距离波们拖引干扰

%=======舷外有源干扰距离波门拖引干扰仿真==============================%
function []=main()
clc;
clear all;
close all;
%=======================仿真参数======================================%
c=3e8; %光速
fo=1e6; %中心频率
fs=4e6; %采样频率
ts=1/fs;
tau=100e-6; %脉冲宽度
Tr=1e-3; %脉冲重复周期
N=5; %雷达发射脉冲个数
R=30e3; %弹目距离
t_r=2*R/c; %回波时延
A=2.5; %干扰信号与回波信号幅度比
dlt_t=25e-6;%转发时延
B=1e6;%信号带宽
k=B/tau;%调频斜率
%%
t=0:ts:Tr-ts;
rect=zeros(1,length(t)); %产生调制函数矩形脉冲串
for i=1:length(t)
if t(i)>=(0+t_r)&t(i)<=(tau+t_r)
rect(i)=1;
end
end
%%
t=0:ts:N*Tr-ts;
Num=N*Tr/ts;
Signal_Radar=repmat(rect,1,N);%目标回波信号
% S=cos(2*pi*fo*(t-t_r));
S=cos(2*pi*(fo*(t-t_r)+0.5*k*(t-t_r).^2));
Signal_Radar=Signal_Radar.*S;
t1=0:ts:Tr+dlt_t-ts;
rect1=zeros(1,length(t1)); %产生调制函数矩形脉冲串
for i=1:length(t)
if t(i)>=(0+t_r)&t(i)<=(tau+t_r)
rect1(i)=1;
end
end
t=0:ts:N*(Tr+dlt_t)-ts;
Num=N*(Tr+dlt_t)/ts;
Signal_Jam=repmat(rect1,1,N);%干扰信号
Signal_Jam=A*Signal_Jam(1:length(S)).*S;
figure
subplot(211)
plot(Signal_Radar)
ylim([-3,3])
xlabel('采样点')
ylabel('信号幅度')
title('舰船回波信号')
subplot(212)
plot(Signal_Jam,'r')
ylim([-3,3])
xlabel('采样点')
ylabel('信号幅度')
title('舷外干扰拖引信号')
%=============距离波门拖引效果图==================================%
v=1000;%拖引速度
t=0:ts:Tr-ts;
SampleNumber=length(t);
jlbm=zeros(1,SampleNumber); %波门宽度一般为脉冲宽度
Signal_Radar_Single=Signal_Radar(1:SampleNumber);%单脉冲目标回波信号
Signal_Jam_Single=A*Signal_Radar(1:SampleNumber);%单脉冲干扰回波信号
Signal_Radar_Single_match=abs(fftshift(ifft(fft( Signal_Radar_Single).*fft(conj(fliplr(Signal_Radar_Single))))));%脉冲压缩
Signal_Jam_Single_match=abs(fftshift(ifft(fft( Signal_Jam_Single).*fft(conj(fliplr(Signal_Jam_Single))))));
%***********停拖期*****************************************************
%假设tt为0~1s期间为停拖期 t1=1s
t1=1;
figure
subplot(2,2,1)
plot((1:SampleNumber),Signal_Radar_Single_match);
hold on
plot((1:SampleNumber),Signal_Jam_Single_match,'r');
[mem,Pos]=max(Signal_Jam_Single_match);
jlbm((Pos-0.5*tau*fs+1):(Pos+0.5*tau*fs))=400;
plot((1:SampleNumber),jlbm,'black');
xlabel('采样点数');
ylabel('幅度');
title('t=1s时距离波门拖引效果');
jlbm=zeros(1,SampleNumber);

%*************拖引期（拖引时间tt=2s）***************************************************
tt=2;
RJ=R+v*(tt-t1);
dlt_t=2*v*(tt-t1)/c;

delayNum=fix(dlt_t*fs);
Signal_Jam_Single_Tuoyin1=zeros(1,SampleNumber);
Signal_Jam_Single_Tuoyin1(delayNum+1:SampleNumber+delayNum)=Signal_Jam_Single_match;
subplot(2,2,2)
plot((1:SampleNumber),Signal_Radar_Single_match);
hold on
plot((1:SampleNumber),Signal_Jam_Single_Tuoyin1(1:SampleNumber),'r')
[mem,Pos]=max(Signal_Jam_Single_Tuoyin1);
jlbm((Pos-0.5*tau*fs+1):(Pos+0.5*tau*fs))=400;
plot((1:SampleNumber),jlbm,'black');
xlabel('采样点数');
ylabel('幅度');
title('t=2s时距离波门拖引效果');
jlbm=zeros(1,SampleNumber);
%**********************拖引期（拖引时间tt=5s）******************************************
tt=5;
RJ=R+v*(tt-t1);
dlt_t=2*v*(tt-t1)/c;
delayNum=fix(dlt_t*fs);
Signal_Jam_Single_Tuoyin2=zeros(1,SampleNumber);
Signal_Jam_Single_Tuoyin2(delayNum+1:SampleNumber+delayNum)=Signal_Jam_Single_match;
subplot(2,2,3)
plot((1:SampleNumber),Signal_Radar_Single_match);
hold on
plot((1:SampleNumber),Signal_Jam_Single_Tuoyin2(1:SampleNumber),'r')
[mem,Pos]=max(Signal_Jam_Single_Tuoyin2);
jlbm((Pos-0.5*tau*fs+1):(Pos+0.5*tau*fs))=400;
plot((1:SampleNumber),jlbm,'black');
xlabel('采样点数');
ylabel('幅度');
title('t=5s时距离波门拖引效果');
jlbm=zeros(1,SampleNumber);
%***********************拖引期（拖引时间tt=10s）*****************************************
tt=10;
RJ=R+v*(tt-t1);
dlt_t=2*v*(tt-t1)/c;
delayNum=fix(dlt_t*fs);
Signal_Jam_Single_Tuoyin3=zeros(1,SampleNumber);
Signal_Jam_Single_Tuoyin3(delayNum+1:SampleNumber+delayNum)=Signal_Jam_Single_match;
subplot(2,2,4)
plot((1:SampleNumber),Signal_Radar_Single_match);
hold on
plot((1:SampleNumber),Signal_Jam_Single_Tuoyin3(1:SampleNumber),'r')
[mem,Pos]=max(Signal_Jam_Single_Tuoyin3);
jlbm((Pos-0.5*tau*fs+1):(Pos+0.5*tau*fs))=400;
plot((1:SampleNumber),jlbm,'black');
xlabel('采样点数');
ylabel('幅度');
title('t=10s时距离波门拖引效果');
jlbm=zeros(1,SampleNumber);


function [x_r,x_i]=chirp_signal(A,fs,W,B,pulse,T)

N=fix(fs*pulse); %脉冲宽度
M=fix(fs*T); %脉冲重复周期
u=0.5*B/pulse; %调频斜率

i=1:N;
x_r(i)=A*cos(2*pi*(W*i/(fs)+u*i.*i/(fs^2))); %脉内线性调频信号调制
x_i(i)=A*sin(2*pi*(W*i/(fs)+u*i.*i/(fs^2)));
i=N:M;
x_r(i)=0;
x_i(i)=0;