Initialization of a demodulator object.
demod = demod_init(name,fs,fi,fsymb) demod = demod_init(wf,fs,fi,fsymb)
classical waveform name ('bpsk', 'qpsk', 'qam16', ...)
Waveform object (created with wf_init)
Input sample frequency
Intermediate (or RF) frequency
Symbol frequency