Rational Number Filtering for Stable PTP Time Distribution
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Solution Overview
Problem
Conventional digital time processing systems over time-sensitive networks (DTP TSN) face challenges in accurately distributing time due to phase noise and quantization errors, leading to instability and increased costs in synchronization solutions.
Innovation Solution
The implementation of a Rational Number Filter (RNF) and a Digital Time Processing (DTP) system that uses open or closed loop phase control, combined with a Time to Digital Converter (TDC) and Digital to Time Converter (DTC), to filter out phase noise and produce a timing implementing signal from a free-running local clock, preventing accumulation of digital quantization errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional digital time processing systems are used, then time distribution can be implemented, but phase noise and quantization errors accumulate leading to instability
Solution Approach 1:
The patent replaces conventional mechanical/time-based filtering methods with a Rational Number Filter that uses rational number arithmetic to eliminate quantization errors. The RNF uses a transfer function with rational coefficients to filter phase noise while maintaining exact arithmetic representation, preventing error accumulation that plagues conventional systems.
Solution Approach 2:
The patent changes the mathematical representation from floating-point or fixed-point arithmetic to rational number arithmetic. By representing time intervals and filter coefficients as ratios of integers, the system maintains precision without quantization errors while still achieving phase noise filtering through the rational transfer function.
2Measurement precision
If high-precision timing solutions are implemented, then time distribution accuracy improves, but system complexity and costs increase
Solution Approach 1:
The patent replaces complex hardware-based precision timing systems with a software/mathematical approach using rational number filters. The RNF can be implemented in firmware or software, eliminating the need for expensive, complex hardware while maintaining or improving precision through exact rational arithmetic.
Solution Approach 2:
The patent uses computationally simple rational number operations that can be implemented with basic digital logic or software, replacing expensive precision timing hardware. The rational number filter uses simple integer arithmetic operations that are computationally inexpensive and can be implemented in resource-constrained environments.
Data Source
AI summary
The Digital Time Processing using Rational Number Filters (DTP RNF) disclosed herein is contributing methods, systems and circuits for using a Precision Time Protocol (PTP) such as IEEE 1588 for distributing a master time secured by a master unit to slave units by utilizing slave clocks, synchronous to referencing frames communicated with PTP messages or compatible with them data receiver clocks, for maintaining a local slave time which is increased to a local master time by adding to it an estimate of a transmission delay derived by processing PTP messages or by other means, wherein such distribution of the master time includes filtering out phase noise of the timing referencing signals with the Rational Number Filters in order to produce accurate and stable timing implementing signals such as the slave clock, local slave time and local master time.