RF Beacon Clock Synchronization for Locationing Receivers
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Solution Overview
Problem
Existing methods for synchronizing clocks in wireless communication networks for locationing objects are costly and inefficient, particularly in applications where precise time-stamping is required.
Innovation Solution
A method where local clocks in locationing receivers are synchronized using RF beacon packets transmitted by a reference transmitter at a known location, allowing for accurate time-stamping of RF packets and reducing the need for a single highly accurate stable clock, thereby decreasing costs and improving locationing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single highly accurate stable clock is distributed via coax or RF broadcast to synchronize locationing receivers, then time synchronization accuracy is improved, but system cost increases significantly
Solution Approach 1:
The patent replaces expensive, highly stable clock distribution infrastructure with inexpensive RF beacon packets that are transmitted periodically. Each locationing receiver uses its own local clock, which is much cheaper than the alternative of distributing a single highly accurate clock through coax or RF broadcast systems.
Solution Approach 2:
The patent introduces RF beacon packets as an intermediary mechanism to enable time synchronization. These beacon packets serve as a common reference that all locationing receivers can use to synchronize their local clocks, eliminating the need for direct physical or RF broadcast clock distribution while achieving the necessary synchronization accuracy.
2Device complexity
If local clocks at each locationing receiver are used without synchronization, then system cost decreases, but time measurement uncertainty increases
Solution Approach 1:
The patent implements a feedback mechanism where locationing receivers compare their local clock timestamps against the known transmission time of RF beacon packets. This feedback allows each receiver to adjust and synchronize its local clock, ensuring that despite using inexpensive independent clocks, the time measurement uncertainty remains low through continuous calibration against the beacon reference.
Solution Approach 2:
The patent performs preliminary clock synchronization by having locationing receivers align their local clocks with the RF beacon packet transmission times before actual locationing measurements are taken. This preliminary action ensures that when locationing measurements occur, the clocks are already synchronized, reducing time measurement uncertainty without requiring expensive ongoing synchronization infrastructure.
Data Source
AI summary
A method and apparatus for locationing an object in a communication network. The method includes transmitting by a wireless transceiver fixed to the object of unknown location a plurality of radio frequency (RF) packets to a plurality of locationing receivers (LRs) in the communication network. The method further includes determining by each locationing receiver the local time of arrival of the RF packet and places a time stamp on the received RF packet based on a corresponding local clock, wherein the local clocks of the locationing receivers are synchronized based on a plurality of RF beacon packets transmitted by at least one reference transmitter at a known location.