It is desired to determine the DFT of the analogue signal x (t) = 25 cos(10 Πt)cos(400Πt).
(a) Find the Nyquist rate of the signal.
(b) What is the record (signal) length if the desired frequency resolution is 5Hz?
(c) If the Nyquist rate from part (a) and the record length found in part (b) are used, find the number of points that will be contained in the DFT.
(d) Use the MATLAB function fft to find and plot the DFT X (k). Add the frequency scale (in hertz) to the diagram.
(e) If the sampling frequency is doubled, How is X (k) changed?