Cycle Slip Indicators for Regional GNSS Augmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Global Navigation Satellite Systems (GNSS) with regional augmentation face challenges in dealing with cycle slips, which affect the accuracy and availability of precise point positioning, particularly in achieving faster convergence and improved accuracy.
Innovation Solution
The method involves obtaining rover observations and correction data, including code biases and ionospheric corrections, to create synthetic reference data and detect cycle slips using indicators, then resetting affected state variables while retaining unaffected ones, and applying recursive filters to estimate updated values for ambiguities and rover position coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cycle slip detection and handling is implemented in regionally augmented GNSS, then positioning reliability is improved, but processing complexity increases
Solution Approach 1:
The patent segments the state variables into two distinct groups: those affected by cycle slips (carrier-phase ambiguities) and those unaffected (position coordinates, clock offsets, ionospheric delays). This segmentation allows selective resetting of only the affected variables when cycle slips are detected, rather than resetting all state variables. The segmentation is implemented through separate state vector components and selective initialization in the estimation algorithm, thereby improving reliability by properly handling cycle slips while avoiding unnecessary processing complexity.
2Reliability
If all state variables are reset when cycle slips occur, then positioning reliability is improved, but convergence time increases
Solution Approach 1:
The patent divides state variables into affected and unaffected categories, resetting only the affected carrier-phase ambiguity variables when cycle slips are detected, while preserving the unaffected position and clock variables. This selective resetting approach maintains positioning reliability by addressing the root cause (cycle slip in carrier phase) while avoiding the time loss associated with resetting all variables including those that remain valid.
Solution Approach 2:
The patent discards (resets) only the specific state variables that are corrupted by cycle slips (carrier-phase ambiguities) while recovering and retaining the valid unaffected variables (position estimates, clock offsets). This selective discarding and recovering process ensures that useful information is preserved while eliminating the harmful effects of cycle slips, thereby reducing convergence time compared to complete resetting.
3Productivity
If selective resetting of state variables is implemented, then convergence speed is improved, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent introduces cycle slip indicator variables as intermediaries that bridge the detection mechanism and the selective resetting process. These indicator variables are generated by the detection algorithm and serve as triggers for selective state variable resetting. The intermediaries simplify the overall process by providing clear signals about which variables need resetting, thereby enabling fast convergence without significantly increasing detection difficulty, as the indicators are naturally integrated into the existing detection framework.
Data Source
AI summary
Methods and apparatus for determining a precise position of a rover located within a region are presented using rover observations comprising code observations and carrier-phase observations of GNSS signals on at least two carrier frequencies over multiple epochs. Correction data is received for each of the epochs at least one code bias per satellite. Synthetic reference data is generated for each of the epochs from the correction data for a synthetic station location. A determination is made for each epoch whether a cycle slip has occurred. Upon determining that a cycle slip has occurred, values of any variables of a set of state variables which are affected by the cycle slip are reset. Each epoch of rover observations and correction data is used to estimate updated values for the set of state variables including a set of ambiguities and coordinates of a precise rover position.