Hydrant Sensor Clock Offset Synchronization for Outage Monitoring

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Solution Overview

Problem

Water distribution systems face challenges in accurately monitoring and locating issues due to their large geographic size and complex propagation patterns, which makes it difficult to determine the cause of service disruptions, especially with wireless sensor communication introducing significant costs and complexity.

Innovation Solution

The implementation of a hydrant-based monitoring apparatus with a sensor, processor, local clock source, and communication interface that wakes from a low power mode to a sensing mode to collect data, associates it with a local clock time, and then transmits it to an external monitoring system with an offset for synchronization, allowing for precise timing and location analysis across the system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If wireless communication is used for sensor data transmission in remote monitoring devices, then the monitoring coverage and accessibility are improved, but the system cost and complexity increase significantly

Engineering Contradiction:

Improvemonitoring coverageVSAvoidsystem complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The system segments the monitoring function by deploying distributed sensor nodes at strategic locations (hydrants, valves, pumps) throughout the water distribution system. Each node independently performs sensing, local processing, and selective wireless communication, dividing the overall monitoring task into manageable units that reduce per-node complexity while maintaining system-wide coverage

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary actions by pre-positioning sensor nodes at critical infrastructure points and pre-configuring them with local processing capabilities and communication protocols. This allows the system to be ready for immediate monitoring without requiring complex real-time decision-making or high-bandwidth communication infrastructure

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If the system operates in low power mode to conserve energy, then energy consumption is reduced, but the frequency of data collection and transmission decreases

Engineering Contradiction:

Improveenergy consumptionVSAvoiddata collection frequency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The system dynamically adjusts its operational state based on conditions. Sensor nodes transition between low-power sleep mode and active sensing/transmission modes based on detected events, time of day, water flow conditions, and communication availability. This dynamic behavior allows the system to maximize energy efficiency during normal operation while maintaining adequate monitoring coverage when needed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements periodic wake-up cycles where sensor nodes alternate between extended low-power sleep periods and brief active periods for sensing, processing, and communication. During active periods, nodes collect data, synchronize clocks, and transmit information. This periodic operation pattern balances energy conservation with maintaining system monitoring capability

Inventive Principle:

Principle #19Periodic action

3Reliability

If local clock sources are used in distributed sensor nodes, then timing independence and operation during communication outages are improved, but clock synchronization accuracy across the system deteriorates

Engineering Contradiction:

Improveoperation during outagesVSAvoidtiming accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system implements feedback-based clock synchronization where sensor nodes periodically compare their local clock times with a reference clock (when communication is available) and adjust their local clocks accordingly. The system tracks and compensates for clock drift over time, using feedback from time synchronization messages to maintain accurate timing even as nodes operate independently between communication cycles

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system uses an intermediary approach by introducing a reference clock source that acts as a time master for the distributed network. When communication is available, nodes synchronize to this intermediary reference. When communication is unavailable, nodes rely on their local clocks but continue to operate with the previously synchronized time baseline, allowing independent operation while maintaining relative timing accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11792734B2Post-event modification of local clock values in water distribution system

Publication Date: 2023.10.17 MCWANE INC

AI summary

A hydrant apparatus may be employed to monitor a water distribution system, and may include a sensor, a processor, and a local clock source. The apparatus may wake from a low power mode to a sensing mode, receive the sensor data, associate the sensor data with a first local clock time, and return the apparatus to the low power mode from the sensing mode. The apparatus may subsequently wake to an operational mode, determine a second local clock time subsequent to the first local clock time, associate an external clock time with the second local clock time, determine an offset for the received sensor data based on the first local clock time and the association between the second local clock time and the external clock time, and transmit the sensor data and the offset to an external monitoring system.