Position Fix Accuracy via Cross-Comparison of Solution Types
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Solution Overview
Problem
Navigation satellite systems face challenges in achieving accurate position fixes due to errors from multipath, jamming, atmospheric conditions, and erroneous integer ambiguity resolution, particularly in L2 carrier tracking which is less reliable and prone to errors compared to L1 signals.
Innovation Solution
The method involves comparing different position solution types, such as L1 code, L1 carrier float, and L1/L2 carrier fixed solutions, using a metric-based approach to identify and select the most accurate solution by determining if additional solutions are within a pre-defined offset distance threshold, thereby choosing the code solution as the final solution when others are outside this threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If L2 carrier tracking is used to improve position accuracy, then measurement precision is improved, but reliability deteriorates due to multipath, jamming, and erroneous integer ambiguity resolution
Solution Approach 1:
The patent uses L1 code solution as an intermediary reference to validate L2 carrier tracking solutions. By comparing L2 carrier-phase derived positions against L1 code positions (which are more reliable but less precise), the system can detect and reject erroneous L2 solutions caused by multipath, jamming, or integer ambiguity errors, thus maintaining both precision and reliability
Solution Approach 2:
The system implements feedback by continuously monitoring the consistency between L1 code solutions and L2 carrier solutions. When discrepancies exceed thresholds, the system flags potential errors in L2 tracking and adjusts its confidence in the L2 solution, creating a closed-loop validation mechanism that improves reliability without sacrificing the precision benefits of L2 carrier tracking
2Reliability
If multiple solution types are compared to identify errors, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the position solution process into distinct components: L1 code solution generation, L2 carrier solution generation, and cross-validation comparison. By dividing the problem into separate modular stages with clear interfaces, the system achieves robust error detection through multiple solution types while managing complexity through structured organization of processing steps
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 the accuracy of position fixes by identifying and mitigating errors in navigation satellite systems, particularly in scenarios where L2 tracking is unreliable, ensuring more robust and accurate location determination.
Implementation Method 1
NSS position determination is based upon a concept referred to as time of flight (TOF) ranging. The NSS receiver determines the time between transmission of the signal by the satellite and reception by the receiver. Multiplying this by the speed of light gives what is termed the pseudorange measurement of that satellite.
Data Source
AI summary
Embodiments provided herein recite methods and systems for an accuracy estimator for a position fix. In one embodiment, a solution receiver for receiving a code solution and at least one additional solution from a different solution technique is utilized. In addition, a table of metric values comprising an associated accuracy estimate for at least one characteristic of each of the code solution and the at least one additional solution is also utilized. A comparator compares the code solution and the at least one additional solution with the table of metric values. In addition, a solution orderer orders the at least one additional solution above or below the code solution dependent on whether the at least one additional solution is within a pre-defined offset distance threshold. If the at least one additional solution is outside of the distance threshold, the code solution is chosen as the final solution.