4046 is pin compatible I think, you may need to
> make some changes to use the '7046 version but you can then make a value
> judgement if the flaw had in fact mainfested itself as a problem in your
> design?
>
>
--Jim Harman
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[time-nuts] General Recommendation?

[AC0XU (Jim)]

I would like to make time stability measurements of various clock sources over 
a time range from 0.1 sec to 1000 sec and down to as much below 10^-12 as I can 
afford. Mainly I am interested in 10 MHz but also would like to be able to test 
stability and phase noise of synthesizers at higher frequencies (up to maybe 
300 MHz or so).

I do not have a hydrogen maser and I am aware of the need for a stable 
reference clock.

My question is what device would be best for this purpose:

1) Agilent 53230A

2) HP 5370B

3) Timepod (and is it possible to purchase one and if so how?)

4) Some other device such as has been mentioned in other postings (W.J. Riley, 
etc.)

My supposition is that #1 and #3 cost about the same and #2 is considerably 
cheaper. All three are supported by  Timelab.

Don't think that I can afford the Microsemi 5120A or 5125A.

Not understanding the tradeoffs, I would appreciate some advice.

Thanks!

Jim


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Re: [time-nuts] Environmental sensor recommendations

[Jim Harman]

I would like to put in a good word for the DS18B20 temperature sensor. It
consumes very little power, uses the "1-Wire" protocol, and is available
pre-wired in a variety of configurations, for example this
https://www.adafruit.com/product/381
and this
https://www.adafruit.com/product/642

resolution is 12 bits, .0625 C, range -55 to +125 C.

You can connect a bunch of them in parallel on the same data pin if you
want to measure temperature at different locations

There is a pretty good 1-wire library for the Arduino.

On Thu, Apr 5, 2018 at 7:19 PM, Mark Sims <hol...@hotmail.com> wrote:

> Digital temperature sensors have some advantages (like nice factory
> calibration),  but also so issues.   The IIC/SPI ones need to be mounted to
> a PCB and also have quite a bit of thermal mass.  They also need 4-6 wire
> cables.  They are hard to attach directly to a point that you want to
> monitor.
>
> The advantage of thermistors is that they are small,  cheap, readily
> available with leads attached, and only require a two wire cable.   You can
> easily tape them to whatever point you want to monitor.
>
> The ADT7420 is $8 a pop + PCB + assembly + cable.  Decent thermistors can
> be had for less than a buck.
>
> --
>
> >  Check out ADT7420:
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-- 

--Jim Harman
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Re: [time-nuts] WWV or Net Clock controlled oscillator

[Jim Harman]

Or if you want a bit more of a challenge, you might consider the DS3231
https://datasheets.maximintegrated.com/en/ds/DS3231.pdf

This is a full-featured real time clock with a TCXO. It has a programmable
32KHz or 1 pps output. You can trim the frequency digitally via an I2C port
in increments of about 0.1 ppm.It comes in a small package but you can get
the Chronodot, a breakout version with 0.1" headers from Adafruit and
elsewhere:
https://www.adafruit.com/product/255

You can use the Chronodot by itself or hook it to an Arduino to access the
full range of features.


>
-- 

--Jim Harman
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Re: [time-nuts] accurate 60 hz reference chips/ckts

[Jim Harman]

On Thu, Dec 14, 2017 at 10:53 PM, Bob kb8tq <kb...@n1k.org> wrote:

>
>
> Of course this *assumes* an electronic approach. Given that it’s moving
> pretty slow and you
> only are looking at fractions of a millisecond, one *could* do an electro
> mechanical design …...
>
> Bob
>
> There is interesting background on power grid frequency/time adjustment
procedures here
https://en.wikipedia.org/wiki/Utility_frequency#Time_error_correction_(TEC)

and here
https://en.wikipedia.org/wiki/Electric_clock#Accuracy
-- 

--Jim Harman
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Re: [time-nuts] accurate 60 hz reference chips/ckts

[Jim Harman]

Since the power line has the desired long term stability but is poor on the
short term, I wonder if a solution might be to use it as the reference for
a "power line disciplined oscillator."

You would want a filter time constant of several hours in the control loop
to smooth out the variations in the 60 Hz.

Or it might be easier to rip the guts out of the Radio Shack clock, just
keeping the display, and drive the display with an Arduino and a DS3231 RTC
chip as the reference.

On Thu, Dec 14, 2017 at 4:05 PM, Hal Murray <hmur...@megapathdsl.net> wrote:

>
> apollo...@gmail.com said:
> > Want to provide an accurate  (relatively accurate) 60 hz reference to the
> > chip.   Some room inside for custom modifications.  Does a TCXO or
> similar
> > exist in a small package that provides 60 hz ticks?
>
> I doubt if you will find a TCXO that puts out 60 Hz.  But it's only one
> chip
> to make a divider.  The trick is to do it in software rather than hardware.
>
> The real question is what sort of error pattern are you interested in.  The
> power company has good long term stability.  How good is your TCXO?  It
> would
> be fun to play with the numbers.  On the other hand, can you derive your 60
> Hz from a GPSDO?
>
> --
> These are my opinions.  I hate spam.
>
>
>
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-- 

--Jim Harman
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[time-nuts] Argo AS-210 frame

[jim stephens]

Does anyone have a lead on the oscillator in this frame as far as repair 
/ replacement?


A friend has one with all the plugins, and one extra spot.  If I 
understand it, he also has an 18ghz plugin to fit that.


But currently the oscillator seems kaput.  He's checked all of the fuses 
he could get to according to the manual, and is looking for two others 
that currently alude him.


If anyone has had one apart and has some words on the process of working 
on them, he said he had a hell of a time disassembling things.  Also 
there are only shards of part of the case, and he seems to think the 
sizes of the panels are custom, and we can't rob from a donor TM-515.


Would appreciate anyone who has worked on one to let us know.
thanks
Jim
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Re: [time-nuts] Allan variance by sine-wave fitting

[Jim Lux]

-Original Message-
>From: Magnus Danielson 
>Sent: Nov 27, 2017 2:45 PM
>To: time-nuts@febo.com
>Cc: mag...@rubidium.se
>Subject: Re: [time-nuts] Allan variance by sine-wave fitting
>
>Hi,



>
>There is nothing wrong about attempting new approaches, or even just 
>test and idea and see how it pans out. You should then compare it to a 
>number of other approaches, and as you test things, you should analyze 
>the same data with different methods. Prototyping that in Python is 
>fine, but in order to analyze it, you need to be careful about the details.
>
>I would consider one just doing the measurements and then try different 
>post-processings and see how those vary.
>Another paper then takes up on that and attempts analysis that matches 
>the numbers from actual measurements.
>
>So, we might provide tough love, but there is a bit of experience behind 
>it, so it should be listened to carefully.
>



It is tough to come up with good artificial test data - the literature on 
generating "noise samples" is significantly thinner than the literature on 
measuring the noise.

When it comes to measuring actual signals with actual ADCs, there's also a 
number of traps - you can design a nice approach, using the SNR/ENOB data from 
the data sheet, and get seemingly good data. 

The challenge is really in coming up with good *tests* of your measurement 
technique that show that it really is giving you what you think it is.

A trivial example is this (not a noise measuring problem, per se) - 

You need to measure the power of a received signal - if the signal is narrow 
band, and high SNR, then the bandwidth of the measuring system (be it a FFT or 
conventional spectrum analyzer) doesn't make a lot of difference - the precise 
filter shape is non-critical.  The noise power that winds up in the measurement 
bandwidth is small, for instance.

But now, let's say that the signal is a bit wider band or lower SNR or you're 
uncertain of its exact frequency, then the shape of the filter starts to make a 
big difference.  

Now, let’s look at a system where there’s some decimation involved - any 
decimation raises the prospect of “out of band signals” (such as the noise) 
aliasing into the post decimation passband.  Now, all of a sudden, the 
filtering before the decimator starts to become more important. And the number 
of bits you have to carry starts being more important.  And some assumptions 
about noise being random and uncorrelated start to fall apart.


It actually took a fair amount of work to *prove* that a recent system I was 
working on
a) accurately measured the signal (in the presence of other large signals)
b) that there weren’t numerical issues causing the strong signal to show up in 
the low level signal filter bins
c) that the measured noise floor matched the expectation
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Re: [time-nuts] Why discipline Rubidium oscillator?

[Jim Harman]

On Mon, Nov 20, 2017 at 7:14 PM, Jerry Hancock <je...@hanler.com> wrote:

>   Have to do a cost/benefit analysis for the wife...


I hope she is not the type of person who sets her watch 5 minutes ahead so
she will arrive on time!
-- 

--Jim Harman
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Re: [time-nuts] How good is your ADEV at 10E7 seconds? :)

[Jim Palfreyman]

Approximately 6% of pulsars "glitch" and yes these (typically young)
pulsars are poor time standards. The glitching is most likely caused by
unpinning of vortices in the superfluid outer core. This causes a momentum
transfer from the core to the crust - and a speed-up. The Vela pulsar (freq
of ~11 Hz) is the most famous of the glitching pulsars as it glitches
regularly (approximately every three years). The last glitch of Vela (Dec
2016) had a deltaF/F of about 1.4E-6.

However millisecond pulsars are completely different. They spin at hundreds
of Hz, typically don't glitch, and PSR J0437-4715 will give many atomic
clocks a run for their money. It has an error in its period (5.75 ms) of
9.9E-17 and an error in its period derivative of 9E-26. The idea was to
monitor an array of millisecond pulsars and use this to detect
gravitational waves. For many years it was a race between LIGO and the
pulsar array to find GW. LIGO won.

Incidentally, LIGO has looked for GW coming from a pulsar. Vela was chosen
as its frequency is in the LIGO sweet spot. Nothing was found however (
https://arxiv.org/pdf/1104.2712.pdf) - but this was 7 years ago.


Jim





On 18 November 2017 at 13:24, Bob kb8tq <kb...@n1k.org> wrote:

> Hi
>
> There are a number of papers on pulsars as time standards. The gotcha
> in the observed data (that has been measured over long time periods) has
> been random frequency jumps. Put another way, 10 million seconds and
> beyond *is* the problem. It’s going to take a *lot* of monitoring for a
> very long
> time to convince people that a specific pulsar is a good idea.
>
> Bob
>
> > On Nov 17, 2017, at 8:54 PM, Hal Murray <hmur...@megapathdsl.net> wrote:
> >
> >
> > Context is the what-next portion of a recent LIGO talk.  For those of you
> > that missed it (or didn't pay enough attention), on Aug 17th, they got
> good
> > data from a pair of neutron stars.  1.7 seconds later, the Fermi
> satellite
> > got a gamma ray burst.  Within a day, the optical guys had found a new
> spot.
> > Over the next days and weeks, they got data over the whole spectrum,
> radio to
> > X-rays.  (There were 70 observatories lined up to pounce.  Everybody
> wanted
> > in on the action.)
> >
> > LIGO only works for roughly the audio spectrum.  At the low and high
> ends,
> > the noise goes up.  Lots of people are working on how to build gear that
> will
> > work at other wavelengths.
> >
> > One proposal is to monitor pulsars.  There might be stuff leftover from
> the
> > big bang with a period of a year or so.  If you can get good timing from
> a
> > pulsar, you might be able to see it.  I suspect that will take "good"
> timing
> > to a scale that would astonish most time-nuts.
> >
> >
> >
> > --
> > These are my opinions.  I hate spam.
> >
> >
> >
> > ___
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Re: [time-nuts] Discussion of precise time and frequency measurement

[Jim Harman]

On Mon, Nov 13, 2017 at 12:32 PM, Gregory Beat <w...@icloud.com> wrote:

>  As a second’s error in time will be about a nautical mile in US
> latitudes, I wonder if anyone has measured with GPS, how good the original
> surveys were?
>
> Sent from iPad Air
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I think one nautical mile per second is a bit off:

86,400 sec/day
Earth's circumference at lat. 41 is about 16,200 nautical miles, so it's
about 16200/86400 or 0.187 mi/sec

There is an interesting book "Longitude by Wire" by Richard Stachurski that
describes efforts in the mid 19th century to improve the accuracy of
surveys and determine the precise position of North America relative to
Europe.

This culminated in the use of pulses on telegraph lines to transfer
observatory time to remote stations. With this technique, very careful
measurements, and mathematical advances they were able reduce the longitude
uncertainty to less than 10 feet.

-- 

--Jim Harman
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Re: [time-nuts] Holdover, RTC for Pi as NTP GPS source

[Jim Harman]

On Thu, Nov 2, 2017 at 9:04 AM, Chris Caudle <ch...@chriscaudle.org> wrote:

>
>
> That sounds like you just designed the worst GPSDO ever.
>
> --
> Chris Caudle
>
> Yes but the price and power consumption are right. I guess it all depends
on your application...
-- 

--Jim Harman
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Re: [time-nuts] Holdover, RTC for Pi as NTP GPS source

[Jim Harman]

On Wed, Nov 1, 2017 at 7:21 PM, MLewis <mlewis...@rogers.com> wrote:

>
> And the DS3231 has:
> - a 32K output, and
> - an Active-Low-Interrupt/SQW output that can be set to PPS.
> It's unclear to me how to sync the DS3231 PPS to the GPS PPS, or if that
> can be done.
>
>
>
The DS3231 has an 8 bit register that will change its frequency in
increments of about 0.1ppm. Thus you could discipline it to get its pps
aligned with your reference.

With an adjustment range of +/- 127, that's a maximum offset of 12.7 ppm.
In the worst case you would have to move its pps 0.5 sec, which by my
calculation would take about 41.667 seconds or about 11.5 hours.

-- 

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Re: [time-nuts] OCXO Vectron 218Y44442

[Jim Harman]

Sorry, this image
http://www.patoka.ca/Vectron-218Y2/IMG_20171015_193511542.jpg

On Mon, Oct 16, 2017 at 6:22 PM, Jim Harman <j99har...@gmail.com> wrote:

> In your image ...125 it looks like there is a cold solder joint near the
> bottom right, in the second "column" of pads, 3 pads up from the bottom.
>
> On Mon, Oct 16, 2017 at 4:10 PM, Vlad <t...@patoka.org> wrote:
>
>>
>> Hello,
>>
>> I am wandering if anybody observe the behavior for OCXO, when its stop to
>> reproduce the signal, and the only way to return it back to business is
>> little mechanical stress.
>>
>> I have TWO of such OCXO. One of them is Austron 11.2 Mhz. And another one
>> is Vectron model 218Y4442 9.8304Mhz
>>
>> In case with Vectron, I even disassemble it (to whom who brave here is a
>> pictures):
>>
>> http://www.patoka.ca/Vectron-218Y2/
>>
>> Then as I connect it to the PS, I realize it start to reproduce the
>> signal again ! Before this it was nothing ! I tried different PS before to
>> open this "can" as a last resort.
>>
>> For the Austron - I didn't disassemble it. Instead I just kick it a
>> little bit. And immediately after that, it start to produce the signal !
>>
>>
>> --
>> WBW,
>>
>> V.P.
>> ___
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>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
>
>
> --
>
> --Jim Harman
>
>


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Re: [time-nuts] OCXO Vectron 218Y44442

[Jim Harman]

In your image ...125 it looks like there is a cold solder joint near the
bottom right, in the second "column" of pads, 3 pads up from the bottom.

On Mon, Oct 16, 2017 at 4:10 PM, Vlad <t...@patoka.org> wrote:

>
> Hello,
>
> I am wandering if anybody observe the behavior for OCXO, when its stop to
> reproduce the signal, and the only way to return it back to business is
> little mechanical stress.
>
> I have TWO of such OCXO. One of them is Austron 11.2 Mhz. And another one
> is Vectron model 218Y4442 9.8304Mhz
>
> In case with Vectron, I even disassemble it (to whom who brave here is a
> pictures):
>
> http://www.patoka.ca/Vectron-218Y2/
>
> Then as I connect it to the PS, I realize it start to reproduce the signal
> again ! Before this it was nothing ! I tried different PS before to open
> this "can" as a last resort.
>
> For the Austron - I didn't disassemble it. Instead I just kick it a little
> bit. And immediately after that, it start to produce the signal !
>
>
> --
> WBW,
>
> V.P.
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> and follow the instructions there.
>



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Re: [time-nuts] Resoration of 5065A - continued...

[Jim Harman]

On Mon, Sep 11, 2017 at 9:36 AM, paul swed <paulsw...@gmail.com> wrote:

> I would simply slap a 741 into position to see how it behaves.
> Also check those zeners for +/- 14.7V. They go bad.
> Regards
> Paul
> WB8TSL
>
> ... but leave the pins that the 709 uses for external frequency
compensation (1, 5, and 8 on the can or mini-DIP) unconnected. The 741 has
internal frequency comp and uses pins 1 and 5 for an optional offset null
instead.


--Jim Harman
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[time-nuts] Tsunami detection via GPS

[Jim Palfreyman]

Some here may find this of interest.

http://www2.unb.ca/gge/Resources/gpsworld.february08.pdf


Jim Palfreyman
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Re: [time-nuts] PLL book 3rd edition

[Jim Sanford]

When will it be available??

Jim

wb4...@amsat.org



On 8/18/2017 4:17 PM, Dr. Ulrich L. Rohde via time-nuts wrote:

Yes, and there is a lot of useful material in place including CMOS  and related 
new topics and update on numerical controlled oscillators . Thanks, Ulrich

Sent from my iPhone


On Aug 18, 2017, at 2:58 PM, David Bengtson <david.bengt...@gmail.com> wrote:

That's good news. It would be good to have a single reference for noise 
correlation.

Dave


On Tue, Aug 15, 2017 at 7:04 AM <ka2...@aol.com> wrote:
   Good Morning all ,
  
yes , it became non trivial but Enrico agreed to take over the old chapter 2. He thinks I do not use IEEE norm  abbreviation and the noise correlation part did not exist 20 years ago.And many new and important things  So I thing we are settled.
  
Thanks, Ulrich
  
In a message dated 8/14/2017 9:10:45 P.M. Eastern Daylight Time, david.bengt...@gmail.com writes:

Ulrich - Did anyone ever agree to help update this?

Regards

Dave


On Fri, Mar 11, 2016 at 3:13 PM, KA2WEU--- via time-nuts <time-nuts@febo.com> 
wrote:

Why don't you look at the outline to determine what might be  needed or
missing .

Ulrich




In a message dated 3/11/2016 11:09:51 A.M. Eastern Standard Time,
att...@kinali.ch writes:

Hoi  Ulrich,

On Mon, 7 Mar 2016 19:52:58 -0500
KA2WEU--- via time-nuts  <time-nuts@febo.com> wrote:


I have published the following  book

" Microwave and Wireless Synthesizers: Theory and  Design, Ulrich L.

Rohde,

John Wiley & Sons, August 1997,  ISBN  0-471-52019-5."

[...]

As I am more or less now in  microwave technology and less in  PLL IC's,

I

hate to see this  standard textbook disappear Who can help or  want

to

take  over?

Da ich sowieso für mich was grösseres über  Zeit/Frequenzmessung
amzusammenstellen bin, und da PLL's grundsätzlich auch  dazu gehören,
wäre ich interessiert. Mein Problem dabei ist, dass ich von  der
praktischen Seite aber kaum eine Erfahrung habe und für mich  alleine
die Arbeit mit ziemlicher Sicherheit zuviel wäre. Aber es wäre  möglich,
dass ich zum Beispiel mit Magnus zusammen und vielleicht der Hilfe  von
ein paar anderen time-nuts und/oder Enrico etwas auf die Beine stellen
könnte.

Was wären denn die Dinge, welche für dich, in ein Update rein  müssten?

Gruess aus Saarbrücken

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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---
This email has been checked for viruses by Avast antivirus software.
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Re: [time-nuts] SOPHOS discussion of GPS jamming and eLoran

[jim stephens]

On 8/9/2017 12:15 AM, Martin Burnicki wrote:

Dave B via time-nuts wrote:

Or...

http://bit.ly/2hGKTgXThat goes to:-

There are 2 problems I see with this kind of link:

1.) A user doesn't see where the link takes him before he has clicked on
the link, so he can easily be taken to a "bad" web site.

Bitly has a feature to preview the link destination.
For example, for http://bit.ly/2hGKTgX add a plus character 
http://bit.ly/2hGKTgX+


You get this information with the + version of the link:

Cyberattacks on GPS leave ships sailing in dangerous waters – Naked Security
https://nakedsecurity.sophos.com/2017/08/07/cyberattacks-on-gps-leave-ships-sailing-in-dangerous-waters

bitly.com/2hGKTgX

<http://bit.ly/Wn2Xdz+>
Info copied from Bit.ly web site FAQ.

 There were some "preview shortened link" sites, but you'd have to 
trust one of those to use that approach.


When I have a link like this I wish to expand, I use linux command line 
/ curses browser lynx.  No way to infect anything with it, and view all 
the indirections as they pop up.


I agree, I seldom bother with the current malware / security 
environment, better to do that than risk it.  And I always tell anyone 
who asks me for advise as you do, skip it, unless you really know what 
you are doing, or you will get pawned.


thanks
Jim
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Re: [time-nuts] RS232 output on a 53181A

[Jim Harman]

Well ASCII * is 2a in Hex, p is 70 so that seems an unlikely substitution
for a failing EPROM.

But 0 is 30 Hex, only one bit different from p.

On Wed, Jul 12, 2017 at 10:39 AM, Angus <not.ag...@btinternet.com> wrote:

> Hi,
>
> I've just been using an Agilent 53181A, but the serial output is not
> quite what I had expected. On the 53131A's that I've used the
> placeholder character on the RS232 output is an asterisk, but with
> this unit it is a lower case 'p'. Where the 53131A sends '2,*** u',
> this 53181A send '2,ppp u'. The only references to a placeholder that
> I saw in the manuals referred to an asterisk.
>
> The firmware version is 4613.
>
> Anyway, just wondering if anyone knows if this is correct, or maybe
> it's just the EPROM starting to fail.
>
> Thanks,
> Angus.
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--Jim Harman
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Re: [time-nuts] The clocks at Windsor Castle, UK

[jim stephens]

On 6/16/2017 3:31 PM, Bob kb8tq wrote:

Hi

They have been a novelty item just about as long as people have made clocks.
Exactly what they do or do not have for adjustment capability would be very much
a “that depends” kind of thing. There must be some method of getting the beast
up to sync. It *could* be pretty involved.

Bob
My father and I were @ a Costco quite some time ago and there was a very 
nice clock with full Westminster chimes & moon phase. Drove the wife 
nuts that we stood around fiddling with it to get it set properly and 
back in phase with the other dials.


One of those things that sticks in your gut sometimes if you're a time 
nut.  My dad was my original time nut.  He found out that he could take 
pocket watches apart when he was a kid and get them running again (1930s).


Fathers Day plug as well.  Miss him a lot
thanks
Jim

On Jun 16, 2017, at 6:02 PM, Hal Murray <hmur...@megapathdsl.net> wrote:


kb...@n1k.org said:

One thing that may be missing is that the clocks involved also keep track of
other things (date, lunar phase, sunrise / sunset …). Forcing them to gain
or loose a day might mess some of that  up.

I haven't worked with that sort of clock.  I would expect they would have
some mechanism to set the clock back without damaging things.  Do they?


--
These are my opinions.  I hate spam.



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Re: [time-nuts] BTTF : Austron 1210-C Crystal Clock

[Jim Harman]

Thanks for the references, Tom. The clock portion must have been a 113.
Operation at 1 kHz would certainly explain the whine.

I also remember taking a peek inside the oven and seeing an impressively
large chunk of quartz.

On Mon, Jun 12, 2017 at 12:45 AM, Tom Van Baak <t...@leapsecond.com> wrote:

> Hi Jim,
>
> Maybe a version of this?:
>
> http://leapsecond.com/history/Benchmark.htm
>
> The audible (1 kc) whine was probably from the model 113 or 115. See if
> any of the following pages remind you:
>
> http://leapsecond.com/hpclocks/
> http://www.radiomuseum.org/r/hewlett_pa_frequency_divider_and_cl.html
> http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1959-11.pdf
> http://hpmemoryproject.org/wb_pages/wall_b_page_01.htm
> http://hpmemoryproject.org/news/2012/vintage_01.htm
>
> /tvb
>
>
>
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-- 

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Re: [time-nuts] BTTF : Austron 1210-C Crystal Clock

[Jim Harman]

On Sun, Jun 11, 2017 at 9:01 PM, paul swed <paulsw...@gmail.com> wrote:

> But perhaps whats magical gold is the Patek Phillipe clock movement. Just a
> guess.I hear they are quite annoying clunkers actually. I have never owned
> one but a fellow in Europe was telling me you can really here them tick.
>

In my first job back in 1973 I inherited a lab that included what must have
been an HP 100C frequency reference. It took up most of a rack and divided
down a 100KHz oscillator with cascaded injection-locked 10:1 multivibrators
that used metal octal-base tubes. The final frequency of 100 Hz drove a
beautiful clock that made a very audible whine when it was working. This
must have been an option because I don't see any reference to it in the
100C manual.

At the bottom of the rack was a Hammarlund radio to tune in WWV for
calibration.

IIRC the clock motor also drove an adjustable cam and microswitch. The
receiver's audio was fed through the switch. I think the idea was that you
could accurately measure the oscillator drift by adjusting the phase of the
cam until you could hear WWV's tick during the short time the switch was
closed.


-- 

--Jim Harman
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Re: [time-nuts] Poor man's oven

[Jim Harman]

On Tue, Jun 6, 2017 at 10:00 AM, Riley, Ian C CTR NSWC Philadelphia, 515 <
ian.riley@navy.mil> wrote:

> Is there a practical minimum for what voltage you can feed into AREF?
>

It is hard to find on the data sheet, but the minimum voltage for an
Arduino's AREF is the internal analog reference voltage - 1.1V for the Uno,
2.56V for the Leonardo or Micro. The 32U4 chip in the Leo and Micro has
options for differential analog input and gains of 10, 40, or 200 but they
are not supported by the Arduino IDE - you have to set the internal
registers directly to use them. Also the input amplifier is pretty slow.


-- 

--Jim Harman
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Re: [time-nuts] Next Aug 21 eclipse and time flow

[Jim Palfreyman]

Personally I go with the Nature article. The other papers look like they
are anomaly hunting because they have a known event.

Having said that, we have two H masers at our observatory in Hobart and we
have a system set up to measure their phase difference down to about 0.03
ns. I will report back any anomaly.

We, of course, are not in the path of the eclipse, however gravitationally
there is still an alignment. Just through the Earth.


Jim Palfreyman


On 29 May 2017 at 08:17, iovane--- via time-nuts <time-nuts@febo.com> wrote:

> On august 21 2017 a solar eclipse will sweep USA from coast to coast. A
> lifetime opportunity to do coordinated experiments to check this or that.
> One of the questions that doesn't have a final answer yet is whether or not
> solar eclipses could affect the flow of time. They exist conflicting
> reports: Negative: http://www.nature.com/nature/journal/v402/n6763/full/
> 402749a0.html Positive: http://home.t01.itscom.net/
> allais/blackprior/zhou/zhou-1.pdf  http://home.t01.itscom.net/
> allais/blackprior/zhou/zhou-2.pdfPersonally I believe that the positive
> results were due to spurious responses of the atomic clocks to something
> else than gravity, or the clocks failed for some reason (e.g. jumping
> crystals then steered), or lower quality clocks had been sold to China.
> Anyway the recorded data do show an anomaly.As far as I know, no atomic
> clock tests are planned anywhere for that circumstance, but sincerely I
> don't believe this is the truth.Maybe the US time-nuts community, using its
> plenty
>  of atomic clocks, could give the final answer doing tests during the
> above mentioned eclipse.US time-nuts, what about the idea of doing
> yourselves a large scale coordinated test? Or do you actually believe that
> this question is already definitively closed?(Even discovering that atomic
> clocks might respond to someting else than gravity would be of great
> interest).Antonio I8IOV
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Re: [time-nuts] calculating stats with gaps in the data

[Jim Palfreyman]

If you do want to Fourier transform your data and you *do* have missing
data points, I can highly recommend the Lomb-Scargle periodogram. I put it
through its paces a while back. I took 3 sin waves of different periods and
amplitude of 1 and added them together. I used 1 data points. Then I
added Gaussian noise of various standard deviations. And I also removed
various amounts of data up to 90%.

The LSP still found the periods with noise of sd=5 and 90% of the data
gone. With sd=10 it could still find signal with 50% of the points removed.

I have some nice plots of all this if anyone is interested.

The main disadvantage of LSP is speed. It performs as O(n^2). This was a
huge disadvantage back in the 70s when it was published, but with today's
computing power it's not a problem. Unless you have 100 data points,
then patience is required.

Jim Palfreyman


On 26 May 2017 at 07:12, Michael Wouters <michaeljwout...@gmail.com> wrote:

> There are 'better' ways of handling gaps when calculating ADEV and
> siblings. Patrizia Tavela has a nice method: you pad out the time series,
> tagging missing points with NaNs say, and then if a difference contains a
> missing data point, you drop it. It works very well. I expect this is in
> Stable32. I think it's implemented in allantools. It's definitely
> implemented in the Matlab functions I wrote (tftools on GitHub).
>
> Cheers
> Michael
>
> On Fri, 26 May 2017 at 12:00 am, Tom Van Baak <t...@leapsecond.com> wrote:
>
> > Only Stable32 handles data gaps seamlessly. Give it a try (read the
> manual
> > for details).
> >
> > But also ask yourself how much gaps matter. Yes, they affect the accuracy
> > of your y-axis sigma scale and your x-axis tau scale. A few seconds every
> > 30 minutes is, what, a 0.1% error? That's like one pixel in a ADEV plot;
> > not significant.
> >
> > What I've done when I need a perfectly seamless data set is just
> > interpolate for rare and obviously missing phase data points. That keeps
> > the timescale intact. This is especially important if you plan to Fourier
> > transform the data: under no circumstances do you want to slip a sample
> in
> > that case.
> >
> > /tvb
> >
> > - Original Message -
> > From: "jimlux" <jim...@earthlink.net>
> > To: "Discussion of precise time and frequency measurement" <
> > time-nuts@febo.com>
> > Sent: Thursday, May 25, 2017 6:11 AM
> > Subject: [time-nuts] calculating stats with gaps in the data
> >
> >
> > > I'm looking at the python AllanTools package.. does it deal with gaps
> in
> > > the data series (e.g. I've got a series of phase and/or frequency
> > > measurements, 1 per second, but there's gaps of a few seconds every 30
> > > minutes or so)
> >
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Re: [time-nuts] TruePosition and Arduino Progress

[Jim Harman]

Sorry, I may have over-simplified. You sketch might look something like
this, assuming the PPS is connected to pin D2 and the rising edge makes the
second:

volatile boolean PPS_ReadFlag = false;

void setup () {
  ...

  attachInterrupt(digitalPinToInterrupt(2), serviceRoutine, RISING);

  ...
}


void serviceRoutine() {
  PPS_ReadFlag = true;
}



void loop () {
  while (!PPS_ReadFlag) {
while(Serial.available()) {
  --parse the next character and set a flag if the time is valid--
  }
   }

   if(timeValid) {
 -- update display or whatever --
   PPS_ReadFlag = false;
   }
}



On Sun, May 21, 2017 at 2:56 PM, Jim Harman <j99har...@gmail.com> wrote:

> Another way to do is to use the 1 PPS to trigger an interrupt on the
> Arduino. Look at the documentation for attachInterrupt(). In the interrupt
> routine, have it set a flag. The flag variable should be declared up front
> as volatile.
>
> Then in your main loop, do all your parsing then loop waiting for the flag
> to be set. When set, update the clock then clear the flag and repeat.
>
>
>
> On Sun, May 21, 2017 at 2:32 PM, Chris Albertson <
> albertson.ch...@gmail.com> wrote:
>
>> To add to my last message.
>>
>> You CAN collect all the data then parse it like you are doing if you
>> were to move to an interrupt driven serial port reader.   Each
>> character is then read by the interrupt handler anyplace in a large
>> circular buffer.   The parcer then reads out of the other and of this
>> buffer.
>>
>> The phlegm with the current code is the parse ingnores serial input
>> and will drop data, in also ignore the PPS and will as you found drop
>> pulses.
>>
>> Typically in real time processors like your that must be interrupt
>> driven or they must poll MANY times laster then the data arrives
>>
>> so as I wrote before, parsing the data stream one character at a tie
>> is in effect pooling the serial port much faster then characters
>> arrive.Adding a ring buffer and interrupts guarantees yo never
>> miss a character and certainly you need to interrupt in the PPS to
>> handle the case there three s serial data and the PPS at the same
>> time.
>>
>> The ring buffer is like you big string except you data data onto one
>> end at the same time as soured data off the other.  Hopefully the ring
>> buffer never has much data in it as the parser should be fathers then
>> the serial line.  BUT if a PPS happens then the parser in interrupted
>> while the display updates so th ring buffer might get filled up a
>> little.  But the ISR terminals the parser clears the buffer.
>>
>> On Sun, May 21, 2017 at 11:20 AM, Chris Albertson
>> <albertson.ch...@gmail.com> wrote:
>> > The problem is that you get the ENTIRE string then parse it.  This is
>> > not going to work well as you found out.   Your CPU spends almost the
>> > entire time waiting for characters to come in slowly off the serial
>> > line.  You are just waiting on bits and wasting CPU cycles
>> >
>> > What you need to do is parse one character at a time.   I bet your
>> > parser reads one character at a time from the string.   Have it read
>> > one character at a time directly from the serial port.   (Use a state
>> > machine.  It will work for such a simple  job as this)
>> >
>> > Yes if your CPU was MUCH faster your plan could work.  But on some
>> > GPSes the data never has a break.   You are trying to do ALL the work
>> > in the break but actually most of the down time when you should be
>> > working is between the characters.There is not a lot of work a
>> > finite state machine needs to do between characters, just move state
>> > based on a 'character class" table.   I you ever studied this
>> > formally, what you are building here is a "lexer" not a parcer.   The
>> > "Language" is not recursive and you never need to backtrack so it can
>> > be de-coded literally one character at a time.
>> >
>> > You DO really want the 1PPS to drive an interrupt.   Thisway you just
>> > continue working on the data stream and don't wait for the PPS.   When
>> > the PPS happens you do something QUICK. never do anything time
>> > consuming in the ISR or you will miss the next serial character.
>> > increment a seconds count and write two bytes the the LCD and exit
>> >
>> > On Sun, May 21, 2017 at 6:45 AM, Ben Hall <kd5...@gmail.com> wrote:
>> >> Good morning all,
>> >>
>> >> A quick update for those interested on my Arduino code developmen

Re: [time-nuts] TruePosition and Arduino Progress

[Jim Harman]

gt; >> clock message, an extstatus message, and a status message, it seems
> like it
> >> is still parsing when the 1PPS tick comes in...so it will display
> seconds as
> >> follows:  30, 31, 33, 34, 35, 36, 37, 39, etc...
> >>
> >> (If I don't wait for the 1PPS tick, it seems that my clock is one second
> >> fast.  I say "seems" to be fast, as the time agrees with an NTP clock
> on one
> >> computer, but seems a half second slow per GPSCon's time display on the
> >> Z3801.  I think I need to put up the antenna and check against WWV.)
> >>
> >> I've got one of those cheap little USB logic analyzers on order to
> figure
> >> out how much time elapses between the clock, extstatus, status, and 1PPS
> >> tick.  I may need something faster than an Arduino Uno to do this.
> >>
> >> I'm sure there is a way to do this with an interrupt...but I couldn't
> make
> >> that work yesterday.  More to follow.
> >>
> >> thanks much and 73,
> >> ben, kd5byb
> >> ___
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> >
> >
> >
> > --
> >
> > Chris Albertson
> > Redondo Beach, California
>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] GPS seconds conversion on an Arduino

[Jim Harman]

On Sun, May 14, 2017 at 9:25 AM, Ben Hall <kd5...@gmail.com> wrote:

> I think I can make the process work *if* the time library doesn't hold the
> answer.  (and I think it does)


The Arduino Time library can convert back and forth between numeric
year/month/day/hour/minute/second and a uint32 representing the number of
seconds since 1/1/1970. It does not take leap seconds into account however
so you would have to make an adjustment for them. It is reasonably well
documented and includes some handy conversion macros and examples.

As with other Arduino libraries, the source code is provided so you can see
how they did it.


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Re: [time-nuts] TruePosition on an Arduino

[Jim Harman]

On Sat, May 13, 2017 at 3:15 PM, Ben Hall <kd5...@gmail.com> wrote:

> I've been wanting to dive more into Arduino...so I figured I'd write my
> own interface program.  The last software class I took was FORTRAN...and
> then I did a little BASIC, so this C code stuff is all new to me and it's
> been a real learning experience.
>

I have done quite a lot of time-related work on the Arduino and here are
some suggestions:

-- Use the Arduino Leonardo or Micro board rather than the Uno. These use
the 32u4 processor rather than the Uno's 328p. The 32u4 has integrated USB
for the programming port, freeing up the hardware serial port to
communicate with a GPS without resorting to resource-intensive bit-banging
or interfering with the programming port. I prefer the Micro because its
pins are on 0.1" centers, making it compatible with a solderless breadboard.

-- For NMEA communication, use Mikal Hart's TinyGPS++ library, available at
http://arduiniana.org/libraries/tinygpsplus/
This handles all the parsing of both standard and non-standard NMEA
messages, You can use this in conjunction with the standard Time library to
convert GPS time to a unix-like date and time structure.

Contact me off-list if you want code examples.




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Re: [time-nuts] Three-cornered hat on timelab?

[Jim Harman]

On Thu, Apr 27, 2017 at 12:48 PM, Bob Stewart <b...@evoria.net> wrote:

> So, back to my question:  Where are the large ionospheric phase moves?
> This question has been causing me doubt since I started on this project.
> Or don't I still have enough data collected for this to happen?
>
> Bob
>

Bob, my test setup is a good deal simpler than yours, but attached is a
plot that I think shows the variations you are looking for quite clearly.
This is data from my homebrew GPSDO, which uses an Adafruit non-timing GPS
module and a run-of-the-mill surplus OCXO. The plot records the phase
comparator output over a period of about 1 week. The time constant of the
PLL is 1024 seconds and it is plotting the 5-minute average TIC values.

The full horizontal scale is 24 hours.

The vertical scale shows the data from several days with the traces for
successive days offset upwards by the equivalent of 40 nsec.

As you can see there is pretty good correlation of the phase error from day
to day and the wiggles migrate to the left a little, corresponding to the
23:56:04 siderial repeat time of the GPS constellation.This is with a
pretty good antenna location, under a shingle roof in the attic. I
calculate the day-to-day correlation at about 0.8.

Making the time constant larger increases the variations somewhat, because
the loop does not adjust as much, and they definitely get worse if I use a
less optimal antenna location.




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[time-nuts] Name of integral of timing residual

[Jim Palfreyman]

Folks,

I'm after the formal name of something (if it exists), and this group, if
any, should know.

Consider a plot of a timing residual vs time. Say a watch against a maser,
residual=watch-maser.

Now if I now plot the cumulative sum (think integral) of the residual,
that's going to give me an overall view of how the clock is performing over
time. (If it helps, think of PID controllers and how they work in the "I"
part.)

Now if you look at *motion* of an object over time, and you integrate its
acceleration you get velocity, integrate again you get displacement.
Integrate again and you get "absement" and again you get "abcity" (I only
recently discovered these terms).

Does the integral of a timing residual have a name, and does the integral
of *that* have a name as well?

Any thoughts?


Jim Palfreyman
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Re: [time-nuts] The ultraAtomic clock for home

[Jim Harman]

On Wed, Apr 5, 2017 at 7:30 AM, Bob kb8tq <kb...@n1k.org> wrote:

> I’m still a bit unclear on how many people will set up a wall of clocks
> running
> on a dozen or so time zones. Obviously the people making clocks are
> very much in favor of doing that
>

It's probably for flashy newsrooms, where they like to have clocks with the
time in London, Moscow, Tokyo, etc. It's nice to have all the second hands
jumping simultaneously!

The challenge there is to keep the clocks correct for summer time, which
changes on different dates in Europe and of course in the other direction
in the Southern Hemisphere.


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Re: [time-nuts] HP-59309A Clock counts only seconds

[Jim Harman]

The 14SO package is still in production, HEF4011B $0.37 ea from Digikey.
You should be able to get a breakout adapter if you need the DIP.

On Mon, Apr 3, 2017 at 7:43 PM, Jeremy Nichols <jn6...@gmail.com> wrote:

> I have a new-to-me HP-59309A HP-IB Digital Clock. The clock works on both
> the internal crystal oscillator and on an external 10 MHz standard (GPSDO).
> However, it counts only to 60 seconds and then repeats without updating the
> minutes digit. The TIME SET (FAST and SLOW) push-buttons work but again,
> the count will not update minutes and hours, only seconds. The DAY SET
> procedure works correctly for days and months. All the other switches and
> buttons do what they are supposed to do. Using my 10526T logic pulser I can
> force the minutes and hours counters to work. The power supply is in good
> condition (after replacement of a few components) and I see no other
> problems (yet).
>
> Tracing the clock signal through the logic circuitry brought me to U3 on
> the A4 board. This (U3) is a 4011 quad 2-input NAND gate in a 14-pin DIP
> package. It "connects" the seconds counter to the minutes counter and
> appears to have failed. One of the people on the email list <
> hp_agilent_equipm...@yahoogroups.com> commented that the 4000 series CMOS
> chips have a known limited lifetime. Since these parts are no longer in
> production, the writer expressed the concern that any parts I might find to
> buy may be DOA.
>
> Before I go hunting for parts, I'd appreciate hearing from anyone in the
> group who has experience with the 59309A Clock and/or the 4000-series CMOS
> family. In particular, are there modern equivalents to my 4011 chip? If the
> 4000's really do have a limited lifetime I'd rather use a substitute.
>
> Jeremy, N6WFO
>
>
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Re: [time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

[Jim Harman]

On Mon, Mar 20, 2017 at 4:14 PM, Mark Sims <hol...@hotmail.com> wrote:

> $3 for an  Arduino chip on a PCB with proto area from China (should have
> bought a lot more when they were available),$10 for a small ovenized 5V
> TTL output OCXO (also should have bought a lot more),  and $5 for misc
> parts (OK, beer money not included in the BOM).   Batteries not needed,
> powered off USB.


Hi Mark,

Did you use the Arduino's PWM output plus a LPF for the DAC, or a separate
DAC? If PWM, did you have problems with noise or sensitivity to the
USB-provided supply voltage?

Also I have found that not all computer USB ports can supply enough warm-up
current for a 5V OCXO. Or did you use a hefty USB charger and miss out on
the ability to get logging info back over the USB port?




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Re: [time-nuts] Smart Phone time display accuracy...?

[Jim Harman]

There are GPS apps for phones such as GPS Test Plus for Android that
display the time as received from the phone's GPS. I'm not sure if phones'
GPS modules produce a PPS output, but it would be cool if an app could send
a tick to the phone's speaker/headphones on the second.


> > Le 16 mars 2017 à 03:32, Mike Baker <mp...@clanbaker.org> a écrit :
> >
> > Hello, Time-nutters--
> >
> > Any thoughts on what the likely accuracy of smart phone time
> > displays might be?
>
> --

--Jim Harman
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Re: [time-nuts] Bye-Bye Crystals

[Jim Harman]

For other common crystal frequencies, let's not forget
3.579545 MHz and 4x that - NTSC TV color burst

and others listed here...
https://en.wikipedia.org/wiki/Crystal_oscillator_frequencies



On Tue, Mar 14, 2017 at 3:39 PM, Attila Kinali <att...@kinali.ch> wrote:

> On Tue, 14 Mar 2017 13:39:02 +0100
> Magnus Danielson <mag...@rubidium.dyndns.org> wrote:
>
> > Some claims that MEMS will kill crystals. It will surely eat a good
> > market share, but I think there is applications where MEMS is not mature
> > enough compared to crystals.
>
> MEMS is quite mature, it's just that it is playing a different game.
> While with quartz (and other piezoelectric crystals) we know how
> to design a crystal to frequency, things aren't so simple for MEMS.
> Simply scaling the design doesn't work apparently.
>
> What they instead do is to use the MEMS oscillator as a reference
> for a PLL locked VCO. As the whole thing is going to be a few mm^2
> of silicon anyways, reserving some µm^2 for the PLL and VCO don't
> cost much. And it gives the ability to "tune" the oscillator
> for the frequency needed after production (the same technique is used
> with "programmable" crystal oscillators). Of course, having a PLL,
> mostly a fractional-N PLL, causes a lot of spurs in the output,
> which can cause problems, depending on the application.
>
> The big promise of MEMS oscillators was, that they'd be cheaper (due to
> integration in silicon) and used less power. As far as I am aware,
> neither promise could be upheld. MEMS need a quite different production
> process than normal digital electronics, hence it's usually more economic
> to have the oscillator on a different die than the digital chip. As for
> power consumption, the low power MEMS are about at the same level as the
> low power 32kHz crystal oscillators (and also in the same frequency).
> One place where MEMS are exceedingly good is temperature characteristics.
> Silabs demonstrated an oscillator, which, prior to any compensation,
> exhibited only <5ppm shift over the full temperature range.
>
>
> As for the demise of single quartz crystal units, I think that is not
> going to happen any soon. It is rather that the economics shift. Most
> of the single crystals are used as reference oscillators for digital
> and analog/RF chips. Ie most these chips have an internal oscillator
> that uses an external crystal to drive their internall VCO+PLL.
> As the crystal frequency is dictated by the frequencies these chips
> have to generate, there is a kind of standardization going on due to
> the limited number of protocols that need special frequencies. Two very
> common frequencies are 12MHz, for USB, and 25MHz, for Ethernet.
> 16MHz is base for CAN, some Wifi chipsets and USB as well. Then there
> are a couple of frequencies that are related to GSM, UMTS and the various
> other telephone standards. There are maybe a handfull of these frequencies,
> which "everyone" needs (ie are used in many high volume products). These
> are
> the crystals we will be able around for the forseeable future. There are
> other frequencies that are less used, which you will still get, but need
> to pay more or are made to order. Frequencies for protocols that are
> not used much anymore, or can be easily generated from another frequency
> that is more common, are bound to die out (as has happend with all those
> UART crystals, which are only used in legacy systems or for historical
> reasons).
>
>
> For specialized applications, where the crystal is not directly interfaced
> to a chip that provides the oscillator, it is more convenient for the
> designer to just use a complete oscillator than to design his own
> oscillator
> with all the problems that it involves. Getting such a device reliable to
> work in production volumes is nothing an average engineer without prior
> experience in can just pull off. Heck, I design my stuff to use oscialltors
> instead of crystals, because that's one thing less I have to care about.
> But even with these oscillators, there is only a limited number of
> frequencies
> that are easy to get. Those are again the standard frequencies from above,
> and a couple of round numbers (like multiples of 10MHz)
>
>
> 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] Bye-Bye Crystals

[Jim Harman]

On Mon, Mar 13, 2017 at 6:05 PM, Jim Harman <j99har...@gmail.com> wrote:

> Some of the Arduino boards, the Leonardo for example, use ceramic
> resonators,


Sorry, the Leonardo does have a crystal. The original Uno had a resonator.


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Re: [time-nuts] Bye-Bye Crystals

[Jim Harman]

On Mon, Mar 13, 2017 at 4:53 PM, jimlux <jim...@earthlink.net> wrote:

> I think the Arduino, for instance, uses a crystal (and the oscillator
> electronics are inside the Atmel part)


You're right. Some of the Arduino boards, the Leonardo for example, use
ceramic resonators, which make them truly awful for timekeeping
applications.


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Re: [time-nuts] WTB: GPSDO

[Jim Sanford]

Glad you didn't fare any worse in the event.

Good luck and very 73,

Jim

wb4...@amsat.org



On 3/9/2017 3:45 AM, Jeff AC0C wrote:

We had a small tornado come through north of our house about 1/2 mile on 
Monday.  Really did a number on the antennas.  Only electronics impacted was my 
old Nortel GPSDO.  It’s pretty much deaf now, as far as I can tell.  The Nortel 
always had a hard enough time obtaining the initial lock in the past on 
startup, but since “the event” it’s been no joy.

So I’m in the market for a GPSDO.  Key application here is as a bench precision 
frequency reference.  Something with good composite noise performance close in.

If you have a suitable GPSDO in solid operational condition, kindly contact me 
off list.  Thanks!

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

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Re: [time-nuts] How good is the left end of your ADEV curve?

[Jim Palfreyman]

I can't recall what I said before, but it *has* been done in the backyard
before. There's good news and bad news. The good news is that all the
software for processing your data: coherent dedispersion, folding, moving
all arrival times to the solar system barycentre, Einstein delay, Shapiro
delay, fitting, analysis etc is open source. You need DSPSR, PSRCHIVE, and
TEMPO2 and a unix machine to run them on.

The bad news:

Vela had a declination of -45 10 35 which means it's not visible very often
for you northerners. The second brightest pulsar has a similar declination.
After that, forget it - they are too faint.

Observing of individual pulses requires around a 20+ m radio telescope with
a receiver cooled to 20K (at ~1400 MHz). However using the above software
you can fold your data on the latest pulse period (which I can provide if
needed) and this then brings things down to a possible level:

You'll need a dish that can track. One that is 2 m across might just work.
Frequency choice is important. The lower the frequency the stronger the
pulse, but also multipath scattering smears the pulse out. Around 1400 MHz
is a good choice for removing the scattering, but may be too faint for
small dishes. If you went with ~600 MHz that could work - but do check any
local RFI.

If you didn't track, but just waited for the pulsar to pass through the
beam, you'd get about 2 minutes of data. That *might* be enough to fold and
get a signal.

It'd be a long, but awesome, project to work on.

The really cool part is that Vela glitches (speeds up) in rotation ~3 years
by around deltaf/f =10^-6 and you could measure that. It just glitched in
December (and I was observing at the time!), so you have another 3 years to
get building.

As to timing, any half decent GPSDO would be fine.

Oh, almost forgot, you'd also need a sampler.


Jim Palfreyman



On 26 January 2017 at 13:58, Tom Van Baak <t...@leapsecond.com> wrote:

> > What can I do at home, to observe such processes? Or is it way beyond
> > any imagination to participate in any such experiments?
> >
> > Volker
>
> LIGO is a billion dollar experiment, involving thousands of PhD's so it
> will be some time until you can do that sort of stuff alone at home, or
> with your family.
>
> Jim Palfreyman has mentioned before what it would take to do Pulsar
> measurements as a home experiment. Search for the old threads or he can
> jump in to remind us why it can't or hasn't been done yet. See also the
> thread a month ago about a DIY H-masers since you'll want some of them on
> hand before you start.
>
> It's worth spending time reading anything about LIGO. The experiment is
> out-of-this-world clever, complex, sensitive. And it actually works! Unlike
> the particle physics tree, which seems to be nearing the end of bearing
> fruit, LIGO is at the very beginning of an entirely new way to study the
> universe.
>
> /tvb
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Re: [time-nuts] How good is the left end of your ADEV curve?

[Jim Palfreyman]

First, a picky - but important - point. There is a difference between
"gravity waves" and "gravitational waves". When you go to the beach and
watch the waves crash on the shore, that's an example of a gravity wave.

Now, onto the far more interesting topic of gravitational waves and my pet
topic, pulsars.

Pulsars most likely give off gravitational waves. The rotate at a rate
anywhere from 1/12 Hz to 716 Hz. The brightest (in a radio sense) and one
of the closest pulsars is the Vela pulsar which rotates at 11.18677266 Hz
(as of a few days back). This frequency is in the sensitivity bands of
Advanced LIGO and Advanced VIRGO, but the gravitational waves from Vela are
probably too "faint" to be detected. But there is still no harm in trying.


Jim Palfreyman



On 25 January 2017 at 16:15, Hal Murray <hmur...@megapathdsl.net> wrote:

> way way way left.
>
> Ray Weiss was the speaker at the Stanford Physics Colloquium today.  In
> case
> you don't recognize the name, he is one of the leaders of the LIGO project
> that detected gravity waves about a year ago.
>
> He's a good speaker with a neat topic.  He spent a lot of time giving
> credit
> to other people.
>
> One of the far-out future ideas he mentioned was collecting data on lots of
> pulsars.  If you could get good enough data, maybe you could see gravity
> waves wandering around the universe.  (Maybe leftover from the big bang.  I
> didn't catch that part.)
>
> The time scale is months or years.  Micro Hertz.  The unit for wavelength
> would be light-years.
>
> How long will it be before we need a gravity-nuts list?
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] Autodesk Eagle -- maybe they're listening

[Jim Pruitt]

Mike,  you are correct about Autodesk products being free to
students/faculty/and staff with proof of status.  A college/university
email would do that.

I retired from a medium size state university here in late spring.  My job
there was to purchase, set up, install/administer software and hardware,
and maintain some application servers including ones for Autodesk,
Solidworks, Matlab, and Oracle Primavera.  I had 2 Autocad labs consisting
of about 25 stations each.  We used Autodesk products because they were
free to universities as long as it was in a teaching capacity.  For that
reason facilities management could not use the educational version.
Autodesk and the cad labs took up over 75% of my time so 2 labs kept me
busy and I had 10 other pc labs to maintain on campus.  I assume that
because the product was free to us we were on the bottom of the food chain
as I ran into a bug with their product that cause our students to have to
sit for 20 minutes before the license server would issue them a license.
Keep in mind that classes only lasted 50 minutes!  Even though I hired a
third party VAR (value added reseller) for cad tech support.  Education was
all on their own so even my VAR could not help me resolve the problem.
They did manage to give me one name at Autodesk that I could contact and
push them from inside.  If it had not been for that I feel they never would
have taken the problem seriously.  Even at that it took 2 months to get it
figured out.  They did not fix the problem til the following year when a
new version was released.  Prior to the product being offered free I could
contact Autodesk and get support when needed.

In short,  Autodesk products are free to students and staff/faculty when
used for educational purposes.  I had to resort to forums and other avenues
to get tech support.

Good luck.

Jim Pruitt


On Mon, Jan 23, 2017 at 4:56 PM, Mike Suhar <msu...@woh.rr.com> 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] Temperature (environmental) sensors

[Jim Harman]

These
https://www.adafruit.com/products/381
are .0625C resolution, 1-wire interface (temp only)

This one
https://www.adafruit.com/products/642
has Teflon insulation, for use at higher temps

Or this one, Temp/humidity with I2C interface
https://www.adafruit.com/products/1293


On Tue, Jan 3, 2017 at 11:19 AM, Adrian Godwin <artgod...@gmail.com> wrote:

> All these (including the one I linked) seem to be 0.5C only.
>
> This one gets to 0.2C : http://www.ti.com/tool/hdc1010evm
>
> On Tue, Jan 3, 2017 at 4:09 PM, Paul Alfille <paul.alfi...@gmail.com>
> wrote:
>
> > If you don't mind using 1-wire sensors, there are many nice choices,
> like:
> >
> > http://www.embeddeddatasystems.com/Environmental-Sensors_c_44.html for
> > temperature/humidity/barometric pressure...
> >
> >
> >
> > On Tue, Jan 3, 2017 at 10:22 AM, jimlux <jim...@earthlink.net> wrote:
> >
> > > On 1/3/17 7:08 AM, Tom Van Baak wrote:
> > >
> > >> I have some high-end temperature and pressure instruments. But for
> > casual
> > >> use in my home and mobile timing lab I use Sparkfun Weather Stations.
> > The
> > >> old URL is:
> > >>
> > >> https://www.sparkfun.com/products/retired/10586
> > >>
> > >>
> > > Replaced by
> > > https://www.sparkfun.com/products/12081
> > > which doesn't have the USB.
> > >
> > > By the time you add a board with a processor, you're in the $50 range..
> > >
> > > I use these at work:
> > >
> > > https://www.lascarelectronics.com/easylog-data-logger-el-usb-rt/
> > > Well, actually I use the EL-USB-2-LCD.. which logs to internal memory
> and
> > > can't log/unload data at the same time and which requires a windows
> > program.
> > >
> > > That said, they work well, come with a traceable cal certificate, etc.
> I
> > > don't know that they do 0.1 degree (the data sheet says 0.5C, and I
> think
> > > that's the logging accuracy), and, well, humidity sensors are of
> dubious
> > > accuracy away from the middle of the range
> > >
> > > https://www.lascarelectronics.com/easylog-data-logger-el-usb-2-lcd/
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > It's USB, talk-only, one reading a second, temperature, pressure,
> > humidity
> > >> -- about as simple as you can get. Perfect for data logging along with
> > >> frequency standards, GPS, counters and such.
> > >>
> > >> But they don't make 'em anymore. My question is what similar
> > >> well-engineered, talk-only, serial or USB,
> temperature-pressure-humidity
> > >> sensors have you run across and could recommend? Not to be picky bit
> no
> > >> cheapo 1C or 0.5C sensors; 0.1C or better is ok.
> > >>
> > >> I know it's "easy" to throw one together with an Arduino, but I'm
> > looking
> > >> for something pre-packaged, something that reliably works,
> > out-of-the-box.
> > >> I have backup plans but hope someone on the list knows some products
> > they
> > >> have used and would recommend.
> > >>
> > >> We could extend the discussion to voltage and power monitors too. Or
> > some
> > >> kind of universal sensor TAPR project. But for now, let's just keep it
> > to
> > >> simple air / environmental sensing.
> > >>
> > >> Thanks,
> > >> /tvb
> > >> ___
> > >> time-nuts mailing list -- time-nuts@febo.com
> > >> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> > >> ailman/listinfo/time-nuts
> > >> and follow the instructions there.
> > >>
> > >>
> > > ___
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-- 

--Jim Harman
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Re: [time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

[Jim Harman]

You could try hooking up a transformer with a 20V secondary as an
autotransformer to reduce the line voltage.

On Fri, Dec 30, 2016, 9:09 PM Bob Stewart  wrote:

> If you can touch the heat sink for 2 seconds, you're made of sterner stuff
> than I am!  They run very hot.  It's a good idea to get a GPIB extender so
> your GPIB cable can clear the heat sink.  Somebody, can't remember who,
> worked up a nice looking conversion to a pair of switching supplies.  I
> bought a couple of the supplies from ebay, but that project hasn't shuffled
> to the top of the list, yet.  Maybe the next time I forget and reach back
> there and get burned...
>
> Bob
>
>
>
>   From: Dr. David Kirkby - Kirkby Microwave Ltd <
> drkir...@kirkbymicrowave.co.uk>
>  To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
>  Sent: Friday, December 30, 2016 5:58 PM
>  Subject: [time-nuts] Anyone (ideally in the UK) got a spare rotary knob
> for the 5370B TI counter?
>
> I bought a 5370B TI counter which arrived today. It needs a bit of TLC, but
> nothing too bad. But one of the rotary knobs is incomplete. Does anyone
> have a
> spare knob? Contact me off list if you do.
>
> I had one of these things about 10 years ago. I have forgotten how to
> drive it.
>
> It is running very warm. I can hold my fingers on the heatsink for only a
> couple
> of seconds - not a very scientific test I must admit.
>
> Obviously the mains voltage varies a bit, but it is usually well over the
> 230
> VAC we are supposed to be. I just measured it at 248 VAC. Unfortunately I'm
> right on top of the 11 kV transformer, so other properties around me
> probably
> get poorer voltage regulation, but a few less volts.
>
>
> Dave
>
>
> --
> Dr. David Kirkby Ph.D CEng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
> 6DT, UK.
> Registered in England and Wales, company number 08914892.
> http://www.kirkbymicrowave.co.uk/
> Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
>
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Re: [time-nuts] Measuring sidereal/solar time? Re: A Leap Second is coming

[Jim Palfreyman]

I don't think we could call it "amateur/semi-pro" but the millisecond
pulsar J0437-4715 would be perfect for this. Bright and precise.

Only for southern hemisphere people though.

:-)


Jim Palfreyman


On 30 December 2016 at 19:59, Anders Wallin <anders.e.e.wal...@gmail.com>
wrote:

> out of curiosity, are there any amateur/semi-pro experiments that can
> measure the length of the solar or sidereal day to sub-millisecond
> resolution?
> To reproduce data like this:
> https://upload.wikimedia.org/wikipedia/commons/5/5b/
> Deviation_of_day_length_from_SI_day.svg
>
> Something in the sky that goes "ping" every day - detected with a pointing
> accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
> satellite-dishes pointed at the sun and noise-correlation/interferometry??
>
> Anders
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Re: [time-nuts] Lady Heather for homebrew GPSDO

[Jim Harman]

On Sun, Dec 18, 2016 at 1:06 PM, Mark Sims <hol...@hotmail.com> wrote:

> Binary or NMEA you need routines like send_msg_start,  send item (like
> integer, float, double), send_msg_end.  For received messages you need
> things like get_message,  get_item_from_message, etc.  The code to do that
> is not much more complicated for a binary protocol or an ASCII one like
> NMEA.
>

One factor that leads me to prefer NMEA is that my GPS already produces it,
so all I would have to do for the satellite, time, and other GPS data would
be to send the NMEA sentences from the GPS to the host port, no parsing and
reformatting required. In order to inject GPSDO data into this stream, I
would have to implement an NMEA multiplexer and construct the new
sentence(s) as you describe above.Of course I would still need an NMEA
parser in order to interpret commands from the host, but in the Arduino
world there is TinyGPS++, a very handy open source library for this.

I see that although the Z3801A's SCPI messages would be pretty easy to
implement, there are several inconvenient or limiting aspects to this
interface. (please correct me if I am wrong on these)

--It does not stream data the way NMEA does, so the host has to keep asking
for data.

--As has been mentioned earlier, most of the responses have no identifier,
so both ends have to be careful not to get out of sync.

--The EFC value is given as an integer percent -100 to 100, so there is not
enough resolution to really tell what the DAC is doing.

-- It does not have the satellite position and C/N data that is reported in
the NMEA GSV sentence, so LH can't make its nice satellite plots.

One thing I like about the Z3801A's format is the way the TCOD message
includes brief status and alarm information, so the data doesn't get
clogged with routine data but the host can tell when to request detailed
information.


-- 

--Jim Harman
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[time-nuts] Lady Heather for homebrew GPSDO

[Jim Harman]

Hi all,

I have experimented with LH 5 just monitoring a GPS receiver and am very
impressed with the results.

As a next step, I would like to use LH to monitor a homebrew GPSDO, and I
think it would be easier to modify the GPSDO firmware to emulate an
existing device rather than customize LH to work with the logging data that
my system currently produces.

In addition to NMEA data from the GPS, my system can output the DAC and TIC
(phase error) values as well as the temperature, Since I control the
firmware, I can produce pretty much any data format as long as it is
clearly documented, but I would prefer a text-based rather than binary
protocol and not to have to reformat all the NMEA data.

Does this approach make sense, and if so which of the several standard
GPSDOs would it be best to emulate?

Thanks in advance for your insights

-- 

--Jim Harman
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Re: [time-nuts] Lady Heather Version 5 is now available

[Jim Littlefield]

Version 5.00 is working well with my 58503A, but I did find one annoying 
behavior. If LH is the active application, as in it has keyboard focus, I find 
my screen saver will not activate.


Jim WN1X
On 12/11/2016 11:45:10 AM, paul swed <paulsw...@gmail.com> wrote:
Mark
I am trying to use Heather with a z3801. I have tried numbers of
combinations of what should set the system to the Z receiver. But none seem
to work. It immediately brings up the help screen and I assume that says
the command is bad.
I have no problem making the TBolt work.
Wonder if you could please clarify the receiver command.
Other bad note. My lucky day I have a LT1180 bad rcvr drvr chip in the
z3801.
Its receiving but not transmitting. Yahoo fun time.
Regards
Paul
WB8TSL

On Sat, Dec 10, 2016 at 7:25 PM, Mark Sims wrote:

> The heather.cfg file has a com port setting (/1u) and a /rxa (receiver
> auto-detect) command line option setting which gets processed before the
> settings on the command line.
>
> Try editing heather.cfg file and change the /1u command to /0
>
> -
>
> > I started it under Windows XP SP3, with the option /rxx as I currently
> have my TBolt
> connected to another PC, but what I got was an error message saying :
>
> Error exit 10002: Can't GetCommState()
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[time-nuts] I am looking to measure phase jitter between two synchronized DDS signals

[Jim Potter]

I just posted this on the HP Equipment forum. Someone reading it 
there suggested I contact timenuts because what I want to do is 
effectively an accurate time stability measurement.


I am attempting to look at the phase jitter between two synchronized 
DDS rf sources, one at 3 Ghz and one at 750 GHz. My 10 Gs/s scope has 
way to much jitter to be useful. A vector voltmeter might be just the 
thing. I have had an HP 8508A VVM and would buy another one if it was 
useful, but it is rated only to 2 GHz. I also have an old PRD 2020 
with the 2021 head that is in working condition. It is rated to 2.4 
Ghz, but syncs on the 750 MHz signal and apparently passes the 3 GHz 
signal somewhat. I get a reading of about -40 dBm for +10 dBm in at 3 
Ghz. However, I do get a phase measurement that varies with the phase 
of the 3 Ghz signal corresponding to the changes I make in the output 
phase. The issue is the noise. I see about +/- 1 degree jitter in the 
phase reading on the panel meter. I also see a drift of 2 to 3 
degrees. I don't think the DDS units are the source of the drift, and 
I'd like to show that the phase noise is lower than what I am observing.


I don't know of any VVM that works at 3 GHz, beyond the out of spec 
use of my PRD unit. Using an oscilloscope is problematic because I 
have measured the trigger jitter on a 100 Gs/s Tektronix unit when it 
was brand new. It's about 3.5 ps RMS. A 3 GHz signal has a period of 
333 ps so that corresponds to 10 degrees. I see that Tek has a new 
scope with 70 GHz bandwidth and 200 Gs/s, but I don't think that is a 
big enough improvement over the 100 Gs/s unit. In any case even 
renting one of these is probably too expensive.


I would appreciate any suggestions for how to accurately measure the 
phase jitter. I have a Tektronix RSA 306A which has been handy, but 
I'm uncertain about how to use it to measure phase jitter. In any 
case, what really matters is not the jitter of the individual signals 
but the jitter in the phase difference between the two signals which 
are all derived from the same time base.


One obvious question is, if I can't measure it how can it matter? The 
answer is that each rf unit is a signal source for a section of 
linear accelerator. If the phase jitter is excessive, it will show up 
as loss of beam quality and current. It's a bit hard to set up a 
proton accelerator to see if the jitter is acceptable. I really need 
able to make a bench measurement to qualify the performance.


Thanks in advance for any suggestions.

Jim


James M. Potter PhD, Pres.
JP Accelerator Works, Inc.
2245 47th Street
Los Alamos, NM 87544

TEL:505-690-8701
FAX: 888-301-2833

mailto:jpot...@jpaw.com
http://www.jpaw.com

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[time-nuts] Sapphire oscillators

[Jim Palfreyman]

Anyone got any comments on this?

http://www.theleadsouthaustralia.com.au/industries/technology/worlds-most-precise-clock-set-for-commercial-countdown/


Jim Palfreyman
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Re: [time-nuts] Has anybody checked this? GPSDO in kit

[Jim Sanford]

Nice!

(I had one of those, 20 years ago . . . .)

73,

Jim

wb4...@amsat.org



On 10/23/2016 1:49 PM, William H. Fite wrote:

Bravo for boat anchors, Wes. I have a Collins R390 with a tuning gear train
so complex it has to go in every 3000 miles for an oil change.


On Sunday, October 23, 2016, Wes <w...@triconet.org> wrote:


On 10/22/2016 9:22 AM, Chris Albertson wrote:


You have to remember what this thing replaces.   In ham radio, some people
are using vacuum tube oscillators with mechanical variable capacitor
tuning.  Maybe some advanced rigs use gear drive on the capacitor shaft to
allow more exact tuning  This Si chip is considerably better then 1940's
technology.


I guess my WW-II vintage BC342 receiver (that I started with and still
own) was "advanced".  It has an extensive gear train for tuning.

On the other hand my two Elecraft K3s are full of DDS and microprocessors
but no variable capacitors.

Flex radios, are direct sampling SDR and newer ones offer GPS
stabilization.
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Re: [time-nuts] 1PPS to 32.768 khz

[Jim Harman]

On Thu, Oct 20, 2016 at 7:08 AM, Bob Camp <kb...@n1k.org> wrote:

> One problem with a PLL and a 1 Hz input are the values of components
> you get in the loop.
> The other issue is the cost of the VCXO that will get
> you to 32,768 KHz.
>

As I mentioned earlier, the DS3231 chip (about $6.50 qty 1 or $17.50 on a
breakout board) might be a reasonable approach for this. It is a
self-contained 32.768 KHz TCXO that lets you vary the frequency in steps of
0.1 ppm using its I2C interface. Left to its own devices, it measures the
ambient temperature and switches its on-chip capacitors in and out to
control its frequency.

It has both 1 PPS and 32,768 Hz outputs. Connected to an Arduino-class
processor, you could measure the time delay between its PPS and the PPS
from a GPS and tweak the oscillator accordingly, making a complete 32.768
KHz GPSDO including the GPS with just 3 chips.

And you get RTC functionality and battery backup circuitry thrown in for
free.


-- 

--Jim Harman
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Re: [time-nuts] 1PPS to 32.768 khz

[Jim Harman]

Hi Lee,

It's not exactly what you asked for, but for your clock you might give this
a try, or consider using the underlying DS3231 chip directly.

https://www.adafruit.com/product/255

It is basically a much more accurate and stable than usual 32KHz
oscillator, with a TCXO that you can actually tweak programatically with a
resolution of about 0.1 ppm.

On Tue, Oct 18, 2016 at 10:03 PM, Lee - N2LEE via time-nuts <
time-nuts@febo.com> wrote:

> First let me say this is first time I have posted to the group so go easy
> on me. :)
> Secondly I want everyone to know that you guys make me feel so NORMAL for
> wanting to use and understand accurate timing devices.
>
> I thought there was something seriously wrong with me now I know there are
> others
> affected with the same disease. hehe
>
> Now my questions.
>
> 1. Does anyone know of a device that will take a 1PPS GPS timing signal
> and generate a 32.768 kHz sine wave output ?
> I have big digital clock that uses an 8 bit micro processor and an
> external 32.768 crystal. Obviously the external crystal is
> awful for accuracy.
>
> I have searched every where using as many search terms as I can think of
> and can’t believe there is not a device that performs
> this function.
>
> I have found a couple of Epson RTC chips that might come close that 1pps
> but I don’t think that corrects the 32khz just the clock time.
>
> 2. 10 Mhz Freq Standard
> I am not in the same league as the majority of the list members and just
> starting to dabble in GPSDO stuff.
> I have tried to find a thunderbolt as a starting device but it appears
> those are either dried up or people want too much money.
>
> I wanted to get the opinion of anyone who has tried the Leo Bodnar GPSDO ?
> For the money it appears to offer a beginner a lot of features.
>
> Thanks and reading the daily digest of what you guys are working on.
> I have a feeling if I am not careful you guys could cost me a lot of
> money. hehe
>
>
> Lee
>
>
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-- 

--Jim Harman
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[time-nuts] Atomic Watch

[Jim Palfreyman]

Well I think there's a mistake or two here...

https://www.inverse.com/article/20497-john-patterson-atomic-ce
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Re: [time-nuts] Measure GPSDO stability with minimum resources?

[Jim Harman]

On Wed, Oct 5, 2016 at 6:46 PM, Bob Stewart <b...@evoria.net> wrote:

> What I'm really looking for is a way to do everything in the PIC.  I've
> been experimenting with saving the DAC value in a circular queue every 20
> seconds for 60 minutes, and plotting the difference value between the head
> and tail of the queue every second.  After posting this question, I took
> another look at the overall behavior and decided to cut the queue size down
> from 60 minutes to 5.


Hi Bob,

Unless the oscillator is still warming up, 5 minutes or even 60 is way too
short a time to look at aging. For aging, you will want to look at the
change in DAC values over several days at least.

Looking at the current value and one in the past will give you a feel for
what is going on, but then you are discarding all the intermediate data.
You really want to do a least squares fit using as many data points as you
can handle, Check Wikipedia under Linear Least Squares for an example.

What sort of phase detector are you using? If you want to see whether the
system is locked, you may be better off looking at the phase detector
signal.and declaring a lock if the low pass filtered phase error stays
within a pre-determined range.

-- 

--Jim Harman
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Re: [time-nuts] ADC sample voting algorithm?

[Jim Harman]

On Wed, Oct 5, 2016 at 7:45 PM, Nick Sayer via time-nuts <time-nuts@febo.com
> wrote:

> I notice periodically that the phase measurements seem “noisy.” You can
> see that over the course of several seconds the value doesn’t change, then
> it jumps a bunch and then comes right back.
>

Hi Nick,

At one point I had a problem with noisy phase readings where the "noise"
took the form of an occasional reading that was low by up to about 50
counts. These events were quite rare - less often than once per hour on
average. After much head-scratching, it turned out that I had an interrupt
conflict that sometimes caused the PPS interrupt to be delayed, Because the
ADC was triggered inside this routine, the analog signal had drooped a
little before the ADC was triggered.

I was able to completely solve this by setting up the ADC sample/hold and
conversion to be triggered directly by the PPS signal, thus eliminating any
dependency on the interrupt latency. The PPS still generates an interrupt,
but in the interrupt routine, all I have to do is wait for the ADC to
finish, clear the Done bit, and reset the trigger.


-- 

--Jim Harman
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Re: [time-nuts] time-nuts Digest, Vol 147, Issue 13

[Jim Stone]

Re: TNS-BUF Amplifier

--Jim Robbins wrote:

 Many thanks for your helpful TN work to John A. , Dr. Bruce and John M.
Ordered 3 pieces.

--
I second the thanks and ordered 2 pieces

--Jim Stone

On Wed, Oct 5, 2016 at 9:00 AM, <time-nuts-requ...@febo.com> wrote:

> Send time-nuts mailing list submissions to
> time-nuts@febo.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> or, via email, send a message with subject or body 'help' to
> time-nuts-requ...@febo.com
>
> You can reach the person managing the list at
> time-nuts-ow...@febo.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of time-nuts digest..."
>
>
> Today's Topics:
>
>1. Re: Need Time Help (Mark Spencer)
>2. TNS-BUF Amplifier (James Robbins)
>3. Re: Need Time Help (Chris Caudle)
>
>
> --
>
> Message: 1
> Date: Wed, 5 Oct 2016 07:35:21 -0700
> From: Mark Spencer <m...@alignedsolutions.com>
> To: Peter Torry <peter.to...@talktalk.net>, Discussion of precise time
> and frequency measurement <time-nuts@febo.com>
> Subject: Re: [time-nuts] Need Time Help
> Message-ID:
> <dbfc5aa1-67c3-4ddd-bb8f-ee398a7e0...@alignedsolutions.com>
> Content-Type: text/plain;   charset=us-ascii
>
> Yes I'd be curious in knowing more about this as well.  I've often
> observed time differences from other stations of several tenths of a second
> when running the JT modes on HF.  Although I am beginner at EME I have made
> a couple of EME (earth moon earth) JT65 contacts on VHF without taking any
> special measures to sync the time on a Windows XP machine beyond using the
> built in features of the operating system to sync to my own local time
> server which was in turned synced to the 1 pps output of a GPS timing
> receiver.
>
> I've also made FSK441 contacts (another related form of amateur radio
> digital communications) in the field without any time reference besides the
> free running clock in my Windows xp laptop.  If there is a significant
> performance improvement to be had with these modes by having time nuts
> levels of timing precision on my computers I'd be very interested to know
> more.
>
> All the best
> Mark S
>
> Sent from my iPhone
>
> > On Oct 5, 2016, at 6:18 AM, Peter Torry via time-nuts <
> time-nuts@febo.com> wrote:
> >
> > I must admit to being rather puzzled at the sub microsecond timing
> requirement as I use ntp to set the W7 clock in my computer and have not
> had any issues. In fact less than one second is OK for the usual two minute
> periods that are required to allow for the Faraday rotation. Although I use
> a GPSDO for a frequency reference I find JT software reasonably tolerant of
> frequency.  As I may be missing something I would welcome observations on
> how important the period timing requirement is, you never know I might get
> more contacts.
> >
> > Regards
> >
> > Peter
> >
> >
> >> On 05/10/2016 12:50, Graham / KE9H wrote:
> >> 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
> >
> > ___
> > 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.
> >
>
>
> --
>
> Message: 2
> Date: Wed, 5 Oct 2016 10:56:05 -0400
> From: "James Robbins" <jsrobb...@earthlink.net>
> To: <time-nuts@febo.com>
> Subject: [time-nuts] TNS-BUF Amplifier
> Message-ID: <01c301d21f18$9994aee0$ccbe0ca0$@earthlink.net>
> Content-Type: text/plain;   charset="us-ascii"
>
> Many thanks for your helpful TN work to John A. , Dr. Bruce and John M.
> Ordered 3 pieces.
>
>
>
> 73,
>
> Jim Robbins
>
> N1JR
>
>
>
> --
>
> Message: 3
> Date: Wed, 5 Oct 2016 10:19:10 -0500
> From: "Chris Ca

Re: [time-nuts] Measure GPSDO stability with minimum resources?

[Jim Harman]

On Wed, Oct 5, 2016 at 1:37 PM, Bob Stewart <b...@evoria.net> wrote:

> For my GPSDO, I need to calculate the OCXO aging for holdover projection
> purposes as well as get some figure of merit for the recent past of the
> OCXO stability.


Do you have a serial port or some way of generating a logging stream?

If so, one low-overhead way to track the aging is to compute an average DAC
value and periodically "print" the result to the serial port. I have found
that a 3-hour average works well for observing aging. Each second you
simply add the current DAC value to a Long and after 3 hours divide by
10800, print the result, reset the total, and repeat. It is helpful to also
include the current time. This could be extracted from the GPS NMEA data
 or simply be seconds since startup. If you separate the values with a Tab
and end each set of values with a newline, you can capture the data with an
attached PC, copy/paste to Excel, and analyze it there. The trend line
feature in Excel's chart will compute and display a least square fit to the
aging.

If you don't want to keep the monitor connected full time and you have some
extra RAM or preferably EEPROM, you can store historic average values in a
circular buffer and print one of the values every second. 288 bytes will
store 18 days worth of 16 bit 3-hour averages.

My system, based on the one posted here by Lars Walenius some time
ago,collects 144 sets of 5-minute averages (12 hours worth) and another 144
sets of 3-hour averages. It spits out one line of logging data each second.
The first part of each line has the current data, and the second part has
either one of the 5-minute sets or one of the 3-hour sets. So 5 minutes
worth of logging data has 300 lines, showing current data plus 5-minute
averages for the past 12 hours and 3-hour averages for the past 18 days.

All this, including the GPSDO code, fits comfortably in a 32u4-based
Arduino Micro, which has 32K of program memory, 2.5K of RAM, and 1K of
EEPROM.




-- 

--Jim Harman
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Re: [time-nuts] Caroliine .. I need to move on

[Jim Palfreyman]

Well I'm intrigued!


On 2 October 2016 at 15:53, Ian Stirling  wrote:

> going to the emergency place
> ___
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[time-nuts] 10Mhz TXCO for LTE-Lite?

[Jim Miller]

Did anyone implement an external 10Mhz TXCO for the Jackson-Labs LTE Lite?

I'm finally getting around to trying to get 10Mhz out of this with a low
enough impedance to drive a 50ohm cable.

Thanks

jim ab3cv
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Re: [time-nuts] DIY VNA design

[Jim Cotton]

The intersection of HP equipment && Time-Nuts && VNWA mailing lists is >>

At least two ;^)

Jim 
n8qoh


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

[Jim Stone]

Hi again,
The cable impedance measurement was in a different video (linked below) but
it can use the same HC14 TDR as in the first video. The concept is to just
put a pot on the end of the cable and adjust it until the reflection goes
away. Simple!

https://www.youtube.com/watch?v=Il_eju4D_TM

--Jim Stone


Hi Bob,
Take a look at this nice simple little one chip "TDR" and lesson on how to
use it to measure cable length and cable impedance. It uses a single AC14
(can use a DIP so no SMD needed) and gives a nice crisp 2 or 3 ns rise. The
AC family is nice fast logic and has been used in many Time-Nuts
application like cheap zero-cross detectors using the AC04.

https://www.youtube.com/watch?v=9cP6w2odGUc

Regards --Jim Stone

Bob Albert wrote:

 Well I got my adapter boards from China and managed to build my first SMT
project, a square wave generator for TDR use.  And it works!  The IC seems
to run hot so I used my IR temperature measurement device and it checks out
at about 37C, acceptable.  I can now drive a square wave at about 3 kHz
into 50 Ohms.  The rise time isn't very short but I must have not used the
best part for the generator.  Still, I can do some TDR experimenting as
long as the line isn't too short.
Thanks to all for the ideas and encouragement.  I didn't use a microscope,
mostly just a magnifier.  My tiniest soldering iron is a bit large but it
did the job.
Bob
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Re: [time-nuts] Subject: Re: Working with SMT parts (Bob Albert)

[Jim Stone]

Hi Bob,
Take a look at this nice simple little one chip "TDR" and lesson on how to
use it to measure cable length and cable impedance. It uses a single AC14
(can use a DIP so no SMD needed) and gives a nice crisp 2 or 3 ns rise. The
AC family is nice fast logic and has been used in many Time-Nuts
application like cheap zero-cross detectors using the AC04.

https://www.youtube.com/watch?v=9cP6w2odGUc

Regards --Jim Stone

Bob Albert wrote:

 Well I got my adapter boards from China and managed to build my first SMT
project, a square wave generator for TDR use.  And it works!  The IC seems
to run hot so I used my IR temperature measurement device and it checks out
at about 37C, acceptable.  I can now drive a square wave at about 3 kHz
into 50 Ohms.  The rise time isn't very short but I must have not used the
best part for the generator.  Still, I can do some TDR experimenting as
long as the line isn't too short.
Thanks to all for the ideas and encouragement.  I didn't use a microscope,
mostly just a magnifier.  My tiniest soldering iron is a bit large but it
did the job.
Bob
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Re: [time-nuts] Austron 2010B (disciplined OCXO) square wave conversion

[Jim Stone]

I don't have the manual but I'm sure if you pop the cover you can find a nice 
sine wave inside (that is being converted to square wave). Un-solder one of the 
square wave output BNCs and patch in the sine wave. Now you have analog and 
digital outputs!
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Re: [time-nuts] Q/noise of Earth as an oscillator

[Jim Palfreyman]

Hi Tom,

You said: "you need energy; you need energy loss; you need cycles over
which that loss repeatedly occurs."

With regard to the earth, where is the first one? Sure it was there at the
start when the solar system formed, but where is it now?

Jim


On 1 August 2016 at 12:16, Tom Van Baak <t...@leapsecond.com> wrote:

> Hal:
> > Is there a term other than Q that is used to describe the rate of energy
> loss
> > for things that aren't oscillators?
>
> Jim:
> > cooling (as in hot things)
> > discharge (as in capacitors and batteries)
> > leakage (as in pressure vessels)
> > loss
>
> Scott:
> > An irreversible process would be a better description versus energy loss.
> > Like joule heating (resistance, friction).
>
> Notice that these are all energy losses over time; gradual processes with
> perhaps an exponential time constant, but without cycles or periods. We
> know not to apply Q in these scenarios.
>
> But when you have an oscillator, or a resonator, or (as I suggest) a
> "rotator", it seems to make sense to use Q to describe the normalized rate
> of decay. So three keys to Q: you need energy; you need energy loss; you
> need cycles over which that loss repeatedly occurs.
>
> We use units of time (for example, SI seconds) when we describe a rate.
> But here's why Q is unitless -- you normalize the energy (using E / dE)
> *and* you also normalize the time (by cycle). No Joules. No seconds. So
> having period is fundamental to Q. It's this unitless character of Q (in
> both energy and time) that makes it portable from one branch of science to
> another. And if you measure in radians you can even get rid of the 2*pi
> factor ;-)
>
> Without controversy, lots of articles define Q as 2*pi times {total
> energy} / {energy lost per cycle}. To me, a slowly decaying spinning Earth
> meets the three criteria. It appears to follow both the letter and the
> spirit of Q.
>
> Bob:
> > ummm…. Q is the general term of rate of energy loss and we just happen
> to apply
> > it to oscillators in a very elegant fashion….
>
> Oh, no. Now we have both quality factor and elegance factor!
>
> /tvb
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Re: [time-nuts] Q/noise of Earth as an oscillator

[Jim Palfreyman]

> What about an ADEV/TDEV plot of the pulsar J0437-4715?

Very boring. It's a straight line from top left to bottom right. :-)

See page 5 of this: http://arxiv.org/pdf/1004.0115.pdf

Jim Palfreyman


On 29 July 2016 at 17:33, Azelio Boriani <azelio.bori...@gmail.com> wrote:

> What about an ADEV/TDEV plot of the pulsar J0437-4715?
>
> On Fri, Jul 29, 2016 at 12:39 AM, Jim Palfreyman <jim77...@gmail.com>
> wrote:
> > Hi All,
> >
> > Tom gave me a nudge to look here - I hadn't been following this thread.
> >
> > For those that don't know, I study pulsars and so the way we measure what
> > pulsars do could be relevant to this discussion.
> >
> > First, I have never heard of a Q measure when referencing a pulsar. I
> think
> > the key here is that it's not resonating as such. Rotating yes,
> resonating
> > no.
> >
> > Pulsars spin and slow down due to giving off energy (magnetic dipole
> > radiation). So in the pulsar world we mainly refer to spin frequency (F0)
> > and frequency derivative (F1). With some of the younger and more
> "erratic"
> > pulsars, F2 (and further) can be modelled.
> >
> > Here's some data on the Vela pulsar (hot off the presses - measured just
> > now):
> >
> > F0  11.1867488542579
> > F1  -1.55859177352837e-11
> > F2  1.23776878287221e-21
> >
> > Vela is young and erratic. Millisecond pulsars are outstanding clocks.
> > Here's the data for J0437-4715 - one of the most stable pulsars we know
> > about:
> >
> > F0  173.6879458121843
> > F1  -1.728361E-15
> >
> > I'm sure the "Q" of Vela would be pretty decent - but I can tell you now,
> > as a time-keeper, she's useless.
> >
> >
> > Jim Palfreyman
> >
> >
> >
> > On 28 July 2016 at 20:50, Tony Finch <d...@dotat.at> wrote:
> >
> >> Neville Michie <namic...@gmail.com> wrote:
> >>
> >> > The conical pendulum has a simple form of a weight on a string,
> instead
> >> > of oscillating in one plane as a conventional pendulum, it swings
> around
> >> > in a circular orbit in the horizontal plane. It has a definite
> resonant
> >> > frequency.
> >>
> >> I don't think it does have a resonant frequency, any more than the Earth
> >> does: the angular velocity of the pendulum is sqrt(g/h) where h is the
> >> height of the pendulum; give it more energy, it swings higher, so h is
> >> smaller, so the frequency is higher.
> >>
> >> Tony.
> >> --
> >> f.anthony.n.finch  <d...@dotat.at>  http://dotat.at/  -  I xn--zr8h
> >> punycode
> >> South Thames, Dover: Southwesterly 5 or 6. Slight or moderate. Rain or
> >> showers. Good, occasionally poor.
> >> ___
> >> 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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Re: [time-nuts] Q/noise of Earth as an oscillator

[Jim Palfreyman]

Hi All,

Tom gave me a nudge to look here - I hadn't been following this thread.

For those that don't know, I study pulsars and so the way we measure what
pulsars do could be relevant to this discussion.

First, I have never heard of a Q measure when referencing a pulsar. I think
the key here is that it's not resonating as such. Rotating yes, resonating
no.

Pulsars spin and slow down due to giving off energy (magnetic dipole
radiation). So in the pulsar world we mainly refer to spin frequency (F0)
and frequency derivative (F1). With some of the younger and more "erratic"
pulsars, F2 (and further) can be modelled.

Here's some data on the Vela pulsar (hot off the presses - measured just
now):

F0  11.1867488542579
F1  -1.55859177352837e-11
F2  1.23776878287221e-21

Vela is young and erratic. Millisecond pulsars are outstanding clocks.
Here's the data for J0437-4715 - one of the most stable pulsars we know
about:

F0  173.6879458121843
F1  -1.728361E-15

I'm sure the "Q" of Vela would be pretty decent - but I can tell you now,
as a time-keeper, she's useless.


Jim Palfreyman



On 28 July 2016 at 20:50, Tony Finch <d...@dotat.at> wrote:

> Neville Michie <namic...@gmail.com> wrote:
>
> > The conical pendulum has a simple form of a weight on a string, instead
> > of oscillating in one plane as a conventional pendulum, it swings around
> > in a circular orbit in the horizontal plane. It has a definite resonant
> > frequency.
>
> I don't think it does have a resonant frequency, any more than the Earth
> does: the angular velocity of the pendulum is sqrt(g/h) where h is the
> height of the pendulum; give it more energy, it swings higher, so h is
> smaller, so the frequency is higher.
>
> Tony.
> --
> f.anthony.n.finch  <d...@dotat.at>  http://dotat.at/  -  I xn--zr8h
> punycode
> South Thames, Dover: Southwesterly 5 or 6. Slight or moderate. Rain or
> showers. Good, occasionally poor.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] Q/noise of Earth as an oscillator

[Jim Harman]

On Wed, Jul 27, 2016 at 11:33 AM, Chris Caudle <ch...@chriscaudle.org>
wrote:

> Who has a globe on magnetic bearings in a vacuum chamber and will run the
> experiment for us?
>

The superconducting gyroscopes in the Gravity Probe B satellite did an
extraordinary job of eliminating frictional and other losses in a spinning
object, with a spin-down time constant of 15,000 years.

https://einstein.stanford.edu/TECH/technology1.html


-- 

--Jim Harman
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Re: [time-nuts] LSEM (Leap Second Every Month)

[Jim Palfreyman]

The idea is the same as my local telco and their main exchanges.

Every month they walk up to the main circuit breaker and cut the power to
the entire building. All the UPSs and diesel generators get tested in anger.

This leap second solution is the best I've heard so far.

Personally I now hate leap seconds because it ruins many hours of my
observations at the radio telescope - but if this was implemented it would
force the software problems to be fixed.


Jim Palfreyman


On 22 July 2016 at 06:01, Brooke Clarke <bro...@pacific.net> wrote:

> Hi Tom:
>
> I like this idea.  I addresses the lesson from Y2K that something done
> often works much better than something done only occasionally.
> That's way you see the firetruck at the local store, because it's used all
> the time and so is more likely to work when needed.
>
> --
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> The lesser of evils is still evil.
>
>  Original Message 
>
>> Hi Tom...
>>
>> Does your proposal allow for a Zero leap second, or does it require
>> either plus or minus 1 to work? Seems like you could stay closer to the
>> true value if you also have a zero option. Might also cause less
>> consternation for some services, like the finance and scientific worlds,
>> that seem to have critical issues when an LS appears.
>>
>> I like your point that by having it occur monthly it forces systems to
>> address issues promptly, and maybe that's the argument for the non-zero
>> option.
>>
>> Tom Holmes, N8ZM
>>
>>
>> -Original Message-
>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van
>> Baak
>> Sent: Thursday, July 21, 2016 1:28 PM
>> To: Discussion of precise time and frequency measurement <
>> time-nuts@febo.com>
>> Cc: Leap Second Discussion List <leaps...@leapsecond.com>
>> Subject: Re: [time-nuts] Leap second to be introduced at midnight UTC
>> December 31 this year
>>
>> Time to mention this again...
>>
>> If we adopted the LSEM (Leap Second Every Month) model then none of this
>> would be a problem. The idea is not to decide *if* there will be leap
>> second, but to force every month to have a leap second. The IERS decision
>> is then what the *sign* of the leap second should be this month.
>>
>> Note this would keep |DUT1| < 1 s as now. UT1 would stay in sync with
>> UTC, not so much by rare steps but by dithering. There would be no change
>> to UTC or timing infrastructure because the definition of UTC already
>> allows for positive or negative leap seconds in any given month.
>>
>> Every UTC-aware device would 1) know how to reliably insert or delete a
>> leap second, because bugs would be found by developers within a month or
>> two, not by end-users years or decades in the future, and 2) every
>> UTC-aware device would have an often tested direct or indirect path to IERS
>> to know what the sign of the leap second will be for the current month.
>>
>> The leap second would then become a normal part of UTC, a regular monthly
>> event, instead of a rare, newsworthy exception. None of the weird bugs we
>> continue to see year after year in leap second handling by NTP and OS's and
>> GPS receiver firmware would occur.
>>
>> Historical leap second tables would consist of little more than 12 bits
>> per year.
>>
>> Moreover, in the next decade or two or three, if we slide into an era
>> where average earth rotation slows from 86400.1 to 86400.0 to 86399.9
>> seconds a day, there will be zero impact if LSEM is already in place.
>>
>> /tvb
>>
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>> and follow the instructions there.
>>
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Re: [time-nuts] Visiting Greenwich

[Jim Harman]

Those in Australia might want to check out the traveling "ships, clocks,
and stars" exhibit at the Australian National Maritime Museum in Sydney
through Oct 30. I saw this earlier this year when it was in Mystic
Connecticut and found it very interesting. It is also appropriate for non
Time Nuts. It presents a good overview of the quest for longitude at sea
and features beautiful working replicas of Harrison's clocks.

On Wed, Jul 6, 2016, 7:46 PM Morris Odell <vilgo...@bigpond.net.au> wrote:

> This is a terrific thread. I have been to Greenwich too and also some of
> the
> clock exhibits in London. There's a beautiful pendulum master and slave
> clock set up in the British Museum, and there's an original huge Caesium
> (British spelling!)  frequency standard in the Kensington Science Museum.
> The last time I was there in 2013 there was also a special feature
> exhibition about Alan Turing and the Bletchley code breakers.  I did pass
> through Bletchley station on the train about 20 years ago when I was in the
> UK but regrettably didn't have the time to stop there. I can recommend the
> climb up the hill at Greenwich to anyone - it's definitely worth the
> effort.
> They didn't allow photography of the Harrison clocks but I did manage to
> sneak one or two before the minder got to me :-)
>
> I'd love to have a genuine electro-optical speaking clock. There's one in
> the Australian Telecom museum not far from where I live. There's also a
> terrific display of a complete electromechanical telephone exchange
> including a speaking clock in the telecommunications museum in Stockholm
> but
> as I don't speak Swedish I couldn't understand what it was saying.  I've
> just finished making a speaking clock using more modern technology, it uses
> a 30 year old speech synthesizer chip and sounds just like Stephen Hawking.
>
> Morris
> Melbourne, Australia
> -----
>Date: Wed, 6 Jul 2016 10:42:19 +1000
> From: Jim Palfreyman <jim77...@gmail.com>
> To: Discussion of precise time and frequency measurement
> <time-nuts@febo.com>
> Subject: Re: [time-nuts] Visiting Greenwich
>
> Speaking of "speaking clocks" - here's two photos of the ones that used to
> be used in Australia:
>
> https://en.wikipedia.org/wiki/Speaking_clock#Australia
>
> The top photo with rotating optical disks is a gorgeous piece of machinery.
>
> The one below - I have one, and I keep it running.
>
> :-)
>
>
>
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Re: [time-nuts] Visiting Greenwich

[Jim Palfreyman]

Speaking of "speaking clocks" - here's two photos of the ones that used to
be used in Australia:

https://en.wikipedia.org/wiki/Speaking_clock#Australia

The top photo with rotating optical disks is a gorgeous piece of machinery.

The one below - I have one, and I keep it running.

:-)


On 6 July 2016 at 09:30, Clint Jay  wrote:

> Actually,  you're absolutely right,  the speaking clock is on an upper
> gallery display with other timepieces, some of which are amazing.
>
> I've just looked back through my photo gallery and it's the Greenwich time
> service I'm thinking of, a large, five rack wide system that's got (from my
> obviously flaky memory) a Loran receiver and an atomic standard.
>
> Small pic attached.
> On 5 Jul 2016 23:28, "Alan Melia"  wrote:
>
> > Hi Clint I think when I discussed this last a few years ago with the
> > speaking clock designer and David Rooney the man responsible for the time
> > gallery at Greenwich. The clock is an early quartz unit, probably made at
> > the then Post Office Reseach Labs at Dollis Hill in NW London.  The clock
> > is quite a beast ! It was found in a skip (Dumpster) having been donated
> to
> > a university in the late 1940s, and was refurbished by a local enthusiast
> > for David. He did a good job because I believe he had no access to any
> > documents or circuits. I tried to find some information but it would seem
> > the archive has been lost (vandals !!) It probably contains strange
> things
> > like neon ring counters :-))
> >
> > Alan
> > G3NYK
> >
> > - Original Message - From: "Clint Jay" 
> > To: "Discussion of precise time and frequency measurement" <
> > time-nuts@febo.com>
> > Sent: Tuesday, July 05, 2016 9:13 PM
> > Subject: Re: [time-nuts] Visiting Greenwich
> >
> >
> > They also have TIM the speaking clock which has a rack mounted  atomic
> >> standard.
> >> On 5 Jul 2016 21:01, "John Dalziel - crashposition" <
> >> j...@crashposition.com>
> >> wrote:
> >>
> >> I would also recommend the Worshipful Company of Clockmakers collection
> at
> >>> the Science Museum. It’s a great collection and they have some of
> >>> Harrison's wooden long case clocks as well as his final chronometer,
> H5.
> >>>
> >>>
> >>>
> >>>
> http://www.sciencemuseum.org.uk/visitmuseum/plan_your_visit/exhibitions/clockmakers-museum
> >>>
> >>>
> >>> John Dalziel
> >>> computus.org
> >>>
> >>>
> >>> Message: 4
> >>> Date: Mon, 4 Jul 2016 18:31:35 -0400
> >>> From: Dave Martindale 
> >>> To: Discussion of precise time and frequency measurement
> >>> 
> >>> Subject: [time-nuts] Visiting Greenwich
> >>> Message-ID:
> >>> 
> >>> Content-Type: text/plain; charset=UTF-8
> >>>
> >>> I am in London England at the moment, playing tourist with the rest of
> my
> >>> family. I want one day to be a visit to the National Maritime Museum at
> >>> Greenwich, which includes the Royal Observatory Greenwich. I am
> >>> particularly interested in seeing Harrison's H1 through H4, plus other
> >>> high-precision mechanical timekeepers (pendulum clocks, etc).
> >>>
> >>> I know they are at the NMM - their web site shows some of them. But
> where
> >>> are they located on the site? The NMM has a large main building down
> near
> >>> the Thames, while the Royal Observatory and related buildings are on
> the
> >>> top of a hill further inland in Greenwich Park. Are the chronometers
> and
> >>> other precision timekeepers on display somewhere in the Royal
> >>> Observatory,
> >>> or down in the main NMM building? I've spent an hour or two browsing
> web
> >>> sites without finding this particular bit of information.
> >>>
> >>> I figure there must be list members who have visited the NMM, and know
> >>> where the precision timekeepers are actually displayed.
> >>>
> >>> Thanks,
> >>> Dave
> >>> ___
> >>> 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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> >> and follow the instructions there.
> >>
> >
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Re: [time-nuts] Visiting Greenwich

[Jim Palfreyman]

I was lucky. About ten years ago when visiting I turned up to the Greenwich
Observatory and walked around the corner to see the Harrison clocks.

I didn't know they were there. I didn't know they were anywhere.

I'd read the book, seen the doco, but for some reason assumed they weren't
around any more.

To get a surprise and see them *working* was a great moment in my life.

As David Gilmour once said, "I've never had the pleasure of hearing Dark
Side of the Moon for the first time", well I got the surprise of seeing the
working Harrison clocks - and not knowing it was coming.

Brilliant!


Jim Palfreyman


On 5 July 2016 at 15:00, Peter Monta <pmo...@gmail.com> wrote:

> Hi Dave,
>
> The Harrisons are indeed at the observatory; also look for a regulator
> pendulum clock in the octagon room.  I'm not quite sure whether it was
> running when I was there some years back.
>
> Could it hurt to petition the observatory's powers-that-be for a little hut
> or something at the ITRF meridian?  :-)
>
> If you do get to Bletchley Park, give the National Museum of Computing a
> look-see as well (it's just a short walk).  I believe both facilities have
> benefited from recent infusions of money and support, which is great.
>
> Cheers,
> Peter
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Re: [time-nuts] Maser 0.7 nsec jumps solved

[Jim Palfreyman]

Hold your horses folks.

There is more on this tale!

To recap we put the SSR on the aircon (at zero crossing) and the jumps got
very very worse. So we turned the aircon off again (winter here - so not
really needed) and the jumps dropped, but didn't go away. :-(

So we also have a heater in the room (simple 1200W column heater) and a
temperature monitor that turns the cooling or heating on as appropriate. So
we also replaced the heating relay with an SSR and it all now seems to have
gone away.

We are now thinking that the aircon AND heating *relays* had started to pit
after years of use and so give off radio transients which managed to get in
and interfere with the extremely low (-100 dBm) signal coming from the
physics package and going into the maser electronics.

We have now run for four days with no clock jumps with both aircon and
heater on and with 0V crossing SSR relays.

"Welcome to the jungle, we've got fun and games..."

Jim Palfreyman


On 3 June 2016 at 15:00, Jim Palfreyman <jim77...@gmail.com> wrote:

> Hi All,
>
> Thanks so much for your input and thoughts. It has really proved helpful
> here at the observatory.
>
> As it turned out we easily obtained a zero-crossing solid state relay so
> we thought we'd try it.
>
> And, drumroll..
>
>
>
> It made things so much terribly *worse* than ever before. (As predicted by
> many of you above.)
>
> We are going to try a SSR that switches at the peak - but we need to order
> one. So stay tuned on those results.
>
> There is of course the "move the bloody thing far away from the maser"
> solution which could end up being a serious option. These air conditioning
> units are small and cheap (window-type), so we are trying to find the
> cheapest solution - and if that ends up being some ducting - so be it!
>
>
> Jim Palfreyman
>
>
>
> On 26 May 2016 at 13:13, Andy <ai.egrps...@gmail.com> wrote:
>
>> On Wed, May 25, 2016 at 12:59 PM, Mike Monett <
>> timen...@binsamp.e4ward.com>
>> wrote:
>>
>> LTspice shows  switching  at 0V is the best point in  time.  ...
>>
>>
>>
>> Bzzzt!  Your simulation is seriously flawed, and your conclusions are
>> wrong.  What you forgot, or may not have realized, is that SPICE's initial
>> transient solution is obtained by having the signal sources already turned
>> on (at the moment of the Big Bang) and set to their initial value, so the
>> current through L2 is limited by DC conditions.  That is not anything
>> close
>> to switching the driving voltages on.  It is having one waveform sit at
>> +169.7V DC for a very long time ('forever'), and then letting it follow a
>> cosine wave.
>>
>> Re-run the simulation with "UIC" added to the .tran statement (.tran 50ms
>> uic) and see what it shows.  Using UIC forces the initial voltage to be 0V
>> at time=0, the start of the simulation.  That's like having the switch
>> initially open.
>>
>> Or if you don't like that, multiply the sources by a PWL waveform that
>> starts both voltages at 0V and then switches them on, a few milliseconds
>> into the simulation, with the appropriate phase.
>>
>> Or use an actual switch.  LTspice has a switch element you could use.
>>
>> I guarantee you, the case with the voltage switching on at the 0V point in
>> the voltage waveform, causes greater currents.
>>
>> The smaller surge current happens when the source is connected at the
>> moment when the current i(t) would be 0A if it were a continuous waveform.
>> For an inductive load, this happens when the voltage v(t) would be +/-
>> peak
>> (or near peak, for a real load which has both inductance and a little
>> resistance).  This condition also results in no surge, thus no L/R decay.
>>
>> All of this might not be relevant to a mechanical system, where surge
>> current is caused by rotational inertia, rather than anything electrical.
>>
>> Regards,
>> Andy
>> ___
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>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
>
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Re: [time-nuts] GPS altitude somewhat wrong?

[Jim Harman]

On Wed, Jun 8, 2016 at 4:33 PM, Van Horn, David <
david.vanh...@backcountryaccess.com> wrote:

> Backcountry Access, Inc.
> 2820 Wilderness Pl, Unit H
> Boulder, CO  80301 USA
>

Google Earth has the elevation of this address as 5272' which is a good
deal closer to your reading...


-- 

--Jim Harman
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Re: [time-nuts] Maser 0.7 nsec jumps solved

[Jim Palfreyman]

Hi All,

Thanks so much for your input and thoughts. It has really proved helpful
here at the observatory.

As it turned out we easily obtained a zero-crossing solid state relay so we
thought we'd try it.

And, drumroll..



It made things so much terribly *worse* than ever before. (As predicted by
many of you above.)

We are going to try a SSR that switches at the peak - but we need to order
one. So stay tuned on those results.

There is of course the "move the bloody thing far away from the maser"
solution which could end up being a serious option. These air conditioning
units are small and cheap (window-type), so we are trying to find the
cheapest solution - and if that ends up being some ducting - so be it!


Jim Palfreyman



On 26 May 2016 at 13:13, Andy <ai.egrps...@gmail.com> wrote:

> On Wed, May 25, 2016 at 12:59 PM, Mike Monett <timen...@binsamp.e4ward.com
> >
> wrote:
>
> LTspice shows  switching  at 0V is the best point in  time.  ...
>
>
>
> Bzzzt!  Your simulation is seriously flawed, and your conclusions are
> wrong.  What you forgot, or may not have realized, is that SPICE's initial
> transient solution is obtained by having the signal sources already turned
> on (at the moment of the Big Bang) and set to their initial value, so the
> current through L2 is limited by DC conditions.  That is not anything close
> to switching the driving voltages on.  It is having one waveform sit at
> +169.7V DC for a very long time ('forever'), and then letting it follow a
> cosine wave.
>
> Re-run the simulation with "UIC" added to the .tran statement (.tran 50ms
> uic) and see what it shows.  Using UIC forces the initial voltage to be 0V
> at time=0, the start of the simulation.  That's like having the switch
> initially open.
>
> Or if you don't like that, multiply the sources by a PWL waveform that
> starts both voltages at 0V and then switches them on, a few milliseconds
> into the simulation, with the appropriate phase.
>
> Or use an actual switch.  LTspice has a switch element you could use.
>
> I guarantee you, the case with the voltage switching on at the 0V point in
> the voltage waveform, causes greater currents.
>
> The smaller surge current happens when the source is connected at the
> moment when the current i(t) would be 0A if it were a continuous waveform.
> For an inductive load, this happens when the voltage v(t) would be +/- peak
> (or near peak, for a real load which has both inductance and a little
> resistance).  This condition also results in no surge, thus no L/R decay.
>
> All of this might not be relevant to a mechanical system, where surge
> current is caused by rotational inertia, rather than anything electrical.
>
> Regards,
> Andy
> ___
> time-nuts mailing list -- time-nuts@febo.com
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Re: [time-nuts] Maser 0.7 nsec jumps solved

[Jim Palfreyman]

As far as a remedy goes we are going to try a solid state relay that only
switches on at 0V in the AC waveform. This should slow the inrush current,
and hopefully the magnetic impulse.

If this doesn't work, then a better model of air conditioner might have to
be installed. These ones do come on with a big "thump".


Jim Palfreyman


On 22 May 2016 at 21:43, Magnus Danielson <mag...@rubidium.dyndns.org>
wrote:

> Jim,
>
> On 05/22/2016 03:58 AM, Jim Palfreyman wrote:
>
>> Hi all,
>>
>> Awhile back I posted about some mysterious 0.7 ns jumps in three different
>> masers (of the same brand) at three different locations around Australia.
>>
>> Well we think we've found the problem. All three locations also have
>> in-room air conditioners of the same brand. These are used for cooling
>> only. When these units turn on, we think they induce a magnetic field from
>> the inrush current that briefly disrupts the maser. We don't think it's
>> electrical because moving to another phase did not change things.
>>
>> These air conditioners are all quite close to the masers. Typically a
>> metre
>> or 2 away.
>>
>> Much was done to discover this, but the clincher was that when the weather
>> cooled enough at the southern most location (Hobart), we turned off the
>> air
>> con (only heating was needed) and the problem vanished.
>>
>> So there's a lesson here for all maser owners. The jump of 0.7 nsec is not
>> much, but it's huge for VLBI and for time-nuts.
>>
>
> Good that you have found the offender, but have you been able to remedy it
> by other means than turning the AC off?
> I think others H-maser owners would love to know, and potentially the
> vendor you have.
>
> Cheers,
> Magnus
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[time-nuts] Maser 0.7 nsec jumps solved

[Jim Palfreyman]

Hi all,

Awhile back I posted about some mysterious 0.7 ns jumps in three different
masers (of the same brand) at three different locations around Australia.

Well we think we've found the problem. All three locations also have
in-room air conditioners of the same brand. These are used for cooling
only. When these units turn on, we think they induce a magnetic field from
the inrush current that briefly disrupts the maser. We don't think it's
electrical because moving to another phase did not change things.

These air conditioners are all quite close to the masers. Typically a metre
or 2 away.

Much was done to discover this, but the clincher was that when the weather
cooled enough at the southern most location (Hobart), we turned off the air
con (only heating was needed) and the problem vanished.

So there's a lesson here for all maser owners. The jump of 0.7 nsec is not
much, but it's huge for VLBI and for time-nuts.


Jim Palfreyman
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Re: [time-nuts] Unix software to generate nice looking *DEV plots

[Jim Palfreyman]

R might be a good place to start.

I use it extensively for astrophysics (all graphs in my recent pulsar paper
accepted in The Astrophysical Journal were done using R:
http://arxiv.org/pdf/1602.01899v1.pdf).

R has a huge support network. I haven't even looked, but I bet it'd be a
great place to start.

And it's free.

As an aside, fellow time-nuts may be interested in the paper. It's mostly
about timing after all.


Jim Palfreyman


On 17 March 2016 at 21:29, Attila Kinali <att...@kinali.ch> wrote:

> Moin,
>
> I'm looking for some non-GUI software to generate the different *DEV
> plots we generally use to asses oscillators with. Timelab is nice,
> but if you are evaluating two dozen measurements using different
> parameters, it becomes very tedious to generate the plots. Not
> to talk about the problem that the plots are not really reproducable,
> which is a very important property, when publishing results.
>
> I could for sure write myself wrappers around
> gnuplot/ploticus/mathplotlib/..
> to generate the *DEV plots, but I'm not keen on reinventing the wheel.
>
> Thus I'd like to ask whether someone has any hints on what to use.
>
> 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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[time-nuts] Fwd: Home-brew GPSDO

[Jim Harman]

-- re-posting with smaller attachment --


On Thu, Mar 17, 2016 at 12:40 PM, Logan Cummings <logan.cummi...@gmail.com>
wrote:

>  I was planning on using the Due's ADC to measure the voltage on the
> integrator capacitor, but hadn't decided yet about a "good" current source
> vs. a series resistor on the output of an XOR or DFF phase comparator to
> put charge on the capacitor.
>
>  Hopefully someone else can chime in with some better links and circuit
> descriptions.
>

You might want to consider the approach used in the attached schematic and
write-up. This is for an Arduino Micro based system, but you should be able
to adapt it to work with the Due. The simple RC network works OK if you can
set the ADC full scale range to 2.5 V or less, but shows some nonlinearity
at the high end due to the exponential charging. I have been experimenting
with a circuit that uses a better current source, which I can pass along if
you are interested. So far the performance seems to be about the same as
this simple circuit.


-- 

--Jim Harman




-- 

--Jim Harman


Arduino GPSDO Schematic v4.pdf
Description: Adobe PDF document


Arduino GPSDO notes.docx
Description: MS-Word 2007 document
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Re: [time-nuts] Conditioning Rubidium Oscillators

[Jim Harman]

Attila and Bruce and Adrian,

You are right, I stand corrected. Despite the talk in the app note about
aging rates and calculating the average slope of the frequency offset, and
about how m represents the rate of change of the frequency offset, when you
dig into the formulas, they are doing a linear fit to determine the slope
of the phase, which of course corresponds to the frequency offset itself
and not its rate of change.

Sorry for any confusion I may have caused. Attila, good suggestion on the
Kalman filter. I will educate myself about that.


On Tue, Mar 15, 2016 at 8:30 PM, Bruce Griffiths <bruce.griffi...@xtra.co.nz
> wrote:

> They actually determine the phase offset and rate of change of phase (i..e.
> frequency offset and not frequency drift as claimed in the paper) from a
> linear
> regression fit to a sequence of phase differences.
> The results from the regression fit are then used in an adaptive PID loop.
>
> Bruce
>
>
> On Tuesday, March 15, 2016 10:28:39 PM Adrian Godwin wrote:
> > My understanding of the article was that although fairly simple control
> > techniques such as PID were used, their innovation was to determine what
> > function the loop was performing, (initial lock, stability, and
> transition
> > from one to the other) and to choose a set of constants for loop control
> > appropriate to each type. The ideal loop characteristics are not the same
> > for all of these.
> >
> > On Tue, Mar 15, 2016 at 7:51 PM, Attila Kinali <att...@kinali.ch> wrote:
> > > On Mon, 14 Mar 2016 19:56:42 -0400
> > > Jim Harman <j99har...@gmail.com> wrote:
> > >
> > >
> > > Disclaimer: Control theory is not my strongest topic. I am pretty sure
> > > that what I have written here is correct. But if anyone finds any
> > > mistakes, please correct me.
> > >
> > > > On Mon, Mar 14, 2016 at 2:37 PM, Lars Walenius <
> > >
> > > lars.walen...@hotmail.com>
> > >
> > > > wrote:
> > > > > I read this but couldn´t understand why this is superior to the
> > > > > PI-loop
> > > > > with a pre-filter?
> > >
> > >
> http://ptfinc.com/wp-content/uploads/2016/03/App_37_RubContol-Rubidium-Con
> > > trol-%E2%80%93-A-Different-Approach.pdf>
> > > > > Anybody can say why? Even if regression is very useful the
> limitation
> > >
> > > of
> > >
> > > > > the GPS and ionosphere will be the problem?How much better is it
> > >
> > > reasonable
> > >
> > > > > to get??
> > >
> > > A PID loop adapts to a step as input faster than a PI loop.
> > > To give a rule of thumb: the D part is used to predict how fast
> > > the error is moving. If the error is shrinking fast, there will
> > > be an overshoot once the error reaches zero. Thus the D part is
> > > used to make the rate of change slower once the error becomes small..
> > > Nothing more.
> > >
> > > The wikipedia entry on PID controllers explains these things in
> > > some detail and should help understand it.
> > >
> > > > I think the potential benefit of this approach is that it
> continuously
> > > > predicts the long term drift of the oscillator and attempts to
> > > > compensate
> > > > for it.
> > >
> > > Nope, the above appnote does not predict anything. It's not an adaptive
> > > control system at all. All they do is describe an PID controller
> without
> > > using the common language of the control theory people.
> > >
> > > > If the drift is reasonably linear, this means that you can use a
> > > > larger time constant in the control loop and thus be less sensitive
> to
> > > > short term GPS timing variations, while keeping the phase error
> close to
> > > > zero
> > >
> > > If the drift is linear, then the D part of the PID control loop will
> > > actually slightly increase the error compared to a PI controller.
> > >
> > > Proper adaptive control systems can also model higher order (ie changes
> > > that have components with a second or third (or higher) derivative) and
> > > the more fancy stuff even non-linear "drift".
> > >
> > > But the math behind that is not easy, and you need to have a good idea
> > > what the system (including reference, "plant", "sensor" and noise
> sources)
> > > looks like to build a control loop that improves on the PID controller.
> > > It's al

Re: [time-nuts] Home-brew GPSDO

[Jim Harman]

On Thu, Mar 17, 2016 at 4:38 PM, Nick Sayer via time-nuts <
time-nuts@febo.com> wrote:

> Anyway, my hat’s off to Jim - it’s an extremely elegant mechanism, and it
> was inexpensive both in parts and board space to add.


Thanks for the kudos Nick. The design is what I just posted on another
thread if you want to see the schematic. Credit for the design actually
goes to Lars Walenius, who posted it here a couple of years ago.


-- 

--Jim Harman
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Re: [time-nuts] Conditioning Rubidium Oscillators

[Jim Harman]

On Mon, Mar 14, 2016 at 2:37 PM, Lars Walenius <lars.walen...@hotmail.com>
wrote:

> I read this but couldn´t understand why this is superior to the PI-loop
> with a pre-filter?
>
>
> http://ptfinc.com/wp-content/uploads/2016/03/App_37_RubContol-Rubidium-Control-%E2%80%93-A-Different-Approach.pdf
>
> Anybody can say why? Even if regression is very useful the limitation of
> the GPS and ionosphere will be the problem?How much better is it reasonable
> to get??
>

I think the potential benefit of this approach is that it continuously
predicts the long term drift of the oscillator and attempts to compensate
for it. If the drift is reasonably linear, this means that you can use a
larger time constant in the control loop and thus be less sensitive to
short term GPS timing variations, while keeping the phase error close to
zero

Of course if the oscillator drift is not predictable, this won't help and
might even make things worse.

I have done some experiments with an OCXO and a controller design similar
to the one Lars posted some time ago. I plotted the trend in the 3-hour
average DAC values over many days and used Excel to do a least-squares fit
to that data. As long as the oscillator is powered on continuously, this
gives an R^2 of over 90%, so the linearity of the drift is very good. If I
use this slope as a correction factor, i.e. adding X DAC counts per day to
the output of the PI control algorithm, it significantly reduces the
average TIC error at long time constants


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--Jim Harman
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Re: [time-nuts] When does NIST change to DST?

[Jim Harman]

WWVB has sent the signal to switch to DST but the website has not changed
yet.

On Sun, Mar 13, 2016, 10:11 AM  wrote:

> I noticed that NIST, at http://nist.time.gov/ , is still sending standard
> time. When do they change?
>
> John  WA4WDL
>
>
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Re: [time-nuts] PRS 10 and serial port communication

[Jim Harman]

Actually a null modem is just the device that interchanges the connections,
Rx to Tx and sometimes DSR to DTR and others. The inverters are needed in
this case to convert zero or negative voltage levels to positive and vice
versa.

On Fri, Mar 4, 2016, 6:00 PM Artek Manuals  wrote:

> The "inverter's" went by the jargon name of "null modem" back in the day
> ...if you google "null modem" you will find the wiring diagrmas for
> rolling your own with a couple DB9 connectors I have to use the null
> modem adapter  when using a standard off the shelf serial cable with my
> z3801A as well
>
> Dave
>
>
>
>
> On 3/4/2016 2:26 PM, Philip Zahariev via time-nuts wrote:
> > As already tell you I have success with inverters and now can monitor
> state of PRS 10. Attached send current status for comments. Any help
> appreciated.
> > Best regardsPhilip
> >
> >
> >From: Hal Murray 
> >   To: Philip Zahariev ; Discussion of
> precise time and frequency measurement 
> > Cc: hmur...@megapathdsl.net
> >   Sent: Friday, 4 March 2016, 11:43
> >   Subject: Re: [time-nuts] PRS 10 and serial port communication
> >
> >
> >> As I already write PRS10 is configured as serial communication. With
> >> oscilloscope I can see serial signals, but when enter this signal in
> >> computer with TTL level USB2serial converter all information is
> repeatable
> >> character unknown for me and not as described in manual.
> >
> > You may need to add or remove an inverter in there.
> >
> > Most serial ports on microprocessors and USB to serial chips are
> expecting a
> > TTL to RS232 level shifter and the standard level shifter chips all have
> an
> > inverter.  If there are 0 or 2 inverters it should work.
> >
> > Some GPS modules don't have any level shifter.  Some devices include an
> > inverter but not the level shifter.  That doesn't meet specs but it
> generally
> > works if you connected it to a real serial port (with level shifter).
> >
> > I would connect a scope to the output side of the USB to serial chip and
> send
> > it occasional characters and use that as a reference for what a
> character is
> > supposed to look like.
> >
> > Then look to the input side and see if it looks similar.  In particular,
> > verify that the idle level is the same.  Then check the baud rate and
> parity.
> >
> >
> >
> >
> >
> > ___
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> >
>
>
> --
> Dave
> manu...@artekmanuals.com
> www.ArtekManuals.com
>
> ---
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Re: [time-nuts] PRS10 and missing serail port communication

[Jim Harman]

Make sure Rx on the converter is connected to Tx on the PRS10 , Tx to Rx,
and the polarity is correct. The transmit lines should be at 0 V when idle.
Not sure about the PRS10, but official RS-232 requires the idle (Mark)
voltage to be -3 or lower.

On Thu, Mar 3, 2016, 5:00 PM Philip Zahariev via time-nuts <
time-nuts@febo.com> wrote:

> I forgot to tell you, that during tests I use TTL (5V) level USB to serial
> converter.
>
> -Original Message-
> From: Mike Cook [mailto:michael.c...@sfr.fr]
> Sent: Wednesday, March 2, 2016 11:15 PM
> To: Philip Zahariev; Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] PRS10 and missing serail port communication
>
>
> > Le 2 mars 2016 à 15:50, Philip Zahariev via time-nuts <
> time-nuts@febo.com> a écrit :
> >
> > Hello group,
> >
> > Recently obtained from eBay PRS10 marked as no-lock. Of course my
> > first task was to open device and see what is current state of lamp,
> capacitor and etc.
> > surrounding parts. My surprise was that all things look pretty good
> > (of course is used). And frequency is not correct :-) Actualy first
> > 1-2 minutes frequency is pretty close to 10 MHz, but after all thing
> > is ready (hot) frequency go far away.
> >
> > My questions:
> >
> > 1. How bright should be the light from lamp? Few seconds after power
> > is applied to device lamp start shining, but I can see only if room
> > light is close to dark or if I use magnifying glass focused on hole for
> inspection.
> >
> > 2. I cannot communicate with PRS10 using RbMon10 (software from SRS).
> > Only obtain repeatable characters from PRS10 if start terminal program
> > with baud rate 9600 baud, 8 bits, no parity, with 1 start and 1 stop
> > bit and no answer of any command according manual. Double checked
> > according schematics and port is configured as serial. Any advice how to
> obtain communication?
>
>   RbMon10 will normally configure the PC serial port correctly. So it
> might be due to voltage levels? The PRS10 port is 0-5V TTL and not the
> usual +/-12V RS232 levels.
>  Also it requires XON/XOFF protocol. That would need to be configured for
> a Terminal prog connection.
>
>
> >
> > Best regards
> > Philip
> >
> > ___
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> > and follow the instructions there.
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Re: [time-nuts] Instrument BASIC

[Jim Sanford]

John:

I looked and found many implementations of TCL.
Which one is yours, and is there any documentation about using it to 
control instruments over HPIB?  Some of the links I looked at suggest it 
is a general purpose language.


BTW, I'm using an Ethernet to GPIB.  Love it!

Thanks & 73,
Jim
wb4...@amsat.org


On 2/27/2016 5:01 PM, John C. Westmoreland, P.E. wrote:

Magnus,

I used to be responsible for a couple of labs in the late 90's early 2000's
where we had several of these.

First - do you have this option installed:
Add Agilent Instrument BASIC 1C2  ?

We automated the VSA's using GPIB and TCL.  I jumped through some hoops to
make the TCL library
publicly available on SourceForge - and it is still there.  TCL is a basic
like language for easy instrument
control and worth looking at if you want this to be as easy as possible.

I noticed there are some nifty GPIB to USB adapters available now.

We ran 24/7 this way doing low noise analysis.

Best Regards,
John W.
AJ6BC


On Sat, Feb 27, 2016 at 8:06 AM, Magnus Danielson <
mag...@rubidium.dyndns.org> wrote:


Fellow time-nuts,

This is a little off the normal time-stuff, but I wonder if people just
happens to have some suitable input to give.

I have a couple of HP89410A/89441A and would like to see if it would be
nice to see what could be done using the instrument BASIC. How would I be
able to enable or install it?

Now, don't even bother to write comments about how you can do better using
software control from a PC with this and that tool, this is explicitly not
part of the question.

Cheers,
Magnus
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Re: [time-nuts] Next step up from basic GPS/PPS timekeeping

[Jim Harman]

On Thu, Feb 25, 2016 at 1:08 PM, Neil Green <nc...@hotmail.co.uk> wrote:

> I’ve decided to build this:
>
> http://www.hackersbench.com/Projects/1Hz/
>
> which has an easy to follow diagram. Parts have cost less than £5. I’m not
> expecting great things from it by any means, but it’s something I can get
> my head around and should improve my understanding (a little).
>

Good start!

Once you have built it and observed how sensitive it is to temperature
variations, you might want to take a look at this:

https://www.adafruit.com/products/3013

This breakout is based on the DS3231 chip, which is a temperature
compensated 32 KHz real time clock with a built in crystal and optional
battery backup.  It also has a 1 pps output.

It is reasonably stable and accurate out of the box, but if you want to
adjust it you can send it commands from a microprocessor that tweak its
frequency up and down in increments of about 0.1 ppm (about 3 seconds per
year). It does this by switching in and out tiny on-chip capacitors.


-- 

--Jim Harman
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Re: [time-nuts] Next step up from basic GPS/PPS timekeeping

[Jim Harman]

On Wed, Feb 24, 2016 at 2:53 PM, Nick Sayer via time-nuts <
time-nuts@febo.com> wrote:

> I can measure 1 ppb, but it takes 1000 seconds to do it ... My
> understanding is that better GPSDOs are able to provide for more granular
> phase detection.


It doesn't take a lot of hardware to get about 1000x better than that. The
Arduino-based design Lars Walenius posted a while ago can take a reading
every second with a resolution of about 1 nsec. It uses an HC390 divider to
reduce a 10 MHz OCXO to 1 MHz. The 1 MHz and pps pulse from the GPS feed an
HC4046 phase comparator, producing a 1 pps pulse 0-1 usec wide, with the
width proportional to the phase difference. This feeds one diode and an RC
network to make a ramp with its peak height (0 - 2.5V) proportional to the
phase difference. This feeds the processor's 10-bit A/D converter, which is
set for 2.5V full scale.The 1 pps signal triggers the A/D, capturing the
height of the pulse. One more resistor discharges the capacitor between
pulses. Because the discharge time constant is much longer than the
interrupt latency and A/D conversion time, the A/D captures the peak value.

I have been experimenting with this design for some time, with a lot of
learning along the way. Of course there are always potential improvements,
but the current design works surprisingly well. If someone can provide
access to a good set of test gear (I am in CT), I could better quantify the
performance.

My latest schematic is attached.


-- 

--Jim Harman


Arduino GPSDO Schematic v4.pdf
Description: Adobe PDF document
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Re: [time-nuts] Newbie questions

[Jim Harman]

On Tue, Jan 26, 2016 at 7:04 PM, <time...@metachaos.net> wrote:

> I am trying to learn more about electronics and start doing
> hardware projects. I have never been into model building or anything
> similar,
> so my construction skills are lacking. I understand a lot of things in
> theory,
> but practice still eludes me.
>

To get a better background in electronics, I would highly recommend "The
Art of Electronics" by Horowitz and Hill. The long awaited and fully
updated 3rd edition came out just last year and it is well worth the $80.00
price. As a person who has worked with electronics on and off since 1960, I
can say it teaches electronics the way I wish I had been taught. It has a
strong emphasis on practical applications and assumes only high school math.

Some here may pooh-poo it, but to get started building useful electronic
systems I would recommend the Arduino platform. Fully assembled processor
boards are about $25.00 from reputable suppliers and have plenty of I/O
pins to get you started. On some versions of the processor you can expand
the I/O by adding "shields" which mate to headers on the processor board.

All you need to do to is to plug the board into a USB port on your PC or
Mac and download the free IDE. Both the hardware and software are open
source so you can see exactly how they work under the covers if you want. A
wide variety of libraries is also available (all free) and there is a
lively user community. The programming language is a stripped-down version
of C++ with a bunch of simple extensions to support analog and digital
I/O.  Once your code is working you can either continue to power the system
through the USB port or run it stand-alone with a 9V battery or wall wart.

I have built a GPSDO based on the design posted here by Lars Walenius a
couple of years ago. It uses the Arduino Micro processor, which is nice
because it has a second serial port. This lets it get serial data from the
GPS and talk to the PC at the same time. I would be happy to post the
schematics and code if you are interested.

-- 

--Jim Harman
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Re: [time-nuts] Newbie questions

[Jim Harman]

I am a relative newbie here myself, but at the risk of starting a
firestorm, I would take issue with some of what Bob says below. See
comments interspersed.


On Wed, Jan 27, 2016 at 7:43 AM, Bob Camp <kb...@n1k.org> wrote:

> Hi
>
> Ok, so let me answer the questions you *should* have asked:
>
> (They are in no particular order. Number 3 probably should come first)
>
> 1) Is the gear I have enough to do this project?
>
> No, you will need some sort of frequency  / time standard. An atomic
> clock of some sort is pretty much a minimum. You probably also need
> a working GPSDO (or set of them) for comparison as well. You will also
> need a working / modern precision counter that will give you data down
> in the < 100 ps range.
>

This depends on your answer to #3 below. For my GPSDO, project, all I have
is a scope, DMM, and PC. I can't measure ADEV, but by setting the time
constant of my filter to 1000 sec and monitoring the TIC output I can be
pretty certain that my local reference is well within 100 nsec of the
"true" time.

>
> 2) How will this ultimately be built?
>
> At the very least, you will be building this with surface mount devices.
> If it’s a scratch build, you will be dealing with fine pitch parts. That
> gets
> you into a whole bunch of gear. It also gets you into a very real “is this
> fun or not” sort of question.
>

For my GPSDO I started with and Arduino board and a solderless breadboard.
Anything with an SMD is on a purchased breakout board that spreads its pins
to 0.1" centers. You do have to be careful to keep the wires short when
working with fast rise times. I migrated this to a solder-type breadboard
that mimics the layout of the solderless board and it is working fine.

>
> 3) What *is* the goal?
>
> "I’m going to make dinner” is the start of a process. It’s not enough of a
> goal to accomplish the task. Starting the task with a general objective is
> fine.
> It does need to be refined a bit before you go much further.
>

Agreed.

>
> Is this what most of us would call a GPSDO (self contained box) or is it
> something with a PC in the middle of it?
>

Mine runs either stand-alone or with a PC to monitor it.

>
> Is this an OCXO based “precision” device or is it something more simple?
>

I used a $25.00 surplus OCXO. Eventually I may invest in something better
but then I would have to get a timing GPS to go with it. Currently I am
using the $40.00 Adafruit module.

>
> Is a pure software solution good enough?
>

Mine is almost all software, but it has a TIC that consists of a 74HC4046
phase detector chip, a diode, a cap, and 2 resistors, feeding an A/D input
of the Arduino processor board. This gives a resolution of 1 ns.

>
> Each of those decisions (and that’s by no means a full list) will send you
> off
> in a very different direction.
>
For sure!

>
> 4) How long is this likely to take?
>
> Best guess based on the others who have done the same thing - several
> years.
>

I have been at it on and off for about two years but I have learned a lot
along the way.

>
> 5) How much is this likely to cost?
>
> If done the way others have done it, several thousand dollars up to
> quite a bit more than that.
>

My total investment (not including the scope, DMM, and laptop PC) is under
$200.

>
> 6) How much research is involved?
>
> Quite a bit. The information you need is scattered all over the place.
> Figure
> that you likely will read at least several hundred papers. There is a whole
> statistical language that is unique to these gizmos. This is *not* a
> follow a
> set recipe sort of project.
>

Again, depends on your answer to #3. I started with a working design and
code and modified it to suit my fancy. I am pleased with the result. It
keeps the brain cells firing.

>
> Lots of fun !!!
>

Absolutely!!


-- 

--Jim Harman
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Re: [time-nuts] Newbie questions

[Jim Harman]

t; receiver is probably more complex than can be easily handled by an
>> amateur so
>> I am most likely restricted by available receivers.
>>
>> I have also read, more than once, statements in this forum that something
>> or
>> another could be had for some low, low price so why build it yourself? I
>> think
>> that there are several reasons, including but not limited to the
>> following.
>>
>>   1. It is an interesting project.
>>
>>   2. It is an educational project.
>>
>>   3. You may have some ideas about how things could be done differently or
>>  better.
>>
>>   4. You may want some combination of features that is not commercially
>>  available or perhaps is not affordable even with a generous budget.
>>
>>   5. Many people on limited budgets are not limited by total cost, but
>> rather
>>  by incremental cost. So, someone may not be able to afford several
>> hundred
>>  dollars for a pre-built system. But, they may be able to afford $50
>> here
>>  and there. So, building it themselves is the only practical option.
>>
>>
>> Mike
>>
>>
>>
>>
>>
>>
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>
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-- 

--Jim Harman
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Re: [time-nuts] HP5370B & HP5345B Front-End IC Redesign Effort

[Jim Palfreyman]

Hi Mathew,

As someone who just lost their stop channel, I'm extremely interested in
this project!

Jim Palfreyman


On 23 January 2016 at 09:14, Mathew Breton <ab...@outlook.com> wrote:

> I was gifted an HP 5370B with the usual problem: front-end problems,
> probably due to overstress. It is currently up and running again with a set
> of 5345A series A3/A4 boards as I wasn't able to get a cheap pair of
> 5088-706x hybrid ICs.
> This sounds like a common problem. As a result, I'm designing an
> open-source drop-in (hopefully) replacement. My hat is off to the original
> IC designer, as it is not a trivial effort due to the wide input signal
> common-mode range, and very tight trigger timing requirements. Other items
> (like the E-ECL) output) are also adding a bit of extra effort.
> I'm hoping that someone(s) might be interested in working with me on it. I
> would like to have my assumptions and math checked before I start the
> detailed design phase, and perhaps contribute some better ideas.
> In addition, it would be really helpful if someone could run a few
> rise-time dispersion tests on an instrument with a working "B"-series A3/A4
> PCB set (my unit obviously doesn't qualify).
> Regards,
> Mat Breton
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Re: [time-nuts] Lady Heather Server On Raspberry Pi 2 Model B?

[jim s]

On 1/9/2016 6:36 AM, Chuck Harris wrote:

Unfortunately, LH uses a graphics toolkit that was written by
John Miles, and it, and he, is windows only.

I got started on converting it to PyQT4, but got side tracked.

Maybe this year is the year I get all of the stuff I have promised
done?

-Chuck Harris

Ed Armstrong wrote:
Has anyone successfully ran Lady Heather Server On Raspberry Pi 2 
Model B? As it's
not an x86 architecture processor, I assume Wine is no use and a 
custom compile is
needed. Am I correct? Can any of you suggest where I can learn to do 
that, I'm rather

new to Linux.

Thanks
Ed
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Depending on the executable, wine runs on ARM.  YMMV.

http://wiki.winehq.org/ARM

Qemu and Dosbox run quite a lot of things I have on Raspberry Pi, and 
other ARM SOC's that I have.


Thanks
Jim
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Re: [time-nuts] 5370B stop trigger not working

[Jim Palfreyman]

Thanks Chris.

I'm beginning to think my 5370B is heading towards a boat anchor.

We (as in all time-nut owners of 5370s) seriously need to research a
replacement part/circuit for the 7061/7062 parts.


Jim


On 22 December 2015 at 07:44, Christopher E. Brown <cbr...@woods.net> wrote:

>
> You might want to re-scope the start and stop channel outputs where they
> cross A4 and
> verify against the front panel labels.
>
> The signal line crossing A4 that lines up with frontpanel start is start
> and the one that
> lines up with stop is stop.
>
>
> I mention this because the A3 board is a carry over from another unit and
> the start/stop
> labeling on the board itself is reversed from the 5370B front panel labels
> and the parts
> list follows the board labeling.  So, if you read front panel and lookup
> P/N in list you
> get the wrong one.
>
>
> The safe thing is to follow back from the output crossing A4 that is
> failing and
> physically pull the hybrid and read the P/N on the mounting frame.  It
> should be a metal
> can in a screw together frame, the part is socketed.
>
>
> Once the A3 is out, do not remove the screws in frame, they just clamp the
> frame to part.
>  Whole thing is held in by the collar on the pot shaft.
>
>
> For a 5370B
>
> 5088-7061 (start channel hybrid)
> 5088-7062 (stop channel hybrid)
>
> the manual lists it reversed, and they are actually different parts (not
> just diff
> mounting frames) with crossed up triggers.
>
>
> 7061 (actual start manual lists as stop) is the one that usually fails and
> is almost
> impossible to find.  Took me several years (and the help of another nut
> with a parts unit)
> to get a working one.  7062 is much easier to find.
>
>
> On 12/13/2015 11:26 AM, Jim Palfreyman wrote:
> > Oops yes! I looked up the wrong item. I meant A3U1 which is 5088-7061
> >
> > Jim
> >
> >
> > On Sunday, 13 December 2015, Cok <electron...@jpkoning.nl> wrote:
> >
> >> According to the partlist A4U1 and A4U2 seems to be TL072CP opamps.
> >>
> >>>
> >>> jim77...@gmail.com said:
> >>>
> >>>> I have gone through the troubleshooting process from the manual and it
> >>>> seems
> >>>> to point to A4U2 (Schmidt trigger) being faulty.
> >>>>
> >>> I'd put a scope on it to check.
> >>>
> >>> Before I dive into this, does anyone have any advice? Most important
> being
> >>>> the Schmidt trigger - where do I get one?
> >>>>
> >>> You need more info - the manufacturer's part number or something like
> >>> that.
> >>>
> >>>
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Re: [time-nuts] Timestamps in audio files?

[Jim Lux]

On 12/21/15 3:19 AM, Tim Shoppa wrote:

As an adjunct to the thread about timestamped samples of LORAN
transmissions...

Are there any standard consumer-type audio file formats, that support
absolute time time/datestamps? Would not have to be done continuously, but
something like a time and date stamp inserted nearest each sample on a
second boundary.

I have worked with some analog tape audio formats in the past where
IRIG-type timestamps were written on a separate channel or on a subcarrier.

I know of many proprietary digital recording applications that make WAV's
or MP3's or proprietary codec formats, where the filename includes a
timestamp. Much more interested in standard formats where the timestamp is
embedded in the file itself.



For RF recordings, VITA49 has a standard for timestamps in the packet 
headers (4 flavors of epoch, multiple flavors of time format and precision)


Video file formats seem to draw from older time code things like SMPTE 
and are "relative" (so you're always fooling around trying to figure out 
the offsets).  I spent a few days earlier this year trying to put 
absolute time subtitles on video files using all manner of tools, and it 
was frustrating (ffmpeg, vlc, etc.. all were to no avail).  Trying to 
put UTC time into embedded timecode was also pretty unproductive (most 
tools don't like to see the first frame occurring at a time very 
different from 00:00:00:00)



In fact, in the music file world (e.g. MIDI) you see references to 
absolute and relative time, and there, they are really talking about 
time measured in seconds vs time measured in beats; e.g. whether the 
duration of something  is 1 second, or 2 quarter notes, which might be 
the same if the tempo is 120bpm.



You might look for solutions for people trying to synchronize multiple 
multimedia streams delivered over the internet (e.g. slides and 
accompanying narration or music) because they actually have a need for 
"show this slide at time HH:MM:SS and play this sound at HH:MM:SS" kind 
of synchronization.


I suspect, though, that this kind of info gets encapsulated in the 
transport layer, rather than the underlying files holding the info.




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Re: [time-nuts] timestamps on downconverted data streams

[Jim Lux]

On 12/20/15 12:17 PM, Bill Byrom wrote:

Yes, you can do that. My employer (Tektronix) makes RF Signal Analyzers
which sample at a high rate then use a DDC (Digital DownConverter based
on decimation and digital filtering) to produce a much smaller output
I/Q file at a smaller bandwidth and lower time resolution. The
decimation and digital filtering delay acquired signals, so you have to
correct for the group delay in these operations.
-


and, how do they do that correction? Or, do they leave up to you to do it?


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