GPS Cycle Slip Detection via Predicted Integrated Carrier Phase
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Solution Overview
Problem
Global positioning system (GPS) receivers experience disruptions due to GPS carrier phase cycle slips, which can occur frequently and impair precise relative position determination, especially in applications requiring high accuracy such as air travel, farming, and mining.
Innovation Solution
A method and apparatus for detecting and correcting GPS carrier phase cycle slips using a near real-time cycle slip detector that predicts integrated carrier phase changes based on vehicle dynamics, clock dynamics, and GPS satellite dynamics, allowing for the substitution of measured changes with analytical predictions when they exceed a threshold value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RTK carrier phase integer ambiguity resolution is used to achieve high positioning accuracy, then measurement precision is improved, but the system becomes vulnerable to cycle slips that cause positional disruptions
Solution Approach 1:
The system performs preliminary actions by predicting the expected carrier phase change before actual measurement is taken. The predicted carrier phase change is calculated based on vehicle dynamics, clock dynamics, and satellite dynamics, and is used to detect cycle slips by comparing with actual measurements. This allows the system to detect and correct positional disruptions before they affect the RTK positioning accuracy.
Solution Approach 2:
The system implements feedback by continuously monitoring the carrier phase measurements and comparing them against the predicted carrier phase change. When a discrepancy exceeds a threshold, indicating a cycle slip, the system uses the feedback information to correct the carrier phase measurement and maintain positioning accuracy. This closed-loop approach ensures both high precision and reliability.
2Measurement precision
If carrier phase tracking is used to determine position, then measurement precision is improved, but cycle slips cause harmful disruptions to the tracking accuracy
Solution Approach 1:
The system converts the harmful effect of cycle slips into a beneficial detection opportunity. By predicting the expected carrier phase change and comparing it with actual measurements, the system can detect when a cycle slip occurs. The predicted carrier phase change, which would normally be part of the positioning calculation, becomes a reference for detecting and correcting cycle slips, thus transforming a potential error source into a detection tool.
Solution Approach 2:
The predicted carrier phase change acts as an intermediary between the carrier phase measurement and the final position determination. It serves as a reference value that mediates the detection process, allowing the system to identify when the actual measurement deviates from the expected value due to cycle slips, and to correct the measurement before it affects positioning accuracy.
3Reliability
If real-time cycle slip detection is implemented using predicted carrier phase changes, then reliability is improved, but device complexity increases
Solution Approach 1:
The system achieves multi-functionality by using the same carrier phase tracking infrastructure for both positioning and cycle slip detection. The predicted carrier phase change is calculated using the same vehicle dynamics, clock dynamics, and satellite dynamics models that are already used for RTK positioning. This allows the detection function to be added without requiring entirely separate hardware or complex additional processing, thus improving reliability while limiting the increase in device complexity.
Data Source
AI summary
A method and detector for detecting a global positioning system (GPS) carrier phase (CP) cycle slip or correcting the GPS CP cycle slip is disclosed. A GPS CP cycle slip detector can include an integrated CP (ICP) change measurement module, an ICP change prediction module, and a processor. The ICP change measurement module can be configured for generating a measured ICP change of a measured CP of a GPS signal for a time duration. The ICP change prediction module can be configured for determining a predicted ICP change of the GPS signal CP for the time duration using directional position information. The processor can be configured for detecting in near real time a GPS CP cycle slip when the measured ICP change varies from the predicted ICP change by greater than a threshold value.