基于MATLAB的声波测距

%%单个回音%% [x,fs,bits] = wavread('music11.wav'); t = (0:length(x)-1)/fs; figure(1); subplot(3,1,1); plot(x);xlabel('采样点');ylabel('幅度'); title('原信号'); y = fft(x); subplot(3,1,2);plot(abs(y));title('原信号幅值'); subplot(3,1,3);plot(angle(y));title('原信号相位'); %sound(x,fs);pause(5); %回声信号 x1 = x;x2 = x; x1 = [x1',zeros(1,20000)]; x2 = [zeros(1,12000),0.6*x2',zeros(1,8000)]; y2 = x1+x2; y2_2 = fft(y2); figure(2); subplot(3,1,1);plot(y2);title('回声信号'); subplot(3,1,2);plot(abs(y2_2));title('回声信号幅值'); subplot(3,1,3);plot(angle(y2_2));title('回声信号相位'); %sound(y2,fs); %相关性测距 h = xcorr(y2); figure(3); subplot(2,1,1);plot(abs(h));title('相关函数'); %h1 = h(250000:260000); %[h11,h11_location] = max(h1); %h11_location = h11_location+250000; %subplot(4,1,2);plot(h1);title('最大点'); %h2 = h(263000:270000); %[h22,h22_location] = max(h2); %h22_location = h22_location+263000-h11_location; %subplot(4,1,3);plot(h2);title('次大点'); %T2 = h22_location/fs; %d = 340*T2/2;%物理距离 %a = h22/h11;%衰减比 [h1,h1_1] = max(h); hh1 = h; hh1(1,h1_1-7000:h1_1+7000) = 0; subplot(2,1,2);plot(hh1);title('次大点'); [h2,h2_2] = max(hh1); N = abs(h1_1-h2_2) a = h2/h1%衰减比 ts = N/fs;%延时时间 d = 340*ts/2%物理距离 %消除回音 b=1; A = zeros(1,20000);A(1) = 1;A(12001)=0.6; z = filter(b,A,y2); %sound(z,fs,bits); z1 = fft(z,fs); figure(4); subplot(2,1,2);plot(abs(z1));title('滤波幅值'); subplot(2,1,1);plot(angle(z1));title('滤波相位'); figure(5); subplot(2,1,1);plot(x);title('原始信号'); subplot(2,1,2);plot(z);title('滤波信号');