GNSS Receiver Stale Navigation Detection
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Solution Overview
Problem
GNSS receivers face challenges in achieving a timely position fix due to unfriendly RF environments and inconsistent navigation information, leading to incorrect measurement predictions and prolonged time to first fix (TTFF).
Innovation Solution
The method involves a GNSS receiver with a storage module for measurement predictions, a first channel set for searching satellite signals based on predictions, and a second channel set for searching a reference satellite without predictions, with a controller determining consistency between measurements and predictions, and adjusting search strategies accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the GNSS receiver uses measurement predictions from stored navigation information to search for satellite signals, then the time to first fix (TTFF) is reduced, but the receiver may fail to achieve position fix when navigation information is inconsistent with real operating conditions
Solution Approach 1:
The system performs preliminary actions by storing navigation information and generating measurement predictions in advance to reduce TTFF. However, it also implements a verification step where a reference satellite channel searches without predictions to validate the predictions before full reliance, thus preventing failure due to stale information.
Solution Approach 2:
The system uses feedback by comparing measurements from the reference satellite channel (searching without predictions) with the predicted measurements. When inconsistency is detected, the system discards the incorrect predictions and updates the search strategy, ensuring reliability while maintaining efficiency.
2Productivity
If the GNSS receiver searches for satellite signals using incorrect measurement predictions, then the search continues in wrong directions, but the receiver cannot identify that the predictions are incorrect without additional verification
Solution Approach 1:
The system introduces an intermediary reference satellite channel that searches for satellite signals without using measurement predictions. This intermediary channel serves as a verification mechanism to detect whether the predictions are correct by comparing its measurements with the predicted values, thus solving the difficulty of detecting prediction accuracy.
3Adaptability or versatility
If the GNSS receiver maintains multiple channel sets for different search strategies, then the ability to handle inconsistent navigation information improves, but the device complexity increases
Solution Approach 1:
The system segments the satellite signal search function into multiple independent channel sets: one channel set that uses measurement predictions for efficient searching, and another reference channel set that searches without predictions for verification. This segmentation allows the system to handle inconsistent navigation information while maintaining manageable complexity through modular design.
Data Source
AI summary
Methods and apparatuses for searching for satellite signals are provided. One of the proposed methods of searching for satellite signals includes: searching for satellite signals according to measurement predictions; searching for satellite signals of a reference satellite without referring to the measurement predictions; determining if measurements derived from the reference satellite are consistent with the measurement predictions; and searching for satellite signals of other satellites without referring to the measurement predictions if the measurements derived from the reference satellite are determined to be inconsistent with the measurement predictions. If the measurements derived from the reference satellite are determined to be inconsistent with the measurement predictions, navigation information for use in the generation of the measurement predictions is determined to be stale.