Hi everyone,
I have been trying to use Butterworth as a lowpass filter to limit the frequanies of my signal. I have provided the attached code in which two simple sine waves with 2Hz and 10Hz frequencies have been added. I have used low pass Butterworth filter with 4Hz as low cut of frequency. I expected to have the sine signal with frequency=2Hz (2<4<10) but the output of the filter (and also its FFT) is a very ugly!! and weird signal. Would anyone please help me to figure out where my mistake is and how to solve this problem?
Thank you,
Soran