Geolocation Using RF Signals of Opportunity
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Solution Overview
Problem
Current geolocation and navigation systems face challenges in maintaining accuracy in GPS-denied environments due to signal obstruction and jamming, and existing methods using Signals of Opportunity (SoOPs) face limitations such as unsynchronized timing and variable power levels, making them impractical for high-precision navigation.
Innovation Solution
A system and method utilizing multiple cooperating networked nodes to capture and share measurements from heterogeneous, apriori known and unknown, synchronized and unsynchronized RF sources, employing the SMARTS algorithm for simultaneous mapping and relative timing, and the Hybrid Iterative GPS/SoOP Solution (HIGSS) to provide robust and accurate geolocation and navigation, even in the absence of timing references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional GPS user equipment research topics (receiver sensitivity, reference oscillator stability, correlator speed, signal processing algorithm performance) are improved, then positional accuracy is improved incrementally, but the benefits are diminishing and large gains cannot be achieved
Solution Approach 1:
The system uses multiple RF signal sources (TV broadcasts, satellite-based communications networks, cellular signals) for navigation purposes, not just GPS. These signals were originally designed for other purposes (information transmission, communications) but are now multi-used for geolocation and navigation, enabling large performance gains without requiring each signal source to be optimized solely for navigation
Solution Approach 2:
The system changes the fundamental approach from improving GPS-specific parameters (receiver sensitivity, oscillator stability) to utilizing signals with different characteristics (high power, wide bandwidth, excellent time resolution) that were previously unused for navigation. This parameter change enables tremendous potential for robust and jam-proof navigation solutions
2Reliability
If Signals of Opportunity (SoOPs) such as TV broadcasts and satellite-based communications networks are used for navigation, then geolocation accuracy and availability are improved, but challenges arise due to unsynchronized timing and variable power levels
Solution Approach 1:
The patent introduces reference timing stations as intermediaries that provide timing references for SoOP signals. These stations enable the system to handle unsynchronized signals by providing a common time reference, thus resolving the timing synchronization challenge without requiring complex processing of completely unsynchronized signals
Solution Approach 2:
The system performs preliminary characterization of SoOP signals, including measuring and storing timing relationships and signal characteristics at known locations. This preliminary action enables the system to compensate for timing variations and power level changes when the signals are later used for navigation, reducing the complexity of real-time processing
3Device complexity
If power-based measurements of SoOPs are used for location estimation, then system complexity is reduced, but accuracy is insufficient for GPS-grade precision
Solution Approach 1:
The patent merges timing-based measurements and power-based measurements into a hybrid approach. Timing measurements provide the foundation for GPS-grade accuracy while power-based measurements supplement the solution, particularly in challenging environments. This combination achieves high accuracy without requiring extremely complex timing-only systems
4Adaptability or versatility
If GPS signals are used in GPS-denied environments (inside buildings, urban canyons), then navigation coverage is improved, but signal obstruction and jamming cause degraded accuracy or non-availability
Solution Approach 1:
The system converts the harmful effect of GPS signal obstruction and jamming into an opportunity to use alternative RF signals. By designing navigation systems that can utilize signals originally intended for other purposes (TV broadcasts, cellular communications), the system turns the limitation of GPS-denied environments into a benefit where these alternative signals provide robust navigation capability where GPS fails
Data Source
AI summary
A system and method to opportunistically capture and use measurements of barometric readings from a plurality of mobile agents to determine the elevational position of one of the mobile agents.