Carrier Synchronization

Synchronization is amethods to generate sinusoids with the same frequency and phase of the carrier at the demodulator.

A carrier synchronization system consists of a local oscillator whose phase is controlled
to be in synch with the carrier signal. This is achieved by employing a PLL

Note, a simple first-order loop filter results in a PLL that can track jumps in the input phase.

Matlab Coding

 1 % MATLAB script for Illustrative Problem 7.13.
 2 echo on
 3 num=[0.01 1];
 4 den=[1 1.01 1];
 5 [a,b,c,d]=tf2ss(num,den);
 6 dt=0.01;
 7 u=ones(1,2000);
 8 x=zeros(2,2001);
 9 for i=1:2000
10     x(:,i+1)=x(:,i)+dt.*a*x(:,i)+dt.*b*u(i);
11     y(i)=c*x(:,i);
12     echo off;
13 end
14 echo on;
 
15 t=[0:dt:20];
16 plot(t(1:2000),y)

Simulation Result

Reference,

　　1.<<Contemporary Communication System using MATLAB>> -John G. Proakis