0.4 Lab 2 : prelab part ii (upsampling and downsampling)

Upsampling and downsampling in Matlab can be implemented by the functions downsample and upsample . Design a lowpass filter of length 100 and cut off frequency of $\frac{\pi }{3}$ (you can use the Matlab function fir1 ). To visualize the effect of downsampling and upsampling , you might want to plot different magnitude responses in one figure.The Matlab syntax: [h,w] = freqz(hfilt) returns the frequency response of the filter hfilt without logarithmic scaling (see Matlab help documentation for more information).

Plot the frequency response of your newly designed filter together with its downsampled and upsampled versions by 2 in one figure. Redo the problem with the upsampling and downsampling factors equal to 3. Do your results agree with the theory?