Wideband Signal Angle Estimation Using Iterative Beam Stabilization
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Solution Overview
Problem
Maximum likelihood angle estimation techniques fail to accurately determine the angle of arrival for wideband signals when used with electronically scanned phased array antennas, as they assume frequency invariance, which is not valid for wideband or spread spectrum waveforms.
Innovation Solution
The method involves stabilizing spatial frequency data in a consistent direction using convolutional processing, forming a covariance matrix, and iteratively recalculating the stabilization direction until an accuracy condition is met, allowing for frequency-invariant angle estimation of wideband signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If maximum likelihood angle estimation is used with electronically scanned phased array antennas, then angle estimation can be performed, but the estimation becomes inaccurate for wideband signals due to frequency variation assumptions
Solution Approach 1:
The patent applies dynamics by making the stabilization direction adjustable and iterative rather than fixed. The beam stabilization direction is dynamically updated based on estimated target direction, allowing the system to adapt to frequency variations in wideband signals while maintaining angle estimation accuracy
Solution Approach 2:
The patent changes the parameter of beam stabilization direction from a static value to a dynamically updated value based on iterative estimation. By modifying this parameter throughout the processing, the system accommodates frequency variations across the wideband signal spectrum
2Measurement precision
If beam stabilization is applied to wideband signals, then angle estimation can be performed, but deterministic high-order errors are introduced
Solution Approach 1:
The patent uses feedback by iteratively updating the beam stabilization direction based on the estimated target direction. This feedback loop allows the system to correct for deterministic errors by continuously refining the stabilization direction until convergence is achieved
Solution Approach 2:
The patent replaces the traditional fixed mechanical beam stabilization approach with a computational iterative method. Instead of relying on a single static stabilization direction that introduces errors, the system uses algorithmic iteration to compute and update the stabilization direction, eliminating deterministic high-order errors
3Measurement precision
If iterative stabilization direction updating is performed, then angle estimation accuracy improves, but computational complexity increases
Solution Approach 1:
The patent applies partial action by performing iterative updates only when necessary to achieve the required accuracy threshold. The iteration continues until the stabilization direction accuracy condition is met, avoiding unnecessary computational steps while ensuring sufficient precision
Data Source
AI summary
A method for estimating a target direction of a wideband signal received on an electronically steered array includes: applying convolutional or stretch processing to spatial frequency data of the wideband signal; initializing a stabilization direction to a beam pointing direction; stabilizing the spatial frequency data to the stabilization direction; compressing the spatial frequency data to a plurality of frequency range or time bins; selecting range or time bins and forming a covariance matrix; calculating an estimated target direction using the covariance matrix; determining if a stabilization direction accuracy condition is met; recalculating the stabilization direction based on the estimated target direction if the stabilization direction accuracy condition is not met; and iteratively repeating until the stabilization direction accuracy condition is met.