Metrology Radio Communications System Clock Synchronization
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Solution Overview
Problem
Frequency hopping spread spectrum (FHSS) communication systems used in machine tool measurement probes face metrology accuracy issues due to real-time clock adjustments, which can introduce timing errors when communicating asynchronous measurement events.
Innovation Solution
A frequency hopping radio communications system where the measurement station transmits timing information relative to its clock, and the interface station generates a measurement output taking into account periodic clock adjustments to maintain synchronization, ensuring accurate timing without degrading metrology accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic clock adjustment is performed to maintain synchronization between measurement station and interface station, then communication reliability is improved, but measurement precision deteriorates due to timing errors in asynchronous measurement events
Solution Approach 1:
The interface station performs clock adjustments in advance of processing measurement events, and the measurement station records the timing of these adjustments. This preliminary action allows the system to maintain synchronization while preserving accurate timing relationships for measurement events, as the clock state at the time of each measurement can be determined without being affected by subsequent adjustments.
Solution Approach 2:
The patent introduces an intermediary mechanism where the measurement station records timing information relative to its own clock, and the interface station uses recorded clock adjustment data to translate this timing information into accurate timestamps. This intermediary approach decouples the synchronization function from the measurement timing function, allowing both to coexist without interference.
2Reliability
If real-time clock adjustment is performed to maintain frequency hopping synchronization, then communication robustness is improved, but timing accuracy of measurement events deteriorates
Solution Approach 1:
The system records clock adjustment information in advance and uses this recorded information to accurately determine the timing of measurement events. By performing the clock adjustment tracking preliminarily and using it to correct timing calculations, the system maintains both synchronization robustness and timing accuracy without one compromising the other.
Solution Approach 2:
The measurement station sends feedback to the interface station about its clock state and received measurement events. The interface station uses this feedback along with recorded clock adjustment data to accurately calculate timestamps, creating a closed-loop system that maintains both synchronization and timing precision.
Data Source
AI summary
A frequency hopping radio communications system includes a measurement station having a first clock and an interface station having a second clock. The measurement station transmits measurement information from a measurement event. The measurement information includes timing information relating the measurement event to the first clock. The interface station receives the measurement information and generates a measurement output including timing information relative to the second clock. One of the first and second clocks is designated as a master clock and a periodic clock adjustment of the other is performed to maintain synchronisation with the designated master clock. The timing information of the measurement output generated by the interface station takes into account any of the periodic clock adjustments that are applied between the occurrence of the measurement event and the generation of the measurement output. In this manner, jitter is reduced and metrology performance is improved.