Latency Compensation for Synchronized DMM Measurements
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Solution Overview
Problem
In test systems, discrepancies in clock synchronization between instruments cause latency issues, leading to asynchronous measurements during simultaneous tasks like RMS power measurement, where DMMs may not make measurements at the expected time due to propagation and software/hardware delays.
Innovation Solution
The method involves advancing the initiation of measurement tasks by device-specific latency times, allowing DMMs to adjust their execution timing to align with a predetermined time, ensuring simultaneous measurements by using IEEE 1588 clocks and execute time registers to account for latency in the measurement front-end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DMMs use standard trigger messages without latency compensation, then the system operation is simple, but measurements are not synchronized due to propagation and processing delays
Solution Approach 1:
The patent applies preliminary action by calculating and storing latency values in advance for each DMM device, then using these pre-determined values to compensate timing delays in real-time operations. The system performs timing calibration beforehand to establish device-specific latency profiles, which are then applied automatically during measurement sequences to achieve synchronized measurements without real-time complex calculations.
Solution Approach 2:
The patent changes the time parameter by adjusting trigger message timestamps based on device-specific latency values. Each DMM receives a trigger message with a modified time value that accounts for its individual processing and propagation delays, ensuring that all devices execute measurements at the intended synchronized time point rather than their respective default times.
2Measurement precision
If trigger messages include absolute time values, then measurements can be scheduled at predetermined times, but clock synchronization discrepancies between instruments cause timing errors
Solution Approach 1:
The patent implements feedback by using IEEE 1588 Precision Time Protocol to continuously monitor and adjust clock synchronization across all test instruments. The system periodically exchanges timing messages between devices to detect and correct drift, ensuring that absolute time values remain consistent and reliable across the distributed measurement system.
Solution Approach 2:
The patent adjusts the time parameter by compensating for clock synchronization discrepancies through latency calibration. The system measures actual propagation and processing delays for each device and applies corrective time offsets to trigger messages, transforming absolute time values into effective execution times that account for individual device characteristics and synchronization variations.
3Measurement precision
If DMMs process trigger messages sequentially through CPU, then the device operation is simple, but processing delays cause measurements to occur later than expected
Solution Approach 1:
The patent applies preliminary action by pre-measuring and storing the CPU processing time required for each DMM device type. These baseline latency values are determined through calibration procedures that profile the processing speed of each device's CPU and measurement front-end, allowing the system to compensate for sequential processing delays by adjusting trigger times in advance rather than requiring real-time optimization.
Data Source
AI summary
A method of executing an action at a predetermined time by a device is disclosed. The device has a latency time between initiation of the execution of the action and the actual execution of the action. The method includes advancing the initiation of the execution of the action by the latency time. A device in which the method is implemented and a system including the device are also disclosed.