Overview

Frequency domain based beamformer

Discussion

This module implements a frequency domain based beamformer. The module has a multichannel input pin "in" which correspond to N microphone signals. The microphone signals must already be in the frequency domain (e.g., after an FFT or WOLA filterbank). The module has an internal table of complex filter coefficients of size [numMics, numBins]. The module multiples each microphone signal by complex coefficients and then sums across all microphone channels. This corresponds to filtering each microphone signal and summing the results.

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The coefficients are ordered as follows. The first 2 * numBins * numMics coefficients correspond to the first beamformer. The coefficient are ordered first based on input channel and then on frequency bin. The coefficient are interleaved real / imag values. The beamformer coefficients can be loaded using the function sb_beamformer_config.m

Type Definition

typedef struct _ModuleSbBeamformerV2
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 numBeams;                               // Number of beams allocated.
    INT32 numCoeffs;                              // Number of coefficients to allocate
    INT32 numBins;                                // Number of bins this beamformer is calculating on
    FLOAT32* coeffs;                              // Complex beamformer coefficients.
    FLOAT32* noiseGain;                           // Beamformer noise gain - real numbers.
} ModuleSbBeamformerV2Class;

Variables

Properties

Pins

Input Pins

Name: index

Description: Selects beam

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Sample rate range: Unrestricted

Complex support: Complex

Output Pins

Name: out

Description: Beam output

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Description: Noise Gain of this Beamformer

Data type: float

MATLAB Usage

File Name: sb_beamformer_v2_module.m

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