Sensor Time Synchronization via Master Device Intermediary
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Solution Overview
Problem
Conventional time synchronization methods in sensor networks are inadequate for terminals with low computation performance and clock accuracy, particularly when using monotonously increasing incremental counters, as they require high microcomputer or CPU performance for clock deviation correction and propagation delay calculation.
Innovation Solution
A sensing system with a sensor, a data collection terminal master device, and a data collection terminal slave device, where the sensor appends timestamps based on its clock unit, and the master device calculates synchronization deviation and propagation delay using dummy packets to correct timestamps, allowing accurate time synchronization even with low computation performance and clock accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional time synchronization methods (NTP, RBS, FTSP, TPSN) are used to achieve accurate time synchronization, then time synchronization accuracy is improved, but the required computation performance of microcomputer or CPU increases
Solution Approach 1:
The patent introduces a master device as an intermediary that performs complex time synchronization calculations on behalf of sensors. The master device receives timestamped data from sensors, calculates propagation delays and clock deviations using dummy packets, and corrects timestamps centrally. This mediator approach allows sensors to use simple incremental counters without high computation performance, while the master device handles the computationally intensive synchronization tasks.
Solution Approach 2:
Sensors append timestamps to their data using their own local clocks without requiring complex synchronization algorithms. Each sensor independently marks its data with local time information, and the system as a whole achieves synchronization through the master device's correction process rather than through complex inter-sensor negotiations.
2Measurement precision
If conventional time synchronization methods are used to correct clock deviation and propagation delay, then time synchronization accuracy is improved, but the configuration of terminal is restricted
Solution Approach 1:
The master device acts as an intermediary that accommodates various terminal configurations. It can work with sensors using different clock types (incremental counters, accurate clocks) and different communication patterns, centralizing the complexity of adapting to various configurations in the master device rather than requiring each sensor to support multiple synchronization protocols.
Solution Approach 2:
The synchronization system is designed to be universal, working with sensors that have different clock accuracies and computation capabilities. The master device implements a unified synchronization approach that can handle incremental counters, accurate clocks, and various communication patterns, making the system adaptable to diverse sensor configurations without requiring sensors to be highly capable.
3Loss of information
If sensors append timestamps using their own clock units, then time information is available for sensor data, but the required performance of sensor's microcomputer or CPU increases
Solution Approach 1:
Sensors independently append timestamps to their data using simple local incremental counters without requiring complex synchronization algorithms. This self-service approach allows sensors to mark their data with time information using minimal computation, and the system achieves overall synchronization through the master device's centralized correction process rather than through complex inter-sensor negotiations.
Solution Approach 2:
The master device serves as an intermediary that receives timestamped data from sensors using simple clocks and performs the computationally intensive tasks of calculating propagation delays and correcting timestamps. This allows sensors to use low-performance incremental counters while the master device handles the complex synchronization mathematics.
Data Source
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AI summary
Upon receiving a dummy packet, a data collection terminal slave device (2) appends, to a return packet, a timestamp indicating the reception time of the dummy packet and a timestamp indicating the transmission time of the return packet, and transmits the return packet to a data collection terminal master device (3). When performing a time synchronization process, the data collection terminal master device (3) transmits the dummy packet to the data collection terminal slave device (2). Upon receiving the return packet, the data collection terminal master device (3) calculates a synchronization deviation time of the data collection terminal master device (3) and the data collection terminal slave device (2) and a propagation delay time between the data collection terminal master device (3) and the data collection terminal slave device (2), based on the transmission time of the dummy packet and the reception time of the return packet, and the reception time of the dummy packet and the transmission time of the return packet obtained from the timestamps of the return packet.