Beamforming with microphone arrays

Hello everyone, I have 16 microphones in my code trying to have the 2d Response pattern of the Sound source. The Position of the source is defined in the code and I suppose to get a 2d diagram which Shows the power of the source in dB. I run this code and get an error which is does nor make any sense to me. could you please give me your comments?

% Define my microphone array
h = phased.ConformalArray();
t= 1/2*(1+sqrt(5));
n=16;
c= ones(n,1)';
c(:)=1:16;
h.ElementPosition = [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0;(sqrt(c).*cos(2*pi*t*c))*0.0375;(sqrt(c).*sin(2*pi*t*c))*0.0375];
h.ElementNormal = [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0;0 0 0 0 0 ...
    0 0 0 0 0 0 0 0 0 0 0];
h.Element = ...
    phased.OmnidirectionalMicrophoneElement('BackBaffled',true,'FrequencyRange',[48e3 580e3]);
% Define my Signal
t = 0:0.001:0.3;                % Time, sampling frequency is 1kHz
s = zeros(size(t));
s = s(:);                       % Signal in column vector
s(201:205) = s(201:205) + 1;    % Define the pulse
carrierFreq = 100e6;
wavelength = physconst('LightSpeed')/carrierFreq;
inputAngle = [45; 0];
x = collectPlaneWave(h,s,inputAngle,carrierFreq);
% Define the MVDR beamformer
mvdrbeamformer = phased.MVDRBeamformer('SensorArray',h,...
    'Direction',inputAngle,'OperatingFrequency',carrierFreq,...
    'WeightsOutputPort',true);
% Pattern
pattern(h,carrierFreq,-180:180,0,'Weights',true,'Type','powerdb',...
    'PropagationSpeed',physconst('LightSpeed'),'Normalize',false,...
    'CoordinateSystem','rectangular');
axis([-90 90 -80 20]);

[Ali Movahed]

here is the Error: Undefined function 'pattern' for input arguments of type 'phased.ConformalArray'.

Error in Newbeamforming (line 26) pattern(h,carrierFreq,-180:180,0,'Weights',true,'Type','powerdb',...

[Nick Yiw]

Hi, I am a student currently working on a project that involves distance speech recognition for controlling output. I really want to know what are the best recommendations of microphone arrays/chips that I can use which are compatible with MATLAB. Thank you.

Answer 1

[Honglei Chen]

Looks like you are using an older version of the toolbox. Which release are you using? Instead of using

pattern(h,carrierFreq,-180:180,0,'Weights',true,'Type','powerdb',...
  'PropagationSpeed',physconst('LightSpeed'),'Normalize',false,...
  'CoordinateSystem','rectangular');
axis([-90 90- -80 20])

try

plotResponse(h,10e4,physconst('LightSpeed'),'Format','line',...
  'RespCut','az','Unit','db','NormalizeResponse',false);

and see if it works.

BTW, the argument following the 'weights' parameter should be a numerical vector containing the array weights instead of a logical. I'm not sure what you want to put in there so I ignored it. Also the frequency specified in pattern() is 100e6 yet the elements only work between 48 kHz and 580 kHz, so I used 100 kHz in my example.

HTH

[Ali Movahed]

thank you so much. your solution worked very well. When I want to set weights, I get another error. I add just one line to the same part which u changed.

[yCbf,w]= mvdrbeamformer(x);
pattern(h,carrierFreq,-180:180,0,'Weights',w,'Type','powerdb',...
  'PropagationSpeed',physconst('LightSpeed'),'Normalize',false,...
  'CoordinateSystem','rectangular');
axis([-90 90 -80 20]);

and I get this error: Array formation and parentheses-style indexing with objects of class 'phased.MVDRBeamformer' is not allowed. Use objects of class 'phased.MVDRBeamformer' only as scalars or use a cell array.

Error in Newbeamforming (line 25) [yCbf,w]= mvdrbeamformer(x); Thank you.

[Honglei Chen]

In your release, you would have to do

[yCbf,w] = step(mvdrbeamformer,x);

HTH

[Ali Movahed]

Hello, I have done that but again this error appears:

Warning: Matrix is singular to working precision. 
> In lcmvweights>qrlinsolve at 97
  In lcmvweights at 69
  In MVDRBeamformer>MVDRBeamformer.stepImpl at 243
  In Newbeamforming at 27 
Warning: Matrix is singular to working precision. 
> In lcmvweights>qrlinsolve at 98
  In lcmvweights at 69
  In MVDRBeamformer>MVDRBeamformer.stepImpl at 243
  In Newbeamforming at 27 
Undefined function 'pattern' for input arguments of type 'phased.ConformalArray'.

Error in Newbeamforming (line 28)
pattern(h,carrierFreq,-180:180,0,'Weights',w,'Type','powerdb',...

[Ali Movahed]

and could you please tell me with which function can I have the same result in 3D? somthing like plot Response 3D? Thank you.

[Honglei Chen]

The warning is indicates that the covariance matrix is not well constructed. I don't the dimension of x, but you may need more snapshots, i.e., more rows in that matrix.

The error is about pattern() so looks like you still have a call to pattern() in your script?

To plot 3D pattern, in the plotResponse() call, replace 'az', with '3d', like

plotResponse(h,10e4,physconst('LightSpeed'),'Format','line',...
  'RespCut','3d','Unit','db','NormalizeResponse',false);

[Ali Movahed]

Hello, actually the size of x is 301*16 and all the values are Zero. I think some how weights are not calculated in my code. could you please calculate the weights[yCbf,w] = step(mvdrbeamformer,x); in your code when using plotResponse not Pattern? thank you.