I am trying to simulate a distributed sensing system and I need to filter only frequencies lesser than 500 Hz(low pass filter) from acquired signal with sample rate 1250000 Samples/sec using below mentioned program:
%Time specifications: Fs = 1250000; % samples per second dt = 1/Fs; % seconds per sample StopTime = 0.25; % seconds t = (dt:dt:StopTime-dt); % seconds %Input Sine wave: Fc = 300; % hertz dataIn = cos(2*pi*Fc*t); % Plot the signal versus time: figure; plot(t,dataIn); xlabel('time (in seconds)'); title('Input signal'); zoom xon; wc=500; % cut off frequency Wn=wc/(Fs/2); % normalized frequency [b,a] = butter(6,Wn,'low'); figure; freqz(b,a) %Plot filtered output dataOut = filter(b,a,dataIn); figure; plot(t,dataOut) title('dataout') zoom xon;
However I am unable to filter the desired frequencies below 500 Hz, as the cut off frequency is dependant on the sampling rate. Kindly suggest what to be done as I am new in MATLAB.
Thanks in advance.