Re: [time-nuts] clock and cannon at noon story
On Tue, Feb 4, 2014 at 6:22 PM, Michael Blazer mbla...@satx.rr.com wrote: Wouldn't the watchmaker notice that his clock is always a few seconds fast? If the cannon is a mile away, the watchmaker would be adjusting the clock so that 'noon' would sound around tea time after about 10 years. Now THAT is serious time-geek humor! -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ADEV computed, now what?
Bob wrote: here's the result for 1PPS vs 10MHz for my GPSDO, as measured by a 5334B clocked by the same 10MHz.I don't know how to read these, but 6,3,1,6,3,1 etc. doesn't look normal. The adev results you obtained look very much like the adev results reported by Lady Heather, very likely for the same reason -- you do not have any independent standard by which to measure. From what you say above, it appears that you measured the time interval between one edge of the PPS pulse and the next zero-cross of the GPSDO 10 MHz, using a 5334B clocked by the GPSDO 10 MHz. Is that correct? I take it the GPSDO is disciplined by the PPS? Bear in mind (i) that you are comparing one noisy source to another, and (ii) that the errors are correlated more and more strongly as tau increases beyond the point where the discipline loop begins controlling the 10 MHz oscillator. At small tau, the GPS PPS is very noisy (much noisier than the 10 MHz oscillator), and it gets better and better as you average for longer and longer periods until at tau above 10k it's reasonably decent. Your GPSDO should leave the oscillator more or less on its own at low tau (where the jitter in the oscillator is lower than the jitter in the PPS), and correct it beginning at some longer tau where the jitters are comparable (continuing to even longer tau where the jitter in the PPS is lower than the jitter in the oscillator). So, measuring as you appear to be doing, at low tau you are essentially measuring the improvement of the PPS with averaging -- 10x per decade -- using the essentially undisciplined 10 MHz oscillator as a standard. At some point, you would expect to reach a floor where you would essentially be measuring the residual jitter in the disciplined oscillator and the PPS. In fact, you can see this in your results starting around tau = 500, but your series does not go far enough to show the floor clearly. Bob suggested that you are measuring the trigger error of the 5334B, and that may be contributing to your results as well. With good measurement techniques, the outer bound of the 5334B trigger error should be less than 1nS, probably more like 200-300pS. Your actual error is probably significantly lower than this outer bound unless something is wrong with your setup. The trigger contribution to your computed adev should also fall 10x per decade with increasing tau. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ADEV computed, now what?
Hi Charles, I've had a night to digest what I'm seeing, and this is what I've come up with: There were only 2 updates to the DAC during the 24 hours tested. So, long term doesn't system drift dominate? That would include thermal drift and the stability of the OCXO. Also, there was a phase crossing for both of those updates. Short term there's the fact that this an Adafruit GPS Nav receiver (MTK-3339) with a spec of 10ns jitter. Looking at the GPS track, it is moving in a diamond shaped area about 41 ft from point to opposite point. Sometimes it's not a smooth movement, with a jerk of perhaps 6 feet. And there's the fact that the 1PPS has lots of ugly quantization errors, but I have no way of sensing them, much less correcting them. (The 5335B is not part of the loop. The phase error value is only an external measurement fed to my PC.) So, short term, it seems to be a measurement of the 1PPS from the MTK-3339, and long term a measurement of the drift of the Tekelec DOC-1903 OCXO, including the impact of the phase crossings that my code can't prevent. There is also the thermal drift in there somewhere, but it was very well behaved during this test run. OK, I've just reread your post, and it seems that I've just reworded it. Well, at least that means I'm beginning to understand what I have. I don't have any more accurate standards than this, so I don't see any way of improving my measurements. But, all in all, I'm satisfied that it's as accurate as I'll ever need. But, I'll probably keep fiddling with the code to see if I can eliminate that dependency on phase crossings to update the DAC. Bob From: Charles Steinmetz csteinm...@yandex.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, February 5, 2014 5:47 AM Subject: Re: [time-nuts] ADEV computed, now what? Bob wrote: here's the result for 1PPS vs 10MHz for my GPSDO, as measured by a 5334B clocked by the same 10MHz. I don't know how to read these, but 6,3,1,6,3,1 etc. doesn't look normal. The adev results you obtained look very much like the adev results reported by Lady Heather, very likely for the same reason -- you do not have any independent standard by which to measure. From what you say above, it appears that you measured the time interval between one edge of the PPS pulse and the next zero-cross of the GPSDO 10 MHz, using a 5334B clocked by the GPSDO 10 MHz. Is that correct? I take it the GPSDO is disciplined by the PPS? Bear in mind (i) that you are comparing one noisy source to another, and (ii) that the errors are correlated more and more strongly as tau increases beyond the point where the discipline loop begins controlling the 10 MHz oscillator. At small tau, the GPS PPS is very noisy (much noisier than the 10 MHz oscillator), and it gets better and better as you average for longer and longer periods until at tau above 10k it's reasonably decent. Your GPSDO should leave the oscillator more or less on its own at low tau (where the jitter in the oscillator is lower than the jitter in the PPS), and correct it beginning at some longer tau where the jitters are comparable (continuing to even longer tau where the jitter in the PPS is lower than the jitter in the oscillator). So, measuring as you appear to be doing, at low tau you are essentially measuring the improvement of the PPS with averaging -- 10x per decade -- using the essentially undisciplined 10 MHz oscillator as a standard. At some point, you would expect to reach a floor where you would essentially be measuring the residual jitter in the disciplined oscillator and the PPS. In fact, you can see this in your results starting around tau = 500, but your series does not go far enough to show the floor clearly. Bob suggested that you are measuring the trigger error of the 5334B, and that may be contributing to your results as well. With good measurement techniques, the outer bound of the 5334B trigger error should be less than 1nS, probably more like 200-300pS. Your actual error is probably significantly lower than this outer bound unless something is wrong with your setup. The trigger contribution to your computed adev should also fall 10x per decade with increasing tau. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] clock and cannon at noon story
In a somewhat contorted way, isn't this the same basic method that the national standards institutes use to keep their time ( and other standards) coordinated? No flames, please, I'm just kidding. Tom Holmes, N8ZM -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Tuesday, February 04, 2014 12:52 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] clock and cannon at noon story I suspect many of you have heard clock synchronization stories like this one (there are many variations): -- A chap was on holiday in Gibraltar. The tour guide said that before leaving Gib you had to see two things: The daily firing of the noon day gun on the rock and, down in the town square, the world's most accurate mechanical clock. So the bloke ambles up the rock in the morning, taking pictures of the apes and arriving at the gun just at noon. There are two men in ceremonial uniform stood ready, one next to the gun and one next to a telescope. The man with the telescope checks his watch, looks through the telescope and, at the right second, signals to the other guy who fires the cannon. The gaggle of spectators cheer and as one guy packs up the cannon the tourist ask the man what he was looking at through the telescope. 'Oh, from here you can see down into the town square and the world's most accurate clock, which is on the side of the local watchmaker's shop. When that says twelve we fire the cannon.' 'Oh, that's next on my list,' says the tourist, looking through the telescope, 'I'm off down there now.' After a pleasant stroll down to the town square the tourist finds himself stood looking up at the clock he had been seen through the telescope. The watchmaker sees him and comes out to say hello. 'I hear this is the most accurate clock in the world.' 'Yes,' says the watchmaker with some pride, 'It's not lost a second in the last one hundred years.' 'That's amazing,' says the tourist, 'how do you measure it?' 'Well', says the watchmaker, 'Every day at noon they fire a cannon and the clock is always spot on!' -- But I do have a serious question. If you have a favorite alternate version of this (from oral tradition, book, or web) please share it with me. It turns out there's some interesting time nuts math in some of them. Contact me off-list since this is a bit off-topic. You know my email: t...@leapsecond.com Thanks, /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] clock and cannon at noon story
Maybe he became hard of hearing and started observing the muzzle flash? -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
Hal, Interesting.. I'm assuming the green graph is actual voltage and the red graph is..? I've never done any mains monitoring/measuring and was wondering, what's your equipment setup? Thanks, Jimmy... N5SPE On Feb 4, 2014, at 8:43 PM, Hal Murray hmur...@megapathdsl.net wrote: This one caught my eye. Jan 20, 2014, Wed http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/2014-Jan-29-a-dip.png I think this is the biggest dip I've seen, down below 59.8 Hz. That's averaged over 10 seconds. Feb 02, 2014, Sun http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/2014-Feb-02-a-dip.png This one got below 59.9 Hz. I guess I should write some code to scan the archives. I wonder how many similar glitches I've missed. The last 50 days days: http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/Dec-2013.png Peak-peak offset is 15 seconds. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ECL Discussion: The On Semi MC100LVEL34 (/2/4/8 Prescaler/Divider)
Hello Mr. Westmoreland Yes we know that part and used in the past in many application in the previous incarnation from Motorola. Interestingly the older 5V parts were faster see the old Motorola datasheet, also for some reason the AZM parts were also faster, any goo explanation for that? Regards Alexander Pummer PCS Consultants 4349 Krause Street, Pleasanton CA 94588 (925) 461-9117 On 2/4/2014 11:48 PM, John C. Westmoreland, P.E. wrote: Hello, I was wondering how many of you have experience with this ECL part from On Semi: MC100LVEL34 ? The url is: http://www.onsemi.com/PowerSolutions/product.do?id=MC100LVEL34 I did search the archive - via Google - last discussion I saw was the new clock distribution part from Linear regarding ECL in this group. Specs on the MC100LVEL34 look nice; prop delay is good ( 1 ns), jitter ( 1 ps), and On Semi told me phase noise is expected to be -150dBc/Hz. ON also mentioned to me that they will start including phase noise figures with these parts soon (ECL). I was looking at the Peregine 3513 also - looks like a good part too; so do the ones from Hittite (GaAs). Peregrine does have a paper discussing Normalized Phase Noise in UltraCMOS Devices, but I don't see that speced for the PE3513. The Hittite HMC434/434E does spec Phase Noise at: Ultra Low SSB Phase Noise: -150 dBc/Hz Another ECL part that looks like it would make a nice RF switch is the: MC100EP58. Thanks and Regards, John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] housing multiple GPS timing receivers in the same box.
Le 5 févr. 2014 à 01:52, saidj...@aol.com a écrit : Michael, use a simple BNC T-splitter. Works perfectly for me as long as both GPS carry the same antenna voltage. No loss in signal quality evident from the C/No readings, and dirt-cheap. No need to over-complicate this. bye, Said Thanks Said, I'll take that route I think, though with SMA as it's a bit smaller. I'll just note here that I found that Mini-Circuits manufacture both through hole and smd parts covering the L1 band, so if I really needed the space I could try those. They are also much cheaper. Have a good one. In a message dated 2/4/2014 14:41:40 Pacific Standard Time, michael.c...@sfr.fr writes: ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] housing multiple GPS timing receivers in the same box.
As has been discussed before, a splitter intended for home satellite systems is a cheap solution as they have the bandwidth and the DC pass required. I have one between a couple of Thunderbolts. It powers the antenna and shows antenna OK on both. Using a splitter is better than just a T as it does lend some isolation between the receivers. David On 2/4/14 4:50 PM, mike cook wrote: Le 4 févr. 2014 à 22:35, Volker Esper a écrit : http://www.ebay.de/itm/HP-58516A-GPS-1-4-signal-Distribution-Amplifier-Splitter-N-type-/300997787447?pt=US_Ham_Radio_Receivershash=item4614ddbf37 I think I should have said that my box is only 25mm high. So any splitter will have to be less. A Mini Circuits splitter will just about do it , but I would prefer a smaller solution. Am 04.02.2014 14:08, schrieb mike cook: Hi, Till now I have been putting receivers in individual boxes. So to limit the growing number of boxes, I want to put two Resolution-T SMT receivers in one box, sharing power and antenna inputs. My question is How best can I share the antenna input, minimizing any interference between the receivers? . Will any interference matter? For example, I can easily connect three bits of shielded coax in a Y , but will probably get reflections from each receiver. As the cables will only be about 15cm long, would it matter? How about the DC antenna supply? The antenna DC will NOT be powering an antenna as it passes through a DC blocked splitter used to share an antenna between most of my receivers. I might be able squeeze a Mini-Circuits splitter in the box and DC-block both outputs but that may be overkill. What discrete circuitry might be a replacement? Will the Y do it? Someone must have already succeeded with this type of config. Thanks in advance for your input. Regards, Mike ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
Looking at PGE's sources of energy, 60% comes from easily controllable sources like gas, nuclear, and hydro. 40% comes from wind, solar, and other that are not so easily regulated. Steam generators can't me moved thermally as fast as winds drop or clouds develop. Then there is the load side, with who knows what equipment making large swings. It would be interesting to hear from other parts of the country, but cycle-watching hasn't caught the interest of this group yet. Bill Hawkins -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Tuesday, February 04, 2014 8:44 PM To: time-nuts@febo.com Cc: Hal Murray Subject: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley) This one caught my eye. Jan 20, 2014, Wed http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/2014-Jan-29-a-dip.png I think this is the biggest dip I've seen, down below 59.8 Hz. That's averaged over 10 seconds. Feb 02, 2014, Sun http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/2014-Feb-02-a-dip.png This one got below 59.9 Hz. I guess I should write some code to scan the archives. I wonder how many similar glitches I've missed. The last 50 days days: http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/Dec-2013.png Peak-peak offset is 15 seconds. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
On 2/5/2014 9:37 AM, Bill Hawkins wrote: Then there is the load side, with who knows what equipment making large swings. This reminds me of the time I visited the John Deere foundry in Waterloo, IA. They had an arc furnace with graphite rods the size of small utility poles. I remember the meters indicating 50,000 amps at 208 volts. Anyway, they told me that they had to call the power company and get permission before turning this thing on, or it might stall the generator. One time they forgot to call, and got fined $10,000 or something like that. Rick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
jimmydb...@gmail.com said: Interesting.. I'm assuming the green graph is actual voltage and the red graph is..? The green is the frequency as measured over the last 10 seconds. The red is the long term clock offset in cycles relative to what it would be if the frequency was exactly 60 Hz. It's the error you would see if you looked at a clock that was tracking the power line. The 0 point is arbitrary since I can't see the reference clock the power system is using. For those graphs, I used the start of the day/file as 0. I've never done any mains monitoring/measuring and was wondering, what's your equipment setup? It's simple. The hardware is an AC wall wart and a couple of resistors as a divider connected to a modem control pin. I forget which one. It's the one that ntpd expects to use with a PPS input. There was a discussion on that topic here a year or 3 ago. It's in the archives, but I couldn't find it with a quick look. The software is a simple python hack. It runs on Linux. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/pps.py Linux has a back door to the PPS info. Things like /sys/class/pps/pps0/assert give text like this: 1391619268.25084#1125070 The number left of the # is the time of the last PPS. The number to the right is the pulse count. The software above just waits 10 seconds, grabs another sample, and writes a line of text to a log file and switches to a new file every day. It's 1/2 megabyte per day. If you have FreeBSD or NetBSD rather than Linux, it shouldn't be too hard to use the same API as ntpd uses. I don't know how PPS works on Windows. Another approach would be to feed it into the audio input and scan for zero crossings. I captured the raw binary for a while when I was chasing some noise glitches. It's a lot of data. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TimeLab and the Adev plot
On 04/02/14 11:10, Azelio Boriani wrote: In the second sentence, I make the point that when you take two sample values, at various taus, you really do not average them but rather make their time stability contribution (trigger jitter and resolution) less important relative to the tau between them. This is by itself not an averaging effect. Agreed that it is not an averaging effect, then taking two samples at various tau is, for example, taking samples at 2 seconds instead of 1 second or using two samples for the actual tau under consideration? Well, if you want to analyse the tau=2 s ADEV case, you need to use 3 samples, with 2 s between them, which is exactly what the standard formulas use. If you have a systematic precision noise, that will fade with 1/tau and overshadow any actual DUT noise. If you have a 1 s tau sample series, you then only use every n sample for your n*tau0 analysis. Remember that you should at least do overlapping accumulation for better degrees of freedom and hence tighter confidence interval. The non-overlapping ADEV is only for historical reference. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Antenna - was receivers in the same box.
Guys, on this subject, we put together and qualified a convenient and complete (fairly) low-cost timing-compatible GPS antenna kit that includes all the mounting materials, 150 feet of cable, all the connectors, and down to the last screw, nut, and bolt everything one would need to mount the antenna. Only standard tools are required for the installation. Compatible to any L1 GPS receiver, works from 2.5V to 5V. We get up to 52dB C/No with 150 feet of cable on our uBlox GPS receivers with this antenna, and the antenna cable length can be easily extended with F-connectors on both sides. This was done because so many people had problems getting all the parts to put an antenna together and called us for pointers to antenna kits (which we could not find), and we went out and bought all the different pieces needed to do so and put these together as a kit. Check out the _www.jackson-labs.com_ (http://www.jackson-labs.com) website if interested. 10% Time-Nuts discount (one unit per person) - $241.20 per kit w/o the lightning arrestor. A bit more pricey when the antenna lightning surge protector is included which is mandatory for any outdoor installation. I know this is more than what you would pay for a used antenna on Ebay, but we are not really making any money on this, we are pretty much selling it as a convenience to our customers. Please contact us off-this-list if interested. bye, Said In a message dated 2/5/2014 09:46:27 Pacific Standard Time, n1...@dartmouth.edu writes: As has been discussed before, a splitter intended for home satellite systems is a cheap solution as they have the bandwidth and the DC pass required. I have one between a couple of Thunderbolts. It powers the antenna and shows antenna OK on both. Using a splitter is better than just a T as it does lend some isolation between the receivers. David On 2/4/14 4:50 PM, mike cook wrote: Le 4 févr. 2014 à 22:35, Volker Esper a écrit : http://www.ebay.de/itm/HP-58516A-GPS-1-4-signal-Distribution-Amplifier-Splitter-N-type-/300997787447?pt=US_Ham_Radio_Receivershash=item4614ddbf37 I think I should have said that my box is only 25mm high. So any splitter will have to be less. A Mini Circuits splitter will just about do it , but I would prefer a smaller solution. Am 04.02.2014 14:08, schrieb mike cook: Hi, Till now I have been putting receivers in individual boxes. So to limit the growing number of boxes, I want to put two Resolution-T SMT receivers in one box, sharing power and antenna inputs. My question is How best can I share the antenna input, minimizing any interference between the receivers? . Will any interference matter? For example, I can easily connect three bits of shielded coax in a Y , but will probably get reflections from each receiver. As the cables will only be about 15cm long, would it matter? How about the DC antenna supply? The antenna DC will NOT be powering an antenna as it passes through a DC blocked splitter used to share an antenna between most of my receivers. I might be able squeeze a Mini-Circuits splitter in the box and DC-block both outputs but that may be overkill. What discrete circuitry might be a replacement? Will the Y do it? Someone must have already succeeded with this type of config. Thanks in advance for your input. Regards, Mike ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
For your setup measuring mains there will be a large phase difference across the transformer. This is due to very many physical properties of the materials, the largest being the magnetic succeptability of the core. Now, this does show a slight temperature dependance. So how do you know that you are not getting a slow variation in the phase showing up as a frequency shift, since you are measuring such tiny variations. I know that the transformer is probably in thermal equilibrium with it's surroundings, so is at a steady temperature, but this problem (of getting an accurate idea of mains frequency phase) has exercised me over the years. I currently use an opto and voltage reference to get mains frequency, phase and voltage (computed by lookup table from pulse width) which I found was more stable than a transformer. And cheaper as well, since this is for a commercial product. I'm just surprised that you get such results with a cheap transformer. Just remembered, we got a tiny change in phase shift across a transformer due to its orientation, we could turn it 90 Deg and get a tiny change (less than a milliradian), we never got to the bottom of it, maybe the Earth's magnetic field? Tom Harris celephi...@gmail.com On 6 February 2014 04:39, Hal Murray hmur...@megapathdsl.net wrote: jimmydb...@gmail.com said: Interesting.. I'm assuming the green graph is actual voltage and the red graph is..? The green is the frequency as measured over the last 10 seconds. The red is the long term clock offset in cycles relative to what it would be if the frequency was exactly 60 Hz. It's the error you would see if you looked at a clock that was tracking the power line. The 0 point is arbitrary since I can't see the reference clock the power system is using. For those graphs, I used the start of the day/file as 0. I've never done any mains monitoring/measuring and was wondering, what's your equipment setup? It's simple. The hardware is an AC wall wart and a couple of resistors as a divider connected to a modem control pin. I forget which one. It's the one that ntpd expects to use with a PPS input. There was a discussion on that topic here a year or 3 ago. It's in the archives, but I couldn't find it with a quick look. The software is a simple python hack. It runs on Linux. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/pps.py Linux has a back door to the PPS info. Things like /sys/class/pps/pps0/assert give text like this: 1391619268.25084#1125070 The number left of the # is the time of the last PPS. The number to the right is the pulse count. The software above just waits 10 seconds, grabs another sample, and writes a line of text to a log file and switches to a new file every day. It's 1/2 megabyte per day. If you have FreeBSD or NetBSD rather than Linux, it shouldn't be too hard to use the same API as ntpd uses. I don't know how PPS works on Windows. Another approach would be to feed it into the audio input and scan for zero crossings. I captured the raw binary for a while when I was chasing some noise glitches. It's a lot of data. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
Hal, Thanks for the info. I think I'm going to give it a go. At any rate it's a good excuse to buy another Raspberry pi :) Thanks for the python source too. Looks useful. Jimmy... N5SPE On Feb 5, 2014, at 11:39 AM, Hal Murray hmur...@megapathdsl.net wrote: jimmydb...@gmail.com said: Interesting.. I'm assuming the green graph is actual voltage and the red graph is..? The green is the frequency as measured over the last 10 seconds. The red is the long term clock offset in cycles relative to what it would be if the frequency was exactly 60 Hz. It's the error you would see if you looked at a clock that was tracking the power line. The 0 point is arbitrary since I can't see the reference clock the power system is using. For those graphs, I used the start of the day/file as 0. I've never done any mains monitoring/measuring and was wondering, what's your equipment setup? It's simple. The hardware is an AC wall wart and a couple of resistors as a divider connected to a modem control pin. I forget which one. It's the one that ntpd expects to use with a PPS input. There was a discussion on that topic here a year or 3 ago. It's in the archives, but I couldn't find it with a quick look. The software is a simple python hack. It runs on Linux. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/pps.py Linux has a back door to the PPS info. Things like /sys/class/pps/pps0/assert give text like this: 1391619268.25084#1125070 The number left of the # is the time of the last PPS. The number to the right is the pulse count. The software above just waits 10 seconds, grabs another sample, and writes a line of text to a log file and switches to a new file every day. It's 1/2 megabyte per day. If you have FreeBSD or NetBSD rather than Linux, it shouldn't be too hard to use the same API as ntpd uses. I don't know how PPS works on Windows. Another approach would be to feed it into the audio input and scan for zero crossings. I captured the raw binary for a while when I was chasing some noise glitches. It's a lot of data. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
Whoa! That's hilarious... and sort of scary all at the same time :) Thanks for the story, Rick. Jimmy... N5SPE On Feb 5, 2014, at 12:06 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 2/5/2014 9:37 AM, Bill Hawkins wrote: Then there is the load side, with who knows what equipment making large swings. This reminds me of the time I visited the John Deere foundry in Waterloo, IA. They had an arc furnace with graphite rods the size of small utility poles. I remember the meters indicating 50,000 amps at 208 volts. Anyway, they told me that they had to call the power company and get permission before turning this thing on, or it might stall the generator. One time they forgot to call, and got fined $10,000 or something like that. Rick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
Tom, You sound like a guy who just might have experimented with different core materials for your transformer? Any suggestions for rolling your own? I'd love to hear more about your pulse monitoring/measuring setup if it's something you can share. Thanks, Jimmy... N5SPE On Feb 5, 2014, at 4:40 PM, Tom Harris celephi...@gmail.com wrote: For your setup measuring mains there will be a large phase difference across the transformer. This is due to very many physical properties of the materials, the largest being the magnetic succeptability of the core. Now, this does show a slight temperature dependance. So how do you know that you are not getting a slow variation in the phase showing up as a frequency shift, since you are measuring such tiny variations. I know that the transformer is probably in thermal equilibrium with it's surroundings, so is at a steady temperature, but this problem (of getting an accurate idea of mains frequency phase) has exercised me over the years. I currently use an opto and voltage reference to get mains frequency, phase and voltage (computed by lookup table from pulse width) which I found was more stable than a transformer. And cheaper as well, since this is for a commercial product. I'm just surprised that you get such results with a cheap transformer. Just remembered, we got a tiny change in phase shift across a transformer due to its orientation, we could turn it 90 Deg and get a tiny change (less than a milliradian), we never got to the bottom of it, maybe the Earth's magnetic field? Tom Harris celephi...@gmail.com On 6 February 2014 04:39, Hal Murray hmur...@megapathdsl.net wrote: jimmydb...@gmail.com said: Interesting.. I'm assuming the green graph is actual voltage and the red graph is..? The green is the frequency as measured over the last 10 seconds. The red is the long term clock offset in cycles relative to what it would be if the frequency was exactly 60 Hz. It's the error you would see if you looked at a clock that was tracking the power line. The 0 point is arbitrary since I can't see the reference clock the power system is using. For those graphs, I used the start of the day/file as 0. I've never done any mains monitoring/measuring and was wondering, what's your equipment setup? It's simple. The hardware is an AC wall wart and a couple of resistors as a divider connected to a modem control pin. I forget which one. It's the one that ntpd expects to use with a PPS input. There was a discussion on that topic here a year or 3 ago. It's in the archives, but I couldn't find it with a quick look. The software is a simple python hack. It runs on Linux. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/pps.py Linux has a back door to the PPS info. Things like /sys/class/pps/pps0/assert give text like this: 1391619268.25084#1125070 The number left of the # is the time of the last PPS. The number to the right is the pulse count. The software above just waits 10 seconds, grabs another sample, and writes a line of text to a log file and switches to a new file every day. It's 1/2 megabyte per day. If you have FreeBSD or NetBSD rather than Linux, it shouldn't be too hard to use the same API as ntpd uses. I don't know how PPS works on Windows. Another approach would be to feed it into the audio input and scan for zero crossings. I captured the raw binary for a while when I was chasing some noise glitches. It's a lot of data. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 Hz power glitch, US West coast (Silicon Valley)
Hal is graphing seconds of offset and seeing 5 seconds worth of shift in one day. Worrying about phase shift across the transformer changing with temperature, is like rearranging deck chairs on the titanic :-) Tim N3QE On Wed, Feb 5, 2014 at 5:40 PM, Tom Harris celephi...@gmail.com wrote: For your setup measuring mains there will be a large phase difference across the transformer. This is due to very many physical properties of the materials, the largest being the magnetic succeptability of the core. Now, this does show a slight temperature dependance. So how do you know that you are not getting a slow variation in the phase showing up as a frequency shift, since you are measuring such tiny variations. I know that the transformer is probably in thermal equilibrium with it's surroundings, so is at a steady temperature, but this problem (of getting an accurate idea of mains frequency phase) has exercised me over the years. I currently use an opto and voltage reference to get mains frequency, phase and voltage (computed by lookup table from pulse width) which I found was more stable than a transformer. And cheaper as well, since this is for a commercial product. I'm just surprised that you get such results with a cheap transformer. Just remembered, we got a tiny change in phase shift across a transformer due to its orientation, we could turn it 90 Deg and get a tiny change (less than a milliradian), we never got to the bottom of it, maybe the Earth's magnetic field? Tom Harris celephi...@gmail.com On 6 February 2014 04:39, Hal Murray hmur...@megapathdsl.net wrote: jimmydb...@gmail.com said: Interesting.. I'm assuming the green graph is actual voltage and the red graph is..? The green is the frequency as measured over the last 10 seconds. The red is the long term clock offset in cycles relative to what it would be if the frequency was exactly 60 Hz. It's the error you would see if you looked at a clock that was tracking the power line. The 0 point is arbitrary since I can't see the reference clock the power system is using. For those graphs, I used the start of the day/file as 0. I've never done any mains monitoring/measuring and was wondering, what's your equipment setup? It's simple. The hardware is an AC wall wart and a couple of resistors as a divider connected to a modem control pin. I forget which one. It's the one that ntpd expects to use with a PPS input. There was a discussion on that topic here a year or 3 ago. It's in the archives, but I couldn't find it with a quick look. The software is a simple python hack. It runs on Linux. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/pps.py Linux has a back door to the PPS info. Things like /sys/class/pps/pps0/assert give text like this: 1391619268.25084#1125070 The number left of the # is the time of the last PPS. The number to the right is the pulse count. The software above just waits 10 seconds, grabs another sample, and writes a line of text to a log file and switches to a new file every day. It's 1/2 megabyte per day. If you have FreeBSD or NetBSD rather than Linux, it shouldn't be too hard to use the same API as ntpd uses. I don't know how PPS works on Windows. Another approach would be to feed it into the audio input and scan for zero crossings. I captured the raw binary for a while when I was chasing some noise glitches. It's a lot of data. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] MC100LVEL34
I was wondering how many of you have experience with this ECL part from On Semi: MC100LVEL34 ? John, I use this part quite a bit. Great for 100 MHz distribution in out cold atom systems. Also used it with good luck in dividing the output of a 320 MHz VCSO in a cavity lock servo. You can get about 5 dBm out of PECL after the transformer and LPF!! Cheers, John Pease ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] MC100LVEL34
Hello John, Did you happen to do any phase noise measurements? Thanks, John W. On Wed, Feb 5, 2014 at 10:07 PM, John Pease john_pease...@yahoo.com wrote: I was wondering how many of you have experience with this ECL part from On Semi: MC100LVEL34 ? John, I use this part quite a bit. Great for 100 MHz distribution in out cold atom systems. Also used it with good luck in dividing the output of a 320 MHz VCSO in a cavity lock servo. You can get about 5 dBm out of PECL after the transformer and LPF!! Cheers, John Pease ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
