The code below creates a frequency-flat Rayleigh fading channel object and uses it to process a DBPSK signal consisting of a single vector. Notice that the example uses filter before awgn this is the recommended sequence to use when you combine fading with AWGN -The code below creates a frequency-flat Rayleigh fading channel object and uses it to process a DBPSK signal consisting of a single vector. Notice that the example uses filter before awgn　this is the recommended sequence to use when you combine fading with AWGN