LAB ASSIGNMENT 10 (due 04/16/14) _________________________________ (20 pts.) The signal in the file AUDIO10.wav consists of N samples of a signal y, which is a modulated version of a bandlimited audio signal x: y[n] = x[n]*cos(w*n), n = 0:N-1 Here, w = K*(2*pi/N) for some K. The objective is to demodulate y, i.e., obtain x. i) Use WAVREAD to import the vector y. What is its length N and sampling rate Fs? Listen to y using SOUNDSC. ii) Compute the DFT Y of y and plot its magnitude. Using the modulation property of the DFT and noting symmetries in the figure, determine K. iii) Using the value of K found in (ii), reconstruct the DFT X from Y. iv) Invert X to obtain your version of x (it should be real!). Play it back using SOUNDSC to make sure the result is satisfactory. Encode x into a .WAV file using wavwrite(x,fs,'lastname_labhw_10.wav') (If you get a warning about clipping, replace x by 0.99*x/max(abs(x)).) ___________________________________________________________________________ Submit a zip or rar package containing the following files (use exact file names as shown): lastname_labhw_10.m State the values of N, Fs and K, with an explanation of how you obtained K. You only need to include the MATLAB code used in obtaining x (time domain) from Y (frequency domain) in steps. (iii) and (iv). Useful comments should be given. lastname_labhw_10.wav From (iv) above. The zip or rar package should be named as lastname_labhw_10.zip / .rar, and should be uploaded from the upload link on the course lab web page , or if not possible, emailed to enee222S2013@gmail.com.