A chirp signal is a sinusoid of continuously changing frequency. Chirps are frequently used to jam communication trans-missions. Consider the chirp

(a) A measure of the frequency of the chirp is the so-called instantaneous frequency which is defined as the derivative of the phase  in the cosine, i.e., IF(n) = d(θn² )/dn. Find the instantaneous frequency of the given chirp. Use MATLAB to plot x[n] for L = 256.

(b) Let L = 256 and use MATLAB to compute the DTFT of x[n] and to plot its magnitude. Indicate the range of discrete frequencies that would be jammed by the given chirp.

Transcribed Image Text:

x[n] = cos(en)u[n], 0 = ,0 < n