Ionospheric Disturbance Mapping for Scintillation-Aware NSS Positioning
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Solution Overview
Problem
Existing navigation satellite systems (NSS) face limitations in positioning accuracy due to ionospheric disturbances, which degrade signal quality, reduce the accuracy of ionospheric models, and compromise positioning performance.
Innovation Solution
Generation and transmission of ionospheric disturbance information, including link-specific ionospheric disturbance levels, to mitigate the effects of ionospheric scintillation and gradients, allowing NSS receivers and processing entities to adapt their models or observations to improve positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If carrier phase measurements are used for positioning, then position precision is improved (centimeter- to millimeter-level), but the integer ambiguity problem arises making unambiguous range determination difficult
Solution Approach 1:
The patent uses an intermediary reference network (GNSS reference stations with known positions) to resolve the integer ambiguity problem. The reference stations compute carrier phase ambiguities and transmit correction data to users, acting as a mediator that enables precise positioning without requiring users to solve the complex ambiguity resolution problem independently.
Solution Approach 2:
The system implements feedback by continuously monitoring carrier phase measurements at reference stations, computing ambiguity corrections, and transmitting these corrections back to users in real-time. This feedback loop enables maintaining fixed-ambiguity solutions and achieving centimeter- to millimeter-level precision dynamically.
2Ease of operation
If code-based positioning is used, then positioning is simpler and more robust, but accuracy is limited (approximately 15 meters)
Solution Approach 1:
The patent merges code-based and carrier phase-based positioning methods. Users can fall back to code-based measurements when carrier phase signals are degraded by ionospheric disturbances, while still achieving high precision when conditions permit. This combination maintains simplicity while enabling high accuracy under favorable conditions.
Solution Approach 2:
The system dynamically switches between code-based and carrier phase-based positioning methods based on signal quality and ionospheric conditions. When ionospheric disturbances are detected, the system transitions to more robust code-based measurements; when conditions are favorable, it utilizes precise carrier phase measurements for centimeter- to millimeter-level accuracy.
3Measurement precision
If ionospheric disturbance mitigation is implemented, then positioning accuracy is improved, but system complexity and computational requirements increase
Solution Approach 1:
The reference stations perform self-service by autonomously monitoring their own carrier phase measurements, computing ionospheric delay corrections based on their known positions, and generating correction data without requiring external intervention. This self-service approach simplifies the overall system architecture while maintaining high positioning accuracy.
Solution Approach 2:
The reference stations perform preliminary computations of ionospheric corrections in advance, before users need the corrected positioning data. By pre-computing ambiguity corrections and ionospheric delay estimates at known reference locations, the system reduces the computational burden on user receivers and enables faster, more accurate positioning.
Data Source
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AI summary
Some embodiments pertain to generating, transmitting, and using ionospheric disturbance information applicable to at least a part (204) of the Earth's surface (202). The ionospheric disturbance information is transmitted (s50, s70) in the form of at least one message comprising reference point ionospheric disturbance levels, i.e. levels associated with a plurality of reference points (216) on a reference ionospheric shell (214). On the receiver side, an estimator is operated (s60), and, for each of at least one NSS signal observed by a NSS receiver, the reference point ionospheric disturbance levels are used to decide whether to adopt some ionospheric disturbance mitigation measures in the context of estimating parameters useful to determine a position. The ionospheric disturbance information may for example comprise ionospheric amplitude scintillation information, ionospheric phase scintillation information, and/or ionospheric gradient information. Systems, vehicles, and computer programs are also disclosed.