hi everyone!! i designed a fir filter with the Xinlinx ipcore two days ago. and i am facing a problem! in my design, i have two signal multiplied, one is sin(2*Pi*240k*t) and the other one is
-sin(2*Pi*240k*t+F).so it is obvious that the result has a signal of
480K,which is undesired in my system. and this is what the filter for! the system clk of the filter is 48M and the sample rate is 4.8M! the problem i met is that the output of the filter has a freqency of 4.8M.i know it may have some relation to the sample rate,cause there is no more 4.8M clks! in additon ,i simulated the model in Matlab and the result turned out to be perfect!i got the coefficients of the filter from the simulation. could anyone help me? any comments would be appreciated! thanks