Hi, Ed. Here's a group that I belong to: http://groups.yahoo.com/group/FMT-nuts/
Many of the members there are true time/freq measuring nuts. The Midwest VHF/UHF society run their own FMTs at different times of the year. You can also Google time-nuts. If you don't mind a simplistic overview, the audio output of the radio is sent to the sound card of the PC. One uses an audio analysis program like Spectrum Lab or Spectran to analyze the frequency of a beat note. Sometimes that is just watching the carrier of WWV while in CW mode, sometimes a very accurate signal generator is also input to the RX at the same time as the signal under test, and the difference measured. Doing the FMT can be a great challenge and a lot of fun. However, getting really good at it can take some work (which is part of the fun). Often times, ones measurements are limited by the Doppler shift of the ionosphere (yes, there is Doppler even at HF). In the finally analysis, one sometimes has to resort to "guessiplication" for deciding what frequency to submit as your measurement. All that said, on one of the FMTs done a year or so ago, I was able to get within 9 milliHertz of actual carrier frequency on a 20M test out of the Midwest. I used an HPSDR Mercury DDC receiver that was phase locked to a Trimble Thunderbolt GPSDO. That's about 6 parts per ten trillion. And I wasn't even the closest... 73, Bruce N1RX > Might be a great way to demonstrate the new accuracy of the K3EXREF! > http://www.arrl.org/frequency-measuring-test > Any tips on how one measures the frequency in these tests? > 73, Ed - KL7UW, WD2XSH/45 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
