GNSS Vector Tracking Loop for Multi-Constellation Signal Integration
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Solution Overview
Problem
Current GNSS receivers rely on scalar tracking methods that separate signal tracking and navigation solution determination, requiring multiple loops and configurations for different satellite constellations, which can be inefficient and prone to multipath interference, especially in low SNR environments.
Innovation Solution
The apparatus and method employ a velocity hypothesis unit to generate and determine the most likely velocity hypothesis based on navigation engine outputs, using correlators to calculate correlation values between expected and true Doppler shifts across multiple satellites, integrating these values to improve signal tracking and reduce the number of tracking loops needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If scalar tracking methods are used with separate tracking loops for each satellite constellation, then signal tracking can be performed for multiple constellations, but the device complexity increases and tracking sensitivity decreases in low SNR environments
Solution Approach 1:
The patent combines tracking of multiple GNSS constellations into a single vector tracking loop that processes signals from all constellations simultaneously. Instead of maintaining separate tracking loops for each constellation, the system uses one unified vector tracker that handles GPS, Galileo, GLONASS, and BeiDou signals together, reducing the number of tracking loops while maintaining multi-constellation capability
Solution Approach 2:
The vector tracking loop is designed as a universal tracker that can process signals from any GNSS constellation using a common mathematical model. The tracker uses velocity hypotheses that are constellation-agnostic, allowing the same tracking structure to universally handle different satellite systems without requiring constellation-specific configurations
2Reliability
If separate tracking loops are used for each satellite constellation, then each constellation can be tracked independently, but the tracking sensitivity and SNR performance deteriorate
Solution Approach 1:
The system merges measurements from multiple constellations into a single vector tracking solution, combining the signal energy from all available satellites. This coherent combination improves the effective SNR and tracking sensitivity compared to processing each constellation separately, especially in low signal conditions
3Reliability
If conventional scalar tracking with nested code and carrier loops is used, then signal tracking can be performed, but the integration time increases and multipath rejection capability decreases
Solution Approach 1:
The vector tracking loop dynamically adjusts velocity hypotheses based on predicted receiver motion and selects the most likely hypothesis using correlation metrics. This dynamic adaptation allows the tracker to respond quickly to changing signal conditions without requiring long integration times, improving both response time and multipath rejection
Solution Approach 2:
The system uses correlation values as feedback to evaluate and select among velocity hypotheses. By continuously monitoring correlation metrics and adjusting the selected hypothesis accordingly, the tracker achieves rapid convergence and maintains accurate tracking with shorter integration periods compared to conventional scalar methods
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 enhances signal tracking sensitivity, reduces integration time, improves multipath rejection, and allows for coherent combination of satellite signals from multiple constellations, increasing overall signal power and SNR.
Implementation Method 1
a plurality of second signals, the second signals comprising true Doppler shifts derived from respective ones of the plurality of satellite signals
Data Source
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AI summary
An apparatus for vector tracking a plurality of satellite signals received by a Global Navigation Satellite System (GNSS) receiver from a plurality of satellites and a method for use thereof. The apparatus comprises: a hypothesis determiner configured to determine a most likely velocity hypothesis from a plurality of velocity hypotheses based on a plurality of correlation values, and to transfer data related to the most likely velocity hypothesis to a navigation engine of the GNSS receiver for tracking the satellite signals,wherein the plurality of velocity hypotheses have been generated based on a navigation engine output indicative of a current and/or a previous extended velocity solution for the GNSS receiver;and wherein the plurality of correlation values have been determined by a plurality of correlators and represent correlations between a plurality of first signals each comprising an expected Doppler shift derived from one of the plurality of velocity hypotheses,and a plurality of second signals each comprising a true Doppler shift derived from one of the plurality of satellite signals.