MATLAB: Directivity pattern for a beamformed signal

directivity patterndsbmircophone array;Phased Array System Toolbox

Finally, I got a signal y(1×5001) (delayed and summed output of the microphones).

How can I plot the directivity pattern(mesh-plot) of the above array? I have gone through many books which describe the pattern mostly for linear array geometries. If Iam not wrong, I should end up having my mainlobe at (30°,45°) for my wideband output signal 'y' (that would mean my beamformer is working).

How can I go about doing this using the signal y? What would be the steering vector in my case?

Please help.

Best Answer

In many literature, beam pattern is a narrow band concept so it is related to the steering vector. Since you are using time domain beamforming, I would do the following:

1. Simulate incoming signals for each direction you would like to calculate the beam pattern. It is the same as you simulate your source.

2. Process each signal using the SAME beamformer you use for your desired source, i.e., beamform each signal to (30, 45) degrees.

3. Now you get a beamformed signal for each direction and you can now compute the power or energy for those signals. You can then plot power or energy as a function of angle and it should match your beam pattern.

HTH

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MATLAB: Time Delay of Arrival of two acoustic signals from an array using Phased Toolbox

The default frqeuency range for the hydrophone is between 0 and 200 kHz. However, in your example, the carrier is set at 300 kHz, so the response is not correctly generated. If you replace the hydrophone definition as

hydrophone = phased.IsotropicHydrophone('VoltageSensitivity',-150,'FrequencyRange',[0 1e6]);

Then it works fine.

HTH

MATLAB: Delay and sum beamforming(in frequency domain)

Hi Zoro,

What you have so far is calculating the delays between the elements. The next steps will be

(1) simulate the received signal at each element. Here you need to use the delay you just calculated to delay the signal at each element accordingly.

(2) You can then use delay and sum beamformer to align the received together and see the combined signal.

(1) and (2) are essentially inverse operations. Because you are dealing with microphone signals, the signal by nature is wideband. So there are two ways you can do it, either you do the delay-and-sum in the time domain or you have to break the signal into narrowbands, do the delay-and-sum in frequency domain at each band and then combine result at each narrowband together to get the final result.

Best Answer

Related Solutions

MATLAB: Time Delay of Arrival of two acoustic signals from an array using Phased Toolbox

MATLAB: Delay and sum beamforming(in frequency domain)

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