About fx awgn()

I use awgn((x,snr,'measured') function in order to obtain a output with somelevel of noise, but I want to know how Matlab is measuring the power of x. Does anybody knows how?

Thanks.

Answer 1

[Wayne King]

Hi, if you use 'measured', the signal power is

    sigpower = norm(sig,2)^2/length(sig);

The L2 norm squared divided by the length of the signal.

If you are then using the POWERTYPE 'db', the power is

10*log10(sigpower)

Hope that helps

Answer 2

[J. M. Wincn]

The above answer is nice, concise, but incomplete, and anyone who would attempt to use it should do so with caution. The OP did not precisely specify what he was attempting to do, whether the target result was meant to represent Eb/N0 or Es/N0, Binary or M-ary coding, and whether he intended to simulate one sample per bit time or N samples per bit time. Depending on presumed conditions, you could get dramatically different results with the same calculation method.