PCM量化系統!!

Parameter Settings ----------------------------------

fs=1000; % oversampling freq. for generating signal waveform

ts=1/fs; % oversmaping period

Fs=100; % sampling freq

Ts=1/Fs; % sampling time

OVR=fs/Fs; % oversampling ratio

T=1; % obervation time

fm1=40; % freq. of signal #1

fm2=60; % freq. of signal #2

tx=0:Ts:T-Ts; % time axis of the observation period

Nfft=length(tx); % length of N-point FFT

%---------------------------------------------------------

% Signal Generation and Find Its Spectrum -------------

x1c=cos(2*pi*fm1*(0:ts:T-ts)); % signal waveform #1

x2c=cos(2*pi*fm2*(0:ts:T-ts)); % signal waveform #2

x1=cos(2*pi*fm1*tx);

x2=cos(2*pi*fm2*tx);

X1=fftshift(fft(x1,Nfft));

X2=fftshift(fft(x2,Nfft));

fx=-Fs/2:Fs/Nfft:Fs/2-Fs/Nfft; % freq. axis

%--------------------------------------------------------

% Plot Figures ---------------------------------------

%%% (a) Transmitted Signal # 1 and Its Spectrum

figure(1);

subplot(211);

plot(0:ts:T-ts,x1c);

hold on;

stem(tx,x1,'ro');

hold off;

legend('x1c', 'x1');

axis([0 0.2 1.2*min(x1c) 1.2*max(x1c)]);

title(['Signal and Its Samples, with Message freq. fm=' num2str(fm1)...

' Hz, Sampling freq. Fs=' num2str(Fs) ' Hz']);

Nfft=length(tx); % length of N-point FFT

%---------------------------------------------------------