how to write a m file code to cfar for fmcw radar

how to write a m file code to cfar for fmcw radar can anyone help plz

Answer 1

[Abdullah OZCAN]

CFAR thresholding does not depend on the radar type. It is about thresholding the signal at the mixer output. The signal is the amplitude level of range measurements. Here is a sample code. It is only about finding the noise average. This code implements the cell averaging cfar:

close all;

s=randn(1000,1);

s([100, 300, 700])=[30 40 50];

figure,plot(s);

refLength=12;

guardLength=3;

offset=3;

cfarWin=ones((refLength+guardLength)*2+1,1);

cfarWin(refLength+1:refLength+1+2*guardLength)=0;

cfarWin=cfarWin/sum(cfarWin);

noiseLevel=conv(s,cfarWin,'same');

cfarThreshold=noiseLevel+offset;

figure,plot(s);

hold on,plot(cfarThreshold,'r--','LineWidth',2)

legend('Signal','CFAR Threshold')

[venu dunde]

thank you for your answer, how we can choose s([100, 300, 700])=[30 40 50]; , efLength=12; guardLength=3; offset=3; values. usually s is the noise alone, if the signal corrupted with noise how we can choose these values compare with the signal without noise. please give me the code.

[Kaitlyn Nguyen]

What about OS-CFAR? Do you have sample code for that?

Also how do you calculate the detection?

Thank you!

[Amr Aboughazala]

but why offset with addition?

This is different than the scale that have to be multiplied in linear domain. The scale should depend on the desired probability of false alarm.

N = refLength*2;
scale = pbFalseAlarm^(-1/N) - 1;
cfarThreshold=noiseLevel*scale;

is that correct?

Answer 2

[Honglei Chen]

You may also want to take a look at CFAR detector offered in Phased Array System Toolbox. The noise is estimated using training cells that does not include signal.

http://www.mathworks.com/help/phased/examples/constant-false-alarm-rate-cfar-detection.html