I have a question about BFSK/M-FSK modulations in GNU Radio but in can be common problem :)
If I have a symbol 1 or 0 and it has got 64 samples (2 periods of sin/cos) and I want to modulate it with 2 different frequencies for example:
f1 = 175 KHz = 5,7 us
f2 = 225 KHz = 4,4 us
Problem is that 0 or 1 binary are same width - 64 samples but width for cos/sin periods are diferent and longer period will be cut for shorter symbol.
Do I need to generate two diferent symbols width for 0 or 1 ? what with bigger M-FSK?
No, you typically leave your symbol length alone. You're right, these symbols will then contain different amounts of periods, but that's typically not really a problem, because it doesn't matter for your demodulation.
There's some fine mathematical differences in the energy these symbols might have, but in a system where that matters, you simply can't chose arbitrary frequencies -- that's where OFDM comes into play.
You're right, however, this is just barely a GNU Radio question. Maybe you're better of on the ham radio stack exchange, or the DSP stack exchange site.