Pseudolite Network for Underground Navigation
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Solution Overview
Problem
Existing navigation systems face challenges in providing accurate positioning in areas with limited satellite coverage, such as underground spaces, due to the inability of Global Navigation Satellite Systems (GNSS) receivers to derive a Position, Navigation, and Time (PNT) solution when the number of visible satellites falls below the minimal requirements.
Innovation Solution
The implementation of a system that uses pseudolites, or pseudo-satellites, to simulate GNSS signals within underground spaces by configuring and controlling a network of transmitters to broadcast satellite signals based on determined satellite parameters, including signal modulation and broadcast data parameters, to mimic the signals from orbiting satellites, thereby maintaining navigation functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS receivers rely on visible satellites for positioning, then positioning accuracy is maintained in open sky conditions, but navigation fails in areas with limited satellite coverage such as underground spaces
Solution Approach 1:
The patent introduces pseudolites as intermediary devices that transmit satellite-like signals in underground environments where real satellites are not visible. These pseudolites act as mediators between the GNSS receiver and the positioning function, enabling navigation in limited coverage areas by providing synthetic satellite signals that the receiver can process normally
Solution Approach 2:
The patent creates copies of satellite signals through pseudolites that transmit synthetic GNSS signals identical in structure and format to real satellite transmissions. By copying the satellite signal characteristics and embedding simulated ephemeris data, the system enables receivers to obtain positioning solutions in environments where actual satellites are not visible
2Adaptability or versatility
If beacon transmitters are used to simulate satellite signals indoors, then indoor navigation is enabled, but the solution is limited to indoor applications and cannot provide continuous coverage in transitional zones
Solution Approach 1:
The patent merges the functionality of real satellite signals with pseudolite signals into a unified GNSS positioning system. The receiver processes both satellite and pseudolite signals through the same signal acquisition and tracking channels, seamlessly combining external satellite coverage with local pseudolite coverage to provide continuous navigation across transitional zones between indoor and outdoor environments
Solution Approach 2:
The patent implements dynamic signal selection and weighting where the receiver automatically adapts between satellite signals and pseudolite signals based on availability and quality metrics. The system dynamically adjusts the mix of signals used for positioning, maintaining reliability during transitions by switching between satellite dominance in open sky and pseudolite dominance in underground areas
3Measurement precision
If pseudolites are configured with accurate satellite parameters, then navigation accuracy is maintained, but system complexity increases due to parameter determination and configuration requirements
Solution Approach 1:
The patent performs preliminary determination of satellite parameters including simulated ephemeris data, clock corrections, and orbital elements before configuring the pseudolites. By pre-calculating these parameters based on the pseudolite locations and desired signal characteristics, the system ensures accurate positioning without requiring complex real-time parameter generation, reducing operational complexity while maintaining precision
Data Source
AI summary
A system and method for providing navigation through an underground space. The method includes receiving ephemeris data of a plurality of satellites in orbit at a location of the underground space, determining a schedule of the plurality of satellites in orbit, obtaining location of a plurality of pseudolites within the underground space, and determining satellite parameters to configure each of the plurality of pseudolites. Satellite parameters are determined based on the obtained location of each pseudolites and the determined satellite schedule. Also, the satellite parameters include at least a signal modulation parameter and a broadcast data parameter. The method also includes configuring each of the plurality of pseudolites with the respective satellite parameters, and controlling the plurality of pseudolites to broadcast satellite signals based on the determined satellite parameters. The broadcasted satellite signals simulate locations of the plurality of satellites in orbit.