how to use matlab code tp plot following

Question

praveen yadav 2017-9-24

回答： Image Analyst 2017-9-24

(a) plot s(t) and its magnitude frequency spectrum

(b) plot the modified signal x(t)=s(t)*cos(2πfct) in both time and frequency spectrum.

(c) Assuming a perfect coherent demodulation, plot the output (in time and magnitude spectrum) of the demodulator mixer.

(d) Plot the output (in time and magnitude spectrum) of the ideal low pass filters with bandwidth of 1Hz and 5Hz respectively.

(e) Repeat parts(c) and (d) assuming a non-ideal mixer with phase error of 5 degree

(f) Repeat parts(c) and (d) assuming a non-ideal mixer with phase error 0.2Hz

Walter Roberson 2017-9-24

Walter Roberson 2017-9-24

s(t) = mod(ceil(t), 2) * 2 - 1;

Answer 1

Image Analyst 2017-9-24

Hints:

t = linspace(0, 4, 1000);
x = s .* cos(2 * pi * f * c * t)

Function hints: plot(), linspace(), fft() or pwelch(), abs(), real(), imag(), etc.