wpq.m

基于chirp信号和Multitone信号的频率特性测试方法研究

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%%%%%   组合正弦波和chirp法测频率特性MATLAB仿真    %%%%%%%%%
%%%%%%     虚拟仪器频率特性测试方法仿真            %%%%%%%%
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close all; 
clear all;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%系统离散化及初始值设置%%%%%%%%%%%%%%%%%%%%%%%%%%%
Fs=1000;%采样频率
N1=1000;%采样点数
N=1000;
dfs=Fs/N;%频率分辨率
t1=[0:1/Fs:N1/Fs]; %采样时刻
t=[0:1/Fs:N/Fs]; 
F=([1:N]-1)*Fs/N; %换算成实际的频率值
F=F(1:N/2);%取N/2个实际频率点
%sys=tf([-5],[2.0e-5 2e-9 1]);
sys=tf([3.355e7],[1 1.504e3 5.394e5 3.291e7]);
sysd=c2d(sys,1/Fs,'tustin');
[num,den]=tfdata(sysd,'v');
[h0,f0]=freqz(num,den,N/2,Fs);
mag=abs(h0);
ph=angle(h0);
ph=ph*180/pi;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%输入信号%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
A=0.5;%频率F1信号的幅度
A0=10;
f0=1;%起始频率(Hz)
df=1;%频率间隔
f1=30;%结束频率
S=0;
x1=8*chirp(t1,1,N/Fs,60);%chirp
for i=1:N
x2(i)=8*sin(2*pi*(f0+(f1-f0)*i/N)*i/Fs);
end;
for i=N1:N+1 %补零消除栅栏效应
    S(i)=0;
    x(i)=0;
end;
[Ax,Px,A1x,P1x,A0x,P0x,y1]=qiuzhi(x1,N,num,den);
[Axf,Pxf,A1xf,P1xf,A0xf,P0xf,y1f]=qiuzhi(x2,N,num,den);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%基本绘图%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
figure(1)
plot(t,x1,'r');
legend('组合正弦波');
grid;
title('输入信号');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%FFT绘图%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
figure(2)
plot(F,A1x,'r',F,A1xf,'b');
legend('chirp');
grid;%显示换算后的FFT模值结果
title('输入信号幅度-频率曲线图');
axis([0 200 -2 2]);