![]() # Normalized frequency argument for cheby1 ![]() The plot shows just the pass band, but you can change the arguments of the xlim and ylim functions to see more. Here's a complete script, followed by the plot that it generates. (If you increase the order to 6, then the gain at 2 Hz is approximately -103.) In particular, I get a gain of approximately -78 dB at 2 Hz. So it appears that the specification that you give, "Sampling frequency = 32Hz, Fcut=0.25Hz, Apass = 0.001dB, Astop = -100dB, Fstop = 2Hz, Order of the filter = 5", are not compatible with a Type I Chebyshev filter. transition band width, Astop, Fstop, etc) are determined. A 5th-order, 1dB-ripple Chebyshev lowpass filter is constructed from two non-identical 2nd-order sections and an output RC network. Once those three parameters are chosen, all the other characteristics # Cutoff frequency relative to the Nyquist In your case, you could write something like fs = 32 # Sample rate (Hz)įcut = 0.25 # Desired filter cutoff frequency (Hz) The third argument is wn, the cutoff frequency expressed as a fraction of the Nyquist frequency. They do not do a good job of preserving the shape of digital signals.
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