[GreenKeys] FSK vs. AFSK

[WA5CAB@cs.com]

Group,

AFSK is DSB AM with full carrier (actually I guess it could be so-called 
compatible AM if you fed the AFSK generator audio into one channel of an SSB 
transmitter in AM mode, but that has some of it's own disadvantages).  No BFO is 
used at the receiving end, only audio type converters will work at the receiving 
end, and frequency stability of the transmitter and receiver are of shall we 
say lesser importance.  Which is why it was used at VHF to begin with.

Regardless of how it is generated, FSK outputs two discrete frequencies 
(except when the frequency is shifting) rather than the five of AFSK (plus their 
Bessel Function components in both cases).  Frequency stability is important at 
both ends.  At the receiving end it is not possible (at least in the ideal 
case of infinite carrier supression) to tell how the signal was generated.  
Either IF or audio converters can be used.

Did I miss any weasel words?

73
Robert Downs - Houston
<http://www.wa5cab.com> (Web Store)
<wa5cab@cs.com> (Primary email)
<wa5cab@houston.rr.com> (Backup email)


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