ToolPythonIntermediate Filtering with scipy.signal: mains hum and noise out of an ECG _, h = signal.freqz_sos(sos_N, worN=f_check, fs=fs)w, h = signal.freqz_sos(sos_N, worN=4096, fs=fs)w, h = signal.freqz_sos(sos_f, worN=8192, fs=fs)w, h = signal.freqz_sos(signal.butter(4, 40 / fs, output="sos"), worN=8192, fs=fs)