Passive Direction Finding Navigation for GPS-Denied Positioning
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Solution Overview
Problem
Existing GPS systems are vulnerable to jamming and spoofing, necessitating a backup navigational capability for critical platforms.
Innovation Solution
Employing an onboard direction finding (DF) system to determine position location using azimuth and elevation angles from a known remote signal source, such as satellites or UAVs, and integrating it with inertial navigation and computational processing to calculate latitude and longitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS systems are used for navigation, then position location accuracy is improved, but vulnerability to jamming and spoofing increases
Solution Approach 1:
The patent introduces an intermediary system (DF system with antenna array) that mediates between the vulnerable GPS receiver and the external signal environment. This intermediary enables alternative position determination through phase interferometry of non-GPS signals, breaking the direct dependency on vulnerable GPS signals while maintaining navigation capability.
Solution Approach 2:
The patent changes the fundamental parameter of signal frequency band from GPS L-band to other radio frequency bands (HF, VHF, UHF). By operating in different frequency bands and using different signal sources (terrestrial radio stations, satellites, drones), the system achieves parameter diversity that makes simultaneous jamming of all bands difficult and eliminates dependency on GPS-specific vulnerabilities.
2Reliability
If backup navigational capability is implemented, then navigational safety is improved, but device complexity increases
Solution Approach 1:
The DF system with antenna array is designed to be multi-functional: it can receive signals from various sources (terrestrial stations, satellites, drones), operate in multiple frequency bands, and provide both primary navigation capability and backup functionality. This universal design reduces overall system complexity compared to maintaining separate dedicated backup systems.
Solution Approach 2:
The patent merges the backup navigation functionality into the existing DF system architecture, combining signal reception, phase interferometry processing, and position calculation into a unified system. The antenna array serves both signal intelligence gathering and navigation purposes, eliminating the need for separate backup hardware and reducing overall system complexity.
3Reliability
If direction finding system with antenna array is deployed, then position location reliability is improved, but device complexity and size increase
Solution Approach 1:
The antenna array is segmented into multiple independent antenna elements that can be independently configured and processed. Each element receives signals and contributes to the overall phase interferometry measurement, allowing the system to achieve reliable position determination through distributed sensing rather than a single complex antenna structure.
Solution Approach 2:
The patent replaces complex mechanical position determination mechanisms with electromagnetic field-based phase interferometry. Instead of using mechanical sensors or complex mechanical positioning systems, the solution uses signal phase differences measured by the antenna array, substituting mechanical complexity with electromagnetic field processing that can be implemented with standard RF components.
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
Provides reliable position location information for continuous navigation even when GPS is jammed or spoofed, enhancing navigational safety and reliability.
Implementation Method 1
The waveform and the data structure have been known to the public ever since. Unfortunately, some hostile groups have taken advantage of such generous offering to create threats to the general GPS users
Data Source
AI summary
An apparatus and method of determining the position location of a moving platform without using any GPS signals such as in the GPS-denial environment is disclosed. A direction finding system is employed to receive signals from a source of known position location and to compute the look angles. The look angles include the azimuth and the elevation information. The position location (e.g., latitude and longitude) of the moving platform is determined from the computed azimuth and elevation and the known position location of a remote signal source. There is no interactive communications required between the moving platform and the remote signal source. Consequently, the disclosed method is a passive approach employing a direction finding system to determine the position location of the moving platform from the received non-GPS signals. The position location obtained via this method is also applicable to GPS spoofing detection when the GPS is considered available.