Terrain Database Segmentation for Mobile GPS Altitude Accuracy
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Solution Overview
Problem
Existing GPS position determination systems face challenges in accurately determining altitude, especially in environments with limited satellite visibility or poor geometry, and require substantial memory resources for terrain elevation data, making them impractical for mobile devices.
Innovation Solution
A method using a defined terrain database with expected user altitudes for specific populated areas, reducing memory requirements and enhancing GPS positioning speed and accuracy by providing localized altitude aiding within mobile devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a comprehensive terrain elevation database covering the entire earth is used, then altitude determination accuracy is improved, but memory requirements increase substantially making it impractical for mobile devices
Solution Approach 1:
The patent divides the comprehensive terrain database into multiple regional segments, each covering specific geographic areas. The mobile device loads only the relevant regional data based on its current location, rather than storing the entire earth's terrain database. This segmentation approach maintains high altitude determination accuracy for the operational area while dramatically reducing memory requirements.
Solution Approach 2:
The patent implements local quality by providing terrain elevation data with varying levels of detail and coverage based on local requirements. High-resolution terrain data is provided for areas where the device operates, while minimal or no data is stored for areas where the device does not operate. This allows the system to optimize between measurement precision and memory usage dynamically.
2Measurement precision
If worldwide terrain elevation data is stored on a server, then comprehensive altitude information is available, but the data volume is too large to be practically stored on mobile stations
Solution Approach 1:
The patent extracts only the necessary terrain elevation data for the mobile device's current operational area from the comprehensive worldwide database. By using location-based filtering and regional data selection, the system extracts minimal required data from the server, significantly reducing the data volume that needs to be stored on the mobile device while maintaining complete altitude information for the operational region.
Solution Approach 2:
The patent implements preliminary action by pre-loading terrain data for expected operational areas into the mobile device before actual positioning operations begin. This allows the device to have comprehensive altitude information readily available for the areas it will operate in, without requiring storage of the entire worldwide database. The preliminary data loading occurs based on predicted or historical usage patterns.
3Ease of operation
If fixed altitude mode is used for maritime GPS receivers, then altitude determination is simplified, but the method cannot address general position determination over uneven and unknown terrain
Solution Approach 1:
The patent implements dynamics by transitioning from a static fixed altitude mode to a dynamic terrain-adaptive mode. The system automatically adjusts its altitude determination method based on the operational environment: using simplified fixed altitude for maritime environments where appropriate, and switching to terrain-based altitude determination for land areas with varying elevation. This dynamic adaptation maintains ease of operation while significantly improving terrain versatility.
Solution Approach 2:
The patent applies parameter changes by modifying the altitude determination parameters based on the operational context. In maritime environments, the system uses a fixed altitude parameter (sea level), while in terrestrial environments, it dynamically changes to terrain-elevation-based parameters. This parameter adaptation allows the system to maintain simplicity in appropriate environments while achieving versatility in challenging terrain conditions.
Data Source
AI summary
A method and apparatus for using a predetermined portion of terrain elevation maps in a database for aiding in computing a three-dimensional position of a wireless station. Instead of using the entire terrain model of the earth or an entire country, the database consists of an incomplete model, which includes only the most populous areas or specific regions. This reduces the size of the information in the database, which in turn reduces the amount of time to compute the positions of the wireless device.