MATLAB: Matlab coding for downsampli​ng……..​……

Question

How to downsample a sinusodial signal in matlab coding……………

Answer 1

If you have the Signal Processing Toolbox, you can use downsample() to simply downsample without lowpass filtering. Or use decimate() or resample() to first lowpass filter and then downsample.

 n = 0:159;
 x = cos(pi/4*n);
 % downsample by 2 starting with the first value
 y = downsample(x,2,0);
 % downsample by 2 starting with the second value
 y1 = downsample(x,2,1);

You can of course do the above with simple MATLAB commands:

 y = x(1:2:end);
 y1 = x(2:2:end);

In general, do consider either decimate()or resample() as these afford anti-aliasing through filtering.