SBS Ground Station Navigation Relay for GPS Outages
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Solution Overview
Problem
Global Navigation Satellite Systems (GNSS) like GPS are not completely reliable, especially in obstructed areas or during outages, leading to potential common mode failures in aviation and other dependent systems, necessitating a reliable alternative for accurate navigation and timing.
Innovation Solution
The technique involves receiving time-slotted messages from ground radio stations, determining the time of transmission and reception, and using multi-lateration to compute the position of a mobile device, leveraging existing Surveillance and Broadcast Services (SBS) systems like UAT and 1090ES protocols to provide navigation and timing solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS satellite systems are used for navigation and timing, then accurate position determination is achieved, but system reliability deteriorates in obstructed areas and during outages
Solution Approach 1:
The patent introduces ground-based reference devices as intermediary elements between satellites and mobile devices. These reference devices receive satellite signals and re-broadcast them locally, creating a relay system that penetrates obstructed areas where direct satellite signals cannot reach, thereby maintaining both accuracy and reliability in GPS-denied environments
Solution Approach 2:
The patent transitions from purely space-based satellite navigation to a ground-based reference system operating in the terrestrial dimension. By establishing reference devices on the ground that create local coverage areas, the system adds a terrestrial layer to the space-based navigation architecture, enabling operation in urban canyons and obstructed environments where satellite signals are blocked
2Reliability
If ground-based radar systems are used for surveillance, then continuous monitoring is achieved, but navigation capability is lost
Solution Approach 1:
The patent makes ground-based reference devices multi-functional by enabling them to perform both surveillance and navigation functions simultaneously. The reference devices broadcast signals that mobile devices can use for position determination (navigation) while ground stations continue to monitor aircraft positions (surveillance), eliminating the need to choose between these functions
3Reliability
If VOR/DME devices are used for position derivation, then backup navigation is available, but accuracy and coverage are insufficient
Solution Approach 1:
The patent changes the operational parameters of ground-based reference devices by having them receive and re-broadcast satellite signals at specific frequencies and power levels. This creates a hybrid system that combines the reliability of ground-based infrastructure with the high accuracy of satellite positioning, achieving both backup capability and precise position determination that VOR/DME alone cannot provide
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 enables accurate navigation and timing over a wide geographic area, providing a seamless backup to GPS and synchronizing local clocks with reference devices, ensuring continuous and reliable operation even when GPS is unavailable.
Implementation Method 1
The mobile device determines the time of reception of each of the time-slotted messages and uses the received slot ID to determine the time of transmission of each of the time-slotted messages such that the mobile device can compute the propagation time of each message
Implementation Method 2
Multi-lateration can then be performed by the mobile device using the known positions of the reference devices and the signal propagation times (or ranges) to determine a navigation solution for the mobile device
Data Source
AI summary
A technique for determining the position of a mobile device includes receiving at the mobile device a set of time-slotted messages from a respective set of reference devices. Each of the time-slotted messages contains a slot ID indicating the assigned time slot in which it was broadcast. The slot ID is used to determine the time of transmission of each of the time-slotted messages received at the mobile device, and the position of the mobile device is determined via multi-lateration based on the time of flight of the time-slotted messages and known positions of the reference devices. According to another approach, the mobile device receives a set of ADS-B messages from a respective set of SBS ground stations. The time of transmission of each of the ADS-B messages is supplied in the ADS-B message itself or in a subsequent message and used to determined the position of the mobile device.