Audio Beamforming Using Eigenbeams for Directivity and Noise Cancellation

The patent changes the fundamental parameters of the beamforming approach by using additive delay-and-sum beamforming with carefully designed time delays and phase shifts, rather than superdirective techniques. This parameter change allows achieving good directivity without the harmful sensitivity to noise and mismatches that characterizes superdirective beamforming.

The patent employs simple, robust delay-and-sum operations that are computationally inexpensive and numerically stable, rather than complex superdirective filters. This approach uses simpler processing that is less sensitive to implementation errors and environmental variations, effectively trading some theoretical directivity performance for robustness and reliability.

The patent introduces dynamic adaptability to the simple delay-and-sum framework by continuously estimating interference directions and updating beamforming weights in real-time. This dynamic adaptation allows the system to maintain good directivity performance even when the array is small compared to the wavelength, overcoming the static limitations of conventional delay-and-sum beamforming.

The patent implements feedback mechanisms where the output of the beamformer is used to estimate interference directions, which then feed back into updating the beamforming weights. This feedback loop enables the system to adaptively improve its directivity performance based on actual environmental conditions, compensating for the inherent limitations of small arrays.

The patent segments the beamforming process into distinct functional blocks: interference direction estimation, weight calculation, and signal combination. Each block performs a specific, relatively simple function, making the overall complex task manageable and efficient to implement. This segmentation allows using straightforward algorithms like power spectral density estimation and closed-form weight solutions rather than requiring complex iterative optimization.

The patent replaces complex mechanical or computational beamforming systems with an electronic signal processing approach using simple delay-and-sum operations combined with adaptive weighting. This substitution uses efficient digital signal processing techniques that require minimal computational resources compared to more complex beamforming algorithms, achieving good interference cancellation with low processing complexity.