xinhao.asv

基于chirp信号和Multitone信号的频率特性测试方法研究

close all; 
clear all;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%系统离散化及初始值设置%%%%%%%%%%%%%%%%%%%%%%%%%%%
Fs=2048;%采样频率
N1=2048;%采样点数
N=2048;
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=0.8;%频率F1信号的幅度
A0=10;
f0=1;%起始频率(Hz)
df=10;%频率间隔
f1=100;%结束频率
S=0;
M=round((f1-f0)/df)+1;
for i=1:M
   % ee(i)=i*(i-1)*pi/M;
end;
ee=2*pi*rand(1,M);
w=1;
for i=1:M
f=f0+df*(i-1);
S=A*sin(2*pi*f*t1+ee(w))+S;  %组合正弦波
%S=A*sin(2*pi*f*t1+0)+S;  %组合正弦波
w=w+1; 
end;
%S=S+rand(1,N1+1);
x=8*chirp(t1,1,N/Fs,700);%chirp
for i=N1:N+1 %补零消除栅栏效应
    S(i)=0;
    x(i)=0;
end;
[A,P,A1,P1,A0,P0,y]=qiuzhi(S,N,num,den);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%基本绘图%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
figure(1)
plot(t,S');
xlabel('t/s');
ylabel('辐值/v');
%grid;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%FFT绘图%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
figure(2)
pr=1;
for i=1:200
    if A1(i)>0.1
        AA(pr)=A1(i);
        ff(pr)=F(i);
         pr=pr+1;
    end; 
end;
w=ff;
stem(w,AA);
xlabel('f/Hz');
ylabel('辐值/v');
axis([0 102 0 1]);
%grid;