Frequency correction/fmt

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N3DT
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Joined: 2011/02/05 - 18:47
Frequency correction/fmt

I'll try to make this short, but it's complicated.

I have a VK3HZ X-ref board in my TS2000 http://www.vk3hz.net/XRef/XRef_Home.html which locks the master osc (MO) to a 10MHz GPDSO oscillator. This gives me precise frequency settings, but the problem is the DSP oscillator is offset by about 2Hz which gives me a constant ~+2Hz offset (USB). I'm trying to figure out how to get a valid frequency readout with reasonable accuracy (sub Hz).

The fmt.exe and fcal.exe do not seem to work in my W7 cmd.exe. I tried the 'fcal fcal.dat' and all I get is 'cannot open fcal.dat'. I'm running them in the command window from the C:\WSPR directory where it all resides, but perhaps because of the X-ref board, I don't need to do this, the fcal that is.

I also have a Moto service monitor locked to the same 10MHz GPSDO and using it as an oscillator, the measurements I get with the 'measure audio frequency' in the Advanced window are all 1502.01 below about 8MHz and above 8MHz I get 1502.11. I guess this means that my MO is not varying, at least above and below 8 MHz, but my DSP is offsetting the measured freq. I've heard that it's not possible to bring the DSP reference into compliance.

I've tried to use Spectrum Lab as a ref, but I pretty much get the same ~2Hz offset. Can someone direct me here and then also tell me what numbers I need to put in the 'A and B' values in WSPR to get correct frequency readouts, at least in WSPR?

Or perhaps someone has a better idea how to proceed?

Thanks.
Dave