[R-390] Best approach for SSB mod on R-390A

[2002tii]

Andy wrote (regarding synchronous detection):

>(2) The classy way to do it is put a computer and DSP in the loop where the
>oscillator is tuned with a D/A converter from the computer. The computer and
>DSP do digital spectral analysis and look at the signals all around, then
>decide what number (frequency) to stuff into the D/A, and consequently what
>the oscillator frequency should be. This can be made arbitrarily smart,
>although more often than not it is still pretty dumb. On some of the $$$
>receivers, this "digital detector" is pretty good, like the high-end R&S
>offerings these days. Not for the casual listener, of course. If you have
>enough DSP horsepower, you do it all digitally with no hardware PLL at all.
>Being a DSP-head, this is my preferred implementation, but it takes a lot of
>careful DSP programming to make it work well.

It's an intriguing notion, and I'd love to see a good DSP 
implementation.  I have no doubt that Andy knows lots more about DSP 
than I do.  Even with substantial DSP horsepower, I've never gotten 
decent results trying to implement synchronous detection in DSP, nor 
have I seen a decent commercial DSP implementation (though I have not 
seen an R&S DSP receiver).

Best regards,

Don