LXI Instrument Clock Synchronization via PTP Timestamps
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Solution Overview
Problem
Existing test systems face challenges in synchronizing measurements across multiple instruments, such as LXI function generators and digital multimeters, to ensure simultaneous data collection without phase errors, particularly when dealing with stimulus signals applied to a device-under-test.
Innovation Solution
A method for synchronizing state transitions in a group of devices connected via a communication network, where an initiating device sends messages with state transition times, allowing responding devices to coordinate their actions based on the longest time interval required for all devices to transition, ensuring precise timing for tasks like voltage and current measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple LXI instruments are used for simultaneous measurements, then measurement capability is improved, but clock synchronization accuracy deteriorates
Solution Approach 1:
The system uses IEEE 1588 PTP protocol to establish a distributed feedback mechanism where time-stamped messages are exchanged between instruments. The function generator sends trigger messages with precise timestamps to DMMs, and the system continuously monitors and adjusts clock offsets based on measured time differences, achieving sub-50ns synchronization accuracy across multiple instruments.
Solution Approach 2:
The patent introduces a time synchronization intermediary mechanism using multicast message passing and PTP protocol entities. These intermediaries mediate the time coordination between the function generator and multiple DMMs, translating local clock times into synchronized reference times that all instruments can use for simultaneous measurements.
2Device complexity
If DMMs make measurements at different times, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The function generator performs preliminary actions by sending trigger messages with predetermined state transition times to all DMMs before measurements are taken. This preliminary time coordination ensures that all instruments transition to their measurement states simultaneously at the exact moment when voltage and current measurements are required, eliminating timing discrepancies without adding complex coordination hardware.
3Ease of operation
If state transitions are not synchronized, then ease of operation is improved, but reliability of synchronized operations deteriorates
Solution Approach 1:
The patent implements a universal time reference mechanism using IEEE 1588 PTP protocol that serves multiple functions simultaneously: it provides individual device operation autonomy, coordinates state transitions across instruments, and enables simultaneous measurements. The time synchronization system acts as a multi-functional intermediary that maintains device independence while ensuring reliable synchronized operations when needed.
Data Source
AI summary
A method of synchronizing respective state transitions in a group of devices including at least one responding device is disclosed. The group of devices is communicatively coupled to an initiating device via a communication network. The method includes the at least one responding device receiving a trigger message from the initiating device. The trigger message includes a state transition time or a time from which a state transition time is obtainable. The method further includes the at least one responding device jointly making a respective state transition at the state transition time. A responding device, and a system including the initiating device and the responding device are also disclosed.