[time-nuts] Frequency Measuring Test Results

[John Ackermann N8UR]

The results of the 2004 ARRL Frequency Measuring Test are out.  This 
year, they provided the nominal carrier frequency and asked for reports 
of the audio tone (in SSB, suppressed carrier mode).  That actually made 
the test less challenging because we were constrained by the accuracy of 
the announced carrier frequencies, which weren't given with the 
precision one might like -- they only announced to the nearest kHz, so 
our math had to start from that round number.

Here are the official frequencies and what I measured:


          ARRL                  N8UR
80M   1105.02Hz         1105.013Hz
40M   1108.26Hz         1108.279Hz
20M   1116.77Hz         ----

According to their averaging, that puts me +0.01Hz on 80, and -0.02Hz on 
40.  I'm surprised 40 came out that well given the horrible conditions 
on that band; we could barely hear the signal.  I heard nothing at all 
on 20M.

The same audio tone was used to feed all the transmitters, so you can 
see the frequency difference between them -- a 9.75Hz spread between the 
80M and 20M units.

Once again, I used a Linux spectrum analysis program (Baudline -- 
http://www.baudline.org) to measure the delta between the audio note of 
the unknown signal and the audio note of a local signal generator that 
was steered to within 50Hz or so of the unknown.  Baudline provides 
frequency resolution down to milliHertz, so is a good tool for this job.

I have a web page (not updated yet with the official results) that 
describes the setup and has a few screenshots at 
http://www.febo.com/time-freq/fmt/fmt2004.html

John