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WSJT without upconversion


Andy G4JNT
 

It looks like WSJT-X is never going to offer a digital output version of the tones.  So to counter that I wrote a bit of pic code that measures the instantaneous frequency, ie. actually measures the tone period.   That gives a near-instant response to tone changes so ought, theoretically, to cope with the fast modes as well

At the moment all I do is decode the tone into a tone-No. count and display this on LEDs connected directly to pic O/P lines. This prog was only a demonstrator, but a simple D/A made up just from resistors acting on a 10MHz reference will allow direct generation wihtout having to upconvert from PC audio.   One idea I'll be investigatoing, put the reconstituted step voltage waveform into an integrator (op-amp type) and use to PHASE modulate a 10MHz source.

Take a look at this video of it reconstituting the 9 tones from a JT9H waveform.   Other (wide shift) modes can be coped with by changing a few variables and a small look-up table in the PIC.


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