lmf4xx.m

这是有关锁相环的一些必用知识.希望能对大家有所帮助哈

for nn=1:1
clear

fs=50E+6;%采样频率
ts=1/fs;%采样时间间隔
k=15E+10;  %调频斜率
fo=10E+6;%载频
T=40E-6;%脉冲宽度
B=k*T;
n=4500;%抽样点数
t=ts:ts:n*ts;

p=zeros(1,n);
p(800+1:800+T*fs)=ones(1,T*fs);
signal=1/sqrt(T)*cos(2*pi*(fo*t+k*t.^2/2)).*p;
%signal=1/sqrt(T)*exp(j*2*pi*(fo*t+k*t.^2/2)).*p;
signal_spect=abs(fft(signal));

figure
subplot(2,1,1)
plot(signal)
subplot(2,1,2)
plot(signal_spect)

signal_power=sum(abs(signal).^2);
snr=-10;
noise_power=signal_power*10^(-snr/10);
a=sqrt(noise_power/n);
%a=0;
noise=a*randn(1,n);

s=signal+noise;
s_spect=abs(fft(s));

figure
subplot(2,1,1)
plot(s)
subplot(2,1,2)
plot(s_spect)

m2=50;
for i=-m2:m2
    s_cum(:,i+m2+1)=cum4est(s,100,1000,60,'unbiased',i,i);
end

s_cum_spect=abs(fft(s_cum));
figure
subplot(2,1,1)
mesh(s_cum)
subplot(2,1,2)
mesh(s_cum_spect)

signal_spect=abs(fft(signal));
for i=-m2:m2
    signal_cum(:,i+m2+1)=cum4est(signal,100,1000,60,'unbiased',i,i);
end

signal_cum_spect=abs(fft(signal_cum));
figure
subplot(2,1,1)
mesh(signal_cum)
subplot(2,1,2)
mesh(signal_cum_spect)

noise_spect=abs(fft(noise));
for i=-m2:m2
    noise_cum(:,i+m2+1)=cum4est(noise,100,1000,60,'unbiased',i,i);
end

noise_cum_spect=abs(fft(noise_cum));
figure
subplot(2,1,1)
mesh(noise_cum)
subplot(2,1,2)
mesh(noise_cum_spect)

end