Accurate Frequency Measurements

Do you enjoy making very precise measurements? Have you always wanted to enter the ARRL Frequency Measurement Test (FMT), but held back because you assumed that expensive laboratory equipment must be required?

Appendix C of the WSPR 2.0 User's Guide, ,
explains how to calibrate your WSPR transceiver to an accuracy better than one Hertz using over-the-air standard-frequency signals. Many WSPR users have used this procedure to establish calibration constants for their own radios, resulting in significantly improved frequency accuracies of reported WSPR spots.

About six months ago, I wrote some simple software tools that largely automate the procedure described in Appendix C and extend it to enable measuring the frequencies of unknown test signals. I used it for the ARRL FMT held last April, and my resulting measurements of all seven FMT test signals were within less than 0.3 Hz of the published "true" frequencies. (See for results of the April 2010 FMT.) My equipment was very simple: nothing more than my normal WSPR setup, a Kenwood TS-2000 with the software mentioned above. Any CAT-controllable radio would do. I've even tested it with my SoftRock, with excellent results.

The next ARRL Frequency Measuring Test is less than three weeks away: November 11, 2010, starting at 0230 UTC (the evening of Nov 10 in US time zones). Details are in November QST and on the ARRL web site at .

If there is significant interest from others who would like to try entering the November 2010 FMT, I'd be happy to write some brief instructions on using the new frequency-measuring software tools, and make them available for free download. It will probably be simplest to just include everything in a packaged release of WSPR 2.1. If you are interested, please let me know (k1jt at arrl dot net).

-- 73, Joe, K1JT