I'm analysing some accelerometer data. The accelerometer was placed on a mechanical shaker and on this shaker a frequency sweep was performed.
When I look at the amplitudes of single sine waves they see to fit in the time and frequency domain. However, if I perform a sweep, the amplitudes are wrong.
The accelerometer data should be scaled right, I think it has to be some MATLAB
fft specific stuff. The following code was used to perform the FFT:
nfft= length(signalToAnalyse); %generate the freqvec halfn = floor(nfft / 2)+1; deltaf = 1 / ( nfft / Fs); freq = (0:(halfn-1)) * deltaf; % perform FFT fftRawResult = fft(signalToAnalyse,nfft); % convert from 2 sided spectrum to 1 sided magnitude(1) = abs(fftRawResult (1)) ./ (nfft); magnitude(2:(halfn-1)) = abs(fftRawResult (2:(halfn-1))) ./ (nfft / 2); magnitude(halfn) = abs(fftRawResult (halfn)) ./ (nfft);
Anybode some Ideas?
Below is the signal in time domain and frequency domain.