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Altera_Forum's avatar
Altera_Forum
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16 years ago

FSK adding I&Q correctly in phase and amplitude

I've done an FSK decoder that already works very well but there is a request to enhance the sideband surpression. the transmitting part encodes its binary stream with fsk, where it sends out tw...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

I am used to do FSK by converting phase info in I/Q to frequency. Your approach seems new to me.

Anyway, it might be good idea to model in matlab: you can generate symbols, modulate with f0/f1 then upconvert (by multiplication) then downconvert as you said:

I = RFinput x sin wt

Q = RFinput x cos wt

apply filters as you wish and display spectrum.

attached is some of my cluttered code for FSK model(much of it commented out, I am not sure about its working status but it might help: