GNSS Carrier Phase Synthesis for Half-Cycle Ambiguity Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing GNSS systems face challenges in resolving half-cycle ambiguity in carrier phase measurements, particularly in BPSK-modulated ranging signals, which are not distinguishable from navigation bit inversions, leading to inaccuracies and the need for frequent recalibration upon signal interruptions.
Innovation Solution
A method involving the determination of a bias term for a synthetic carrier phase function that mimics the target data carrier phase, allowing for half-cycle ambiguity resolution without requiring recalibration, using unambiguous phase information from a different source, such as a reference carrier, and leveraging pseudorange measurements to derive the target carrier phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the receiver uses preamble-based methods to resolve half-cycle ambiguity, then the ambiguity can be resolved, but the process requires frequent restart after signal interruptions and is not independent of time
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing synthetic carrier phase values based on navigation message content before actual ambiguity resolution is needed. The synthetic carrier phase function is prepared in advance using the known navigation message structure, allowing immediate comparison with measured phases without waiting for preambles or previous tracking data.
Solution Approach 2:
The patent uses copying by creating a synthetic carrier phase function that replicates the expected carrier phase behavior based on navigation message content. This synthetic copy allows direct comparison with actual measured phases to detect half-cycle ambiguities, eliminating the need for actual carrier phase tracking over time.
2Reliability
If the receiver waits for preamble occurrence to resolve half-cycle ambiguity, then the ambiguity can be determined, but the process must restart after each signal interruption and cannot be applied independently at any time
Solution Approach 1:
The patent applies preliminary action by pre-computing synthetic carrier phase values based on navigation message content before actual ambiguity resolution is needed. The synthetic carrier phase function is prepared in advance using the known navigation message structure, allowing immediate comparison with measured phases without waiting for preambles or previous tracking data.
Solution Approach 2:
The patent uses copying by creating a synthetic carrier phase function that replicates the expected carrier phase behavior based on navigation message content. This synthetic copy allows direct comparison with actual measured phases to detect half-cycle ambiguities, eliminating the need for actual carrier phase tracking over time.
3Difficulty of detecting and measuring
If the receiver uses extrapolation-based cycle-slip detection, then recent discontinuities can be detected, but the method requires recent data and extrapolation quickly diverges
Solution Approach 1:
The patent uses copying by creating a synthetic carrier phase function that replicates the expected carrier phase behavior based on navigation message content. This synthetic copy allows direct comparison with actual measured phases to detect half-cycle ambiguities, eliminating the need for actual carrier phase tracking over time.
Solution Approach 2:
The patent introduces an intermediary approach by using synthetic carrier phase values as a mediator between the navigation message content and the measured carrier phases. This intermediary allows direct comparison without requiring continuous tracking or extrapolation, as the synthetic function is derived directly from the navigation message structure.
Data Source
AI summary
The application pertains to a method for determining a phase of a target data carrier in a GNSS system, the method comprising: in an initialization phase: determining, at a first point in time, a bias term of a synthetic carrier phase function constructed to mimic a phase of the target data carrier; and in an operational phase: using said bias term determined in said initialization phase, obtaining a value of the synthetic carrier phase function, said value corresponding to a second point in time; and comparing a measured phase of the target data carrier at the second point in time to said value to assess the presence or absence of a half-cycle phase discrepancy; wherein said synthetic carrier phase function is constructed to mimic said phase of said target data carrier at points in time subsequent to said first point in time without requiring readjustment of said determined bias term.