cw_noise.m

产生带限白噪声

%   本函数实现n通道noch滤波器组

clc;
close all;
clear all;

%%%%%%%%%%%%%%%%%%%%%%%%%%  initialize variable%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Fre_Low=12000;                          %滤波器组的起始中心频率
Fre_Deta=2000;                          %各组滤波器的中心频率差值
sig_f0=12000;                           %输入CW脉冲的填充频率
sig_f1=12600;
fs=100000;

sig_A=1;
snr=30;
sig_len=2*fs/1000;                     %2ms
noi1_len=1*fs/1000;
noi2_len=1*fs/1000;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
nsr=sig_A/(sqrt(2)*(10.^(snr/20)));
%%%%%%%%%%%%%%%%%%%%%%%%generate signal %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
wnl=7000;
wnh=25000;                              %带限噪声的上下限频率
i=1:sig_len;
sig1=sig_A*sin(2*pi*i*sig_f0/fs);
sig2=sig_A*sin(2*pi*i*sig_f1/fs);
noi1=nsr*noise(wnl,wnh,fs,noi1_len,0);
noi2=nsr*noise(wnl,wnh,fs,noi2_len,0);
noi_s=nsr*noise(wnl,wnh,fs,sig_len,0);
mydata1=[noi1 sig1+noi_s  noi2];          %带噪CW脉冲由三段点数相同的noi1、sig+noi_s与noi2组成
mydata2=[noi1 sig2+noi_s  noi2]; 
fft_mydata1=abs(fft(mydata1,fs));
fft_mydata2=abs(fft(mydata2,fs));
figure;
subplot(121)
plot(mydata1);
xlabel('n');ylabel('幅度');title('  CW脉冲时域波形');
subplot(122)
%plot(10*log10(fft_mydata(1:length(fft_mydata)/2))); 
% plot(fft_mydata(1:length(fft_mydata)/2)); 
plot((10500:13500 ),fft_mydata1(10500:13500),(11100:14100),fft_mydata2(11100:14100),'k:');
% plot((11000:13000 ),fft_mydata1(11000:13000),(11600:13600),fft_mydata2(11600:13600),'g');

xlabel('f');ylabel('幅度');title('  CW脉冲频域波形(截取)');