> Andy wrote: > > tell me more about the above. How does the switching of frequencies > generate tones heard at the other end. >
The transmitted FSK frequency is simply a CW signal that is shifting frequency at the symbol rate. Just like listening to a CW morse signal, it heterodynes to become a "tone" at the receiver. It is beating against the receiver's BFO (product detector) at the frequency difference between the SSB dial frequency and the FSK carrier frequency to create the audio tone at the receiver. When the receiver's reference (BFO) carrier frequency is tuned 1kHz from the FSK carrier frequency, a 1kHz audio tone is produced. Bonnie KQ6XA
