You might want to read this: http://tf.nist.gov/service/gpscal.htm
At 09:27 PM 3/24/2008, Marco A. Ferra wrote... >Dear time-nuts > >My name is Marco Ferra. I'm doing research on an electrical metrology >laboratory in Portugal, and I'm conducting a study on how to establish >tracebility to frequency using one (or more) GPSDO's. I came across >febo.com's site and this mailing list after searching the net. Let me >tell you what I'm doing. > >I have put side-by-side two GPS receivers, one HP58503 (now owned by >Symmetricom I believe) and a Fluke 910R, both with it's own antenna. >Both antennas are separated by about 100 meters. I'm tracking the 10 >MHz output of both GPS receivers with a Fluke PM6681R Counter. I'm >using the internal Rubidium oscillator of the counter and using >channels >A and B for the measurements. Each 10 seconds, I'm recording the >frequency on channel A, B, and the phase (in degrees) between the two >signals. I have resolution on the phase by 1/10th of degree. > >With the phase, I can get the time differente in nano-seconds between >the two signals: > >=phase(degress)/(360*10000000)*10^9 > >I'm putting 10000000 Hz has a nominal frequency for the calculation, >I'm >not sure if should use the frequency recorded on channel A or B. > >Then I calculate the time difference, the TIE (ns), the Delta Tie (ns) >accumulative, and then the Delta f (it's equal to Delta TIE (ACC) / >measurement time (could be 10, 20, 30 secs)). Please take a grasp at >page 4 of >http://www.pendulum-instruments.com/Assets/download/accurate_calibration >_article.pdf > >Given these two GPSDO's, and given the very small Delta f, I can >assume >that both GPSDO's are functioning proprely (could I indeed?). But I'm >not sure how I can get tracebility to national standards, to NIST, for >example, on the 10 MHz output frequency. Perhaps it's difficult, but >I >need a solid proof that my 10 MHz output is traceble to a primary >laboratory. > >I have seen that you all have a vast experience in this area, and >perhaps we could work together to gather good results and achive this >goal. > >Sincere regards, and thank you for reading, >Marco > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
