Matlab实现三角波调频连续波雷达信号仿真

% 绘制三角调频连续波 clc; clear all; close all; % 测试三角调频连续波FFT以及菲涅尔频率 % B = 400.e6; % 400MHz 带宽 % T = 10.e-6; % 10us 调制周期 % mu = 4 .* pi * B / T; % delt = linspace(-T/2,T/2,10001); % 1ns 采样间隔 % fc = 9.e9; % 9GHz 载频 % triangle = tripuls(delt,T); % triangle1 = triangle.*B; % tri_fre = triangle.*B; %triangle_frequency tri_fre % figure % % plot(delt*1e6,triangle); % % plot(delt,triangle); % % plot(delt*1e6,triangle1); % plot(delt,triangle1); % axis xy % % Ichannal = cos(0.5.*tri_fre.*delt); % Qchannal = sin(0.5.*tri_fre.*delt); % LFM = Ichannal + sqrt(-1) .* Qchannal; % complex signal % LFMFFT = fftshift(fft(LFM)); % figure % plot(Ichannal); % axis xy % figure % plot(Qchannal); % axis xy % figure % plot(abs(LFMFFT)); % axis xy %函数中频率带宽显示的就是菲涅尔频谱 close all clear all eps = 0.000001; %Enter pulse width and bandwidth B = 400.0e6; %400 MHZ bandwidth T = 10.e-6; %10 micro second pulse; % Compute alpha mu = 4. * pi * B / T; % Determine sampling times delt = linspace(-T/2., T/2., 10001); % 1 nano sceond sampling interval len = length(delt); len_up = round(len/2); len_down = len - len_up; % Compute the complex LFM representation % 三角波上调频信号 delt_up = delt(1:len_up); Ichannal_up = cos(mu .* delt_up.^2 / 2.); % Real part Qchannal_up = sin(mu .* delt_up.^2 / 2.); % Imaginary Part Ichannal = Ichannal_up; Qchannal = Qchannal_up; LFM = Ichannal + sqrt(-1) .* Qchannal; % complex signal %Compute the FFT of the LFM waveform LFMFFT_up = fftshift(fft(LFM,len)); LFMFFT = LFMFFT_up; % Plot the real and Immaginary parts and the spectrum freqlimit = 0.5 / 1.e-9;% the sampling interval 1 nano-second freq = linspace(-freqlimit/1.e6,freqlimit/1.e6,10001); figure(1) plot(delt_up*1e6,Ichannal,'k'); axis([-1 1 -1 1]) grid xlabel('Time - microsecs') ylabel('Real part') title('T = 10 Microsecond, B = 400 MHz') figure(2) plot(delt_up*1e6,Qchannal,'k'); axis([-1 1 -1 1]) grid xlabel('Time - microsecs') ylabel('Imaginary part') title('T = 10 Microsecond, B = 400 MHz') figure(3) plot(freq, abs(LFMFFT),'k'); %axis tight grid xlabel('Frequency - MHz') ylabel('Amplitude spectrum') title('Spectrum for an LFM waveform and T = 10 Microsecond, B = 400 MHZ') % 三角波下调频信号 delt_down = delt(len_up+1:len); Ichannal_down = cos(-mu .* delt_down.^2 / 2.); % Real part Qchannal_down = sin(-mu .* delt_down.^2 / 2.); % Imaginary Part Ichannal = Ichannal_down; Qchannal = Qchannal_down; LFM = Ichannal + sqrt(-1) .* Qchannal; % complex signal %Compute the FFT of the LFM waveform LFMFFT_down = fftshift(fft(LFM,len)); LFMFFT = LFMFFT_down; % Plot the real and Immaginary parts and the spectrum freqlimit = 0.5 / 1.e-9;% the sampling interval 1 nano-second freq = linspace(-freqlimit/1.e6,freqlimit/1.e6,10001); figure(4) plot(delt_down*1e6,Ichannal,'k'); axis([-1 1 -1 1]) grid xlabel('Time - microsecs') ylabel('Real part') title('T = 10 Microsecond, B = 400 MHz') figure(5) plot(delt_down*1e6,Qchannal,'k'); axis([-1 1 -1 1]) grid xlabel('Time - microsecs') ylabel('Imaginary part') title('T = 10 Microsecond, B = 400 MHz') figure(6) plot(freq, abs(LFMFFT),'k'); %axis tight grid xlabel('Frequency - MHz') ylabel('Amplitude spectrum') title('Spectrum for an LFM waveform and T = 10 Microsecond, B = 400 MHZ') % 完整的三角波调频连续波信号 Ichannal = [Ichannal_up Ichannal_down]; Qchannal = [Qchannal_up Qchannal_down]; LFMFFT = abs(LFMFFT_up) + abs(LFMFFT_down); % Plot the real and Immaginary parts and the spectrum freqlimit = 0.5 / 1.e-9;% the sampling interval 1 nano-second freq = linspace(-freqlimit/1.e6,freqlimit/1.e6,10001); figure(7) plot(delt*1e6,Ichannal,'k'); axis([-1 1 -1 1]) grid xlabel('Time - microsecs') ylabel('Real part') title('T = 10 Microsecond, B = 400 MHz') figure(8) plot(delt*1e6,Qchannal,'k'); axis([-1 1 -1 1]) grid xlabel('Time - microsecs') ylabel('Imaginary part') title('T = 10 Microsecond, B = 400 MHz') figure(9) plot(freq, abs(LFMFFT),'k'); %axis tight grid xlabel('Frequency - MHz') ylabel('Amplitude spectrum') title('Spectrum for an LFM waveform and T = 10 Microsecond, B = 400 MHZ')