daqdocfft.m

简单的信号处理

function [f,mag] = daqdocfft(data,Fs,blocksize)
%    [F,MAG]=DAQDOCFFT(X,FS,BLOCKSIZE) calculates the FFT of X
%    using sampling frequency FS and the SamplesPerTrigger
%    provided in BLOCKSIZE

xfft = abs(fft(data));

% Avoid taking the log of 0.
index = find(xfft == 0);
xfft(index) = 1e-17;

mag = 20*log10(xfft);
mag = mag(1:floor(blocksize/2));
f = (0:length(mag)-1)*Fs/blocksize;
f = f(:);

plot(f,mag)
grid on 
ylabel('Magnitude (dB)')
xlabel('Frequency (Hz)')
title('Frequency Components of Tuning Fork')