How to show the time history of a signal down-sampled under the rates of 25Hz & 40Hz and find its DFT analysis using Matlab ? The sample signal is in a data file (sensor_data.mat) its sampling rate is 1000Hz.
I can get the time history and the DFT analysis of the signal.
Fs = 1000; % sampling rate T=1/Fs; % sample time L= 20000; % lenght of signal t=(0:L-1)*T; % time vector figure(1) plot(t,u) grid; title('Time History of the Signal') % dft analysis yf=fft(u); w=[0:2*pi/L:(L-1)*2*pi/L]; figure(2) plot(w/(2*pi*T),abs(yf)) grid title('DFT analysis of the signal sampled at 1000Hz')
But how do I down-sample it ? I know Matlab has a function for it (downsample), but I'm not getting any correct answers.
Also how do I find the signals frequency range and amplitude over its frequency range from the DFT analysis ?
Thanks in advance, Please help !!