I am using fdesign.decimator to design an equiripple filter with given specifications. I have recently upgraded from R2007b to R2010a. In R2007b, this code output a filter with 89 coefficients, but the same code in R2010a results in a filter with 127 taps. This is breaking compatibility for my downstream code as I am using the filter and the signal output from the filter as a reference to compare with my filter code written in assembly.
Compare the output generated by the following code in R2007a and R2010a:
Fpass = 3400; % Passband Frequency
Fstop = 4000; % Stopband Frequency
Apass = 0.01; % Passband Ripple (dB)
Astop = 80; % Stopband Attenuation (dB)
Fs = 16000; % Sampling Frequency
h = fdesign.decimator(2, 'Lowpass', 'fp,fst,ap,ast', Fpass, Fstop, ... Apass, Astop, Fs);Hd = design(h, 'equiripple', ... 'FilterStructure', 'firdecim', ... 'MinPhase', true, ... 'MinOrder', 'any', ... 'StopbandShape', 'flat');
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