LEO Satellite Signal Reception for Jammed Navigation
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Solution Overview
Problem
Existing satellite navigation and timing systems, such as GPS, face challenges in providing satisfactory performance in attenuated or jammed environments due to insufficient signal power and geometry, leading to unreliable positioning and time transfer, especially in urban areas.
Innovation Solution
A method and receiver unit design that utilize precision time signals from Low Earth Orbit (LEO) satellites, like Iridium, to determine precise absolute time, combined with aiding information from other sources, enabling effective navigation and signal detection even in heavily attenuated or jammed conditions by aligning system correlators for improved signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS signals are used for navigation and time transfer, then positioning and timing information can be obtained, but signal power is insufficient to penetrate urban canyons or building walls
Solution Approach 1:
The patent combines GPS signal reception with LEO satellite signal reception in a unified receiver system. The LEO satellite signals serve as auxiliary high-power signals that complement the weak GPS signals, enabling the receiver to obtain reliable positioning and timing information even when GPS signals are attenuated by urban canyons or building walls.
Solution Approach 2:
The patent introduces LEO satellite signals as an intermediary high-power source that mediates between the weak GPS signals and the receiver. These LEO signals provide sufficient power to penetrate obstructed environments and serve as a reference that enhances the detectability and reliability of GPS signal acquisition in challenging urban environments.
2Measurement precision
If GPS receivers require four simultaneous ranging sources for accurate time transfer, then positioning accuracy is improved, but detection efficiency decreases in attenuated environments
Solution Approach 1:
The patent performs preliminary detection and tracking of LEO satellite signals before attempting to detect GPS signals. By first acquiring the high-power LEO signals and extracting timing information from them, the receiver prepares optimal detection parameters and timing references that significantly improve the efficiency of subsequent GPS signal detection, reducing the time and computational resources needed to achieve four-satellite lock.
Solution Approach 2:
The patent implements a feedback mechanism where LEO satellite signal detection results are used to adjust and optimize GPS signal detection parameters. The timing and frequency information derived from LEO signals provides feedback that refines the receiver's local oscillator settings and correlation parameters, thereby improving detection efficiency and reducing the time required to acquire sufficient GPS satellites for accurate time transfer.
3Reliability
If specialized beacons are deployed for indoor navigation, then positioning capability is improved, but system complexity and cost increase
Solution Approach 1:
The patent enables existing LEO communication satellites to serve dual purposes: their primary communication function and a secondary navigation/timing function. By extracting positioning and timing information from standard LEO communication signals, the system provides indoor navigation capability without requiring specialized navigation satellites or ground-based beacon infrastructure, thereby reducing system complexity while maintaining reliability.
Data Source
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AI summary
Systems and methods according to one or more embodiments are provided for obtaining a precise absolute time using a satellite system. The precise absolute time may be used, for example, as an aid for positioning systems including navigation in attenuated or jammed environments. A method of obtaining precise absolute time transfer from a satellite according to an embodiment comprises: receiving a precision time signal from a satellite, wherein the precision time signal comprises a periodic repeating code; determining a timing phase of the code; receiving additional aiding information; and using the timing phase and the additional aiding information to determine a precise absolute time.