Dynamic Satellite Grouping for Rapid Position Fix
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Solution Overview
Problem
Conventional satellite search methods in satellite communication systems, such as GPS, require a lengthy time-to-first-fix (TTFF) due to sequential searching of all possible satellites, making it inefficient to identify the necessary four satellites for a three-dimensional position fix.
Innovation Solution
The method involves forming and dynamically updating groups of satellites based on scanning times, hit numbers, and priorities, allowing for parallel searching of the most probable visible satellites, thereby reducing the search range and time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential searching of all possible satellites is used, then comprehensive satellite coverage is achieved, but time-to-first-fix increases significantly
Solution Approach 1:
The patent divides the satellite search process into multiple stages: initial rapid search using almanac data to identify candidate satellites, followed by detailed ephemeris-based search only for those candidates. This segmentation reduces the overall search space and time-to-first-fix while maintaining complete satellite coverage.
Solution Approach 2:
The patent performs preliminary satellite identification using almanac data before conducting the full ephemeris-based search. This preliminary action filters out invisible satellites early, so that only promising candidates require detailed searching, significantly reducing time-to-first-fix without compromising search completeness.
2Measurement precision
If all possible code phases and Doppler frequencies are scanned, then accurate satellite identification is achieved, but search time increases
Solution Approach 1:
The patent dynamically adjusts the search strategy based on available information. Initially, broader searches are conducted using almanac data with coarser resolution. Once candidate satellites are identified, the search transitions to finer ephemeris-based tracking with precise code phase and Doppler frequency estimation, optimizing both accuracy and time efficiency at each stage.
Solution Approach 2:
The patent changes search parameters (code phase range, Doppler frequency range, integration time) based on the search stage and available satellite information. Coarse parameter scanning is used initially to identify candidates, then parameters are refined and narrowed for detailed acquisition, reducing total scanning time while maintaining detection accuracy.
3Productivity
If multiple physical channels are used for parallel search, then search speed increases, but device complexity increases
Solution Approach 1:
The patent segments the satellite search task across multiple channels in parallel, with each channel dedicated to searching specific candidate satellites identified from almanac data. This segmentation enables simultaneous processing of multiple candidates, increasing search rate while keeping each individual channel relatively simple and manageable.
4Quantity of substance
If sequential satellite search is used, then resource requirements are minimized, but search efficiency decreases
Solution Approach 1:
The patent performs preliminary filtering of satellite candidates using almanac data before initiating resource-intensive ephemeris-based searches. This preliminary action ensures that computational and hardware resources are concentrated only on promising candidates, improving search efficiency (reducing time-to-first-fix) without requiring proportionally more resources.
Data Source
AI summary
A method for searching satellites is disclosed. In the method of the present invention, the satellites are selected to consist of a group, and searching is conducted in this group. The group size is predetermined for each stage so as to be the most appropriate for various searching conditions. The member number of the group (i.e. group size) and the members of the group are updated as the searching results are continually obtained. The updates are done according to scanning times of the group, satellite hit number, searching time for the group and satellite priorities and the like, for example. The group size can be reduced or expanded. By using the method, satellites required to fix a position can be rapidly found.