Moore-Penrose Inverse Spatial Signal Separation for Satellite Navigation
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Solution Overview
Problem
Conventional spatial signal separation methods in satellite navigation systems, such as GPS, are limited by their assumption of a one-signal model in multiple-signal environments, leading to interference and jamming vulnerabilities due to signal leakage from unwanted signals.
Innovation Solution
The method employs a multiple signal model using the Moore-Penrose inverse to decouple satellite navigation signals from interfering signals by mapping them onto an antenna array, effectively separating signals of interest from interfering ones, even when the interfering signals are stronger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional array processing techniques (null beam steering, CRPA, sidelobe cancellation) are used to reject unwanted interference, then signal separation is attempted, but signal leakage from other signals occurs due to the incorrect one-signal model assumption in multiple-signal environments
Solution Approach 1:
The patent changes the fundamental mathematical model parameter from a one-signal assumption to a multiple-signal model. This parameter change in the mathematical construct allows the system to correctly handle multiple simultaneous signals, eliminating the signal leakage problem that occurs when conventional one-signal methods are applied to multiple-signal environments.
Solution Approach 2:
The patent substitutes the conventional mechanical/array processing approach (null beam steering, CRPA) with a mathematical substitution using the Moore-Penrose inverse. This mathematical substitution provides a more accurate inversion mechanism that properly separates multiple signals without the leakage issues inherent in conventional methods.
2Area of stationary object
If GPS signals are transmitted from high orbits to provide wide coverage, then navigation service area is expanded, but signal strength becomes very weak and vulnerable to jamming and spoofing
Solution Approach 1:
The patent converts the harmful effect of strong interfering signals into a benefit by using their known directional characteristics. The system exploits the fact that jamming and spoofing signals, while harmful, have identifiable directions of arrival that can be used to construct accurate steering vectors, which then enable more effective spatial filtering and separation of desired GPS signals from interference.
3Object-generated harmful factors
If spatial separation methods introduce time delays or phase shifts to place nulls in interference directions, then interference rejection is achieved, but the complexity of accurately estimating direction of arrival increases
Solution Approach 1:
The patent applies preliminary action by using known satellite orbital data from the broadcast ephemeris to pre-determine the expected directions of arrival of legitimate GPS signals. This preliminary knowledge allows the system to focus computational effort on identifying and rejecting signals that do not match the expected satellite positions, thereby simplifying the overall direction of arrival estimation process.
Data Source
AI summary
In a multiple signal environment, it is important to be able to separate signals. Complete spatial separation can only be accomplished by following the proper mathematical method. This involves first modeling multiple signals that map onto an antenna array. Inverting this process by use of the Moore-Penrose inverse results in spatially separating the signals of interest. This method has important applications in satellite navigation systems where it is relatively easy to jam or spoof the valid but weak navigation signals coming from satellites in high orbits.