define frequency of signal from fft output
2 ビュー (過去 30 日間)
古いコメントを表示
what is the relationship between the sampling frequency Fs and frequency of signal of FFT function in matlab? assUme that, we have a signal with spectrum as follow picture. with Fs= 44.1Khz, I know that X-axis is not the frequecy of signal, right? How to define the frequency of this signal with followed spectrum? for example, at the point X-axis = 10000, with Fs= 44.1Khz, how to define frequency of signal at that point?
0 件のコメント
採用された回答
その他の回答 (4 件)
Ngoc Lam
2014 年 9 月 30 日
編集済み: Ngoc Lam
2014 年 9 月 30 日
1 件のコメント
Rick Rosson
2014 年 9 月 30 日
The sampling rate in your code is
Fs = 500/(4*pi);
which is approximately 40 samples per second. By the Nyquist Sampling Theorem, the maximum frequency that you can represent without aliasing is Fs/2 or approx 20 Hertz. Your signal, however, contains components at 50 Hertz and 100 Hertz, which are well above the maximum.
Rick Rosson
2014 年 9 月 30 日
Please try:
Fs = 1000;
dt = 1/Fs;
N = 12000;
t = dt*(0:N-1)';
x = sin(100*pi*t) + 2*cos(200*pi*t);
X = fftshift(fft(x))/N;
dF = Fs/N;
f = -Fs/2:dF:Fs/2-dF;
plot(f,abs(X));
1 件のコメント
Syed Masoud Shah kakakhel
2017 年 3 月 23 日
編集済み: Syed Masoud Shah kakakhel
2017 年 3 月 23 日
kindly @Rick Rosson can u comment...variables like what is N?? kindly will be more helpful..m waiting for response
参考
カテゴリ
Help Center および File Exchange で Fourier Analysis and Filtering についてさらに検索
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!