RF Beacon Two-Way Time Transfer Clock Synchronization
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Solution Overview
Problem
Synchronizing the local time of beacons in terrestrial positioning systems is challenging, especially in urban and indoor environments, due to difficulties in achieving network-wide and cost-effective clock synchronization, which affects positioning accuracy and can have critical consequences such as delayed emergency responses.
Innovation Solution
A method and system for synchronizing beacons using two-way time transfer, where beacons transmit and receive timing signals to each other, allowing them to synchronize their local clocks based on measured transmission and reception times, and optionally synchronizing with a network clock using a remote timing source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a centralized source provides time synchronization RF signals to each beacon, then clock synchronization accuracy is improved, but system cost and complexity increase
Solution Approach 1:
Each beacon independently determines its clock offset by receiving timing signals from other beacons and calculating the difference between transmitted and received times. This self-synchronization approach eliminates the need for a centralized synchronization source, reducing system complexity while maintaining synchronization accuracy through distributed peer-to-peer time transfer.
Solution Approach 2:
The centralized synchronization system is segmented into distributed beacon pairs that independently perform time transfer. Instead of one central authority synchronizing all beacons, each beacon pair autonomously establishes their relative time offset, dividing the synchronization function across multiple independent units and reducing central system complexity.
2Measurement precision
If beacons transmit and receive timing signals to each other for synchronization, then positioning accuracy is improved, but signal processing complexity increases
Solution Approach 1:
The beacon hardware is designed to perform both transmission and reception functions using the same RF front-end and baseband processing chain. The signal router selectively connects the antenna to either the transmitter or receiver based on operational mode, allowing a single multi-functional device to handle both signal generation and signal acquisition, thereby improving positioning accuracy without proportionally increasing processing complexity.
Solution Approach 2:
The beacon system dynamically switches between transmission and reception modes using a signal router controlled by a mode indicator. This dynamic reconfiguration allows the same hardware resources to be flexibly allocated based on operational requirements, enabling accurate two-way time transfer for positioning while optimizing resource utilization and managing processing complexity through time-division multiplexing.
Data Source
AI summary
Synchronizing the local time of beacons using two way time transfer methods and hardware enabling such methods. Certain systems incorporate receive hardware into beacon circuitry used for transmitting signals so that the beacon can transmit RF signals during transmission periods, and can also receive RF signals from other beacons during non-transmission periods. Receive hardware may be incorporated into beacon circuitry such that the beacon receives an incoming signal and passes that incoming signal to a digital pre-distortion linearization module, which can process that received signal. Methods for controlling whether a beacon transmits RF signals or receives RF signals are also discussed, as are methods for using RF signals received from other beacons for synchronization.