Blind LEO Signal Navigation Using Doppler Estimation and Beacon Tracking
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Solution Overview
Problem
Existing navigation systems face challenges in acquiring and tracking satellite signals from low Earth orbit (LEO) broadband systems due to the lack of publicly available signal specifications, making it difficult for regular receivers to blindly detect and navigate using these signals.
Innovation Solution
A blind opportunistic navigation (BON) framework that enables the acquisition and tracking of partially known signals of opportunity (SOPs) by employing algorithms for blind Doppler estimation and beacon signal detection, allowing receivers to decipher and navigate using LEO satellite signals without prior knowledge of their specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing navigation systems use traditional GNSS signals, then navigation reliability is high, but the system is vulnerable in GNSS-challenged environments
Solution Approach 1:
The patent changes the fundamental parameter of signal acquisition from requiring known signal specifications to enabling blind signal acquisition. By implementing blind Doppler estimation and coherent integration algorithms, the system can acquire LEO satellite signals without prior knowledge of their modulation parameters, thereby achieving adaptability to unknown signal environments while maintaining navigation reliability
Solution Approach 2:
The patent creates a universal navigation receiver that can operate with multiple types of satellite signals (traditional GNSS and experimental LEO signals) using the same blind acquisition framework. This multi-functional capability allows the receiver to adapt to different signal specifications dynamically, resolving the contradiction between reliability and adaptability
2Adaptability or versatility
If receivers use blind signal acquisition for LEO satellites, then adaptability to unknown signals is improved, but signal detection accuracy deteriorates due to lack of signal specifications
Solution Approach 1:
The patent applies preliminary action by performing blind Doppler estimation before coherent integration. This preliminary frequency offset estimation enables the system to prepare the signal for subsequent coherent integration, thereby maintaining detection accuracy even without known signal specifications. The preliminary action of Doppler estimation is crucial for achieving both adaptability and precision
Solution Approach 2:
The patent implements feedback mechanisms where the receiver continuously monitors signal characteristics and adjusts its blind acquisition parameters accordingly. The feedback from signal detection results is used to refine the Doppler estimation and coherent integration process, thereby maintaining high detection accuracy while operating in blind mode with unknown signal specifications
3Measurement precision
If the system performs coherent integration to estimate beacon sequences, then navigation precision is improved, but computational complexity increases
Solution Approach 1:
The patent segments the coherent integration process into manageable stages: first performing blind Doppler estimation, then using that estimate to guide the coherent integration of beacon sequences. This segmentation allows the system to achieve high navigation precision through coherent integration while managing computational complexity by breaking down the overall processing into distinct, optimized stages rather than a single complex operation
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
The BON framework achieves high accuracy in detecting beacon sequences, with an average of 96% correct chip detection performance for GPS satellites, providing reliable navigation solutions even in GNSS-challenged environments.
Implementation Method 1
performing at least one operation to estimate a Doppler frequency of the at least one signal
Data Source
AI summary
Systems, device configurations, and processes are provided for blind opportunistic navigation (BON) including cognitive deciphering of partially known signals of opportunity and blind Doppler estimation from LEO satellite signal. In one embodiment a method includes receiving a signal of opportunity and using a framework for BON. In one embodiment, the framework includes performing blind Doppler estimation and tracking, performing coherent integration, and performing blind beacon detection/tracking. Coherent integration may be performed once a blind estimate of the Doppler is produced, and detecting symbols of a beacon sequence is performed for at least one of acquiring, tracking, and navigating with the received signal of opportunity. According to another embodiment, a method for blind Doppler estimation, includes receiving a signal of opportunity, performing an initial wipe-off operation, performing a blind residual Doppler estimation, and performing a Doppler ambiguity resolution.