How is the frequency of the signals transmitted reflected on the modulation scheme (eg: FSK, ASK)? Say if I want to transmit a sequence of signal with a frequency of 20kHz(an amplitude of 7V is 1, no amplitude is 0), is there any requirement of the FSK or ASK I'm using? How should I choose the modem accordingly? What are the parameters I should look at? Thanks :D
Stephanie