DGPS Asset Tracking System for Marine Terminals
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Solution Overview
Problem
Current location systems for tracking assets in marine terminals face challenges in accuracy and efficiency, particularly due to errors in GPS systems such as ionospheric effects and satellite position errors, which are not adequately addressed by existing technologies.
Innovation Solution
The integration of a Real-Time Location System (RTLS) with Differential Global Positioning System (DGPS) enhancements, using a processor to determine first-to-arrive signals and cache GPS data for efficient data transmission, minimizes packet collisions and latency, and provides accurate location tracking through a network processor and roving receiver units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If GPS systems are used for location tracking, then coverage area is improved, but measurement precision deteriorates due to ionospheric effects and satellite position errors
Solution Approach 1:
The patent introduces DGPS ground-based reference stations as intermediary elements that receive GPS signals and generate correction data. These reference stations act as mediators between the satellite system and the mobile receivers, providing corrected position information that eliminates ionospheric effects and satellite ephemeris errors while maintaining wide coverage through the network of reference stations.
Solution Approach 2:
The system implements feedback by using fixed ground-based reference stations with known precise positions to continuously monitor GPS signal errors. The correction data generated from these reference stations is fed back to mobile receivers in real-time, allowing them to compensate for ionospheric delays and satellite position errors, thereby improving location accuracy without sacrificing coverage area.
2Measurement precision
If real-time location tracking is implemented with multiple access points, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the location tracking system into distinct functional segments: DGPS reference stations for correction data generation, access points for signal reception, and mobile receivers for position calculation. This segmentation allows each component to perform its specific function efficiently, improving overall measurement precision while managing system complexity through modular architecture.
Solution Approach 2:
The access points in the system serve multiple functions: they receive GPS signals from mobile receivers, collect correction data from DGPS reference stations, and facilitate position calculation. This multi-functionality reduces the need for separate dedicated components, thereby improving measurement precision without proportionally increasing device complexity.
3Reliability
If GPS data is transmitted in real-time from mobile receivers, then reliability is improved, but loss of time increases due to packet collisions and latency
Solution Approach 1:
The patent implements preliminary action by having mobile receivers cache GPS data locally before transmission. This pre-caching allows the system to prepare data in advance, reducing the critical impact of packet collisions and transmission delays. When transmission occurs, the cached data is ready for immediate transfer, improving reliability while minimizing additional time loss.
Solution Approach 2:
The system employs periodic data transmission intervals rather than continuous real-time transmission. Mobile receivers collect GPS data periodically and transmit cached data at scheduled intervals, which reduces packet collisions on the communication channel. This periodic action maintains data transmission reliability while significantly reducing latency compared to continuous transmission attempts.
Data Source
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AI summary
A location system for tracking assets within a terminal includes a Differential Global Positioning System (DGPS) reference receiver within the terminal that receives GPS signals and generates DGPS correction data. In one aspect, a roving receiver unit is carried by an asset to be tracked within the terminal. It includes a GPS receiver that receives GPS signals and the DGPS correction data from the DGPS reference receiver. A tag transmitter transmits a wireless RF signal containing GPS location data based on received GPS signals and DGPS correction data. At least one access point is positioned within the terminal for receiving the wireless RF signal from the tag transmitter. A processor is operatively connected to the at least one access point for receiving GPS location data and determining a location of the asset to be tracked.