FFT single-sided amplitude spectrum plot spike at 1Hz of accelerometer data
조회 수: 3 (최근 30일)
이전 댓글 표시
i m trying to plot the alpitude spectrum of Z-axis accelerometer with a sample frequency of ~50Hz and signal length 18429.
Fs=46.9350530441355
% t is the time vector in millisecond from 0 to 392648.965000002
L=length(y) % y is accelerometer data 18429 records
subplot(2,1,1)
plot(t,y)
title('Signal')
xlabel('time (milliseconds)')
NFFT = 2^nextpow2(L); % Next power of 2 from length of y
Y = fft(y,NFFT)/L;
f = Fs/2*linspace(0,1,NFFT/2+1);
subplot(2,1,2
% Plot single-sided amplitude spectrum.
plot(2*abs(Y(1:NFFT/2+1)))
title('Single-Sided Amplitude Spectrum of y(t)')
xlabel('Frequency (Hz)')
ylabel('|Y(f)|')
What i get on second plot it starts with x(1), y(18.46) and than fading. the data are from accelerometer atached to car windsheald.
댓글 수: 9
Dr. Seis
2012년 5월 3일
I would create a new question... others who are more familiar with running the Matlab function "spectrogram" and overlaying plots will be able to help you. You do not need to transfer your time data into the frequency domain before you use "spectrogram" - you will input your time data directly.
채택된 답변
Dr. Seis
2012년 5월 3일
As a general rule of thumb, I will remove any trend and/or mean from the data before I run it through FFT.
댓글 수: 0
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!