clear all;
close all;

A = 1;
fc = 2;                                      %2Hz           
N_sample = 8;
N = 500;                                     %碼元數
Ts = 1;                                      %1Baud/s

dt = Ts/fc/N_sample;                         %波形采樣間隔
t = 0:dt:N*Ts-dt;
Lt = length(t);
%產生二進制信源
d = sign(randn(1,N));
dd = sigexpand((d + 1)/2,fc*N_sample);
gt = ones(1,fc*N_sample);                    %NRZ波形

figure(1)
subplot(211);                                %輸入NRZ信號波形(單極性)
d_NRZ = conv(dd,gt);
plot(t,d_NRZ(1:length(t)));
axis([0 10 0 1.2]);
ylabel('輸入信號');

subplot(212);                                %輸入NRZ頻譜
[f,d_NRZf] = T2F(t,d_NRZ(1:length(t)));
plot(f,10*log10(abs(d_NRZf).^2/Ts));
axis([-2 2 -50 30]);
ylabel('輸入信號功率譜密度(dB/Hz)');

figure(2)
%2PSK信號
ht = A*cos(2*pi*fc*t);
d_2psk = 2*d_NRZ-1;
s_2psk = d_2psk(1:Lt).*ht;
subplot(211)
plot(t,s_2psk);
axis([0 10 -1.2 1.2]);
ylabel('2psk');

subplot(212)
[f,s_2pskf] = T2F(t,s_2psk);
plot(f,10*log10(abs(s_2pskf).^2/Ts));
axis([-fc-4 fc+4 -50 30]);
ylabel('2psk功率譜密度(dB/Hz)');