Coarse and Fine-Phase Timing for Asynchronous Trigger Precision
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Solution Overview
Problem
Existing digital timing devices face challenges in achieving precise duration measurements between asynchronous triggers due to inaccuracies caused by asynchronous arrival of triggers relative to clock signals, leading to potential errors of up to one coarse clock cycle.
Innovation Solution
The solution involves a timing device with a coarse timer and phase indicators that provide corrections to the coarse duration measurement by using a coarse clock signal and a fine clock signal, where the fine clock signal is synchronized with the coarse clock, allowing for precise timing by accounting for the phase of trigger arrivals within the coarse clock cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coarse clock signal is used for duration measurement, then the distribution of high-frequency clock signals is minimized, but the measurement precision deteriorates due to asynchronous trigger arrival times
Solution Approach 1:
The timing measurement function is segmented into two parts: a coarse timer that measures the integer number of clock cycles, and phase indicators that measure the fractional phase within the clock cycle. This segmentation allows the system to achieve high precision without requiring a uniformly distributed high-frequency clock signal across all measurement points.
Solution Approach 2:
Phase indicators act as intermediaries that capture the phase information of asynchronous triggers relative to the clock signal. These phase measurements serve as correction values that bridge the gap between the coarse clock cycle count and the actual trigger timing, enabling precise measurement without complex high-frequency clock distribution.
2Measurement precision
If the coarse clock frequency is increased to improve precision, then measurement precision improves, but the distribution of high-frequency clock signals increases
Solution Approach 1:
The measurement system segments the timing function into coarse cycle counting and fine phase measurement. This allows the use of a lower-frequency coarse clock for the majority of the measurement function, reducing energy consumption, while still achieving high precision through the additive phase correction mechanism.
Solution Approach 2:
The system changes the parameter of clock frequency from a single high value to a combination of a lower coarse frequency and phase offset information. This parameter transformation maintains measurement precision while significantly reducing the energy required for clock signal generation and distribution.
3Measurement precision
If phase indicators are added to correct coarse measurements, then measurement precision improves, but device complexity increases
Solution Approach 1:
Phase indicators serve as simple intermediary components that capture phase information without requiring complex circuitry. Each phase indicator merely needs to detect the relative phase of a trigger signal with respect to the clock signal, producing a correction value that is added to the coarse measurement. This intermediary approach achieves high precision with minimal added complexity.
Solution Approach 2:
The phase indicators and coarse timer work together in a self-service manner where the phase indicators provide correction values that automatically compensate for the quantization error inherent in coarse timing. The system uses its own internal clock signal and simple phase detection to generate the necessary corrections without requiring external calibration or complex control mechanisms.
Data Source
AI summary
A high-precision measurement of a duration is calculated from a coarse duration measurement and at least one trigger-phase measurement.