Fluid Meter Clock Synchronization via Periodic Reset
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Solution Overview
Problem
Conventional fluid meters in remote reading networks face challenges with time discrepancies due to low-quality quartz clocks, leading to inaccurate time-stamping and increased network dimensioning and power consumption, especially in battery-operated devices, as they require frequent and costly precise clock updates.
Innovation Solution
A method where the meter module enters receiving mode periodically to receive reset messages from the server to correct clock discrepancies, allowing for immediate and periodic adjustments to maintain accurate time-stamping without significantly impacting network dimensioning or power consumption, using a reduced two-way communication mode to minimize infrastructure and energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequent clock updates are performed to maintain time accuracy, then time-stamping precision is improved, but network load and power consumption increase
Solution Approach 1:
The patent implements periodic clock updates rather than continuous updates. The meter module waits for predetermined time intervals (e.g., daily at specific times) to synchronize its clock with the server, reducing the frequency of communication while maintaining acceptable time accuracy for billing purposes.
Solution Approach 2:
The meter module autonomously manages its clock synchronization by automatically detecting when updates are needed and initiating communication with the server without external intervention. The system self-regulates the update timing based on its internal clock and predetermined schedules.
2Measurement precision
If more precise clocks are used in meters, then time accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent accepts the use of inexpensive quartz crystals with inherent precision of +/-20 ppm, recognizing that while they drift over time, the cost savings are significant. The system compensates for this drift through periodic synchronization with the server rather than requiring expensive atomic clocks.
Solution Approach 2:
The system uses feedback from the server to correct clock discrepancies. The server provides time information that the meter module uses to adjust its internal clock, creating a feedback loop that maintains accuracy without requiring expensive hardware.
3Reliability
If two-way communication mode is implemented for regular updates, then time synchronization reliability is improved, but device complexity and infrastructure requirements increase
Solution Approach 1:
The patent segments the communication function into distinct phases: the meter module transmits measurement data unidirectionally, and the server independently handles clock synchronization. This separation allows the meter to remain simple while achieving reliable synchronization through server-initiated updates.
Solution Approach 2:
The server acts as an intermediary that manages the complex synchronization logic. Rather than requiring complex two-way communication protocols between meters and the reading system, the server mediates by providing time information that simplifies the meter's communication requirements.
Data Source
AI summary
The invention relates to a method for remotely reading fluid meters, according to which a meter comprises a module having a metering clock and a wireless transmitter for transmitting a frame of time-stamped remote-reading information to a server which comprises a server clock; after every N frames are transmitted, the meter module enters a receiving mode (Rx) for a period of time (ΔRx); upon receiving a frame of time-stamped information, the server determines the difference between the time information contained in the received frame and the time information provided by the server clock; then, if the difference is greater than a predetermined limit (ΔL), the server sends a reset message to the meter; upon receiving the reset message, the module of the meter updates the meter clock.