GNSS Carrier Phase Motion Detection for Base Station Movement
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Solution Overview
Problem
Existing differential navigation systems rely on fixed base stations, and any movement of these stations can compromise the accuracy of position determination for mobile rovers, with potential for unpredictable consequences, especially in unattended or critical environments.
Innovation Solution
A method using GNSS carrier phase measurements to detect antenna movement by analyzing carrier phase residuals, providing warnings and stopping correction broadcasts when movement is detected, and optionally outputting position with error evaluations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential navigation systems use fixed base stations to improve position accuracy, then position determination accuracy for mobile rovers is improved, but the system becomes vulnerable to accuracy loss when base stations move unexpectedly
Solution Approach 1:
The system continuously monitors carrier phase measurements from the base station and compares them against expected values. When movement is detected through carrier phase residual analysis, the system generates alerts and stops correction broadcasts, creating a feedback loop that maintains system reliability while preserving measurement precision
Solution Approach 2:
Carrier phase measurements serve as an intermediary indicator to detect base station movement. Instead of directly monitoring physical movement, the system uses carrier phase residuals as a mediator to infer unauthorized motion, enabling indirect detection that preserves both accuracy and reliability
2Ease of operation
If base stations are left unattended to reduce operational complexity, then ease of operation is improved, but the risk of unauthorized movement and theft increases
Solution Approach 1:
The base station system monitors itself for movement using carrier phase measurements without requiring external surveillance. The automated detection and alerting mechanisms enable the system to self-protect against unauthorized movement, maintaining ease of operation while reducing vulnerability to theft and relocation
3Measurement precision
If carrier phase measurements are used to detect motion, then measurement precision for detecting base station movement is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The system extracts motion detection capability from complex physical sensors and implements it through signal processing of existing carrier phase measurements. By taking out the motion detection function and implementing it through mathematical analysis of GNSS signals rather than additional hardware, the system achieves high precision while limiting complexity increase
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
Ensures accurate and reliable position determination by detecting and responding to base station movements, preventing accuracy loss and enabling tracking of stolen devices.
Implementation Method 1
The receiver measures the time delays of the received signals relative to a local reference clock, or oscillator
Implementation Method 2
Carrier phase measurements along with code phase measurements are a part of raw measurement data, generated by the receiver
Data Source
AI summary
Method for detecting motion of an object using GNSS signals, including (i) measuring distances between a GNSS antenna and GNSS satellites with carrier phases at a first time; (ii) computing distances between known positions of antenna and satellites at first time; (iii) for each satellite, calculating first set of residuals=distances in (i)−distances in (ii); (iv) measuring distances between antenna and satellites with carrier phases at a second time; (v) computing distances between known positions of antenna and satellites at second time; (vi) for each satellite, calculating second set of residuals=distances in (iv)−distances in (v); (vii) differencing first and second sets of residuals; (viii) computing a metric based on set of differences in (vii); (ix) comparing metric to a threshold; (x) based on comparison in (ix), determining if object moved or possibly moved between first time and second time.