kayforqpsk1.m

产生QPSK的matlab源程序

clc;
clear all;

Symbol = 4096;%%有关
Fs = 16e6;%%无关
Fc = 2.5e6;%%无关
Rs = 1e6;%%有关
a = 0.35;
T = 4;
SNR = 20;
Mk = Fs/Rs;%%无关

FIR = rcosfir(a ,[-T,T] ,Mk ,1 ,'sqrt');
Code = randint(1,Symbol,[0 1])*2-1 + j*(randint(1,Symbol,[0 1])*2-1);

noise = randn(1,Symbol*Mk)*(10^(-SNR/20));
Data = conv(upsample(Code,Mk),FIR);

% plot(real(Data));
QPSK = Data((1:Symbol*Mk)+T*Mk).*exp(j*2*pi*Fc/Fs*(1:Symbol*Mk));% + noise;

% figure(1)
% plot(10*log10(abs(fft(real(QPSK)))));

% h = zeros(1,101);
% fh = 0.2663;
% fl = 0.151;
% h = sin(fh*pi*((1:101)-50.01))/pi./((1:101)-50.01).*(0.54+0.46*cos(2*pi*((1:101)-50.01)/101))...
%     -sin(fl*pi*((1:101)-50.01))/pi./((1:101)-50.01).*(0.54+0.46*cos(2*pi*((1:101)-50.01)/101));
% QPSK1 = conv(QPSK,h);
% QPSK = QPSK1((1:Symbol*Mk)+50);

% figure(2)
% plot(10*log10(abs(fft(real(QPSK)))));

Fo = Fc;
Baseband = QPSK.*exp(-j*2*pi*Fo/Fs*(1:Symbol*Mk));
Baseband1 = conv(Baseband,FIR);
Baseband2 = Baseband1((1:Symbol*Mk)+T*Mk);
% plot(real(Baseband2));