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This problem is on the time sampling. Assume ideal impulse sampling with a certain $f_s.$ Let the continuous time domain signal $x(t)=2Co{s}^4(240t)$ is impulse sampled at a rate of $400$ samples $\frac{?}{sec}.$

$($a$)$ Sketch the $x(f)($show the distinct frequencies with magnitudes$)$ and decide Minimum sampling frequency $f_s$min$[Hz].(4)$

$($b$)$ Do you expect Aliasing effect? $($Yes$/$No$).$ Justify the reason. $(2)$

$($c$)$ Now decide the width of Guard band $[$in Hz $]$ if any, using the given sampling rate of $400$ samples $\frac{?}{sec}.[$Show spectral plot if needed$]$

$(4)$