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

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

Re: [time-nuts] 5950 Crystal impedance meter manual

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

Re: [time-nuts] 4046 replacement

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

Re: [time-nuts] Dual GPSDO - any advantage?

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,

Re: [time-nuts] Weird Stuff WareHouse shutting down

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:

[time-nuts] Timestamping audio waveforms

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

Re: [time-nuts] WWV/CHU

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

Re: [time-nuts] Need a Watch Recommendation

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.

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

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

Re: [time-nuts] Beware the Casio WaveCeptor analog watch

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

Re: [time-nuts] CSAC Project(was CSAC purchase)

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

Re: [time-nuts] Down-conversion to IF and sampling

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

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

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.

Re: [time-nuts] Simple open source microcontroller solution to tune DDS needed

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,

Re: [time-nuts] Trimble Mini-T Timing Glitches

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

Re: [time-nuts] Performance verification for time counters

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

Re: [time-nuts] Allan variance by sine-wave fitting

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.

Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

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

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

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

Re: [time-nuts] Designing an embedded precision GPS time

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

Re: [time-nuts] inexpensive, black box, GPS or NTP based TTL time capture?

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: > > > > >

Re: [time-nuts] Weird GPSDO behavior - update

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

Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

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

Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

y 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>

Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

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

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

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.

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

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

Re: [time-nuts] unknown GPSDO

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

Re: [time-nuts] Papers on timing for lunar laser ranging

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

Re: [time-nuts] PI Zero W LED Desktop Clock with 10ths of Seconds / NTP disciplined

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

Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

017, 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 Ander

Re: [time-nuts] Hints on PPS Buffer design...

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

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

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.

Re: [time-nuts] poor-man's oven

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

Re: [time-nuts] Next Aug 21 eclipse and time flow --> WWV carrier phase

ally 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 ju

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

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

Re: [time-nuts] LPFRS phase ripple?

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

Re: [time-nuts] Looking for info on Trimble 16634-10

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

Re: [time-nuts] Machining some aluminum help!

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

Re: [time-nuts] GPS seconds conversion on an Arduino

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

Re: [time-nuts] time.gov

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

Re: [time-nuts] Looking for a HP-58503 display

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

Re: [time-nuts] Using 5335 frequency counter for timing

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

Re: [time-nuts] Frequency counter questions

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

Re: [time-nuts] Name of integral of timing residual

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

Re: [time-nuts] TAPR TICC boxed (input protection)

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

[time-nuts] 32768Hz oscillator using AT-cut crystal

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

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

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

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

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,

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

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

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

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

Re: [time-nuts] Antique precision timing device without electronics

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, >

Re: [time-nuts] Bye-Bye Crystals

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

Re: [time-nuts] Coming to a drive-way near you: Optical Lattice clocks

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

Re: [time-nuts] advice

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: > >

Re: [time-nuts] Vintage Frequency Measurement

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

Re: [time-nuts] Thermal effects on cables

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:

Re: [time-nuts] purpose of time of day display units

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,

Re: [time-nuts] purpose of time of day display units

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

Re: [time-nuts] wifi with time sync

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

Re: [time-nuts] EFOS2 MASER turns 34!

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,

Re: [time-nuts] EFOS2 MASER turns 34!

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

Re: [time-nuts] Line Voltage - USA

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

Re: [time-nuts] 1PPS users?

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

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

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

Re: [time-nuts] GALILEO online: any changes seen?

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

Re: [time-nuts] Time math libraries

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

Re: [time-nuts] UCCM GPSDO

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 > >

Re: [time-nuts] Switching regulator replacement for 7805

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

Re: [time-nuts] Switching regulator 12 > 4 V (3.3)

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

Re: [time-nuts] Audio format with embedded timestamps?

rd 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

Re: [time-nuts] Is there any Ubuntu/Linux Software for the Z3801A?

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.

[time-nuts] Audio format with embedded timestamps?

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

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

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

Re: [time-nuts] Thermal impact on OCXO

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

Re: [time-nuts] Secondary phase noise standard & FE405

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

Re: [time-nuts] Thinking outside the box a super reference

> 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

Re: [time-nuts] Thinking outside the box a super reference

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

Re: [time-nuts] Man with too many clocks.

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:

Re: [time-nuts] eLORAN on the air for 30 days

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

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

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

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

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-nuts] MM5314 remote setting

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

Re: [time-nuts] Atomic Watch

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

Re: [time-nuts] leontp offset?

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

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

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

Re: [time-nuts] Need Time Help

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

Re: [time-nuts] Jim Miller simple GPSDO

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

Re: [time-nuts] A new take on the all-hardware GPSDO concept

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

Re: [time-nuts] What's the best Windows 10 ntp client?

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

Re: [time-nuts] Safely getting the electrical length of a connected antenna feedline

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

Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

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: > >

Re: [time-nuts] The home time-lab

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

Re: [time-nuts] The home time-lab

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,

Re: [time-nuts] Cable length calibration

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,

Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

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

Re: [time-nuts] How to get unknown frequency quartz crystals oscillating

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

Re: [time-nuts] How can I generate a very clean 1 W signal @ 116 MHz ?

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

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

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

Re: [time-nuts] patents and hobbyist projects (was: Temperature controlled TCVCXO)

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

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