GNSS Carrier Phase Integrity Monitoring via Doppler Velocity
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Solution Overview
Problem
Current GNSS satellite navigation systems face integrity issues due to undetected biases in position measurements, particularly in high-precision applications like drone navigation, where existing monitoring algorithms are limited to pseudo-distance measurements and lack real-time integrity verification using carrier phase measurements.
Innovation Solution
A method for real-time monitoring of positioning biases derived from GNSS carrier phase measurements, compatible with RTK techniques, involving steps to calculate initial position and velocity, verify integrity through doppler measurements, and resolve phase ambiguities to ensure dependable positioning, even in high-dynamics operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If carrier phase measurements are used for high-precision positioning, then positioning precision is improved, but integrity cannot be verified
Solution Approach 1:
The patent uses code pseudo-distance measurements as an intermediary to verify the integrity of carrier phase measurements. The code measurements, which have lower precision but provide integrity information through RAIM algorithms, serve as a mediator to check whether carrier phase measurements are free from biases greater than a threshold, thereby enabling integrity verification for high-precision positioning.
Solution Approach 2:
The patent applies a partial verification approach where only biases exceeding a predetermined threshold are detected, rather than attempting to detect all possible errors. This partial action allows the system to verify integrity for the most critical error cases while maintaining computational feasibility and avoiding the complexity of detecting all minor variations.
2Reliability
If only pseudo-distance measurements are used for integrity monitoring, then integrity verification is simplified, but positioning precision is limited
Solution Approach 1:
The patent merges two types of measurements with different characteristics: code pseudo-distance measurements (which provide integrity information) and carrier phase measurements (which provide high precision). By combining these measurements and using the code measurements to verify the integrity of the carrier phase measurements, the system achieves both high positioning precision and reliable integrity verification.
3Measurement precision
If protection radius is reduced for more precise positioning, then positioning precision is improved, but the risk of undetected biases increases
Solution Approach 1:
The patent performs preliminary verification of carrier phase measurement integrity using code pseudo-distance measurements and RAIM algorithms before relying on the high-precision carrier phase data for positioning. This preliminary action detects biases greater than a threshold in advance, allowing the system to use smaller protection radii with reduced risk of undetected errors affecting the positioning result.
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 method provides real-time integrity monitoring for GNSS positioning, reducing the risk of loss of integrity and enabling more precise, dependable positioning with smaller protection radii, suitable for Safety Of Life applications.
Implementation Method 1
a third step E3 of calculating the velocity of the carrier, at a plurality of observation instants, the said third step being carried out on the basis of the apparent-doppler measurements estimated on the satellite sight axes, on the basis of the satellite signals carrier phase measurements
Data Source
AI summary
Methods of checking the integrity of the estimation of the position of a mobile carrier are provided, the position being established by a satellite-based positioning measurement system, the estimation being obtained by the so-called “real time kinematic” procedures. The method verifies that the carrier phase measurement is consistent with the code pseudo-distance measurement. The method comprises a step of calculating the velocity of the carrier, at each observation instant, a step of verifying that at each of the observation instants, the short-term evolution of the carrier phase of the signals received on each of the satellite sight axes is consistent with the calculated velocity and a step of verifying that at each of the observation instants, the filtered position obtained on the basis of the long-term filtered measurements of pseudo-distance through the carrier phase is dependable.