Hybrid Pseudorange Position Fix for Satellite Navigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Navigation satellite systems (NSS) face challenges in achieving accurate position fixes due to limitations in satellite geometry and signal quality, particularly when high accuracy receivers cannot obtain sufficient pseudorange data, leading to incomplete or inaccurate position solutions.
Innovation Solution
The implementation of a hybrid pseudorange solution that combines data from high yield (HY) and high accuracy (HA) receivers, using HY pseudoranges when HA pseudoranges are unavailable, to generate a hybrid position fix, which includes a hybrid module that processes measurements from both types of receivers to provide a 'best available' solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high accuracy receivers are used to obtain pseudorange data, then position determination accuracy is improved, but position determination availability deteriorates when satellite geometry is insufficient
Solution Approach 1:
The patent combines pseudorange data from high accuracy receivers and high yield receivers into a hybrid solution. When high accuracy receivers cannot obtain sufficient pseudorange data due to satellite geometry limitations, the system merges in pseudorange data from high yield receivers to maintain position determination availability while striving to preserve accuracy through selective data incorporation.
Solution Approach 2:
The system dynamically changes the parameters used for position determination by switching between high accuracy pseudorange data and high yield pseudorange data based on availability. It adjusts the data source parameters according to satellite geometry conditions, using high yield data as a fallback when high accuracy data is insufficient, thereby resolving the contradiction between accuracy and availability.
2Reliability
If high yield pseudoranges are used to improve position determination availability, then measurement precision deteriorates
Solution Approach 1:
The patent applies local quality by selectively using high yield pseudorange data only in specific situations where high accuracy data is unavailable. Rather than uniformly using high yield data, the system locally incorporates it only where needed to maintain availability, thereby minimizing the impact on overall measurement precision while resolving the availability issue.
3Reliability
If manual mask settings are used to filter raw measurements, then position computation reliability is improved, but operation complexity increases
Solution Approach 1:
The system implements self-service by automatically adjusting mask settings based on the available raw measurements without requiring manual user configuration. The receiver autonomously determines appropriate elevation and signal-to-noise ratio masks to filter measurements, thereby improving position computation reliability while eliminating the operational complexity of manual mask setup.
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 approach enables the generation of a sufficiently accurate position fix even when high accuracy solutions are not possible with HA pseudoranges alone, improving position determination accuracy and availability by leveraging HY pseudorange data to enhance geometric strength and reduce errors.
Implementation Method 1
each of the orbiting GPS satellites broadcasts spread spectrum microwave signals encoded with positioning data and satellite ephemeris information
Implementation Method 2
determine the time of flight from satellite to receiver by synchronizing a local replica of the satellite signal and determining the time of flight of this signal, compare it to the time of transmission
Implementation Method 3
Multiplying this by the speed of light gives what is termed the pseudorange measurement of that satellite
Data Source
AI summary
Raw measurements for a plurality of GNSS satellites are pruned based on signal to noise ratio (SNR) and elevation; with remaining unpruned raw measurements sorted by SNR into a sorted list of raw measurements. A first dilution of precision (DOP) based selecting process is performed to select an initial candidate list of raw measurements. The first DOP selecting process begins by using at least those of said pruned list of raw measurements which exceed an SNR quality threshold. The initial candidate list of raw measurements is sorted by elevation angle. A second DOP selecting process is performed to select a final candidate list of raw measurements. The second DOP selecting process begins by using at least those of the sorted initial candidate list which an elevation quality threshold. The final candidate list is used in position computation for a present epoch.