随机信号分析仿真

1、随机信号分析原理大作业报告专业:水声工程姓名: xxx学号:xxxxxxxxxx题目要求:给定一个白噪声信号,它的均值和方差自定。1.设计一个线性滤波器,使该滤波器的输出为一个窄带信号。并给出该窄带信号在不同的3个典型中心频率和带宽时的波形。2.对该滤波器输出的上述窄带信号,用莱斯表示法对其进行建模,画出(t a和(t b的波形。3.计算上述3种窄带信号对应的瞬时频率和瞬时相位,并进行包络检测。整个频率区间,即 图6 滤波器2输出信号的时域波形 附件一滤波器1输出信号仿真程序clear allclose allclc%产生高斯白噪声N=25000; %序列长度my_var = 2;noise

2、= sqrt(my_var*randn(1,N;%均值为0,方差为2 figure(1plot(noisetitle('均值为0方差为2的高斯白噪声'grid onfs = 25000;%采样频率f0 = 1000;%中心频率%滤波器f_pass = 900 1100;omega_pass = 2*f_pass/fs;b = fir1(192,omega_pass;figure(2freqz(b,1,1024%滤波器幅度和相位图像grid on%噪声通过窄带滤波器filter_outpu = filter(b,1,noise;figure(3plot(filter_output

3、itle('窄带信号在时域的波形'grid on%做fft变换Nfft = fs;fft_x = fft(filter_outpu,Nfft;ff = 0:fs/Nfft:fs-fs/Nfft;figure(4plot(ff,20*log10(abs(fft_x%窄带信号的频谱title('窄带信号的频谱'xlabel('频率 Hz'ylabel('幅度 dB'grid on%窄带信号在时域的波形X_t = filter_outpu;t = 0:1/fs:1-1/fs;figure(5plot(t,X_ttitle('窄带

4、信号在时域的波形'xlabel('t / s'grid on%莱斯表示法h_X = hilbert(X_t,Nfft ;%希尔伯特变换omega0 = 2*pi*f0;A_t = X_t.*cos(omega0*t+h_X.*sin(omega0*t;B_t = -1*X_t.*sin(omega0*t+h_X.*cos(omega0*t; figure(6subplot(2,1,1;plot(t,A_tgrid onhold onsubplot(2,1,2;plot(t,B_tgrid on%瞬时频率瞬时相位theta_t = atan(h_X./X_t; xh1=unwrap(angle(h_X; omega_t=fs*diff(xh1/(2*pi; figure(7plot(omega_t;title('瞬时频率'omega_t = diff(theta_t; figure(8plot(t,theta_ttitle('瞬时相位'grid on%包络检测am = abs(h