锁相环的MATLAB的仿真程序.doc

%%Phasell.m %The phase locked loop(PLL),adjusts the phase of a local oscillator %w.r.t the incoming modulated signal.In this way,the phase of the %incoming signal is locked and the signal is demodulated.This scheme %is used in PM and FM as well. %We will implement it by using a closed loop system.Control systems %techniques are applied here. %************************************************************** %STEP RESPONSE OF THE FIRST ORDER CLOSED LOOP TRANSMITTANCE OF PLL %H(S) = 1; %SYSTEM TYPE NUMBER = 1; %THETAo/THETAi (output phase/input phase) close all kv = 1; kd = 1; dt = 0.01 t = 0:dt:2 u = ones(1,length(t)) g11 = [tf([2*pi*kv*kd],[1 2*pi*kv*kd])] %its the transfer function given in the handout [y11 t] = lsim(g11,u,t) figure plot(t,y11) xlabel(TIME IN SECONDS) ylabel(AMPLITUDE) title(STEP RESPONSE OF 1st ORDER CLOSED LOOP TRANSMITTANCE) %*************************************************************** %STEP RESPONSE OF THE FIRST ORDER CLOSED LOOP ERROR TRANSMITTANCE OF PLL %ALL THE OTHER FACTORS H(S) etc ARE SAME HERE %THETAe/THETAi (same interp. as above) g12 = [tf([1 0],[1 2*pi*kv*kd])] %error transmittance given in the handout [y12 t] = lsim(g12,u,t) figure plot(t,y12) xlabel(TIME IN SECONDS) ylabel(AMPLITUDE) title(STEP RESPONSE OF 1st ORDER CLOSED LOOP ERROR TRANSMITTANCE) %**************************************************************** %STEP RESPONSE OF THE FIRST ORDER CLOSED LOOP TRANSMITTANCE OF PLL %BETWEEN VCO AND INPUT SIGNAL PHASE %H(S) = 1; %SYSTEM TYPE NUMBER = 1; %V2/THETAi Kd =1; g13 = [tf([Kd 0],[1 2*pi*kv*kd])] %vco voltage and input signal transmittance [y13 t] = lsim(g13,u,t) figure plot(t,y13) xlabel(TIME IN SECONDS) ylabel(AMPLITUDE) title(STEP RESPONSE OF 1st ORDER CLOSED LOOP TRANSMITTANCE B/W VCO AND INPUT PHASE) %******************************************************************** %STEP RESPONSE OF THE SECOND ORDER CLOSED LOOP TRANSMITTANCE OF PLL %SYSTEM TYPE