[time-nuts] 60 Hz frequency and phase measurement
In order to add Truetime XL-DC (and XLi support) to Lady Heather, I bought an XL-DC that happened to have the FTM-III module in it. This module is designed to measure power line frequency for generating stations, etc, It works well, but the minimum integration time is one second. You can specify the integration interval (100,000 seconds (?) max. It also does not measure voltage.Heather can calculate xDEVs and MTIE from the data. I had a nice run captured but lost it. I'll do another run and post it when I am able to do another run. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
On 7/3/19 3:20 PM, Jeremy Nichols wrote: The station at Santa Rosa, California (#853 in the Western Interconnection) is mine. Have had their receiver for several years. Only downside is that i can't record the data directly from the supplied receiver. Jeremy but what can you tell us about the receiver - I assume it's line connected. How does it get time hacks? GPS? Maybe it takes a feed from the de-rigueur Hydrogen maser, Cs fountain, or cryogenic sapphire oscillator that time-nuts just happen to have around? ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
The station at Santa Rosa, California (#853 in the Western Interconnection) is mine. Have had their receiver for several years. Only downside is that i can't record the data directly from the supplied receiver. Jeremy On Wed, Jul 3, 2019 at 12:01 PM Paul Theodoropoulos via time-nuts < time-nuts@lists.febo.com> wrote: > This stuff is fascinating to a time-nut-level:Novice such as myself. > While falling down the rabbit-hole searching on all the various bits of > the info below, I ran across this - not sure if you're aware of it, or > if it's old news, but it seems at least peripherally interesting: > > http://fnetpublic.utk.edu > > > On 7/3/19 08:56, Tom Van Baak wrote: > > Bob, > > > > Several of us do long-term measurement of mains frequency. We tend to > > time-stamp cycles and then compute period or frequency, rather than > > measuring frequency or period directly. Traditional counters in gated > > frequency or time interval mode have dead time and this will skew > > results. > > > > In my case I just run a 5 VAC wall-wart through a 10k resistor > > directly to the input pin of a PIC. No scaling, no filtering, no opto, > > no ZCD, no nothing. If I measure every cycle I get 155 million samples > > per month. If I extract one cycle each second (decimate by 60) it's > > only 2.5 million samples a month. Many months there is not a single > > glitch in the data in spite of all the FUD about power line noise. > > Once in a while a month contains an extra or missing sample but the > > beauty of timestamp data is that this can be detected and repaired as > > part of data processing with no loss of phase. > > > > Here's a page where Kevin (in New Mexico) and I (in Seattle) both used > > picPET's to measure mains for a few days and then we compared the > > results. Although thousands of miles apart, we're both on the same > > grid so the agreement was astonishing. It was milliseconds in time and > > ADEV down to e-8 over a day: > > > > http://leapsecond.com/pages/mains-cv/ > > > > See also: http://leapsecond.com/pic/mains-adev-mdev-gnuplot-g4.png > > > > /tvb > > > > > > On 7/2/2019 10:09 PM, Bob Albert via time-nuts wrote: > >> I have tried to measure the power line frequency with spotty > >> success. My best results came from a period measurement, as many > >> periods as the counter can accumulate. Due to noise, one is never > >> sure at quite what point the source is measured. Perhaps a brick > >> wall filter would clean it up for a more reliable measurement. > >> Of course, at 60 Hz the period is 16-2/3 milliseconds. So the > >> counter should properly show a 1 followed by a row of 6s, with the > >> last digit bouncing between 6 and 7 most of the time. > >> If there is a filter used, it will not only remove noise but also > >> short term variations. But generatlly speaking you don't want to > >> measure those, unless you are trying to evaluate a rotary generator. > >> Getting this reading can be a challenge. > >> On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux > >> wrote: > >> On 7/2/19 4:09 PM, Dana Whitlow wrote: > >>> I've always noted that casual attempts to pick up 60 Hz with small > >>> antennas > >>> etc see more harmonics and other trash than actual line frequency. > >>> But if > >>> you're in an office environment, why not plug something in? It's > >>> quite easy > >>> to build a simple passive diode clipper/filter that will plug into a > >>> wall > >>> outlet and > >>> which will provide a sort of soft (but clean) squarewave at a > >>> voltage level > >>> convenient for lab instruments and with good protection against big > >>> spikes > >>> and > >>> other trash riding on the line. > >> > >> Safety approvals are one obstacle (of course one could use a AC wall > >> wart). > >> > >> Actually, it's because someone asked me about a science experiment where > >> you'd place them in a neighborhood outdoors. > >> > >> > >> > >> ___ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > >>___ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > -- > Paul Theodoropoulos > www.anastrophe.com > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___
Re: [time-nuts] TimeLab phase difference (slope sec/sec)
Hi If the data is GPS referenced it is not at all uncommon to see a roughly 24 hour pattern in the data. Ionospheric changes are one significant contributor. The further down into the mud you get, the more other things pop up (multipath repeating with the same constalation ….) Bob > On Jul 3, 2019, at 1:44 PM, Chris Burford wrote: > > Hello David, > > It could quite possibly be tempco induced. I have this on my schedule of > future events for additional analysis. > > Thanks, > > Chris > >> >> Chris, >> >> Just looking at the graph reminds me of a daily variation - perhaps due to >> temperature. Is that likely? Would a two-day graph be worth doing in this >> particular case? >> >> Cheers, >> David > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
This stuff is fascinating to a time-nut-level:Novice such as myself. While falling down the rabbit-hole searching on all the various bits of the info below, I ran across this - not sure if you're aware of it, or if it's old news, but it seems at least peripherally interesting: http://fnetpublic.utk.edu On 7/3/19 08:56, Tom Van Baak wrote: Bob, Several of us do long-term measurement of mains frequency. We tend to time-stamp cycles and then compute period or frequency, rather than measuring frequency or period directly. Traditional counters in gated frequency or time interval mode have dead time and this will skew results. In my case I just run a 5 VAC wall-wart through a 10k resistor directly to the input pin of a PIC. No scaling, no filtering, no opto, no ZCD, no nothing. If I measure every cycle I get 155 million samples per month. If I extract one cycle each second (decimate by 60) it's only 2.5 million samples a month. Many months there is not a single glitch in the data in spite of all the FUD about power line noise. Once in a while a month contains an extra or missing sample but the beauty of timestamp data is that this can be detected and repaired as part of data processing with no loss of phase. Here's a page where Kevin (in New Mexico) and I (in Seattle) both used picPET's to measure mains for a few days and then we compared the results. Although thousands of miles apart, we're both on the same grid so the agreement was astonishing. It was milliseconds in time and ADEV down to e-8 over a day: http://leapsecond.com/pages/mains-cv/ See also: http://leapsecond.com/pic/mains-adev-mdev-gnuplot-g4.png /tvb On 7/2/2019 10:09 PM, Bob Albert via time-nuts wrote: I have tried to measure the power line frequency with spotty success. My best results came from a period measurement, as many periods as the counter can accumulate. Due to noise, one is never sure at quite what point the source is measured. Perhaps a brick wall filter would clean it up for a more reliable measurement. Of course, at 60 Hz the period is 16-2/3 milliseconds. So the counter should properly show a 1 followed by a row of 6s, with the last digit bouncing between 6 and 7 most of the time. If there is a filter used, it will not only remove noise but also short term variations. But generatlly speaking you don't want to measure those, unless you are trying to evaluate a rotary generator. Getting this reading can be a challenge. On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux wrote: On 7/2/19 4:09 PM, Dana Whitlow wrote: I've always noted that casual attempts to pick up 60 Hz with small antennas etc see more harmonics and other trash than actual line frequency. But if you're in an office environment, why not plug something in? It's quite easy to build a simple passive diode clipper/filter that will plug into a wall outlet and which will provide a sort of soft (but clean) squarewave at a voltage level convenient for lab instruments and with good protection against big spikes and other trash riding on the line. Safety approvals are one obstacle (of course one could use a AC wall wart). Actually, it's because someone asked me about a science experiment where you'd place them in a neighborhood outdoors. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. -- Paul Theodoropoulos www.anastrophe.com ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] TimeLab phase difference (slope sec/sec)
Hello David, It could quite possibly be tempco induced. I have this on my schedule of future events for additional analysis. Thanks, Chris Chris, Just looking at the graph reminds me of a daily variation - perhaps due to temperature. Is that likely? Would a two-day graph be worth doing in this particular case? Cheers, David ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
Wow Tom that is great work! I won't pretend to understand what you did and how you did it or, even, what the various graphs represent. But one thing I get out of it is the amazing correlation of measurements made across such a distance. And the equally amazing accuracy, stability, and precision of the mains frequency. It inspires me to push aside my current project and see how consistent my own results can be. I would revert to my original method of period measurement, perhaps modified by the addition of a simple filter. Now that my counter is solidly on the money due to the rubidium oscillator, I can trust the readings for as many digits as I can count. My little motor driven electric clock has never needed resetting other than the switch to and from daylight time. But of course that's a rather gross measurement. I wonder what method the power companies use to control frequency and who decides what is the correct signal. Presumably there is an ivory tower somewhere with a cloistered team of bearded scientists who hold magnifying glasses to oscilloscope screens to decide when to throw another lump of coal into the furnace. Bob On Wednesday, July 3, 2019, 09:01:16 AM PDT, Tom Van Baak wrote: Bob, Several of us do long-term measurement of mains frequency. We tend to time-stamp cycles and then compute period or frequency, rather than measuring frequency or period directly. Traditional counters in gated frequency or time interval mode have dead time and this will skew results. In my case I just run a 5 VAC wall-wart through a 10k resistor directly to the input pin of a PIC. No scaling, no filtering, no opto, no ZCD, no nothing. If I measure every cycle I get 155 million samples per month. If I extract one cycle each second (decimate by 60) it's only 2.5 million samples a month. Many months there is not a single glitch in the data in spite of all the FUD about power line noise. Once in a while a month contains an extra or missing sample but the beauty of timestamp data is that this can be detected and repaired as part of data processing with no loss of phase. Here's a page where Kevin (in New Mexico) and I (in Seattle) both used picPET's to measure mains for a few days and then we compared the results. Although thousands of miles apart, we're both on the same grid so the agreement was astonishing. It was milliseconds in time and ADEV down to e-8 over a day: http://leapsecond.com/pages/mains-cv/ See also: http://leapsecond.com/pic/mains-adev-mdev-gnuplot-g4.png /tvb On 7/2/2019 10:09 PM, Bob Albert via time-nuts wrote: > I have tried to measure the power line frequency with spotty success. My >best results came from a period measurement, as many periods as the counter >can accumulate. Due to noise, one is never sure at quite what point the >source is measured. Perhaps a brick wall filter would clean it up for a more >reliable measurement. > Of course, at 60 Hz the period is 16-2/3 milliseconds. So the counter should > properly show a 1 followed by a row of 6s, with the last digit bouncing > between 6 and 7 most of the time. > If there is a filter used, it will not only remove noise but also short term > variations. But generatlly speaking you don't want to measure those, unless > you are trying to evaluate a rotary generator. > Getting this reading can be a challenge. > On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux >wrote: > > On 7/2/19 4:09 PM, Dana Whitlow wrote: >> I've always noted that casual attempts to pick up 60 Hz with small antennas >> etc see more harmonics and other trash than actual line frequency. But if >> you're in an office environment, why not plug something in? It's quite easy >> to build a simple passive diode clipper/filter that will plug into a wall >> outlet and >> which will provide a sort of soft (but clean) squarewave at a voltage level >> convenient for lab instruments and with good protection against big spikes >> and >> other trash riding on the line. > > Safety approvals are one obstacle (of course one could use a AC wall wart). > > Actually, it's because someone asked me about a science experiment where > you'd place them in a neighborhood outdoors. > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts
Re: [time-nuts] TimeLab phase difference (slope sec/sec)
Hi Dana, My PRS10 is the DUT that has its 1PPS(Out) wired into the TICC on ChA. The reference is my GPSDO which has a 8663-XS DOCXO and has its 1PPS(Out) wired into the TICC on ChB. The 10 MHz clock signal for the TICC comes from my GPSDO also, which as I understand, need not be quite so precise when measuring in time interval mode. Chris On 07/03/19 04:01:38, Dana Whitlow wrote: Chris, Ok, one source is a PRS-10. Is it the DUT or the reference? And if it's the DUT, what is the reference source? Dana On Tue, Jul 2, 2019 at 8:00 PM Chris Burford wrote: Hi Bob, I'm seeing 4.22E-12 as the slope value in the upper right of the TimeLab phase difference plot. Is that telling me that my DUT is within +4.22ps / sec from my reference 1PPS for the 24 hour measurement duration? I have attached a screen capture that will hopefully make its way through for viewing. Thanks, Chris On 07/02/19 11:50:10, Bob kb8tq wrote: Hi The difference in seconds between the start phase and the end phase divided by the number of seconds duration gives you the parts in whatever of the error. If you see 1us ( = 1x10^-6 seconds) of change in a second, you are off by 1 ppm (or 1x10^-6). If you see 1 us of change in 1,000 seconds you are off by 1 ppb (or 1x10^-9). At a bit over 10 days (1,000,000 seconds) your 1 us change is 1 ppt (or 1x10^-12). Bob On Jul 2, 2019, at 10:17 AM, Chris Burford wrote: Is the slope value for the phase difference shown in TimeLab an average of the overall data sample duration? The reason I ask is that my service manual for my RFS says: /"//A faster way to make the comparison between the reference frequency and the DUT is to use the time interval measurement mode of the counters. In this case, the time intervals between the 10MHz zero crossings of the reference frequency and the DUT are measured and averaged. If this time interval changes by less than 10ps per second, then the DUT is within 1 part in //10^11 of the frequency reference."/ I'm just curious if the phase difference slope value can be plugged in to this equation. Regards, Chris ___ time-nuts mailing list --time-nuts@lists.febo.com To unsubscribe, go tohttp:// lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list --time-nuts@lists.febo.com To unsubscribe, go tohttp:// lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list --time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list --time-nuts@lists.febo.com To unsubscribe, go tohttp://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
On 7/3/19 8:56 AM, Tom Van Baak wrote: Bob, Several of us do long-term measurement of mains frequency. We tend to time-stamp cycles and then compute period or frequency, rather than measuring frequency or period directly. Traditional counters in gated frequency or time interval mode have dead time and this will skew results. In my case I just run a 5 VAC wall-wart through a 10k resistor directly to the input pin of a PIC. No scaling, no filtering, no opto, no ZCD, no nothing. If I measure every cycle I get 155 million samples per month. If I extract one cycle each second (decimate by 60) it's only 2.5 million samples a month. Many months there is not a single glitch in the data in spite of all the FUD about power line noise. Once in a while a month contains an extra or missing sample but the beauty of timestamp data is that this can be detected and repaired as part of data processing with no loss of phase. Here's a page where Kevin (in New Mexico) and I (in Seattle) both used picPET's to measure mains for a few days and then we compared the results. Although thousands of miles apart, we're both on the same grid so the agreement was astonishing. It was milliseconds in time and ADEV down to e-8 over a day: http://leapsecond.com/pages/mains-cv/ See also: http://leapsecond.com/pic/mains-adev-mdev-gnuplot-g4.png /tvb yes indeed http://fnetpublic.utk.edu/anglecontour.html shows a pretty constant phase shift of tens of degrees. (except Texas, because, after all, they're Texas) ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
On 7/2/19 11:47 PM, Hal Murray wrote: jim...@earthlink.net said: Actually, it's because someone asked me about a science experiment where you'd place them in a neighborhood outdoors. Sounds like another science experiment: build an antenna to pick up 60 Hz. You could start with the typical ferrite, coil, and cap. Just adjust the cap to your new target frequency. Simple to try. I ran through some quick calculations on that - unlike for AM band, you need a fairly good sized capacitor. I think it's doable. A typical loopstick for AM is around 0.5 to 1 mH, so you'd need about 7000 microfarads to resonate it at 60Hz. So, a LOT more turns on that inductor. And then you have to start worrying about phase shift - it's going to be a fairly high Q resonant circuit, with the phase varying most rapidly around resonance. So a resonant antenna probably isn't the way to go.. The whole goal is to look for phase shifts after all. That's why I was thinking about magnetic field sensors.. The little electronic compass sensors sample at 100-300 Hz and have sensitivities comparable to the Earth's field (i.e. something like 2 Gauss, 200 microTesla, full scale). I don't know that they're sensitive enough - I recall that typical line frequency fields are in the "single digit milliGauss" range. If I convert that the E field, I get "single digit Volts/meter" - which is consistent with my tens of mV holding the scope probe in my hand. Well... since it's a holiday weekend, it's time to break out the Beagles and Teensys and do some experiments. It's just that I don't like E field sensors (if for no other reason than High Z amplifiers get destroyed by ESD).. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
Bob, Several of us do long-term measurement of mains frequency. We tend to time-stamp cycles and then compute period or frequency, rather than measuring frequency or period directly. Traditional counters in gated frequency or time interval mode have dead time and this will skew results. In my case I just run a 5 VAC wall-wart through a 10k resistor directly to the input pin of a PIC. No scaling, no filtering, no opto, no ZCD, no nothing. If I measure every cycle I get 155 million samples per month. If I extract one cycle each second (decimate by 60) it's only 2.5 million samples a month. Many months there is not a single glitch in the data in spite of all the FUD about power line noise. Once in a while a month contains an extra or missing sample but the beauty of timestamp data is that this can be detected and repaired as part of data processing with no loss of phase. Here's a page where Kevin (in New Mexico) and I (in Seattle) both used picPET's to measure mains for a few days and then we compared the results. Although thousands of miles apart, we're both on the same grid so the agreement was astonishing. It was milliseconds in time and ADEV down to e-8 over a day: http://leapsecond.com/pages/mains-cv/ See also: http://leapsecond.com/pic/mains-adev-mdev-gnuplot-g4.png /tvb On 7/2/2019 10:09 PM, Bob Albert via time-nuts wrote: I have tried to measure the power line frequency with spotty success. My best results came from a period measurement, as many periods as the counter can accumulate. Due to noise, one is never sure at quite what point the source is measured. Perhaps a brick wall filter would clean it up for a more reliable measurement. Of course, at 60 Hz the period is 16-2/3 milliseconds. So the counter should properly show a 1 followed by a row of 6s, with the last digit bouncing between 6 and 7 most of the time. If there is a filter used, it will not only remove noise but also short term variations. But generatlly speaking you don't want to measure those, unless you are trying to evaluate a rotary generator. Getting this reading can be a challenge. On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux wrote: On 7/2/19 4:09 PM, Dana Whitlow wrote: I've always noted that casual attempts to pick up 60 Hz with small antennas etc see more harmonics and other trash than actual line frequency. But if you're in an office environment, why not plug something in? It's quite easy to build a simple passive diode clipper/filter that will plug into a wall outlet and which will provide a sort of soft (but clean) squarewave at a voltage level convenient for lab instruments and with good protection against big spikes and other trash riding on the line. Safety approvals are one obstacle (of course one could use a AC wall wart). Actually, it's because someone asked me about a science experiment where you'd place them in a neighborhood outdoors. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] TimeLab phase difference (slope sec/sec)
> I'm just curious if the phase difference slope value can be plugged in to this equation. > I'm seeing 4.22E-12 as the slope value in the upper right of the > TimeLab phase difference plot. Is that telling me that my DUT is > within +4.22ps / sec from my reference 1PPS for the 24 hour > measurement duration? > > I have attached a screen capture that will hopefully make its way > through for viewing. Chris, The answer is yes. But let's consider why instead of plugging numbers into equations. Your measurements are not that different from comparing two wrist watches. Since two watches never actually run at the same rate you know that on average one is fast and one is slow, relative to each other. We often measure clock or oscillator rate using a unit-less number like percent. Your left watch may be 0.01% faster than your right watch. Or maybe it's 15 ppm slower, or 50 ppb faster. These are all dimensionless numbers; ratios. So when we talk about an oscillator being 4.22E-12 fast it's just 4.22 ppt, or 0.0004 or 0.0422%. You get the idea. So where does the 4.22 ps/s thing come from? Well, it turns out that the way that we measure two clocks is not to directly compare their frequency. You can't tell with a glance at two wristwatches which is fast and which is slow. Sure, one may be ahead and one may be behind. But that is the time (phase) of the clocks; not their rate. The best way to find out which clock is fast or slow is to compare their times *over a long time*. Eventually a *trend* will be evident. You might have to wait an hour before one watch gets a second ahead of the other. This is where the "second/second" thing comes in. If a watch is fast by 1 second an hour then it must be running 1s/3600s = 0.028% = 278 ppm faster. Note how both the units of the amount of time gain (1 s) and the amount of time spent doing the measurement (3600 s) cancel and you're left with a dimensionless number. In general a frequency difference measurement is just a phase (aka time) difference measurement made over some elapsed time (aka measurement duration). So you are using a TAPR/TICC to measure the phase difference between your two clocks. It appears you ran it for an entire day (1 d = 86400 s) and the net change in phase between the two clocks was 382 ns. That means the frequency difference between the two clocks is 382 ns / 86400 s = 382e-9 / 86400 = 4.22e-012. The reason this wasn't obvious is that you had the TimeLab 'r' (residual) command in effect. In a sense, this removes the very slope you're trying to see. If you undo the 'r' you should see one clock gradually gaining time relative to the other. The advantage of the 'r' command is that it shows you "what's left" if the two clocks were running at the same rate; it shows the wander, the short- and mid-term noise between the two. And TimeLab also reports the now-removed slope in the upper corner. Now back to 4.22 ps/s. It is true that 4.22e-12 is equal to 4.22 ps/s. Mathematically, it is also equal to 382 ns/d, or 133 us/year for that matter. Yet, it may be misleading to claim 133 us/year because the word "year" may be interpreted as how long the measurement was. But it wasn't a year-long experiment, not even close. Similarly, claiming the clock is 4.22 ps/s may imply to the reader that both the DUT and the REF and the TICC are all clean signals at the sub-ps level. But they aren't, not even close. To complete the picture you need both the frequency difference value and the duration over which the measurement was made. So that's why you often see frequency differences reported using scientific notation, as in 4.22e-12, rather than ps/s or ns/d or us/y. /tvb ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
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 far easier to plug in an AC wall wart. Tim N3QE On Wed, Jul 3, 2019 at 1:01 AM jimlux wrote: > On 7/2/19 4:09 PM, Dana Whitlow wrote: > > I've always noted that casual attempts to pick up 60 Hz with small > antennas > > etc see more harmonics and other trash than actual line frequency. But > if > > you're in an office environment, why not plug something in? It's quite > easy > > to build a simple passive diode clipper/filter that will plug into a wall > > outlet and > > which will provide a sort of soft (but clean) squarewave at a voltage > level > > convenient for lab instruments and with good protection against big > spikes > > and > > other trash riding on the line. > > > Safety approvals are one obstacle (of course one could use a AC wall wart). > > Actually, it's because someone asked me about a science experiment where > you'd place them in a neighborhood outdoors. > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] TimeLab phase difference (slope sec/sec)
Chris, Ok, one source is a PRS-10. Is it the DUT or the reference? And if it's the DUT, what is the reference source? Dana On Tue, Jul 2, 2019 at 8:00 PM Chris Burford wrote: > Hi Bob, > > I'm seeing 4.22E-12 as the slope value in the upper right of the TimeLab > phase difference plot. Is that telling me that my DUT is within +4.22ps > / sec from my reference 1PPS for the 24 hour measurement duration? > > I have attached a screen capture that will hopefully make its way > through for viewing. > > Thanks, > > Chris > > On 07/02/19 11:50:10, Bob kb8tq wrote: > > Hi > > > > The difference in seconds between the start phase and the end phase > divided by the number > > of seconds duration gives you the parts in whatever of the error. > > > > If you see 1us ( = 1x10^-6 seconds) of change in a second, you are off > by 1 ppm (or 1x10^-6). > > If you see 1 us of change in 1,000 seconds you are off by 1 ppb (or > 1x10^-9). At a bit over 10 > > days (1,000,000 seconds) your 1 us change is 1 ppt (or 1x10^-12). > > > > Bob > > > >> On Jul 2, 2019, at 10:17 AM, Chris Burford > wrote: > >> > >> Is the slope value for the phase difference shown in TimeLab an average > of the overall data sample duration? The reason I ask is that my service > manual for my RFS says: > >> > >> /"//A faster way to make the comparison between the reference frequency > and the DUT is to use the time interval measurement mode of the counters. > In this case, the time intervals between the 10MHz zero crossings of the > reference frequency and the DUT are measured and averaged. If this time > interval changes by less than 10ps per second, then the DUT is within 1 > part in //10^11 of the frequency reference."/ > >> > >> I'm just curious if the phase difference slope value can be plugged in > to this equation. > >> > >> Regards, > >> > >> Chris > >> > >> > >> ___ > >> time-nuts mailing list --time-nuts@lists.febo.com > >> To unsubscribe, go tohttp:// > lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > > ___ > > time-nuts mailing list --time-nuts@lists.febo.com > > To unsubscribe, go tohttp:// > lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] TimeLab phase difference (slope sec/sec)
Hi Bob, I'm seeing 4.22E-12 as the slope value in the upper right of the TimeLab phase difference plot. Is that telling me that my DUT is within +4.22ps / sec from my reference 1PPS for the 24 hour measurement duration? I have attached a screen capture that will hopefully make its way through for viewing. Thanks, Chris == Chris, Just looking at the graph reminds me of a daily variation - perhaps due to temperature. Is that likely? Would a two-day graph be worth doing in this particular case? Cheers, David -- SatSignal Software - Quality software for you Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
On 7/2/19 10:09 PM, Bob Albert via time-nuts wrote: I have tried to measure the power line frequency with spotty success. My best results came from a period measurement, as many periods as the counter can accumulate. Due to noise, one is never sure at quite what point the source is measured. Perhaps a brick wall filter would clean it up for a more reliable measurement. Of course, at 60 Hz the period is 16-2/3 milliseconds. So the counter should properly show a 1 followed by a row of 6s, with the last digit bouncing between 6 and 7 most of the time. If there is a filter used, it will not only remove noise but also short term variations. But generatlly speaking you don't want to measure those, unless you are trying to evaluate a rotary generator. Getting this reading can be a challenge. The idea would be to look at the phase variations over time across a neighborhood and see if you can see effects from people turning on and off loads (air conditioners and sags causing light flicker brought up the discussion). It's a whole lot easier for someone to ask "can I put this little recording box here" than "can I plug something into your wall socket" The idea is that you get cheap GPS receivers as the time hack and record *something* at a suitable rate after some low pass filtering, and then post process. 1kHz sample rate for a day is 86 Megasamples, so it's not an enormous dataset that needs to be recorded. Maybe it's just time [sic] for an experiment - stick a wire on an ADC on a Beagle or Arduino and make some recordings. On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux wrote: On 7/2/19 4:09 PM, Dana Whitlow wrote: I've always noted that casual attempts to pick up 60 Hz with small antennas etc see more harmonics and other trash than actual line frequency. But if you're in an office environment, why not plug something in? It's quite easy to build a simple passive diode clipper/filter that will plug into a wall outlet and which will provide a sort of soft (but clean) squarewave at a voltage level convenient for lab instruments and with good protection against big spikes and other trash riding on the line. Safety approvals are one obstacle (of course one could use a AC wall wart). Actually, it's because someone asked me about a science experiment where you'd place them in a neighborhood outdoors. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
jim...@earthlink.net said: > Actually, it's because someone asked me about a science experiment where > you'd place them in a neighborhood outdoors. Sounds like another science experiment: build an antenna to pick up 60 Hz. You could start with the typical ferrite, coil, and cap. Just adjust the cap to your new target frequency. Simple to try. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
I'd normally use an optocoupler. But it doesn't need to be an 8-pin dip with the mains and low-voltage pins 0.3" apart - it can be a neon lamp and a photodiode, or a photodiode near a mains-fed lamp. Even an incandescent has a very strong modulation of the light. You just need to avoid leds that have smoothed DC, and flourescents with HF ballasts. On Wed, Jul 3, 2019 at 7:00 AM Bob Albert via time-nuts < time-nuts@lists.febo.com> wrote: > I have tried to measure the power line frequency with spotty success. My > best results came from a period measurement, as many periods as the counter > can accumulate. Due to noise, one is never sure at quite what point the > source is measured. Perhaps a brick wall filter would clean it up for a > more reliable measurement. > Of course, at 60 Hz the period is 16-2/3 milliseconds. So the counter > should properly show a 1 followed by a row of 6s, with the last digit > bouncing between 6 and 7 most of the time. > If there is a filter used, it will not only remove noise but also short > term variations. But generatlly speaking you don't want to measure those, > unless you are trying to evaluate a rotary generator. > Getting this reading can be a challenge. > On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux < > jim...@earthlink.net> wrote: > > On 7/2/19 4:09 PM, Dana Whitlow wrote: > > I've always noted that casual attempts to pick up 60 Hz with small > antennas > > etc see more harmonics and other trash than actual line frequency. But > if > > you're in an office environment, why not plug something in? It's quite > easy > > to build a simple passive diode clipper/filter that will plug into a wall > > outlet and > > which will provide a sort of soft (but clean) squarewave at a voltage > level > > convenient for lab instruments and with good protection against big > spikes > > and > > other trash riding on the line. > > > Safety approvals are one obstacle (of course one could use a AC wall wart). > > Actually, it's because someone asked me about a science experiment where > you'd place them in a neighborhood outdoors. > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 60 Hz frequency and phase measurement
I have tried to measure the power line frequency with spotty success. My best results came from a period measurement, as many periods as the counter can accumulate. Due to noise, one is never sure at quite what point the source is measured. Perhaps a brick wall filter would clean it up for a more reliable measurement. Of course, at 60 Hz the period is 16-2/3 milliseconds. So the counter should properly show a 1 followed by a row of 6s, with the last digit bouncing between 6 and 7 most of the time. If there is a filter used, it will not only remove noise but also short term variations. But generatlly speaking you don't want to measure those, unless you are trying to evaluate a rotary generator. Getting this reading can be a challenge. On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux wrote: On 7/2/19 4:09 PM, Dana Whitlow wrote: > I've always noted that casual attempts to pick up 60 Hz with small antennas > etc see more harmonics and other trash than actual line frequency. But if > you're in an office environment, why not plug something in? It's quite easy > to build a simple passive diode clipper/filter that will plug into a wall > outlet and > which will provide a sort of soft (but clean) squarewave at a voltage level > convenient for lab instruments and with good protection against big spikes > and > other trash riding on the line. Safety approvals are one obstacle (of course one could use a AC wall wart). Actually, it's because someone asked me about a science experiment where you'd place them in a neighborhood outdoors. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
