quiz9_solution - figure(1); %plots sound wave amp vs. time...

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1 %KEYPAD - A script that loads tone.dat, an ascii file %with column 1 giving the sound wave amplitude, into a MATLAB array, %plots sound wave amplitude vs. time, takes the fft of the input data, %and plots power vs. frequency. Note the sampling frequency is 8192 samples %per sec and tone.dat has 4096 data points. %File written by S.C. Tegler. Last modified 3/31/11. %--------------------------------------------------- load tone.dat -ascii %load ascii file signal = tone(:,1); %create signal vector L = length(signal); %length of signal vector t = 0:(1/8192):(L-1)*(1/8192); %create time vector corresponding to %signal vector
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Unformatted text preview: figure(1); %plots sound wave amp vs. time in sec plot(t,signal); xlabel( 'Time (sec)' ); ylabel( 'Sound Wave Amplitude' ); title( 'Key Signal' ); %axis([0.25 0.26 -0.8 0.8]); Y = fft(signal); %fft of sound wave signal Y(1) = 0; %set first element of fft output to 0 Power = abs(Y).^2; %computes power of fft output dv = 8192/4096; %computes frequency interval v = 0:dv:8191; %creates frequency vector figure(2); %plots power spectrum upto Nyquist plot(v(1:L/2),Power(1:L/2)); %frequency xlabel( 'Frequency (Hz)' ); ylabel( 'Power' ); title( 'Frequencies are 776 and 1208 Hz = Key 4' ); 2...
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quiz9_solution - figure(1); %plots sound wave amp vs. time...

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