Two-Way Time Transfer Using Communication Symbols for Precise Ranging
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Solution Overview
Problem
Existing two-way time transfer and ranging systems rely on ranging codes, which consume bandwidth, power, and time resources, and are inefficient for dynamic links with unstable clocks.
Innovation Solution
The method employs the built-in capabilities of digital transceivers to use waveform symbols as ranging and time-synchronization codes, leveraging symbol arrival times and carrier tracking loops, and optionally uses a Kalman filter for improved performance, achieving precise clock synchronization and range estimation with efficient resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ranging codes are used for time transfer and ranging, then clock synchronization and range determination can be achieved, but bandwidth, power, and time resources are consumed
Solution Approach 1:
The patent extracts the ranging function from dedicated ranging codes and implements it using existing communication waveform symbols. By removing the need for separate ranging codes and utilizing the built-in symbol timing and carrier tracking capabilities of digital transceivers, the system achieves ranging functionality without the additional power and bandwidth consumption of dedicated ranging sequences
Solution Approach 2:
The patent makes the communication waveform symbols serve multiple functions: they simultaneously carry communication data and provide ranging information. The same symbols used for data transmission are also used for two-way time transfer and range determination, eliminating the need for separate dedicated ranging codes and reducing overall resource consumption
2Measurement precision
If ranging codes are used for time transfer and ranging, then clock synchronization can be achieved, but time resources are consumed
Solution Approach 1:
The patent merges the time transfer function with the communication signal transmission. By combining clock synchronization measurements with the ongoing communication waveform symbols, the system achieves time transfer functionality without requiring separate time transfer signal exchanges, thereby reducing time resource consumption
3Measurement precision
If legacy two-way time transfer techniques are used, then ranging and clock synchronization are enabled, but bandwidth and power resources are consumed
Solution Approach 1:
The patent enables the communication waveform symbols to serve themselves for ranging purposes. By utilizing the built-in symbol timing recovery and carrier tracking loops that are already present in digital transceivers for communication, the system extracts ranging information without requiring additional dedicated ranging codes or increased bandwidth allocation
Data Source
AI summary
Some examples estimate time-varying range and clock offset between first and second transceivers that are moving relative to one another. The first transceiver transmits a first stream of symbols at a first succession of times according to a first clock, and receives from the second transceiver a second stream of symbols transmitted at a second succession of times according to a second clock. The first transceiver estimates arrival times and delays of symbols of the received second stream of symbols, and uses them to calculate first and second values describing a relationship between the estimated arrival times and delays of symbols. The first transceiver receives from the second transceiver third and fourth values describing a relationship between estimated arrival times and delays of symbols of the first stream of symbols. The first transceiver estimates the time-varying range and time-varying clock offset using the first, second, third, and fourth values.