The problem with all of these comparative techniques is that you are
always dealing with relative error vs finite error. However the result
is usually well in excess of that needed for ham ops.
Yes, something like 100 Hz at 100MHz is good enough for my current needs,
but it's nice to be ahead of the game!
Another trick is to load one memory with a 1kHz RWM offset in USB and
another with a 1kHz offset in LSB so as to generate a tone for each
sideband. You then feed the AF into SpectrumLab and repeatedly toggle
between the two memories whilst adjusting the LO.
If you adjust the LO so that the difference between the LSB and USB
audio tone is at a minimum, that will give you the most accurate
setting. Any errors in the sound card will cancel out because you are
comparing the /difference /between the two 1kHz signals, any remaining
errors will be down to variables within the radio.
Hope that helps,
73 de David, G4IRQ
An excellent suggestion, David. At one point, I could get both the 10 MHz
and 15 MHz RWM signals, and switching between those showed less than a 1
Hz difference in the 1 KHz tone. Barely visible on the Spectrum Lab
display (covering about 1200 HZ total on a 1600 pixel wide display).
Having said all that, I've now ordered a low-cost GPSDO as it seems that
many of these off-air standards may not last too much longer!
73,
David GM8ARV
--
SatSignal software - quality software written to your requirements
Web: http://www.satsignal.eu
Email: [email protected]
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