Adaptive Beamforming Weights for Signal Angle Detection
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Solution Overview
Problem
Conventional adaptive beam-forming techniques distort the output signal time functions while rejecting interference, which is undesirable in applications like radio astronomy and communication systems where accurate phase information is critical.
Innovation Solution
The technique determines the angles of arrival of signals, including interference, by using adaptive beam-forming weights to generate an annihilation operator that can identify and eliminate interference without distorting the signal, enabling the use of this information in algebraic interference cancellation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive beam-forming techniques are used to reject interference by placing nulls in the beam pattern, then the signal-to-interference ratio is improved, but the output signal time functions are distorted
Solution Approach 1:
The patent segments the signal processing into two independent parts: (1) using adaptive beam-forming weights to determine interference directions, and (2) applying algebraic interference cancellation to eliminate interference. This segmentation allows the system to extract interference direction information without applying the distorting beam pattern to the actual signal, thus avoiding signal distortion while maintaining interference rejection capability.
Solution Approach 2:
The patent introduces an intermediary step where adaptive beam-forming weights are used solely to identify interference directions, which then serve as input parameters for the algebraic interference cancellation process. This intermediary use of beam-forming weights allows the system to leverage their interference-detection capability without subjecting the actual signal to the distorting beam pattern transformation.
2Loss of information
If algebraic interference cancellation is used to eliminate interference without distorting signals, then signal properties are preserved, but the direction of interference must be known in advance
Solution Approach 1:
The patent makes the system self-sufficient by using the adaptive beam-forming weights (which are already being computed for interference rejection) to automatically determine the interference directions needed by the algebraic interference cancellation process. The system uses its own internal resources (the beam-forming weights) to solve the problem of interference direction identification, eliminating the need for external or separate direction-finding mechanisms.
3Object-generated harmful factors
If conventional beam-forming nulling is used to reject interference, then interference is eliminated, but the beam pattern is distorted and signal structure is lost
Solution Approach 1:
The patent extracts only the necessary information (interference directions) from the adaptive beam-forming weights without applying the full beam-forming transformation that distorts the signal. By taking out just the directional information and using it to construct the annihilation operator for algebraic interference cancellation, the system achieves interference rejection while preserving the original beam pattern and signal structure.
Data Source
AI summary
A technique for determining the angles of arrival of signals incident on an antenna array from directions within an angular region of interest involves supplying outputs of antenna elements of the antenna array to a number of different weight generators. Each of the weight generators produces a set of beam-forming weights that maximizes a signal-to-interference ratio of a locally generated signal corresponding to a look angle that is outside the region of interest, with signals at different look angles being supplied to the different weight generators. An annihilation operator is determined from the sets of beam-forming weights generated by the weight generators and from beam-forming vectors representing the look angles of the locally generated signals used in the weight generators. The annihilation operator is applied to a group of beam-forming vectors representing angles within the region of interest to determine angles of arrival of signals within the region of interest.