Re: [time-nuts] Time interval measurement vs dual mixer method
Hello to the group, Thanks for interesting discussion. I found a nice plot in"Measurement, Instrumentation, and Sensors Handbook, Second Edition", ( John G. Webster,Halit Eren), at 42-24 page. It shows that in short term stability (tau 1 - 10 s) dual mixer method is most sensible, in long term stability TIE and DM results are similar. I'm going to do the same mesurements with Rb standard (Pendulum 6689) as DUT. Data is now collecting. SD ___ 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] Time interval measurement vs dual mixer method
Hi What level of stability are you trying to measure? What sort of offset frequency are you running? What kind (phase noise / spurs / adev) offset oscillator are you using? What sort of limiter are you running with what sort of pre filtering? We have run around on a lot of generalities. You may have some issues that are specific to your setup. There is no “one size fits all” approach here. If you are running a couple of oscillators it the THz region and trying to look at ADEV from 1us to two months tau with one setup, a lot of what we have been saying simply does not apply. Bob > On Jan 21, 2018, at 4:23 AM, tim...@timeok.it wrote: > > > Corby, > thanks for the information. > > I'm definitely interested in the short therm ADEV but especially for Tau > from 1 day and over to test high stability standard over the time. > I will have further tests. > Cheers, > Luciano > > > Da "time-nuts" time-nuts-boun...@febo.com > A time-nuts@febo.com > Cc > Data Sat, 20 Jan 2018 16:14:10 -0800 > Oggetto [time-nuts] Time interval measurement vs dual mixer method > Luciano, > > I don't know of a commercial version. > > As you have seen as the two signals move away from close phase > coincidence the system noise level will increase. > > This is because the common offset oscillator noise will only cancel when > the phases are closely matching. > > This is mainly important for the lower Tau (like 1 to 10 seconds). > > I will normally adjust the phase of my reference or DUT so that myTIC is > reading 0.0XX (close to phase match) and very slowly rising. (with my > setup most DUT will age downward). > > Then I start logging the data. > > A typical run with a 1 week aged quartz will show the TIC count slowly > increase (and may wrap) and then as the aging continues the count will > reverse and eventually go "below" zero and wrap. > > A phase plot will show a nice parabolic looking curve going up and then > as the aging crosses it will curve down. > > If there are wraps the plotter program can take them out. > > Any long plot of Quartz WILL wrap! > > Now if you plot the AD you will see a normal type plot for a good Quartz. > > If the TIC count increased well past coincidence only the Higher Taus > will be accurate. > > For the lower Tau you need to cut off the data past where it climbed too > high. > > I typically will setup as described and run a short log of say 5 minutes. > > I might only keep the first 100 Seconds and plot the AD against that. > > This will give you an accurate plot for the lower Tau. > > These two plots can then be combined to give you the whole range. > > The attached plot of an FE405B illustrates this. > > The Red plot is against a very good FTS 1200 (2X10-13th at 1 thru just > past 10 Sec) > > The blue continuation is against a very good HP 5065A (1.5X10-13th at 100 > Sec) > > So if the lower Tau are important only use logged data that are in near > phase match! > > Hope this helps! > > Cheers, > > Corby > ___ > 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] Time interval measurement vs dual mixer method
Corby, thanks for the information. I'm definitely interested in the short therm ADEV but especially for Tau from 1 day and over to test high stability standard over the time. I will have further tests. Cheers, Luciano Da "time-nuts" time-nuts-boun...@febo.com A time-nuts@febo.com Cc Data Sat, 20 Jan 2018 16:14:10 -0800 Oggetto [time-nuts] Time interval measurement vs dual mixer method Luciano, I don't know of a commercial version. As you have seen as the two signals move away from close phase coincidence the system noise level will increase. This is because the common offset oscillator noise will only cancel when the phases are closely matching. This is mainly important for the lower Tau (like 1 to 10 seconds). I will normally adjust the phase of my reference or DUT so that myTIC is reading 0.0XX (close to phase match) and very slowly rising. (with my setup most DUT will age downward). Then I start logging the data. A typical run with a 1 week aged quartz will show the TIC count slowly increase (and may wrap) and then as the aging continues the count will reverse and eventually go "below" zero and wrap. A phase plot will show a nice parabolic looking curve going up and then as the aging crosses it will curve down. If there are wraps the plotter program can take them out. Any long plot of Quartz WILL wrap! Now if you plot the AD you will see a normal type plot for a good Quartz. If the TIC count increased well past coincidence only the Higher Taus will be accurate. For the lower Tau you need to cut off the data past where it climbed too high. I typically will setup as described and run a short log of say 5 minutes. I might only keep the first 100 Seconds and plot the AD against that. This will give you an accurate plot for the lower Tau. These two plots can then be combined to give you the whole range. The attached plot of an FE405B illustrates this. The Red plot is against a very good FTS 1200 (2X10-13th at 1 thru just past 10 Sec) The blue continuation is against a very good HP 5065A (1.5X10-13th at 100 Sec) So if the lower Tau are important only use logged data that are in near phase match! Hope this helps! Cheers, Corby ___ 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] Time interval measurement vs dual mixer method
Luciano, I don't know of a commercial version. As you have seen as the two signals move away from close phase coincidence the system noise level will increase. This is because the common offset oscillator noise will only cancel when the phases are closely matching. This is mainly important for the lower Tau (like 1 to 10 seconds). I will normally adjust the phase of my reference or DUT so that myTIC is reading 0.0XX (close to phase match) and very slowly rising. (with my setup most DUT will age downward). Then I start logging the data. A typical run with a 1 week aged quartz will show the TIC count slowly increase (and may wrap) and then as the aging continues the count will reverse and eventually go "below" zero and wrap. A phase plot will show a nice parabolic looking curve going up and then as the aging crosses it will curve down. If there are wraps the plotter program can take them out. Any long plot of Quartz WILL wrap! Now if you plot the AD you will see a normal type plot for a good Quartz. If the TIC count increased well past coincidence only the Higher Taus will be accurate. For the lower Tau you need to cut off the data past where it climbed too high. I typically will setup as described and run a short log of say 5 minutes. I might only keep the first 100 Seconds and plot the AD against that. This will give you an accurate plot for the lower Tau. These two plots can then be combined to give you the whole range. The attached plot of an FE405B illustrates this. The Red plot is against a very good FTS 1200 (2X10-13th at 1 thru just past 10 Sec) The blue continuation is against a very good HP 5065A (1.5X10-13th at 100 Sec) So if the lower Tau are important only use logged data that are in near phase match! Hope this helps! Cheers, Corby___ 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] Time interval measurement vs dual mixer method
Hi The quality of the offset signal source matters in a DMTD system. If you are using a “noisy” source you will have trouble with the data. You also will have trouble if the offset signal is correlated in some way to one of the DUT signals. Bob > On Jan 20, 2018, at 3:43 AM, tim...@timeok.it wrote: > > > Hi Corby, > I did several tests to verify the system noise floor using the same source > for both input channels. I have seen that the result varies a lot as the > difference in time between the two channels varies. > Moreover, if I do two successive tests without changing the parameters and > the duts, the result can not be superimposed. > It may be that I make a mistake or do not take any parameter into account. > I also wonder if there is any commercial realization of the DMTD system. > Cheers, > Luciano > > > Da "time-nuts" time-nuts-boun...@febo.com > A time-nuts@febo.com > Cc > Data Thu, 18 Jan 2018 11:13:54 -0800 > Oggetto [time-nuts] Time interval measurement vs dual mixer method > Luciano, > > Not sure what you mean by "two measures made on the same DUT never > coincide". > > The plotter program takes out wraps which since your phase gain is so > large are due to happen. > > For lower Tau measurements just adjust the phase for close to equal and > run shorter plots. > > These can be spliced into the longer Tau plot. > > I routinely get repeatable plots on the same DUT with my DMTD setup. > > Careful setup and understanding what you can and cannot accomplish is the > key. > > Cheers, > > Corby > ___ > 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] Time interval measurement vs dual mixer method
Hi Corby, I did several tests to verify the system noise floor using the same source for both input channels. I have seen that the result varies a lot as the difference in time between the two channels varies. Moreover, if I do two successive tests without changing the parameters and the duts, the result can not be superimposed. It may be that I make a mistake or do not take any parameter into account. I also wonder if there is any commercial realization of the DMTD system. Cheers, Luciano Da "time-nuts" time-nuts-boun...@febo.com A time-nuts@febo.com Cc Data Thu, 18 Jan 2018 11:13:54 -0800 Oggetto [time-nuts] Time interval measurement vs dual mixer method Luciano, Not sure what you mean by "two measures made on the same DUT never coincide". The plotter program takes out wraps which since your phase gain is so large are due to happen. For lower Tau measurements just adjust the phase for close to equal and run shorter plots. These can be spliced into the longer Tau plot. I routinely get repeatable plots on the same DUT with my DMTD setup. Careful setup and understanding what you can and cannot accomplish is the key. Cheers, Corby ___ 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] Time interval measurement vs dual mixer method
Luciano, Not sure what you mean by "two measures made on the same DUT never coincide". The plotter program takes out wraps which since your phase gain is so large are due to happen. For lower Tau measurements just adjust the phase for close to equal and run shorter plots. These can be spliced into the longer Tau plot. I routinely get repeatable plots on the same DUT with my DMTD setup. Careful setup and understanding what you can and cannot accomplish is the key. Cheers, Corby ___ 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] Time interval measurement vs dual mixer method
Hi If the time offset gets to the point that it bothers the measurement, you likely are running to low a difference frequency. It is quite possible (though not easy) to get low parts in 10^-13 running an offset of 8 or 9 Hz at 10 MHz. If you are running very precise signals, then line stretchers can be used to get everything so it hits at the same point. There are NBS papers where they talk about doing exactly this sort of thing. Results were “within a couple of microseconds” as I recall. Bob > On Jan 17, 2018, at 1:44 AM, tim...@timeok.it wrote: > > > Hi Slawek, > I have tried two versions of DMTD and I think the biggest problem with this > method is the fact that two measures made on the same DUT never coincide. > The DMTD suffers from time wrap and the measurement results are linked to > the time difference presetted by t1 and t2. > At the moment I am using the TICC with good results, attached to the noise > floor. > I think that in order to have a better resolution we need to focus on a > recent production > error multiplier such as the A7 of Quartzlock or a similar one to be > self-constructing. > http://quartzlock.com/userfiles/downloads/manuals/A7-A_&_A7-MX_Manual.pdf > Luciano > www.timeok.it > > > Da "time-nuts" time-nuts-boun...@febo.com > A "time-nuts" time-nuts@febo.com > Cc > Data Tue, 16 Jan 2018 17:58:18 +0100 > Oggetto [time-nuts] Time interval measurement vs dual mixer method > > Hello to the group! > > Have you ever measured frequency standard (or other precision oscillator) > simultanously by time interval method (difference between 1 pps ref and 1 pps > DUT) and dual mixer method (e.q. with phase/frequency comparator)? I'm very > interested in results. > > Slawek > > > > > > ___ > 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] Time interval measurement vs dual mixer method
I am working to build a small DMTD system based on Bill Riley’s paper. Bill was kind enough to send me a package with updates. In the meantime, I tested an AD8302 phase detector coupled to an HP voltmeter (HP3456 and HP3457), both with the filter set. I believe the HP3456A voltmeter filter limits voltage changes to below 60hz. The results were interesting but I don’t have anything to compare them with though they did look correct from a relative standpoint. For instance, my Cs beam looked better than one Rb unit and my GPSDOs looked better at longer Tau. My HP 10811 looked correct when compared to others. The issue with the AD8302 though is that phase deltas below 3 degrees are inaccurate, actually the plots had flats at those phase deltas. Also, since it reports in degrees, you need to change that back to time which I did in a spreadsheet. Regards, Jerry Jerry Hancock je...@hanler.com (415) 215-3779 > On Jan 16, 2018, at 8:58 AM, slawek dabrowski wrote: > > > Hello to the group! > > Have you ever measured frequency standard (or other precision oscillator) > simultanously by time interval method (difference between 1 pps ref and 1 pps > DUT) and dual mixer method (e.q. with phase/frequency comparator)? I'm very > interested in results. > > Slawek > > > > > > > ___ > 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] Time interval measurement vs dual mixer method
Hi You have to measure two different outputs to do what you describe. The PPS measurements are limited to > 1 x10^-10 with most counters at tau = 1 second and 2x10^-11 with some exotic models. The mixer based stuff can get around three orders of magnitude past that at the same tau. Since a practical mixer system involves filtering one would expect some impact from that. The gotcha is the low resolution of the counter approach. You run out of resolution before you can really see anything. All that said, yes, I have measured the same device both ways and the results do agree within the accuracy constraints imposed by the techniques. Bob > On Jan 16, 2018, at 11:58 AM, slawek dabrowski wrote: > > > Hello to the group! > > Have you ever measured frequency standard (or other precision oscillator) > simultanously by time interval method (difference between 1 pps ref and 1 pps > DUT) and dual mixer method (e.q. with phase/frequency comparator)? I'm very > interested in results. > > Slawek > > > > > > > ___ > 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] Time interval measurement vs dual mixer method
Hello to the group! Have you ever measured frequency standard (or other precision oscillator) simultanously by time interval method (difference between 1 pps ref and 1 pps DUT) and dual mixer method (e.q. with phase/frequency comparator)? I'm very interested in results. Slawek ___ 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.
