How to obtain the coordinate of the maximum value in the Cross ambiguity function

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John Lee 2021-2-19

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评论： John Lee 2021-2-19

I am trying to find delay and doppler shift between two received signals by using the cross ambiguity function as follows.

prf = [1/1e-3 1/1e-3];

Fs = 1/1e-5;

[afmag,dly,dpp] = ambgfun(r1,r2,Fs,prf); % two received signals: r1 and r2

So, I obtain 2D array of afmag besides dly and dpp.

I think the coordiate where afmag is the maximum is what I want.

I may be able to find afmag, but I am not sure how to find the corresponding "dly" and "dpp" at that point of "afmag".

So, I want to know the maximum value of "afmag", the values of "dly" and "dpp" at that maximum point.

Thank you for your help.

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Answer 1

David Goodmanson 2021-2-19

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Hi John,

Not having the phased array system toolbox I don't know how the plot axes are oriented, but I think one of the two possibilities below should work, assuming the basic idea is correct. You would have to check on a plot.

[afmag,dly,dpp] = ambgfun(r1,r2,Fs,prf);  % two received signals: r1 and r2
[~,k] = max(afmag(:))
[i j] = ind2sub(size(afmag),k)
% either this
   dly0 = dly(i)
   dpp0 = dpp(j)
% or this
   dly0 = dly(j)
   dpp0 = dpp(i)