MATLAB: Findpeaks outputs random values for distant targets!!

antennacommunicationsfindpeaksfmcwfrequencyphased arrayPhased Array System Toolboxradartransmitter

I am working on Frequency Modulated Continuous Wave (FMCW) radar which linearly modulate frequency according to the amplitude of a sawtooth. My model is capable of detecting target ranging from 0.5m to 300m. The signal processor block is coded to provide 4 maximum peaks through 'findpeaks' and thereby 2 targets placed at different distances. Technically it should give me two peaks at respective frequencies and thus calculating distances. function but when I set one target at 1m and the other at 299m it gives accurate distance for 1m target but not for 299m object. Scenario 2 : 1st target 250m and second target 299m, it gives accurate results for both targets. I think my code is correct but I cannot isolate the problem. Help is appreciated , attached is my model and the code.

Best Answer

Haven't got chance to run your model. But what is the wrong value it reports when the target at 299m is not detected? Is it very close to 1 m? If so, this may due to the return of the 1m target much stronger than that of the 299m target, so you are essentially getting the sidelobe of the first target.

HTH

Related Solutions

MATLAB: Can you limit findpeaks to only look for odd peaks (i.e. search 1st, 3d, 5th, etc. peaks)

No. You just find them all and subsample

[peakValues, indexesOfPeaks] = findpeaks(signals);
peakValues = peakValues(1:2:end);
indexesOfPeaks = indexesOfPeaks(1:2:end);

MATLAB: Directivity did not match our expectation

Hi Ralph,

In this example you are using an isotropic antenna element. So even though in this cut the beam is more focused, it has strong lobe all around the array axis, so in some sense the energy is not well focused.

If we change the element type to a more realistic pattern, such as cosine antenna pattern, then you can see the directivity of the ULA starts to be better than the URA

figure
ha = phased.ULA('NumElements',16,'Element',phased.CosineAntennaElement);
plotResponse(ha,3e8,3e8,'RespCut','Az','Format','Polar','Unit','dbi');
hold on;
ha = phased.URA('Size',[4 4],'Element',phased.CosineAntennaElement);
plotResponse(ha,3e8,3e8,'RespCut','Az','Format','Polar','Unit','dbi');

If you use a Hertzian dipole, the ULA is also better

figure
ha = phased.ULA('NumElements',16,'Element',phased.ShortDipoleAntennaElement);
plotResponse(ha,3e8,3e8,'RespCut','Az','Format','Polar','Unit','dbi');
hold on;
ha = phased.URA('Size',[4 4],'Element',phased.ShortDipoleAntennaElement);
plotResponse(ha,3e8,3e8,'RespCut','Az','Format','Polar','Unit','dbi');

In short, I'm not saying that you are wrong since I don't really have a theoretical result to back me up. But I'm also not convinced that the toolbox is giving the wrong answer. If you do have a number that I can compare to, please let me know and I'd love to take a look.

Thanks

Best Answer

Related Solutions

MATLAB: Can you limit findpeaks to only look for odd peaks (i.e. search 1st, 3d, 5th, etc. peaks)

MATLAB: Directivity did not match our expectation

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