# Convolving with the frequency response of a filter

With scipy I can use signal.butter and signal.lfilter on a time signal. Performing a Fourier transform then shows me that the filter worked.

Using signal.freqz I can get the frequency response of the filter. Is there anything stopping me from simply taking the FT of my time signal and convolving it with my frequency response?

• Nothing stops you. BTW, if you convolving in frequency is like multiplying in time. – Juancho Jun 15 '17 at 14:17
• Note that multiplying two FFTs results in the same as a circular convolution in the time domain. So be prepared for the beginning and/or end of your "filtered" time domain signal block to look funny. – hotpaw2 Jun 16 '17 at 1:57