costas.m

costas的matlab代码

% The goal of this simulation is to simulate carrier tracking loop with the
% way of costas loop.
clear all;
clc;
%------------simulate costas loop-------------
% disp(' ');
fdel = 30;          %input('Enter the size of frequency step in Hertz>');%
fn = 50.7143;       %input('Enter  loop filter natural frequency in Hertz>');%10
lambda = 0.01;      %input('Enter lambda, the relative pole offset>');%0.1
zeta = 1/sqrt(2);
%------采样频率------------------
fs = 4000*1.023;
tstop = 18;          %----结束时间----
npts = fs * tstop + 1;
t = (0:(npts-1))/fs;
nsettle = fix(npts/10);
tsettle = nsettle/fs;
freq = fs;
fin = [zeros(1, nsettle), fdel * ones(1,npts-nsettle)];    %--输入的频率
phin = [zeros(1, nsettle), 2*pi*fdel*t(1:npts-nsettle)];
PRN_num = 1023;%
        PRN_temp = double(0: (1/(sampleTimes*PRN_Fs)) :PRN_num*(1/(PRN_Fs)));
        PRN_t = PRN_temp(1:(length(PRN_temp)-1));
%        %--------------------------GPS PRN signal---------------------------
%------------------------carrier signal-----------------------------
%        %Fs = 4000;   t = 0:1/Fs:1;
%        Carrier_sample_time = PRN_t;
%        Carrier = cos(2 * pi * (Carrier_Frequency + Carrier_doppleFre_Shift)...
%                         * Carrier_sample_time + Phase_Diff); 
%        %-----plot--
%        figure;
%        an=[1:21];
%        stem(an.*(1/(sampleTimes*PRN_Fs)),Carrier(1:21));
%        hold on; 
%        plot(an.*(1/(sampleTimes*PRN_Fs)),Carrier(1:21),'r');
%        grid on;
%        if (sampleTimes*1000000/Carrier_Frequency>2)
%             title('Carrier Signal Over Sampling Rate');
%        else
%            title('Carrier Signal UnderSampling Rate');
%        end;