Download the data file from the assignment $$In computer$-$lab test $2$: signal processing$$ on Canvas. The file you need is named $\_\_$q$2.$mat, where and are the day and start time of your laboratory class.

$2.$ Put this file in your MATLAB working folder.

$3.$ Load this file and extract a time array t and a signal array y with the following code

data $=$ load$("$filename$")$;

replacing filename with the name of the file you downloaded.

$4.$ Then

$($a$)$ Use MATLAB to calculate the sampling frequency of these data and save it in a variable fs $($hint: use the values in the time array t$)$

$($b$)$ Use MATLAB to calculate the Nyquist frequency and save it in a variable fn

$($c$)$ Plot the spectrum over the frequency range $0<=$ f $<=$ fn$.$

$($d$)$ There should be three frequency spikes in this spectrum. The highest of these is present due to aliasing. What is the true frequency that has been aliased? Save this true frequency value in a variable called ftrue.