GPS Acquisition IF frequency in graph

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Rohit Mallampati 2020-4-13

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https://ww2.mathworks.cn/matlabcentral/answers/517465-gps-acquisition-if-frequency-in-graph

编辑： Mehmed Saad 2020-4-13

test1.jpg

I am trying to generate GPS Acquisition signals using frequency code phase search acquisition.

I generated C/A gold codes and digitised at 16.368e6 MHz(sampling frequency)
I generated carrier signals using exponential function at sampling frequency
I have input data with IF of 4.092e6 and sampling frequency as mentioned above. my inout data has 163680 samples
I multiplied input data with carrier signals which produces 1023 samples by considering 1023 samples from input data and converted into Fourier transform using FFT
I converted gold codes into frequency domain using FFT
I multiplied gold codes with step 4 to get final output with 1023 samples.

I have converted to absolute values and ploted. Then I got graphs as below. How to plot so that I can get IF in middle of graphs and how to plot correctly?

final_out is output from step 6:

[amp crw] = max(max(abs(final_out')));

[amp ccn] = max(max(abs(final_out)));

figure;

plot(abs(final_out(ccn,1:1023)));