雷达系统仿真matlab代码.doc
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雷达系统仿真matlab代码.doc
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%===========================================================================================%
%该程序完成16个脉冲信号的【脉压、动目标显示/动目标检测(MTI/MTD)】
%===========================================================================================%
%程序中根据每个学生学号的末尾三位(依次为XYZ)来决定仿真参数,034
%目标距离为[300080259000+(Y*10+Z)*2008025],4个目标
%目标速度为[500(Y*10+X+Z)*6100]
%===========================================================================================%
closeall;%关闭所有图形
clearall;%清除所有变量
clc;
%===================================================================================%
%雷达参数%
%===================================================================================%
C=3.0e8;%光速(m/s)
RF=3.140e9/2;%雷达射频1.57GHz
Lambda=C/RF;%雷达工作波长
PulseNumber=16;%回波脉冲数
BandWidth=2.0e6;%发射信号带宽
TimeWidth=42.0e-6;%发射信号时宽
PRT=240e-6;%雷达发射脉冲重复周期(s),240us对应1/2*240*300=36000米最大无模糊距离
PRF=1/PRT;
Fs=2.0e6;%采样频率
NoisePower=-12;%(dB);%噪声功率(目标为0dB)
%---------------------------------------------------------------%
SampleNumber=fix(Fs*PRT);%计算一个脉冲周期的采样点数480;
TotalNumber=SampleNumber*PulseNumber;%总的采样点数480*16=;
BlindNumber=fix(Fs*TimeWidth);%计算一个脉冲周期的盲区-遮挡样点数;
%===================================================================================%
%目标参数%
%===================================================================================%
TargetNumber=4;%目标个数
SigPower(1:
TargetNumber)=[1110.25];%目标功率,无量纲
TargetDistance(1:
TargetNumber)=[30008025158008025];%目标距离,单位m距离参数为[300080259000+(Y*10+Z)*2008025]
DelayNumber(1:
TargetNumber)=fix(Fs*2*TargetDistance(1:
TargetNumber)/C);%把目标距离换算成采样点(距离门)fix函数向0靠拢取整
TargetVelocity(1:
TargetNumber)=[500204100];%目标径向速度单位m/s速度参数为[500(Y*10+X+Z)*6100]
TargetFd(1:
TargetNumber)=2*TargetVelocity(1:
TargetNumber)/Lambda;%计算目标多卜勒频移2v/λ
%====================================================================================%
%产生线性调频信号%
%====================================================================================%
number=fix(Fs*TimeWidth);%回波的采样点数=脉压系数长度=暂态点数目+1
ifrem(number,2)~=0%rem求余
number=number+1;
end%把number变为偶数
fori=-fix(number/2):
fix(number/2)-1
Chirp(i+fix(number/2)+1)=exp(j*(pi*(BandWidth/TimeWidth)*(i/Fs)^2));%exp(j*fi)*,产生复数矩阵Chirp
end
coeff=conj(fliplr(Chirp));%把Chirp矩阵翻转并把复数共轭,产生脉压系数
figure
(1);%脉压系数的实部
plot(real(Chirp));axis([090-1.51.5]);title('脉压系数实部');
%-------------------------产生目标回波串-----------------------------------------------------------------------------------------%
%-------------------------产生前3个目标的回波串-------%
SignalAll=zeros(1,TotalNumber);%所有脉冲的信号,先填0
fork=1:
TargetNumber-1%依次产生各个目标
SignalTemp=zeros(1,SampleNumber);%一个PRT
SignalTemp(DelayNumber(k)+1:
DelayNumber(k)+number)=sqrt(SigPower(k))*Chirp;%一个脉冲的1个目标(未加多普勒速度)(DelayNumber(k)+1):
(DelayNumber(k)+number)
Signal=zeros(1,TotalNumber);
fori=1:
PulseNumber%16个回波脉冲
Signal((i-1)*SampleNumber+1:
i*SampleNumber)=SignalTemp;%每个目标把16个SignalTemp排在一起
end
FreqMove=exp(j*2*pi*TargetFd(k)*(0:
TotalNumber-1)/Fs);%目标的多普勒速度*时间=目标的多普勒相移
Signal=Signal.*FreqMove;%加上多普勒速度后的16个脉冲1个目标
SignalAll=SignalAll+Signal;%加上多普勒速度后的16个脉冲4个目标
end
%%-------------------------产生第4个目标的回波串-------%
fi=pi/3;
SignalTemp=zeros(1,SampleNumber);%一个脉冲
SignalTemp(DelayNumber(4)+1:
DelayNumber(4)+number)=sqrt(SigPower(4))*exp(j*fi)*Chirp;%一个脉冲的1个目标(未加多普勒速度)
Signal=zeros(1,TotalNumber);
fori=1:
PulseNumber
Signal((i-1)*SampleNumber+1:
i*SampleNumber)=SignalTemp;
end
FreqMove=exp(j*2*pi*TargetFd(4)*(0:
TotalNumber-1)/Fs);%目标的多普勒速度*时间=目标的多普勒相移
Signal=Signal.*FreqMove;
SignalAll=SignalAll+Signal;
figure
(2);
subplot(2,1,1);plot(real(SignalAll),'r-');title('目标信号的实部');gridon;zoomon;
subplot(2,1,2);plot(imag(SignalAll));title('目标信号的虚部');gridon;zoomon;
%====================================================================================%
%产生系统噪声信号%
%====================================================================================%
SystemNoise=normrnd(0,10^(NoisePower/10),1,TotalNumber)+j*normrnd(0,10^(NoisePower/10),1,TotalNumber);
%均值为0,标准差为10^(NoisePower/10)的噪声
%====================================================================================%
%总的回波信号%
%====================================================================================%
Echo=SignalAll+SystemNoise;%+SeaClutter+TerraClutter,加噪声之后的回波
fori=1:
PulseNumber%在接收机闭锁期,接收的回波为0
Echo((i-1)*SampleNumber+1:
(i-1)*SampleNumber+number)=0;%发射时接收为0
end
figure(3);%加噪声之后的总回波信号
subplot(2,1,1);plot(real(Echo),'r-');title('总回波信号的实部,闭锁期为0');
subplot(2,1,2);plot(imag(Echo));title('总回波信号的虚部,闭锁期为0');
%================================时域脉压=================================%
pc_time0=conv(Echo,coeff);%pc_time0为Echo和coeff的卷积
pc_time1=pc_time0(number:
TotalNumber+number-1);%去掉暂态点number-1个
figure(4);%时域脉压结果的幅度
subplot(2,1,1);plot(abs(pc_time0),'r-');title('时域脉压结果的幅度,有暂态点');%pc_time0的模的曲线
subplot(2,1,2);plot(abs(pc_time1));title('时域脉压结果的幅度,无暂态点');%pc_time1的模的曲线
%================================频域脉压=================================%
Echo_fft=fft(Echo,8192);%理应进行TotalNumber+number-1点FFT,但为了提高运算速度,进行了8192点的FFT
coeff_fft=fft(coeff,8192);
pc_fft=Echo_fft.*coeff_fft;
pc_freq0=ifft(pc_fft);
figure(5);
subplot(2,1,1);plot(abs(pc_freq0(1:
TotalNumber+number-1)));title('频域脉压结果的幅度,有前暂态点');
subplot(2,1,2);plot(abs(pc_time0(1:
TotalNumber+number-1)-pc_freq0(1:
TotalNumber+number-1)),'r');title('时域和频域脉压的差别');
pc_freq1=pc_freq0(number:
TotalNumber+number-1);%去掉暂态点number-1个,后填充点若干(8192-number+1-TotalNumber)
%================按照脉冲号、距离门号重排数据=================================%
fori=1:
PulseNumber
pc(i,1:
SampleNumber)=pc_freq1((i-1)*SampleNumber+1:
i*SampleNumber);%每个PRT为一行,每行480个采样点的数据
end
figure(6);
plot(abs(pc(1,:
)));title('频域脉压结果的幅度,没有暂态点');
%================MTI(动目标显示),对消静止目标和低速目标---可抑制杂波=================================%
fori=1:
PulseNumber-1%滑动对消,少了一个脉冲
mti(i,:
)=pc(i+1,:
)-pc(i,:
);
end
figure(7);
mesh(abs(mti));title('MTIresult');
%================MTD(动目标检测),区分不同速度的目标,有测速作用=================================%
mtd=zeros(PulseNumber,SampleNumber);
fori=1:
SampleNumber
buff(1:
PulseNumber)=pc(1:
PulseNumber,i);
buff_fft=fft(buff);
mtd(1:
PulseNumber,i)=buff_fft(1:
PulseNumber);
end
figure(8);mesh(abs(mtd));title('MTDresult');
%=======================================虚实矩阵转换========================================%
coeff_fft_c=zeros(1,2*8192);
fori=1:
8192
coeff_fft_c(2*i-1)=real(coeff_fft(i));
coeff_fft_c(2*i)=imag(coeff_fft(i));
end
echo_c=zeros(1,2*TotalNumber);
fori=1:
TotalNumber
echo_c(2*i-1)=real(Echo(i));
echo_c(2*i)=imag(Echo(i));
end
%===========================以下是为DSP程序提供回波数据、脉压系数===============================%
%fo=fopen('F:
\mystudy\Visual_DSP_test\test_1\coeff_fft_c.dat','wt');%频域脉压系数
%fori=1:
2*8192
%fprintf(fo,'%f,\r\n',coeff_fft_c(i));
%end
%fclose(fo);
%
%fo=fopen('F:
\mystudy\Visual_DSP_test\test_1\echo_c.dat','wt');%16次回波的
%fori=1:
2*TotalNumber
%fprintf(fo,'%f,\r\n',echo_c(i));
%end
%fclose(fo);
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