I need to solve the problem with BER calculation. I made a coherent correlation type detector in MATLAB for a BPSK signal, but when I demodulate the noised signal BER is much worse than it sould be in theory for coherent detection. I add noise using awgn() function setting the desired SNR[dB]. I assume Eb/No[dB]=SNR[dB]+10log(Tbit/Tsample) So why is it? My M-Files are attached. I used 1000 bits to simulate and SNR=-12dB which equals according to the Equation Eb/No=8dB. Theoretically the result shoul have been around 1e-4 and I get BER=4e-2. The BER curves of the desired and of the Reality I have are also enclosed. Please help!