Hi
 I have a question about pulse shaping by the raised cosine filter.
 I select roll-off factor = 0.2. Fs/Fd=4 , delay= 9 , 10 , 11 , 12 , ...
 I increase the length of the filter . 
 Frequency response is better in results. 
 I write a vhdl code for it. I synthesis it in FPGA.
 I expect that frequency response is better. S/N  is better ,
 But is not. why?
 
thanks
"gharib"