GPS In-Band Interference Mitigation via Deterministic Phase Control
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Solution Overview
Problem
Existing GPS signal reception technologies are inadequate in mitigating in-band interference, particularly spoofing and jamming, which can disrupt critical navigation and communication systems, due to their reliance on complex hardware, directional antennas, and limited angular operating range, making them unsuitable for widespread use.
Innovation Solution
The implementation of phase-controlled filtering using omnidirectional antennas and modifying circuitry that includes detectors, amplifiers, phase shifters, and combiners to selectively cancel interference by amplitude equalizing and phase shifting signals, allowing for enhanced GPS signal reception without the need for directional antennas or extensive spatial diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If array steering is used to reduce receiver sensitivity in the direction of jamming source, then interference mitigation is improved, but hardware complexity, size, weight, power consumption, and cost increase substantially
Solution Approach 1:
The patent extracts the interference signal from the composite received signal by detecting its characteristics (frequency, amplitude, phase) and separately processing it through a null generator, rather than using complex array steering hardware. This separates the interference cancellation function from the main signal reception path.
Solution Approach 2:
The patent introduces a null generator as an intermediary device that creates a cancellation signal based on detected interference characteristics. This mediator processes the interference separately and combines it with the original signal to achieve cancellation without requiring complex array hardware.
2Object-affected harmful factors
If array steering is used to reduce receiver sensitivity to interference, then interference mitigation is improved, but the payload capacity and energy requirements increase substantially
Solution Approach 1:
The system performs self-service by automatically detecting interference characteristics and generating appropriate cancellation signals without requiring external control or complex hardware reconfiguration. The null generator adapts to interference conditions in real-time using minimal power.
Solution Approach 2:
The patent changes the approach from physically steering antenna arrays (which requires substantial power) to electronically generating cancellation signals by modifying signal parameters (amplitude, phase, frequency) to match and cancel the interference.
3Reliability
If conventional filtering is used to reject frequencies outside desirable range, then signal to noise ratio is improved, but interference at passband frequencies cannot be mitigated
Solution Approach 1:
The patent performs preliminary detection of interference characteristics (frequency, amplitude, phase) before generating the cancellation signal. This preliminary action allows the system to prepare the appropriate null signal in advance, enabling effective cancellation of passband interference that conventional filters cannot handle.
4Object-affected harmful factors
If spatial diversity with directional antennas is used to defeat interference, then interference mitigation is improved, but signal quality from directions proximate to interference degrades
Solution Approach 1:
The patent applies local quality by creating a targeted cancellation signal that specifically addresses the interference from a particular direction or frequency, while leaving the desired signal from other directions unaffected. The null generator adjusts the cancellation signal's characteristics to match only the interference components.
5Device complexity
If fewer array elements are used to reduce system complexity, then device complexity is reduced, but the null broadens and cancels SI over wide ranges of bearing reducing overall system performance
Solution Approach 1:
The patent replaces the mechanical array steering system with an electronic signal processing approach. Instead of physically positioning multiple antenna elements to create narrow nulls, the system uses electronic generation of cancellation signals that can achieve precise interference rejection with minimal hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively cancels interference at any bearing, including boresight interference, while maintaining signal quality, reducing system complexity and cost, and enabling operation in compact, aerodynamic configurations, thus enhancing GPS signal-to-noise ratio and overall system performance.
Implementation Method 1
modifying circuitry that can modify signals from the second antenna... Phase shifting is conducted according to a deterministic solution providing anti-phase alignment of desirably mitigated signals at the combiner
Implementation Method 2
a combiner, and a controller... combining modified signals to selectively cancel interference content
Implementation Method 3
an emitter antenna of any type that can emit a modified second antenna signal
Data Source
AI summary
Methods, systems, and computer readable media for mitigation of interference of GPS signals are disclosed providing selective mitigation of in-band interference implementing deterministic phase control. In one embodiment, a system for mitigating interference of GPS signals includes a pair of antennas, each receiving GPS signals that include both a desired signal component and a jammer signal component. The signal from one antenna is phase-shifted as needed to make it anti-phase with the signal from the other antenna, so that when the two signals are combined, the jammer signal components substantially cancel each other, leaving the desired signal components. Determining the phase shift required involves deterministically calculating the phase shift based on the amplitudes of the two input signals and the amplitude of the combined signal instead of the iterative techniques used in conventional systems.