合成孔径声纳成像仿真 单一阵元 收发合置 停走停

%% 合成孔径声纳成像仿真 单一阵元 收发合置 停走停

clear all; clc; close all;

%% %系统参数

c = 1500;   %声速1500m/s;

pulseT = 10e-3;  %发射信号脉宽10ms

f0 = 10e3;  %发射信号中心频率20kHz

B = 6e3;    %发射信号带宽8kHz

fs = 50e3; %系统采样率100kHz

d = 0.2;    %系统实孔径0.2m

v = 0.1;    %系统速度0.1m/s

Ts = 0.08;   %系统采样时长0.08s;

T = 1;      %系统采样周期1s

Y =  40;    %方位向成像范围0-40m

tr1 = 30;   %目标1距离向位置

ty1 = 20;   %目标1方位向位置

tr2 = 35;   %目标2距离向位置

ty2 = 19;   %目标2方位向位置

tr3 = 35;   %目标2距离向位置

ty3 = 20;   %目标2方位向位置

lamda = c/f0;   %信号波长

theta3dB = lamda/d; %系统3dB开角

sigT = 1/fs:1/fs:pulseT;    %信号时间点

signal = chirp(sigT, f0-B/2,pulseT, f0+B/2);    %发射信号

%===============================================================

% 仿真目标回波信号

num = floor(40/v/T); %总采样数据个数

recSigT = 1/fs:1/fs:Ts;  %采样数据时间点

recSignals = zeros(num, length(recSigT));

recSignals1 = zeros(num, length(recSigT));

recSignals2 = zeros(num, length(recSigT));

recSignals3 = zeros(num, length(recSigT));

y11 = ty1-tr1*theta3dB/2;      %声纳能够接受到目标回波信号的方位向范围

y12 = ty1+tr1*theta3dB/2;

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for i = 1:num    

if i*v >= y11 && i*v <= y12        

delay = sqrt(tr1^2+(ty1-i*v)^2)*2/c;        

delayNum = round(delay*fs);        

recSignals1(i,:) = [ zeros(1, delayNum), signal, zeros(1, length(recSigT)-delayNum-length(signal)) ];    

end

end

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y21 = ty2-tr2*theta3dB/2;      %声纳能够接受到目标回波信号的方位向范围

y22 = ty2+tr2*theta3dB/2;

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for i = 1:num    

if i*v >= y21 && i*v <= y22        

delay = sqrt(tr2^2+(ty2-i*v)^2)*2/c;        

delayNum = round(delay*fs);        

recSignals2(i,:) = [ zeros(1, delayNum), signal, zeros(1, length(recSigT)-delayNum-length(signal)) ];   

  end

end

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y31 = ty3-tr3*theta3dB/2;      %声纳能够接受到目标回波信号的方位向范围

y32 = ty3+tr3*theta3dB/2;

-------------------------------------------------------------------------------------------------

for i = 1:num    

if i*v >= y31 && i*v <= y32        

delay = sqrt(tr3^2+(ty3-i*v)^2)*2/c;        

delayNum = round(delay*fs);        

recSignals3(i,:) = [ zeros(1, delayNum), signal, zeros(1, length(recSigT)-delayNum-length(signal)) ];    

end

end

% recSignals = recSignals1 + recSignals2 + recSignals3; recSignals = recSignals1;

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figure;

imagesc(recSignals);

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% 距离向匹配滤波

tempData = zeros(num, length(recSigT)*2-1);

dataR = zeros(num, length(recSigT));

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for i=1:num    

tempData(i,:) = xcorr(recSignals(i,:), signal);    

dataR(i,:) = (tempData(i,floor(length(tempData(i,:))/2+1):end));

end

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figure;

imagesc(abs(dataR));

% 逐点成像

imgR = Ts*c/2;  %距离向成像范围

imgY = Y;       %方位向成像范围

resolution = 0.05;   %成像分辨率0.1m

imgSizeX = floor(imgR/resolution);

imgSizeY = floor(imgY/resolution);

imgData = zeros(imgSizeY, imgSizeX);

-------------------------------------------------------------------------

for row = 1:imgSizeX    

for col = 1:imgSizeY        

posR = row*resolution;        

posY = col*resolution;        

sum = 0;        

for i = 1:num            

y1 = posY-posR*theta3dB/2;      %声纳能够接受到目标回波信号的方位向范围            

y2 = posY+posR*theta3dB/2;            

if i*v < y1 || i*v > y2                

continue;            

end            

delay = sqrt(posR^2+(posY-i*v)^2)*2/c;            

if delay >= Ts                

continue;            

end            

sum = sum + dataR(i, round(delay*fs));        

end        

imgData(col, row) = sum;    

end

end

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figure;

imagesc(imgData);

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figure;

imagesc(abs(imgData));

------------------------------------------------------------------

figure;

surf(abs(imgData)); shading interp;

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