How to set the received signal in DoA algorithm?

Hello everyone,

I am trying to localize the direction of Arrival of my imported Signal using MUSIC algorithm. The size of my Signal (X) is 18182*32 which 32 is the number of the microphones. I use this Syntax to define my Signal: Y = collectPlaneWave(H,X,ANG,FREQ,C). Here I have attached the code and the error as well. The erros says somthing about a Zero value in my Signal which I could not get rid of. I would be grateful to get any help or comments from you.

The error is:

Error using coder.internal.errorIf (line 8)
The AIC algorithm is not applicable when one of the eigenvalues of signal covariance matrix is zero.
Error in phased.internal.aictest (line 22)
       coder.internal.errorIf(any(eigenvals==0), ...
Error in phased.MUSICEstimator2D/getNumSignals (line 267)
                D = phased.internal.aictest(eigenvals,K,fb);
Error in phased.MUSICEstimator2D/privDOASpectrum (line 224)
        Nsig = getNumSignals(obj,eigenvals,obj.pNumSnapshots,fb);
Error in phased.MUSICEstimator2D/stepImpl (line 155)
    numSignals = privDOASpectrum(obj,X);
Error in DOA32 (line 39)
[ang] = step(hDoA,x);

You need Phased Array System Toolbox to run the code.

Regards

[Ali Movahed]

Size of the Signal is 1000*32.

Answer 1

[Honglei Chen]

Looks like you didn't add any noise so the AIC errors out. You can just add some noise, like

Y = Y + sqrt(npow/2)*(randn(size(Y))+1i*randn(size(Y)))

where npow is the noise power.

HTH

[Ali Movahed]

Thank you so much. How should I set this noise when I Import the real Signal recorded by a microphone Array? Regards

[Ali Movahed]

and How can I Change the 'ANG' when there are two sources with different azimuth and Elevation angles? Thank you.

[Honglei Chen]

The noise level is your choice.

[Honglei Chen]

For different azimuth and elevation angles, you just need to use ang to represent two directions. For example

ang = [10 20;0 30]

means one source is from 10 degrees azimuth and 0 degrees elevation, while the other one is from 20 degrees azimuth and 30 degrees elevation.

[Ali Movahed]

Thank you for your response. I get an error when set the angles to what you said. Error: Error using coder.internal.errorIf (line 8) Expected ANGLE to be of size either 1x32 or 2x32 when it is actually size 2x2.

Error in phased.internal.AbstractArray/collectPlaneWave (line 445) coder.internal.errorIf(cond,'phased:collectPlaneWave:incorrectSize', ...

Error in DOA32 (line 26) x=collectPlaneWave(h,recon,ang,fc,c); I guess I have to include the number of microphones in the size of angles. It has to be probably 1*32 or 2*32. Regards

[Honglei Chen]

Sorry I didn't look at your script carefully. In your script, you have this line

x=collectPlaneWave(h,randn(1000,32),ang,100e3,c);

This means there are 32 signals impinging on your array. I'm actually not sure what you mean here, it seems to me that you are thinking this is the signal on the array where each column is the signal on a specific element? I assume this is why you make all the ang to represent 32 same angles? If that's the case, it is not how collectPlaneWave works. If actually considers each column in the input as a separate signal. Thus, if I want to model two independent signals, I would do

x=collectPlaneWave(h,randn(1000,2),[10 20;20 0],100e3,c);

The output on the other hand would be 32 columns to reflect that this is the signal collected on a 32-element array. And the output signal will contain both signal specified in the function call.

Does that clarify things? Please let me know if I understand the problem wrong.