How to increase the resolution of the ambiguity function when I need to apply the sampling frequency (Fs) greater than 10 to the power of 6?

I would like to obtain the time delay and Doppler shift between two received signals by using afmag = ambgfun(x,y,Fs,PRF).

where x and y are the two received signals, Fs is the sampling frequency and PRF is the pulse repetition frequency.

It works well if I apply up to 10^6 for Fs but Matlab cannot perform beyond 10^6 of Fs.

Does anyone know how I can improve the resolution of the ambiguity function such as interpolation or something when I

cannot apply Fs greater than 10^6?

Thanks you for your comments.

Answer 1

[Yukthi S]

Hi John

I got that the Ambiguity function was performing well till Fs<10^6 and you wanted to improve the resolution of the function when you can not apply Fs>10^6.

Here ,I am going to use the function “interp2”.Interpolation can enhance visual representation,but it does not increase the actual information content of your data.

You can refer to the following code on how to use the “interp2” function and make changes accordingly.

afmag = ambgfun(x, y, Fs, PRF);
% Define the interpolation factor, e.g., to interpolate by a factor of 10
interp_factor = 10;
% Create a grid for the original ambiguity function dimensions
[rows, cols] = size(afmag);
row_grid = 1:rows;
col_grid = 1:cols;
% Create a finer grid for interpolation
fine_row_grid = linspace(1, rows, rows * interp_factor);
fine_col_grid = linspace(1, cols, cols * interp_factor);
% Perform 2D interpolation
afmag_interp = interp2(row_grid, col_grid, afmag, fine_row_grid', fine_col_grid, 'spline');

You can refer to the below link to understand “interp2” more clearly:https://www.mathworks.com/help/releases/R2021b/matlab/ref/interp2.html?s_tid=doc_ta#btyq8s0-3:~:text=Product%20Updates-,interp2,-Interpolation%20for%202

You can also have a look at the below link for more information on Interpolation methods:https://www.mathworks.com/help/releases/R2021b/matlab/ref/interp2.html?s_tid=doc_ta#btyq8s0-3:~:text=method%20%E2%80%94%20Interpolation%20method