- ifftshift
- fft
Time-shift after fft & filter?
조회 수: 3 (최근 30일)
이전 댓글 표시
I tried to implement a simple LP filter on an audio file, but I'm slightly confused by the apparent shifting of the signal in the time domain. What have I overlooked / misunderstood? Thanks.
filename = 'Raw_Wav_20180425_000226.wav';
[y,fs] = audioread(filename);
subplot(1,2,1)
plot(t,y)
xlabel('Time (s)')
ylabel('Amplitude')
title('Raw')
fmax1 = 40; %end of pass band
fmax2 = 60; %end of transition band
nt = length(y);
t = [0:nt-1]/fs;
y = y-mean(y);
dF = fs/nt;
f = -fs/2:dF:fs/2-dF;
yft = fftshift(fft(y));
I = find(abs(f)>fmax2);
yft(I) = 0;
I = find( abs(f)>fmax1 & abs(f)<=fmax2 );
yft(I) = yft(I) .* hanning(length(I));
y = ifftshift(ifft(yft));
subplot(1,2,2)
plot(t,y)
xlabel('Time (s)')
ylabel('Amplitude')
title('Post-filter')
댓글 수: 0
채택된 답변
Sugar Daddy
2020년 6월 12일
As you have taken fft first and then fftshift, so if you want to do inverse of this, you need inverse of fftshift first as it is performed at the end. so the order of inverse must be
추가 답변 (0개)
참고 항목
카테고리
Help Center 및 File Exchange에서 Spectral Measurements에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!