How to calculate time delay estimation?

[nateduong]

I have 2 data file
TX data file:

https://www.dropbox.com/s/xgyo6le3bcmd25r/RX.dat?d...

RX data file:

https://www.dropbox.com/s/0nmhw6mpgh7upmv/TX.dat?d...

and easily compute the delay from this code:

clear all; close all; format long;

%% initial values:
nsamps          = inf;
nstart          = 0;
Fs              = 8e6; % sample rate
flag            = 1;   % plot in the for loop
c               = 3e8; % speed of light

%% input data
file_tx         = 'TX.dat';
file_rx         = 'RX.dat';
x_tx            = readcplx(file_tx, nsamps,nstart); 
x_rx            = readcplx(file_rx, nsamps,nstart); 
data_time       = 10; % second % we can set time base on the length of vector x_rx
data_time       = floor((length(x_rx) - 8e5)/Fs) * 10;

factor          = data_time/10;
matric          = reshape(x_rx, [Fs/data_time*factor, data_time + 1]); 
matric          = matric';
size_of         = size(matric);
len             = 1:size_of(1);
delay           = zeros(1, data_time + 1);

%% time delay calculation:
aa      = zeros(1, length(matric(1,:)) - length(x_tx));
signal1 = [x_tx aa];    

for i = 1: 1%size_of(1)
    
    signal2                 = matric(i,:);
    [cc_correlation,lag]    = xcorr(signal1, signal2);
    [cc_maximum, cc_time]   = max(abs(cc_correlation));
    cc_estimation           = abs(length(signal1) - cc_time);
    delay(i)                = cc_estimation/Fs; % in second
    
    lagDiff                 = lag(cc_time);
    s2                      = signal2(abs(lagDiff)+1:end);
    t2                      = (0:length(s2)-1)/Fs;    
end
%%
fprintf('\n Done! \n\n');

function x = readcplx(filename,nsamps,nstart);
fid = fopen(filename);
fseek(fid,4 * nstart,'bof');
y = fread(fid,[2,inf],'short');
fclose(fid);
x = complex(y(1,:),y(2,:));

So I have matrix of delay:


delay = 0.010346125000000 0.010349000000000 0.0103498750000000.010349000000000 0.010349750000000 0.010349750000000 0.010349750000000 0.010349750000000 0.010348875000000 0.010348875000000 0.010348875000000

I want to make sure I did right or wrong?

Also, when I compute the xcorr, I see it weird from the plot, so I can not define the max of the yaxis. Do you see anything wrong?



I hope everyone can help me out?

Thank you very much.

 

[CCNezin]

The links to the data you provided don't seem to be full. Could you post the whole thing?