%升余弦濾波器+PSK調(diào)制(單路)
%以碼元速率1.2288M為例，濾波器基本調(diào)整完畢，頻譜關(guān)系得到整理
clc;%清除命令窗口
clear all;%清除工作空間workspace,以釋放內(nèi)存
close all;
%生成隨機(jī)數(shù)
%以下為QPSK調(diào)制
x_length=1000;                       %  信息碼元個(gè)數(shù)
Rb=1228800/2;%碼元速率1.2288M
k=1;                %一個(gè)碼元間隔包括1個(gè)載波周期/2
k2=16;
fc=k*Rb;                             %  載波頻率，
fs=fc*k2;                             %  信號(hào)采樣率
x_size=k*k2;
%y=1:x_size;                         %  采樣時(shí)間序列，每個(gè)碼元采x_size點(diǎn)
x_i=randsrc(1,x_length,[-1,1]);%sign(rand(1,x_length)-0.5);       正負(fù)號(hào)函數(shù)sign，產(chǎn)生隨機(jī)碼
%x_q=randsrc(1,x_length,[-1,1]);
for i=1:x_length
    baseband_i(1,1+(i-1)*x_size:i*x_size)=x_i(i);%將碼元展寬x_size倍
%    baseband_q(1,1+(i-1)*x_size:i*x_size)=x_q(i);%將碼元展寬x_size倍
end
%將i路提前半個(gè)碼元，相當(dāng)于將q路延遲半個(gè)碼元
%basefore_i=zeros(1,length(baseband_i));
%basefore_i(1:length(baseband_i)-x_size/2)=baseband_i(x_size/2+1:length(baseband_i));

%基帶濾波
%n=15;%濾波器階數(shù)
%shengyuxuian=myfilter(n,fs/fc);
%filtoutI=filter(shengyuxuian,1,baseband_i);
filtout_I= rcosflt(x_i,1,x_size);%利用現(xiàn)成的升余弦函數(shù)
filtoutI=filtout_I(2.5*x_size+1:x_length*x_size+2.5*x_size)';

%baseband_i(2,:)=filtoutI;

%產(chǎn)生載波
%carry_i(1:x_length*x_size)=cos(2*pi*fc*(1:x_length*x_size)/fs+pi/4); 
%carry_q(1:x_length*x_size)=sin(2*pi*fc*(1:x_length*x_size)/fs+pi/4); 
%BPSK調(diào)制
%s_i=filtoutI.*carry_i;
%s_q=baseband_q.*carry_q;
%sfore_i=basefore_i.*carry_i;
%輸出QPSK信號(hào)
%sqpsk=s_i+s_q;
%soqpsk=sfore_i+s_q;

%調(diào)制信號(hào)的付利葉變換
%fft_s_i=abs(fft(s_i));             
%n=size(s_i,2);     %FFT后數(shù)據(jù)點(diǎn)數(shù)目
%f=1:fs/n:fs;
%m=fc/fs*n*2;       %此處m=fs/4=2fc

%基帶信號(hào)的付利葉變換
fft_baseband_i=abs(fft(baseband_i(1,:)));             
fft_filtoutI=abs(fft(filtoutI));             
n=size(baseband_i,2);%FFT后數(shù)據(jù)點(diǎn)數(shù)目,d = size(X)返回二維向量，分別為矩陣X行數(shù)和列數(shù)
f=1:fs/n:fs;
m=fc/fs*n*2;       %此處m=fs/4=2fc
 %圖1,調(diào)制信號(hào)頻譜圖
figure(2)
subplot(2,1,1)
%plot(f(1,1:m),fft_s_i(1,1:m))
%title('信號(hào)頻譜(BPSK)')
%grid on
%subplot(3,1,2)
plot(f(1,1:2*m),fft_baseband_i(1,1:2*m))
title('基帶信號(hào)頻譜')
grid on
subplot(2,1,2)
plot(f(1,1:2*m),fft_filtoutI(1,1:2*m))
title('基帶信號(hào)頻譜')
grid on


%figure(2)
%subplot(3,1,1)
%plot(baseband_i(1,:), 'DisplayName', 'frameinsertI', 'YDataSource', 'frameinsertI'); 
%title('濾波器輸入信號(hào)')
%grid on
%subplot(3,1,2)
%plot(filtoutI, 'DisplayName', 'frameoutI', 'YDataSource', 'frameoutI'); 
%title('濾波器輸出信號(hào)')
%grid on
%subplot(3,1,3)
%plot(s_i, 'DisplayName', 'frameoutI', 'YDataSource', 'frameoutI'); 
%grid on
%title('I路BPSK調(diào)制信號(hào)')