Hello Don, I do not have examples for SDR. Thank you.

Hi,
There is no specific relationship between carrier frequency Fc and the bit rate Rb. Usually Fc >> Rb. If Fc is integral multiple of Rb, we will have full cycles of carrier waveform contained in a given bit period (Tb). For example, Fc = 2*Rb, you will have two whole cycles of carrier signal contained inside the bit period Tb.

You can choose Fc = 10*Rb, then the simulation code has to process 10 cycles of signal for one bit of information transmitted, this consumes more memory and takes more time for executing the simulation (Typically in BER simulation, we will be processing minimum 10^5 to 10^6 bits for obtaining smooth BER curves).

Why the Fc carrier frequency is 2*Rb(2/Tb). Can it be set to 1/Tb or 10/Tb…Aren’t we wasting the symbols if we set Fc other than 1/Tb

Yes. Rb is the bit rate which is the number of bits transmitted per second. If Tb is the bit period, Rb = 1/Tb

I want to know why the BPSK is sometimes a NRZ signal multiplied by a carrier(sin’2piftime)) and sometimes its represented by a sequence of 1 and -1.

then is it Fc=2*Rc a condition we does respect usually ???? and why ?

you are welcome