p4pulsecompressiondemo.m

实现了P4多相码的产生和脉压

% function P4PulseCompressionDemo
%  fuxiongjun @ 2006-08-15

clear;
close all;

cj=sqrt(-1);

% P4多相码的产生
m=16;
for i=1:m
    phasevalue (i)=pi/m*(i-1)^2-pi*(i-1);
end
% module to 2pi
real_code_2pi=rem(phasevalue,2*pi);   

% convert to complex data 
Polyphase_signal=exp(cj*real_code_2pi);

% matched filtering (pulse compression)
MF=conj(fliplr(Polyphase_signal));        % 参考信号

% MF_Out=conv(Polyphase_signal,MF);      % 匹配滤波输出，工程上应该在频域快速卷积,as below

% quick conv using FFT
Polyphase_signal_addzeros=[ Polyphase_signal zeros(1,length(Polyphase_signal)-1)];
MF_addzeros=[ MF zeros(1,length(Polyphase_signal)-1)];
Polyphase_signal_F=fft(Polyphase_signal_addzeros);
MF_F=fft(MF_addzeros);
MF_Out_F=Polyphase_signal_F.*MF_F;
MF_Out=ifft(MF_Out_F);

figure(1);
plot(abs(MF_Out));
title('polyphase code matched filter output')