i want to simulate a system that uses ask,fsk ,psk in Matlab with additive Gaussian noise for each mode . figure shows the system propti and Eb/N0=6db my question is how to calculate the standard variation of the Gaussian noise for each mode , i tried the following :

• EbN0dB=6;

• EbN0=10^(EbN0dB/10);% db to linear scale

• EN0=1/(EbN0);