[time-nuts] UK standard frequencies - where?

David J Taylor david-taylor at blueyonder.co.uk
Thu Oct 13 01:18:15 EDT 2011

> 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!

David GM8ARV
SatSignal software - quality software written to your requirements
Web:  http://www.satsignal.eu
Email:  david-taylor at blueyonder.co.uk 

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