Re: [time-nuts] More Allan deviation data
Hi Didier, you may use the DRIFT section of the graphic editor of PLOTTER to remove a phase drift due to a constant frequency offset as seen in this data, with the result that you get more visual resolution out of it, as in the attached PDF. 73 de Ulrich, DF6JB -Ursprüngliche Nachricht- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Didier Juges Gesendet: Sonntag, 29. Oktober 2006 06:32 An: !Time Nuts Betreff: [time-nuts] More Allan deviation data I moved the GPS antenna as high as I could in the shack (instead of on a shelf at eye level) and it seems to have significantly improved the signal. Here is the latest plot of the HP10811 against the GPS, unlocked. http://www.ko4bb.com/Test_Equipment/HP10811-GPS-10-29.png (sorry the screen shot is cropped at the bottom) and the data file is at http://www.ko4bb.com/Test_Equipment/HP10811-GPS-10-29.dat Didier KO4BB ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts Counter.pdf Description: Adobe PDF document ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] More Allan deviation data
I had to stack up frequency counters on top of frequency counters (to measure time difference and each input frequency simultaneously - 3 counters) and the last one on the top, a HP 5334B, was fairly high and just about level with the antenna, about 2 feet away. I found out that if I stood in line with the antenna and the counter, my shadow would significantly affect the cleanliness of the 1 PPS, so I moved the antenna just under the ceiling and the problem went away. Amazing! Didier Rob Kimberley wrote: Interesting to know what obstructions you cleared by moving it higher. May have been getting some multipath from something on the antenna's apparent horizon. Rob K ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] More Allan deviation data
Ulrich Bangert wrote: Hi Didier, you may use the DRIFT section of the graphic editor of PLOTTER to remove a phase drift due to a constant frequency offset as seen in this data, with the result that you get more visual resolution out of it, as in the attached PDF. 73 de Ulrich, DF6JB Ulrich, I ran the OCXO with the new antenna location overnight, except that the laptop went to sleep some time in the night, so I have lost several hours of data, which may explain the sudden slope change in the plot below (I need to save timestamps I guess). However, the remaining data is good I think. There was no sudden noise, and about 5 phase jumps due to the OCXO drifting during the observation period. I downloaded the latest version of Plotter (10-27) and it's all there. I was able to quickly remove the phase jumps when the OCXO drifted past the divided down period, and then remove the remaining slow drift. What a nice piece of software! (even the menu now has a *normal* File-Open :-) The latest plots are at the usual place: http://www.ko4bb.com/Test_Equipment/HP10811-GPS_10-29-2.png http://www.ko4bb.com/Test_Equipment/HP10811-GPS_10-29-2_Allan.png Now that the data collection method seems to be getting close, I wonder how I should use the data, and what it means. The Allan deviation seems to taper around e-10 at 1000 seconds, then it looks like it wants to keep getting lower. As a reminder, this is the HP10811 against the GPS receiver. I am not sure what I should expect? Didier PS: I am still planning to measure ambient temperature at the same time as I collect TI, via the GPIB, using a HP 3478A voltmeter and a thermistor. This way, I should be able to correlate frequency changes and temperature changes. I assume I can tell Plotter to ignore the temperature field or display it with its own scaling. Should I use a specific character as field delimiter? (such as a comma, or just spaces?) (In the short term, temperature data will be thermistor values, until I write the code to convert in degrees. ) Also, if I use time stamps, should I use field delimiter between the time stamp and the data? What is the time stamps are discontinuous (as if the laptop falls asleep again), will that mess up Plotter? ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] More Allan deviation data
Didier, (even the menu now has a *normal* File-Open :-) you take the credit for this! 73 de Ulrich, DF6JB -Ursprüngliche Nachricht- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Didier Juges Gesendet: Sonntag, 29. Oktober 2006 15:22 An: Discussion of precise time and frequency measurement Betreff: Re: [time-nuts] More Allan deviation data Ulrich Bangert wrote: Hi Didier, you may use the DRIFT section of the graphic editor of PLOTTER to remove a phase drift due to a constant frequency offset as seen in this data, with the result that you get more visual resolution out of it, as in the attached PDF. 73 de Ulrich, DF6JB Ulrich, I ran the OCXO with the new antenna location overnight, except that the laptop went to sleep some time in the night, so I have lost several hours of data, which may explain the sudden slope change in the plot below (I need to save timestamps I guess). However, the remaining data is good I think. There was no sudden noise, and about 5 phase jumps due to the OCXO drifting during the observation period. I downloaded the latest version of Plotter (10-27) and it's all there. I was able to quickly remove the phase jumps when the OCXO drifted past the divided down period, and then remove the remaining slow drift. What a nice piece of software! (even the menu now has a *normal* File-Open :-) The latest plots are at the usual place: http://www.ko4bb.com/Test_Equipment/HP10811- GPS_10-29-2.png http://www.ko4bb.com/Test_Equipment/HP10811-GPS_10-29-2_Allan.png Now that the data collection method seems to be getting close, I wonder how I should use the data, and what it means. The Allan deviation seems to taper around e-10 at 1000 seconds, then it looks like it wants to keep getting lower. As a reminder, this is the HP10811 against the GPS receiver. I am not sure what I should expect? Didier PS: I am still planning to measure ambient temperature at the same time as I collect TI, via the GPIB, using a HP 3478A voltmeter and a thermistor. This way, I should be able to correlate frequency changes and temperature changes. I assume I can tell Plotter to ignore the temperature field or display it with its own scaling. Should I use a specific character as field delimiter? (such as a comma, or just spaces?) (In the short term, temperature data will be thermistor values, until I write the code to convert in degrees. ) Also, if I use time stamps, should I use field delimiter between the time stamp and the data? What is the time stamps are discontinuous (as if the laptop falls asleep again), will that mess up Plotter? ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
[time-nuts] More Allan deviation data
I moved the GPS antenna as high as I could in the shack (instead of on a shelf at eye level) and it seems to have significantly improved the signal. Here is the latest plot of the HP10811 against the GPS, unlocked. http://www.ko4bb.com/Test_Equipment/HP10811-GPS-10-29.png (sorry the screen shot is cropped at the bottom) and the data file is at http://www.ko4bb.com/Test_Equipment/HP10811-GPS-10-29.dat Didier KO4BB ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
