FM signal, modulated signal and carrier

1、 Content abstract

A little
353- Can communicate 、 consulting 、 Answering question

2、 Content description

A little

3、 Simulation analysis

% The modulated signal is FM The signal , The FM signal is composed of 1KHz Modulated signal and 10kHz Of the carrier wave 
clear all;            % initialization 
clc;
close all;
f=5000;               % Carrier frequency   5KHz
fs=1000000;            % sampling frequency 
N=5000;               % Number of sampling points             
Ts=1/fs;                % Sampling period 
t=(0:Ts:(N-1)*Ts);       % Simulation time 
f1=500;               % Modulation signal frequency   500Hz
msg=sin(2*pi*f1*t);               % Modulation signal 
figure,plot(msg);
figure,plot(cumsum(msg));
kf=0.0716;                       % Frequency modulation sensitivity 
Signal1=exp(j*(2*pi*f*t));          % carrier 
Signal=exp(j*(2*pi*f*t+2*pi*kf*cumsum(msg))); 
figure,plot(imag(Signal1));
figure,plot(real(Signal1));
% Modulated signal ,FM The signal ,cumsum Is an accumulation function ;

phi_hat(1)=10;        % Modulated signal （ PLL ） Enter the initial value  10
e(1)=0;               % Initial value of frequency difference 
phd_output(1)=0;      % Demodulated signal output initial value 
vco(1)=0;             % VCO output initial value 
kp=0.125;              % Loop filter parameters 
ki=0.125;               % Loop filter parameters 

% PLL 


startplot=1;                % Drawing start position 
endplot=2000;              % Drawing end position 


figure(1);                  % At the window 1 mapping 
subplot(2,2,2);              % Multiple drawings are drawn on one plane 
plot(t(startplot:endplot),msg(startplot:endplot));         % Plot function , The abscissa is time t
title(' Modulation signal （ frequency 1KHz）');                     % Icon title 
xlabel(' Time （seconds）');                          % Abscissa annotation 
ylabel(' Range ');                                     % Ordinate annotation 
grid;
figure(1);
subplot(2,2,1);
plot(t(startplot:endplot),real(Signal1(startplot:endplot)));
title(' carrier ');
ylabel(' Range ');
grid;

figure(1);
subplot(2,2,3);
plot(t(startplot:endplot),real(Signal(startplot:endplot)));
title('FM Modulated signal ');
ylabel(' Range ');
grid;


figure(1);
subplot(2,2,4);
plot(t(startplot:endplot),e(startplot:endplot));
title(' Demodulate the signal ');
ylabel(' Range ');
grid;

[f_Signal,y_Signal]=change_fft(fs,Signal);
[f_msg,y_msg]=change_fft(fs,msg);
[f_e,y_e]=change_fft(fs,e);
figure
plot(f_Signal,y_Signal)
xlabel  frequency /Hz
ylabel  amplitude 
title Signal
xlim([0 100000])
figure
plot(f_msg,y_msg)
xlabel  frequency /Hz
ylabel  amplitude 
title msg
xlim([0 5000])
figure
plot(f_e,y_e)
xlabel  frequency /Hz
ylabel  amplitude 
title e
xlim([0 5000])

[f_Signal_imag,y_Signal_imag]=change_fft(fs,imag(Signal));
figure
plot(f_Signal_imag,y_Signal_imag)
xlabel  frequency /Hz
ylabel  amplitude 
title Signal Imaginary part 
xlim([0 100000])

 

 

 

 

4、 Reference paper

A little