>From 2002, 5 million samples, 5065A vs. 5071A, drift rate 2e-12 per month:
http://www.leapsecond.com/pages/doug-rb/
/tvb
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To unsubscribe, go to
Steve,
> I need the rising edges of both the 10 MHz and 100 MHz squarewave outputs
> to be aligned with the GPS 1 pps (UTC) to within 1 ns.
Two comments.
1) If you divide 100 MHz -> 10 MHz -> 1 Hz then (with careful design,
calibrated layout / wiring) you can have all three rising edges within
Thanks Leo.
For you low level time nerds, yes, even DoD can't get GPS time / UTC / UT1 /
leap seconds right the first time. Synchronizing 3 time scales across a leap
second discontinuity is really, really hard. More info about ICD rev-J here:
> I wonder if anybody will market a GPS-to-WWVB translator?
> Dana
You can find lots of these projects on the web: in the time-nuts archives,
eevblog, hackaday, or sometimes completed multi-band kits (WWVB / DCF77 / JJY)
on eBay.
Search for a couple of words like signal wwvb simulator
Corby,
Nice detective work. Keep us posted. I had a case some years ago where my IF
level was sputtering around. It turned out to be the dissociator. It was a
pretty easy fix after a fax / email or two from Russia.
If you suspect the L.O. you can always free-run it for a week and see if
> Is there a time-nuts FAQ?
Hi Ron,
We've considered that several times. There are problems.
Also it's hard to beat the already superb NIST Time & Frequency FAQ / A-Z
glossary. There's an index, or just start with A and read through several dozen
webs pages until you get to Z:
Bernd,
Typically all you want is the leading edge. So a 10 or 20 us wide pulse is
enough for most purposes. The duty cycle is essentially zero in this case.
A noted exception is when the pulse is detected using vintage RS232 modem
signal inputs, for example, when NTP uses DCD to catch a 1PPS.
> Arecibo did a kind of cute trick with their distributed 1PPS. The one
> second pulses were of one length
> (100 ns as I recall), but the 10 sec boundaries had the pulses be about
> twice that length. One could carry
> this scheme to considerable lengths as desired.
Dana,
One version of this
What a weekend. Just a reminder -- our "low volume, high SNR" time-nuts list
works best when postings are technical and well-informed. Quite a few of the
many NIST-related postings since Friday fell below that threshold.
Undoubtedly an accurate story will come out soon. If you know something
> Should the multiplier value be +1.0e-09 or +1.0e-10?
I worked with Chris off-list on this one. It turns out he was measuring his new
PRS10 and trying to match his ADEV plots against the published plots from SRS.
Hence the request about 1e-9 (which is ppb and should be
This is reminder that time-nuts is a technical mailing list. If you know
something about WWVB for sure, please post. If you're just guessing,
speculating, spreading rumors, or just ranting please don't make 1800 other
people read your posts.
I don't know where some of you get the idea that
> Seaside as in near Sand City, Monterey & Fort Ord? That's quite a drive
> down to Palomar, no matter which route you take.
Hi Jim,
Sorry, s/Sea/Ocean/
Oceanside, CA; between Los Angeles and San Diego. Driving from the beach to the
summit of Mt Palomar was just over an hour. A gorgeous
Some of you met, worked for, or at least know of Al Bagley. He was one of the
early guys at hp and very involved with time & frequency.
(1) Here is recent news via https://www.seti.org/remembering-al-bagley
"
Al Bagley, one of the transformational engineers in Hewlett-Packard's early
days and a
> I suspect there’s a longer list of “slow” environmental effects that are also
> taken
> care of with the compensation setup. One would guess that crossing a active
> fault line would be “interesting”.
Yes, here's a back of the envelope calculation for you:
- the Pacific Northwest moves on
> i have been lucky to found a working Oscilloquartz 3210 Cesium ( warehouse of
> a telco operator ) in a good shape.
Nice find. The OSA 32xx manual that I scanned is at:
http://leapsecond.com/museum/osa3200/
That's 33 pages of "Operating and Instruction Manual". If your unit is working
> "I think", that if for example, it takes 1 second to drift one cycle,
> that works out at 0.1 ppm. If it takes 2 seconds, it's 0.05 ppm, if it
> takes 5 seconds, it's 0.02 ppm etc. Is that correct?
Yes. At 10 MHz one full cycle is 100 ns. So if the cycles are drifting by 100
ns per second
] lower than the performance of an actual frequency standard.
Once you fire up your GPSDO and use that as a reference, your PRS10 ADEV/MDEV
numbers will look more appropriate.
/tvb
- Original Message -
From: Chris Burford
To: 'Tom Van Baak' ; 'Discussion of precise time and frequency
Ferran,
> The synchronization goal is in the order of ps level.
I'm glad you mentioned your requirements. Note that time synchronization at a
"ps level" is 3 to 4 orders of magnitude beyond what the typical commercial or
eBay or DIY GPSDO will do.
But as you imply, you're only using GPS to
David,
Just to see if your setup is working:
1) Set the pulse generator to as fast a risetime as possible; ns or less. Use a
low pulse rate (100 Hz is fine).
2) Use a BNC tee at the generator, into two equal 2 meter cables, each one into
a 5370B input.
3) Set manual trigger, 50R, 1.0 V, DC
4)
> I have in mind a project which consists in synchronizing two or more stable
> clocks (OCXO) disciplined by GPS.
>
> However, would be great to have the option to disable the GPS on both sides
> at a given time and to synchronize them in a Master-Slave or directly by means
> of a protocol they
Hi Ferran,
Here's another idea for your multi-OCXO synchronization project.
Normally when we think about synchronized oscillators we imagine two of them in
side-by-side or perhaps separated by a few meters of cable. Through some PLL
magic they remain in perfect phase (and frequency), either
> In case the screenshot does not make it though;
> W PM starts at 1.69e-9
For this you should expect 1.73 which is sqrt(3). For example:
C:\tvb> rand1 100 | adev4 /a 1
rand1 100(count) 1(sdev) 0(mean) 1540577979(seed)
** tau from 1 to 1 step 1
1 a 1.732671e+000 98
> W FM
Ole,
> I'm simulating some noise to try to improve my somewhat sketchy
> understanding of what goes on with the various noise types as shown on an
> ADEV plot. Nothing fancy, ~3600 points of gaussian random numbers between 0
> and 1 in excel, imported into Timelab as phase data, scaled to ns.
I
> http://lists.febo.com/pipermail/time-nuts_lists.febo.com/2018-October/094520.html
Pardon the interruption. If any of our 1800 members uses a Samsung / Galaxy Tab
to compose email and can help Bert with his formatting issues, please contact
Bert (ewkeh...@aol.com) or me (t...@leapsecond.com)
> With the idea that, when the adjustment loop is deactivated, an external
> signal
> can be supplied to the Thunderbolt, and the Time Interval circuit could show
> the
> difference in between this signal and the feedback of the VCO.
I understand what you're trying to do. Your idea would work
> I have in mind a project which consists in synchronizing two
> or more stable clocks (OCXO) disciplined by GPS.
If the OCXO are disciplined by GPS then you have a GPSDO. There is no need,
then, to synchronize the OCXO directly; they are all synchronized indirectly
through GPS. Or perhaps I
Daniel,
There's simple C code at http://leapsecond.com/tools/adev_lib.c that does ADEV
/ MDEV / TDEV / HDEV.
A sample ADEV program using that code is: http://leapsecond.com/tools/adev1.htm
There are Python versions on the web if you're into Python and its ecosystem.
If you want a QBASIC version
Bob, et al.
In general there's no problem using the list to sell or trade or give-away T
gear. Especially if it's good stuff like what you have! The only thing we ask
is that this benefit of using time-nuts as a marketplace be used sparingly.
Some suggestions...
It's best to collect a pile of
http://leapsecond.com/tools/alarm.c (alarm.exe)
[2] http://leapsecond.com/tools/url.c (url.exe)
[3] http://leapsecond.com/tools/daytime.c (daytime.exe)
- Original Message -
From: Peter Vince
To: Tom Van Baak ; time-nuts@lists.febo.com
Sent: Monday, October 01, 2018 2:14 AM
Subject: Time
> Dave B. (G0WBX)
>
> PS: I do like the idea of setting up a camera to take a photo of the
> 'scope every hour or so! Not practical for many I guess, but it
> illustrates the point well. But the aliasing opportunity I think would
> be perhaps too great, in essence being a sampled data system by
What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out of 10
MHz? Low phase noise isn't a big requirement and jitter doesn't need to be
sub-nanosecond. The main requirement is perfect cycle count accuracy. This is
for driving a 16 MHz microcontroller from a 10 MHz Rb/Cs/GPSDO. 10
Hi Graham,
That's very nice work. And you have uncovered several unusual effects in the
ES100. Bugs? Features? If we time nuts keep up the good work to evaluate this
chip, we are likely at some point to get an informative response from the guys
who designed it. They read time-nuts.
So now
Hi Gilles,
Correct, the log-log slope will be -1.
But I'm not sure about your ADEV and SigmaTIC claim.
Assume the 53132A has 150 ps RMS resolution. The standard deviation is also 150
ps. The Allan deviation at tau=1 would be 1.73 * 150 ps/s or 2.60e-10.
Look at calc_adev() in
> Use the Rb as your reference and log the time offset of its PPS.
> Manually steer vs a 10 hour GPS PPS data set once a week.
> You probably will stretch it out to a couple weeks after things settle in.
I'm with Bob here. Once a week, once a month, once a year, even once a
lifetime: the choice
Hugh,
What year is your photo from? Here's a similar, but older photo of hp's house
standard:
http://leapsecond.com/history/Benchmark.htm
This was from roughly 1966 (note the dual hp 5060A). The HPJ issue containing
that article is here:
> What are the units on the lower right with pairs of analog meters?
Hal,
Those are all 24 VDC backup power supplies. Model hp 5085A. The round meters
are for volts and amps.
Take a look through http://hpmemoryproject.org/an/pdf/an_52.pdf which is an
nice old (1965) copy the classic hp AN52
> I see the different forms of deviation measurements and they are all
> one-to-one comparisons.
Not all. But, yes, often. UTC itself is a wonderful example of making mutual
measurements of several hundred atomic clocks and establishing a superior
"paper" clock out of them collectively.
But
Tim -- Thanks much for that initial ES100 report. Within a day,
universal-solder.ca sold out their initial inventory of these dev boards so I'm
expecting a flood of technical reports here on the list.
Graham -- Thanks for your comments on I2C. That will surely help others who get
frustrated
I updated the http://leapsecond.com/pages/ultratomic/ teardown page with a
performance plot made from data last year.
The plot is at http://leapsecond.com/pages/ultratomic/ultratomic-10d-2.png
The La Crosse 1235UA UltrAtomic radio controlled wall clock, which came out a
few years ago, uses the
At long last, a complete WWVB 60 kHz BPSK dev board is available:
https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
Note it includes the antenna(s). Also has links to documentation.
It would be very nice if a bunch of time nuts around the
> Tom is currently working his magic on the raw data captures with Timelab.
> The results so far are looking very good and much more informative.
Mark's experiment was nicely done. Here's the first set of TimeLab plots:
http://leapsecond.com/u/sims/gpsdo17/
If that's too much, just look at the
> Surely, this is nothing new?
Once or twice a year some national lab, often NIST, makes an announcement of a
new level of precision for their atomic clocks. It's pretty cool, actually.
It's good PR. The rate of progress is amazing.
> I thought standard pendulum clocks were quite good at
> That was the first time that I had seen an xy plot of WWV versus a
> stable crystal oscillator. It is even worse than I thought. I had to
> look up FRK to see that it is a rubidium standard. I talked to Jim
> Maxton the chief engineer of WWVB many times around 1995.
An xy cycle of WWV is
Jim Lux wrote:
> I'm not sure I understand why the slowing due to spin happens to exactly
> match the speedup from altitude.
Right. It's not obvious to me either. I've been looking some time for the right
book, article, or web page to hand out when people ask that question. The same
goes for a
Donald E. Pauly, WB0KVV wrote:
> Ft Collins is at 5,003 ft and clocks there run fast by 1.663·10^-13.
> (g/c^2)/meter) compared to sea level. How did you correct for
> altitude on yours? I presume that frequency is defined at sea level
> but I don't know that.
Yes. Standard time & frequency is
The Z12T is a bit old by now, although some of us own or have used them. Z12
documentation is available on multiple archived Ashtech web sites. Lots of
conference / technical papers describing time transfer with Z12T receivers
exist. AFAIK a number of national timing labs still use them.
What
I checked the TBoltmon files at http://leapsecond.com/pages/tbolt/ and they're
fine.
Grab a new copy if you suspect something wrong on your end.
The usual reason that you get a com port error is that the port doesn't exist,
or that it's beyond com16.
Does this old computer have native com ports
> OK, now I've got it. I wasn't seeing the humps as being many slight
> variations
> around the 50ps points. Just had my mental scaling all wrong.
> In other words, the TICC's resolution is "blurred" around the nominal value
> rather
> than being aligned to a precise increment.
John,
Yes,
> If you are working on the firmware, consider adding a time-nuts mode that
> also
> includes the post-calibration data.
Hal,
When you power up the TICC, go into D (debug) mode.
Then instead of just outputting timestamps, it will output:
# time1 time2 clock1 cal1 cal2 PICstop tof timestamp
its resolution. For example, the 5334A
> with 2ns resolution will always show bins no less than 2ns apart.
>
> What am I missing?
>
> John
>
>
> On 1/8/19 3:34 PM, Tom Van Baak wrote:
>> John,
>>
>> Your hunch is correct. For most modern TIC devices, me
> In his comment below, Mark has used the word "decimate".
I contacted Mark about this as soon as he posted yesterday. It turns out he did
not mean decimate. It's just the word he accidentally chose. He was offering an
opinion on precision or resolution; not decimation.
Decimation involves a
This thread is for the topic of hp and atomic clocks.
Time-nuts is not about wristwatches or radium dials, or Rolex or tritium or
Waltham, ...
Please take your off-topic tangents elsewhere (there are many wristwatch forums
on the internet).
/tvb
Moderator, http://leapsecond.com/time-nuts.htm
> Hi All sorry for a new be question but
> what is a TICC
> regards Paul B UK
Hi Paul,
That is an acronym we often use here on time-nuts; one that a simple google
search doesn't answer.
Ok, there's "TIC" and there's "TICC".
1)
A TIC (Time Interval Counter) is a common 2-input electronic
> I once showed the CEO our brand new $100K cisco AGS+ router. It
> was kitted out to the hilt with ethernet interfaces, but the front
> side he saw had only the orange bridge siloutte and a single green
> power LED. He looked at it and then said "For that kind of money,
> couldn't they at least
> I don't think case A makes sense. You are throwing away information. You
> will get aliasing.
Hal,
Ah, but we do this all the time. Your GPSDO or your cesium standard outputs 10
MHz. There are many cases where throwing 9,999,999 of every 10,000,000 is
useful. The result is ... 1PPS.
Yes,
> This email chain has unleashed a flood of memories from 30 years ago.
> Hopefully a few of you find this walk down memory lane interesting.
> I have a few more stories in the que if any of you are still interested.
>
> Hugh Rice
Somewhere in my library I have an internal hp document describing
l issues,
TDEV should be flat from tau 1 to forever.
f) Subtle, unwanted variations are much easier to observe in a flat line (TDEV)
than a -1 line (ADEV).
/tvb
- Original Message -
From: "Club-Internet Clemgill"
To: "Tom Van Baak" ; "Discussion of precise time a
> Does anyone have a pointer to information about the absolute time
> accuracy (not stability) that was available via PZT or other techniques
> prior to the Cesium definition? I'm doing a presentation and want to
> show the evolution of accuracy. My Google-fu has failed me in finding
>
Some of you know that I'm a pack-rat for vintage instruments, books,
documentation, and publications about atomic clocks. Especially anything by
Hewlett-Packard. I've enjoyed all the time-nuts posting by Rick Karlquist and
Hugh Rice, et al.
The usual online hp sources [1] host the massive
> I have been pondering something somewhat related to all of this.
JohnA started and then concluded this thread about pre-Cesium time accuracy.
Musings about quantized time gets pretty far off-topic for time-nuts. A couple
of delayed postings from the queue will follow. But please, lets not go
Would someone be a hero and record the raw subframe data from GPS today? It's
only 50 bits per second (that's about 8 bytes/second) per SV.
A select few GPS receivers have binary commands that return this low level of
detail: M12 (@@Tr), SiRF (8), uBlox (RXM-SFRB).
My attempts to pull this off
Thanks to that Pulsar / Garmin thread some weeks ago I happened to be
continuously logging serial/USB NMEA data from a Garmin 18x receiver.
The PGRMF sentence was enabled. This Garmin-unique message reports both UTC
date & time as well as GPS week & second. It's a very nice feature. As
Last week John W mentioned that he has a vintage FTS 4040 cesium standard for
sale on eBay.
Taka K and others were asking about power supplies and interior photos.
So I grabbed one from storage that already had the covers removed:
http://leapsecond.com/museum/fts4040/
If anyone has questions
BobH wrote:
>> This would be an excellent project for time-nuts to verify. First, a
>> better explanation of John Harrison’s method is in order. A vertical
>> window edge is not sufficient - a second vertical reference at a
>> distance is required - Harrison used a chimney on a neighbor's house.
I received the following email and permission to post it on time-nuts:
> Hello,
>
> I am the executive editor of the IEEE's flagship magazine, IEEE Spectrum.
> I recently acquired a TAPR "Pulse Puppy" and I am intrigued by the idea of
> using it to build a very precise clock that I would share
> Hi Everyone,I like to know if it possible to run let say 10 GPSDO, 16 Rb clock
> together and take the average to control 1 "master clock" and have better
> stability ?
> like what BIPM or NIST doing.
> I have search about ensemble system but I have no idea how much advantage
> I get from some
> Just a basic question for an application with low accuracy
> requirements. I only need an accuracy of +/- 1 ms on the 1 PPS signal.
>
> Does anyone have any data on the behaviour of a Garmin GPS 16 HVS (or be
> able to point me in the right direction to find such data) w.r.t. the 1
> PPS
> Does anyone have any data on the behaviour of a Garmin GPS 16 HVS (or be
> able to point me in the right direction to find such data) w.r.t. the 1
> PPS output when a valid fix is not available.
We had suspended this thread because it was going off on a tangent. Later there
will be a
> Christopher Shawn McGahey's wrote his phd at Georgia Tech on the subject,
> and it sorts a lot of facts from fiction.
"HARNESSING NATURE'S TIMEKEEPER: A HISTORY OF THE PIEZOELECTRIC QUARTZ CRYSTAL
TECHNOLOGICAL COMMUNITY (1880-1959)"
>> https://www.nist.gov/news-events/events/2019/06/2019-nist-time-and-frequency-seminar
>
> Mother of God, John, what makes this meeting worth the price?
Hi Bill,
Yes, it sounds high but perhaps not out of line for multi-day professional
conferences / seminars these days. True, you have to
Bob,
> is this just a known routine bug
Yes, known. Yes, routine. No, not a bug.
GPS system time is kept as a 10-bit week number and 20-bit second number. The
seconds count from 0 to 604799 and the week counts from 0 to 1023. What this
means is that every 1024 weeks (approx 19.62 years) there
FYI
- Original Message -
From: U.S. Coast Guard
To:
Sent: Monday, January 28, 2019 11:16 AM
Subject: CGSIC Bulletin: GPS Testing Notice Concerning the GPS Week Number
Rollover
All CGSIC,
GPS Testing Notice Concerning the GPS Week Number Rollover
The Global Positioning System
> Being a bit new to HP (only 35 years), I never head of Dymec before.
This web page gives the best coverage of Dymec that I've seen:
http://hpmemoryproject.org/news/dymec/dymec_page_00.htm
You'll recognize much of that era's test equipment.
Also near the end are many photos showing the dy
Bert,
That looks like a very nice board. Thanks for posting. Let us know how to
obtain one; as board, kit or product.
/tvb
N.B. The original posting was aol / html. It has been reformatted below to work
with the time-nuts server.
- Original Message -
From: ew
To:
Thanks much, Corby, for the warning. For those of you wondering about item
number(s):
"Hewlett Packard HP 5065A Rubidium Vapor Frequency Standard"
https://www.ebay.com/itm/Hewlett-Packard-HP-5065A-Rubidium-Vapor-Frequency-Standard-/123599926670
Ended: Jan 18, 2019 , 6:55AM
"Hewlett Packard HP
Mike, Attila, Rick,
> Which caesium beam standards were available in 1956?
The Atomichron, made by the National Company. This was the first
commercial cesium standard; about 50 were made. Attila, you saw one at
my house when you visited last year. It's about 7 feet tall. The one I
have was
Hi Eric,
> 2. Date/time stamps in the data shall be rounded to the nearest EVEN
second by the system instances
That's a clever way to both mask accuracy & uncertainty and to avoid
leap seconds. Still, it smells like a hack, unfit for the 21st century.
But I feel your pain.
BTW, this is
Chris,
If your data set is small enough (e.g., less than 40,000 points) so that all
the tau are 4 digits or less then Stable32 will use plain integers in the
little tau+sigma box inserted into the ADEV plot. For non-integer tau, or data
sets that result in tau values 1 or greater,
Dan,
I hate to speculate but it's really odd that more than one person is
reporting EFC issues with the Z3801A this week. I wonder if it's a bug
in the Motorola Oncore; the OEM GPS receiver used in the Z3801A (and
other early hp GPSDO). Two events have happened recently:
1) There was a GPS
Hi Dana,
Can you explain more what you use a GPSDO for? For most people a GPSDO
is merely a replacement for a stand-alone XO or TCXO or OCXO or even
rubidium. As such, the more stable and accurate the frequency the
better. Which is why a FLL-based GPSDO, as Leo describes, is a perfectly
fine
>
https://www.microsemi.com/product-directory/active-hydrogen-maser/4123-mhm-2010-active-hydrogen-maser
Corby,
Did you notice a week or two ago there's an updated version:
https://www.microsemi.com/product-directory/active-hydrogen-maser/5548-mhm-2020-active-hydrogen-maser
There are links to
Thanks Perry for that offer. I think the PDF is available several places
on the web, including the author's own website:
https://www.its.caltech.edu/~atomic/publist/tempcontroller.pdf
In addition there's a "comment on" the paper here:
Let's put the Bert vs. Dana misunderstanding aside.
To me the key feature in Bert's photo is the Dallas/Maxim digital delay
chip. Look carefully and see the DS1023-50, which is an 8-bit
programmable delay line (~0 to ~127 ns in 0.5 ns steps). This is a
technique used to remove sawtooth error
> I'm just curious if the phase difference slope value can be plugged
in to this equation.
> I'm seeing 4.22E-12 as the slope value in the upper right of the
> TimeLab phase difference plot. Is that telling me that my DUT is
> within +4.22ps / sec from my reference 1PPS for the 24 hour
>
Bob,
Several of us do long-term measurement of mains frequency. We tend to
time-stamp cycles and then compute period or frequency, rather than
measuring frequency or period directly. Traditional counters in gated
frequency or time interval mode have dead time and this will skew results.
In
> There's another relatively simple clue in the old GPS signal: the leap
> second count! A device manufacturer could teach it what the leap second
> count was at manufacturing time, and how to predict a lower bound on the
> leap second count in the future (with a suitable safety margin / fudge
>
If you don't like to click on encoded URL's or don't trust box.com,
The original source of the PTTI paper:
Zero-Crossing Detector with Sub-Microsecond Jitter and Crosstalk
https://tycho.usno.navy.mil/ptti/1990papers/Vol%2022_20.pdf
Another trusted source:
Zero-Crossing Detector with
There was an informative thread back in 2005 on the topic of hp 5370A
vs. 5370B:
https://www.febo.com/pipermail/time-nuts/2005-April/018053.html
It's worth reading the entire thread, or at least, read the reply by JJ
(from Agilent T):
An email came in asking if it was possible to improve the performance of
a TCXO if one monitors the temperature of the PCB or enclosure and then
applies timekeeping corrections in s/w based on that data. I don't have
specific P/N or other details so treat this as a generic question. Has
anyone
seem to have been sold; I'm hoping one or two of them were to
time nuts reading this.
Thanks,
/tvb
On 7/26/2019 12:02 PM, Tom Van Baak wrote:
Yes, I'm evaluating a FSA3011 at the moment. It's a cute little unit. > Documentation is sparse, the jpg plots are fuzzy, "customer" supp
is there a comparison of the key characteristics of these two sub-assembles?
The newer 10811 works in older 10544 instruments but not the other way
around; the reason is the additional power supply requirements of the
10544. See the data sheets for the 10544 and 10811:
Chris,
I'll post photos of my Trak 8810 if it will help with your restoration.
Yes, it contains a Magnivox MX 4200 OEM GPS receiver with serial
interface and 1PPS via SMA connector.
I fired up the 8810 for the first time since maybe the late 1990's and
after about 20 minutes it's tracking 6
Roy,
In the early days of time-nuts and eBay the URQ-10A (made by FEI) was
highly sought after due to its reputation for superb stability. There's
also the -23A which is similar but has a frequency drift compensation
feature.
With any old piece of gear it's hard to know if a specific unit
Yes, I'm evaluating a FSA3011 at the moment. It's a cute little unit.
Documentation is sparse, the jpg plots are fuzzy, "customer" support is
nil, but it works. My initial tests show it's ~4x worse than the data
sheet claims but it turns out the unit is quite dependent on the rise
time and
It might be a bit of an over-simplification to split oscillators in
those two camps, "fixed" and "agile". There are often many trade-offs in
performance that you have to deal with. Moreover if you are getting your
oscillators from eBay, or especially parts from China, you may also have
to
I'm pretty sure you can still buy a new Cs tube for a hp 5071A. But the
price is several tens of thousands. I've not found anyone selling
replacement tubes for all the older Cs standards. Treat it like a
ballpoint pen. It will end some day and you can't refill it. Worse, you
can't really tell
Jim,
With N oscillators involved: look for papers about clock ensembles and
time scale algorithms.
The 3 corner hat method, where you create a fictitious mean of 3 clocks
and then compute the deviation of each real clock from the virtual mean,
is just like a simple unweighted 3-clock time
> I hope some will accept the technical challenge of gathering data --
which is fairly minimal.
Andy,
It may have been before you joined time-nuts, but some years ago we
compared mains phase/frequency between Albuquerque, NM and Seattle, WA,
which in spite of being some 1500 miles apart are
https://www.electronicdesign.com/analog/whats-all-p-i-d-stuff-anyhow
For all Bob Pease fans: there's a fabulous 9 volume ~1200 page scan of
his columns here:
https://archive.org/details/Bob_Pease_Lab_Notes
The P-I-D article Ben mentions appears in volume 2, starting on page 167.
/tvb
Martyn,
> I'm always being asked to provide equipment that can produce two 1
> pps outputs aligned to each other to within a few ps.
They should look at their best 1PPS on a 'scope. You can get ns with
care; I doubt ps is possible. I mean, that's THz BW isn't it?
Can you share with us what
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