2011 ARRL Frequency Measurement Test

The object of the test was to measure as closely as you can the exact transmit frequency of four stations on both coasts in a time span of about 45 minutes. There were seven measurements in all. Conditions were not good. The west coast stations were weak and the signals had a lot of doppler which made exact frequency measurement a matter of chance ( or expertise I didn't have! ). My accuracy goal was to get within 100 millihertz (0.10 Hz). I met that on two. I was within 1.0 Hz on all seven which was good enough for the "green line" in the ARRL data report.

My results

Station Transmitted Measured Difference Err ppx
K5CM 3575607.73 Hz 3575607.63 Hz - 0.10 Hz 2.83E-08
7054511.27 Hz 7054511.01 Hz - 0.26 Hz 3.69E-08
W8KSE 3575648.60 Hz 3575648.77 Hz + 0.17 Hz 4.75E-08
7054551.30 Hz 7054550.73 Hz - 0.57 Hz 8.08E-08
W6OQI 3575695.66 Hz 3575695.74 Hz + 0.08 Hz 2.28E-08
7054586.57 Hz 7054585.80 Hz - 0.77 Hz 1.09E-07
WA6ZTY 7054576.72 Hz 7054576.04 Hz - 0.68 Hz 9.64E-08
Average 6.02E-08

Link to full results

Here is the link to the ARRL web site with the full results: http://www.b4h.net/fmt/fmtresults201104.php

Equipment Used

Icom IC-756pro3 Receiver
SignaLink USB external "soundcard"
Trimble Thunderbolt GPSDXO
Sectrum Lab 2.7 signal processing software


WWVB at 60kHz
Thunderbolt at 10mHz


A XLS sheet that shows the data reduction for one of the tests (W8KSE 40 meters) IS HERE

Click cells D3 D4 D7 and F7 to see the formulas used to calculate the unknown frequency.