Re: [time-nuts] Mains frequency (Tom Van Baak)
Tom - I just had to comment--- Both assume some reasonable limit of mains df/f/dt. You can either do it with a fancy $100 to $1000 reference signal generator + PLL or FLL + IQ detector + professional box -- or with a $1 PIC and $0 s/w. /tvb You are of course correct. However I would most humbly point out that the cost of software is not zero if the time-nutter places any value on his or her time. If you figure your engineering direct labor rate is, for example $ 40 per hour, and the job takes 15 hours to program - you just blew $ 600 of your life. That assumes no issues crop up. Now as a private consultant or as a business that direct labor will be burdened with say about 130% overhead. So we are talking real money in terms of the value of your time. As a hobbyist you can contribute the time for free - but do under appreciate its value. For an olde hardware guy like me (who can sorta program a PIC) a known harware approach causes me less fear and feeling of dread than the PIC approach. So we do what we are more comfortable with. Enjoyable discussion though. -73 john k6iql ___ 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] Mains frequency
This resonates with me somewhat since I used to run nuclear power plants and operate the actual turbines. It does seem that the time interval measurements have much more jitter than I would expect. I suspect the thousands of turbines phase locked may introduce all kinds of very subtle variations. I do know when you put a submarine turbine on shore power (grid). You no longer have to control speed... The grid does that for you. Sent from my iPad > On Nov 16, 2013, at 9:35 PM, Charles Steinmetz wrote: > > tvb wrote: > >> I think we agree. Just to clarify... >> >> I rely on no hardware and no software filters when I use a time-stamping >> counter such as a sub-nanosecond Pendulum CNT-9x or sub-microsecond picPET. >> An electrical zero-crossing happens when it happens. If you "filter" you're >> just trying to change history: spikes are spikes; noise is noise; history is >> history. Deal with it. Record it, don't filter it away. > > Well, it depends on what one wants to investigate. The "naked" history one > captures with no filtering may not be the cleanest history available of the > phenomenon under investigation. Except in unusual circumstances, mains > voltage is generated by massive rotating machinery -- so anything fast that > happens on your incoming mains voltage is not a reflection of the grid > frequency. If what you want to know is the grid frequency over time (vector > sum of the rotational velocity of the various generators on the grid, as seen > from your location), a filtered and limited signal may (probably will) > provide the best assessment. Note that local zero crossings are only a proxy > for grid frequency to begin with -- and not a very good one, specifically > because of the high noise level. Of course, you can always filter in > software if you time-stamp each zero cross in all its naked glory, but > removing the noise prior to time-stamping is often preferable to digitally > processing a noisy capture. > > Put another way, the massive rotating machinery that generates the mains > voltage can only change the zero cross of the grid by a tiny amount from one > cycle to the next. If a data capture method shows cycle-to-cycle jitter that > is significantly greater than this amount, the increase cannot be due to the > generators, it can only be due to noise. If one's interest is the grid > frequency, removing this noise prior to time-stamping can only help. > > Note that I'm not talking about a filter Q in the millions -- I'd probably be > inclined to use a linear-phase filter with several Hz bandwidth, after a more > rigorous analysis of the application. > >> You can either focus on the signal, or the noise. That's two separate plots. > > Agreed. If you are investigating incidental noise on the mains rather than > the grid frequency, then the signal you capture needs to be at least as > broadband as the noise in which you are interested. > > Since I do not use the actual local mains zero crossings for anything (other > than electronically switching loads on at zero voltage and off at zero > current, where absolute timing is irrelevant), I'm not sure why one might be > interested in characterizing them. OTOH, since I do have equipment that > responds to the grid frequency, I can see practical utility in characterizing > that. Hence my suggestion to filter. > > 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] Mains frequency
tvb wrote: I think we agree. Just to clarify... I rely on no hardware and no software filters when I use a time-stamping counter such as a sub-nanosecond Pendulum CNT-9x or sub-microsecond picPET. An electrical zero-crossing happens when it happens. If you "filter" you're just trying to change history: spikes are spikes; noise is noise; history is history. Deal with it. Record it, don't filter it away. Well, it depends on what one wants to investigate. The "naked" history one captures with no filtering may not be the cleanest history available of the phenomenon under investigation. Except in unusual circumstances, mains voltage is generated by massive rotating machinery -- so anything fast that happens on your incoming mains voltage is not a reflection of the grid frequency. If what you want to know is the grid frequency over time (vector sum of the rotational velocity of the various generators on the grid, as seen from your location), a filtered and limited signal may (probably will) provide the best assessment. Note that local zero crossings are only a proxy for grid frequency to begin with -- and not a very good one, specifically because of the high noise level. Of course, you can always filter in software if you time-stamp each zero cross in all its naked glory, but removing the noise prior to time-stamping is often preferable to digitally processing a noisy capture. Put another way, the massive rotating machinery that generates the mains voltage can only change the zero cross of the grid by a tiny amount from one cycle to the next. If a data capture method shows cycle-to-cycle jitter that is significantly greater than this amount, the increase cannot be due to the generators, it can only be due to noise. If one's interest is the grid frequency, removing this noise prior to time-stamping can only help. Note that I'm not talking about a filter Q in the millions -- I'd probably be inclined to use a linear-phase filter with several Hz bandwidth, after a more rigorous analysis of the application. You can either focus on the signal, or the noise. That's two separate plots. Agreed. If you are investigating incidental noise on the mains rather than the grid frequency, then the signal you capture needs to be at least as broadband as the noise in which you are interested. Since I do not use the actual local mains zero crossings for anything (other than electronically switching loads on at zero voltage and off at zero current, where absolute timing is irrelevant), I'm not sure why one might be interested in characterizing them. OTOH, since I do have equipment that responds to the grid frequency, I can see practical utility in characterizing that. Hence my suggestion to filter. 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] Mains frequency
"Turns out that professional gear for this does not do time-stamping in this regard. Rather, they I-Q demodulate the signal with a reference signal at the nominal rate, low-pass filter it and pay attention to details of filtering like group-delay and compensation thereof." It makes sense to me. That way, you use the entire signal instead of just the zero crossing. You know that the signal is generated as a sine wave. Therefore, essentially you synthesize a local sine wave that is a best fit to the input signal and you measure the zero crossings of the synthesized signal. Didier KO4BB Magnus Danielson wrote: >Tom, > >On 11/17/2013 03:02 AM, Tom Van Baak wrote: >> Charles, et al. >> >> I think we agree. Just to clarify... >> >> I rely on no hardware and no software filters when I use a >time-stamping counter such as a sub-nanosecond Pendulum CNT-9x or >sub-microsecond picPET. An electrical zero-crossing happens when it >happens. If you "filter" you're just trying to change history: spikes >are spikes; noise is noise; history is history. Deal with it. Record >it, don't filter it away. >> >> The beauty of the time-stamping method is that you capture any and >all positive zero-crossings. If there is "noise" all it does is create >unexpected and obvious artificial too-early or too-late samples -- >which are trivial to analyze or eliminate in software. >> >> Some call them "outliers" and ignore them. This is correct. However, >if one "filters" or "averages" them, you give validity they may not >deserve. Bogus data should be eliminated by *logic*, not attenuated >with pseudo-analog *filtering*. >> >> You can either focus on the signal, or the noise. That's two separate >plots. An extraneous time-stamp happens to me a couple times a month; >they are easy to spot and ignore. Similarly, a couple times a year I >might miss a 60 Hz sample; these are also easy to spot and repair. For >best time & frequency results, never "divide by =60"; instead "decimate >by ~1 second". >Standard wide-bandwidth counters isn't really ideal for signals like >this. > >When you measure the mains signal, nominally 60 Hz in this case, spikes >etc. is noise which is local and not of interest when comparing over a >large area. Inter-area oscillations have much slower properties. >If you go the time-stamping way, you *should* remove such noise. > >Removing or padding over it by logic will mean dropping data, which is >not helpful. > >Turns out that professional gear for this does not do time-stamping in >this regard. Rather, they I-Q demodulate the signal with a reference >signal at the nominal rate, low-pass filter it and pay attention to >details of filtering like group-delay and compensation thereof. It's a >rather wise approach for the type of conditions you have. > >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. -- Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things. ___ 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] Mains frequency
Does an ac transformer hurt me? I was looking for that dang megohm page when I started this. Couldn't find it so I used a transformer. Doc Sent from my iPad On Nov 16, 2013, at 9:17 PM, "Tom Van Baak" wrote: >> Again, why are you measuring the AC line? I'd think maybe to measure the >> noise that is on it. The fundamental freq. changes second by second. >> It's not a clean 60Hz my any means. The rate of frequency change is one >> thing you'd like to measure >> >> I was just watching a minute ago and can see a 0.01Hz/second drift. It is >> likely MUCH worse as what I was watching is filtered over second > > Chris, > > No, forget the noise (it's actually quite clean: look at it sometime). > > We measure mains because we can. > > We also measure it because millions of wall-clocks are based on mains > frequency; it was the original "GPSDO". > > We measure it because its phase plot, frequency histogram, and ADEV plot are > really quite interesting. > > We measure it because Seattle, WA (tvb) and New Mexico (Kevin) are both on > the same grid and mutually agree to 10 microseconds (!) over an hour even > though they can both wander by many seconds relative to UTC. It's a textbook > example of common view time transfer. See also: > http://leapsecond.com/pages/mains/ > http://leapsecond.com/pages/ac-detect/ > > You too can join the mains party. Measure it with your own method, or a fancy > TrueTime time/frequency deviation meter (TFDM) or use something simple like a > picPET (http://www.leapsecond.com/pic/picpet.htm) or Arduino or even a > NTP/Linux/serial DCD pin hack. > > /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] Mains frequency filter
For a non Time-Nuts application, I needed a narrow bandpass filter that would provide essentially zero phase shift (no more than 10 or 20uS was desired) over a frequency range of 55 to 65 Hz while providing useful reduction of the harmonics, particularly in the range of 400 to 1kHz. This was to filter the line voltage. I needed an output that was a clean sine wave but with essentially no phase or amplitude error compared to the input signal, even when the input signal changed in frequency. Of course, there is no "conventional" filter topology that will provide zero phase shift over a range of frequency, you will be lucky to find one that provides zero phase shift at ONE frequency. I knew the switched capacitor filter could be set to provide zero phase shift near the center frequency, but the phase shift would change rapidly when the input frequency changed, like any other filter. I came across the LTC1060 and I found out that when driving its clock from a PLL that multiplies the line frequency by the proper factor (50 or 100 for the LTC1060), a single potentiometer can then be used to adjust the phase shift to zero nominally, and the phase shift remains below a few uS over the range I was interested in. Being a switched capacitor filter, it can be made as narrow as desired without affecting the other characteristics too much. Reading this thread, I just realized that this filter would be very useful to filter the 60Hz before feeding a counter for the purpose of measuring the line frequency and phase without being too much affected by noise and other disturbances. Didier KO4BB Charles Steinmetz wrote: >Chuck wrote: > >>In the case of a 60Hz mains derived signal, most of the noise is >>going to be riding on the signal, and will be amplified with your >>gain stage. > >The potential evils of bandpass filters in a timing chain are well >known, but as long as you can accept the delay of a filter (or >correct for it, which should be trivial with a PIC or other uC), you >may be much further ahead with a noisy signal like the AC mains if >you use a sharp bandpass filter on the incoming 60 Hz then amplify & >clip the signal to increase the slew rate. Active filters with fast, >quiet op-amps should do the job well. For the lowest jitter, a >Collins-style multi-stage zero cross detector may be helpful. > >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. -- Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things. ___ 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] Mains frequency
> Again, why are you measuring the AC line? I'd think maybe to measure the > noise that is on it. The fundamental freq. changes second by second. > It's not a clean 60Hz my any means. The rate of frequency change is one > thing you'd like to measure > > I was just watching a minute ago and can see a 0.01Hz/second drift. It is > likely MUCH worse as what I was watching is filtered over second Chris, No, forget the noise (it's actually quite clean: look at it sometime). We measure mains because we can. We also measure it because millions of wall-clocks are based on mains frequency; it was the original "GPSDO". We measure it because its phase plot, frequency histogram, and ADEV plot are really quite interesting. We measure it because Seattle, WA (tvb) and New Mexico (Kevin) are both on the same grid and mutually agree to 10 microseconds (!) over an hour even though they can both wander by many seconds relative to UTC. It's a textbook example of common view time transfer. See also: http://leapsecond.com/pages/mains/ http://leapsecond.com/pages/ac-detect/ You too can join the mains party. Measure it with your own method, or a fancy TrueTime time/frequency deviation meter (TFDM) or use something simple like a picPET (http://www.leapsecond.com/pic/picpet.htm) or Arduino or even a NTP/Linux/serial DCD pin hack. /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.
Re: [time-nuts] Mains frequency
> When you measure the mains signal, nominally 60 Hz in this case, spikes > etc. is noise which is local and not of interest when comparing over a > large area. Inter-area oscillations have much slower properties. > If you go the time-stamping way, you *should* remove such noise. > > Removing or padding over it by logic will mean dropping data, which is > not helpful. A time-stamping counter never drops *data*; instead you apply logic to drop *noise* when necessary. > Turns out that professional gear for this does not do time-stamping in > this regard. Rather, they I-Q demodulate the signal with a reference > signal at the nominal rate, low-pass filter it and pay attention to > details of filtering like group-delay and compensation thereof. It's a > rather wise approach for the type of conditions you have. I'd be happy to compare "professional gear" with a time-stamping counter. I have two or three years of data to show 60 Hz time-stamping works perfectly. Not to say your professional gear might also. But a zero-crossing counter never misses a cycle; you can set the s/w bandwidth just as you can set an IQ hardware bandwidth. Both assume some reasonable limit of mains df/f/dt. You can either do it with a fancy $100 to $1000 reference signal generator + PLL or FLL + IQ detector + professional box -- or with a $1 PIC and $0 s/w. /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.
Re: [time-nuts] Mains frequency
On 11/17/2013 03:33 AM, Chris Albertson wrote: > Again, why are you measuring the AC line? I'd think maybe to measure the > noise that is on it. The fundamental freq. changes second by second. > It's not a clean 60Hz my any means. The rate of frequency change is one > thing you'd like to measure > > I was just watching a minute ago and can see a 0.01Hz/second drift. It is > likely MUCH worse as what I was watching is filtered over second The phase of it tells you a lot about the powergrid, especially when you collect data over the full power-grid and at sufficiently high rate. 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] Mains frequency
Again, why are you measuring the AC line? I'd think maybe to measure the noise that is on it. The fundamental freq. changes second by second. It's not a clean 60Hz my any means. The rate of frequency change is one thing you'd like to measure I was just watching a minute ago and can see a 0.01Hz/second drift. It is likely MUCH worse as what I was watching is filtered over second On Sat, Nov 16, 2013 at 4:54 PM, Charles Steinmetz wrote: > Chuck wrote: > > In the case of a 60Hz mains derived signal, most of the noise is >> going to be riding on the signal, and will be amplified with your >> gain stage. >> > > The potential evils of bandpass filters in a timing chain are well known, > but as long as you can accept the delay of a filter (or correct for it, > which should be trivial with a PIC or other uC), you may be much further > ahead with a noisy signal like the AC mains if you use a sharp bandpass > filter on the incoming 60 Hz then amplify & clip the signal to increase the > slew rate. Active filters with fast, quiet op-amps should do the job well. > For the lowest jitter, a Collins-style multi-stage zero cross detector may > be helpful. > > 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. > -- Chris Albertson Redondo Beach, California ___ 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] Mains frequency
Tom, On 11/17/2013 03:02 AM, Tom Van Baak wrote: > Charles, et al. > > I think we agree. Just to clarify... > > I rely on no hardware and no software filters when I use a time-stamping > counter such as a sub-nanosecond Pendulum CNT-9x or sub-microsecond picPET. > An electrical zero-crossing happens when it happens. If you "filter" you're > just trying to change history: spikes are spikes; noise is noise; history is > history. Deal with it. Record it, don't filter it away. > > The beauty of the time-stamping method is that you capture any and all > positive zero-crossings. If there is "noise" all it does is create unexpected > and obvious artificial too-early or too-late samples -- which are trivial to > analyze or eliminate in software. > > Some call them "outliers" and ignore them. This is correct. However, if one > "filters" or "averages" them, you give validity they may not deserve. Bogus > data should be eliminated by *logic*, not attenuated with pseudo-analog > *filtering*. > > You can either focus on the signal, or the noise. That's two separate plots. > An extraneous time-stamp happens to me a couple times a month; they are easy > to spot and ignore. Similarly, a couple times a year I might miss a 60 Hz > sample; these are also easy to spot and repair. For best time & frequency > results, never "divide by =60"; instead "decimate by ~1 second". Standard wide-bandwidth counters isn't really ideal for signals like this. When you measure the mains signal, nominally 60 Hz in this case, spikes etc. is noise which is local and not of interest when comparing over a large area. Inter-area oscillations have much slower properties. If you go the time-stamping way, you *should* remove such noise. Removing or padding over it by logic will mean dropping data, which is not helpful. Turns out that professional gear for this does not do time-stamping in this regard. Rather, they I-Q demodulate the signal with a reference signal at the nominal rate, low-pass filter it and pay attention to details of filtering like group-delay and compensation thereof. It's a rather wise approach for the type of conditions you have. 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] Loran
lfphoenix is still on the air. It has not gone down as of 0212 utc. Regards Paul WB8TSL/ Boston On Sat, Nov 16, 2013 at 8:23 PM, Brian Lloyd wrote: > On Sat, Nov 16, 2013 at 7:04 PM, Bill Riches >wrote: > > > Wildwood is still up at 0100 z 11/17. Guess they are running all > weekend. > > > > Looks like it is off the air again. > > -- > 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. > ___ 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] Mains frequency
Charles, et al. I think we agree. Just to clarify... I rely on no hardware and no software filters when I use a time-stamping counter such as a sub-nanosecond Pendulum CNT-9x or sub-microsecond picPET. An electrical zero-crossing happens when it happens. If you "filter" you're just trying to change history: spikes are spikes; noise is noise; history is history. Deal with it. Record it, don't filter it away. The beauty of the time-stamping method is that you capture any and all positive zero-crossings. If there is "noise" all it does is create unexpected and obvious artificial too-early or too-late samples -- which are trivial to analyze or eliminate in software. Some call them "outliers" and ignore them. This is correct. However, if one "filters" or "averages" them, you give validity they may not deserve. Bogus data should be eliminated by *logic*, not attenuated with pseudo-analog *filtering*. You can either focus on the signal, or the noise. That's two separate plots. An extraneous time-stamp happens to me a couple times a month; they are easy to spot and ignore. Similarly, a couple times a year I might miss a 60 Hz sample; these are also easy to spot and repair. For best time & frequency results, never "divide by =60"; instead "decimate by ~1 second". /tvb - Original Message - From: "Charles Steinmetz" To: "Discussion of precise time and frequency measurement" Sent: Saturday, November 16, 2013 4:54 PM Subject: Re: [time-nuts] Mains frequency > Chuck wrote: > >>In the case of a 60Hz mains derived signal, most of the noise is >>going to be riding on the signal, and will be amplified with your >>gain stage. > > The potential evils of bandpass filters in a timing chain are well > known, but as long as you can accept the delay of a filter (or > correct for it, which should be trivial with a PIC or other uC), you > may be much further ahead with a noisy signal like the AC mains if > you use a sharp bandpass filter on the incoming 60 Hz then amplify & > clip the signal to increase the slew rate. Active filters with fast, > quiet op-amps should do the job well. For the lowest jitter, a > Collins-style multi-stage zero cross detector may be helpful. > > 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] Loran
On Sat, Nov 16, 2013 at 7:04 PM, Bill Riches wrote: > Wildwood is still up at 0100 z 11/17. Guess they are running all weekend. > Looks like it is off the air again. -- 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] Loran
Wildwood is still up at 0100 z 11/17. Guess they are running all weekend. 73, Bill, WA2DVU Cape May, NJ ___ 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] Mains frequency
Chuck wrote: In the case of a 60Hz mains derived signal, most of the noise is going to be riding on the signal, and will be amplified with your gain stage. The potential evils of bandpass filters in a timing chain are well known, but as long as you can accept the delay of a filter (or correct for it, which should be trivial with a PIC or other uC), you may be much further ahead with a noisy signal like the AC mains if you use a sharp bandpass filter on the incoming 60 Hz then amplify & clip the signal to increase the slew rate. Active filters with fast, quiet op-amps should do the job well. For the lowest jitter, a Collins-style multi-stage zero cross detector may be helpful. 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] Mains frequency
Only if the noise in question comes from the trigger electronics. In the case of a 60Hz mains derived signal, most of the noise is going to be riding on the signal, and will be amplified with your gain stage. A -delta amplitude noise signal will be zero when the sine wave signal is at +delta. That will be sometime other than the actual zero crossing... which is phase noise. -Chuck Harris Magnus Danielson wrote: On 11/16/2013 03:13 PM, Chuck Harris wrote: Random noise always converts into time jitter. It doesn't matter how much you amplify the input signal, noise can push the detected zero crossing wherever it wants to. You are missing that you can alter how much trigger jitter you get. Cheers, Magnus -Chuck Harris ___ 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] Loran
HI You can get some pretty crazy propagation at 100 KHz. I suspect they will have to keep the basic modulation close enough to a proper Loran signal or it will create major headaches internationally. I have not dug out the ppt. Do they list station locations yet? Bob On Nov 16, 2013, at 6:27 PM, paul swed wrote: > Well indeed interesting updates to the ppt. Most of it is the same as the > earlier decks I have seen so far. Though what I did find interesting is > they now mention navigation and not just PNT. I will guess with the 4 site > senario they are back in the navigation business. There is also a small > note on one slide the coast guard has no interest in supporting this. I > think thats with respect to maintaining the sites. Someones going to have > to pay to stabilize those massive lightning arresters. > > As to the monopoly thats been a thread that's run its course about wwvbs > new phase modulation. > > I will say this as I have listened to the actual signal it is there but not > as loud as I seem to recall. Also I imagine I am hearing almost a > continuous GRI as if the whole period is used. No real gaps. Would need to > actually look at the signal with a scope. Signal levels are good so I can't > complain and the rcvrs are happy. > This has been the longest I have had lfphoenix in a number of years. > Sure hope that it will stick around in a usable fashion. If it does I > really need to explore a better antenna. I am using the classic boat > antenna and preamp. I will believe a loop antenna that has a low Q might be > quite useful. Comments appreciated. > Regards > Paul > WB8TSL > > > > > > On Fri, Nov 15, 2013 at 11:33 PM, Dennis Ferguson < > dennis.c.fergu...@gmail.com> wrote: > >> >> On 15 Nov, 2013, at 19:12 , Bob Camp wrote: >>> We probably could agree on Seneca NY since that’s about equal distance >> to the pair of us. >>> >>> Does anybody know the proposed ERP on the new system? Some of the >> master’s on the China chains are pretty high power if I remember correctly. >> >> This powerpoint presentation >> >>http://www.tinyurl.com/l2humtb >> >> says the NL40 transmitter they just bought is 300 kW. >> >> I thought a lot of the Asian chains, including China, used >> Megapulse equipment like the US. I think Megapulse did use >> to say their transmitters were multi-Megawatt, but I can't >> check that since >> >>http://www.megapulse.com >> >> now goes someplace else. >> >> I wonder whether the last bit means that Megapulse is now out >> of the transmitter business for good, or if Ursanav's infatuation >> for the Nautel transmitters is just a passing fancy while they >> complete their vertically integrated monopoly. >> >> Dennis Ferguson >> ___ >> 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] Loran
Well indeed interesting updates to the ppt. Most of it is the same as the earlier decks I have seen so far. Though what I did find interesting is they now mention navigation and not just PNT. I will guess with the 4 site senario they are back in the navigation business. There is also a small note on one slide the coast guard has no interest in supporting this. I think thats with respect to maintaining the sites. Someones going to have to pay to stabilize those massive lightning arresters. As to the monopoly thats been a thread that's run its course about wwvbs new phase modulation. I will say this as I have listened to the actual signal it is there but not as loud as I seem to recall. Also I imagine I am hearing almost a continuous GRI as if the whole period is used. No real gaps. Would need to actually look at the signal with a scope. Signal levels are good so I can't complain and the rcvrs are happy. This has been the longest I have had lfphoenix in a number of years. Sure hope that it will stick around in a usable fashion. If it does I really need to explore a better antenna. I am using the classic boat antenna and preamp. I will believe a loop antenna that has a low Q might be quite useful. Comments appreciated. Regards Paul WB8TSL On Fri, Nov 15, 2013 at 11:33 PM, Dennis Ferguson < dennis.c.fergu...@gmail.com> wrote: > > On 15 Nov, 2013, at 19:12 , Bob Camp wrote: > > We probably could agree on Seneca NY since that’s about equal distance > to the pair of us. > > > > Does anybody know the proposed ERP on the new system? Some of the > master’s on the China chains are pretty high power if I remember correctly. > > This powerpoint presentation > > http://www.tinyurl.com/l2humtb > > says the NL40 transmitter they just bought is 300 kW. > > I thought a lot of the Asian chains, including China, used > Megapulse equipment like the US. I think Megapulse did use > to say their transmitters were multi-Megawatt, but I can't > check that since > > http://www.megapulse.com > > now goes someplace else. > > I wonder whether the last bit means that Megapulse is now out > of the transmitter business for good, or if Ursanav's infatuation > for the Nautel transmitters is just a passing fancy while they > complete their vertically integrated monopoly. > > Dennis Ferguson > ___ > 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] Mains frequency
There is no higher purpose actually. I just fiddle. This is how I relax. On Sat, Nov 16, 2013 at 3:47 PM, Chris Albertson wrote: > No, I meant the purpose of the whole thing. Why are you measuring power > frequency? Not why are you using a PIC.How will the data be used, what > is the question driving the measurement? > > > On Sat, Nov 16, 2013 at 11:23 AM, Bill Dailey wrote: > > > My purpose is to do it with a picpet. That's it. So, that eliminates a > > bunch of the options. I can decouple the measurements from the pc clock > > that way. > > > > Doc > > > > Sent from mobile > > > > > On Nov 16, 2013, at 11:26 AM, Chris Albertson < > albertson.ch...@gmail.com> > > wrote: > > > > > > The signal is 120 volts. You hardly need to amplify it. Clip it with > a > > > diode to +- 9 volts so as not to blow up your serial port. But I'd > use a > > > transformer for safety. The zero crossing detectors are built into the > > > RS232 interface.You take advantage of the RS232 spec which has a > DCD > > > pin input of about +-9 volts that is already set up to find a leading > > edge > > > of a pulse and cause a very low latency interrupt. The system software > > > already will capture the time all inside a kernel level interrupt > > handler. > > > > > > The jitter turns out to be on the order of a single digit microseconds. > > > Good enough for measuring a 60Hz signal. > > > > > > I guess if you want to see transients depends on the purpose of the > > > experiment. Are you looking at local AC power quality or wanting to > > > measure the grid. The grid is well monitored, just use FNET and you > get > > > real-time data for all of North America. I think the reason for > > measuring > > > it yourself is to see local power quality and things load switching > > inside > > > your own building, that's transients. > > > > > > > > > > > > The other way to measure AC with zero added equipment is to treat it as > > an > > > audio signal and after reducing it to 1 volt run it into an audio > > interface > > > And then use FFT. This will let you see very small spikes and noise. > > It > > > depends again on your purpose for doing this. > > > > > > > > > > > > > > > On Sat, Nov 16, 2013 at 1:18 AM, Magnus Danielson < > > > mag...@rubidium.dyndns.org> wrote: > > > > > >>> On 11/16/2013 09:52 AM, Chris Albertson wrote: > > >>> Your method tosses out a lot of data. You can't see transients. > > Ideally > > >>> rather then record a 1 second average you'd record the time of EVERY > > zero > > >>> crossing. It sounds like a lot of data but not really. You only > > record > > >>> 32 bits 60 times each second. That is 240 bytes per second. > > >> But you want it filtered to avoid the transients. Those are really not > > >> that interesting when you measure the grid. > > >> > > >> Also, if you use the event trigger method you probably want to use an > > >> amplifier to increase the slew-rate such that noise does not convert > > >> into time jitter. > > >> > > >> 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. > > > > > > > > > > > > -- > > > > > > Chris Albertson > > > Redondo Beach, California > > > ___ > > > 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. > > > > > > -- > > Chris Albertson > Redondo Beach, California > ___ > 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. > -- Doc Bill Dailey KXØO ___ 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] Mains frequency
On Sat, Nov 16, 2013 at 09:26:10AM -0800, Chris Albertson wrote: > The signal is 120 volts. You hardly need to amplify it. I tried this a slightly different way. Since there is mains noise everywhere, I made a small loop and connected it to a 3.5mm jack and then plugged that into the mic socket on a sound card. You can get lots of (slightly noisy) samples per second. I took chunks of this data and took the Fourier transform to find the dominant frequency: http://www.maths.tcd.ie/~dwmalone/time/leap2012/#mains but I guess you could filter it and count crossings too? David. ___ 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] Mains frequency
No, I meant the purpose of the whole thing. Why are you measuring power frequency? Not why are you using a PIC.How will the data be used, what is the question driving the measurement? On Sat, Nov 16, 2013 at 11:23 AM, Bill Dailey wrote: > My purpose is to do it with a picpet. That's it. So, that eliminates a > bunch of the options. I can decouple the measurements from the pc clock > that way. > > Doc > > Sent from mobile > > > On Nov 16, 2013, at 11:26 AM, Chris Albertson > wrote: > > > > The signal is 120 volts. You hardly need to amplify it. Clip it with a > > diode to +- 9 volts so as not to blow up your serial port. But I'd use a > > transformer for safety. The zero crossing detectors are built into the > > RS232 interface.You take advantage of the RS232 spec which has a DCD > > pin input of about +-9 volts that is already set up to find a leading > edge > > of a pulse and cause a very low latency interrupt. The system software > > already will capture the time all inside a kernel level interrupt > handler. > > > > The jitter turns out to be on the order of a single digit microseconds. > > Good enough for measuring a 60Hz signal. > > > > I guess if you want to see transients depends on the purpose of the > > experiment. Are you looking at local AC power quality or wanting to > > measure the grid. The grid is well monitored, just use FNET and you get > > real-time data for all of North America. I think the reason for > measuring > > it yourself is to see local power quality and things load switching > inside > > your own building, that's transients. > > > > > > > > The other way to measure AC with zero added equipment is to treat it as > an > > audio signal and after reducing it to 1 volt run it into an audio > interface > > And then use FFT. This will let you see very small spikes and noise. > It > > depends again on your purpose for doing this. > > > > > > > > > > On Sat, Nov 16, 2013 at 1:18 AM, Magnus Danielson < > > mag...@rubidium.dyndns.org> wrote: > > > >>> On 11/16/2013 09:52 AM, Chris Albertson wrote: > >>> Your method tosses out a lot of data. You can't see transients. > Ideally > >>> rather then record a 1 second average you'd record the time of EVERY > zero > >>> crossing. It sounds like a lot of data but not really. You only > record > >>> 32 bits 60 times each second. That is 240 bytes per second. > >> But you want it filtered to avoid the transients. Those are really not > >> that interesting when you measure the grid. > >> > >> Also, if you use the event trigger method you probably want to use an > >> amplifier to increase the slew-rate such that noise does not convert > >> into time jitter. > >> > >> 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. > > > > > > > > -- > > > > Chris Albertson > > Redondo Beach, California > > ___ > > 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. > -- Chris Albertson Redondo Beach, California ___ 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] Mains frequency
No trouble. Easy. I love it. Keeping track of the rolling counters was a hack because I am so far removed from serious programming. Sent from mobile > On Nov 16, 2013, at 1:53 PM, "Tom Van Baak (lab)" wrote: > > Doc, > > I measure mains time & frequency with a picPET all the time. In fact that's > one of the reasons I designed it. If you're having any trouble contact me by > email. > > /tvb (i5s) > >> On Nov 16, 2013, at 11:23 AM, Bill Dailey wrote: >> >> My purpose is to do it with a picpet. That's it. So, that eliminates a >> bunch of the options. I can decouple the measurements from the pc clock >> that way. >> >> Doc >> >> Sent from mobile >> >>> On Nov 16, 2013, at 11:26 AM, Chris Albertson >>> wrote: >>> >>> The signal is 120 volts. You hardly need to amplify it. Clip it with a >>> diode to +- 9 volts so as not to blow up your serial port. But I'd use a >>> transformer for safety. The zero crossing detectors are built into the >>> RS232 interface.You take advantage of the RS232 spec which has a DCD >>> pin input of about +-9 volts that is already set up to find a leading edge >>> of a pulse and cause a very low latency interrupt. The system software >>> already will capture the time all inside a kernel level interrupt handler. >>> >>> The jitter turns out to be on the order of a single digit microseconds. >>> Good enough for measuring a 60Hz signal. >>> >>> I guess if you want to see transients depends on the purpose of the >>> experiment. Are you looking at local AC power quality or wanting to >>> measure the grid. The grid is well monitored, just use FNET and you get >>> real-time data for all of North America. I think the reason for measuring >>> it yourself is to see local power quality and things load switching inside >>> your own building, that's transients. >>> >>> >>> >>> The other way to measure AC with zero added equipment is to treat it as an >>> audio signal and after reducing it to 1 volt run it into an audio interface >>> And then use FFT. This will let you see very small spikes and noise. It >>> depends again on your purpose for doing this. >>> >>> >>> >>> >>> On Sat, Nov 16, 2013 at 1:18 AM, Magnus Danielson < >>> mag...@rubidium.dyndns.org> wrote: >>> > On 11/16/2013 09:52 AM, Chris Albertson wrote: > Your method tosses out a lot of data. You can't see transients. Ideally > rather then record a 1 second average you'd record the time of EVERY zero > crossing. It sounds like a lot of data but not really. You only record > 32 bits 60 times each second. That is 240 bytes per second. But you want it filtered to avoid the transients. Those are really not that interesting when you measure the grid. Also, if you use the event trigger method you probably want to use an amplifier to increase the slew-rate such that noise does not convert into time jitter. 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. >>> >>> >>> >>> -- >>> >>> Chris Albertson >>> Redondo Beach, California >>> ___ >>> 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] Mains frequency
Doc, I measure mains time & frequency with a picPET all the time. In fact that's one of the reasons I designed it. If you're having any trouble contact me by email. /tvb (i5s) > On Nov 16, 2013, at 11:23 AM, Bill Dailey wrote: > > My purpose is to do it with a picpet. That's it. So, that eliminates a > bunch of the options. I can decouple the measurements from the pc clock that > way. > > Doc > > Sent from mobile > >> On Nov 16, 2013, at 11:26 AM, Chris Albertson >> wrote: >> >> The signal is 120 volts. You hardly need to amplify it. Clip it with a >> diode to +- 9 volts so as not to blow up your serial port. But I'd use a >> transformer for safety. The zero crossing detectors are built into the >> RS232 interface.You take advantage of the RS232 spec which has a DCD >> pin input of about +-9 volts that is already set up to find a leading edge >> of a pulse and cause a very low latency interrupt. The system software >> already will capture the time all inside a kernel level interrupt handler. >> >> The jitter turns out to be on the order of a single digit microseconds. >> Good enough for measuring a 60Hz signal. >> >> I guess if you want to see transients depends on the purpose of the >> experiment. Are you looking at local AC power quality or wanting to >> measure the grid. The grid is well monitored, just use FNET and you get >> real-time data for all of North America. I think the reason for measuring >> it yourself is to see local power quality and things load switching inside >> your own building, that's transients. >> >> >> >> The other way to measure AC with zero added equipment is to treat it as an >> audio signal and after reducing it to 1 volt run it into an audio interface >> And then use FFT. This will let you see very small spikes and noise. It >> depends again on your purpose for doing this. >> >> >> >> >> On Sat, Nov 16, 2013 at 1:18 AM, Magnus Danielson < >> mag...@rubidium.dyndns.org> wrote: >> On 11/16/2013 09:52 AM, Chris Albertson wrote: Your method tosses out a lot of data. You can't see transients. Ideally rather then record a 1 second average you'd record the time of EVERY zero crossing. It sounds like a lot of data but not really. You only record 32 bits 60 times each second. That is 240 bytes per second. >>> But you want it filtered to avoid the transients. Those are really not >>> that interesting when you measure the grid. >>> >>> Also, if you use the event trigger method you probably want to use an >>> amplifier to increase the slew-rate such that noise does not convert >>> into time jitter. >>> >>> 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. >> >> >> >> -- >> >> Chris Albertson >> Redondo Beach, California >> ___ >> 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] Mains frequency
On 11/16/2013 03:13 PM, Chuck Harris wrote: > Random noise always converts into time jitter. It doesn't > matter how much you amplify the input signal, noise can push > the detected zero crossing wherever it wants to. You are missing that you can alter how much trigger jitter you get. Cheers, Magnus > > -Chuck Harris > > Magnus Danielson wrote: >> On 11/16/2013 09:52 AM, Chris Albertson wrote: >>> Your method tosses out a lot of data. You can't see transients. >>> Ideally >>> rather then record a 1 second average you'd record the time of EVERY >>> zero >>> crossing. It sounds like a lot of data but not really. You only >>> record >>> 32 bits 60 times each second. That is 240 bytes per second. >> But you want it filtered to avoid the transients. Those are really not >> that interesting when you measure the grid. >> >> Also, if you use the event trigger method you probably want to use an >> amplifier to increase the slew-rate such that noise does not convert >> into time jitter. >> >> 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. >> > ___ > 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] Mains frequency
My purpose is to do it with a picpet. That's it. So, that eliminates a bunch of the options. I can decouple the measurements from the pc clock that way. Doc Sent from mobile > On Nov 16, 2013, at 11:26 AM, Chris Albertson > wrote: > > The signal is 120 volts. You hardly need to amplify it. Clip it with a > diode to +- 9 volts so as not to blow up your serial port. But I'd use a > transformer for safety. The zero crossing detectors are built into the > RS232 interface.You take advantage of the RS232 spec which has a DCD > pin input of about +-9 volts that is already set up to find a leading edge > of a pulse and cause a very low latency interrupt. The system software > already will capture the time all inside a kernel level interrupt handler. > > The jitter turns out to be on the order of a single digit microseconds. > Good enough for measuring a 60Hz signal. > > I guess if you want to see transients depends on the purpose of the > experiment. Are you looking at local AC power quality or wanting to > measure the grid. The grid is well monitored, just use FNET and you get > real-time data for all of North America. I think the reason for measuring > it yourself is to see local power quality and things load switching inside > your own building, that's transients. > > > > The other way to measure AC with zero added equipment is to treat it as an > audio signal and after reducing it to 1 volt run it into an audio interface > And then use FFT. This will let you see very small spikes and noise. It > depends again on your purpose for doing this. > > > > > On Sat, Nov 16, 2013 at 1:18 AM, Magnus Danielson < > mag...@rubidium.dyndns.org> wrote: > >>> On 11/16/2013 09:52 AM, Chris Albertson wrote: >>> Your method tosses out a lot of data. You can't see transients. Ideally >>> rather then record a 1 second average you'd record the time of EVERY zero >>> crossing. It sounds like a lot of data but not really. You only record >>> 32 bits 60 times each second. That is 240 bytes per second. >> But you want it filtered to avoid the transients. Those are really not >> that interesting when you measure the grid. >> >> Also, if you use the event trigger method you probably want to use an >> amplifier to increase the slew-rate such that noise does not convert >> into time jitter. >> >> 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. > > > > -- > > Chris Albertson > Redondo Beach, California > ___ > 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] Mains frequency
The signal is 120 volts. You hardly need to amplify it. Clip it with a diode to +- 9 volts so as not to blow up your serial port. But I'd use a transformer for safety. The zero crossing detectors are built into the RS232 interface.You take advantage of the RS232 spec which has a DCD pin input of about +-9 volts that is already set up to find a leading edge of a pulse and cause a very low latency interrupt. The system software already will capture the time all inside a kernel level interrupt handler. The jitter turns out to be on the order of a single digit microseconds. Good enough for measuring a 60Hz signal. I guess if you want to see transients depends on the purpose of the experiment. Are you looking at local AC power quality or wanting to measure the grid. The grid is well monitored, just use FNET and you get real-time data for all of North America. I think the reason for measuring it yourself is to see local power quality and things load switching inside your own building, that's transients. The other way to measure AC with zero added equipment is to treat it as an audio signal and after reducing it to 1 volt run it into an audio interface And then use FFT. This will let you see very small spikes and noise. It depends again on your purpose for doing this. On Sat, Nov 16, 2013 at 1:18 AM, Magnus Danielson < mag...@rubidium.dyndns.org> wrote: > On 11/16/2013 09:52 AM, Chris Albertson wrote: > > Your method tosses out a lot of data. You can't see transients. Ideally > > rather then record a 1 second average you'd record the time of EVERY zero > > crossing. It sounds like a lot of data but not really. You only record > > 32 bits 60 times each second. That is 240 bytes per second. > But you want it filtered to avoid the transients. Those are really not > that interesting when you measure the grid. > > Also, if you use the event trigger method you probably want to use an > amplifier to increase the slew-rate such that noise does not convert > into time jitter. > > 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. > -- Chris Albertson Redondo Beach, California ___ 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] What happened tohttp://tf.nist.gov/timefreq/general/pdf ?
Stephan, Try again. It looks ok to me. Test with: http://tf.boulder.nist.gov/general/pdf/1.pdf You can also use the search page: http://tf.nist.gov/timefreq/general/publications.htm /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.
Re: [time-nuts] Mains frequency
Random noise always converts into time jitter. It doesn't matter how much you amplify the input signal, noise can push the detected zero crossing wherever it wants to. -Chuck Harris Magnus Danielson wrote: On 11/16/2013 09:52 AM, Chris Albertson wrote: Your method tosses out a lot of data. You can't see transients. Ideally rather then record a 1 second average you'd record the time of EVERY zero crossing. It sounds like a lot of data but not really. You only record 32 bits 60 times each second. That is 240 bytes per second. But you want it filtered to avoid the transients. Those are really not that interesting when you measure the grid. Also, if you use the event trigger method you probably want to use an amplifier to increase the slew-rate such that noise does not convert into time jitter. 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. ___ 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] What happened to http://tf.nist.gov/timefreq/general/pdf ?
Hi All, It seems that NIST changed the location of http://tf.nist.gov/timefreq/general/pdf. I hope they didn't remove it since it contained some of my favourite references. Does anyone know what the new location might be? Best, Stephan. ___ 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] Mains frequency
would probably be an interesting comparison. I am working with a guy on the eastern grid part now. You arent using python for processing on the pc are you? If so, I would be interested in your script. I am trying to verify I am not a just a little off with mine. Bill On Sat, Nov 16, 2013 at 1:55 AM, Kevin M. Rosenberg wrote: > Not on the eastern grid, but I had hook my picpet ac mains logger back to > the southwest grid if that would be of any help. > > On Nov 15, 2013, at 7:51 PM, Bill Dailey wrote: > > > I have my picpet faithfully measuring grid frequency and was wondering > if anyone else if the eastern grid has a live measure to compare to? > > > > 110vac-->5vac-->100ohm-->picpet event---> python average 60 cycles--> > log freq every second. > > > > Sent from mobile > > ___ > > 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. > -- Doc Bill Dailey KXØO ___ 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] Mains frequency
Here is a real-time map of mains frequency http://fnetpublic.utk.edu/gradientmap.html A common way to measure this is to connect a 9 volt AC plug-in power supply to the DCD pin of a serial port and let the PPS system log and time stamp each cycle. You can do it no more hardware than the transformer and any PC-like computer. The computer can bedding other tasks at the same time, like serving files or whatever. On Fri, Nov 15, 2013 at 6:51 PM, Bill Dailey wrote: > I have my picpet faithfully measuring grid frequency and was wondering if > anyone else if the eastern grid has a live measure to compare to? > > 110vac-->5vac-->100ohm-->picpet event---> python average 60 cycles--> log > freq every second. > > Sent from mobile > ___ > 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. > -- Chris Albertson Redondo Beach, California ___ 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] Mains frequency
rough comparison... I didnt have my interval right for this set. https://www.dropbox.com/s/1gi5tbf96yop5hz/stonercompare.JPG On Sat, Nov 16, 2013 at 3:02 AM, Bill Dailey wrote: > Understood.. I have it every 6 cycles now to sync up with his > synchrophaser. I wrote the script so I can specify the number of cycles I > average. Right now it is at 6 because his measures are every 0.1s. > > > On Sat, Nov 16, 2013 at 2:52 AM, Chris Albertson < > albertson.ch...@gmail.com> wrote: > >> Your method tosses out a lot of data. You can't see transients. Ideally >> rather then record a 1 second average you'd record the time of EVERY zero >> crossing. It sounds like a lot of data but not really. You only record >> 32 bits 60 times each second. That is 240 bytes per second. >> >> On Fri, Nov 15, 2013 at 6:51 PM, Bill Dailey wrote: >> >> > >> > 110vac-->5vac-->100ohm-->picpet event---> python average 60 cycles--> >> log >> > freq every second. >> >> >> -- >> >> Chris Albertson >> Redondo Beach, California >> ___ >> 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. >> > > > > -- > Doc > > Bill Dailey > KXØO > > > > > -- Doc Bill Dailey KXØO ___ 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] Mains frequency
On 11/16/2013 09:52 AM, Chris Albertson wrote: > Your method tosses out a lot of data. You can't see transients. Ideally > rather then record a 1 second average you'd record the time of EVERY zero > crossing. It sounds like a lot of data but not really. You only record > 32 bits 60 times each second. That is 240 bytes per second. But you want it filtered to avoid the transients. Those are really not that interesting when you measure the grid. Also, if you use the event trigger method you probably want to use an amplifier to increase the slew-rate such that noise does not convert into time jitter. 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] Mains frequency
Understood.. I have it every 6 cycles now to sync up with his synchrophaser. I wrote the script so I can specify the number of cycles I average. Right now it is at 6 because his measures are every 0.1s. On Sat, Nov 16, 2013 at 2:52 AM, Chris Albertson wrote: > Your method tosses out a lot of data. You can't see transients. Ideally > rather then record a 1 second average you'd record the time of EVERY zero > crossing. It sounds like a lot of data but not really. You only record > 32 bits 60 times each second. That is 240 bytes per second. > > On Fri, Nov 15, 2013 at 6:51 PM, Bill Dailey wrote: > > > > > 110vac-->5vac-->100ohm-->picpet event---> python average 60 cycles--> log > > freq every second. > > > -- > > Chris Albertson > Redondo Beach, California > ___ > 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. > -- Doc Bill Dailey KXØO ___ 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] Mains frequency
Your method tosses out a lot of data. You can't see transients. Ideally rather then record a 1 second average you'd record the time of EVERY zero crossing. It sounds like a lot of data but not really. You only record 32 bits 60 times each second. That is 240 bytes per second. On Fri, Nov 15, 2013 at 6:51 PM, Bill Dailey wrote: > > 110vac-->5vac-->100ohm-->picpet event---> python average 60 cycles--> log > freq every second. -- Chris Albertson Redondo Beach, California ___ 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] Mains frequency
On 11/16/2013 08:55 AM, Kevin M. Rosenberg wrote: > Not on the eastern grid, but I had hook my picpet ac mains logger back to the > southwest grid if that would be of any help. They are separated, so they are not phase coherent. Texas is it's own grid too. Cheers, Magnus > > On Nov 15, 2013, at 7:51 PM, Bill Dailey wrote: > >> I have my picpet faithfully measuring grid frequency and was wondering if >> anyone else if the eastern grid has a live measure to compare to? >> >> 110vac-->5vac-->100ohm-->picpet event---> python average 60 cycles--> log >> freq every second. >> >> Sent from mobile >> ___ >> 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] Mains frequency
Not on the eastern grid, but I had hook my picpet ac mains logger back to the southwest grid if that would be of any help. On Nov 15, 2013, at 7:51 PM, Bill Dailey wrote: > I have my picpet faithfully measuring grid frequency and was wondering if > anyone else if the eastern grid has a live measure to compare to? > > 110vac-->5vac-->100ohm-->picpet event---> python average 60 cycles--> log > freq every second. > > Sent from mobile > ___ > 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.
