Adaptive beamformer

About: Adaptive beamformer is a research topic. Over the lifetime, 4934 publications have been published within this topic receiving 93100 citations.

Adaptive mode control apparatus and method for adaptive beamforming based on detection of user direction sound

Abstract: An adaptive mode control apparatus and method for adaptive beamforming based on detection of a user direction sound are provided. The adaptive mode control apparatus includes a signal intensity detector that searches for signal intensity of each designated direction to detect signal intensity having a maximum value when a voice signal of each direction is input through at least one microphone; and an adaptive mode controller that compares the signal intensity having the maximum value detected through the signal intensity detector with a threshold value and determines whether to perform an adaptive mode of a Generalized Sidelobe Canceller (GSC) according to the comparison results. Therefore, a lack of control of adaptation of an adaptive filter of the conventional art is solved. That is, as one condition for guaranteeing performance of adaptive beamforming, adaptation of an adaptive filter is not performed when noise of a sound with a high autocorrelation is cancelled.

Robust adaptive beamforming based on the Kalman filter

Abstract: In this paper, we present a novel approach to implement the robust minimum variance distortionless response (MVDR) beamformer. This beamformer is based on worst-case performance optimization and has been shown to provide an excellent robustness against arbitrary but norm-bounded mismatches in the desired signal steering vector. However, the existing algorithms to solve this problem do not have direct computationally efficient online implementations. In this paper, we develop a new algorithm for the robust MVDR beamformer, which is based on the constrained Kalman filter and can be implemented online with a low computational cost. Our algorithm is shown to have a similar performance to that of the original second-order cone programming (SOCP)-based implementation of the robust MVDR beamformer. We also present two improved modifications of the proposed algorithm to additionally account for nonstationary environments. These modifications are based on model switching and hypothesis merging techniques that further improve the robustness of the beamformer against rapid (abrupt) environmental changes.

Method and apparatus for adaptively reducing the level of noise in an acquired signal

Abstract: An adaptive filtering method and apparatus for reducing the level of an undesired noise component in an acquired physiological signal having a desired signal component. The acquired physiological signal is applied to one input of the adaptive filter, and a synthetic reference signal that is modeled so as to exhibit a correlation with the desired signal component is applied to another input of the adaptive filter. Thereafter, in a feedback manner, the adaptive filter iteratively adjusts the modeled synthetic reference signal so as to progressively generate a more accurate approximation of the desired signal component in the adaptive filter, which approximation becomes a reconstruction of the acquired physiological signal wherein the level of the undesired noise component is reduced.

Multiple antenna multicarrier transmitter and method for adaptive beamforming with transmit-power normalization

Abstract: In a multi-antenna, multicarrier transmitter, a multicarrier communication signal is generated by normalizing beamforming matrices based on an average subcarrier power loading for each of the transmit antennas. One or more spatial streams may be transmitted by two or more antennas.

Navigation accuracy and interference rejection for GPS adaptive antenna arrays

Abstract: In the Joint Precision Approach and Landing System (JPALS) both the differential GPS reference station and the airborne user will employ Controlled Reception Pattern Array (CRPA) antennas In a high precision system such as JPALS, CRPA antennas may suffer phase center biases that introduce significant integrity risk These phase center biases result from both hardware design and from algorithm selection (beamsteering and/or nullforming) This study shows that there is a clear tradeoff between radio frequency interference (RFI) rejection and the introduction of biases in the pseudorange and carrier-phase navigation outputs from a space-time adaptive processor (STAP) GPS receiver Deterministic corrections based either on single-element or array calibration (and implemented as a line-of-sight-based lookup table) will reduce pseudorange and carrier-phase biases in the tracking output For the STAP algorithms and patch-element-based antenna array considered here, the carrier-phase bias residuals are on the order of 0-10° and the pseudorange bias residuals are in the 10’s of cm While the carrier-phase residuals are likely tolerable for high-integrity carrier-phase-differential integer resolution, the code-phase residuals are troubling and will need further work in regards either to algorithm development, to antenna design improvements, or to both