[time-nuts] mailing list moderation, STATUS, May 2018

FYI -- you may have noticed that earlier this week we turned off time-nuts list 'moderation'. This means postings now immediately go to the entire group and archives without review or delay [1]. So be extra careful about what you post, and also to whom, and how often. When the list is 'open'

Re: [time-nuts] Question about frequency counter testing

Azelio, the problem with that approach is that the more stable and accurate your DUT & REF sources the less likely there will be transitions, even during millions of samples over one second. A solution is to dither the clock, which is something many old hp frequency counters did. In other

Re: [time-nuts] Question about frequency counter testing

> That might be an interesting way to analyze TICC data. It would work > better/faster if you used a custom divider to trigger the TICC as fast as it > can print rather than using the typical PPS. Hi Hal, Exactly correct. For more details see this posting:

Re: [time-nuts] Cheap jitter measurements

Hi Gary, > As requested, here is my raw data: http://pi5.rellim.com/1d.log.gz I'm having a close look. These are quite a few bad data points and that partly explains why your ADEV plots were off. Trim the file at, say, line 71000 and try again; the results will be much better. I'll post an

[time-nuts] nuts about position

List -- I had a recent query by a researcher who would like to pinpoint the location of his telescope(s) within 0.3 meters. Also (he must be a true scientist) he wants to do this on-the-cheap. He may have timing requirements as well, but that's another posting. So I toss the GPS question to

Re: [time-nuts] Cheap jitter measurements

Hi Gary, > A little coding later and there are nice plots. They were compared to > the output of tvb's adev.c program. Results are similar. Whoa there cowboy. That doesn't mean it's right. Comments: > gps.png looks as expected. 1. No, it would appear something is wrong with your data. You

Re: [time-nuts] WWVB information

So Doug's Spectracom WWVB receiver shows a green lock status. I didn't believe it, but he sent a photo. I then tried it here and the same thing happens to me. It's very suspicious because we know these old carrier phase WWVB receivers don't work with the enhanced WWVB broadcast format. Instead

Re: [time-nuts] Pulsars, clocks, and time nuts (Jim Palfreyman)

Amazing news... 1.2.3. 1) Many of you know that pulsars are weird astronomical sources of periodic signals. Some are so accurate that they rival atomic clocks for stability! True, but I don't have a 100 foot antenna at home so I'll take their word for it. Plus, you have to account for a myriad

Re: [time-nuts] WWVB information

I've been talking with Doug to better understand why his Spectracom WWVB receiver shows the green lock indicator. This receiver should not work given the enhanced WWVB modulation we've had since 2012. Fortunately he has chosen not to touch anything while we ponder this. Meanwhile I pulled out

[time-nuts] time nuts overflow / gentle reminder

All -- This is a reminder that time-nuts is a technical mailing list. Please be careful with your replies. If you read, compose and hit send within 30 seconds, it's likely the post will sound like it belongs on social media instead of time-nuts. Our list works best when postings are well

Re: [time-nuts] suggestions on getting 24 Mhz ?

Pete, Is your goal to make SDR frequency measurements? One solution: grab any 24 MHz oscillator you find but use a counter with known accurate timebase (Rb,Cs,GPSDO) to continuously record its actual frequency. Don't adjust the frequency; just record it. Then, apply those readings as

Re: [time-nuts] WWVB Time

> Hi, all of a sudden my Symmetricom comparator/clock has been locking up on > time. > It has been about a week so far. Did they change the code? Anyone else seeing > that? > Doug K6JEY Hi Doug, That would be too good to be true. I asked NIST just now and they report: "We have not changed the

Re: [time-nuts] Cheap jitter measurements

Dan, I wrote a PC-based time-stamping counter (TSC) tool that uses a serial port and QueryPerformanceCounter: www.leapsecond.com/tools/pctsc.exe (Win32) www.leapsecond.com/tools/pctsc.c (source) Give it a try. /tvb - Original Message - From: "Dan Kemppainen"

Re: [time-nuts] ADEV dead time w/ HP 53131A & TimeLab

Dave, > My research concerns oscillator drift on time scales of ~1ms to ~10s, so > I'm guessing the 53131A with its 5-130ms of dead time isn't suitable for > what I'm trying to measure. True. Try a fancy TIA (time interval analyzer) or MDA (modulation domain analyzer) instead. Or consider a

Re: [time-nuts] Cheap jitter measurements

>> Similarly, the box should be able to give me a pulse at a known time. > > how do you set up NTP to do that? Don't know. That's not NTP's job. Any process that can query system time and get/set a GPIO bit will do. The question to be answered is how close to the real time (as in UTC(k), atomic

Re: [time-nuts] Cheap jitter measurements

>>> What do you mean by "jitter" and what do you really want to do? >> I mean jitter as NTP defines jitter. Whatever that is. > > I think you need to figure out what you want to do so you don't fool yourself. > > ntpd is a PLL. There is a low pass filter in the control loop. It will > track

Re: [time-nuts] Environmental sensor recommendations

> Are there any recommendations for other off-the-shelf sensors worth looking > at? Mark, Check out ADT7420: http://www.analog.com/media/en/technical-documentation/data-sheets/ADT7420.pdf A useful white paper, including comparison of NTC RTD and IC sensors:

Re: [time-nuts] Environmental sensor recommendations

Peter, Yes, that's my current favorite turn-key environmental sensor as well. Sure, you can home-brew a slightly cheaper solution. And the Arduino world is full of random sensor examples, which you are free to deploy and debug. But the Sparkfun unit just works; out of the box. From the first

Re: [time-nuts] Harrison's birthday

Jim, The Harrison google doodle is attached for those that missed it [1]. A couple of comments: 1) One alert reader pointed out that the clocks are stopped. Google is capable of clever JavaScript animations, so the least they could do is have the clocks in motion. It would be especially

Re: [time-nuts] Cheap jitter measurements

Hi Gary, One solution is to look for used hp, Fluke, or Racal time interval counters on eBay. 1 or 2 ns is pretty easy to find with a $100 or $200 budget. Look for Racal 1992 or hp 5334B as examples. If you plan to collect lots of data, you'll want GPIB (or RS232 / USB) connections to a PC and

[time-nuts] quartz / liquid nitrogen

Has anyone tried running a quartz oscillator at liquid nitrogen temperatures: -196 C (-321F, 77K)? It's probably impractical commercially, but maybe something of value to a time nut. Would that dramatically lower temperature improve phase noise & short-term performance? Is there a crystal cut

Re: [time-nuts] timing an ITR master clock

Jerry, Most people I know who time mechanical clocks use Bryan Mumford's Microset timer: https://www.bmumford.com/microset.html https://www.bmumford.com/mset/model3.html Bryan has a wide variety of sensors: optical, acoustic, magnetic, laser, etc. Of course it is possible to home-brew a

Re: [time-nuts] Ultralink

> I have a 333 box with 301 antenna. It was a gift several years ago. The > display updates, but the meter never gets off 0. At the time, I thought the > new modulation scheme had killed it and didn't investigate. But tvb > suggested it should still work, so I took the cover off. Hal, I

Re: [time-nuts] WWV/CHU

> This is an IEEE article from 1972 that looks like a good fit: > Nationwide Precise Time and Frequency > Distribution Utilizing an Active Code Within > Network Television Broadcasts >DAVID A. HOWE > https://www.researchgate.net/publication/3092613 FYI: for the

Re: [time-nuts] Ultralink WWVB receiver manuals?

> It would be very nice to have a direct NIST time source in the lab > again, complete with PPS output. If you have a 1200/9600 baud modem and a land line, 303.494.4774 is also a reliable backup source of NIST time.

Re: [time-nuts] Ultralink WWVB receiver manuals?

Congrats on your acquisition. The Ultralink WWVB receivers are very nice. It should still work -- it's an AM subcode (not carrier phase) receiver. If you have more questions let me know. These modules were the darling of precise time at the turn of the century; before mobile phones, before GPS

Re: [time-nuts] Setting correct date on Trimble Thunderbolt receiver

> Tom, > > In my TB monitor kit, I used your Julian date routines, adapted to the 8051 > (no variable greater than 32 bits since my compiler does not support them > either) to apply the GPS offset correction. It was very helpful. > > Didier KO4BB Right. There are many ways to address the 1024

Re: [time-nuts] Setting correct date on Trimble Thunderbolt receiver

Hi Mark, > Heather keeps all times as a double precision Julian date. Using Heather's > code can > be a problem on Arduinos since their "double" precision numbers are actually > 32 bit > single precision, so you would need to do some more complicated math. Ah, more complicated math to solve

Re: [time-nuts] Setting correct date on Trimble Thunderbolt receiver

Don, The primary purpose of a Thunderbolt GPSDO is ultra-precise time (1PPS) and frequency (10 MHz), locked to each other, and to UTC. The good news is these two BNC outputs are unaffected by the date issue that you describe. The TBolt is designed to run fine on its own; you typically don't

Re: [time-nuts] Odetics Telecom CommSync - GPS Rollover Problem.

sage - From: "Rob Kimberley via time-nuts" <time-nuts@febo.com> To: "'Discussion of precise time and frequency measurement'" <time-nuts@febo.com> Sent: Friday, March 23, 2018 1:50 PM Subject: [time-nuts] Odetics Telecom CommSync - GPS Rollover Problem. > I wonder

Re: [time-nuts] WWVB Antenna revisited/Spectracom 8182

Donald, Your Skyscan radio clock, as well as all other consumer-grade WWVB clocks & watches, will continue to work. The new format was designed to be compatible with the old format so any receiver that gets time only from the AM subcode will continue to work. It's the commercial time &

[time-nuts] Stephen Hawking, an honorary time-nut

"Stephen Hawking dies aged 76" http://www.bbc.com/news/uk-43396008 "Obituary: Stephen Hawking" http://www.bbc.com/news/science-environment-1565 "Stephen Hawking, modern cosmology's brightest star, dies aged 76"

Re: [time-nuts] Recommendations for Mains Power Monitor / Logger

> In short, the GPS to UTC time correction polynomial got screwed up. Yes, that was an exciting time! For newcomers to the list, the bizarre GPS 13 microsecond jump was a hot topic on time-nuts back in 26-Jan-2016. The thread starts with an observation by Paul Boven:

Re: [time-nuts] Recommendations for Mains Power Monitor / Logger

> “Back in the day” we used WWV and the kitchen clock for that sort of thing…… Bob, Yes, not much has changed. I use multiple methods to measure 60 Hz in order to gain confidence in the results. Besides the picPET, I've used a commercial TrueTime TFDM (Time/Frequency Deviation Meter) and also

Re: [time-nuts] Recommendations for Mains Power Monitor / Logger

> I've done some Googling and have found any number of designs. Pat, 1) Safety. I usually use a low voltage step-down transformer. This gives isolation and safety. Anything from 3 VAC to 24 VAC is fine. 2) Trigger. There are dozens of schematics on the web for capturing the zero-crossing of a

Re: [time-nuts] Ultra low power RTC

> Since we don’t often *need* the smallest cell made *and* we’re probably > talking lifetime of the cell….. does 22 na vs 33 na matter? It gets even more amazing ... "A 1.5 nW, 32.768 kHz XTAL Oscillator Operational From a 0.3 V Supply"

Re: [time-nuts] ADEV data for mechanical clocks

> Does anybody have any ADEV data for mechanical clocks? (I didn't find any by > google, but there was a lot of noise so maybe I missed something.) Hal, It's often buried in out-of-print horological books or magazines / journals / articles that google may or may not index. I have some ADEV

Re: [time-nuts] Mechanical Precision Clocks

Hi Adrian, FYI -- Bill's also a long-time member of time-nuts. And he's also one of the reasons there is a time-nuts group. In the mid 90's I met Bill (and also Corby) through classified ads in Nuts & Volts magazine. Long story, but it was then that I learned it was "ok" to be interested in

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

d oscillator > There is indeed a 60Hz out picdiv from Tom Van Baak - > http://www.leapsecond.com/pic/picdiv.htm. It's not in that list but ask Tom. > > I've just used one (modified for 50Hz out) to drive a 1A H-bridge circuit > that supplies a 12V peak-peak square wave to an ol

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

Donald, Possible solutions to your 60 Hz mains problem: 1) If you don't want to open or hack the clock controller in any way consider using a "online" UPS. Typically the synthesized 60 Hz AC output is quartz controlled. 2) Make your own low-power 60 Hz AC/DC/AC power supply -- using a quartz,

Re: [time-nuts] Z3801A OCXO manual trimming

> Interesting point about the heater not working vs. the XTAL having drifted > too far. Any logs you made of EFC percent over the past few months or years will help verify the off-the-rail theory. Another thing to try -- turn-off the Z3801A for a couple of hours to let it cool. Disconnect the

Re: [time-nuts] FRK

Bert's M100 Rb teardown photos are now here: http://leapsecond.com/bert/m100.htm /tvb - Original Message - From: "ewkehren via time-nuts" To: "Discussion of precise time and frequency measurement" Sent: Sunday, February 25, 2018 6:05 AM

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

hings up at the levels involved in a good frequency standard. The old “when in doubt, throw it out” mantra may be a good one to keep in mind relative to a lot of add on features…. how much does a PIC-DIV pull compared to the 1 pps section of one of these old beasts (Cs or Rb)? Lots to think

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

attery alarm lamp, and voila, that noise went away. Makes sense when you think of the power variations associated with a blinking incandescent lamp. /tvb - Original Message - From: "Bob kb8tq" <kb...@n1k.org> To: "Tom Van Baak" <t...@leapsecond.com>; &quo

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

> BTW: Do you know the cause of the oscillations in the 5065 vs BVA plot? The ADEV wiggles aren't visible with normal tau 1 s measurements. But since the TimePod can go down to tau 1 ms, when I first measure a standard I like to run at that resolution so effects like this show up. Once that's

Re: [time-nuts] Selling Time and Frequency Equipment Or "just saying"

Corby, Thanks for your informative posting. I concur. Let me add a visual that echoes your comments. It's the same plot that I attached in the note about Ralph's lab. For those of you who can't view email attachments see [1]. The plot is ADEV of 4 typical lab frequency sources: - A 5071A in

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

This note is a follow-up to Ralph Devoe's ADEV posting earlier this month. It's a long story but last week I was in the Bay Area with a car full of batteries, BVA and cesium references, hp counters, and a TimePod. I was able to double check Ralph's Digilent-based ADEV device [1] and also to

Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

Let's keep this thread on topic and highly informative. Please treat time nuts as a technical mailing list, not social media. Thanks, /tvb Moderator, www.leapsecond.com/time-nuts.htm ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go

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

Hi Ralph, Nice test. Two comments. 1) Your 5065A is working really well; is it one of Corby's "super" ones? What sort of environmental controls did you have during the run, if any. How long had the 5065A been powered up before you ran the test? 2) Is there a reason you didn't or couldn't make

Re: [time-nuts] Anyone have experience with this antenna?

oops, sorry for the misfire. > I couldn't figure out how to get to the insides to take a peek > without damaging it. For $99 I would take the risk to damage it... Or find someone with x-ray gear and have a peak inside. Or take it with you on your next plane flight and grab a photo of the TSA

Re: [time-nuts] Anyone have experience with this antenna?

> testing. I couldn't figure out how to get to the insides to take a peek > without damaging it. My antenna testing abilities are pretty feeble. > Mostly, I will just compare it to the Leica and Trimble to see how many > satellites it sees and look at position wander of the uBlox. Is there any >

Re: [time-nuts] Rakon HSO-14

FYI: here's an old plot where I evaluated an Oscilloquartz 8607 BVA against a H-maser. It gets down to 8e-14 but is likely a bit better. On this plot, I suspect the short-term numbers were not the BVA oscillator or the TSC 5110A analyzer, but the H-maser. /tvb

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

> www.obsip.org/documents/Gardner_IEEE_Oceans_2016.pdf Also see the very nice presentation: "Challenges of precise timing underwater" http://www.ipgp.fr/~crawford/2017_EuroOBS_workshop/Resources/Gardner_OBS_Timing_ATG_20150427.pdf /tvb ___ time-nuts

Re: [time-nuts] minimalist sine to square

> Tom > What's the input signal amplitude? > What's the desired output signal (eg 5V CMOS, 3.3V CMOS etc)? > Bruce It's for a typical 5 or 10 MHz OCXO / Rb / Cs with sinewave output; say, 1 Vpp. The output should be 3.3 or 5 V depending on what the MCU needs. It doesn't have to have stunning

Re: [time-nuts] Looking for information regarding Trimble 33429-00 microcentered GPS antenna.

> What's in the antenna that makes North interesting? and/or how would a > receiver take advantage of it? Hal, The people that work at the mm level get very picky about details; antenna reception is not perfectly symmetrical or centered or equal at every frequency or angle. There is a

[time-nuts] minimalist sine to square

John's TADD-2-mini [1] uses the Wenzel sine-to-square converter. It performs very well but requires +10 V. I'm looking for a solution that works at 5 V (e.g., USB powered) and also uses fewer parts. Wenzel also mentions using a differential line receiver [2]. That would be an ideal single-chip

Re: [time-nuts] Tbolt 1pps

> Has any one done a 24 hour plot of the Tbolt 1pps. Hi Bert, There are plots of several GPSDO at http://leapsecond.com/pages/gpsdo/ including a Trimble Thunderbolt. It was one of the TAPR TBolt OEM surplus units that I measured in 2008. I uploaded the raw data for you here:

Re: [time-nuts] PBS, Tue evening, The Secret of Tuxedo Park

I can't stress enough how important Loomis was to the history of precise timekeeping in early radio, telephone, pendulum clock, quartz oscillator era. And for those of us who still have Loran-C receivers can thank him (Loomis Radio Navigation -> LRN -> Loran). So I highly recommend the 2003

Re: [time-nuts] hp 5245L counters with 10544 and 10811 OCXOs

ing the differences between > 10544 and 10811 connections. Feel free to post these on leapsecond.com, > as well. I've place Charles' PDF's at http://leapsecond.com/museum/10544/ Well worth the read. Thanks Charles. /tvb - Original Message - From: "Loney Duncan" &

Re: [time-nuts] hp 5245L counters with 10544 and 10811 OCXOs

Loney, You'll find the schematic for the 05245-60033 adapter board at the bottom of: http://leapsecond.com/museum/10544/ /tvb - Original Message - From: "Loney Duncan" To: Sent: Monday, January 08, 2018 8:08 PM Subject: [time-nuts] hp 5245L

Re: [time-nuts] HP 58503A question (EFC: Err)

you can read the live feed for this month at: www.febo.com/pipermail/time-nuts/2018-January/date.html If you want to read anything every written about the 58503A, on time-nuts search google using-- site:febo.com 58503A - Original Message - From: Mitch Van Ochten To: 'Tom Van Baak

Re: [time-nuts] Trimble Thunderbolt Power Cable Needed

> I have a dead T-Bolt that I want to trouble-shoot, but my only > > Power Cable is in use, so I need another Power Cable. > > Anyone have a spare that they are willing to part with ? > > Thanks, Dick, W1KSZ You can improvise using any 0.1 inch headers you have lying around. See "Alternative

Re: [time-nuts] Stable32 now available

I asked Bill for clarification and here's some of what he shared: > Tom: > > I’m glad that the word is getting out that Stable32 is now freely available. > The Version 1.62 that is available for download from the IEEE UFFC site is > identical to the last commercial Version 1.61 except for its

Re: [time-nuts] Stable32 now available

> From "Paul Alfille" : > Is the code be available, or just the compiled binary? I've asked Bill for clarification and will relay any information. > From "paul swed" > I suspect we need a Stable32 for dummies book. When I first started using

Re: [time-nuts] Recently acquired 53132A

Rick, The 53132A is a "12 digit/s" counter. Unless the frequency is really close to 10 MHz. Then it becomes a 11 digit/s counter. This is because it uses oversampling (IIRC, 200k samples/s) and it relies to some extent on statistics for its 12 digit resolution. This technique does not do as

Re: [time-nuts] Recently acquired 53132A

Pete, I don't recall that anyone complained much about the old 53132A, the counter that you have. The discussions we had about external reference a while ago were about new 53230A. There's nothing wrong with it, I mean, it's a very nice counter, but since it's a fancy, new design, high-end,

Re: [time-nuts] Oscilloquartz 8600-3 Disassembly pictures...

Ulf Kylenfall photos: http://leapsecond.com/museum/osa8600/ http://leapsecond.com/museum/osa8600/view.htm Ed Palmer text and photos: http://leapsecond.com/museum/osa8601/ http://leapsecond.com/museum/osa8601/view.htm ___ time-nuts mailing list --

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

I sent a note to Vlad off-list about the bug in the MCU code, but it's worth a reminder to the list as well since many of you are programmers and this arcane issue comes up every once in a while here and on the web. The way to compute time differences of free-running binary time counters is

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

Pat, > They drift a few seconds in the course of a few days, and wander back and > forth. Yes, it's normal for AC mains to drift around by a few seconds over a day but it usually stays roughly on-time over weeks and months. Here's an old example of monitoring mains time & frequency for 45

Re: [time-nuts] Pendulum clock suspension

List -- we don't normally do wrist watch or pendulum topics here on time-nuts. There are many publications [1] and forums [2] for that Iovane -- but, here's a quick answer: > This puzzled me since yesterday as I discovered how the suspension of > pendulum clocks is made, that is a springy

Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Mark, > In the standards definitions that include "at sea level", the question these > days is "which sea level?". Chris, > So does that mean e.g. NIST and BIPM need to measure the acceleration at > their respective locations to within parts in 10^17 or 10^18 in order to > compare their

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

Leo, About GPS and 1 ms... 1) Bob's version: Bob's succinct description is fine. There is often a 1 ms loop in GPS receiver firmware (you can see this in the spec for some timing receivers). It is not impossible that off-by-1 errors would occur at this level. 2) Book version: > Fundamentals

Re: [time-nuts] Input filter for data logger

> I'll need to experiment with this. I think the drawback cold be for the > signal with long pulse width (more than one second). > __|~~~ I'm not sure I understand. If you're building some kind of time interval counter or timestamp counter the duration is only

Re: [time-nuts] Input filter for data logger

Hi Vlad, > However, the logger measure it TWICE ! I think its because of that > signal form. Here is the output (in microseconds): Assuming the STM32 is set to trigger on the rising edge, a 2x output will occur if there is bounce from a falling edge. Normally this is not desirable, but there

Re: [time-nuts] Interpreting and Understanding Allen DeviationResults

Jerry: > For time interval as discussed below, the unaltered GPSDO output goes to A and > how do you create the GPSDO delay for B without a physical coax delay? You are correct. In Randal's hp 5335A frequency counter experiment he was splitting a single GPSDO 10 MHz output to both the REF input

Re: [time-nuts] Jefferts & Campbell recent papers

> These may be of interest, if the papers have not been circulated here before. > — Eric Links to the cesium and optical clock papers that Eric just mentioned are: 1) "Cesium Primary Frequency References" by Steven R. Jefferts, Thomas P. Heavner, Elizabeth A. Donley

Re: [time-nuts] Fwd: A talk on Atomic Clocks by Steve Jefferts NISTBoulder Wed 11/15

Eric -- Thanks much for that posting. List -- If you are interested in a summary of optical and lattice clocks, see: "A New Era for Atomic Clocks" https://phys.org/news/2014-02-era-atomic-clocks.html https://www.nist.gov/news-events/news/2014/02/new-era-atomic-clocks I also highly recommend

Re: [time-nuts] Favorite counters (current production)?

Magus: > Also, as being reported by the friends at Norwegian NMI, there is > something funky about. They got to borrow one from Ole Petter Rønningen. > It was there in the York EFTF 2016 poster session, and I even made a few > folks aware of it as "interesting". If I had more time, it would be

Re: [time-nuts] Favorite counters (current production)?

> Rank your preferences! I echo Magnus. In almost every photo of national timing labs you will see SR620's in use. The interface, specs, readability, and reliability are really good. Also SRS seems to support their products forever. For the curious, the full BOM and schematics are in the

Re: [time-nuts] ublox NEO-M8T improved by insulated chamber?

> How exactly do you measure offset of your GPS time output to absolute UTC > time? Conceptually it's no different from measuring your favorite resister or thermometer: you compare your DUT against a standard REF and the difference is your error, a process called calibration. So the same is

Re: [time-nuts] UltrAtomic clock.

> So, anyone notice what time their UltrAtomic clock did the dst change? > > Mine didn't change last night. Time has been right since it first set itself, > so, I'm suspecting it's getting signal. ( We're in northern Michigan, eastern > time zone.) Hi Dan, One of the advantages of the

Re: [time-nuts] HP 5335A Question

> The designers very well designed two near inifinite counter chains inside the > 5335A.. > I got my wisdom from the hp journal 9-1980. http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1980-09.pdf > They used a digital ASIC, called the MRC, multi-register counter, and it > allows counting > of

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

>> The DS3231 has an 8 bit register that will change its frequency in >> increments of about 0.1ppm. Thus you could discipline it to get its pps >> aligned with your reference. > > That sounds like you just designed the worst GPSDO ever. You could argue that the worst GPSDO ever is an operating

Re: [time-nuts] Distribution divider/amplifier for 10MHz GPSDO

List -- Don is having email trouble, but here's his posting: -- From: donaldbcol...@gmail.com Date: Tue, Oct 24, 2017 at 1:38 AM Subject: Distribution divider/amplifier for 10MHz GPSDO Hello group. I`m intending to distribute, via 50 Ohm coax, frequency reference signals to my test

Re: [time-nuts] Sulzer 2.5 For Sale

Hi Ruslan, > this standard appears to be ancient Yes. Sulzer oscillators are among of the best quartz frequency standards ever made. Good reading: "Brief History of the Development of Ultra-precise Oscillators for Ground and Space Applications"

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

> picPET -- Precision Event Timer http://www.leapsecond.com/pic/picpet.htm Thanks for the plug. Yes -- it does sub-microsecond relative time-stamping simply: one Schmitt-trigger TTL input pin and one RS232 output pin. But -- it's a $1 chip, not a black box. And the timestamps aren't UTC either.

Re: [time-nuts] current crop of GPS receivers for Rpi/Beaglebone forNTP server/etc

Jim, When I don't want to fuss with anything fancy I use these: https://www.adafruit.com/product/746 https://www.parallax.com/product/28511 https://www.parallax.com/product/28509 https://www.sparkfun.com/products/12751 /tvb - Original Message - From: "jimlux"

Re: [time-nuts] Question about SA.33 Rb clock

Hi Hui Zhang, > in the paper CSAC was described that it is based on CPT technology > My question is the SA.3x(or SA.2x) also used this method? Yes. Here's another good read; and it also includes photos of the inside of your SA.33:

Re: [time-nuts] NTP linked PC clock is slightly ahead of Lady Heather GPS time

>> These days the speaker is almost the last usable interface for this. > > ….. and the mic input is one of the few inputs left to feed “events” into. Yes, and by connecting the speaker to the mic and issuing a pulse through the speaker you can estimate the latency of the OS. It should act like

Re: [time-nuts] Novatel Dual frequency GNSS receivers on ebay

Christopher, Thanks for that additional information. Can you (or Gregory) also comment on the external frequency input / output and the 1PPS output of this receiver? A quick look at the om-2128.pdf and om-2129.pdf documents has words like "better than 250 ns accuracy" and "50 ns

Re: [time-nuts] Fw: Skytraq / GPS Almanac

Status -- all is back to normal with GPS as of this morning. At least for now, the folks that run GPS appear to have reversed the change made last week that triggered latent bugs in some receivers. A note from Said just now: > Hi Tom, > > Would you mind posting to Time nuts that this is a

[time-nuts] Fw: Skytraq / GPS Almanac

An interesting note from Said, below... I've sent a couple of queries out to GPS professionals. Feel free to comment if you have concrete information that would help. Also, if during the past week any of you were logging almanacs or continuously recording the 50 bps raw data from any GPS/SV,

Re: [time-nuts] Bad TBolt Crashing LH?

Everyone... We're going to take this issue off-list for a while. Mark (LH author) and others will work this out with Jerry by email and report back when all is known. Thanks, /tvb Moderator, http://leapsecond.com/time-nuts.htm - Original Message - From: "Jerry" To:

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

Please remember this is time nuts. This thread is straying far from timing and also becoming speculative instead of informative. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

Re: [time-nuts] Trimble Thunderbolt no longer determines the correct date

> The E911 installation, in the news, is just one of several. Others are > hospitals, > fire stations, etc. using different dispatch systems. Hey, at least important things like mobile phones, ISP's, Google, Amazon, FedEx and Starbucks aren't affected ;-) > In a wide-area simulcast-overlap

Re: [time-nuts] Trimble Thunderbolt no longer determines the correct date

Brad, Strictly speaking, there's no problem with GPS, or Trimble, or the Thunderbolt GPSDO: each did exactly as designed and documented. Anyone working with timing systems (from astronomy to calendars to watch making to operating systems) knows there are many subtle details. Just wait until

Re: [time-nuts] interesting HP divider and clock on ebay

> If the 115 has no motor (and I'm not questioning you, Bill) what moves the > "digital" numbers? It looks like a clock drive, and the 1968 HP catalog > makes reference to an "additional drum," which also sounds like a motor > drive. > > Jeremy The 115 does have a motor; the digital readout

Re: [time-nuts] interesting HP divider and clock on ebay

> Boy I have to say the front looks great. Good pixs to look at. > Price not exciting at all. But maybe someone has a spare kilo-buck. Paul, More info on the hp 115: http://hpmemoryproject.org/wb_pages/wall_b_page_01.htm /tvb ___ time-nuts mailing

Re: [time-nuts] SOPHOS discussion of GPS jamming and eLoran

> My apologies for the long link. Try this instead: https://nakedsecurity.sophos.com/2017/08/07/cyberattacks-on-gps-leave-ships-sailing-in-dangerous-waters Often when you see a long URL, or one full of strange numbers, it's encoded or encrypted personal tracking information. In this and many

Re: [time-nuts] Fwd: [hpsdr] SDR experiment for the solar eclipse

> We were originally going to put a 5071A-locked beacon on three ham > bands, but decided WWV and CHU would be better sources, and logistics > were turning into a problem: I'm going to be doing my wideband recording > from a cottage in northern Michigan. But I'm still a time-nut, so the >

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