Re: [time-nuts] Affordable PoE 6-digit time displays?

At work we have POE LED clocks, I think 2.5", circa $400-$500. So your $300 price you've been seeing is about right. In terms of homebrew: I bought a bunch of 3.5" high green Seven-segment displays 10+ years ago. Cheap, really cheap at the time! Was always intending to build a 6-digit clock with

Re: [time-nuts] time-nuts Digest, Vol 168, Issue 21 SDRs and precision time

I thought the thinned array curse was specifically referring to transmitting coherent arrays? In terms of synthetic aperture receiving arrays, I'm not sure the absolute timestamping accuracy you can extract from say, the on-off encoded minute marker on the 60kHz reference signal will be good for m

[time-nuts] Bicentennial GOES satellite clock

See the groovy picture at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4847573/figure/f9-j110-2lom/ If anyone knows the whereabouts or history of the bicentennial GOES time clock display, please let me know! Tim N3QE ___ time-nuts mailing list -- time-n

Re: [time-nuts] Bicentennial GOES satellite clock

> "Satellite Controlled Digital Clock System (patent)" > https://tf.nist.gov/general/pdf/1791.pdf > > "A Satellite-Controlled Digital Clock (NBS TN-681)" > https://tf.nist.gov/general/pdf/452.pdf > > /tvb > > > - Original Message - > Fr

Re: [time-nuts] Loss of NIST transmitters at Colorado and Hawaii

While consumer WWVB clocks are widespread today, almost all (or all) professional clock displays have shifted to NTP over copper or over sometimes WIFI in the past decade. WWVB or WWV, without an external antenna, was never a good choice for a clock in a steel building to begin with. 30 years a

Re: [time-nuts] 1PPS for the beginner

With a scope it is super easy to look at PPS pulses that are microsecond to a few milliseconds wide and tell you are triggering on the "leading edge". Harder to decide at 50% duty cycle especially if you think it might have been inverted along the way (almost all buffers are inverting). Of course

Re: [time-nuts] WWVB Chronverter update progress

The consumer WWVB wall clocks use a single 60kHz crystal as a front end filter (not as an oscillator). Unloaded Q of a small tuning fork crystal is often 30,000 or so. (You can actually observe this order of magnitude when a 32kHz crystal used in an oscillator - remove power and the crystal contin

[time-nuts] WWV/WWVB in NTP surveys

Some stats in historic NTP surveys show that WWV and WWVB based refclocks were relevant 20+ years ago: 1997 - Mills survey - 47 GPS and GOES vs 74 WWV and WWVB. 1999 - Minar MIT survey - 129 GPS and GOES vs 24 WWV and WWVB. In those two years it is pretty obvious the world was swinging from LF a

Re: [time-nuts] Oscilloscope-based measurements of frequency stability

Dana, the short term few-ns jitter of the two phases, I think in a digital instrument is most likely data acquisition glitches. Even on a good old analog scope, jitter in the trigger circuit or jitter in amplitudes (with resulting changes in harmonic content and thus the shape of the curves) can c

Re: [time-nuts] new WWVB BPSK dev board

Thanks for the heads up Tom! I ordered one and if it comes before the end of the year I may have some time over the holidays to do acquisition test from Maryland and maybe some cross-comparison with GPS PPS. Here in Maryland I have somewhat unreliable reception on commercial non-BPSK WWVB clocks a

Re: [time-nuts] new WWVB BPSK dev board

Because of the Q of WWVB's transmit antenna (at least 300 by my back of the envelope estimates), I don't think we could ever claim a WWVB PPS edge sharper than 5 milliseconds and that might be optimistic. Tim N3QE On Tue, Dec 4, 2018 at 11:49 AM Bob kb8tq wrote: > Hi > > The I2C clock rate is g

[time-nuts] ES100 BPSK WWVB jitter data

I let the Universal Solder ES100 board run overnight in my basement in Maryland for 10 hours, its little loopsticks at least 5 feet from switching power supplies, and it often could get successful WWVB BPSK decodes. This is a feat in itself. No non-BPSK WWVB clock antenna has ever produced a usefu

[time-nuts] Linear or quadractic fit algorithms for small microcontrollers?

I know we discussed this many years ago, probably in context of the HP Smartclock patent, but I've forgotten all the details. Say I have a circular buffer of up to several dozen time and offset values. The intent was to sample at regular intervals but some samples are missing. Are there simple mic

Re: [time-nuts] Linear or quadractic fit algorithms for small microcontrollers?

0 tracking attempt will return as a claimed success BUT it is off by way more than 100ms, often by an integer number of seconds (say 1-3 seconds). Tim N3QE On Thu, Dec 27, 2018 at 7:24 PM Magnus Danielson wrote: > Hi Tim, > > On 12/26/18 4:53 PM, Tim Shoppa wrote: > > I know we

Re: [time-nuts] Misuse of word "decimate" (was Re: Short term 10MHz source)

This is not misuse. Everyone in signal processing knows what decimation means in this context. I pulled out one of my older signal processing books - Gold and Rader, "Digital Processing Of Signals", 1969 - and Decimation is used in several places exactly as we use it today. I looked in some of my

Re: [time-nuts] Portable Time Standard

Many of the 70's/80's Japanese marine quartz chronometers had a test button that gave you an audible beep every second. I am not an expert in every quartz clock mechanism BUT a 1-10mH nonshielded inductor makes an excellent pickup for the "ticks" from any quartz clock or watch that I've ever met.

Re: [time-nuts] PPS clock module

Some of the 1970's era National Semiconductor clock modules and chips, you could leave the 50/60Hz input unused and instead jam a PPS pulse into the "colon blink" pin. There were some commercial time display products into the 1990's that used this and other NatSemi clock tricks. For example where

Re: [time-nuts] Auto-fail-over switch

Do you have any phase continuity requirements? Do you need to failover if the input is 9MHz or 9.99MHz instead of 10MHz? If not then any carrier-operated relay will do it. Tim N3QE > On Feb 4, 2019, at 9:26 PM, Jeff Blaine wrote: > > Wondered if anyone had seen some sort of gadget that w

Re: [time-nuts] GPS Weekly Rollover Fail

This will be my Z3801A's second rollover and its third 1024-week epoch. Is there any pre-1980 GPS equipment still out there that will be undergoing a third rollover and fourth 1024-week epoch? Was the 1978-1979 Block 1 GPS usage, using a different base date, or were there more fundamental changes

Re: [time-nuts] 4.19 MHz xtal

2 to the 22nd power is 4.194304MHz. 32768 Hz crystals are a tuning fork cut with a very different temperature curve than a typical AT cut which your 4.19MHz crystal probably is. Tim N3QE On Sun, Mar 31, 2019 at 6:03 PM Neville Michie wrote: > Hi, > I have a Philips quartz clock that runs on 4.

Re: [time-nuts] WWVB Disciplined Oscillator

Wayne, there was a superb 2015 QEX article by KD2BD on his WWVB disciplined frequency standard. Full article is online here: http://www.arrl.org/files/file/QEX_Next_Issue/2015/Nov-Dec_2015/Magliacane.pdf As a frequency standard I have no major disagreement with the PTTI article. But the 100 micros

Re: [time-nuts] Garmin GPS12XL V3.51

Beyond the predictability of physical variation, there is also the unknown probability of a human decision to abolish leap seconds, while also continuing to satisfy the various legal requirements around the world that civil time be tied to the Sun. https://en.wikipedia.org/wiki/Leap_second#Proposal

Re: [time-nuts] Amazon AWS time sync service

Long-term there is no drift to measure between regions. With each region on its own GPS receivers and atomic clocks, it seems much more likely that anything you measure will be asymmetries in network delays between regions. Note that like Google has since 2008, AWS "Time Sync" also smears out leap

Re: [time-nuts] Cloudflare

I have been observing time.cloudflare.com latency and accuracy the past 3 days. It is a stratum 3 server, so folks might think that it's not as good as a Stratum 1 or Stratum 2. BUT... it has exceptionally low latency and it seems very likely it's Stratum 3 because it is fed by a well-maintained

[time-nuts] ES100 suddenly more sensitive in summer!

Interestingly enough, compared to my initial testing last winter, my ES100 is suddenly much more likely to acquire and track WWVB in broad daylight. This morning it is acquiring from a cold start almost every time. (The "bad minutes" of course still don't work). Most likely reason would be some r

Re: [time-nuts] 60 Hz frequency and phase measurement

Jim, most of us are satisfied to use a 6.3VAC filament transformer to step down from 120VAC and isolate from the power line. Tim N3QE > On Jul 2, 2019, at 5:56 PM, jimlux wrote: > > There's some designs on the list (using a PICPET, for instance) to measure > the local line frequency and phase

Re: [time-nuts] 60 Hz frequency and phase measurement

Jim, almost any mains powered lighting has a substantial 120Hz component in light intensity. It's quite reasonable to trigger off this at nighttime if the light is on and only that single light is in field of view of a phototransistor (no car headlights allowed to come into view!) It's still far f

[time-nuts] ES100 WWVB clock notes

After some initial evaluation in December last year, I've done some more work and prototyping with the ES100 WWVB chip+board from Universal Solder in various clock applications. Most of my work uses an Arduino Nano for processing. What I like is that the ES100 puts out data in UTC, which is a litt

Re: [time-nuts] Noob question, NTP stratum 1.

Real ntpd uses a drift file to track the local processor's frequency offset and has a good estimate of processor clock drift after a day of tracking. The Raspberry Pi processor clock, like any motherboards', will often be off by off anywhere from +/-200ppm but the good news is that it usually vari

Re: [time-nuts] atomic/chemical THz sampler

Kind of the opposite of what you are asking: ultrafast laser spectroscopy is used to study chemical reactions and make measurements of their time scales (often in the time range of several femtoseconds). And precise timing of photons produced is critical to making the measurements. The chemical pr

Re: [time-nuts] Serial or other simple protocols for exchanging time

Bob, ntpd for ages has supported broadcast/multicast UDP. https://www.eecis.udel.edu/~mills/ntp/html/assoc.html#broad If you care about security it's like a bag of angry cats. And the one-way-ness removes the ability to measure round-trip delay. So it's pretty rare to see it being used well. Tim

Re: [time-nuts] 5 Mhz to 10 Mhz and 25 Mhz

Don, don't worry too much about soldering the 8-pin SOIC's. You've been soldering 0.05" pitch TO-92's for decades. And each 4-pin side of a SOIC is 0.05" pitch as well. Rather than use an adapter with perfboard, I'd advise going with dead-bug with all grounded SOIC pins going straight to copper PC

Re: [time-nuts] Capturing NMEA and TICC timestamp data in time-correlated way?

In Unix there is the "ts" (aka timestamp) command will be a good start as long as you have newlines (pure NMEA has CRLF at the end of each line but I've come across devices that use other variations). http://manpages.ubuntu.com/manpages/trusty/man1/ts.1.html e.g. I like to use the "%.s" format for

Re: [time-nuts] 10811-Parts... (Using the thermal regulator circuitry)

I understand several of the modern MEMS OCXO's use microcontroller PID control for the temperature, avoiding the need for any large capacitors for compensation. The microcontroller does a lot more than the heating job, judging by the PhD thesis I see coming out of China. They seem to feed-forward

Re: [time-nuts] NTP apps on Windows question

My feeling is that if you do not have competing applications fighting for control of the clock, and your clock time is visibly correct to a second, that your problem is not the system time. Meinberg ntpd by default disables w32time but it may not disable other applications (you mentioned a few of

Re: [time-nuts] DC distribution

I want to recommend Anderson Powerpoles for DC distribution too. A trillion times better than all the incompatible molexes. And those West Mountain Radio multi fused splitters are exactly what you want for splitters. In addition to the WMR splitters, bare PCBs for building up your own are avail

Re: [time-nuts] Do ordinary clouds adversely affect GPS reception?

I don't think clouds is the direct cause, but of course clouds in the sky can be correlated with wet foliage. Especially if the GPS Field Of View has a lot of angle taken up by tree canopy, wet foliage can substantially degrade not just GPS reception but other VHF and UHF signals. I notice this t

Re: [time-nuts] Lowest Power NTP Server

ESP8266 as a simple UDP server is 50mA * 3.3V = 0.17W. Tim N3QE On Sun, Dec 1, 2019 at 12:22 PM Bob kb8tq wrote: > Hi > > If you are going to run the beast on batteries, and talk to it via WiFi, > what’s the lowest power > NTP server you can build? Timing source to keep it under a few ms would

Re: [time-nuts] Lowest Power NTP Server

Didier, I'm not sure I saw Bob write that 5uS was his goal. I don't think anyone would claim that ordinary cheap WiFi can achieve consistent sub-millisecond variations in latency. Tim N3QE On Sun, Dec 1, 2019 at 5:06 PM Didier Juges wrote: > You should look at latency. The ESP8266 has serial (

Re: [time-nuts] Lowest Power NTP Server

e two :) Happens when doing two things at once... > >> Anyhow, I mentioned it because I did do some experiments early on the > >> ESP8266 and the seemingly random flash reload was quite unexpected. It > was > >> in the 10's of uS if I recall, so of course not a rea

Re: [time-nuts] Lowest Power NTP Server

from 192.168.1.13: icmp_seq=21 ttl=255 time=0.777 ms 64 bytes from 192.168.1.13: icmp_seq=22 ttl=255 time=0.880 ms On Mon, Dec 2, 2019 at 9:56 AM Tim Shoppa wrote: > Bob, I find that 2.4GHz Wi-Fi UDP latency with ESP8266 will frequently be > tens of milliseconds and is never/rarely cons

Re: [time-nuts] IERS leap second bulletins?

The official URL is ftp://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat In the past years a couple of my frequent workplace locations, have begun blocking all non-secure protocols (HTTP and FTP included). Even before that, many firewalls were not set up properly to handle the FTP protocol. I’m goi

Re: [time-nuts] signal transit time through WWV receiver

I can tell you, that with say a 10kHz bandwidth AM receive filter on an analog receiver, the transit time through that filter will be ballpark 100 microseconds. Possibly more if it's a high-order filter. I have used DSP-based (non-PC) SDR's for WWV reception and characterized them as you suggest.

Re: [time-nuts] Cesium Mechanical Chronometer

Historically they would have tracked any deviation between the chronometer and radio standards by updating the rate card, and only rarely adjusted the chronometer time or rate itself. I would suggest a more interesting project, is to monitor the ticking of the Chonometer vs your CSAC (possibly aco

Re: [time-nuts] GPS location inaccuracies from a cell phone

Cellphones in use in urban canyons or places with foliage will have substantial GPS signal losses. Mapping programs hide this by using algorithms that guess you are continuing to move along the same street at the same speed. e.g. just slightly smarter than dead reckoning. It will always try to sna

Re: [time-nuts] Ublox timepulse

freqPeriod is in microseconds up to 2^32 so you ought to be able to set it to 60,000,000 and get one pulse a minute. If you set alignToTow will align it to the top of second but not top of minute so you'd have to parse the UTC timestamp and use it to "start" the 60 second cycle at the correct seco

Re: [time-nuts] GPSDO that isn't GPS locked for large time scales?

Many of the Chinese E-bay GPSDO's are frequency-locked, not phase-locked. I believe yours in question, is frequency locked. The seller's description certainly shows that his only goal was frequency and not phase. Sometimes I joke to Tom that maybe we should call this list "phase nuts" and not "ti

Re: [time-nuts] GPS module recommendation for Pi timing

If your product depends on monotonic times, there are a lot of good reasons for using NTPD. It will slew the clock rather than jump it which can be hugely important for many applications if there is some need for data to be accumulated with monotonic timestamps. It will also apply good drift correc

Re: [time-nuts] Power glitch - Sat morning

Hal, were there any storms or maybe just drenching rain in your area Saturday AM? Fallen trees, drooping branches, and line crosses all go together. 5 seconds is a very common value for circuit breaker reclosers as faults either clear themselves or are isolated. Tim N3QE On Tue, Mar 31, 2020 at

Re: [time-nuts] Buffer amplifier, OP Amp, vs MMIC, vs discrete?

Tobias, are you talking about the Wenzel AF Preamp that uses paralleled JFET's? That uses a 2SK369 JFET which is actually still in production and distribution and commonly available in TO-92 even. (Contrast with J310 which was once pure jellybean but today no longer made new in TO-92!!!) Tim N3QE

Re: [time-nuts] power supplies

Jim, when it comes to "bench supplies" - knobs for voltage and meters - most of the commonly available Chinese bench supplies in the under 3A-range are linear with series regulator. This unit (HY1803D) is typical and has a transformer (relay-selected winding depending on the voltage setting) and a

[time-nuts] Any time-nuttery for spring-wound car clocks?

Has anyone done any time-nuttery with the mechanical clocks available in cars up through the 1970's? These were typically spring-wound mechanisms with a solenoid that winds the spring when it approaches wound-down condition. I can find some good articles on the interwebs about reconditioning and

Re: [time-nuts] Any time-nuttery for spring-wound car clocks?

could be picked up microphonically or magnetically to do non-interfering measurements. Tim N3QE On Mon, May 4, 2020 at 1:26 PM Warren Kumari wrote: > On Mon, May 4, 2020 at 11:37 AM Tim Shoppa wrote: > > > > Has anyone done any time-nuttery with the mechanical clocks available

Re: [time-nuts] Any time-nuttery for spring-wound car clocks?

On Mon, May 4, 2020 at 11:56 AM Richard (Rick) Karlquist < rich...@karlquist.com> wrote: > On 5/4/2020 8:36 AM, Tim Shoppa wrote: > > Has anyone done any time-nuttery with the mechanical clocks available in > > cars up through the 1970's? > > > > My experienc

Re: [time-nuts] Quick check of a GPS controller oscillator

Bob, your list isn't bad, but it completely misses the point whether the lock is phase-lock (certainly what anyone in telecom trying to lock a wide network would expect) or frequency-lock (like some BG7BTL's and probably some other Chinese clone cobbled-together units). A large chunk of hobbyist u

Re: [time-nuts] Interesting application for really nutty timing

Hal, at one point shortly after their discovery in the late 60’s, Pulsars were considered as a possible primary frequency standard. Then atomic clocks became more amenable as lab standards. As to time-nut measurements on pulsars, check this out: https://arxiv.org/abs/0909.1054 Millisecond and

Re: [time-nuts] ThunderBolt question

Many of us use F connectors and 75 ohm CATV RG-6 coax for GPS antennas when both antenna and receiver are specified for 50 ohms. Don't sweat the difference between 75 and 50 ohms. Tim N3QE On Fri, Jun 5, 2020 at 7:22 PM Robert DiRosario wrote: > I have a Trimble ThunderBolt GPSDO that I just r

Re: [time-nuts] Frequency division by 81

Depending on your needs there are many off-the-shelf programmable frequency divider IC's. Most of the modern ones are not programmed by strapping pins but by serial connection to a microcontroller so this may not be your cup of tea. If so, look at the math and note that 81 = 9*9 or 3*3*3*3. Two

Re: [time-nuts] Vibration isolation of quartz oscillators

Damping at time constants of a fraction of second or longer can be done with shock absorbers which are usually some form of dashpots filled with viscous fluid or gas. In the industry I work in we often use airbag suspensions up to time constants of several seconds. I might guess that most vibr

Re: [time-nuts] Raspberry Pi NTP server

Andrew, outlier rejection in NTPD is not the most stable thing in the world. You have two local refclocks that are consistently 200ms off from the "rest of the world" and this is 10 times larger than the round trip delay to the rest of the world. But the local stratum 0 refclock poll interval is

[time-nuts] For those following ES100 WWVB receiver modules

The ES100 module sold by universal-solder.ca which Tom introduced us to a couple years ago, is now End-Of-Life. "A new module is currently in development". https://www.universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/ I myself did some experimenting wit

Re: [time-nuts] eLORAN will be on the air GRI 99600

Transit 5B-5 (from 1965) is nuclear powered and still transmitting. Nobody has any idea how to pull out the time code, though! https://twitter.com/coastal8049/status/1260802699051692033 On Thu, Aug 6, 2020 at 4:43 PM jimlux wrote: > On 8/6/20 9:17 AM, Taka Kamiya via time-nuts wrote: > > Someon

Re: [time-nuts] 5 Digit Panel meters

This all probably belongs on volt-nuts not here. But 16 bit ADS1115’s are common as dirt for a few bucks and will yield most of 5 digits of monotonic non-skipping counts. The internal reference and programmable gain of the ADS1115 is 0.1% ballpark. So any implication that all 5 digits are accur

Re: [time-nuts] Oscilloquartz BVA has been sold. Thank you all who expressed an interest.

Bill, most modern double-oven OCXO's (including I think the BVA under discussion) are under 5W average consumption after warmed up. Most UPS's are rated for near-peak-power output (most of a kW or more) for 5 or 10 minutes to give time to shut computers down gracefully and are not sized well for k

Re: [time-nuts] More ES100 / WWVB BPSK chips

Thanks to Tom's heads-up, I ordered a new style ES100 set with breakout board from Universal Solder 13 days ago, and it arrived today. The pinout documentation zip package from Universal-Solder website, (which was mighty confusing to begin with), still seems to describe the original board. But the

Re: [time-nuts] WWVB Dephaser Question

The NIST WWVB transmitter antenna is very massive and very well documented: https://apps.dtic.mil/sti/pdfs/ADA299080.pdf For receive on VLF there is no reason to go so big. A short whip produces plenty of atmospheric noise so there’s no purpose at going bigger. A loop (including ferrite core lo

Re: [time-nuts] La Crosse Clocks -

I have bought several of the ES100 breakout board kits from Universal Solder and rolled my own 24 hour LED clocks (UTC, of course). I don't know of any "smart" 24 hour analog movements with self-aligning hands like the LaCrosse 12-hour analog. There are plenty of 24-hour impulse stepper clock move

Re: [time-nuts] Rebroadcasting time signals [WAS: La Crosse Clocks - ]

Presumably any "rebroadcast" of WWVB is done in the spirit of near-field communications where any far-field radiation falls off like 1/r^3 from a small inductive transmitter loop. A loop the size of your entire house would be "small" in terms of 60kHz wavelength. Unintended coupling of the 60kHz

Re: [time-nuts] "Q for dummies"

Just two sentences is quite a challenge! Maybe one of the two sentences should explain the downsides of a system design that uses filters or networks with high Q. "High-Q filters and matching networks will have circulating currents resulting in poorer efficiency, and higher variation in group and

Re: [time-nuts] Mains Frequency

The classic 70's LED clock used a 60Hz mains transformer and yes it was easy enough to for the solid state electronics count pulses derived from the low voltage secondary winding of the mains transformer. If your appliances are from the 70's or 80's yes it is very likely the LED clock is counting A

Re: [time-nuts] AN/URQ13 reference AT cut crystal?

Magnus, were they trying to use the SC-cut crystal itself as a calorimeter, or something else? if using a crystal as a calorimeter (essentially self-temperature probe) to detect axions, they do not want the crystal cut for stability at operating temperature? You want to operate the crystal where

Re: [time-nuts] Old Crystal.

G3UUR and K8IQY have simple test circuits for measuring crystal motional parameters. G3UUR is great for comparing or matching a batch of similar-cut AT crystals. The K8IQY method is a bit more comprehensive for "unknown" crystals and involves very tiny step sweeping around the resonance you're in

[time-nuts] Re: The Collapse of Puerto Rico’s Iconic Telescope [April 5th, 2021 New Yorker]

I see several parallels between Arecibo's construction vs its actual use, and GPS deployment vs actual use. Arecibo was actually built using ARPA and US Navy funding as a way of conducting ionospheric research - to benefit military communication over radio and develop over the horizon radar techno

[time-nuts] Re: Video of early Cesium clock development

For those interested in the National Company’s cesium clocks, you can google “Atomichron” (their brand name) or check out this Smithsonian archive: https://sova.si.edu/record/NMAH.AC.0547 Tim N3QE On Monday, April 12, 2021, Jerry Steinback via time-nuts <

[time-nuts] Re: Replacement of Windows NTP server with Linux

Ubuntu server is great - I’ve been supporting applications on Ubuntu for over 10 years now and it is easy to maintain and update. Set Ubuntu up absolutely minimally - no packages installed unless absolutely necessary. Certainly no X11 or GUI desktop. This way the number of security updates will be