You cannot ignore the fresp function, that is where you specify the response you want (both magnitude and phase). If you are making a differentiator or a hilbert-transform filter, you can use the pre-written fresp functions "differentiator" or "hilbert", respectively. Otherwise, you'll have to write your own fresp function. Type "help cremez" for the details. If you are trying to design a minimum-phase FIR filter, you can do the following without using cremez: 1. Design a normal, linear-phase FIR filter using remez (not cremez). 2. The MATLAB statement "Flt_min = polystab(Flt)" converts the linear phase filter Flt into the minimum-phase filter Flt_min having the same magnitude response. If, however, the phase response you want is custom, such as you'd need for channel equalization, you'll have to write your own fresp function. Sincerely, Glen Ragan |