Adaptive beamformer
Encyclopedia
An adaptive beamformer is a beamforming
system which performs adaptive spatial signal processing
with an array of radar
antennas (or phased array
) in order to transmit or receive signals in different directions without having to mechanically steer the array.
The main distinction between an adaptive beamformer and a conventional beamforming system is the ability of the former to adjust its performance to suit differences in its environment.
A particularly important feature, in military applications, is the potential for an adaptive beamformer to reduce sensitivity to certain directions of arrival so as to counteract jamming by hostile transmissions.
Beamforming
Beamforming is a signal processing technique used in sensor arrays for directional signal transmission or reception. This is achieved by combining elements in the array in a way where signals at particular angles experience constructive interference and while others experience destructive...
system which performs adaptive spatial signal processing
Signal processing
Signal processing is an area of systems engineering, electrical engineering and applied mathematics that deals with operations on or analysis of signals, in either discrete or continuous time...
with an array of radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
antennas (or phased array
Phased array
In wave theory, a phased array is an array of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions.An antenna array...
) in order to transmit or receive signals in different directions without having to mechanically steer the array.
The main distinction between an adaptive beamformer and a conventional beamforming system is the ability of the former to adjust its performance to suit differences in its environment.
A particularly important feature, in military applications, is the potential for an adaptive beamformer to reduce sensitivity to certain directions of arrival so as to counteract jamming by hostile transmissions.
Adaptive Beamforming Schemes
- Least Mean SquaresLeast mean squares filterLeast mean squares algorithms are a class of adaptive filter used to mimic a desired filter by finding the filter coefficients that relate to producing the least mean squares of the error signal . It is a stochastic gradient descent method in that the filter is only adapted based on the error at...
Algorithm - Sample Matrix InversionSample matrix inversionSample matrix inversion is an algorithm that estimates weights of an array by replacing the correlation matrix Ru with its estimate...
Algorithm - Recursive Least SquareRecursive least squares filterThe Recursive least squares adaptive filter is an algorithm which recursively finds the filter coefficients that minimize a weighted linear least squares cost function relating to the input signals. This is in contrast to other algorithms such as the least mean squares that aim to reduce the...
Algorithm - Conjugate gradient methodConjugate gradient methodIn mathematics, the conjugate gradient method is an algorithm for the numerical solution of particular systems of linear equations, namely those whose matrix is symmetric and positive-definite. The conjugate gradient method is an iterative method, so it can be applied to sparse systems that are too...
- Constant Modulus Algorithm
See also
- BeamformingBeamformingBeamforming is a signal processing technique used in sensor arrays for directional signal transmission or reception. This is achieved by combining elements in the array in a way where signals at particular angles experience constructive interference and while others experience destructive...
is spatial signal processing which makes spatial beam focused on the target direction and spatial beam nulled interference signal. - Smart Antennas is multiple antenna systems having one of three structures which are single-input and multiple-output (SIMO), multiple-input and single-output (MISO), and multiple-input and multiple-output (MIMO) structures.
- MIMOMIMOIn radio, multiple-input and multiple-output, or MIMO , is the use of multiple antennas at both the transmitter and receiver to improve communication performance. It is one of several forms of smart antenna technology...
is an advanced smart antenna system which has multiple transmit antennas at the transmitter and multiple receive antennas at the receiver.