GNSS Differential Code Bias Correction for Limited Reference Stations
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Solution Overview
Problem
Existing methods for providing differential code bias (DCB) corrections in global navigation satellite systems (GNSS) are inefficient when limited reference stations are available, particularly for signals that are not freely measurable, leading to reduced reliability and accuracy in positioning.
Innovation Solution
A method that determines primary and secondary differential code biases using a common signal, allowing for improved accuracy and reliability by leveraging information from a larger number of reference stations, even when only a reduced number of stations are available for certain signals, through a central computation unit that processes data from multiple stations and disseminates corrections via satellite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DCBs are estimated separately for each signal combination using limited reference stations, then signal-specific accuracy is maintained, but the number of available reference stations is insufficient leading to reduced reliability
Solution Approach 1:
The DCB estimation problem is segmented into two hierarchical levels: (1) primary DCB estimation for public signals using all available reference stations, and (2) secondary DCB estimation for non-public signals using the primary DCBs as a foundation. This segmentation allows each level to utilize the appropriate subset of reference stations while maintaining overall reliability.
Solution Approach 2:
The primary DCB serves as an intermediary that bridges the gap between limited reference station availability and the need for accurate DCB estimation for non-public signals. By using the primary DCB (derived from public signals with extensive reference station coverage) as a reference, the system can estimate secondary DCBs for non-public signals even when few reference stations track those signals.
2Measurement precision
If separate DCB estimation is performed for each signal combination, then signal-specific accuracy is achieved, but computational effort increases significantly
Solution Approach 1:
The computational task is segmented hierarchically: first estimate primary DCBs for public signal combinations using all reference stations, then estimate secondary DCBs for non-public signal combinations using the primary DCBs as a base. This reduces the overall computational burden compared to estimating all DCBs independently from scratch.
Solution Approach 2:
The primary DCB estimation is performed as a preliminary action before estimating secondary DCBs. The primary DCBs, which are more reliably estimated due to broader reference station coverage, are computed first and then used to facilitate the estimation of secondary DCBs, reducing the computational effort required for the second stage.
3Reliability
If more reference stations are deployed to improve DCB estimation for non-public signals, then reliability improves, but system complexity and costs increase
Solution Approach 1:
The primary DCB estimation system serves multiple functions: it provides accurate DCB values for public signals and simultaneously serves as a foundation for estimating DCBs for non-public signals. This multi-functionality allows the system to maintain reliability for non-public signals without requiring dedicated reference stations for each signal type.
Solution Approach 2:
The system copies the successful approach of public signal DCB estimation (which benefits from extensive reference station coverage) and applies it to non-public signals through the secondary DCB estimation process. By using the primary DCB as a template or reference, the system achieves reliable estimation for non-public signals without needing the same level of reference station infrastructure.
Data Source
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AI summary
A method for providing a differential code bias (DCB), in particular a primary differential code bias (DCB1) and a secondary differential code bias (DCB2), in a global navigation satellite system using satellites (2) communicating by using at least • - a first signal (41) and an additional first signal (41') both having a first carrier frequency (C1) and • - a second signal (42) and an additional second signal (42 ') both having a second carrier frequency (C2); wherein a primary differential code bias (DCB1) for the first signal (41) and the second signal (42) is determined and wherein the primary differential code bias (DCB1) is used for determining, and in particular providing, a secondary differential code (DCB2) bias for the additional first signal (41') and the additional second signal (421).