Interferometric Timing Distribution with Precision Phase Detector
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Solution Overview
Problem
Conventional timing distribution methods in networks face challenges in maintaining precise synchronization across remote destinations, particularly in space networks, where environmental factors like temperature, radiation, and path length variations cause signal skew, limiting the accuracy of timing signal delivery.
Innovation Solution
Adapting Absolute Distance Interferometry (ADI) to electrical systems for precise timing distribution, using a 100 MHz square wave signal with a skew limit of ±312.5 ps, and implementing a precision phase detector to measure path lengths and adjust timing signals, ensuring simultaneous delivery of clock signals across all hosts within a predetermined skew tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional timing distribution methods are used in networks, then the system is simple to implement, but the timing precision deteriorates due to signal skew caused by environmental factors and path length variations
Solution Approach 1:
The patent replaces conventional electrical timing distribution with optical interferometry to measure path lengths. By using light waves instead of electrical signals for measurement, the system achieves much higher precision in determining propagation delays, enabling timing synchronization at the picosecond level despite network complexity
Solution Approach 2:
The patent introduces an optical interferometer as an intermediary measurement device between the timing source and network nodes. This interferometer measures the optical path length to determine the electrical propagation delay, serving as a mediator that enables precise timing distribution without directly modifying the electrical signal transmission
2Measurement precision
If path length variations are compensated for in timing distribution, then timing accuracy improves, but the difficulty of measuring and detecting path lengths increases
Solution Approach 1:
The patent uses optical interferometry to measure path lengths instead of conventional electrical measurement methods. The optical approach provides significantly higher resolution and accuracy in measuring propagation delays, enabling the system to detect and compensate for path length variations at the picosecond level
Solution Approach 2:
The patent changes the measurement parameter from direct electrical signal analysis to optical path length measurement. By measuring the optical path length and converting it to an equivalent electrical propagation delay, the system can accurately characterize and compensate for timing variations across the network
3Reliability
If environmental factors like temperature and radiation are accounted for in timing distribution, then reliability improves, but the complexity of compensating for these factors increases
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors timing variations and environmental conditions, then adjusts the timing distribution accordingly. By measuring actual propagation delays and comparing them with expected values, the system can compensate for environmental effects and maintain synchronization reliability
Solution Approach 2:
The patent performs preliminary measurement of path lengths and environmental characteristics during system initialization or calibration phases. By characterizing the network topology and environmental conditions in advance, the system can pre-compensate for timing variations and improve reliability without requiring complex real-time adjustments
Data Source
AI summary
A method distributing data in a network is provided. The method comprises measuring the path lengths between a reference clock and a plurality of remote destinations and sending a timing signal from the reference clock to the plurality of remote destinations. The method further comprises measuring the phase between the reference clock and a return signal from each of the plurality of remote destinations and adjusting the phase of the data such that each remote destination receives the data within a skew tolerance.