Re: [time-nuts] Seeking Toyocom or NDK through hole oscillator information

[Tim Shoppa]

Quoting Wikipedia; 16.368 MHz is 16 times the 1.023 MHz C/A GPS signal chipping 
rate; multiplied by 96.25 to get the 1575.42 MHz L1 frequency and multiplied by 
75 to get the 1227.60 MHz L2 frequency.

> On Jun 14, 2018, at 1:53 AM, skipp isaham via time-nuts  
> wrote:
> 
> Seeking Toyocom or NDK through hole oscillator information
> 
> 
> Hello again to the group,
> 
> I'm looking for a Data Sheet or information that would provide
> the connection information for a (Epson) Toyocom TCO-519 or NDK
> PIA3003A Oscillator module, both are through hole mounting.
> 
> Both appear to be a reasonably conventional, but now a discontinued
> through-hole part, but I'm unable to find any same or similar data
> sheet information that would tell me how to use connect them. Both
> are 16.368 MHz
> 
> Appearance wise, they are both an approx 1 inch square, 3/8" high,
> silver metal covered oscillator module. Five through hole mounting
> connection leads on the bottom, one in each corner, the fifth lead
> is centered along the side between two corners.
> 
> A data sheet or even just the generic connection information with
> an idea of what each pin does would be wonderful. A few of these
> arrived in a parts donation box hand labeled "Trimble Development".
> 
> Possibly something Trimble significant with the 16.368 MHz
> frequency that I'm not yet aware of... if anyone would care
> to speculate, please do.
> 
> 
> Thank you in advance for your replies
> 
> cheers,
> skipp
> 
> direct Email skipp...@yahoo.com
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Re: [time-nuts] 5950 Crystal impedance meter manual

[Tim Shoppa]

I don't know how to use that particular Boonton unit. BUT...

This is a different (more automated) unit which came maybe 10 years later.
The guy does a good job showing how it works and uses it on real crystals:
https://www.youtube.com/watch?v=y-rCgumTn4Q=youtu.be=4m37s

Experimental Methods in RF Design shows how to a couple different simple
benchtop jigs to measure crystal motional parameters and compute Q.

Tim N3QE

On Wed, May 23, 2018 at 4:44 AM, tim...@timeok.it  wrote:

>
>Hi all,
>I found this Crystal Impedande Meter produced by RFL Industries inc,
> Boonton.
>I would like to understand how to use it and I do not have any
> documentation.
>I'm not even able to figure out if it works properly.
>I would like to ask you if someone owns the service/operating manual
> and can share it with me.
>Look at the picture thanks
>Luciano
>
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Re: [time-nuts] 4046 replacement

[Tim Shoppa]

There is no dead time issue at all with 4046 PLL's using the built-in XOR
(Type I) phase detector.

There can be a dead-time issue with 4046 PLL's using the built-in type II
(flip-flop) edge detector.

The 74HCT9046A uses current sources instead of voltage sources in its type
II (flip-flop) edge detector to avoid dead-time issues with this phase
detector.

The Type I phase detector was most commonly used in most 4046 narrowband
PLL applications.

The Type II was mostly used for the applications where the VCO had to track
over most of an octave or more than an octave. Most of these Type II
applications were relatively insensitive to dead time. (Otherwise the
phase-nuts 40 years ago would've noticed. Yes you can hear phase noise even
if they didn't have a good systematic way to measure it back then.)

If your original 4046 circuit has been working fine for the past 40 years
(the 4046 must be 40+ years old now) I see no reason to rip it out and
replace it with the newer variant. You may have trouble finding
through-hole (non-surface mount) 74HCT9046A's at this date anyway.

Tim N3QE

On Wed, Apr 18, 2018 at 5:40 AM, donald collie 
wrote:

> Thankyou Attila. I remember reading a book on PLL theory, recently,writen
> by a very knowledgable fellow, but I didn`t think to make a copy of his
> critique of the 4046. I recall that the nub of it was that the 4046 isn`t
> suitable for some applications because of a design flaw. Perhaps somebody
> in this group could explain further.
> Thankyou Bill, for the datasheet on the 74HCT9046, and your comments
> Cheers!.
> .Don
> jnr ZL4GX
>
>  utm_source=link_campaign=sig-email_content=webmail>
> Virus-free.
> www.avg.com
>  utm_source=link_campaign=sig-email_content=webmail>
> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>
> On Wed, Apr 18, 2018 at 8:28 PM, wb6bnq  wrote:
>
> > Hi Donald,
> >
> > You could consider the NXP 74HCT9046A as a replacement.  It is an
> improved
> > version of 4046.  However, you do need to study the spec sheet as it is a
> > bit different, but in a good way.
> >
> > I have included an attached PDF of the spec sheet, if it makes through
> the
> > mail list server.
> >
> > BillWB6BNQ
> >
> >
> > donald collie wrote:
> >
> > I have 4  frequency synthesiser projects, each using HEF4046BCN`s, but
> have
> >> recently read that this CMOS IC has a design flaw. What would be a
> better
> >> chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
> >> doesn`t have the same bug], or a 74HC7046AN - which is similar. Both
> these
> >> chips are more-or-less pin compatable TIA for any
> >> advice!.
> >> ..Don
> >>
> >>  >> source=link_campaign=sig-email_content=webmail>
> >> Virus-free.
> >> www.avg.com
> >>  >> source=link_campaign=sig-email_content=webmail>
> >> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
> >> ___
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> >>
> >>
> >>
> >
> >
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Re: [time-nuts] Dual GPSDO - any advantage?

[Tim Shoppa]

Most of the Chinese cheapo units have been frequency, not phase locked.

It would be great if you could put the GPSDO outputs into a 2 Channel scope and 
eyeball them for a while to see if they appear in phase (say plus-minus 20ns) 
over a few hours.

Tim N3QE

> On Apr 10, 2018, at 1:43 AM, donald collie  wrote:
> 
> I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
> error!] They are stated as being new, and use a Trimball dual oven OCXO. I
> plan to run these in parallel [2 antennas, 2 feedlines, and 2 GPSDO`s] It`s
> been said that a man with two watches is never happy - unless, of course,
> they agree with each other ;-). Being identical the outputs should be
> coherent, unless one becomes faulty [one advantage of having two - any
> discrepancy and you know something must be wrong]], but is there some
> crafty way I can squeeze a little more "accuracy" out of two than if I only
> used one?
> TIA for your commentsDonald
> Brett Collie ZL4GX
> 
> PS : I have no connection to the eBay seller. The US$9-50 seems to include
> a basic puck antenna, long downlead, and 4 interseries adaptors
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Re: [time-nuts] Weird Stuff WareHouse shutting down

[Tim Shoppa]

C was SUPERB for test equipment in the 1990's when the aviation industry
in Southern California was downsizing.

IMHO not nearly so interesting today. Unless you're into pneumatics in
which case they are a delight.

Tim N3QE

On Sun, Apr 8, 2018 at 10:36 AM, paul swed  wrote:

> Thanks
> It has to have been Apex that I visited. The back areas were a mix of open
> sky and sort of sheds.
> The air was typically pretty dry so the stuff held up well. There were
> things I would have liked to have grabbed.
> Could easily see a day digging around.
> Inside its stacked to the 20 ft ceilings and they have ladders like you see
> in home depot to get to the top.
> There was a genrad admittance bridge on the top shelf. In good condition
> and in the nice wood box.
> I did not go to C as I simply ran out of time. Pretty good?
> Regards
> Paul
> WB8TSL
>
> On Sun, Apr 8, 2018 at 12:18 AM, Jeff Woolsey  wrote:
>
> > Geez.  The Agilent IEEE-1588 units I mentioned a month or two ago were
> > the last things I bought there.
> >
> >
> > > There is one crazy place down in northern LA. Some what hard to get to
> > but
> > > my god the stuff. Overwhelming. They dicker also. Nothing like a tough
> > > bargain was there 3 years ago.
> >
> > I happen to have returned from a family spring break in LA/SD just
> > today.  Yesterday I visted C surplus in Duarte and picked up a couple
> > items, one was way-underpriced.  This morning I was at APEX Electronics
> > in Sun Valley.  Overwhelming is right.  Being where they are in LA they
> > have a fair amount of prop business.   Imagine the backroom at
> > WeirdStuff. Now imagine ther same thing, only open to the sky, out
> > back.  I inquired about a couple items near the front, but didn't have
> > room in the car (or my wallet) for them.  The Yelp reviews are accurate.
> >
> > --
> > Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
> > Nature abhors straight antennas, clean lenses, and empty storage
> > "Delete! Delete! OK!" -Dr. Bronner on disk space management
> > Card-sorting, Joel.  -Crow on solitaire
> >
> > ___
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[time-nuts] Timestamping audio waveforms

[Tim Shoppa]

I would like sub-millisecond timestamps for a mono audio radio signal that
I have in the shack.

The timestamps could be continuous (Every sample) or just every "frame"
where maybe a frame is a second to a minute.

I would like to calibrate both the absolute time as well as the delta time
between samples based on the timestamps. (I would expect that say a nominal
48kHz sample rate would be off by many tens of ppm because of crystal
tolerances.).

I have a both Windows and Linux based PCs running Audacity with a local
GPS-based LAN refclock and ntpd. I trust the ntpd time to be stable to the
sub-millisecond.

Can Audacity do this kind of timestamping for me based on the system clock?

Or should I, say, take the PPS from a GPS, and feed it into channel 2, with
the audio going into channel 1, and make a stereo recording? I suppose I
could then manually label the filename with the second the recording was
begun. There would likely be some delta (maybe half the sample interval?)
between the two channels but I'm fine with that as long as it is at the
sub-millisecond level.

Tim N3QE
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Re: [time-nuts] WWV/CHU

[Tim Shoppa]

It does not take a fancy receiver to hear WWV or CHU. Any super low end 
shortwave portable (less than $100) will do fine.

You then feed the audio into a PC with naps configured for NTP audio refclock.

The wideband USB connected DSP receivers are neat and I am using one for 
various purposes in the shack but not yet WWV. You would have to characterize 
one and it’s computer based DSP processing for latency.

Any such setup has to be characterized for latency (propagation + receiver+ 
soundcard) anyway. Sub-millisecond accuracy is a reasonable goal.

In continental US, one or more of the three 5/10/15 MHz WWV signals is 
receivable most any time of day. NTP WWV software knows how to cycle one 
particular model of receiver through the frequencies and can easily be modified 
to work with other computer-controllable receivers.

WWVH can be reliably heard for some of each day as well.

A recent QST or QEX had a nice simple 10MHz WWV receiver in it. I think it was 
oriented towards extracting 10MHz carrier and not for demodulating the time 
code, however.

Tim N3QE

> On Mar 29, 2018, at 6:12 AM, Hal Murray  wrote:
> 
> 
> What do I need in in order to get time from WWV or CHU?
> 
> Do I need a fancy receiver as a front end?  Do I have a chance with one of 
> the low cost USB thumb drive size receivers?
> 
> Is there an obvious software package to start with?  (Linux)
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Need a Watch Recommendation

[Tim Shoppa]

Dana, the magnetic impulse of a quartz watch stepping the second hand forward 
is easily picked up by an unshielded coil. Wind a couple hundred turns of 
magnet wire around a bottle cap and hold near the watch face. Plug into the 
microphone input of a PC and run audacity to record the waveform. You will see 
60Hz/120Hz buzz in the background but the second hand stepping impulses will 
clearly show as a sharp impulse every second. Of course a small electret 
microphone can pick up the sonic impulse too and will also be useful for purely 
mechanical watches.

Broadly I’ve found cheapie quartz watches to be way more accurate than a minute 
a month. In the past I’ve marveled here about my cars clock which drifts less 
than a minute every 6 months (DST change reset interval) despite being in a 
very adverse temperature range.

Tim N3QE

> On Mar 15, 2018, at 11:51 AM, Dana Whitlow  wrote:
> 
> Most of the quartz watches I've owned were off by about 1-2 minutes per
> month,
> which I consider inexcusable.
> 
> Agreed, the mechanical trimmer is rather problematical, but I'd sure like
> to see
> *something *that the sophisticated user can tweak at home. Measurement of
> the
> current rate error is probably not much of a problem; I once tried seeing
> the
> 32kHz signal in the watch by capacitive coupling to the face, and could
> detect
> the signal.  I just tried a token attempt on my current watch and failed,
> but it
> was a crude, unshielded attempt by merely laying a 'scope probe against the
> watch face.  I was being severely jammed by the local 1230 kHz AM station.
> Anyway, the idea is to observe the signal's phase drift while triggering
> the 'scope
> from a trusted 1PPS source.
> 
> So now all that's needed is an alternate way for trimming the watch's
> frequency
> without opening the case.  There must be a way...
> 
> Dana
> 
> 
>> On Thu, Mar 15, 2018 at 8:13 AM, Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> 
>>> On Mar 15, 2018, at 1:33 AM, Dana Whitlow  wrote:
>>> 
>>> I concur with Bill.  And even if one keeps tabs on the current watch
>> error,
>>> as is the usual practice by celestial navigators, once that error reaches
>>> or exceeds more than a minute the process frankly gets more clumsy and
>>> error prone.  And if a watch drifts in time very rapidly, one loses faith
>>> in its
>>> ability to coast at a known rate between checks against WWV, which
>>> opportunities are not always available when one wants, due to
>>> propagation issues.
>>> 
>>> Whatever happened to the quartz watches with trimmer capacitors
>>> for setting the rate?
>> 
>> Trimmer caps to set watch crystals are problematic. They are a source of
>> error
>> as well as a set mechanism. You bump this or that and the trimmer moves.
>> They
>> also cost money to buy and install properly (no flux in-between the plates
>> …).
>> Once that is all done you need a way to set them in the factory. Back in
>> the day,
>> yes, we hat line workers who did that sort of thing. We also sold the
>> crystal in the
>> watch module (not the whole module) for $2 once upon a time.
>> 
>> How close do you want to set it? In our case, the set was supposed to be <
>> 0.5
>> ppm of the target. Ideally you needed a design that would do a small
>> fraction
>> of a ppm in a typical situation.
>> 
>> If the trimmer is a normal device, you get about 120 degrees of travel for
>> the
>> useful part of the tuning curve. A tune range of 30 ppm for the crystal
>> and another
>> 20 ppm for the other parts would not be unusual. Even taking the 0.5 ppm
>> number,
>> you are into 120 / 100 = 1.2 degrees sort of set on that little trimmer.
>> 
>> Bottom line: They went away because they weren’t good enough and they were
>> to expensive …. Setting a modern “shoot the chip” register based module is
>> way
>> more accurate and reliable. It’s silicon so the cost is whatever sand is
>> selling
>> for ….
>> 
>> Bob
>> 
>>> 
>>> And radio controlled?  No way!
>>> The process is to delicate and marginal to rely upon.  Give me a
>>> good stable free-running watch any day.
>>> 
>>> I don't like the solar watch concept mainly because one sometimes
>>> has to go for weeks without an opportunity to expose his watch to
>>> direct sunlight (or some indoor equivalent) for the requisite period
>>> of several hours.
>>> 
>>> Yesterday I was reading the manual for the Citizen ECO series,
>>> and that thing requires far too much effort and complication to keep
>>> it working and on time.  A good watch must simply work, with no
>>> maintenance beyond occasional battery replacements (and possible
>>> gland replacement at battery-change time), and accurately enough
>>> that the time need never be reset between battery replacements.
>>> 
>>> I use an old quartz diving watch I bought just under 10 years ago,
>>> (brand no longer distinguishable), which has never drifted more than
>>> about 30 sec (usually less) between battery replacements, and 

Re: [time-nuts] Frequency deviations in Europe affect clocks

[Tim Shoppa]

If the drift had been 5 or 15 seconds over a few days, sure, "catching up"
is right.

But after two months of accumulated 7 minutes deviation, surely everyone
has already manually adjusted their clocks? And in the process of the grid
"catching up" won't everyones clocks now be 7 minutes fast after the
catch-up?

Tim N3QE

On Thu, Mar 8, 2018 at 9:50 AM,  wrote:

>
> Hi,
>
> from new years eve until today 00:00 the European Electricity Grid entsoe
> lost 16891 sinewaves, nearly 338 seconds. Enclosed you find the sketch of
> the development. From March 2 they are going to catch up again, it seems.
>
> I do a record of the grid frequency. My timebase is a TCXO, 0.4ppm off. I
> get a frequency value for any single sinewave, precision is 1.4*10^-4 Hz.
>
> Cheers
> Detlef Schücker
> DD4WV
>
> (See attached file: lostseconds.pdf)
>
> "time-nuts"  schrieb am 08.03.2018 02:16:55:
>
> > Von: Gerhard Hoffmann 
> > An: time-nuts@febo.com
> > Datum: 08.03.2018 02:41
> > Betreff: Re: [time-nuts] Frequency deviations in Europe affect clocks
> > Gesendet von: "time-nuts" 
> >
> >
> >
> > Am 07.03.2018 um 22:09 schrieb Poul-Henning Kamp:
> > >
> > >> This explains why my oven clock and the time/temperature display
> > >> on the building outside my apartment in Switzerland are six minutes
> > >> slow since January. It was a great mystery to me.
> > > Can you get a picture of this ?  It would be wonderful to have for
> > future discussions...
> > >
> > Does that help?
> >
> > <
> > https://www.flickr.com/photos/137684711@N07/38870750440/in/
> > album-72157662535945536/
> >  >
> >
> > Input to the counter is just an AC wall wart with a voltage divider to
> 4Vpp.
> > Now, the frequency has risen to above 50.02 Hz constantly. It is in the
> > middle of the night after all.
> > They have to catch up.
> >
> > BTW I have decided to build an analog phase noise tester of my own. This
> > weekend
> > I did most of the mechanical things, but it is still in a kit state.
> >
> > The pictures are to the left of the 49 Hz-Pic.
> > The 1-to-6 coax relays are part of the switchable lambda/4 delay line,
> > so I can enforce
> > quadrature everywhere above 5 MHz, including unknown amplifiers etc.
> > Still looking for 2 more 1:6 relays.
> >
> > The mixers and dividers are in stereo, so I can do cross correlation in
> > the 89441A.
> > One of the mixer/preamp units is open, the ref oscillators will be
> > MTI-260s on
> > my oscillator carrier board.
> >
> > Have a good night,
> > Gerhard
> >
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Re: [time-nuts] Beware the Casio WaveCeptor analog watch

[Tim Shoppa]

I had the black plastic digital LCD (no hands) waveceptor for 5+ years and
my only complaint about it was the short life of the Casio watch bands and
replacements which rarely lasted longer than a year.

3 years ago I upgraded to a Solar-powered Waveceptor WVA-640 with a metal
band and am very happy with it. It syncs to WWVB every morning 1-3AM all
the way out here on East Coast, and I have never observed it being off by a
fraction of a second during the day.

I have had other (Seiko) watch-hand watches that I had to do the
jiggling-the-hand-stepper-motor-to-be-in-sync thing - but only after
exposure to very close AC magnetic fields. Being within a few feet of large
multi-thousand-amp transformer windings, or just inches of a magnetic tape
degausser, can drive any analog hand watch bonkers, not just the stepper
motor ones. Skip, is it possible that your hand alignment problems are
because you were working near large AC or pulsing DC currents?

Tim N3QE

On Sun, Feb 25, 2018 at 6:52 PM, Skip Withrow 
wrote:

>  Hello Time-Nuts,
>
> For many years I owned a Casio WaveCeptor digital watch and like it a
> lot.  The down side was that the battery had to be replaced every few
> years.  And since I had worn it for many years, the plastic case and
> crystal had taken quite a beating.  Finally, the pin holder that
> secures the band broke - end of watch (except as a 'pocket' watch).
>
> So, I went out and bought a solar powered analog version of the
> WaveCeptor (and vowed not to take it caving).  However, several months
> ago I needed to take an action at an exact time (not ebay) which was a
> miserable fail.  I found that the watch was over a minute off.
>
> I went back and explored the watch manual and found that there is a
> procedure to sync the minute and second hands.  I did this and after
> syncing to WWVB all was good.
>
> Now, a couple of months later I needed the precise time again.
> However I checked my watch before hand and found that it was 8 seconds
> off.  Ahrg!
>
> It appears that the stepper motor position of the second and minute
> hands can be jarred out of sync with normal wear bumps and shocks.
> The trouble is you don't know when it happens (unless you check your
> watch against a trusted source often).
>
> Now I'm seriously considering buying a solar version of the digital
> watch to get rid of the problem.
>
> Regards,
> Skip Withrow
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Re: [time-nuts] CSAC Project(was CSAC purchase)

[Tim Shoppa]

That's a wonderful paper by those Woods Hole guys.

Their temperature-compensated 5 milliwatt crystal oscillators can be
back-corrected (linear drift model) to a few tens of milliseconds over a
year and they make a convincing case they know how to do this.

Their similar graphs for CSAC oscillators are maybe a factor of three
better.

Tim N3QE

On Thu, Jan 25, 2018 at 12:39 PM, gandalfg8--- via time-nuts <
time-nuts@febo.com> wrote:

>
>
> Hi
>
> The CSAC spec sheet calls out an aging rate of 0.9 ppb per month as
> “typical”. There is also a temperature spec of 0.4 ppb. If both are correct
> for your sample (*and* aging is linear ) you would be out by roughly 10 ppb
> per year. There also is a voltage stability spec that might be impacted
> depending
> on how you manage power.
>
> Taking the 30 ppb = 1 second number, you are at a 1 second / year rate
> after 3 years.
> At that point, you have already drifted by a second, if the assumptions
> are correct.
> This makes a massive assumption that the aging stays at the “typical” rate
> for years. It’s a very good guess that it does not. Is it going to be 1/3
> or 1/10
> of typical over that period? Who knows.
>
> Bottom line, you are going to be pretty far from 1 second per 100 years
> with
> a CSAC based wrist watch, if it runs for years (or even for months).  It
> *will*
> do *way* better than a TCXO or OCXO based watch over months or years.
> It’s still not perfect.
>
> Bob
>
> -
>
>  "if it runs for years (or even months)" sounds like an informed comment:-)
>
> When searching for some data recently I came across a report which might
> be relevant.
>
> "A Second Look at Chip Scale Atomic Clocks for Long Term Precision
> Timing", written by
> Alan T. Gardner and John A. Collins of the  Woods Hole Oceanographic
> Institution, details their
> experience with a number of earlier and more recent CSAC modules and their
> findings make
> for very interesting reading.
>
> At the time of writing a copy is available here
>
> www.obsip.org/documents/Gardner_IEEE_Oceans_2016.pdf
>
> Nigel
> GM8PZR
>
>
>
>
>
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Re: [time-nuts] Down-conversion to IF and sampling

[Tim Shoppa]

It would be (as you point out) a bad idea to have the the ADC sampling rate
to be exactly the same as the downconversion oscillator.

In many cases they would both be derived from the same master oscillator.
But the ratios would be consciously chosen to not be simple integer
multiple relations so beating between the ADC and the downconversion
oscillator would get washed out.

This issue of avoiding simple harmonic relationships between receiver
oscillators (and samplers) long predates digital radios, it is a goal in
any superhet to avoid "birdies".

Tim N3QE

On Sat, Dec 23, 2017 at 9:46 AM, Stephan Sandenbergh  wrote:

> Hi All,
>
> Consider the following very common scenario: A perfect RF signal is
> heterodyne down-converted to baseband using an offset oscillator. Let's
> assume this oscillator has x(t) = xo + yot. This produces a time and
> frequency offset baseband signal. Then, this baseband signal is coherently
> ADC sampled using that same offset oscillator.
>
> What would the effect of this coherent ADC sampling be?
>
> See attached diagram. Here I assumed the ADC timebase is a time-dependent
> function of the oscillator offset. However, it feels like I'm making a
> logic error? I can't remember ever seeing anyone accounting for the ADC
> time-base errors in coherent heterodyne down-converter stages. I have
> limited experience though.
>
> Regards,
>
> Stephan.
>
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Re: [time-nuts] accurate 60 hz reference chips/ckts

[Tim Shoppa]

That’s not a problem, that means you’re phase locked instead of just frequency 
locked.

This is the phase-nuts mailing list, right? :-)

Tim N3QE

> On Dec 14, 2017, at 6:19 PM, Alan Melia  wrote:
> 
> I dont think working that way would give a stable clock in the UK. Our 
> frequency can vary more than the US but the number of cycles between 0800 on 
> one day and the next is mandated to be correct (I presume +/- 25 :-))  ). So 
> you would be chasing a moving target, and at no time of the day need the 
> frequency be 50.000Hz
> 
> Alan
> G3NYK
> 
> - Original Message - From: "Jim Harman" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Sent: Thursday, December 14, 2017 10:08 PM
> Subject: Re: [time-nuts] accurate 60 hz reference chips/ckts
> 
> 
>> 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  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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Re: [time-nuts] Simple open source microcontroller solution to tune DDS needed

[Tim Shoppa]

ESP8266 is my favorite as of late. It comes in a "DIP Form Factor" and does
SPI and random DIO very nicely.

Even better, as to user interface, it has Wi-Fi and instead of physical
buttons, the UI can be as simple as buttons on a web page it serves up.

Tim N3QE

On Wed, Dec 13, 2017 at 3:03 PM, Richard (Rick) Karlquist <
rich...@karlquist.com> wrote:

> I need a very simple controller to tune a DDS with up/down
> switches (imagine setting the time on a clock).  A DDS
> chip, such as an AD9836 would go on a PC board and a couple
> of pushbuttons would tell the controller to tune up or
> down.
>
> Before reinventing this wheel, I thought I would see if
> anyone knows of a similar solution that can be leveraged.
> What I would like is both hardware and software, where
> the software could be edited to accommodate the up/down
> buttons.  A last resort would be to write software from
> scratch.  My software skills are extremely limited.
> Cutting and pasting code might work for me.
>
> I need to be able to embed this onto an existing PC board.
> I can't use a preexisting "daughter" card, other than
> to copy the design of the card.
>
> Rick Karlquist
> N6RK
>
>
>
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Re: [time-nuts] Trimble Mini-T Timing Glitches

[Tim Shoppa]

Historical: Ancient (as in Trimble SVeeSix - 20 or more years ago) Trimble
GPS units would have their PPS timing output offset by several milliseconds
when they lost a sufficient number of satellites to maintain a 4D solution.

The PPS offset would jump back and forth by a large step (I recall six
milliseconds) when tracking was borderline.

I do not expect anything modern to have problems like this.

Tim N3QE

On Thu, Nov 30, 2017 at 2:35 PM, Keith Loiselle 
wrote:

> Hello everyone,
>
> I have heard reports of Trimble Mini-T timing glitches with offsets of 1ms
> lasting for about 30 seconds several times during the past week.  Some of
> the dates and times reported are at various locations include:
>
> 23/11/2017, approx 11:00 UTC
>
> 29/11/2017, approx 11:00 UTC
>
> 30/11/2017, approx 12:00 UTC
>
> We have not observed glitches with any of the equipment we have running,
> but we have not had any Trimble units running during the past week.  Has
> anyone else observed similar glitches recently with Trimble or other GPS
> equipment?
>
> Thanks,
>
> Keith
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Re: [time-nuts] Performance verification for time counters

[Tim Shoppa]

At that low a frequency aren’t you actually testing the temperature and time 
stability of the gain controlling components?

Tim N3QE

> On Nov 29, 2017, at 9:04 PM, jimlux  wrote:
> 
>> On 11/29/17 5:53 PM, Bob kb8tq wrote:
>> HI
>>> On Nov 29, 2017, at 8:41 PM, jimlux  wrote:
>>> 
>>> On 11/29/17 3:41 PM, Bob kb8tq wrote:
 Hi
 Needless to say *demonstrating* this 0.001 db sort of gain flatness on a 
 repeater
 out to crazy low frequencies is a bit involved. It *is* a great gig if you 
 happen to be
 a consultant …
 Bob
>>> 
>>> 
>>> 
>>> demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels) 
>>> precision in *any* application is a bit involved.  That's 0.03%
>>> 
>> Yup, now do it at some silly low frequency ( 0.(some number of zeros)1 Hz …. 
>> great way to waste a lot of time.
> 
> 
> That's a volt meter
> 
> It's the "do it at 1 Hz and 10 MHz and every 1 Hz in between" that is the 
> challenge.
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Re: [time-nuts] Allan variance by sine-wave fitting

[Tim Shoppa]

I wonder how much a fitting approach is affected by distortion (especially
harmonic content) in the waveform.

Of course we can always filter the waveform to make it more sinusoidal but
then we are adding L's and C's and their tempcos to the measurement for
sure destroying any femtosecond claims.

Tim N3QE

On Wed, Nov 22, 2017 at 5:57 PM, Ralph Devoe  wrote:

> Hi,
>The fitting routine only takes up 40 uS of the 1 sec interval
> between measurements, as shown in Fig. 1 of the paper. This is less than
> 10(-4) of the measurement interval. It just determines the phase difference
> at the start of every second. I don't think the filtering effect is very
> large in this case.
> The interesting thing is that good results are achievable with such
> a short fitting interval. One way to think of it is to treat the fitting
> routine as a statistically optimized averaging process. Fitting 40 uS, that
> is 4096 points at 10 ns/point,  should reduce the noise by a factor of 64
> (roughly). The single shot timing resolution of the ADC is about 10 pS (see
> Fig. 4), so dividing this by 64 brings you down into the 100's of fs range,
> which is what you see.
>
> Ralph
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Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

[Tim Shoppa]

Orbital determination from Doppler shift is, IMHO, a far more interesting
and fun STEM project than measuring an absolute frequency. And it does not
require MASERs, it only requires low-grade amateur equipment.

Amateur "Crowdsourcing" of orbital data goes at least as far back to ARRL
collecting Sputnik reception reports both by traffic nets and audio tape.

Doppler shift for a VHF transmitter in low earth orbit is several 10's of
kHz over a period of minutes and this pass-information is incredibly useful
for orbit determination.

And science and technology students have been participating in these
determinations for decades too. A very nice review of the work done 25
years ago by students, was published in QST by N6XT:
http://www.setileague.org/articles/ham/kepler.pdf

Tim N3QE
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Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable

[Tim Shoppa]

Isn’t info about what satellites are where, just eye candy and irrelevant to a 
real GPSDO?

Tweaks to the elevation mask ought to be measurable in the PPS quality (if they 
aren’t then they’re irrelevant).

Tim

> On Nov 14, 2017, at 10:39 PM, Mark Sims  wrote:
> 
> The M12 uses different commands for sending a lot of the data since it is 
> tracking more sats and the old commands were limited to 6 or 8 sats.   I 
> doubt it would work the the RFTG.  There might also be a 3V vs 5V problem.
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Re: [time-nuts] Designing an embedded precision GPS time

[Tim Shoppa]

I don't know of any "non-historic" NTP implementation that even attempts to
drift correct the RTC clock.

Now, the RTC clock is useful to set the time at boot before ntpd gets
started.

Tim N3QE

On Tue, Oct 31, 2017 at 8:19 PM, MLewis  wrote:

> If one is building a GPS disciplined NTP Stratum 1 server from a Pi or
> Beaglebone, the "better" quality RTCs seem to be
>
> DS3231 based (DallasSemi/Maxim), Accuracy ±2ppm from 0°C to +40°C, ±3.5ppm
> from -40°C to +85°C
>
> or
>
> NXP:
> PCF2127AT: ±3 ppm from -15 °C to +60 °C
> PCF2127T: ±3 ppm from -30 °C to +80 °C
> PCF2129AT: ±3 ppm from -15 °C to +60 °C
> PCF2129T: ±3 ppm from -30 °C to +80 °C
>
> How does one translate that into an expected 24 hour holdover?
>
> And, are there better choices for a low cost RTC?
>
> Thanks,
>
> Michael
>
> On 31/10/2017 4:47 PM, Bob kb8tq wrote:
>
>> HI
>>
>> TCXO is a very loosely defined term. A part that does +/- 5 ppm -40 to
>> +85C
>> is a TCXO. A part that does +/- 5x10^-9 over 0 to 50C may also be a TCXO.
>>
>> Dividing the total deviation of either one by the temperature range to
>> come
>> up with a “delta frequency per degree” number would be a mistake. You
>> would get a number that is much better than the real part exhibits.
>>
>> Working all this back into a holdover spec in an unknown temperature
>> environment is not at all easy.
>>
>> Bob
>>
>>
>> On Oct 31, 2017, at 4:03 PM, Attila Kinali  wrote:
>>>
>>> Hoi Leo,
>>>
>>> On Sat, 28 Oct 2017 11:14:08 +0100
>>> Leo Bodnar  wrote:
>>>
>>> True. An NTP server does not need to measure time better than 100ns or
>>> so.
>>> 10ns is probably more than good enough. But then, this raises the
>>> question
>>> what your performance metric is that you optimize for?
>>>
>>> If it is hold-over, then this will be limited by the TCXO and how well
>>> you can measure its frequency, which in turn depends on how well you
>>> can measure the PPS pulse. You say that your device is typically within
>>> 4-5ms in 24h of hold-over. That translates to frequency uncertainty
>>> of approximately 5e-8. That's not that good.
>>>
>>
>
>> To summarize: If you want to improve your ntp devices hold over
>> performance
>> you have to improve the frequency measurement and use a better clock
>> modeling.
>> Ie, use a timing GPS receiver and its sawtooth correction, and model the
>> clocks frequency change over time.
>>
>>
>> Attila Kinali
>> --
>>
>
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Re: [time-nuts] inexpensive, black box, GPS or NTP based TTL time capture?

[Tim Shoppa]

picPET -- Precision Event Timer http://www.leapsecond.com/pic/picpet.htm

On Wed, Oct 18, 2017 at 1:33 PM, Rob Seaman  wrote:

> Attila Kinali wrote:
> > On Wed, 18 Oct 2017 08:47:58 -0600
> > Rob Seaman https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts>> wrote:
> >
> > > I’m at the annual planetary sciences meeting (in Provo this year) and
> several
> > > groups have expressed interest in duplicating our setup (details of FO
> > > converters, Schmitt triggers, etc, omitted) in a “cheap black box” to
> quote
> > > one fellow. Lots of people contribute productively to NEO observations,
> > > including amateurs and small teams with little funding. Improving their
> > > timekeeping would help keep rocks from falling on you and your family.
> >
> > What is this black box supposed to do? Just provide a PPS? IRIG-B?
> > Or does it need to have time-stamping capabilities? If so, how many
> > channels?
> >
> > What are your time precision/accuracy requirements?
> >
> > What how cheap is "cheap"? What is the volume?
>
> Thanks for the quick reply. I should have included the subject line in the
> message:
>
> "inexpensive, black box, GPS or NTP based TTL time capture”
>
> Telescope domes are filled with equipment, in particular the camera
> shutter, that can be instrumented to issue a pulse suitable for hardware
> time capture. We use Meinberg IRIG PCIe cards to trap these and read the
> timestamps using their library routines under Linux. “Black box” to the
> person I was talking to meant no IRIG in the dome, no Linux, and no PCIe
> slot, but rather a self-contained unit that syncs to GPS. When last he
> implemented such a feature at another telescope he didn’t even have time
> capture, but rather the device issued a trigger at a specified moment, so
> the timestamp and the shutter opening were inverted. He also seems to
> prefer the timestamps be issued on a serial connection, not via library.
>
> Unlike laboratory instrumentation, a telescope environment needs to be
> both very automated and very forgiving. Money may also be constrained.
> However, telescopes are also often very flexible and I am willing - no,
> eager - to consider completely different arrangements of equipment.
>
> So, reliable timestamping of a TTL input is the ulitmate goal. One channel
> would be sufficient, but multi-channel would not invalidate an option. PPS
> or IRIG-B (DCLS IEEE-1344) are not required, but might form an intermediate
> part of the solution. Reference could be GNSS or possibly NTP.
>
> Precision varies, but milliseconds down to microseconds. Accuracy should
> match the precision, meaning UTC accurate to same. Extra credit for
> multiple timescale support.
>
> Cheap is what I want to know. I see the previous thread on BB-black and
> could imagine a solution using the real time capabilities of that for a few
> hundred bucks, but these are not experimenters, per se. That’s why they
> want a black box. Volume is one to several, but could imagine a bulk order
> if savings were significant. Hundreds of dollars might be the price point.
>
> Thanks!
>
> Rob Seaman
> University of Arizona
>
>
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Re: [time-nuts] Weird GPSDO behavior - update

[Tim Shoppa]

Is there a way you can force your currently disciplined oscillator to
free-run, and log the phase difference between oscillator and GPS over a
couple of days?

Tim N3QE

On Tue, Oct 3, 2017 at 2:15 PM, Skip Withrow  wrote:

> Hello Time-Nuts,
>
> Well, I think I know a little more about my GPSDO problem, but
> probably have more questions now than before.  Thanks for all the
> replies to the first post with thoughts and suggestions.
>
> I first tried restarting Lady Heather and doing a cold boot on the
> NTGS50AA (then entering the same disciplining values). Same behavior.
>
> I let it run over the weekend and the same behavior happened on
> Saturday and Sunday morning.
>
> So, yesterday (Monday morning) I changed the gain to the gain of the
> oscillator (.0072Hz/V), damping to 1.2, and time constant to 900s.  On
> the attached PRS10-2 plot you can see that it quickly settled.  This
> morning, it looks like all is well from the plot (about an hour before
> the furnace kicks in at the right of the plot).  HOWEVER, when the
> plot is expanded there is still funny business going on with the DAC
> control voltage at the same time of day.  I just think the changed
> parameters limit the disturbance.  The expanded plot is the attached
> PRS10-1.
>
> At this point I'm beginning to think that the NTGS50AA is the issue,
> but there are lots of questions left.
>
> 1. There are various version of the NTBW50AA/NTGS50AA GPS/operating
> firmware.  Mine is 10.3 and I notice that it has the LH 'ro'
> designation (as does the 10.4 version).  The 10.5 version does not
> give the LH ro notice.  Maybe it behaves better with the disciplining?
>  I will have to give a 10.5 a try.
>
> 2. Why does the glitch occur at 8am in the morning?  Will have to try
> powering the NTGS50AA up at different times and see it the glitch
> moves around.
>
> 3. Which disciplining parameters are affected by this glitch and which are
> not?
>
> 4. Have other people seen this same behavior?  Does it happen on
> Thunderbolts too?
>
> I'll update again when I have more data.
>
> Regards,
> Skip Withrow
>
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Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Tim Shoppa]

Civilian receivers generally do not measure absolute strength but instead
report S/N. The spoofer could fake up a reasonable amount of noise to get a
wimpy S/N with a much stronger signal.

Tim.

On Mon, Aug 14, 2017 at 1:40 PM, ken Schwieker 
wrote:

> Wouldn't monitoring the received signal strength and noting any non-normal
> increase (or decrease) level change indicate possible spoofing?  The
> spoofing station would have no way to know what the target's
> received signal strength would be.
>
> Ken S
>
>
> ---
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>
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Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Tim Shoppa]

In some sense the "jump everyone to the airport 32km away" is a
too-simplistic case because it's too easy to detect.

Let's just arbitrarily place 100nanoseconds as the threshold for detectable
time jump indicating that you're being spoofed. Yes modern timing receivers
do better than that all the time but navigation receivers are not timing
receivers.

The spoofing transmitter would need to know the single target's
3-dimensional location to 100 feet, to avoid detection of a spoofing
attempt, then. This seems possible or even likely, especially in the case
of a spoofing demonstration with slow seagoing vessels, or maybe even road
vehicles known to be traveling on a given highway combined with other
roadside sensors.

After the spoofer had acquired the spoofing target that way, giving it a
false (but not inconceivable) course to the wrong location seems possible.
If you know something about the craft's ability for inertial guidance you
would keep your fake course within those parameters.

So it all gets much easier ifyou can set up the local detection net at key
locations that a spoofing target is likely to travel through. A narrow
strait or a highway intersection. It all gets much harder when you have
multiple targets in your field of view that you want to spoof especially if
you can't follow them closely.

But maybe as long as all the GPS manufacturers are focusing on low
time-to-first-fix, the target GPS will always be too willing to believe a
completely arbitrary location. Us time-nuts don't mind surveying for days.
Real GPS positioining users want the answer much more quickly!

Tim N3QE



On Mon, Aug 14, 2017 at 12:51 PM, Attila Kinali <att...@kinali.ch> wrote:

> On Mon, 14 Aug 2017 12:09:43 -0400
> Tim Shoppa <tsho...@gmail.com> wrote:
>
> > I think if you are only trying to spoof a single receiver it would be
> > possible to walk a spoofed time/space code in a way that time moved
> without
> > so obvious of a discontinuity. I'm sure there would be effects a time-nut
> > could notice still.
>
> Not really. Unless you have a multi-antenna setup (see jim's email),
> you have nothing to compare the signal to. Even an ideal reference
> clock in your GPS receiver does not help, as the attacker could be
> tracking you in such a way that you will never see a discontinuity
> in time or position and that all the other sanity checks you do
> still don't show anything.
>
> With a two antenna setup, you can already check whether the phases
> add up to what you expect them to be, given your position relative
> to the satellites position. You do not need 3 antennas as a potential
> attacker can spoof the phase of some satellites correctly, but not
> of all at the same time. This at least gives you a spoof/no-spoof signal.
>
> With an antenna array you can do some masking of spoofers (ie placing
> a null where the spoofer comes from). But this increases the cost and
> complexity of the system super-linear with the number of antennas.
> Maybe one way to do it, would be to use a single receiver with a stable
> reference clock and switch between antennas in short succession. Ie similar
> to how the early single channel GPS receivers worked, but for antennas
> instead of SVs. But I have no idea how easy/difficult this would be
> to do and how well it would work against spoofers.
>
> Attila Kinali
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Tim Shoppa]

Bringing this back around to time-nuts - wouldn't the timescale
discontinuity at the receiver, be a powerful clue that spoofing was going
on? But these being navigation receivers they aren't looking so critically
at the time.

Presumably this was a single-transmitter jammer that pretended it was a
whole GPS constellation.

A 32 kilometer jump in position would've been a 10 to 100 microsecond time
jump for at least some of the receivers in that section of the Black Sea.
And 10 microseconds sticks out like a sore thumb to a time nut.

I think if you are only trying to spoof a single receiver it would be
possible to walk a spoofed time/space code in a way that time moved without
so obvious of a discontinuity. I'm sure there would be effects a time-nut
could notice still.

Tim N3QE


On Sat, Aug 12, 2017 at 5:23 PM, John Allen 
wrote:

> FYI, John K1AE
>
> -Original Message-
> From: YCCC [mailto:yccc-boun...@contesting.com] On Behalf Of ROBERT
> DOHERTY
> Sent: Saturday, August 12, 2017 9:26 AM
> To: YCCC Reflector
> Subject: [YCCC] Fwd: Re: [Radio Officers, ] Ships fooled in GPS spoofing
> attack suggest Russian cyberweapon
>
> As if there were not enough problems in the world .
>
> Whitey  K1VV
>
> > Date: August 12, 2017 at 7:37 AM
> > Subject: Re: [Radio Officers, ] Ships fooled in GPS spoofing
> attack suggest Russian cyberweapon
> >
> > Ships fooled in GPS spoofing attack suggest Russian cyberweapon
> >
> > News from: New Scientis (article reported by R/O Luca Milone –
> IZ7GEG)
> >
> > https://www.newscientist.com/article/2143499-ships-fooled-
> in-gps-spoofing-attack-suggest-russian-cyberweapon/#.
> WY6zNfZq1VA.google_plusone_share https://www.newscientist.com/
> article/2143499-ships-fooled-in-gps-spoofing-attack-
> suggest-russian-cyberweapon/#.WY6zNfZq1VA.google_plusone_share
> >
> >
> > On date: 10 August 2017
> >
> > By David Hambling
> >
> >
> > Reports of satellite navigation problems in the Black Sea suggest
> that Russia may be testing a new system for spoofing GPS, New Scientist has
> learned. This could be the first hint of a new form of electronic warfare
> available to everyone from rogue nation states to petty criminals.
> >
> >
> > On 22 June, the US Maritime Administration filed a seemingly bland
> incident report. The master of a ship off the Russian port of Novorossiysk
> had discovered his GPS put him in the wrong spot – more than 32 kilometres
> inland, at Gelendzhik Airport.
> >
> >
> > After checking the navigation equipment was working properly, the
> captain contacted other nearby ships. Their AIS traces – signals from the
> automatic identification system used to track vessels – placed them all at
> the same airport. At least 20 ships were affected
> http://maritime-executive.com/editorials/mass-gps-spoofing-
> attack-in-black-sea .
> >
> >
> > While the incident is not yet confirmed, experts think this is the
> first documented use of GPS misdirection – https://www.marad.dot.gov/
> msci/alert/2017/2017-005a-gps-interference-black-sea/  a spoofing attack
> that has long been warned of but never been seen in the wild.
> >
> >
> > Until now, the biggest worry for GPS has been it can be jammed
> https://www.newscientist.com/article/dn20202-gps-chaos-how-
> a-30-box-can-jam-your-life/  by masking the GPS satellite signal with
> noise. While this can cause chaos, it is also easy to detect. GPS receivers
> sound an alarm when they lose the signal due to jamming. Spoofing is more
> insidious: a false signal from a ground station simply confuses a satellite
> receiver. “Jamming just causes the receiver to die, spoofing causes the
> receiver to lie,” says consultant David Last
> http://www.professordavidlast.co.uk/ , former president of the UK’s Royal
> Institute of Navigation.
> >
> >
> > Todd Humphreys http://www.ae.utexas.edu/faculty/faculty-directory/
> humphreys , of the University of Texas at Austin, has been warning of the
> coming danger of GPS spoofing for many years. In 2013, he showed how a
> superyacht with state-of-the-art navigation could be lured off-course by
> GPS spoofing. “The receiver’s behaviour in the Black Sea incident was much
> like during the controlled attacks http://onlinelibrary.wiley.
> com/doi/10.1002/navi.183/full  my team conducted,” says Humphreys.
> >
> >
> > Humphreys thinks this is Russia experimenting with a new form of
> electronic warfare. Over the past year, GPS spoofing has been causing chaos
> for the receivers on phone apps in central Moscow to misbehave
> https://themoscowtimes.com/articles/the-kremlin-eats-gps-
> for-breakfast-55823 . The scale of the problem did not become apparent
> until people began trying to play Pokemon Go. The fake signal, which seems
> to centre on the Kremlin, relocates anyone nearby to Vnukovo Airport
> http://www.thetruthaboutcars.com/2017/01/bizarre-gps-
> spoofing-means-drivers-near-kremlin-always-airport/ , 32 km 

Re: [time-nuts] Can Lady Heather set PC time directly from a TrimbleThunderbolt?

[Tim Shoppa]

I'm all for building NTPD from source (as a former refclock developer).

But for those not building from source and wanting to install on Windows,
Meinberg NTPD's self-installing package is very easy and does everything
right.

They distribute this for free. I think they've done a great service. And
having real NTPD is so much superior to the many poor quality commercial
programs out there that a newbie might otherwise install.

Tim N3QE

On Fri, Aug 4, 2017 at 2:28 PM, Chris Albertson 
wrote:

> On Fri, Aug 4, 2017 at 7:39 AM, Chris Wilson  wrote:
>
> >
> > Thanks  to  everyone  for the replies, so basically would you say that
> > with  a permanent internet connection I should forget using GPS time to
> > set  the  PC  clock  and  just use Meinberg or NTP (which is what I am
> > currently using and seems to work just fine)?
>
> You'd be using the same NTP software in either case.  The difference
> is it you were to add a GPS reference clock to the current setup.
> Even with GPS you's till want to keep the internet based reference
> clocks.
>
> Currently your PC clock might be accurate that the few milliseconds
> level.  Adding a GPS receiver into the mix will improve accuracy to
> the tens of microseconds level.   You'd gain abut two orders of
> magnitude over the current setup.
>
> Do you need this?  I can think of uses for a highly accurate clock in
> amateur radio.  Perhaps you are measuring propagation delay.  Doing
> this 100 times more accurately might be helpful.On the other hand
> maybe you only need log files time stamps to be with a second or so of
> correct? When I got into this may application was pointing
> telescopes and measuring the light from variable stars.Usually you
> can start with you application and work backwards to place a
> requirement on time accuracy
>
> On the other hand this is a "time nuts" list and some people here just
> want the BEST they can get.
>
> I'm not a fan of Meinberg because of the way they market freely
> available software.
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] A look inside the DS3231

[Tim Shoppa]

On the subject of low-current 32kHz oscillators:

DS3231 spec says typical 1uA for timekeeping and circa 600uA for
temperature conversion. I understand they periodicailly kick the
temperature conversion on but only for extremely short duty cycles and this
is included in the 1uA.

Standard DS12887 spec was 500nA with the oscillator and counter logic
running. This did not have any temperature conversion/compensation.

RCA published a 4007-based 32kHz oscillator that was circa 1uA but I think
that spec was at 1.5V. RCA got a patent on putting a resistor in the drain
of the first stage to slow it down and reduce power consumption to get down
to 1uA. So in the DS12887, Dallas figured out how to go at least a factor
of two lower in power. I would imagine there's a series of patents by watch
companies on this subject as well probably all back in the 1970's and
1980's.

Tim N3QE

On Sat, Jul 29, 2017 at 2:32 PM, Pete Stephenson  wrote:

> On Thu, Jul 27, 2017, at 09:46 PM, Trent Piepho wrote:
> > Looks like it still says "DALLAS SEMICONDUCTOR" to the left of Maxim.
> > Maybe Maxim only wanted to change the mask enough to find some empty
> > space to sign it?
>
> It does indeed say "DALLAS SEMICONDUCTOR".
>
> I managed to get some high-quality photos using the microscope's
> on-board camera and have updated the photo album at
> https://imgur.com/a/0zudj with the newest ones (they're the
> all-rectangular photos below the two circular photos). There's some
> high-resolution composite images.
>
> Some things I found interesting:
> - There's a section just above the "Maxim" part that has several
> snippets of text ("17A3", "16A3", etc.). In normal light, each of these
> bits of text is a different color, where the colors correspond to
> different layers of the chip. Each bit of text has a different depth of
> focus, indicating they're physically closer or further from the lens.
> Does anyone know what material the colors might correspond to?
>
> - There's several square grids of circles-in-squares circuit elements. I
> have no idea what these are.
>
> - I find it remarkable that this circuit can operate on less than a
> microamp during normal usage, including temperature conversion.
>
> The DS3231 has on-board temperature monitoring to correct the crystal
> frequency: is this something where they would have bothered putting a
> separate sensor next to the crystal itself, or are the die and the
> crystal are close enough and in the same package that they could use an
> on-die sensor like a diode and call that "good enough"?
>
> Cheers!
> -Pete
>
> --
> Pete Stephenson
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Re: [time-nuts] unknown GPSDO

[Tim Shoppa]

The original Brooks Shera unit was 20 years ago and is pretty well
documented in QST and his website. In the original the loop filter
timeconstant was set by jumpers or DIPswitches. And I think the EFC gain
factor was set somewhere else (DIPswitch? Resistor network? Both?)

Shera's webpage documents some improvements and changes up through 2001 but
there have been an incredible number of variations out there in the wild as
folks move parameters that used to be set in hardware/DIPswitches to
firmware with LCD config screens etc. I think the OP's unit shows a decade
or more of evolution past what Shera documents.

Is there a "Brooks Shera GPS family tree" out there showing recent
evolution of the design?

Tim N3QE

On Tue, Jul 18, 2017 at 11:10 AM, David C. Partridge <
david.partri...@perdrix.co.uk> wrote:

> ISTR that you started it with a short time constant to get locked,  and
> once you had lock you would increase the time constant in a few steps to a
> final value of (say) 1000s or so.
>
> Dave
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Volker
> Esper
> Sent: 18 July 2017 14:15
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] unknown GPSDO
>
> Thanks so far. I will have a look at the docs.
>
> The machine is running well, particularly the OCXO is performing very good
> when free running (without GPS signal). It is stable and its ADEV looks
> good (2E-10 at 10s). Not so the overall ADEV (when GPS locked)
> (1E-5 at 10s). It seems to not having the right filter time constant what
> had to be much longer. As I understand the documents, the filter constant
> can be programmed and I will experiment whith that this afternoon.
>
> Thank you
>
> Volker
>
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Re: [time-nuts] Papers on timing for lunar laser ranging

[Tim Shoppa]

The gizmo with a CRT is a Specific Products WWV receiver. I'm not sure exactly 
which model, some had the ability to show on the CRT the CRT phase between 
local clock and WWV via pips, others would show phase via Lissajous figures.

Tim N3QE

> On Jul 12, 2017, at 4:46 PM, Bob kb8tq  wrote:
> 
> HI
> 
>> On Jul 12, 2017, at 3:27 PM, Tom Van Baak  wrote:
>> 
>> 2 items:
>> 
>> 1) I ran across another link related to lunar timing. Last year Carroll 
>> Alley died (89). To me he's famous for his cesium and H-maser relativity 
>> experimence in the 1970's. But he was also the PI for the Apollo Lunar Laser 
>> Ranging Retroreflector experiments. More info here:
>> 
>> https://www.nasa.gov/vision/space/features/21jul_llr.html
>> 
>> http://umdphysics.umd.edu/about-us/news/department-news/1128-carroll-alley-june-13-1927-february-24-2016.html#!Alley_Lunar_Laser_Ranging_Retroreflector_1
>> 
>> https://en.wikipedia.org/wiki/Carroll_Alley
>> 
>> 2) That second link above has some wonderful photos.
>> 
>> http://umdphysics.umd.edu/images/igallery/resized/1-100/Alley_Lunar_Laser_Ranging_Retroreflector_1-99-700-300-100-c.jpg
>> 
>> Spot the Austron 1250A, Sulzer 2.5, and GenRad(?) quartz frequency 
>> standards. Anyone recognize more gear?
> 
> Like the GR synthesizer above the GR frequency standard? Both are from the 
> “dark gray” era rather than the later “light gray” period. 
> 
> Not quite sure about the gizmo top left (next to the Austron) with the CRT? 
> in the middle of the pannel. 
> 
> Bob
> 
>> 
>> /tvb
>> 
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Re: [time-nuts] PI Zero W LED Desktop Clock with 10ths of Seconds / NTP disciplined

[Tim Shoppa]

I have been thinking about doing similar with an ESP8266 controller (which
start around $2). All the other machines in my house are locked to GPS at
either stratum 1 or stratum 2 so there are plenty of local good time
sources.

The ESP8266 has 64K, WiFi and a IP stack but does not run a real operating
system or ntpd. It does have kind of a multithreading scripting executive
(LUA). I would "homebrew" my own time discipline and peer selection
algorithms using much simpler tools, rather than full-blown ntpd. Simply
asking a local computer for ntp time is straightforward enough, then I add
some local time and frequency discipline on top of that.

After all, real NTP a couple decades ago ran on Fuzzballs which were
PDP-11's. I think at first they just calculated time offset from the 60Hz
line clock (16ms granularity) but I also recall a millisecond tick crystal
clock they could do frequency discipline on? All that fit on a PDP-11
nicely so I ought to be able to get much of it into an ESP8266.

Tim N3QE

On Sat, Jul 1, 2017 at 9:45 PM, M. George 
wrote:

> I just finished an LED clock kit that can be found on hackaday.io by Nick
> Sayer.   Below is a link to a couple of one take videos
>  I made of the clock.  It's a
> nice piece of eye candy.  I haven't see an LED clock kit like this that
> uses a lite distribution of Linux where you have a server for the clock
> running NTP.  The code that runs the clock is a C program that you compile
> and run when the OS boots up.  It's nice that the PI Zero W is wireless for
> the clock... where it looks like a regular desk clock, but for the time-nut
> you can ssh in and check things out and look at loopstats etc...an NTP
> driven desk clock with 10ths of seconds.
>
> YouTube Video :
> https://www.youtube.com/watch?v=cAXFDt3PBJg
>
> Pictures
>  2FRaspberry+PI%2FPI+Zero+W%2FDesktop+NTP+Clock>
> : http://www.nc7j.com/pa/main.php?cmd=album=NG7
> M%2FRaspberry+PI%2FPI+Zero+W%2FDesktop+NTP+Clock
>
> I have no connection to the creator of the project or reason to give the
> project a plug other than I had fun making the simple kit and setting up
> Raspbian Lite to drive the PI Zero W., The creator of the kit is Nick Sayer
> on hackaday.io
> , I
> suspect he might get a few more looks at this project now:
> https://hackaday.io/project/20156-raspberry-pi-zero-w-desk-clock
>
> Enjoy, Max NG7M
>
> --
> M. George
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Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Tim Shoppa]

Whoops. Since Tom invited us to this off topic discussion, my two minor 
complaints about PowerPoles:

1: No make-first for ground. This is actually alleviated by other Anderson 
connector styles - in the 15A range they have a make first pin (which breaks 
the hermaphodicity). And in the big-boy multi hundred amp range they use a 
secondary make-last set of contacts to authorize application of power by the 
source.

Without a make first for ground you worry that some flimsy signal ground might 
be asked to carry 30Amps.

2: Not locking. Well at least we aren't going to be dangling a piece of 
equipment falling off edge of bench by the power pole.

Despite the above two caveats I don't have anything better. Molex connectors 
aren't really locking either and the certainly don't last at their rated 
current when exposed to an automotive or outdoor environment.

Tim N3QE

> On Jun 22, 2017, at 7:13 AM, Tim Shoppa <tsho...@gmail.com> wrote:
> 
> One of the complaints, was that 
> 
>> On Thu, Jun 22, 2017 at 3:19 AM, Tom Van Baak <t...@leapsecond.com> wrote:
>> Wes, Don,
>> 
>> I am quite surprised at the negative reaction to Anderson Power Pole 
>> connectors. I have found them the best DC connector out there. I have used 
>> them for a decade or two for all my DC feeds and have never had a problem: 
>> in my home lab, my car, even for my laptop charger. They are inexpensive, 
>> reliable, genderless (hermaphroditic) and easy to crimp. I use them for my 
>> 5V, 12V, 24V, and 48V supplies as well as my DC backup systems.
>> 
>> What on earth are you doing with them that causes them to disconnect? I 
>> mean, they are not meant for towing or lifting or rappelling. For critical 
>> applications there is a plastic gizmo that keeps them mated; or just use a 
>> square or figure 8 knot on the cables.
>> 
>> /tvb
>> 
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Re: [time-nuts] Hints on PPS Buffer design...

[Tim Shoppa]

Clay, as to "why 20 ohms out", there is a long-time-nominal 50 ohm PPS
convention that calls for 5V pulses to be delivered into a 50 ohm load.

If the driving voltage was 5V and source resistance was 50 ohms, then you'd
never get more than 2.5V into the load.

Different references across the net show 5V chips driving parallel 5x100
ohms, or 5x47 ohms. These are all attempts at getting more than 2.5V and
closer to 5V into the load. If you run the driver chip at 6V (which is
actually permissible for some HC-derived logic chips) then you can get even
closer to 5V into a 50 ohm load.

Most devices that consume this 5V-into-50-ohm signal are actually fine with
less than 2.5V but that's very vague.

There are real coaxial cable driver chips as well as arrangements of
bipolar transistors that do a very good driving long 50 ohm coax cables to
5V. These were very popular in the 1960's and 1970's as coax drivers for
mainframe/minicomputer computer peripherals, and are still available today
but not nearly so popular.

A much more popular cable driver standard from the past 20 years would be
LVPECL or LVDS but those are nominally differential and everyone seems to
insist on coax even today.

Tim N3QE

On Sat, Jun 17, 2017 at 4:15 AM, Clay Autery  wrote:

> Trying to pin down a reasonably optimal buffer design for bringing PPS
> out...  I've looked at all the references, like the i3detroit.org site
> et al.
>
> Of the few schematics and devices I see, most are using a hex inverter
> (1 into the other 5 paralleled with series resistors for "balance" and
> setting output impedance?
>
> Q:  Why does everyone pick FIVE x 100 Ohm resistors?  That's 20 Ohm out,
> not counting the gate impedance on the hex inverter...
>
> Q2:  Anyone have a reference to the math for choosing the resistors for
> setting a 50 Ohm nominal out INCLUDING determining and including the
> gate impedance of a particular part.
> (Right now, I am going to use the TI SN74AC04 Hex Inverter)  I saw a
> refernence in the archive referring to a 4 gate setup using a different
> part needing 187 Ohm resistors... thus I can only include that I need to
> use something slightly more than 250 Ohms on a 5 gate parallel setup)
>
> Q3: It's only a 1Hz frequency, but is low inductance a desired trait of
> the chosen resistors?
>
> I'm sure there are others...
>
> Thanks!
>
> --
> __
> Clay Autery, KY5G
> MONTAC Enterprises
> (318) 518-1389
>
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Re: [time-nuts] Poor man's oven

[Tim Shoppa]

Here is a national new-technology of the art crystal oven from 1956: 

http://tf.boulder.nist.gov/general/pdf/1642.pdf

Using the phase change properties of p-dibromobenzene it keeps temperature 
constant to 0.01C. It notes other organic compounds can be used for different 
temperature ranges.

Did this oven technology ever get beyond lab use and into the real crystal oven 
world?

I know in the past decade "thermowax" has been used in Honda lawnmower 
auto-chokes. I don't think it's ever supposed to be anything but solid, but it 
undergoes a phase change that causes it to expand by a large fraction.

Tim N3QE



Sent from my VAX-11/780
> On Jun 5, 2017, at 5:16 AM, Clint Jay  wrote:
> 
> There's a few 'OCXO' designs out there, I'm not qualified to comment on the
> timenutty quality of them but someone else mentioned Hans Summers offerings
> and I would offer Roman Black's simple design (if it's not been mentioned
> already):
> 
> http://www.romanblack.com/xoven.htm
> 
> I've no idea if it's useful but it's ridiculously simple to implement.
> 
> Both Hans' and Roman's designs are 'on the list' of things to try for
> myself at some point.
> 
>> On 5 June 2017 at 09:56, Stephen Tompsett  wrote:
>> 
>> Not quite as simple as the PTC, an alternative may be:
>> 
>> http://shop.kuhne-electronic.de/kuhne/en/shop/accessoires/
>> crystal-heater/Precision+crystal+heater+40%C2%B0+QH40A/?card=724
>> 
>> No it probably doesn't hold the crystal at it's optimum turn over
>> temperature, but it will keep the temperature of a crystal approximately
>> constant especially on a windswept hilltop.
>> 
>> 
>>> On 05/06/2017 09:35, Ulf Kylenfall via time-nuts wrote:
>>>  The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand
>> they were marketed by Murata.
>>> I once purchased a small amount of theseand used them as "poor man's
>> ovens".
>>> Although not perfect by far, they did theirjob and kept my UHF gear
>> stable.
>>> Murata dropped that product many yearsago and I have not been able to
>> findany similar product. The Posistors arelisted by eg. Digi-key but they
>> do not stock them.
>>> Ulf - SM6GXV
>>> 
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>>> 
>> 
>> --
>> Stephen Tompsett
>> 
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>> 
> 
> 
> 
> -- 
> Clint.
> 
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
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Re: [time-nuts] poor-man's oven

[Tim Shoppa]

Bob, at the same time, look at all the guys here who absolutely insist that
the only way to use a double-oven OCXO is to put it in a tightly
temperature controlled environment. "Nuts", yes, but that's why we're here!

I myself have been extremely disappointed with the aging characteristics of
low-end TCXO's. They seem to age even worse than plain old crystal
oscillators, My theory, is this is because the temperature compensation
components are themselves aging more than an AT cut crystal does by itself,
but I've never ripped into one (they're way too tiny to rip into anyway!).

Tim N3QE

On Sun, Jun 4, 2017 at 9:36 AM, Bob kb8tq  wrote:

> Hi
>
> The gotcha is that you have multiple systems working against each other.
> The crystal in the TCXO has
> one temperature characteristic. The compensation in the TCXO has a
> temperature characteristic. They
> cancel each other out to a limited degree. The residual slope may (or may
> not) be as shallow as you
> might think. Your PTC is at an arbitrary point on the residual curve. A
> somewhat more subtle issue is
> the gradient between your PTC, the crystal, and the compensation as it
> cycles.
>
> If the TCXO really isn’t a full TCXO, then some of this goes away. A +/- 2
> ppm 0-50C “TCXO" may not have
> any compensation in it at all. Some 0 to 70C parts are done as 2 ppm 0 to
> 50 and only compensated at the
> hot end. They actually may be worse with the PTC than at room...
>
> Yes this all assumes an AT cut in the TCXO. That’s a pretty good bet ….
>
> Bob
>
>
> > On Jun 4, 2017, at 8:13 AM, jimlux  wrote:
> >
> > I recall some years ago folks were talking about putting a PTC
> thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the frequency as
> a sort of poor-man's OCXO.
> > It's also referenced at
> > http://www.setileague.org/askdr/xtaloven.htm
> > where he says "order of magnitude improvement" with no numbers (from 1%
> to 0.1% or from 1 ppb to 0.1 ppb?)
> >
> > I wonder how well that actually works.
> >
> > Say you bought an inexpensive (perhaps non TC) XO and an equally
> inexpensive thermistor, glued on on the other, hooked em both up to 3.3 or
> 5V.
> >
> > Yeah, there's issues with room air blowing on it, and tolerances in both
> the XO and thermistor, so your absolute frequency accuracy may not be so
> hot. But what sort of medium to long term performance can one expect.
> >
> > I did some searches, because I'm sure we've discussed this before, but I
> couldn't find it.  There was some stuff from Oct 2007, but that was in the
> context of a more complex circuit, and the thermistor was the sensor.
> (discussions of TE devices too)
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Re: [time-nuts] Next Aug 21 eclipse and time flow --> WWV carrier phase

[Tim Shoppa]

Bob, unlike the guys who have many watts of 10MHz running around their labs
via multiple distribution amplifiers, I do not have a big problem with my
dinky 10MHz reference leaking into my radio antenna :-).

This fall the "best band" for WWV for me during daylight eclipse would be
15MHz. 10MHz would have a usable but weaker signal mid-day too.

I was thinking I could synthesize a clean 14.99MHz from my 10MHz, put that
into a mixer along with WWV at 15MHz, and send the 10kHz beat note into one
channel of a PC sound card. The other channel of the sound card could
monitor the Z3801A's 1PPS square wave output, or maybe just the square wave
from dividing 10MHz down to audio frequency square wave. That would allow
me to post-process out any variation in sound card clock.

I should read up on what the FMT guys do. They must do something like this.
I work Connie K5CM almost every week anyway but we are just exchanging
serial numbers, not talking about FMT techniques :-).

Tim N3QE

On Mon, May 29, 2017 at 8:30 AM, Bob kb8tq <kb...@n1k.org> wrote:

> Hi
>
> There are a *lot* of SDR boards out there today. The HackRF One is a pretty
> cheap one (you get what you pay for …). They go up to some very expensive
> setups by National Instruments / Ettus. Most of them allow for an external
> clock
> input. The usual isolation issues will still apply when checking WWV at 10
> MHz.
> Coming up with isolation vs your local standard will be really tough. I
> would aim
> at 5 and 15 MHz. Of course if you have a Lucent KS box, that sort of rules
> out
> 15 MHz :)
>
> Bob
>
>
>
> > On May 29, 2017, at 8:03 AM, Tim Shoppa <tsho...@gmail.com> wrote:
> >
> > During regular night/day cycles I can just barely observe the night-day
> > shift in WWV propagation from Colorado to my location near Washington DC,
> > using the NTP WWV audio refclock. It amounts to a few hundred
> microseconds
> > of shift. I last touched that code about 15 years ago.
> >
> > Now that I have a 10MHz GPS OCXO (well, I've had that for about 15 years
> > too, getting that was the reason I stopped dinking with the WWV audio
> > refclock) I wonder if there's some simple hardware I could build that
> would
> > let me do superior carrier-phase type measurements on WWV propagation.
> If I
> > could see the night-day shift more clearly then I might see an
> ionospheric
> > effect during the upcoming August 21 eclipse, which nicely traces a path
> > from west to east not too far off the line between Ft Collins and my
> > location.
> >
> > Tim N3QE
> >
> > On Sun, May 28, 2017 at 6:17 PM, 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] Next Aug 21 eclipse and time flow

[Tim Shoppa]

During regular night/day cycles I can just barely observe the night-day
shift in WWV propagation from Colorado to my location near Washington DC,
using the NTP WWV audio refclock. It amounts to a few hundred microseconds
of shift. I last touched that code about 15 years ago.

Now that I have a 10MHz GPS OCXO (well, I've had that for about 15 years
too, getting that was the reason I stopped dinking with the WWV audio
refclock) I wonder if there's some simple hardware I could build that would
let me do superior carrier-phase type measurements on WWV propagation. If I
could see the night-day shift more clearly then I might see an ionospheric
effect during the upcoming August 21 eclipse, which nicely traces a path
from west to east not too far off the line between Ft Collins and my
location.

Tim N3QE

On Sun, May 28, 2017 at 6:17 PM, iovane--- via time-nuts  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] LPFRS phase ripple?

[Tim Shoppa]

Matthias, are the units all over in the same thermal environment when you test 
them? 

A period of 150s or so in a wobble sounds like a not perfectly damped thermal 
cycle time of a lightweight oven or lamp.

Reminds me a little of the unit to unit variation in HP Wien Bridge oscillator 
amplitude stability (also a lamp!)

Tim N3QE

> On May 23, 2017, at 3:40 AM, Matthias Jelen  wrote:
> 
> Hello Time-Nuts,
> 
> i´ve been playing with some Rbs recently.
> 
> I compared two LPFRS-01 to a PRS-10. One seems to behave quite well (compared 
> to the specs given here: 
> http://www.spectratime.com/uploads/documents/isource/iSource_LPFRS%20Spec.pdf)
>  - short term stability specs are met), the other one shows quite some phase 
> ripple (appx. 1 ns RMS with a frequency around 0.007 Hz) which spoils ADEV in 
> the 60 - 200s range, very similiar to the typical GPSDO bump. Long term 
> stabilty is OK.
> 
> Unfortunatly I didn´t find any schematics on the web. Has anyone encountered 
> a similiar problem with this unit? Any idea were this might come from? My 
> first guess would be a problem in the control loop locking the VCXO to the 
> Rb, but I have no clue which time constants are used in the PLL.
> 
> Any hints are appreciated.
> 
> Regards,
> 
> Matthias
> 
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Re: [time-nuts] Looking for info on Trimble 16634-10

[Tim Shoppa]

Bob, that was 16.368MHz, an extremely common crystal to find in the first
couple generations of GPS receivers. 16.368 MHz is 16 times the 1.023 MHz
C/A GPS signal chipping rate; multiplied by 96.25 to get the 1575.42 MHz L1
frequency and multiplied by 75 to get the 1227.60 MHz L2 frequency.

Tim N3QE

On Tue, May 23, 2017 at 7:24 AM, Bob kb8tq  wrote:

> Hi
>
> If you guess that the design started in 90 and ran through 93~94 that
> is a very early unit for Trimble. 16.384 MHz suggests some sort of telecom
> or data bus application.
>
> Bob
>
> > On May 22, 2017, at 11:48 AM, Scott Armstrong  wrote:
> >
> > Hi Guys,
> >
> > I popped open the case.  Not too crowded in side. The case is an extruded
> > aluminum case that has the back endplate  welded on.
> >
> > There are 4 board assemblies in the case.
> >
> > *Interface board that connects the 22 pin connector to the other two
> boards.
> > * Power supply board. (12016-00). Main component looks to be a DC-DC
> > converter made by Computer Products.
> > * Main board (14636-)  This board has a 16.368 MHz osc made by NDK.
> > * A daughter board (14789E) which is the receiver and is attached to the
> > main board.
> >
> > Date codes I see are 89, 91, 92 and 93  so unit was probably assembled in
> > '93.
> >
> > Maybe some of the assembly numbers will be recognizable if they are used
> in
> > other units.
> >
> > Thanks,
> > Scott AA5AM
> >
> >
> > On Sat, May 20, 2017 at 12:33 AM, Bill Hawkins 
> wrote:
> >
> >> FWIW, that looks like aviation equipment (gov't or civil), with a
> >> locking connector.
> >>
> >> That stuff is designed for minimum size and weight. You might find the
> >> inside of the box quite cramped.
> >>
> >> Buying aviation parts is even more expensive than buying boat parts.
> >>
> >> Bill Hawkins
> >>
> >>
> >> -Original Message-
> >> From: time-nuts on behalf Of Bob Bownes
> >> Sent: Friday, May 19, 2017 10:48 PM
> >>
> >> Pretty sure that connector is an off the shelf Amphenol part. If you
> >> can't find it, however, you can replace it with an off the shelf one
> >> that will fit in the same hole. (If your lucky, you can even re-use the
> >> pins.)
> >>
> >> The replacement will run you about $30-40 for the pair, chassis and
> >> plug. Check Mouser, etc.
> >>
> >>> On May 19, 2017, at 23:21, Bob kb8tq  wrote:
> >>>
> >>> The mating side of that 22 pin connector isn't going to be cheap. It
> >>> looks like something out of their government systems group back in the
> >> late 90's. If it is, you may have a hard time getting info on it.
> >>> I'd pop it open and see what's inside. At least that will give you an
> >>> idea if it's 20 years old or 5 years old. Knowing the era should help
> >> in the search for information.
> >>>
> >>> Bob
> >>>
>  On May 19, 2017, at 10:21 PM, Scott Armstrong  wrote:
> 
>  I acquired a Trimble 16634-10 receiver. A search of the web has
>  turned up nothing so far.
>  The unit is in a steel box built like a tank. SMA connector for
>  antenna input and a 22 pin circular connector for the I/O and power
> 
> >>
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Re: [time-nuts] Machining some aluminum help!

[Tim Shoppa]

I'm very dubious that you need a tapped 4-40 hole to be threaded any deeper
than 0.25". If you work with the machinist I'm sure you can come up with
some reasonable spec that does not require a bottoming tap and will save
you a lot of money.

I bet you went to 0.25" wall square tubing only because you want to tap the
walls for 4-40. Alternative designs can let you use much thinner material
and a very different flange on the ends, but the costs will likely move
towards welding/brazing rather than machining.

Tim N3QE

On Thu, May 18, 2017 at 12:54 PM,  wrote:

> Hi,
>
> I have a square aluminum tube 5" X 5" with a .25" wall it's 8 1/2" long.
>
> I need 20 holes in each end tapped for 4/40 and 1/2" deep.
>
> This is for a Rubidium project.
>
> The local machine shop want's $360.00
>
> Anyone have a machining setup that could do the work a bit cheaper?
>
> If not I'll give it a try myself.
>
> Please contact me off list.
>
> Thanks!
>
> Corby Dawson
>
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Re: [time-nuts] GPS seconds conversion on an Arduino

[Tim Shoppa]

Since future leap seconds aren't known very far in advance, how wise is it
to even claim to handle any possible leap second or time scale conversion,
in a firmware-controlled device that cannot download future leap second
information from the Internet?

The GPS itself presumably knows how to handle leap seconds at the moment
with possibly minor glitches.

If you can connect to the Internet, then I think you're good for maybe the
next few decades until the current concepts of "web" and "URL" and
"internet" become as hopelessly outdated as Telex addresses. I think the
URL concept probably has at least a decade left in it, and that's
considerably longer than the couple-times-a-year possibility of a leap
second, so leap second file downloads from IETF would seem to make sense if
you claim to handle such conversions.

The "future-proofing" of your time conversion is not a new issue. When I
read century-old articles about gear ratios for converting solar to
sidereal time (*) , they note that you should not try to get too many
digits of precision because they knew that the length of the solar day had
real and unpredictable variances even back then. One author notes that if
you want your gear ratio to work well for the next 100 years, you should
use the ratio appropriate for 50 years into the future, not today.

Now admittedly, microcontrollers generally don't last as long as a set of
gears :-)

Tim

On Sat, May 13, 2017 at 9:58 PM, Mark Sims  wrote:

> Converting GPS seconds to Gregorian date/time on the Arduino will be an
> arduous task.  You take GPS seconds and add it to the GPS starring epoch to
> get a Julian date.  Then add in the number of leap seconds as a fraction of
> a day to get UTC and possibly add in a time zone offset for local time.
> Don't forget to do daylight savings time conversion...  Then convert the
> result to Gregorian date/time for display.
>
> The problem is the Arduino floating point library is single precision only
> and does not have the resolution needed to handle the numbers involved.
> Doing it with integer arithmetic (long longs) opens up a whole new can of
> worms.
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Re: [time-nuts] time.gov

[Tim Shoppa]

I was observing a consistent 5-second discrepancy between real time (GPS,
WWV, and NTP sources were checked) and time.gov web page last night.

Round-trip web request/response time between me and time.gov is less than
100ms.

This morning it is working fine.

Note that whenever I drive by the Naval Observatory I try to at least
glance at my watch and compare it to the big clock too :-). Occasionally
their LED clock on Mass Ave is off.

Tim N3QE

On Thu, May 11, 2017 at 6:09 PM, Donald E. Pauly 
wrote:

> https://www.febo.com/pipermail/time-nuts/2017-May/date.html
>
> About 10 years ago, I checked my WWVB time code receiver that I built
> against time.gov and it was within 0.1 seconds.  That was as close as
> the eyeball can tell.  You report a huge error and if confirmed, you
> should complain.  I would double check against WWV since WWVB is now
> worthless for time comparison.  That webpage is supposed to be
> compensated for network delay within 0.1 second.
>
> Just now at 15:00:00 MST I checked my phone with time.gov on wireless
> versus a full size computer also on wireless.  I momentarily saw the
> phone 65 seconds ahead of the computer.  After hitting refresh and
> going off wireless and directly to my carrier, the phone matched the
> computer.  I had a witness but cannot get the problem to reappear.  I
> don't know exactly why the problem went away.  Some servers may cache
> web pages so refresh may be necessary.
>
> πθ°μΩω±√·Γλ
> WB0KVV
>
> -- Forwarded message --
> From: Jerry Hancock 
> Date: Thu, May 11, 2017 at 2:36 PM
> Subject: [time-nuts] time.gov
> To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
>
>
> I went to time.gov today as I was sitting away from my lab when a new
> watch arrived.  Finally got the 25yr watch from the company that laid
> me off a week later…
>
> Anyway, I set the seconds rollover to 00 when time.gov reset and then
> walked down to my lab and noticed the watch is now 6 seconds slow.  So
> I checked again with another computer, same problem, www.time.gov is 6
> seconds slow.  Never say this happen, usually it is right on the money
> give or take about .2 seconds.
>
> Jerry
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Re: [time-nuts] Looking for a HP-58503 display

[Tim Shoppa]

If you're looking for a modern display screen that is easy to interface to and 
drop-dead beautiful, check out the OLED modules. But on-life is extremely 
limited, often after one or two years defects become visible - not for an 
always-on application.

Tim N3QE

Sent from my VAX-11/780
> On May 9, 2017, at 4:21 PM, Chris Albertson  wrote:
> 
> I've read about people making a replacement using a large LCD graphic
> screen.   A micro controller reads the data lines going to the old display
> and draws characters on the modern screen.Not total rocket science to
> implement but still  it would easier to buy try the easy fixes first (check
> cap, transistors and such or even buy a "for parts not working " unit from
> eBay.But the only units do look nice with a new cell phone screen
> 
>> On Tue, May 9, 2017 at 12:42 PM, Gregory Beat  wrote:
>> 
>> Mark -
>> 
>> Option 001 for the HP-5803B GPSDO
>> featured a 12-character (alphanumeric) Vacuum Fluorescent Display (VFD).
>> It appears to have been a custom VFD for HP / Agilent (Colons used in time
>> display).
>> http://www.leapsecond.com/museum/hp58503a/097-58503-13-iss-1.pdf
>> 
>> Noritake Itron Corp. (Ise Electronics Corp.) of Japan invented the VFD
>> technology in 1967.  Noritake, Newhaven, Futaba, Samsung, and a Chinese
>> mfg. are the 5 major mfg.
>> Three of these companies have their North American HQ offices here in
>> Chicago area.
>> 
>> Futaba in Schaumburg
>> http://www.futaba.co.jp/en/display/vfd/lineup.html
>> 
>> Noritake Itron Company in Arlington Heights
>> https://www.noritake-elec.com/
>> 
>> Newhaven Display in Elgin
>> Company is more of an East Asian importer, but handles custom runs.
>> http://www.newhavendisplay.com/vfd-c-586.html
>> 
>> VFD do have a finite life, and darken as they age.  Samsung states 30,000
>> hours to reach it 80% level (brightness).  You stated your unit has 83,000
>> hours.
>> DOUBLE CHECK DC Power and electrolytic capacitors associated with circuit,
>> this has been known issue with commercial consumer appliances with VFD.
>> The mfg. date on your unit may have been during "bad caps" decade.
>> 
>> greg
>> w9gb
>> ==
>>> I recently got in an HP-58503B GPSDO from a local equipment liquidation
>> auction.
>>> The unit has 83,000 hours of run time.  I think it was last powered up
>> in 2013.
>>> 
>>> The display (VFD) is a bit dim and blotchy.
>>> Does anybody have a replacement display that would look better?
>>> - Mark
>> --
>> Sent from iPad Air
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> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Using 5335 frequency counter for timing

[Tim Shoppa]

Jerry, it's very different than the equipment you currently have, but there
are specialized microwave TDR's that are used to quantify and localize
impedance bumps down to the fractional inch level (which would be tens of
picoseconds). You can "see" every connector and PCB/cable transition using
these TDR's.

Tim N3QE

On Sun, May 7, 2017 at 8:52 PM, Jerry Hancock  wrote:

> I was showing my son how we could measure the difference in cable lengths
> by using the velocity of light and cable velocity factor.  I used a scope
> to measure the offset and was then thinking the 5335 could do it more
> accurately, but I was wrong, as it only reports to the nanosecond.  I
> thought I had seen somewhere where people were getting higher resolution
> using software along with the 5335, no?
>
> Thanks
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Re: [time-nuts] Frequency counter questions

[Tim Shoppa]

Jerry, for a 100MHz PIC based counter a prescaler will be necessary. But it 
will not be necessary for a 30MHz counter.

Prescalers do not have to be by divisors of 10. I recall the PIC counter input 
to be good to 50MHz so the prescaler could just be a divide by two if you need 
a 100MHz counter and it *has* to be done by a PIC.

Of course there are lots of logic families that don't need a prescaler at 
100MHz and could be used to make a frequency counter.

Most frequency counter designs out there on the net introduce an extra count or 
two due to flawed conception of gate.

Tim N3QE

Sent from my VAX-11/780

> On Apr 23, 2017, at 9:25 PM, Jerry Hancock  wrote:
> 
> For some reason I am not getting the individual emails so I apologize for not 
> replying more promptly.  I’ll have to check my profile.
> 
> As far as I can tell from the notes, and by the way, the number of notes was 
> why I was trying to move this off list, to get to .001hz I need to measure 
> over 1000 seconds.  This is ok.  Since I am looking for an average over time 
> anyway, this is not a problem.  By the way I am using a GPSDO and planned to 
> use it divided down for the gate.
> 
> The only reason I mentioned a prescaler was that there was a 12 digit counter 
> schematic on the web that looked pretty complete.  This person used a 
> prescaler and I was trying to wrap my head around how this helped with 
> resolution and I guess from the replies, that is not a practical solution 
> (using a prescaler) when you want high resolution unless I use the inverse 
> operation which I can’t remember what it is called off the top of my head.
> 
> I’ve seen some HP 12 digit counters but since I have a GPSDO and who knows 
> how many micro development boards around here, I thought I would take a run 
> at it.
> 
> So to summarize, if I limit my high resolution to 99,999,999.999hz and use a 
> gate of 1000 seconds, would that get me to .01hz?  If not, then what would 
> the possible resolution be?
> 
> Thanks for all the input, very helpful.
> 
> Jerry
> 
> 
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Re: [time-nuts] Name of integral of timing residual

[Tim Shoppa]

I looked at AN1279 and other HP Smartclock documents that were written for
the telco holdover specs, and they always put a zero axis on the frequency
offset, but I was surprised that for example fig A4 of AN1279 seems to be
suppressing the zero axis for the time error. So they seemed to be
unconcerned with the integral you speak of.

Tim N3QE


On Thu, Apr 20, 2017 at 1:17 AM, Jim Palfreyman  wrote:

> 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] TAPR TICC boxed (input protection)

[Tim Shoppa]

I have a really naive question: how can picoamp leakage parts be relevant in 
low impedance input pulse conditioning to an interval counter?

Tim N3QE

> On Apr 11, 2017, at 7:46 AM, Bob kb8tq  wrote:
> 
> Hi
> 
> 
>> On Apr 11, 2017, at 7:05 AM, Charles Steinmetz  wrote:
>> 
>> David wrote:
>> 
>>> I ended up qualifying 2N3904s based on manufacturer and lot and I
>>> think we ended up using ones from Motorola.  I wish detailed process
>>> information like National had was available from every manufacturer.
>> 
>> It is, if you ask the process engineers for it.  (From the Big Boys, that 
>> is.  These days it seems discrete devices are being fabbed by dozens of 
>> "garage" operations.  I can't speak for them, and wouldn't think of buying 
>> product from them.)
> 
> If you dig into where your simple discrete part was made, you might be 
> surprised. That’s even true of outfits you would
> consider to be a “Big Guy” from days gone by. The real answer to selection 
> today is to buy the automotive part.
> That’s about the only thing anymore that locks down the sourcing, testing, 
> and the process. If you buy a “normal” part,
> it might have been made anywhere by just about any process. Yes, that’s scary 
> and it raises a lot of questions. It is
> a change that has happened over the last decade or two without a lot of 
> publicity. 
> 
> Bob
> 
> 
>> 
>> Best regards,
>> 
>> Charles
>> 
>> 
>> 
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[time-nuts] 32768Hz oscillator using AT-cut crystal

[Tim Shoppa]

Now, this is neat, and I'm not surprised that it's manufactured by Seiko. A
32768Hz oscillator chip that uses a 16MHz-range AT-cut crystal for a
completely different temperature curve than you'd get from a tuning fork
crystal: http://www.npc.co.jp/en/news/release/2012/11/28/78/

The principle of the MM5369 lives on, almost half a century later! That was
a chip that started with a 3.579MHz colorburst crystal and made 60Hz out.
MM5369 was discontinued decades ago, NTSC is dead for several years, but
3.579MHz crystals still readily available I see.

Tim N3QE
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Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork crystal specs

[Tim Shoppa]

Interesting that someone would complain their car clock, kept at
temperature controlled 25C, runs fast.

The manufacturer would set the clock calibration, not at 25C, but at 10C
(typical winter temperature) or 40C (average of cool night and baking hot
car interior temperature in summer).

So one half of the year the average temperature is on one side of the 25C
crystal turning point hump.

And the other half of the year the average temperature is on the other side
of the 25C crystal turning point hump.

Someone who put the clock indoors, at a fixed 25C temperature, would indeed
see the clock running fast.

But someone who keeps it in the changing outdoor weather, might find it
running on time (on average) in both winter half and summer half of year.

Still impressive that it's better than 4ppm on average over summer and
winter.

Tim N3QE

On Sun, Apr 9, 2017 at 7:45 AM, Tim Shoppa <tsho...@gmail.com> wrote:

> I've had only a few different cars over the past 25 years but I've been
> impressed with how accurate their mass-market built-in clocks are,
> especially considering the wide and completely uncontrolled temperature
> range. In the winter the interior of the car gets down below freezing most
> mornings, and in the summer the interior gets way above 120F in sunlight.
>
> (Contrast the above with the time-nuttery here where folks buy double-oven
> OCXO's and then they insist that the OCXO's have to be put in temperature
> controlled environments.)
>
> I only set the car clock twice a year, at daylight savings time changes.
> Yet between daylight savings time changes, the car clock never drifts by
> more than a minute.
>
> 60 seconds in half a year is 4ppm. So I went and looked at the specs of a
> stock 32kHz crystal, for example http://www.mouser.com/
> ds/2/77/CFS-CFV-4402.pdf
>
> 1: The crystal is speced as having a turnover point of 25C. I understand
> that.
> 2: Frequency at the turnover point is speced as being +/-20ppm. OK, that's
> not bad, most of that can be compensated for with a small trimmer cap at
> the factory to the 4ppm range. Or maybe they just program in the clock
> divider at the factory appropriate to the crystal.
> 3: The temperature coefficient of the tuning fork cut around the turnover
> point seems to always be the same: -.034ppm per deg C squared. If the temp
> goes down to 5 deg C, then, the frequency changes by 14ppm. If the temp
> goes down to -5 deg C, the frequency changes by 30ppm.
>
> With that temperature coefficient, temperatures like -5C or 5C that are
> common every winter would result in a few minutes of drift every winter.
> Yet I never observe that drift.
>
> So my conclusion, is that all these car clocks must be temperature
> compensated. And they must've been doing this for several decades at this
> point.
>
> That shouldn't be too surprising - right next to the clock display on the
> dashboard is a digital thermometer. Maybe 30 or more years ago the
> temperature compensation was done by analog circuitry, but today I'm
> guessing there's a digital chip that takes the thermometer reading and
> numerically adjusts the divider word for the 32kHz oscillator to
> temperature compensate the clock digitally.
>
> Is there a way to verify my guess at the TCXO method?
>
> I'm guessing that all the better quartz wristwatches use a similar
> technology too. Maybe they have a different crystal cut that is closer to
> body temperature for the turnover point.
>
> Tim N3QE
>
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[time-nuts] Car Clock drift - the lowly 32kHz tuning fork crystal specs

[Tim Shoppa]

I've had only a few different cars over the past 25 years but I've been
impressed with how accurate their mass-market built-in clocks are,
especially considering the wide and completely uncontrolled temperature
range. In the winter the interior of the car gets down below freezing most
mornings, and in the summer the interior gets way above 120F in sunlight.

(Contrast the above with the time-nuttery here where folks buy double-oven
OCXO's and then they insist that the OCXO's have to be put in temperature
controlled environments.)

I only set the car clock twice a year, at daylight savings time changes.
Yet between daylight savings time changes, the car clock never drifts by
more than a minute.

60 seconds in half a year is 4ppm. So I went and looked at the specs of a
stock 32kHz crystal, for example
http://www.mouser.com/ds/2/77/CFS-CFV-4402.pdf

1: The crystal is speced as having a turnover point of 25C. I understand
that.
2: Frequency at the turnover point is speced as being +/-20ppm. OK, that's
not bad, most of that can be compensated for with a small trimmer cap at
the factory to the 4ppm range. Or maybe they just program in the clock
divider at the factory appropriate to the crystal.
3: The temperature coefficient of the tuning fork cut around the turnover
point seems to always be the same: -.034ppm per deg C squared. If the temp
goes down to 5 deg C, then, the frequency changes by 14ppm. If the temp
goes down to -5 deg C, the frequency changes by 30ppm.

With that temperature coefficient, temperatures like -5C or 5C that are
common every winter would result in a few minutes of drift every winter.
Yet I never observe that drift.

So my conclusion, is that all these car clocks must be temperature
compensated. And they must've been doing this for several decades at this
point.

That shouldn't be too surprising - right next to the clock display on the
dashboard is a digital thermometer. Maybe 30 or more years ago the
temperature compensation was done by analog circuitry, but today I'm
guessing there's a digital chip that takes the thermometer reading and
numerically adjusts the divider word for the 32kHz oscillator to
temperature compensate the clock digitally.

Is there a way to verify my guess at the TCXO method?

I'm guessing that all the better quartz wristwatches use a similar
technology too. Maybe they have a different crystal cut that is closer to
body temperature for the turnover point.

Tim N3QE
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Re: [time-nuts] The ultraAtomic clock for home

[Tim Shoppa]

I have been happy with the Casio Waveceptor watches. They can display UTC.

They seem to reliably set themselves between midnight and 3AM each morning
when I'm wearing them here in Maryland, more reliably than the (non-PSK)
WWVB wall clocks.

The Casio WV58A-1AVCR is a plastic LCD watch for $28 that lasts a couple
years. The face scuffs easily and the band only lasts a little more than a
year before needing replacement.

I upgraded to the Metal-body-metal-band Casio WVA-M640D-1ACR almost a year
ago and am very happy. Analog display for local time, and the LCD display
can show UTC. About $90.

Tim N3QE
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Re: [time-nuts] HP-59309A Clock counts only seconds

[Tim Shoppa]

CMOS availability has held up pretty well because of its wide voltage
range. Mouser has over eleven thousand CD4011BE's in stock:
http://www.mouser.com/ProductDetail/Texas-Instruments/CD4011BE/

I can't rule out an old logic gate dying, but I would suspect this first:
Some clocks were made or modified to be tied to external minute and/or hour
synchronization pulses and these inputs can hold and jam zeroes into the
minute and hour counters.

Tim N3QE

On Mon, Apr 3, 2017 at 7:43 PM, Jeremy Nichols  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] Antique precision timing device without electronics

[Tim Shoppa]

Morris's figure of "taking over a minute to stop oscillating" at 25Hz,
implies a Q in the ballpark of 25*60, or Q>1500, which is quite good for a
tuning fork in air (usually quoted around 1000).

Tim N3QE



On Thu, Mar 16, 2017 at 2:04 PM, Bill Hawkins  wrote:

> Hi Morris,
>
> If there's no active devices (and you'd be sure to see them, not solid
> state) where does the power to operate the motor come from? Is it the
> same contacts that drive the fork?
>
> It's amazing that there is high Q when contacts must be operated by the
> fork.
>
> Did it come with instructions for setting the weights at the end of the
> fork tines?
>
> Best regards,
> Bill Hawkins
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris
> Odell
> Sent: Thursday, March 16, 2017 4:23 AM
> To: time-nuts@febo.com
> Subject: [time-nuts] Antique precision timing device without electronics
>
> Hi all,
>
> I was recently asked to resurrect this interesting device by a colleague
> who collects antique scientific instruments. It's a "Chronoscope" made
> by the H. Tinsley company in London in the early 20th century and used
> to measure time intervals with the precision of those days. It's large
> and heavy in a polished wooden case with a top deck that hinges up to
> reveal the innards.
>
> The timing reference is a large tuning fork about 30 cm (1 foot) long
> and running at 25 cps. It's normally in a glass fronted housing (removed
> for the video) that includes a pair of hinged mechanical arms for
> starting it. It's maintained in oscillation by an electromagnet and
> contact arrangement powered from a 12V DC supply. The fork amplitude is
> controlled by a rheostat - too much and the tines impact on the magnet.
> The video frame rate makes the fork look slower than it actually is. I
> was able to extract a signal and measure the frequency with a modern GPS
> disciplined counter - it's 0.007% off its specified 25 Hz! The frequency
> is too low for my HP 5372A so I was not able to easily get an idea of
> stability or do an ADEV measurement. The fork has quite a high Q and
> takes over a minute to stop oscillating after the power is turned off.
> There's a built in higher voltage AC power supply, probably a mains
> transformer, potted in beeswax in a polished wooden box inside that is
> intended to
>   energise a large neon strobe lamp used to adjust the fork.
> Unfortunately the lamp was not with the unit and is no doubt
> irreplaceable.
>
> The 25 Hz signal is filtered by an LC network  and used to run a
> synchronous motor in the Chronoscope unit. Synchronous motors not being
> self-starting, you need to tweak a knob to get it going - there's a joke
> in there but I can't for the life of me think what it could be ?? The
> "Contact" switch and associated socket on the back controls an
> electromagnetic clutch that connects the clockwork counter mechanism to
> the motor and the contact "on" time is indicated on the dials with 10 mS
> resolution.
>
> There's not a single active device in there and after a clean and lube
> it runs very nicely from a modern 12V DC plugpack. My friend is very
> pleased with it and it will take pride of place in his collection.
>
> I'd be interested to know if any time nuts have knowledge or experience
> of this lovely instrument.
>
> A video of it is at  https://youtu.be/i5S8WS9iN_E
>
> Enjoy!
>
> Morris
>
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Re: [time-nuts] Bye-Bye Crystals

[Tim Shoppa]

With a chunk of raw crystal material and a lapidary saw, blanks can be cut.

Typical FT-243/U crystal construction technology up through the 1950's:

http://www.rfcafe.com/references/popular-electronics/after-class-Quartz-Crystals-january-1957-popular-electronics.htm

It was very common for hams to regrind crystals for other nearby
frequencies at home:
http://www.bliley.net/XTAL/docs/misc/XTAL_grinding/grinding.html

I have a large assortment of 50's/60's/early 70's FT-243 crystals and they
are uniformly crummy from a Q or frequency accuracy perspective. Sometimes
opening the holder and cleaning the electrodes and crystal helps a bit -
there's some attempt at sealing, like a rubber grommet, in some of the
FT-243 holders but mostly there's no attempt at sealing. It's possible the
rubber grommets just made things worse through outgassing.

Tim N3QE



On Mon, Mar 13, 2017 at 11:01 AM, Adrian Godwin  wrote:

> The article mentions that the business started in his father's garage.
>
> What minimal equipment would you need to make your own crystals ?
>
>
> On Mon, Mar 13, 2017 at 2:11 PM, Van Horn, David <
> david.vanh...@backcountryaccess.com> wrote:
>
> >
> > Probably true for many things.   My current design has six crystals, and
> > exactly none of them could be replaced by an oscillator module.
> > Power and space considerations mostly.
> >
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Re: [time-nuts] Coming to a drive-way near you: Optical Lattice clocks

[Tim Shoppa]

Well, I learned a new phrase. I can't wail until the
chronometric-leveling-nuts list gets started!

Tim N3QE

On Thu, Feb 23, 2017 at 3:23 PM, Poul-Henning Kamp 
wrote:

> Have we talked about this yet ?
>
> https://arxiv.org/abs/1609.06183
>
> https://arxiv.org/abs/1607.03731
>
>
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] advice

[Tim Shoppa]

So this is the Pound-Rebka experiment with lasers instead of the original Fe57 
gamma rays and Mossbauer effect?

Tim N3QE

Sent from my VAX-11/780

> On Feb 21, 2017, at 9:33 PM, Bill Byrom  wrote:
> 
> Review the theory and results in this paper:
> 
> http://science.sciencemag.org/content/329/5999/1630?variant=full-text[1]
> 
> 
> For small height changes on the surface of Earth, a clock that is higher
> by a distance ∆h runs faster by ...
> The gravitational shift corresponds to a clock shift of about 1.1 ×
> 10−16 per meter of change in height.
> --
> 
> Bill Byrom N5BB
> 
> 
> 
> 
> 
> 
> 
>> On Tue, Feb 21, 2017, at 11:13 AM, Rhoderick Beery wrote:
>> 
>> Greetings Time-Nuts!
> 
>> 
> 
>> I'm a physics theorist interested in performing an experiment
>> to measure
>> the gravitational time dilation beneath the surface of the
>> Earth. Boulby
>> Labs in the UK is 1.1 km down which would generate a time differential
>> from
> 
>> the surface on the order of 1 part in 10^15 -- not much to work with!
>> 
> 
> 
> 
> 
> Links:
> 
>  1. 
> http://science.sciencemag.org/content/329/5999/1630?variant=full-text=1_redirect_count=1=251c50aa-4576-4ddf-aa31-b39ac90299c2
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Re: [time-nuts] Vintage Frequency Measurement

[Tim Shoppa]

For those of us who have to translate between the old "cps" and the modern
"Hz", I found this handy conversion table on the web:
http://www.aqua-calc.com/convert/frequency/hertz-to-cycle-per-second

Tim N3QE

[image: Inline image 1]

On Tue, Feb 14, 2017 at 5:29 AM, Peter Vince 
wrote:

> On 14 February 2017 at 04:23, Raj  wrote:
>
> > I have a Marconi T.F. 643 C, in Megacycles !
> >
>
> Ah, a sensible, descriptive name for the unit.  Some of these modern units
> really do Hert(z) :-)
>
>  Peter
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Re: [time-nuts] Thermal effects on cables

[Tim Shoppa]

Dave, the typical spec sheet for VNA cables have a very restricted "lab
temperature" range specified. For example 23C +/- 5C.

There's a very nice graph showing effect of flexure on phase stability in
Fig 2 of this spec sheet:
https://www.gore.com/sites/g/files/ypyipe116/files/2016-07/GMCA-0224-DAT-US-MAY16_e.pdf

Funny how people always want to put the words "dielectric" and "constant"
right next to each other but we know it isn't constant :-)

Tim N3QE

On Mon, Jan 23, 2017 at 8:26 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> On 13 January 2017 at 06:52, Ole Petter Ronningen 
> wrote:
>
> > Hi, all
> >
> > The question of phase shifts in cables pops up every now and then on this
> > list - I stumbled across a good table of measured phase shifts with
> > temperature in different cable types in this paper:
> > http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_
> > PresentationWSchaefer.pdf
> > that I though would be of interest to others.
> >
> >
> I've like to know how VNA cables compare. They are expensive enough - a
> couple of cables around 600 mm long (24") for my VNA are over $5000. They
> are much larger diameter than normal cables, but much more flexible too.
> The construction is obviously very different. Since mine are designed for
> use to 26.5 GHz, the internal diameter of the outer conductor can be no
> more than a couple of mm, yet the overall cable has a diameter of about 15
> mm.
>
> Dave
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Re: [time-nuts] purpose of time of day display units

[Tim Shoppa]

http://www.washingtonpost.com/lifestyle/style/for-public-clocks-a-time-warp/2011/10/25/gIQAXOZ5jM_story.html

"If the clocks are right — on churches and in classrooms, on stores and in
bars — they tell us that things are in order. They tell us that people
are paying attention. If a clock is wrong, maybe everything else is,
too."


On Sun, Jan 22, 2017 at 1:31 AM, Ruslan Nabioullin 
wrote:

> Hi, looking at pictures of various time metrology equipment setups for
> best practices and inspiration, I have commonly seen time of day display
> unit(s) installed in racks containing processing or time transfer
> equipment, e.g., http://www.xyht.com/wp-content/uploads/2015/05/Powers_
> Master_Clock.jpg. All that these units do is merely display the time of
> day and sometimes the date, typically by means of seven segment LED
> displays, of the time code inputted to them (typically IRIG-B, I'm
> guessing).  Any ideas why such a unit is necessary when one can simply look
> at the time displayed by timing receivers and time code generators (and
> even some standards), and the interface of some fusor, defined in this
> context as a system which performs timing data fusion (by implementing a
> paper clock or a more primitive algorithm) and timekeeping, either by means
> of a direct shell, or via something like NTP?
>
> Thanks in advance,
> Ruslan
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Re: [time-nuts] purpose of time of day display units

[Tim Shoppa]

The big clocks on the walls of the control center were largely eye-candy
for visitors, but the individual clocks at each console were continuously
used by the operators for everything (there was no computer display of
time). All important technical timing was run from dedicated sequencers but
it might be "kicked off" from IRIG-derived pulses on some occasions (in my
experience it might be spec'ed to be kicked off from IRIG but in real life
it was initiated by pushbutton).

Some control centers used a second audio channel to distribute elapsed
mission time via IRIG. That wasn't exactly my kind of control center but I
got to visit them.

In decades past I worked extensively with analog multitrack telemetry and
voice recorders that would record the IRIG analog code at same time as data
and voice. On playback we would both watch pulses and carrier from IRIG on
pen charts and scopes to derive timestamps, and we would also hook up a
standard IRIG-driven clock to the recorded IRIG audio show where we were in
the playback. We had at least one special playback station that could show
IRIG time correctly through variable speed forward and reverse driven by
the IRIG audio carrier. Much later we used minicomputers with ADC's to
digitize the data, timestamp derived from IRIG audio.

Tim N3QE


On Sun, Jan 22, 2017 at 1:31 AM, Ruslan Nabioullin 
wrote:

> Hi, looking at pictures of various time metrology equipment setups for
> best practices and inspiration, I have commonly seen time of day display
> unit(s) installed in racks containing processing or time transfer
> equipment, e.g., http://www.xyht.com/wp-content/uploads/2015/05/Powers_
> Master_Clock.jpg. All that these units do is merely display the time of
> day and sometimes the date, typically by means of seven segment LED
> displays, of the time code inputted to them (typically IRIG-B, I'm
> guessing).  Any ideas why such a unit is necessary when one can simply look
> at the time displayed by timing receivers and time code generators (and
> even some standards), and the interface of some fusor, defined in this
> context as a system which performs timing data fusion (by implementing a
> paper clock or a more primitive algorithm) and timekeeping, either by means
> of a direct shell, or via something like NTP?
>
> Thanks in advance,
> Ruslan
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Re: [time-nuts] wifi with time sync

[Tim Shoppa]

Bob, I think you are pushing me in this direction, but it was my conclusion
before this discussion even began.

Most consumer WiFi devices will quiesce the WiFi chipset between major
consumer-initiated usages for battery savings, so it's not surprising to
see a good amount of random variation in ping times when done from a laptop.

Some apps that try to do timing over internet do a "wake-up call" of the
interface first, and then do the timing. I don't know if this was ever
added to ntpd but I work with all sorts of UDP applications that have to do
application-level things like wake-up calls or application-layer keepalives
to bring VPN tunnels "Back to life" (otherwise the first UDP packets are
dropped).

Tim N3QE



On Sat, Jan 14, 2017 at 2:02 PM, Bob Camp  wrote:

> Hi
>
>
> > On Jan 14, 2017, at 1:38 PM, Chris Albertson 
> wrote:
> >
> > On Sat, Jan 14, 2017 at 7:46 AM, Bob Camp  wrote:
> >
> >> Hi
> >>
> >> Ok, what I see is that every few hours, I get a “rogue delay” on a
> single
> >> ping. How
> >> would NTP help me spot a single transit with a 250 ms round trip and
> >> identify the
> >> time it occured? Keep in mind that NTP is going to throttle back to a
> very
> >> low level
> >> of “chat” quite quickly…..
> >>
> >
> > I don't understand about NTP throttling back? Yes it quickly figure out
> the
> > best poll interval to each of the configure reference clocks but that is
> a
> > good thing.
>
> Not a good thing if you want to check the link at least once a second and
> keep
> doing so for days and days. If the objective is to profile the timing
> stability of
> the WiFi link *and* catch all the stupid things that happen … you need a
> lot
> of data. There are things that happen at widely spaced intervals. Is a
> ping the
> best thing to use? Certainly not. There just aren’t a lot of other
> candidates.
> Indeed there can be such a thing as “to much data”, there is an ADEV thread
> going along about that.
>
> Bob
>
> > You like those poll intervals to be as long as possible
> >
> > It will tell you the TIME an event occurred with good accuracy.  Record
> the
> > ping delay and the ping's time of day in the file.  Then if you want to
> > compare files between different logs made on different computers you can
> > know that all the time stamps are comparable.  I assume you want to know
> > the cause so you'd have to look at logs from other devices on your
> network
> >
> > Question: do something happen every hour to cause this or is that
> something
> > happening say every 13 seconds and sets in phase with the ping interval
> > every hour?
> >
> > Audio over wifi depends on "buffering".  The data are sent in packets or
> > batches.  The device that actually plays the audio will keep as much as a
> > few seconds of data and request more when the buffer gets about 1/2
> empty.
> >  So delays over wifi are not important.   The re-timing is done on the
> > receiving end, likely using a cheap crystal.
> >
> > Audio over USB, HDMI to fiber TOSLINK is packetized as well and buffered
> > and re-clocked at the receiving end.  The difference is the size of the
> > buffer.  If it is packetized then it must be buffered and rechecked, no
> way
> > out of that.
> >
> > So yes it is "giant buffers".  The data sent does contain the format, how
> > many channels, the sample rate and so forth
>
> … but If you are playing the sound out of multiple speakers scattered
> around the
> room *and* their only link is WiFi, time sync does matter. That’s what
> started this
> thread in the first place. Milisecond sync isn’t good enough in this case.
> You need
> microsecond level sync.
>
> Bob
>
> >
> >>
> >> While this *is* getting far more into my WiFi (which I had no real
> >> intention of doing) it
> >> does apply to timing and running audio over WiFi as well. The basic
> >> transport as it
> >> runs up through the various layers is *not* very good time wise. There
> is
> >> indeed a
> >> real need for some sort of overlay to take care of that issue. I’d still
> >> love to know if
> >> this magic protocol is simply giant buffers and some sort of tagging or
> if
> >> they do
> >> something more interesting.
> >>
> >> Bob
> >>> On Jan 14, 2017, at 12:32 AM, Chris Albertson <
> albertson.ch...@gmail.com>
> >> wrote:
> >>>
> >>> On Fri, Jan 13, 2017 at 1:11 PM, Bob Camp  wrote:
> 
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Re: [time-nuts] EFOS2 MASER turns 34!

[Tim Shoppa]

Thanks, I will look on Tom's site for the manuals. The last time I looked
into this, I think all I saw were copper cavities.

But I think some sort of design that required very minimal machining, and
much more "plumbing", would be what I would need to do a homebrew maser :-).

Tim N3QE

On Tue, Jan 3, 2017 at 1:14 PM,  wrote:

> Tim,
>
> The EFOS2 uses an Aluminum cavity! So machining would be easier than
> Copper!
>
> The complete manuals with schematics are on Tom's Leapsecond.com site.
>
> Making a homebrew Maser was bandied about a few years ago on TimeNuts.
>
> Cheers,
>
> Corby
>
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Re: [time-nuts] EFOS2 MASER turns 34!

[Tim Shoppa]

Very nice report, Corby!

When I was in grad school back in the 90's, doing vacuum pump work was a
very menial task usually assigned to grad students, so naturally I became
quite familiar with it :-). Especially cleaning up messes with decrepit old
experimental systems!

I think back to those days and maintaining an already-functioning H-Maser
actually seems perfectly feasible in the long term.

The tight geometry of the copper package of a H-Maser sure seems a lot more
feasible than the other atomic clocks which are way more hi-tech stuff.
That said, machining the copper would be way beyond my ability!

I also did get to work some plasma physics experiments where we used
kettles - literally large industrial cooking kettles, with some hacked-in
brazed-shut machining for the various probes and plumbing. Maybe if there
was some way to homebrew a primitive H-Maser with that low level of
construction competence I could give it a try!

Please share more tales/pics of your H-Maser experience!

Tim N3QE

On Mon, Jan 2, 2017 at 1:18 PM,  wrote:

> Happy Birthday EFOS2 Maser!
>
> The EFOS2 active hydrogen Maser at my place just turned 34 years old!
> Pretty impressive reliability.
> It is an Oscilloquartz Maser, they are now called T4 Science.
> I know a guy in Norway that bought the refurbished EFOS3 Maser last
> year directly from T4 Science! It is 32 Years old!
> I have had the EFOS2 running here pretty much continuously since
> Sept 2007.
> I've had to refill the Hydrogen bottle 3 times.
> replaced ion pumps 4 times (requires a CLEAN vacuum pumping system)
> Had to repair one of the ion pump supplies (bad capacitor)
> Also removed original 1 transistor power oscillator that was used to
> drive the discharge providing the atomic Hydrogen.
> I replaced it with a custom class A oscillator amplifier.
> It uses an Oscilloquartz B5400 Quartz oscillator that has aged very
> little since 2007!
>
> Cheers,
>
> Corby Dawson
>
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Re: [time-nuts] Line Voltage - USA

[Tim Shoppa]

What modern loads are actually sensitive to high (say, +10 to +20%) line
voltage?

Old incandescent light bulbs were among the most sensitive loads in the
past (so much so, that 130V light bulbs were commonly available from the
industrial suppliers).

I would naively expect the modern CFL's and LED replacements to be fine
with higher line voltage because they have their own built-in switching
regulation.

A lot of modern electronic equipment with switching supplies, are just fine
at +20% line voltage and may even run cooler.

Tim N3QE

On Sun, Jan 1, 2017 at 11:49 PM, Bill Byrom  wrote:

> There are a couple of recent threads concerning the power line mains
> voltage standards. After a bit of research and thinking, I have found
> that this is a complex topic. The simple answer is:
>
>
> * The standard in the US for the past 50 years has been 120/240 V +/- 5%
>   RMS at the service entrance to the building. This is a range of
>   114/228 V to 126/252 V.
> * The load voltage could be as low as 110/220 V and as high as 125/250 V
>   and be within specifications.
>
>
> There are two voltage measurement points to consider:
>
> (1) Service voltage: This is the RMS voltage measured at the service
> entrance to the building (at the metering point).
> (2) Utilization voltage: This is the RMS voltage measured at the load.
> It might be measured at an unused socket in a power strip feeding
> several pieces of electronic equipment, for example. There are of
> course many different utilization voltages present in a home or
> business, depending on where you make the measurement.
>
>
> Most US homes and small businesses are powered by what is commonly
> called a "split-phase" 240 V feed. The final distribution system
> transformer has a 240 V center-tapped secondary. The center tap is
> grounded, and three wires are fed to the building (actually it might be
> up to around 6 houses):
> (1) Leg L1 or phase A (red wire) -- This wire will measure 120 V to the
> neutral or 240 V to Leg L2.
> (2) Neutral (white wire) -- This wire is grounded at the distribution
> system and at the service entrance to the building.
> (3) Leg L2 phase B (black wire) -- This wire will measure 120 V to the
> neutral or 240 V to Leg L1.
>
>
> Large appliances and HVAC systems are usually connected across L1-L2
> (240 V), while most sockets are on circuits either connected across L1-
> neutral (120 V) or L2-neutral (120 V).
>
>
> The voltages I have described are the current standardized values for
> the service voltage which have been in general use for about 50 years
> (120/240 V +/- 5%). I believe that the original systems installed before
> 1940 were designed for a 110/220 V nominal service voltage, but after a
> report in 1949 the nominal service voltage was increased to 117/234 V,
> as specified in ANSI C84.1-1954. After research in actual buildings, in
> the 1960's the nominal service voltage was increased again, to 120/240 V
> in the ANSI C84.1-1970 standard. The purpose is to keep the utilization
> voltage at the load above 110/220 V.
>
>
> The voltage at the service entrance should in most cases be in Range A
> (120/240V +/-5%). On each 120V leg the service voltage should therefore
> be between 114 and 126 V. The utilization voltage at the load should be
> between 110 and 125 V due to losses in building wiring.
>
>
> See details of the current specifications at:
>
> http://www.pge.com/includes/docs/pdfs/mybusiness/
> customerservice/energystatus/powerquality/voltage_tolerance.pdf
>
>
> These voltage specifications were designed for resistive loads and
> measurement of the true RMS voltage. In most electronic equipment built
> over the past 50 years, the power supply input circuitry is basically a
> rectifier connected to a smoothing capacitor. This leads to high input
> current surges during the peaks of the waveform, so that the peak
> voltage is reduced much more by the building wiring resistance than if
> the load was resistive for the same power consumption.
>
>
> So the waveform shape at different utilization locations in a building
> (with active equipment loads) may be different, so the voltage measured
> by different AC measuring instruments can differ. Many meters are full
> wave average measuring but calibrated so they only read RMS voltage
> correctly on pure sinewaves. Other meters are true RMS measuring and
> will read very close the correct RMS voltage even if the waveform is
> distorted.
> --
>
> Bill Byrom N5BB
>
>
>
>
>
> On Sun, Jan 1, 2017, at 12:16 PM, CIW308 VE6OH wrote:
>
> > Mark,
>
> >
>
> > CSA have standards for over and under voltage, Typical no more that 3%
> > over and 5% under if memory serves me.
>
> >
>
> > This might help (
>
> > http://www.safetyauthority.ca/sites/default/files/csa-
> fia3660-voltagedropcalc.pdf
> > )
>
> > The power companies here in Alberta are generally good about fixing
>
> > problems with line regulation.
>
> > There can be 

Re: [time-nuts] 1PPS users?

[Tim Shoppa]

You know, there's a reason this list is called "time-nuts" and not
"frequency-nuts" :-).

But sometimes I wonder if "phase-nuts" might be a better term.

It is so incredibly useful to put your best 1 PPS into a scope and use that
to watch for systemic effects on your second-best clock. That's why we then
end up with a third, fourth, fifth, etc. clock :-)

So many newcomer GPSDO makers seem to just do frequency lock but rarely do
they or their users know the difference.

At same time there are so many non-ntpd NTP implementations that just jump
instead of slew the clock.

Tim N3QE

On Sun, Dec 18, 2016 at 6:16 PM, Bob Stewart  wrote:

> One thing I've never really understood is who actually uses the
> high-quality 1PPS output from a GPSDO.  I have spent a lot of time, effort,
> and money on developing my GPSDO without a whole of thought to the user
> base.  It was just a quest for the best result I could obtain with a
> particular technology.  The frequency standard users was a no brainer.
> Everyone who wants a frequency standard eventually understands they need to
> get a GPSDO, or an Rb, or a Cs.  And that's all I thought I had: a good
> frequency standard.  And then Tom prodded me a bit and showed me the
> shortcomings of what I was doing, and I did something about it.  So, if an
> NTP user can get his time fix directly from a noisy receiver, who actually
> needs a time-accurate, low jitter 1PPS pulse?
> Bob - AE6RV
>  -
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Tim Shoppa]

A common misconception, is that holdover is the opposite of GPS lock.
Sometimes we might even talk about the two as if we're in one or the other.
But really the power-on state, is that we're in neither holdover or GPS
lock.

Holdover means the smartclock previously had GPS lock and had used it to
characterize the aging of the OCXO, and is maintaining the EFC
extrapolation, such that it believes it can still produce accurate time and
frequency through the GPS loss.

The state of your clock at the moment, is that it has never had GPS lock
since regaining power, it does not know what time it is, and it has not
characterized or extrapolated the aging of the OCXO. So it is definitely
not in holdover.

Tim N3QE

On Sun, Dec 18, 2016 at 8:01 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> My 58503 GPS time/frequency reference had its power disconnected a few
> times yesterday as I moved things in the lab. At the modem the status of
> the LEDs are
>
> * Power green
> * GPS lock - not lit
> * Holdover - not lit
> * Alarm - not lit.
>
> That is what the manual says will happen  when power is first applied, but
> I'm puzzled why.
>
> The SYSTEM:STATUS? shows the information at the end of this email. What I
> can't understand is why the holdover light is not lit, when clearly its not
> tracking any satellites. It seems logical to me that holdover should be on,
> when GPS lock is not, and visa versa. But that does not seem to be the
> case.
>
> Looking at the data below, the date/time is obviously wrong (01 Jan 1998),
> the height at -14.04 m  (MSL) is wrong, but latitude and longitude look
> about right, although they are certainly not exactly agreeing with Google
> maps, which show 51°39'04.1"N+0°46'36.4"E.
>
> I must be misunderstanding the purpose of these lights.
>
> I'm also a bit puzzled it has been on about 1.5 hours, and can't seem to
> find a single satellite. The antenna is fairly clear of anything else, and
> it was certainly working yesterday, with the power and GPS lock LEDs both
> lit.
>
> Any ideas what's going on?
>
> scpi > SYSTEM:STATUS?
> --- Receiver Status
> ---
>
> SYNCHRONIZATION ... [ Outputs
> Invalid ]
> SmartClock Mode ___   Reference Outputs
> ___
>Locked TFOM 9
> FFOM 3
>Recovery   1PPS TI  --
>Holdover   HOLD THR 1.000 us
> >> Power-up: GPS acquisition  Holdover Uncertainty
> 
>   Predict  --
>
> ACQUISITION .. [ GPS 1PPS
> Invalid ]
> Tracking: 0    Not Tracking: 1    Time _ +1 leap second
> pending
>PRN  El  AzUTC  12:59:16 [?] 01 Jan
> 1998
>*32  -- ---GPS 1PPS Invalid: not
> tracking
>   ANT DLY  0 ns
>   Position
> 
>   MODE Survey:  0%
> complete
>Suspended: track <4
> sats
>   INIT LAT N  51:39:03.825
>   INIT LON E   0:46:36.278
> ELEV MASK 10 deg   *attempting to track   INIT HGT  -14.04 m
> (MSL)
> HEALTH MONITOR . [
> OK ]
> Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
> OK
> scpi >
>
>
>
> 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] GALILEO online: any changes seen?

[Tim Shoppa]

David, several of your satellite count graphs show a slow upward trend
throughout this calendar year, with a bump up for the month of October,
falling back down for part of November, then another step up at the
beginning of December.

http://www.satsignal.eu/mrtg/performance_gps.php?period=year

This is particularly clear on the graph labeled "u-blox MAX-M8Q" on
"RasPi-10", showing a sharp uptick since December 1.

Could this be Galileo or hard to say?

Or maybe just leaves falling off of the trees? :-)

Tim N3QE

On Thu, Dec 15, 2016 at 10:43 AM, David J Taylor <
david-tay...@blueyonder.co.uk> wrote:

> Dear all,
> the GALILEO system is supposed to go online today (at least for initial
> operational capability). Does anybody of you has a GALILEO compatible
> receiver and sees already a difference?
>
> Best regards,
> Achim
> 
>
> Achim,
>
> I'm not sure whether the signals were turned on today, or whether they
> have been there for some time but just in a pre-operational status.
>
> I think all my receivers which /might/ be able to get Galileo need an
> update, and I've not seen any change in the number of satellites
> potentially visible according to gpsd, at least:
>
>  http://www.satsignal.eu/mrtg/performance_gps.php
>  http://www.satsignal.eu/mrtg/performance_gps.php?period=month
>  http://www.satsignal.eu/mrtg/performance_gps.php?period=year
>
> I heard that for some receivers, it was a choice of Galileo or
> GPS/GLONASS. I would be helpful if a list of Galileo receivers were
> available.  I did one mobile phone which offered Galileo - but "in a future
> update"...
>
> Cheers,
> David
> --
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv
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Re: [time-nuts] Time math libraries

[Tim Shoppa]

I have had some success with Perl DateTime CPAN module's support for leap
seconds - doing time delta math without using Unix Epoch Seconds properly
handles leap seconds.

Converting back and forth to Unix Epoch time works as well as it can (given
non uniqueness).

It also supports the concept of a "floating timezone" which never takes
into account leap seconds.

Tim N3QE

On Mon, Dec 12, 2016 at 1:45 PM, Eric Scace  wrote:

>(Apologies if this question has been addressed before. Archive search
> is rather cumbersome on a month-by-month basis.)
>
>Few people will be surprised to learn that MS Excel does not account
> for leap seconds when doing time math. See below for an example. This is
> just an example of many instances of programming failures.
>
>Are there good time math software libraries (e.g., Java, C++/C#, etc)
> that will do time math correctly for the chosen time scale?
>
>Thanks.
>
> — Eric
>
>
> 2016 Dec 31 Sat 23:59:57
> 2016 Dec 31 Sat 23:59:58
> 2016 Dec 31 Sat 23:59:59
> 2017 Jan 01 Sun 00:00:00
> 2017 Jan 01 Sun 00:00:01
> 2017 Jan 01 Sun 00:00:02
>
>
> My machine is on EST right now. Is it a time zone question?
>
> 2016 Dec 31 Sat 18:59:57
> 2016 Dec 31 Sat 18:59:58
> 2016 Dec 31 Sat 18:59:59
> 2016 Dec 31 Sat 19:00:00
> 2016 Dec 31 Sat 19:00:01
> 2016 Dec 31 Sat 19:00:02
>
> Nope!
>
> What about past leap seconds?
>
> 2015 Jun 30 Tue 23:59:57
> 2015 Jun 30 Tue 23:59:58
> 2015 Jun 30 Tue 23:59:59
> 2015 Jul 01 Wed 00:00:00
> 2015 Jul 01 Wed 00:00:01
> 2015 Jul 01 Wed 00:00:02
>
> Also fail!
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Re: [time-nuts] UCCM GPSDO

[Tim Shoppa]

I was trying to guess what acronym (or backronym) UCCM might stand for.
Then I did an E-bay search and found all the PC boards with "94V-0" in
their part numbers for sale E-bay. Ha! Literally thousands of hits.

Tim N3QE

On Mon, Dec 5, 2016 at 7:42 AM, Bob Camp  wrote:

> Hi
>
> I’d bet it’s an inventory label put on by their customer. If so a good bet
> would be something
> like China Unicom.
>
> Bob
>
> > On Dec 4, 2016, at 5:50 PM, Larry McDavid  wrote:
> >
> > Does anyone know the origin of the "UCCM" designation for the Trimble
> GPSDO boards recently popular here?
> >
> > Is "UCCM" a valid model number, is it an acronym or is it something else?
> >
> > I've packaged several of these Trimble boards and I've seen about four
> others, none of which was marked "UCCM." I've seen one on-line picture of a
> packaged board that shows a separate label with "UCCM" marked.
> >
> > GPSCon already supports these "UCCM" boards and the next release of Lady
> Heather is expected to support them also, so there is some acceptance of
> this "UCCM" designation. But, what is the origin of this term and is it
> valid?
> >
> > --
> > Best wishes,
> >
> > Larry McDavid W6FUB
> > Anaheim, California  (SE of Los Angeles, near Disneyland)
> > ___
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Re: [time-nuts] Switching regulator replacement for 7805

[Tim Shoppa]

Attila - I certainly do not differentiate between "ferrite bead" and "single 
turn toroidal choke".

I think the SMT inductor manufacturers think of them in the same bucket too.

what I think of as a "ferrite core for winding a multi turn inductor on", is 
invariably listed as a "ferrite bead" in the catalog these days.

Most of my switchers run in the very low MHz and I like to have at least 
several hundred ohms at that frequency before a bus or wiring run. This often 
means ten or more turns. 

Tim N3QE

Sent from my iPhone

> On Dec 5, 2016, at 7:24 AM, Attila Kinali  wrote:
> 
> On Sun, 4 Dec 2016 17:07:53 -0800
> jimlux  wrote:
> 
>>> Wouldn't it be better to use a ferrite bead instead, for this application?
>>> The much lower series capacitance and thus higher self-resonance frequency
>>> should help damping the spurs.
>>> 
>> sure, if you can get enough L.  The other thing is that SMD inductors 
>> can be placed by machine, which isn't necessarily the case with ferrite 
>> beads (depending on how you do them).
> 
> A BLM18 gets you into the order of 300Ω @ 100MHz, which is about
> the equivalent of about 480nH. Using a lower current version gets
> you into the 1kΩ @ 100MHz range (~1.6µH). Shouldn't that be enough
> inductance?
> 
> 
> Combined with some 10µF of capacitance and you already get ~15dB @ 1MHz
> for a simple LC-lowpass. For additional filtering, add something like an
> NFM18PS105 and you  get good filtering up to ~100MHz.
> 
> 
>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] Switching regulator 12 > 4 V (3.3)

[Tim Shoppa]

I use the LM2574 for a lot of one-off applications the past decade or more.
For a 4V application you would start with LM2574-ADJ. It is available in
8-pin DIP, although the surface mount part is just as amenable to
dead-bugging, and does 0.5 amp no problem and runs perfectly cool. It does
not take (by modern standards) the smallest switching inductors and I
always do additional LC filtering at both input and output, so in terms of
"board space" this is quite a hog compared to more modern higher frequency
switchers.

Tim N3QE

On Sun, Dec 4, 2016 at 2:46 PM, KA2WEU--- via time-nuts 
wrote:

> Who has a good recommendation for a switching power supply circuit, 12V DC
> in, 4 V/ 500mA out , Exactly 3.3 for IC voltage.
>
> 73 de Ulrich
>
>
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Re: [time-nuts] Audio format with embedded timestamps?

[Tim Shoppa]

Thank you Chris! The clue in to "BWF" was able to let me Google up some
additional information that taught me more about BWF support in software
like Audacity, and then I found the proposals for BWF and label support in
Audacity with some source code and other tools:

http://wiki.audacityteam.org/wiki/Importing_Timestamp_Information

This appears to be on the development edge of Audacity rather than well
supported.

I have some long (24 hour) WAV files and will see if I can come to any
determination about the offset and spread of the sampling rate. e.g. if the
sampling rate nominally 44100, how precise is that in my PC's hardware? I
would bet this is tied to a crystal in the audio section of the sound card
and thus completely independent of any ntpd stabilatization being done to
the system clock.

I recall that 10ppm over 24 hours works out to 1 second. So if the sound
card crystal is good to 10ppm, that's about a second of drift after a day,
and that's not too horribly incompatible with the 1 second timestamp
resolution at the start of the BWF.

Tim N3QE

On Fri, Dec 2, 2016 at 12:20 PM, Chris Caudle <ch...@chriscaudle.org> wrote:

> On Thu, December 1, 2016 8:19 am, Tim Shoppa wrote:
> > Is there a common digital audio format that embeds in the digital
> > stream, a timestamp marker of real-world-clock-time that the
> > audio was recorded at?
> >
> > At my "day job" we have many digital "system of record" phone and radio
> > recording systems. The best they do, is to timestamp the filenames they
> > generate with the start time.
>
> You mention timestamping files, and also digital stream.  Are you looking
> for a transport protocol, or a file format?
>
> For a file format, Broadcast WAV described in EBU tech report 3285 has a
> field for origination time, with a resolution of 1 second, and a time
> reference which as I understand is the location of the first sample
> referred to the previous midnight given in sample position as a 64 bit
> number.
> Presumably this give some ambiguity of the location of the ending samples
> based on the accuracy of the sample clock originally used to capture the
> samples.
>
> If you need transport time stamps, then the audio-over-IP protocols use
> PTP as the reference clock, so you get explicit description of the audio
> sample location referenced to the PTP epoch.
>
> --
> Chris Caudle
>
>
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Re: [time-nuts] Is there any Ubuntu/Linux Software for the Z3801A?

[Tim Shoppa]

The stock ntpd has worked with HP Smartclocks for about two decades now. It
is the "GPS_HP" module. The documentation mostly refers to the HP58503A but
for all ntpd purposes, the Z3801A is the same except for different default
baud rates and serial parameters.
https://www.eecis.udel.edu/mills/public_html/ntp/html/drivers/driver26.html

ntpd is not point-and-drool "watch the satellites move individually in real
time via graphics" software. ntpd is "turn it on and leave it" software.
Logging via standard ntpd logfiles can produce some good long-term EFC
statistics but again it is not point-and-drool stuff.

Tim N3QE

On Thu, Dec 1, 2016 at 2:22 PM, Mark Sims  wrote:

> There soon will be...  Lady Heather 5.0 works on Windows/Linux/macOS and
> can talk to the Z38xx boxes.
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[time-nuts] Audio format with embedded timestamps?

[Tim Shoppa]

I think I have asked this question at least once here in past years but I
don't remember coming away with a satisfying answer.

Is there a common digital audio format that embeds in the digital stream, a
timestamp marker of real-world-clock-time that the audio was recorded at?

At my "day job" we have many digital "system of record" phone and radio
recording systems. The best they do, is to timestamp the filenames they
generate with the start time.

In decades past at work we had multitrack audio recorders doing this, that
recorded on an independent audio track the IRIG timecode already
distributed throughout the control center. This was really spiffy because
we had a playback station that could display the IRIG timecode even under
fast forward and rewind. I suppose I could do the same with a multitrack
WAV or other common audio format file but I don't know of any software that
would support the nifty IRIG display functionality.

I know that in the TV/video editing world, they have long used SMPTE and
derivative timecodes embedded in the video signal, and I'm guessing (been a
long time since I worked in the video editing field) that modern video
editing formats have progressed the SMPTE functionality.

Tim N3QE
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Re: [time-nuts] Question about AD9832 "I out Full Scale" (what does it mean?)

[Tim Shoppa]

Bruce, I assume you are talking about Figure 12 of UG-313.

If an LCD scope is not in single shot mode it will show a composite of many
cycles which will hide the stairsteps (especially if the frequency control
word is not a nice round binary number) in the fuzz.

I think the 0.1uF capacitor on IOUT on the evaluation board also helps roll
off the stairsteps.

Tim N3QE

On Thu, Nov 17, 2016 at 11:49 PM, Bruce Griffiths <
bruce.griffi...@xtra.co.nz> wrote:

> With no internal PLL to generate a higher internal frequency than the
> 25MHz MCLK, that 1MHz waveform looks a bit too smooth for an unfiltered
> 1MHz output.
> Bruce
>
> On Friday, 18 November 2016 5:12 PM, Richard (Rick) Karlquist <
> rich...@karlquist.com> wrote:
>
>
>  Trying to figure out what "Iout Full Scale" means on the AD9832.
> Some time nuts may have used this one.
>
> On page 7 of this doc:
>
> http://www.analog.com/media/en/technical-documentation/
> user-guides/UG-313.pdf
>
> It shows the AD9832 output as 572 mV peak to peak
> across 300 ohms.  This works out to 1.9 mA peak to
> peak current through the resistor.  But Rset on the
> board is 3.9K, which is supposed to give a value
> for so-called "Iout Full Scale" of 3.878 mA.
>
> I would have thought (just guessing) that peak to
> peak output current would be equal to Iout Full
> Scale, but it appears to be only half of that.
>
> Can anyone clarify this?
>
> Rick
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Re: [time-nuts] Thermal impact on OCXO

[Tim Shoppa]

Lars,

I've broadly understood the aging in the first days to month as being
dominated by "bake-out". It's well fit with a logarithmic curve but the
effect is so large in the first weeks that it hides the true long term
aging (which could well have a different direction).

Tim N3QE

On Wed, Nov 16, 2016 at 2:41 PM, Lars Walenius 
wrote:

> FWIW. Between 2001 and 2011 I run a 5MHz OCXO (in a box). It is a 2x3inch
> type without EFC marked OFC MC834X4-009W with date code 97. Probably it was
> from some base station testing and it had been sitting in my shelf since
> 98. The OCXO were battery backed but at two occasions (2004 and 2007) we
> had power fails that drained the battery as can be seen in the graph.
>
> Just out of curiosity I yesterday put just the first thirty days (like in
> the pdf mentioned below) and let Excel calculate the logarithmic function.
> If I extrapolate that to 10 years it seems that the drift would be
> 6E-13/day but as can be seen in the aging graph it was more like ten times
> higher.
>
> Some days ago I started the OCXO again after it had been on the shelf for
> more than 4 years. Enclosed is a graph for the first 7 days. After six and
> half days it seems to be a jump of about 1.5E-10 and as I have no
> indication of anything else I believe it is from the OCXO.
>
> /Lars
>
> >On Mon, Nov 7, 2016 at 10:34 AM, Scott Stobbe 
> >wrote:
>
> > Here is a sample data point taken from http://tycho.usno.navy.mil/ptt
> > i/1987papers/Vol%2019_16.pdf; the first that showed up on a google
> search.
> >
> >  Year   Aging [PPB]  dF/dt [PPT/Day]
> > 1   180.51   63.884
> > 2   196.6531.93
> > 5  218   12.769
> > 9   231.69   7.0934
> >10   234.156.384
> >25255.5   2.5535
> >
> > If you have a set of coefficients you believe to be representative of
> your
> > OCXO, we can give those a go.
> >
> >
>
>
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Re: [time-nuts] Secondary phase noise standard & FE405

[Tim Shoppa]

Some AD DDS app notes give examples of spurs and choosing nearby (but not
exactly on freq) numbers that are much less bad for spurs - or at least
that move the spurs outside the cleanup filters/loops. I don't know of a
general example or even code that does this in a general way.

One paper I like on the subject is this:
http://ttcla.org/vsreinhardt/DDS%20spur%20reduction%20techniques.pdf

P.S. I just like saying "Wheatley Jitter Injector". Not for those who are
embarrassed easily... Almost as good as "Wankel Rotary Engine".

One of

On Sat, Nov 12, 2016 at 8:13 PM, Hal Murray  wrote:

>
> kb...@n1k.org said:
> > Yes, the FE-405 uses a DDS and a cleanup. Inside the cleanup loop the DDS
> > spurs come  straight through. Since the FE-405 compensates for all sorts
> of
> > things, the DDS moves around a lot. Even a one bit change on a DDS will
> move
> > spurs around. With an ever changing  DDS, you have an ever changing
> forest
> > of “stuff” on the output.
>
> Is there a web page or such telling me where the spurs will be on a DDS
> for a
> particular constant?
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
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Re: [time-nuts] Thinking outside the box a super reference

[Tim Shoppa]

Zero. But the answer is also zero for a Rb or Cs cell!


On Thu, Nov 3, 2016 at 8:59 PM, Bob Camp <kb...@n1k.org> wrote:

> Hi
>
> Ok, how many full performance Hydrogen Masers can you build (size is not
> an issue) and
> deliver for < $10,000 (2X Bert’s number) ?
>
> Bob
>
> > On Nov 3, 2016, at 8:55 PM, Tim Shoppa <tsho...@gmail.com> wrote:
> >
> > It would obviously be larger than a homebrew Cs, but why not a homebrew
> > Hydrogen Maser Frequency standard?
> >
> > The commercial Cs units always seemed objects of pure miniaturized
> hi-tech
> > materials science magic, while the Hydrogen Masers I've seen seem much
> > larger-scale\ and more a matter of vacuum plumbing. Obviously the
> materials
> > cost for the copper microwave cavity will be very large, and I'm sure
> > Teflon-coating a quartz chamber is an art, but the pumps and magnets are
> > very familiar from my years in grad school working with plasma kettles
> and
> > mass spectrometers.
> >
> > Tim N3QE
> >
> >
> >
> >
> >
> > On Thu, Nov 3, 2016 at 4:07 PM, Bert Kehren via time-nuts <
> > time-nuts@febo.com> wrote:
> >
> >>
> >> Over the past there has been talk about building from  scratch high
> >> performance references. I think consensus was that it is out of  reach.
> In
> >> the mean
> >> time Corby is reworking an active maser which takes a lot of  know how.
> But
> >> let us look at his work on the super HP5065. It is able to  outperform a
> >> passive maser in the below 100 second range! Long term a proper  GPSDO
> >> should
> >> be possible to step in. We are working on it including pressure and
> >> temperature control. To make full use of it you also need to have the
> >> capability
> >> to monitor, record and analyze on a continuous basis preferably with out
> >> tying  up expensive equipment. We have the pieces in place and looking
> >> forward
> >> of  combining all the pieces and compare with Corby’s active Maser. We
> are
> >> back to  the GPSDO after being distracted by Tbolt performance. A third
> >> party
> >> is working  combining the GPSDO data stream with the data from the unit
> >> that
> >> generates  frequency, pressure and temperature data along with time to a
> >> USB stick, while  also be able to monitor with a PC.
> >> I know it is considered by some heresy but our lack of a  Maser and in
> >> Juerg
> >> ’s case no access to one, we try to overcome it with a GPSDO  tailored
> for
> >> Rb and Cs and control our Cs’s C field .
> >> There was a time that I did have a HP5065A but got rid of  it when I got
> >> some Cs’s. My best counter was A HP5345 and even with a Tracor 527  1
> >> second
> >> performance was not an issue. That changed when Corby introduced me to
> >> time
> >> nuts and frankly it was the first  time I learned about ADEV. But the
> >> HP5065A was gone. Now I have a cell  that Corby has plotted and time
> >> permitting
> >> may become a project.
> >> Let me get to the real issue. There are not enough  HP5065A’s out there
> and
> >> not affordable for all time nuts. Most are being kept  and are not for
> >> sale. But if a combined effort by many time nuts it MAY be  possible to
> >> recreate
> >> the guts of the HP5065A. The key word is MAY. 200 time nuts  be willing
> to
> >> invest $ 5000 each may get us there. The market does not justify  such
> an
> >> effort but time nuts keep bringing up discussions. All the other ideas
> >> kicked
> >> around in the past will cost more. There are some among us that know
> what
> >> it cost and who can make the key elements like lamps, cells, filters
> etc.
> >> Just a  thought outside the box and hopefully may turn in to a limited
> >> constructive  dialog. We will continue on our path, which include
> >> FRK/M100, HP5065
> >> and  Cs.
> >> We would not be capable to contribute technically on the  physics
> package
> >> but I would be willing to contribute financially and with  monitoring
> >> equipment even if I would not be around when finished.
> >> Bert Kehren
> >> ___
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> >> To unsubscribe, go to https://www.febo.com/cgi-bin/
> >> mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >>
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Re: [time-nuts] Thinking outside the box a super reference

[Tim Shoppa]

It would obviously be larger than a homebrew Cs, but why not a homebrew
Hydrogen Maser Frequency standard?

The commercial Cs units always seemed objects of pure miniaturized hi-tech
materials science magic, while the Hydrogen Masers I've seen seem much
larger-scale\ and more a matter of vacuum plumbing. Obviously the materials
cost for the copper microwave cavity will be very large, and I'm sure
Teflon-coating a quartz chamber is an art, but the pumps and magnets are
very familiar from my years in grad school working with plasma kettles and
mass spectrometers.

Tim N3QE





On Thu, Nov 3, 2016 at 4:07 PM, Bert Kehren via time-nuts <
time-nuts@febo.com> wrote:

>
> Over the past there has been talk about building from  scratch high
> performance references. I think consensus was that it is out of  reach. In
> the mean
> time Corby is reworking an active maser which takes a lot of  know how. But
> let us look at his work on the super HP5065. It is able to  outperform a
> passive maser in the below 100 second range! Long term a proper  GPSDO
> should
> be possible to step in. We are working on it including pressure and
> temperature control. To make full use of it you also need to have the
> capability
> to monitor, record and analyze on a continuous basis preferably with out
> tying  up expensive equipment. We have the pieces in place and looking
> forward
> of  combining all the pieces and compare with Corby’s active Maser. We are
> back to  the GPSDO after being distracted by Tbolt performance. A third
> party
> is working  combining the GPSDO data stream with the data from the unit
> that
> generates  frequency, pressure and temperature data along with time to a
> USB stick, while  also be able to monitor with a PC.
> I know it is considered by some heresy but our lack of a  Maser and in
> Juerg
> ’s case no access to one, we try to overcome it with a GPSDO  tailored for
> Rb and Cs and control our Cs’s C field .
> There was a time that I did have a HP5065A but got rid of  it when I got
> some Cs’s. My best counter was A HP5345 and even with a Tracor 527  1
> second
> performance was not an issue. That changed when Corby introduced me to
> time
> nuts and frankly it was the first  time I learned about ADEV. But the
> HP5065A was gone. Now I have a cell  that Corby has plotted and time
> permitting
> may become a project.
> Let me get to the real issue. There are not enough  HP5065A’s out there and
> not affordable for all time nuts. Most are being kept  and are not for
> sale. But if a combined effort by many time nuts it MAY be  possible to
> recreate
> the guts of the HP5065A. The key word is MAY. 200 time nuts  be willing to
> invest $ 5000 each may get us there. The market does not justify  such an
> effort but time nuts keep bringing up discussions. All the other ideas
> kicked
> around in the past will cost more. There are some among us that know what
> it cost and who can make the key elements like lamps, cells, filters etc.
> Just a  thought outside the box and hopefully may turn in to a limited
> constructive  dialog. We will continue on our path, which include
> FRK/M100, HP5065
> and  Cs.
> We would not be capable to contribute technically on the  physics package
> but I would be willing to contribute financially and with  monitoring
> equipment even if I would not be around when finished.
> Bert Kehren
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Re: [time-nuts] Man with too many clocks.

[Tim Shoppa]

Well, which 1PPS is the trigger? Is it from a "bare GPS"?

Even the GPS timing units will have the (un-sawtooth-corrected) PPS phase
make jumps by 20ns to 40ns peak-to-peak and that's a significant portion of
the 100ns  period of your 10MHz.

Typical unsawtooth-corrected PPS phase jumps:
http://www.leapsecond.com/pages/m12/sawtooth.htm

Tim N3QE



On Thu, Nov 3, 2016 at 9:22 AM, Peter Reilley 
wrote:

> I am using the 1 PPS for the trigger.
>
> Pete.
>
>
> On 11/3/2016 8:59 AM, Antonio A. S. Magalhaes wrote:
>
>>
>> Pete,
>>
>> Tell us about your trigger: where is it?
>>
>> Regards,
>>
>> Antonio/CT1TE
>>
>> ---
>>
>> A 2016-11-03 12:20, Peter Reilley escreveu:
>>
>> I am the proverbial man with too many clocks and I don't know what time
>>> it is.
>>> To correct this situation I have decided to calibrate everything.
>>>
>>> I have a HP 5370B, a HP 6370A, and a HP 5328A all with the TCXO option.
>>>  I also
>>> have some TCXO modules.   I figured that I would calibrate them against
>>> my Trimble
>>> Resolution T GPS receiver.
>>>
>>> I put the 1 PPS signal in one channel of my scope and one of the 10 MHz
>>> TCXO
>>> signals in the other channel and look at the phase relationship. The
>>> TCXO's are
>>> already close enough that I should not be out by more than a fraction of
>>> a waveform.
>>> I understand that I have to deal with the 1 PPS without sawtooth
>>> correction.
>>>
>>> I expected to see the 10 MHz signal bounce around but not move more than
>>> 1/2
>>> of a wave length.   Instead I see the 10 MHz waveform appear steady for
>>> a few seconds
>>> then jump a significant portion of the wave.   The jump is too much to
>>> be confident
>>> that I have not slipped one cycle.
>>>
>>> Can I do what I am trying to do or am I missing something?
>>>
>>> Pete.
>>>
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>>>
>>
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Re: [time-nuts] eLORAN on the air for 30 days

[Tim Shoppa]

I'm all for a diversity of systems - putting all our eggs in the GPS basket
seems unwise (and I maintain WWV receivers hooked to NTP at home!)

That said, what kind of demonstration can they do with a single LORAN site?
Or is "Wildwood" a complex with both a primary and a secondary at a short
demonstration baseline?

Tim N3QE


On Tue, Oct 25, 2016 at 10:33 AM, paul swed  wrote:

> Bob
> The system works and they are using the system for various demonstrations
> to government types. It is indeed Washingtons speed to resolution thats
> taking the time.
> So my crystal ball says nothing at all on what and when.
> But that said the fact that its on for a month lets me check some
> references.
> Regards
> Paul
> WB8TSL
>
> On Tue, Oct 25, 2016 at 7:33 AM, Bob Camp  wrote:
>
> > Hi
> >
> > Has there been any indication of just what they eventually will be doing?
> > Is this a never ending series of experiments or do they now have plans
> > to put something more perminanalt on the air?
> >
> > Bob
> >
> > > On Oct 24, 2016, at 3:23 PM, paul swed  wrote:
> > >
> > > The Wildwood, NJ eLoran transmitter will be continuously broadcasting
> > from
> > > 0900 (EST) on 21 October 2016 through 1200 (EST) on 22 November 2016.
> > > Wildwood will be broadcasting as 8970 Master and Secondary most of the
> > time
> > > but occasionally may operate at other rates.
> > >
> > > Regards
> > > Paul
> > > WB8TSL
> > > ___
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Re: [time-nuts] Has anybody checked this? GPSDO in kit

[Tim Shoppa]

I've been very impressed by the LED/VFD car clocks that come built into
cars for the past 20 years. They have to work in temperature extremes from
below zero to way above 120F when parked in the sun on a hot day. And every
six months at DST time when it's time to reset them, I find they are never
off more than a minute. This leads me to believe, they must have some sort
of temperature compensation (I'm guessing a lookup table or maybe just a
simple few-parameter formula to adjust divide-down clock based on cheap
temperature sensor) built in.

Tim N3QE

On Sat, Oct 22, 2016 at 10:52 PM, Mark Sims  wrote:

> Yep,  I recently sorted through a bag of 100 crystals from China ($10,
> shipped) looking for a "good" one.  They were ALL good...  a complete waste
> of time.  I was rather amazed at their consistency and performance for a 10
> cent part.
>
> Last year I bought an alarm clock / game from China (looks like 7 sticks
> of dynamite with an ominous circuit board / LED display strapped to it).
> It uses a 40 pin (AVR?) processor driven by a 16 MHz processor crystal.  I
> have not set it in over a year and it is still within a few seconds.  I
> suspect they measure the frequency and have a calibration tweak stored in
> EEPROM... but that seems excessive work for a $20 toy.  I highly doubt they
> go as far as doing temperature compensation.  Maybe they characterized a
> bucket of XTALs and use a generic compensation factor?
>
> --
>
> >  Yes, you can build gear to do temperature runs on crystals and sort
> bags full of them.
> It’s likely that your whole bag of 5,000 came from the same bar and your
> net result will all look a lot alike…..
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Re: [time-nuts] Has anybody checked this? GPSDO in kit

[Tim Shoppa]

I just went and visited their website, and see they also offer a "kit OCXO"
from mostly through-hole parts and PCB. The OCXO insulation box is made out
of PCB, the thermostat is simply a jellybean TO92 transistor, and the 27MHz
crystal is an AT-cut being operated around 45C, so nothing awful
time-nutty, but still pretty neat that it's a kit. Details at

http://qrp-labs.com/images/ocxokit/ocxosynth_assembly.pdf

show that it walks about 14ppm during warmup and then might be good to a
ppm or so.

Tim N3QE

On Sat, Oct 22, 2016 at 10:02 AM, Giuseppe Marullo 
wrote:

> Hello,
>
> I know, I know it is not supposed to be high end stuff(timenutted), but I
> was looking for a GPS clock and noticed that this could be a cheap GPSDO
> too:
>
> http://qrp-labs.com/progrock.html
>
> It has a OCXO option, a box, a display(customizable), a GPS and could be
> probably fitted with a Raspberry Zero for a cheap NTP server too.
>
> Any advice?
> Sorry if this has been already discussed here, didn't find any reference
> in the ML.
>
> Could it be compared to a Thunderbolt GPSO in terms of performance, how
> worse it could be?
>
> I just need a clean/self-calibrating  10MHz reference to tune HF radios
> ...seems good enough for the price.
>
> Giuseppe Marullo
> IW2JWW - JN45RQ
>
>
>
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[time-nuts] MM5314 remote setting

[Tim Shoppa]

This long thread reminded me of a technology that my employer used from the 
1970's till just a few years ago.

Our system had hundreds of HH:MM LED clocks for the public and we opened in the 
70's so of course they were digital clocks.

I had always imagined that there was some fancy electronics in the LED clocks 
because they always seemed to be well synchronized.

I was surprised during their decommissioning a few years ago, to find that the 
clock modules were a very simple 60Hz driven LED clock chip with the remote 
synchronization done by jam loading hour pulses and day pulses via audio tones 
decoded with twin-T audio filters. Our in-house telco system distributed the 
audio tones by what was effectively a systemwide PA channel. The audio tones 
went out in the second preceding the hour. Simple steering diodes were used to 
double-count at 120 Hz if the clock was running slow at the hour pulse, and to 
hold off 60Hz clock pulses if the clock was running fast or on time at the hour 
pulse. The diodes decoded the multiplexed digits not with latches, but by 
simply charging RC circuits. And the whole clock was just reset to 12am every 
night by briefly dropping power. 

The clocks were replaced by LCD screen displays that for a while showed the 
time but due to synchronization difficulties the clock display on the LCD 
display has been turned off.

Ironically for both the old clocks and new signs, they were only ever displayed 
for the public. Train operators can never see a system clock, and station 
managers usually brought their own clock in because they cannot see the clock 
on the front of their kiosk.

Tim N3QE

Sent from my iPhone

> On Oct 19, 2016, at 11:32 PM, Lee - N2LEE via time-nuts  
> wrote:
> 
> Tom nailed the issue.
> 
> First problem is I was native in thinking “Oh this will be easy to interface 
> to the NTP or GPS”.  WRONG  :) 
> But the good news I am learning a lot about accurate time from you guys.
> 
> The second issue is Tom is right. This is a cheap jumbo clock that at the 
> heart uses a Holtek HT48R30A
> 8 bit processor. Everything is contained in the chip except the 32khz crystal 
> and led drivers.
> 
> http://pdf1.alldatasheet.com/datasheet-pdf/view/82435/HOLTEK/HT48R30A.html
> 
> This is certainly not the most sophisticated clock chip available.
> 
> My original idea was to hijack the timing signal and replace it with 
> something more accurate. But the more info
> you guys share the more I see there are a couple of ways to do this. 
> Obviously the easiest might be to just replace the
> crystal with a TCXO and hope for the best. But my guess as soon as it is off 
> by one second from my other sources I will
> be back into tearing it apart again. LOL
> 
> A lot of my other clocks are 6 digit NTP POE clocks so they are not GPS 
> accurate but I would at like them to all agree.
> 
> Lee - N2LEE
> 
> 
> 
> Right, but that trick only works with analog stepper motor clocks. OP has a 
> "big digital clock" with 8-bit cpu and 32 kHz xtal. He didn't mention the 
> make/model of digital clock but in my experience very few commodity clocks 
> actually accept a 1PPS input. These clocks use 32 kHz:
> 
> 1) to drive the MCU which computes day / date / hh:mm:ss, or manages alarms
> 2) to maintain timekeeping
> 3) to multiplex digits of the LED / LCD display (e.g., at 128 to 1024 Hz)
> 4) to create the short bipolar stepper motor pulse (e.g., 1/32 kHz * 512 = 
> 1/64 s = 15.6 ms).
> 5) to create the sound for the alarm/buzzer (some PWM based on 32 kHz)
> 
> The problem is that all these functions are usually integrated into one chip 
> or even raw die/epoxy as in COB (Chip On Board). When hacking these sort of 
> clocks it is often impossible to separate 32 kHz frequency features from the 
> 1 Hz timing feature.
> 
> So when your goal is to improve timekeeping accuracy in these self-contained 
> digital clocks it's usually easier and less invasive to make the clock use 
> your precise 32 kHz signal instead of its own cheap xtal. You almost always 
> have access to the xtal, but rarely access inside the MCU.
> 
> Note that you don't even need to unsolder the xtal -- you can "jam" the 
> existing signal with an external 32 kHz sine or square wave applied to the XI 
> pin (xtal in) of the MCU. Your external GPSDO/32kHz signal will "pull" the 
> cheap xtal for free. Best yet, if your external signal goes away the clock 
> keeps running using its own xtal without skipping a beat, like getting 
> hold-over for free.
> 
> For a "no solder" or "no wires" solution, I have also tried to acoustically 
> discipline a tuning fork xtal with an GPS-based 32 kHz signal and ultrasonic 
> transducer. Poor results. I think I needed better coupling between the 
> transducer and the xtal tuning fork. But in theory it should work. Plus it 
> would keep small mammals and insects away from your clock.
> 
> /tvb
> 
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Re: [time-nuts] Atomic Watch

[Tim Shoppa]

If I saw a chess playing machine that had a bunch of gears and levers, AND
A LITTLE HUMAN INSIDE, and the proprietor was bragging about how well the
human had been trained relative to the military, I would spend all my time
wondering how much of the work the human was doing. Even if the combination
played simply awful chess.

Tim N3QE

On Mon, Oct 17, 2016 at 9:45 PM, Jim Palfreyman  wrote:

> 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] leontp offset?

[Tim Shoppa]

Check the Arbiter for anomalous "Cable Delay" or "Clock Offset" settings.
Maybe they accidentally got set to 999ns instead of zero.

Page 38 in this manual:
http://www.arbiter.com/files/product-attachments/1084_manual.pdf

Tim N3QE

On Fri, Oct 14, 2016 at 8:31 PM, gmx tallahassee 
wrote:

> Hi all,
>
> I'm checking out the leontp ntp time server (leontp.com).  After a week of
> use I am getting the following ntp -q output:
>
> $ ntpq -pn
>  remote   refid  st t when poll reach   delay   offset
> jitter
> 
> ==
> *172.17.21.11.GPS.1 u   13   16  3770.1370.077
> 0.054 <- Arbiter 1084C GPS Clock
> +172.17.21.12.GPS.1 u   11   16  3770.1010.085
> 0.174 <- Arbiter 1084C GPS Clock
> x172.17.21.233   .GPS.1 u   11   16  3770.0719.760
> 0.061<- LeoNTP
>
> the offset of the leontp device from the other clocks has consistently been
> in the 9.5 -10.5 range.  since I'm measuring all three sources  from the
> same (EL7) computer, I would expect that the offset of the leontp unit to
> converge to be in the close neighborhood of the offsets of the arbiters.
> It has not converged, instead maintaining the ~10ms offset.
>
> Thoughts?
>
> Thanks.
>
> Details:
>
> 172.17.21.11 is approx 400M away through two Cisco 3750G switches no
> routing.
> 172.17.21.12 is in the same rack as the leoNTP unit and plugged into the
> same 3750G switch
>
> Antenna location for the .12 arbiter and the leontp is on the same rung of
> the same tower.  Tower has clear horizon to horizon view.  cable runs are
> the same (obviously).
>
> I did run with the included puck in my south facing office window (rather
> than the GPS antenna on the tower) for a couple of days when I first got
> the unit.  The offset behaviour was the same.
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Re: [time-nuts] Measure GPSDO stability with minimum resources?

[Tim Shoppa]

The HP Smartclock app note will help you a lot:

http://leapsecond.com/hpan/an1279.pdf

There are lots of Z3801A EFC curves on the web for you to see what typical
range of unit-to-unit variation is.

Of course to actually test holdover, you do that by opening the PLL loop
(unhook GPS antenna) and letting the EFC extrapolation in your software run
for a day (or whatever), watching the phase difference. Then you have to
test that the system recovers back into phase lock smoothly after getting
hooked back up.

Tim N3QE

On Wed, Oct 5, 2016 at 1:37 PM, Bob Stewart  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.  The latter is so that I can determine that the PLL has (or
> soon will have) a good lock.  I'm developing on a dfPIC33FJ128MC802, and
> I've used about 70% of the code space,  I could probably set aside 4K bytes
> of data space for this calculation.
>
> I have a rather primitive way of doing part of this, but I was hoping
> someone would steer me to something a bit better.
>
> Bob
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Re: [time-nuts] Need Time Help

[Tim Shoppa]

I agree that the built in Microsoft tools are SNTP only and will not work
at the 15ms level.

I have had excellent success with Windows PC's of many vintages, from XP
through Windows 10, using Meinberg NTPD and the "pool.ntp.org" timeservers.

Tim N3QE

On Tue, Oct 4, 2016 at 12:41 AM, Larry Hower  wrote:

> Hello to the List:
>
> After a long and bitter struggle with XP and WIN 10, I am writing to ask
> for some help in solving some problems we have been having in our attempt
> to establish a very accurate time reference for use in EME activities.
>
> We are hoping to achieve less than 5ms deviation, although anything below
> 15ms will be adequate for now.
>
> Specifically, we want to use a universal reference that will enable amateur
> radio operators in different parts of the world to start and stop their
> transmissions within a few milliseconds of a specific time. For example, I
> transmit at 12:00:00 for 1.75 minutes and “Joe” listens. Then “Joe”
> transmits at 12:02:00 for 1.75 minutes. Repeat until QSO happens.
>
> We are using WSJT-X software. We use standard receivers plus we have tried
> a few SDRs.
>
> Sorry for the oversimplified example but I want to make sure we are all on
> the same page.
>
> As background:
>
> 1. We are using desktops and laptops in separate locations running XP or
> Win 10.
>
> 2. We have used MS clock tools, including use of Boulder time servers,
> tried both host name and IP address, without reaching the goal.
>
> 3. We have set up some Serial GPS units with PPS and some USB GPS receivers
> (no PPS) and can get to about 0.2 sec but it is not trusted or close
> enough.
>
> 4. We have set up a network time server with similar results.
>
> 5. Deviation is measured using WSJT-X
>
> -
>
> *Standard Receivers*
>
> ICOMs (910/9100 and others – non-SDR). Locked to 10MHz external osc
> reference. We have frequency accuracy of 1 to 2 Hertz at 10GHz.
>
>
> *SDRs*
>
> We believe that SDR processing can insert a delay of varying length,
> depending on the software, bandwidth, etc. Our SDR tests seem to have a
> delay of as much as 0.5 sec. And with sometimes variable results. We will
> see how SDRs can be used after we resolve the current issues.
>
>
> *Some time related hardware details*
>
> *1. Global Star 4 USB and Serial Connections*
>
> http://usglobalsat.com/p-688-bu-353-s4.aspx#images/product/large/688.jpg
>
> We have 4 of these. Two are older models with serial connections. We have
> serial ports on some computers (XP and a new high-end laptop running WIN
> 10) so we are able to activate the PPS option. Two of the GStar are newer
> models with USB connections which are not able to use the PPS option.
>
> We have tried NEMATime and NEMATime 2 software on this hardware without
> reaching our goal of <15ms. Range of deviation is from 0.0 to about 0.3
> sec. Drifts.  Deviation is measured using WSJT-X.
>
>
> *2. TimeNet NTP Device*
>
> http://www.veracityglobal.com/products/networked-video-integ
> ration-devices/timenet.aspx
>
> We have one of these TimNet units and it has been set up at 2 different
> locations on differing computers according to user instructions. We are
> using the TimNet software as DL'd recently from their web site. We get GPS
> “lock” and Time “lock” shown in the user panel but we do not have faith
> that this is carried into the system clock. Occasionally the "lock"
> indicators go blank but the time seems to be updated when the software is
> strted again (the updated is operation is show at the correct time.  We
> think the app needs some work. Deviation is measured using WSJT-X.  See
> later details.
>
>
> *Setup*
>
> The G Star units have been installed at 2 separate locations, tested using
> WSJT-X QRA 64 and WSPR-2 signals on 10.137MHz.
>
> Similar tests with a TimeNet unit at one end and G Stars at the other end.
>
> G Star units were installed on the XP laptops with the PPS option enabled
> and running WSJT-X. These XP units seem to have their time “in sync”. See
> following.
>
>
> *WSJT-X*
>
> We are not sure what, if any, internal delays there are attributable to
> this software. We have been using the same version/build at both ends for
> the tests. The software displays in 0.1 sec increments but will show 0.0sec
> when things appear to be working well. We do not know the actual level of
> precision of the WSJT-X software time measurements. I undersand that WSJT-X
> “reads” the system clock at the start of a period (TX or RX) and displays
> what it finds as the time deviation from the local system clock.
>
>
> *WIN XP*
>
> There are 2 laptops running XP. They seem to match each other re time using
> WSJT-X, both are “out” usually by less than 0.1ms or 0.2ms. We are fairly
> sure that they are working properly but they need to be more accurate
> (<15ms).
>
>
> *WIN 10*
>
> Installed on a number of desktop and laptop computers. Many efforts were
> made to make these system clocks reference the GPS devices.
>
> We became aware 

Re: [time-nuts] Jim Miller simple GPSDO

[Tim Shoppa]

There are special "wide-pull-range" VCXO's where a 10MHz unit will indeed
have sensitivity of 600Hz/V or more. e.g.
http://www5.epsondevice.com/en/products/vcxo_standard/vg4231ca.html

I don't know exactly what Epson does inside that particular unit, but a
trick to get wide pull range with discrete circuits is to put two or more
crystals in parallel.

Tim N3QE

On Wed, Sep 14, 2016 at 4:40 AM, Lars Walenius 
wrote:

> The VCXO sensitivity given is strange as it indicates a far to wide span
> so I guessed 30ppm and if it is higher it still needs the damping from
> R2-C2.
> For the OCXO I used the figures given. With 2Hz per volt and 8 Volt span
> you have 16Hz of span. 16Hz divided with 10MHz is 1.6ppm (parts per
> million) can also be said as 1.6us/s.
>
> Lars
>
> >From: Bryan _
> Sent: den 14 september 2016 03:59
>
> >Lars:
> Thank you very much, your explanation was very helpful. I unfortunately
> don't have a background in electronics other than at a hobbyist level, and
> really should just lurk in the back as many of the topics discussed are way
> above me, but I am learning . So forgive this obvious and perhaps dumb
> question but how are you calculating the oscillator spans, you reference
> the VCXO at around 30ppm. I suspect this is because the VCXO has a
> sensitivity of 600-1000hz/v and the OCXO of 1.6ppm has a sensitivity of
> 2hz/v or 3.2/v at 8v. But how are you arriving at the ppm values?
> -=Bryan=-
>
> >> From: lars.walen...@hotmail.com
> > To: time-nuts@febo.com
> > Date: Tue, 13 Sep 2016 20:44:50 +
> > Subject: Re: [time-nuts] Jim Miller simple GPSDO
> >
> > As I have understood it the change of VCXO gain is the reason that R2-C2
> can be omitted. With the VCXO with a large span the damping is needed
> otherwise it will oscillate.
> >
> > The XOR phase detector has a range of 50us with 10kHz in.  The VCXO has
> maybe a span of 30ppm (us/s) and with R1-C1 time constant of about
> 16seconds the phase shift will be close to 180 degrees.
> >
> > With the OCXO with a span of 1.6ppm (us/s) the apparent time constant
> will be about 32 (50/1.6) seconds and the 16 seconds time constant of the
> R1-C1 will act more as a low pass filter at gain cross over with a phase
> shift much below 90 degrees.
> >
> > Sorry for the bad explanation but what I try to say is: If the phase
> detector range  divided with the VCXO span is larger than the R1-C1 time
> constant R2-C2 can be omitted.
> >
> > This thread on EEVblog might be interesting for those that think of
> using the Miller-style GPSDO:
> > http://www.eevblog.com/forum/projects/my-u-blox-lea-6t-
> based-gpsdo-(very-scruffy-initial-breadboard-stage)/msg938013/#msg938013
> >
> > Lars
> >
> > >From: Bryan _
> > >Sent: den 12 september 2016 10:49
> >
> > >Thank you for the reply.
> > Yes, R1/R2/C1/C2 is what I was referencing. I was not sure as the values
> in the schematic are referenced when using the C-MAC (now RAKON) VCXO.
> Further into the material the author switched to a Isotemp 134-10 OCXO and
> used a DC amplifier to compensate for the 0-8v for the EFC, but stated that
> R2 and C2 are not needed when using this OCXO. Not sure why they are
> omitted, is it because of the DC amplifier or because of different specs of
> the OCXO?
> > http://www.jrmiller.demon.co.uk/projects/ministd/dcamp.gif
> >
> > -=Bryan=-
> >
> > >> Date: Mon, 12 Sep 2016 01:25:53 -0700
> > > From: wb6...@cox.net
> > > To: time-nuts@febo.com
> > > Subject: Re: [time-nuts] Jim Miller simple GPSDO
> > >
> > > Hi Bryan,
> > >
> > > No !  Assuming you mean R1/R2/C1/C2 of the Miller schematic, those
> > > values are already set for the comparison frequency (10KHz) of the PLL
> > > phase comparator (U2).
> > >
> > > BillWB6BNQ
> > >
> > >
> > > Bryan _ wrote:
> > >
> > > >Hello:
> > > >I have been following the Jim Miller simple GSDO build project at
> http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm  I have a
> few OCXO's kicking around, but wondering what would the appropriate
> components be for for  R1,R2, C1, C2 to provide the PLL filter. I assume
> the PLL filter needs to be designed to accommodate a specific oscillator
> specifications, or maybe it doesn't really matter and can use the default
> values in the schematic?.
> > > >Was also considering using a picdiv instead of the 2- 74HC390, not
> sure if that would be an advantage or disadvantage in terms of operating
> performance?
> > > >Cheers
>
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Re: [time-nuts] A new take on the all-hardware GPSDO concept

[Tim Shoppa]

You know Nick, the loop time constant typically used with the HMC1031 loop
filter is typically 5 milliseconds. I'm sure some bigger R's and C's can
used for a longer time constant, and I'm sure that'll help clean up the
awful 10MHz output of the Venus838LPx-T. But it is hardly what I'd call a
"GPSDO".

Tim N3QE

On Mon, Sep 12, 2016 at 2:41 PM, Nick Sayer via time-nuts <
time-nuts@febo.com> wrote:

> I was talking with someone at AD about a question I had about one of their
> TinyDACs when they mentioned their HMC1031 chip. It looks like the ideal
> building block for a clean-up oscillator.
>
> It struck me just a touch later that the Venus838LPx-T has by default a 10
> MHz output that’s phase locked to GPS time. It’s not good quality, but I
> wonder if it’s good enough to be the reference for this particular chip.
> They do talk about the ability to be driven by a “noisy” or "jittery”
> reference.
>
> I think I’m going to take a crack at an OH300 GPSDO based on this design
> concept. Actually, first I’m going to actually try to quantify the jitter
> on the 10 MHz output from the Venus. From the HMC1031 datasheet it appears
> that if it’s not confined to a ±3 ns corridor that the lock indicator may
> not work (or work well). That would be a bummer.
>
> I can foresee a GPSDO with the miniDIN 4 jack presenting the PPS and
> serial I/O from the GPS module and two LEDs on the front - the “FIX” LED
> from the GPS module and the lock LED from the PLL along with two BNC jacks.
> It would have some downsides. For one, I believe in the absence of GPS
> reception, it wouldn’t be able to properly hold-over at all. But it’ll be
> interesting to see if it can work as well as the micro-controller driven
> variant does.
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Re: [time-nuts] What's the best Windows 10 ntp client?

[Tim Shoppa]

For a Windows machine that is always on, I would strongly recommend
Meinberg NTPD as "easy to install and the real deal". And free. It works
just fine under Windows 10.

Dimension 4, I am not impressed by, but if the only thing it has to do is
set the clock at boot time, then it might be OK. But I think Windows 10
time service is good enough to do that out-of-the box from Microsoft.

Tim N3QE

On Fri, Sep 2, 2016 at 2:29 AM, Dr. David Kirkby  wrote:

> At my amateur radio club we have Internet access via a WiFi dongle with a
> Pay As You Go card. A Windows 10 PC is only powered up while we are there,
> so on around 2-4 hours per week.
>
> Does anyone have any thoughts on what might be the most suitable software
> to run on our Windows 10 PC to set the time correct?
>
> Someone installed "Dimension 4"
>
> http://www.thinkman.com/dimension4/
>
> As far as I can see, this takes the time from one single NTP server, which
> I believe is not a good idea.  However,  given we only run the PC on 2-4
> hours per week,  maybe no ntp client will work well,  but I would have
> thought using multiple servers being better than one.
>
> I am wondering if anyone has any better suggestions for software. .
>
> Dave.
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Re: [time-nuts] Safely getting the electrical length of a connected antenna feedline

[Tim Shoppa]

You left out the obvious time-nut solution: Calibrate and characterize an
ensemble of HP5071A's to correct absolute time at NIST. Transport the
ensemble (correcting, if necessary, for general relativisitic effects) to
your house. Set the cable delay in your GPS receiver to zero. The delta
between your receiver PPS and the HP5071A Ensemble is the time delay in
your cable and GPS Antenna - AFTER you account for the time delta between
USNO and NIST time (available at
http://www.nist.gov/pml/div688/grp50/nistusno.cfm )

Tim N3QE

On Mon, Aug 8, 2016 at 2:18 PM, Bob Stewart  wrote:

> Earlier this year, with some help, I pulled the dish off of an old DishTV
> antenna on the roof and put a 5V bullet antenna on the mast.  I also pulled
> a new cable through by attaching it to the old one.  The problem is that I
> was not able to measure the new cable.  So, the question is, without going
> back on the roof in this heat, how can I measure the electrical length of
> the line I pulled?
>
> I was thinking of using my 8640B signal generator and sending some RF back
> up the line to get a quarter wavelength at the null.  But that assumes a
> lot, including that the other end is open at 3MHz, or whatever the
> frequency works out to be, as well as that the high voltage on the antenna
> end won't be high enough to blow the LNA.
>
> So, how much RF I can safely send up the line?  I've got an 8558B spectrum
> analyzer, but it's not on the bench, and it would be easier to use my
> scope, which sadly is a 70s vintage Tek 455.  Do I put this all together
> with a lead from the generator to a tee at the measuring device and tune
> for a null?  My experience at getting precise measurements on anything
> longer than a few inches is effectively none, but I'd guess that I want
> less than 0.5V at the LNA during this test.  Oh, and I do have an 8444A
> tracking generator that can output -10 dbm as well as a 10 db attenuator
> within easy access.  That could get a quick spot on the null point.
>
> Most importantly, of course is the question of whether this will even
> work.
>
> Bob - AE6RV --
> ---
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Tim Shoppa]

My first ever GPS receiver was a surplus SV6. Wow, that's a primitive
receiver. The PPS would shift by 6 milliseconds (not microseconds, but
milliseconds) every time I didn't have enough satellites in view.

Tim N3QE

On Tue, Aug 9, 2016 at 4:34 AM, Hal Murray  wrote:

>
> ziggy9+time-n...@pumpkinbrook.com said:
> > It IS possible to hack a ’standard’ SV6 receiver such that it will work
> in
> > the XL-DC...
>
> Did your XL-DC have an actual SV6 in it?  I didn't see one in the picture
> Rick sent out a few days ago.  There was a Trible sticker on a chip so I
> suppose the logic from  a SV6 could have been laid out as part of another
> board.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
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Re: [time-nuts] The home time-lab

[Tim Shoppa]

Everyone else is talking as if these blips can be protected from, by having
a UPS supplying your precious lab equipment.

I strongly disagree.

What happens, is you have transformers, fluorescent ballasts, and motors
(e.g. HVAC blowers) in the vicinity of your lab equipment. Probably on a
completely different AC branch circuit, and not even necessarily in the
same room but maybe in an adjacent room or above or below your lab. With an
inductive load, every time there's a sudden power cut, a large back-EMF
develops and then the power suddenly comes back on and then there's a
sudden large current as the magnetic fields are built back up. It's these
transient magnetic fields from your non-lab equipment, that is what's
disrupting your measurement.

If you now add a UPS in the vicinity of your lab equipment, and it of
course has a transformer in it, it will likely add to the disruption in a
power glitch.

Of course things are a little different if you banish all AC power from a
few hundred feet of your lab and only run sustaining charging current for
the DC batteries developed in a far-away DC supply :-).

Tim N3QE

On Thu, Jul 7, 2016 at 8:44 PM, Bob Stewart  wrote:

> I hope this isn't too far off topic, as this is having a big impact on my
> testing.
>
> I decided to run an A/B test on one of my GPSDOs: comparing the phase of
> the two 10MHz output channels.  In the middle of the night, there was a
> long series of 35ns pops in the phase data.  Strangely enough, there was
> nothing in the data collected directly from the unit involved.  The
> preceding two days we had had a number of switching transients where the
> lights blinked but nothing shut down.  So, putting one and one together, I
> suspect that a fair percentage of the strange results I've been getting has
> been power-grid related.
> So, what to do?  I've been looking at UPS devices, and I don't even
> understand enough to waste my money on a bad one.  The two big questions
> seem to be "on-line" and "sine wave".  Make that three: can I trust the
> mfgs claims?  Is there something affordable that could run a pair of 5370s
> and maybe another 50W worth of DUTs for up to an hour or two and not be
> prey to power-line transients?  Or would it be more cost effective to
> somehow monitor the power line for spikes or phase jumps and blow off tests
> or cut out the offending data?  From time to time we get a thread on
> power-line nuts.  Should I have been paying more attention?
>
> Bob - AE6RV
>
>  
> ---
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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Re: [time-nuts] The home time-lab

[Tim Shoppa]

1/35ns is about 30MHz. Is there anything in your clock chains that is
ticking at 30MHz, such that a false count or slipped count induced by
inductive disruption, would cause a 35ns phase jump?

Related thread:
https://www.febo.com/pipermail/time-nuts/2016-May/098028.html

Tim N3QE

On Thu, Jul 7, 2016 at 8:44 PM, Bob Stewart  wrote:

> I hope this isn't too far off topic, as this is having a big impact on my
> testing.
>
> I decided to run an A/B test on one of my GPSDOs: comparing the phase of
> the two 10MHz output channels.  In the middle of the night, there was a
> long series of 35ns pops in the phase data.  Strangely enough, there was
> nothing in the data collected directly from the unit involved.  The
> preceding two days we had had a number of switching transients where the
> lights blinked but nothing shut down.  So, putting one and one together, I
> suspect that a fair percentage of the strange results I've been getting has
> been power-grid related.
> So, what to do?  I've been looking at UPS devices, and I don't even
> understand enough to waste my money on a bad one.  The two big questions
> seem to be "on-line" and "sine wave".  Make that three: can I trust the
> mfgs claims?  Is there something affordable that could run a pair of 5370s
> and maybe another 50W worth of DUTs for up to an hour or two and not be
> prey to power-line transients?  Or would it be more cost effective to
> somehow monitor the power line for spikes or phase jumps and blow off tests
> or cut out the offending data?  From time to time we get a thread on
> power-line nuts.  Should I have been paying more attention?
>
> Bob - AE6RV
>
>  
> ---
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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Re: [time-nuts] Cable length calibration

[Tim Shoppa]

We are all time nuts, so there's an obvious answer: What you do, is raise
the GPS up to a height the same as the cable length. You then drop it,
measure the time until it hits the ground, and use d = 0.5 a * t * t to
calculate d. Then you correct for the velocity factor.

Tim N3QE

On Wed, Jun 29, 2016 at 3:28 PM, Hal Murray  wrote:

>
> bro...@pacific.net said:
> > At one point they were looking into making a GPS time receiver where the
> > cable length calibration would be built-in.
>
> How would you do that?
>
> The obvious way is to compare the time you get with a known-good time, but
> if
> you had that, why would you want this new GPS with an unknown cable length.
>
> You might be able to do it by measuring the DC drop.  Getting enough
> accuracy
> seems tough.
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Tim Shoppa]

Bob -

  Crystal resistance of 100K probably applies to the large low frequency
crystals. Modern HF fundamental crystals tend to be around 50 ohms at their
fundamental and I think higher for overtone crystals. Older crystals in the
HF range in the FT-247 holders seem to usually be several hundred ohms.

  I've certainly swept crystals before to look for spurs, but I usually use
small sweep ranges like a few hundred Hz around where I know the spur to be
anyway. This is kinda like the drunk light only looking under the
streetlights for his keys because he knows he'll never find them if they're
anywhere else. Not to sound too pessimistic but when applying this to
crystals from the 50's it seemed like it was a lot easier to find the spurs
than the fundamental!

Tim N3QE

On Sat, Jun 4, 2016 at 8:29 AM, Bob Camp  wrote:

> Hi
>
> Simple approach is to assume that you have a crystal resistance in the
> range of 100K ohms. If you guess to
> high, the oscillator will just work to well :)
>
> Multiple JFETS in cascade for the higher frequency stuff should work. For
> anything below 20 KHz, an op-amp
> is likely your best bet.
>
> A spectrum analyzer with a tracking generator will give you some idea of
> their impedance and *if* they still have
> any activity at all.
>
> Bob
>
> > On Jun 4, 2016, at 4:46 AM, Mike Cook  wrote:
> >
> > Hi,
> >
> > I have a number of crystals either in glass, bakelite, ceramic or metal
> housings that I would like to get resonating . They are of three basic
> types.
> > Square, or rectangular flat
> > Round flat
> > Bar  square section
> > Sizes range from 2-10cm or more in the longest face.
> >
> > Some have frequency markings. ranging from IKHz 5MHz.
> > Others have none.
> > Some are of  Military origin, probably radios and as they have markings
> I can probably find a schematic from the radios to see how to proceed.
> There may be dedicated testers still around. I am not so interested in this
> bunch at the moment.
> > Others have no known origin so I have no idea what oscillator circuits
> were used with them.
> > In terms of vintage, I would guess pre 1940  to late 50s
> >
> > I have built a little Pierce circuit an tried a few. Some of the later
> 1-5MHz crystals will oscillate but there are a lot of parasitic signals as
> well as the supposed fundamental. I cannot make any of the low frequency /
> big crystals to react.
> >
> > So my question:
> > If you had a crystal with unknown frequency and drive requirements that
> you wanted to investigate. How would you go about it?
> >
> > If I can get them going I will share the Adevs. I don’t have a spectrum
> analyser so I can’t do phase noise.
> >
> > Regards
> >
> > "The power of accurate observation is commonly called cynicism by those
> who have not got it. »
> > George Bernard Shaw
> >
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Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

[Tim Shoppa]

With random old crystals in holders, it often helps to disassemble the
holder and clean crystal and holder plates with alcohol (my favorite back
in my youth was carbon tetracholoride but not so easy to find these days.)
I'm guessing most of your round blanks were for FT-243 type holders.

The Pierce logic-gate-biased-active oscillator is pretty reliable to start
and will oscillate somewhere with most crystals from kHz to MHz.

As you found out, it will often come up on one of many overtones.

To reduce chance of coming at an overtone, a series resistor from logic
gate output to the crystal is often enough. If not, a RC low-pass will cut
down even further (although of course adding phase shift.)

Many surplus crystals from the 50's will be marked with their series
resonant frequency. The military surplus tank crystals are marked with
channel number. By the 60's and 70's, crystals for VHF radios were often
marked with the channel frequency (that's after multiplication and mixing
with IF if a receive crystal.)

Tim N3QE

On Sat, Jun 4, 2016 at 4:46 AM, Mike Cook  wrote:

> Hi,
>
> I have a number of crystals either in glass, bakelite, ceramic or metal
> housings that I would like to get resonating . They are of three basic
> types.
>  Square, or rectangular flat
>  Round flat
>  Bar  square section
> Sizes range from 2-10cm or more in the longest face.
>
> Some have frequency markings. ranging from IKHz 5MHz.
> Others have none.
> Some are of  Military origin, probably radios and as they have markings I
> can probably find a schematic from the radios to see how to proceed.  There
> may be dedicated testers still around. I am not so interested in this bunch
> at the moment.
> Others have no known origin so I have no idea what oscillator circuits
> were used with them.
> In terms of vintage, I would guess pre 1940  to late 50s
>
> I have built a little Pierce circuit an tried a few. Some of the later
> 1-5MHz crystals will oscillate but there are a lot of parasitic signals as
> well as the supposed fundamental. I cannot make any of the low frequency /
> big crystals to react.
>
> So my question:
> If you had a crystal with unknown frequency and drive requirements that
> you wanted to investigate. How would you go about it?
>
> If I can get them going I will share the Adevs. I don’t have a spectrum
> analyser so I can’t do phase noise.
>
> Regards
>
> "The power of accurate observation is commonly called cynicism by those
> who have not got it. »
> George Bernard Shaw
>
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Re: [time-nuts] How can I generate a very clean 1 W signal @ 116 MHz ?

[Tim Shoppa]

OK, it sure sounds like you want to use a commercial signal generator or
something. But a different take:

14.5MHz is a standard stocked crystal at Mouser, Digikey, etc. Three stages
of doublers with simple fundamental-reject filters at each stage get you to
116 MHz.

If you want to make it time-nutty, there's the NIST JFET "push-push"
frequency doubler we've talked about here in the past. I think you'll use
substantially smaller number of turns on the 116MHz stage than on the
14.5MHz end of the transformers.
http://www.ko4bb.com/~bruce/FrequencyMultipliers.html

Tim N3QE

On Mon, May 30, 2016 at 7:06 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> I was thinking about designing a 2 m (144-146 MHz) ->HF (28-30 MHz)
> transverter, using a 116 MHz local oscillator feeding a level 30 mixer.
>
> 116 + 28 = 144
> 116 + 30 = 146
>
> I'm wondering what's the best way to generate 116 MHz with very low phase
> noise. Phase noise at < 20 kHz offset is particularly important, but 200
> kHz would be fairly important. Outside that, it does not matter too much.
>
> The ability to lock to 10 MHz would be "nice", but certainly not essential,
> as absolute frequency stability would not be of prime importance. Getting
> the phase noise as low as possible would be more important. I expect better
> performance can be achieved if one forgets about locking the signal source
> to something else, but I may be wrong.
>
> An HP 8663A sig gen has <-147 dBc/Hz at 10 kHz offset, but I'd hope its
> possible to produce something better than is possible in a commercial sig
> gen that covers up to 2.5 GHz.
>
> Dave
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Re: [time-nuts] Maser 0.7 nsec jumps solved

[Tim Shoppa]

Interesting math: Hydrogen maser frequency standards use the 1420 MHz line.

Period of 1420MHz is 0.7 ns.

It's not so clear to me that the maser itself is being disrupted, it seems
more likely the external noise is inducing an extra count or causing a
count to be slipped.

A different Australian observatory 1400 MHz RFI problem:
http://arxiv.org/abs/1504.02165 "Subsequent tests revealed that a peryton
can be generated at 1.4 GHz when a microwave oven door is opened
prematurely and the telescope is at an appropriate relative angle. Radio
emission escaping from microwave ovens during the magnetron shut-down phase
neatly explain all of the observed properties of the peryton signals."

Tim N3QE

On Sun, May 22, 2016 at 7:43 AM, 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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Re: [time-nuts] patents and hobbyist projects (was: Temperature controlled TCVCXO)

[Tim Shoppa]

In addition to what others write about nobody will come after you for
hobbyist/testing purposes...

It is surprisingly easy for a patent non-professional to be confused, about
what a patent actually covers (claims) vs does not cover (claim).

There is a section called "description" that is useful and interesting for
techie guys. Especially when the patent was the result of a actual real
device, anyone skilled in the field will be able to read the "description"
section of a patent and figure out the device and learn something from the
patent. The "citations" and "referred to by" are usually interesting
reading too.

Beyond that, there is a section called "claims" that actually sets out the
legal language about what the inventors, and their patent lawyers, and the
patent examiner, eventually decided (probably over a period of months to
years) could be patented. Reading the claim section is surprisingly tricky.
Lots of interesting things (to you and me) in the description are probably
not actually claimed because they were claimed by previous patents (See the
patent citations at the bottom). When I'm in a room with the patent lawyers
and they are telling me how to read it, I can manage to follow them and
even learn a little bit of the patent phrase-ology in a way that makes
sense to me. These lessons in patent phrase-ology stick with me for only a
matter of days after we leave the room. The language of the claims is very
highly specialized, and even further the patent lawyers have "optimized"
the claims, so that base claims are elaborated on in a very complicated and
ornate way in later claims such that a challenge to any one claim of the
patent will have minimized the effect on negating the whole patent.

Tim N3QE

On Sat, May 14, 2016 at 5:56 AM, Attila Kinali  wrote:

> On Fri, 13 May 2016 19:32:58 -0500
> David  wrote:
>
> > Thanks for those.  I went over them pretty carefully and what I am
> > proposing is not covered by either although that would not protect me
> > from a debilitating patent lawsuit.
>
> I wouldn't worry about patent lawsuits at all unless you intend to
> start a multi-million business.
>
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