[GreenKeys] FSK converter madness

[Harold Hallikainen]

Interesting and complex design. I have not analyzed the loop interface, so
I can't comment on the 10 mA space. The tone generator is interesting. It
reminds me of a HAL design, though the HAL design used crystals for each
generated frequency while this uses a PLL synthesizer. The DAC for the
tone generation is very similar to what I've seen in HAL designs.

On the demodulator side, the design is similar to Dovetron units. That is,
the use of identical filters for mark and space and doing frequency
conversion in front of the filters.

Interesting design, but complicated. It's sure a whole lot easier to do in
DSP!

Thanks for posting the manual. I'll study it some more.

Harold
https://w6iwi.org



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