How many amplitude/phase/frequency values do you need for the ASK/PSK/FSK modulation? If it's just two then the circuit can be simple. More than two will need a more complex circuit.
Are you looking for a modulator circuit or a demodulator?
How many amplitude/phase/frequency values do you need for the ASK/PSK/FSK modulation? If it's just two then the circuit can be simple. More than two will need a more complex circuit.
Are you looking for a modulator circuit or a demodulator?
Okay. So what is the source of the modulating signal? A micro? A Push-button? .....?
What will your demodulator do? Light a LED? Beep? .....?
What is the transmission medium between modulator and demodulator?