Water Meter Wire Tamper Detection Using Diode Response
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Solution Overview
Problem
Existing water meter systems face challenges in accurately reporting water utilization due to potential tampering with the meters or their registers, which can lead to incorrect counting of water flow, and conventional tamper detection methods require a third wire that not all systems have.
Innovation Solution
A system and method that utilize a flow meter producing output pulses, a switching-element, a diode in parallel with the switching-element, and a processor to apply a forward voltage and detect responses, determining if there is a short, cut, or untampered wire condition by comparing the magnitude of the response to different electrical states, without needing a third wire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tamper detection methods using a third wire are employed, then wire tampering detection capability is improved, but device complexity and installation requirements worsen
Solution Approach 1:
The patent extracts the tamper detection functionality from the traditional three-wire configuration and implements it within the existing two-wire setup by utilizing the body diode of the switching element. This removes the need for an additional third wire while maintaining detection capability.
Solution Approach 2:
The body diode of the switching element serves multiple functions: it enables normal switching operation during water flow measurement and simultaneously provides tamper detection capability by monitoring current flow patterns. This multi-functionality eliminates the need for dedicated separate components.
2Device complexity
If existing two-wire systems are used without tamper detection, then device complexity is reduced, but reliability against tampering worsens
Solution Approach 1:
The switching element's body diode serves itself to provide tamper detection functionality without requiring external additional components. The existing circuit elements are made to perform both their primary function and security function, achieving self-service protection.
Solution Approach 2:
The system detects wire tampering by monitoring changes in electrical parameters (current flow patterns, resistance values) through the body diode. Different tamper conditions produce distinct parameter signatures that can be identified by the microcontroller.
3Measurement precision
If advanced tamper detection systems are implemented, then detection accuracy is improved, but ease of operation and installation worsens
Solution Approach 1:
The patent merges the tamper detection circuitry with the existing water flow measurement circuit by utilizing the body diode of the switching element. This integration allows accurate detection of multiple tamper conditions without requiring separate installation procedures or additional wiring.
Solution Approach 2:
The body diode acts as an intermediary element that enables the microcontroller to detect wire tampering conditions without direct physical contact or additional sensing components. The diode's electrical characteristics serve as the mediator for detecting various tamper states.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively monitors the integrity of the wires between a water register and an electronic counter, accurately determining if the wires are shorted, cut, or intact, thereby preventing tampering-related errors in water flow measurement.
Implementation Method 1
a diode in parallel with the switching-element... apply a forward voltage to the diode, detect a response at the diode during the application of the forward voltage to the diode
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A system (with corresponding a method and computer program product) for sensing wire tampering of a utility service. The system comprises a flow meter configured to produce output pulses indicative of a flow through the utility service, a switching-element receiving the pulses from the flow meter, a diode in parallel with the switching-element, and a processor for recording the flow, and having a first wire and a second wire electrically connected to the switching-element and the diode. The processor is configured to apply a forward voltage to the diode, detect a response at the diode during the application of the forward voltage to the diode, and based on a comparison of a magnitude of the response to at least two of three different electrical states, determine if the detected response is indicative of a) a short between the first wire and the second wire, b) a cut in either of the first wire and the second wire, or c) an untampered wire condition.