Patent Description:
Domestic and business premises commonly rely on a source of water for various purposes. For water usage tracking purposes, such premises commonly have a water meter positioned to meter the amount of water flowing in a supply line to the premises.

In nearby fluid conduits, leaks can occur. Some such leaks can be minor and have minimal consequences, while other leaks can be significant and/or have significant consequences if they are not identified early and repaired.

Some prior techniques of fluid leakage detection in fluid conduits, such as water mains, have needed maintenance personnel to periodically attend the site of suspected leaks around a water supply network and be present at the site for significant periods while using cumbersome and/or costly listening devices. Such techniques may sometimes take years to effectively monitor and determine leaks with in a water supply network. The engagement of such leak detection services can represent a significant cost to water utilities.

<CIT> discloses a leakage determination system which includes a first detection means for detecting a prescribed physical quantity indicating a state of a fluid in piping, a second detection means for detecting vibration propagating through the piping, and a leakage determination means for performing leakage determination based on the physical quantity detected by the first detection means and the vibration detected by the second detection means.

<CIT> discloses a system for leak detection of a fluid in a pipe network, comprising flow meters, and vibration detectors adapted to be attached to a pipe at a location in the pipe network, wherein a processor analyzes signals generated by the flow meters and vibration detectors to identify the presence of one or more leaks in the pipe network.

It is desired to address or ameliorate one or more shortcomings or disadvantages of prior vibration sensors, leak detection devices or leak detection techniques, or to at least provide a useful alternative thereto.

The present invention provides a water meter system, a fluid supply system, and a method of leakage detection in a fluid supply network, according to the appended claims.

Some embodiments generally relate to fluid meters, such as water meters, and to systems and methods employing such fluid meters. Some embodiments generally relate to vibration sensors. Particular embodiments relate to vibration sensors for fluid leak detection, optionally in combination with a water meter, and to systems and methods employing such vibration sensors.

Referring in particular to <FIG>, a fluid metering system <NUM> is described in greater detail. The system <NUM> comprises at least one water meter <NUM> that is in communication with a server <NUM> via a network, such as a public or partly public network including wireless telecommunications infrastructure. The server <NUM> has access to a data store <NUM>. In practice, many fluid meters <NUM> will form part of system <NUM>, with each of those meters <NUM> being in communication with the server <NUM> via network <NUM>.

A housing <NUM> (<FIG>) houses a water meter <NUM> and a sensor installation <NUM> comprising a flow sensor <NUM> for sensing fluid flow <NUM> within the conduit, and one or more sensors <NUM>, <NUM> for sensing at least one condition of the fluid or fluid conduit.

In some embodiments, the water meter <NUM> is a static flow meter such as an ultrasonic or magnetic flow meter. Other embodiments may comprise a mechanical flow meter. This meter will be configured to measure fluid flow characteristics such as maximum/minimum flow rate, reverse flow, and other characteristics within a fluid conduit, referred to for convenience as lumen <NUM>. The meter may comprise a flow tube <NUM> having a hollow internal space to receive and conduct fluid flow <NUM> from fluid supply side <NUM> and suitable for sensing a fluid condition about a fluid flow <NUM>, using flow sensor <NUM>, and embedded flow sensors <NUM>, <NUM>. The flow tube <NUM> may be made of a suitable material to allow for fluid sensing by the flow sensor <NUM>. Some embodiments may comprise a brass flow tube.

Flow sensor <NUM> is communicatively and electrically coupled to first controller <NUM>, having a processor <NUM> and memory <NUM>. The first controller <NUM> receives power from power supply <NUM> and transmits power through to the other system components. First controller <NUM> is communicatively and electrically coupled to a second controller <NUM>, which itself is electrically and communicatively coupled to one or more sensors <NUM>, <NUM>. In some embodiments of the invention, the functions of the first controller <NUM> and second controller <NUM> may be consolidated into a single controller or processor. In some embodiments, one or more functions of the first controller <NUM> and second controller <NUM> may be conducted by another number of controllers and/or processors. For example, embodiments may include additional processor circuitry, such as a digital signal processor (DSP), but such additional processor circuitry should be understood to be included as part of the controller or processor described herein unless context indicates otherwise.

The first controller <NUM> only turns on power to the second controller and the one or more sensors when it is desired to take a sensor reading in relation to fluid conditions in the conduit, and the first controller removes power from the one or more sensors at other times. The desired sensing interval may coincide with a daily data payload, and be conducted according to a configurable interval.

The one or more sensors <NUM>, <NUM> are electrically and communicatively coupled to a second controller <NUM>, having a processor <NUM> and memory <NUM>, configured to control activation of the one or more sensors according to a configurable interval. The one or more sensors may include sensors to detect fluid pressure, vibrations within the lumen <NUM>, temperature, and other fluid characteristics. Sensors to detect other conditions may also be provided, and more than one type of sensor may be used to measure one type of condition. Depending on what information is desired to be gathered, a sub-set of those sensors may be comprised in system <NUM>. For example, it may be desired in some instances to measure fluid flow rate, fluid pressure, and conduit vibration for leak detection, and in other instances to measure fluid flow rate, conduit vibration for leak detection, and water quality.

Commercially available sensors may be used as sensors under the control of the second controller, modified as necessary to operate at low power, or modified to allow for small measurement thresholds. The separation of second controller <NUM> and sensors <NUM>, <NUM> from the first controller <NUM> and flow sensor <NUM> may allow for adaptation of existing, commercially available flow meters to be used as water meter <NUM>, with additional modification through inclusion of a second controller <NUM> within the housing <NUM>.

In some embodiments, first controller <NUM> and second controller <NUM> may comprise a single main controller, having at least one processor and memory, and performing the same functions.

A power supply <NUM> provides power to the housed system, including the one or more sensors, through connection to the meter's first controller <NUM>, which in turn supplies power to the second controller <NUM>.

A communications module <NUM> is electrically and communicatively connected to the first controller <NUM>, for the purpose of communicating with and receiving instructions from a client device <NUM> over a network <NUM>,.

Referring particularly to <FIG>, the housing <NUM> may be an IP68 (acc. EN60529) rated enclosure that is manufactured from plastic that is highly resistant to UV damage, temperature fluctuations, and other environmental factors. In some embodiments the meter system <NUM> within housing <NUM> may be sufficiently watertight to withstand full immersion in water for at least <NUM> hours without sustaining permanent damage. The threaded or flanged coupling portions <NUM> of the meter may be brass, and provide an upstream and/or downstream orientation with an upstream end coupled to the supply network and a downstream end coupled to the customer premises. In some embodiments, a suitable alternative metal or material may be substituted. Some embodiments comprise a completely metallic flow tube <NUM>. The threaded coupling portions <NUM> may be joined by a conductive metal band. In embodiments comprising a plastic flow tube or other material, safety or bonding wires may be used in order to allow meters to be safely installed or maintained without risk of electrocution. The meter system <NUM> within housing <NUM> should meet minimum electro-magnetic immunity and electro-static discharge (ESD) standards such as IEC <NUM>-<NUM>.

The meter system <NUM> may have environmental limits of at least -<NUM> to +<NUM> degrees Celsius, and <NUM>% to <NUM>% humidity while operating or in storage. The meter system <NUM> may be capable of operating in direct sunlight at up to at least <NUM> degrees Celsius (in some embodiments up to <NUM> degrees Celsius) ambient air temperature.

The meter system <NUM> may provide suitable electrical conductivity across the housing and connectors to ensure continuity of earth for installations which rely on water pipes as a means of earthing the mains electricity supply.

In some embodiments, the meter system <NUM> construction materials will be chosen to minimise the recycling value of the meter, using a minimum of materials with high recycling value such as copper or brass to reduce risk of theft or vandalism of the meter system <NUM>.

The housing <NUM> may also accommodate buttons, switches, lights, or manually actuated systems which would allow for an operator to ascertain an operational status of the meters, or manipulate certain functions of the meter, such as manual power operation, taking of readings, and forcing a data payload. These functions may be accommodated in external display <NUM> or external interface <NUM>. For example, an activation mechanism that wakes the meter from its sleep/dead/low-power mode so that it turns on and connects to the network. An embodiment of this mechanism may be a push button, magnet, or an LED actuation featured on external interface <NUM>.

The housing <NUM> may further allow for a local display <NUM> readable in direct sunlight from a suitable distance, nominally <NUM>. The local display <NUM> may be capable of displaying information about the meter or sensed conditions in the lumen <NUM>, such as total water consumption in kL with a resolution of <NUM> or better, the current time of day, the meter state or triggered alarms, instantaneous flow rate, communication status, the last readings for pressure, water temperature, or other information.

Housing <NUM> may provide for access to external display <NUM>, showing local visible indications (for example using visible LEDs) of:.

In some embodiments, the installation <NUM> and housing <NUM> may be oriented horizontally or vertically, and may be installed directly in line with a lumen <NUM> or be installed in a bypass tube connected to a lumen <NUM>. The installation may be installed with minimum upstream distance, on a lumen <NUM> connected to a fluid supply network <NUM>. The meter system <NUM> may continue to meet all requirements in any installed orientation.

In some embodiments, a high-gain antenna may be installed in electrical and communicative connection with communications module <NUM>, to improve signal strength in areas of low coverage. An embodiment may encompass a low profile fixture, situated on the lid of the meter or within the meter housing <NUM>. Alternative embodiments may encompass at least one external antenna port suitable to receive a later installation of a high-gain antenna, the antenna port being in electrical and communicative connection with the communications module. In such embodiments the antenna and antenna port may comprise a suitable material, meeting an IP68 rating, and be resistant to UV damage, temperature fluctuations, and other environmental factors. In other embodiments any required communications antenna would be mounted internally.

The power supply <NUM> to the meter <NUM> supplies power to all components. The power supply <NUM> may be of a kind having a long life and low self-discharge, suitable to be installed for long periods (ideally <NUM>, <NUM>, or more years) without requiring a replacement. An embodiment of the power supply <NUM> may be in the form of a lithium battery, with capacity to <NUM>. 0V (@<NUM>. 5a @<NUM>% duty cycle) of <NUM> Ah, nominal voltage of <NUM>. 6V, maximum <NUM> second pulse to <NUM>. 0V of 3A, maximum pulse length @<NUM>. 5A to <NUM>. 8V of <NUM> seconds, no delay time to <NUM>. 5A, a weight of approximately <NUM>, a safe operating range of -<NUM> to +<NUM>, and a <NUM>% capacity retention after <NUM> years, for example. However, other suitable power supplies may be used with different operational and/or functional parameters to those listed immediately above. The housing <NUM> should allow access to the power supply <NUM> for maintenance or replacement.

Referring to <FIG>, the system <NUM> features both a first <NUM> and second controller <NUM>.

The first controller comprises a processor <NUM> and a memory <NUM>. The memory <NUM> may comprise a combination of volatile and non-volatile computer readable storage and has sufficient capacity to store program code executable by processor <NUM> in order to perform appropriate processing functions as described herein. For example, processor <NUM> executes program code stored in memory <NUM> to activate the second controller <NUM> or flow sensor <NUM>, which in turn take readings as required. Processor <NUM> may activate other system components within water meter <NUM>, such as external display <NUM>, external interface <NUM>, and the communications module <NUM>.

The first controller <NUM> also receives power through power supply <NUM>, and provides the power from power supply <NUM> through wired connections to the second controller <NUM> and sensors <NUM>, <NUM>, as well as to the remainder of the system components.

The first controller <NUM> interfaces with communications module <NUM>, and is capable of receiving instructions or firmware upgrades over a network <NUM>, and sending stored data through network <NUM>. This data may relate to meter status, or sensed conditions within the lumen <NUM>.

The second controller <NUM> comprises a processor <NUM> and a memory <NUM>. The memory <NUM> may comprise a combination of volatile and non-volatile computer readable storage and has sufficient capacity to store program code executable by processor <NUM> in order to perform appropriate processing functions as described herein. For example, processor <NUM> executes program code stored in memory <NUM> to provide power to sensors <NUM>, <NUM> and to take and store data sensed from sensors <NUM>, <NUM> about a fluid condition within a lumen <NUM> of a flow tube <NUM>. The flow tube <NUM> may form part of a meter assembly comprising meter <NUM> and the metering functions of the meter <NUM> are carried out in relation to fluid flowing in the flow tube <NUM>.

Memory <NUM> may store sensed fluid data in a data register, to be sent through communications network <NUM> upon request of a client device <NUM> connected to network <NUM>, or as instructed by program code stored in memory <NUM>, <NUM>.

Processors <NUM>,<NUM> are referred to in <FIG> as CPUs (central processing units). This term is used in a non-limiting capacity and any suitable processor or microprocessor may be used. In embodiments where the first controller <NUM> and second controller <NUM> comprise a single controller, the single controller may have at least one memory and at least one processor according to the above.

The first controller <NUM> or second controller <NUM> may be optionally configured to receive instructions and communicate directly with a client device <NUM>, for example a handheld device or laptop computer, in order to locally configure or diagnose the meter through a local data interface <NUM>. Embodiments of local interface <NUM> may be in the form of an optical, wired, or wireless communication system, suitable for connection to a laptop computer and/or handheld device. It is envisioned that this local data interface <NUM> may only be accessed in cases of meter fault or if other changes are required in the field, as configuration of the meter is otherwise possible over a network <NUM> through communications module <NUM>.

Through this local data interface <NUM>, all parameters such as alarms, transmission intervals, and other related fields are may be configurable or programmable. Diagnostic logs providing meter information may be extracted through this interface. It is desirable that connection to the local data interface <NUM> uses zero or minimal power from the power supply <NUM>, instead being powered by the client device itself.

In some embodiments, first or second controller memory <NUM>, <NUM> may store a predetermined data storage capacity for storage of a minimum amount of measurement data. For example, first or second controller memory <NUM>, <NUM> may have sufficient storage capacity to store a minimum of <NUM>, <NUM>, <NUM> or <NUM> days of time-stamped fluid data, together with the corresponding interval data, meter firmware information, and other pertinent information.

Further requirements for the local data interface <NUM> of some embodiments include the local data interface <NUM> providing a capability to retrieve all stored billing data, events, and alarms. The local data interface <NUM> may also be required to provide a capability to update firmware and to read or update configuration.

Access to the local data interface <NUM> may be secured through a standards based mutual authentication scheme. Any keys or certificates used may be able to be revoked and/or replaced. In some embodiments, the local data interface supports rolebased access control. At a minimum "read-only", "configure", and "full access" roles may be supported. All of the access to the local data interface may be logged for audit purposes. At a minimum the audit log may include date/time, actions, and identity of user.

The first controller <NUM> or second controller <NUM> may have an internal clock. Sensed fluid flow characteristics may be time-stamped where required by a time set on the internal clock.

Referring now to <FIG>, the water metering system <NUM> further comprises one or more servers or server systems, referred to herein for convenience as server <NUM>, in connection with at least one wired client device <NUM> and a data store <NUM>. In some embodiments, client device <NUM> comprises a wired computing device, or portable computing device such as a laptop or smartphone. Server <NUM> may comprise, or be arranged as, a supervisory control and data acquisition (SCADA) server to receive data from water meters <NUM> at various different locations.

This data is received over a data network comprising suitable communications infrastructure that is at least partially wireless, such as a cellular network.

For example, the communications modules <NUM> of flow meter systems <NUM> may be configured to transmit data to server <NUM> using the GSM or GPRS/<NUM> standards for mobile telephony or their technological successors.

Thus, communication module <NUM> in communication with server <NUM> by direct mobile data communication using available mobile telephony infrastructure, rather than using a series of hops and other infrastructure to transmit messages. Alternatively, lower power, shorter distance wireless communication techniques may be employed, for example where a local wireless data hub is in sufficient proximity to support wireless communication with the communications module <NUM> within a nearby water meter system <NUM>. However more direct forms of communication from the communication module <NUM> to the server <NUM> are preferred for simplicity, speed, and reliability.

Server <NUM> processes the data received from the communications module <NUM>, and stores it in data store <NUM> for subsequent retrieval as needed. Data store <NUM> may comprise any suitable data store, such as a local, external, distributed, or discrete database. If the data received at server <NUM> from meters <NUM> indicate an alarm condition in any one or more of the meters <NUM>, server <NUM> accesses data store <NUM> to determine a pre-determined appropriate action to be taken in relation to the specific alarm condition and then takes the appropriate action. The action to be taken may vary, depending on the meter <NUM>, for example where some meters <NUM> may be configured to sense different conditions over others. Such actions may include, for example, sending one or more notifications, for example in the form of text messages and/or emails, to one or more client devices <NUM>.

Regardless of whether an alarm condition is indicated by the data received at server <NUM> from meters <NUM>, the received data is processed and stored in data store <NUM> for later retrieval by a server process and/or at request from a client device <NUM>. For example, server <NUM> may execute processes (based on program code stored in data store <NUM> for example), to perform trending and reporting functions to one or more client devices <NUM>.

The communications module <NUM> may be enabled for bidirectional communication with server <NUM>, so that firmware updates can be received and/or diagnostic testing can be performed remotely, and that client devices may remotely configure data payload intervals, and/or request current (or real-time) data from the meter.

Referring to <FIG>, communications module <NUM> is described in further detail. The communications module may be electrically and communicatively connected to a first controller <NUM>, receiving power from power supply <NUM> through this connection, or directly in some embodiments.

The configuration of communications module <NUM> may include an antenna, and subscriber identity module (SIM) card. The communications module <NUM> may comprise additional components and/or circuitry (not shown) as judged by a person of ordinary skill in the art to be necessary or desirable in order to carry out the functions as described herein.

Some embodiments of the meter <NUM> have communication requirements including the meter <NUM> being capable of measuring and reporting over a network <NUM> on request:.

In some embodiments, the meter <NUM> requires being capable of supplying identification data to the communications network on request.

The meter <NUM> may require being capable of supplying all stored interval data, register snapshots, events, alarms and any other business data or status information to the communications network on request and/or as scheduled.

In some embodiments, the meter <NUM> requires being capable of accepting firmware upgrades over the communications network. All firmware components may be upgradeable. The firmware upgrade process may be tolerant of communications outages, power interruptions, head end system outages, and errors in transmission.

Meter systems <NUM> may require being capable of independently and automatically detecting failures, and recovering or rolling back to previous known good settings or parameters (images) when recovery is not possible. The meter <NUM> may be capable of accepting configuration changes and reporting current configuration over the communications network <NUM>.

In some embodiments, the meter <NUM> requires being capable of having its time synchronised over the communications network <NUM>.

The meter <NUM> is required to have a configurable communications retry and back-off sequence that allows for resending of data payloads that were unsuccessfully sent to server <NUM>. For example, if the meter attempts to send its data payload and is unsuccessful, it may retry a configurable number of times, such as <NUM>, <NUM>, <NUM>, or some other amount of times. After this, it may return to deep sleep/low-power mode and attempt communications a number of hours later.

In other embodiments, the meter may retry sending unsuccessful payloads, and then return to deep sleep/low-power mode until the next scheduled transit time (for example, the following day). In such an embodiment, the meter and communications module may require the ability to handle larger than normal data payloads. For example, if the meter has not been able to communicate for <NUM> days, this would result in a payload <NUM> times the size of a regular payload that would cause the communications module <NUM> to be activated for a prolonged period.

In some embodiments, sensors <NUM>, <NUM> are physically and/or electrically connected to second controller <NUM> and sense fluid conditions within the lumen <NUM>. In other embodiments, the sensors <NUM>, <NUM> may be electrically and/or physically connected to the first controller <NUM> or, where the functions of the first and second controller are provided by one controller, the sensors <NUM>, <NUM> may be so connected to that controller. These sensors <NUM>, <NUM> may comprise more than two sensors or sensor functions, at least one sensor including a vibration sensor, a pressure sensor, and stray current sensor. Sensors <NUM>, <NUM> may include other sensors or sensor functions to sense electrical conductivity, fluid temperature, pH level and free chlorine levels. In some embodiments, multiple fluid conditions may be sensed by individual sensors.

<FIG> shows an embodiment where the meter system <NUM> is installed in-line with a fluid supply conduit <NUM>, to communicate fluid from the supply conduit <NUM> through a fluid flow tube <NUM> via which conditions of fluid flow in the lumen <NUM> are detected. In this embodiment, a vibration sensor <NUM>, a sensor installation <NUM> and other sensors <NUM>, <NUM> are positioned on/in or in relation to the flow tube <NUM>.

Sensors <NUM>, <NUM> may be installed separately, or as one unit, depending on the configuration of sensors used. Sensor <NUM>, <NUM> sense at least one condition within the lumen <NUM>. Described sensors may be ultra-low powered, with low start-up currents and small stabilization times in order to minimize power consumption.

In some embodiments, sensor <NUM> comprises a vibration sensor <NUM>, interfaced with the lumen <NUM> in order to detect vibrations in the upstream fluid supply conduit system. In some embodiments, a part of the vibration sensor <NUM> is in direct contact, for example by abutment, with a portion of the meter flow conduit coupling <NUM>, positioned on the (upstream) supply side <NUM>. The sensor <NUM> can be physically interfaced with the conduit coupling <NUM> using a suitable fixture technique. For example, an adhesive fixture or mechanical method of fixture such as a gasket fixture or screws can be used, provided that the fixture would not otherwise provide mechanical action in the form of further vibration.

<FIG> depicts an embodiment of the vibration sensor <NUM>, comprising a piezoelectric sensor system. The sensor <NUM> comprises at least one thin stacked electrically conductive plate <NUM> (made from a suitable material such as copper) and two or more piezoelectric elements or plates <NUM>. The stack of piezoelectric plates <NUM> and conductive plates <NUM> are disposed between a seismic mass <NUM> and a base unit <NUM>, which are connected to each other. Affixing shaft <NUM> clamps or connects the seismic mass <NUM> to or onto base unit <NUM>, which may exert a compression force in rest state, but still allowing for small movement and compression of piezoelectric sensor plates <NUM> between copper plates <NUM>. The base unit <NUM> comprises one or more masses configured to convey vibrational movement from the material of the flow conduit to the piezoelectric plates <NUM>. The base unit <NUM> can also be an integral part of the meter flow conduit coupling <NUM> or flow tube <NUM> in the form of a cast mounting plate with provisions for fastening. The number of copper plate and piezoelectric layers may vary between embodiments. The example shown in <FIG> shows two copper plates <NUM> and three piezoelectric elements <NUM>. Conductive plates <NUM> may be substantially thinner than piezoelectric plates <NUM>, for example by a factor of around <NUM> to <NUM>. In some embodiments, the copper plate may be between <NUM>-<NUM> in thickness, whereas the piezoelectric plates may be <NUM>-<NUM> in thickness, for example. It should be understood that <FIG> does not portray a scale embodiment of vibration sensor <NUM>.

Vibrations transmitted along fluid conduits of an upstream fluid supply network may couple into the material of the flow tube of the meter <NUM> and thereby be transmitted to the base unit <NUM> that is connected to flow tube <NUM>, or in some embodiments the meter coupling portions <NUM>. When vibrations travel through base unit <NUM>, piezoelectric plates <NUM> are compressed between against seismic mass <NUM> and base unit <NUM>. One or more electrical conductors <NUM> may be connected to the copper plates <NUM> to carry current (or convey voltage differences) generated by the piezoelectric plates <NUM> to processing circuitry in the meter <NUM>. In some embodiments a plurality of piezoelectric plates <NUM> are used to provide an amplifying effect on the vibration signal.

Sensor <NUM> may be configured to provide sensed fluid condition data along conductors <NUM> to a second processor <NUM>, through process <NUM> or <NUM>.

The material of the flow tube <NUM> that the sensor <NUM> is affixed to should be constructed from a material suitable to conduct detectable vibrations along its surface. It is envisioned that upstream supply conduits and/or the flow tube <NUM> may be formed of or comprise vibration-conducting metals, such as brass, or copper, however in some embodiments may comprise suitable alternative vibration-conducting materials.

An embodiment of a leak detection method <NUM> using vibration sensor <NUM> is described in <FIG>. At <NUM> the vibration sensor <NUM> awaits activation from a second controller. Once a predetermined measurement interval (stored in memory <NUM>) has expired, the first controller <NUM> causes power supply <NUM> to provide power to the second controller <NUM> to listen to output signals from vibration sensor <NUM>. At stage <NUM>, the controller may await diagnostic information from vibration sensor <NUM>, and may await confirmation that sensor <NUM> is operational.

At <NUM>, vibration sensor <NUM> captures vibration data in the form of an analogue signal. A number of readings may be taken in order at stage <NUM>. The sensed data will be transmitted to the second controller <NUM> along conductors <NUM> and in some embodiments, stored in memory <NUM>.

At <NUM> a first or second controller <NUM>, <NUM> performs a Fast Fourier Transform (FFT) to the analogue time domain data. At <NUM> the FFT data may be subject to filtering, such as band pass filtering, to identify frequency ranges consistent with one or more predetermined leak conditions. An example of such an embodiment is rendered in <FIG> as a putative plot of the FFT output, with amplitude on the Y-axis and frequency on the x-axis.

At <NUM>, after any filtering is applied to the FFT data, the data may be subject to a comparison against predetermined thresholds, further indicating leak conditions. In some embodiments, the threshold <NUM> may comprise an integral threshold, where leak conditions may be assessed based on the integral of the range of frequencies within a band pass filtered range. In such embodiments, the total area in a frequency range may be the condition assessed by threshold <NUM>. <FIG> indicates one such example where the integral of a filtered frequency range <NUM> does not meet threshold <NUM>, despite the presence of frequencies in a predetermined range <NUM>. In such an embodiment, the integral <NUM> of frequency range <NUM> does surpass threshold <NUM> and as such, would be detected as a type of leak or leaks.

In some embodiments, threshold <NUM> may be an amplitude threshold, where both <NUM> and <NUM> contain frequencies <NUM>, <NUM> within the filtered range that exceed the amplitude threshold <NUM>. In such an embodiment, frequency range <NUM> would not surpass threshold <NUM> as although frequencies <NUM> within the filtered range are detected, their amplitude does not exceed the threshold.

In some embodiments, threshold <NUM> may be configured with a suitably low value, such that presence of a frequency with an amplitude greater than zero in a filtered range may indicate a type of leak or leaks. In such embodiments, frequency ranges <NUM>, <NUM>, <NUM> may all indicate the presence of a type of leak or leaks.

Various vibration frequency characteristics may be used to determine and differentiate different types or combinations of leaks. In some embodiments, at least one additional sensed characteristic of the fluid flow <NUM> may be used to identify at least one leak condition in conjunction with vibration data. For example, detection of a frequency in ranges <NUM>, <NUM>, <NUM> may not trigger an alarm condition unless it is detected in conjunction with a predetermined condition sensed by sensors <NUM>, <NUM> or by flow sensor <NUM>, for example, a detection of low flow rate, and/or detection of a low pressure. Where this additional condition is met, a frequency in the range of any of ranges <NUM>, <NUM>, <NUM> may indicate presence of a leak. Threshold <NUM> may be configured as per any of the above described embodiments, but also conditional upon the detection of at least one sensed fluid condition. In such embodiments, at least one sensed condition may be used in conjunction with the vibration such as temperature, pressure, flow rate, electrical conductivity, pH level, free chlorine levels, or other conditions sensed by sensors <NUM>,<NUM> or flow sensor <NUM>.

After this stage is completed in <NUM>, the first or second controller <NUM>, <NUM> updates an alarm condition in <NUM> indicating the presence of a leak or leaks, or indicating that no leak or leaks are detected. This alarm may be a binary flag, comprising at least one bit. In such embodiments, a flagged bit may indicate presence of any leak.

In some embodiments, at least one bit may be used to flag the presence of a particular type of leak, for example a connection leak, or the presence of multiple leak conditions.

At stage <NUM>, the alarm condition is stored within a first or second controller memory <NUM>, <NUM> to be sent with normal data payloads.

In some embodiments, sensor <NUM> or <NUM> comprises a gauge pressure sensor that may operate in the <NUM>-<NUM> bar (<NUM>-150mH<NUM><NUM>, i.e. in 'meters head of water') range. The data from the pressure sensor may be adjusted to accommodate the elevation of the meter and configuration of the meter <NUM> installation.

Some embodiments may comprise a commercially available pressure sensor having on-board analogue to digital conversion and incorporated temperature sensing capabilities. Such sensors should be reliable within the specified pressure range, and be ultra-low powered.

In some embodiments, the pressure sensor or other sensors <NUM>, <NUM> may be installed within the internal cavity (lumen <NUM>) of the flow tube <NUM>, in a sensor installation <NUM> having a housing that may be in direct contact with fluid flow <NUM>. In such an embodiment, the pressure sensor, sensor installation <NUM> and connections may be suitably waterproofed and resistant to wear from conditions of fluid flow <NUM>. In other embodiments, sensor installation <NUM> comprises sensors <NUM>, <NUM> in direct contact with fluid flow <NUM>. In other embodiments, sensor installation <NUM> may be installed on the external body of flow tube <NUM>. In such embodiments, sensors <NUM>, <NUM> may not require direct contact with fluid flow <NUM> in order to take readings.

In some embodiments, sensor <NUM>, <NUM> comprises a stray current detection sensor, optionally a magnetometer. The magnetometer may be located proximally close to the lumen <NUM> and configured to detect a magnetic field due to an electric leakage current present in or near the lumen <NUM>.

Embodiments allow for detection of a magnetic field due to a leakage current above a certain Ampere level that can be harmful to humans or other animals, for example such as a current of 1A. Alternative embodiments may allow for lower, or different current detection thresholds.

The stray current detection sensor may be configured to receive instructions from the at least one controller <NUM>, <NUM>. In some embodiments a second controller <NUM> may periodically poll the sensor to retrieve readings to be included in daily data payloads. Optionally to be polled at different times to the vibration sensor.

Detection of a stray current during a polling period may trigger an alarm condition, to be stored in a memory <NUM>, <NUM> and sent in a regular (e.g. daily) data payload to external server <NUM> in accordance with process <NUM>.

In some embodiments, the flow sensor/water meter system <NUM>, herein referred to as water meter <NUM> for convenience comprises a magnetic flow meter or an ultrasonic flow sensor <NUM> in electrical and communicative connection with a second controller <NUM>.

The flow meter controller <NUM> may be suitable for retaining measured flow data in memory <NUM> to be transferred with daily payload data over a network <NUM>. Commercially available flow meter systems may be used, modified in some embodiments to suitably interface with a second controller <NUM> and sensors <NUM>, <NUM>.

The water meter <NUM> may comprise at least a means for detecting and/or measuring fluid flow <NUM> within a lumen <NUM>, a means for detecting and/or measuring a minimum or maximum flow rate in a time period, means for detecting and/or measuring reverse fluid flow (that is, flow towards the fluid supply network <NUM>). Temperature, electrical conductivity, free chlorine levels, or other fluid flow characteristics may be sensed, measured, and stored by a first controller <NUM> or second controller <NUM> depending on the flow meter capabilities.

Some embodiments of the water meter <NUM> have further requirements, such as having a minimum flow rate, being in the range of <NUM>, <NUM>, <NUM> litres per hour or higher as necessitated by the meter size. The meter sizes may vary, and may be in the range of <NUM>, <NUM>, <NUM>, or <NUM>. Embodiments may comprise higher or lower sizes.

The meter <NUM> may require being configured with a maximum or minimum permissible error of measurement (MPE). In some embodiments this may comprise a range of <NUM>-<NUM>%. The configuration of the MPE may be consistent with NMI R49 and class II meters.

The meter <NUM> may require being capable of detecting and measuring reverse flow.

In some embodiments, the meter <NUM> requires being fitted with either a single check valve, or a dual check valve.

The meter <NUM> may require being capable of recording (with timestamp) peak daily instantaneous flow in litres per second with a resolution of about <NUM> litres. The meter <NUM> may require being capable of measuring and recording water pressure in m. H<NUM><NUM> (i.e. "Meters head of water"). This pressure value may be gauge pressure.

In some embodiments, the meter <NUM> requires being able to measure and store water consumption interval reads (the interval data), total water consumption accumulation (the accumulation register), and time aligned snapshots of the accumulation register (the register snapshots) (collectively known as billing data). The interval length for interval data may be configurable supporting at minimum the following values: <NUM> minute, <NUM> minutes, <NUM> minutes, <NUM> minutes, and <NUM> minutes. In some embodiments, other values may be used. An accumulation register may be measured and stored in kilolitres with resolution and significant digits based on meter size, with resolutions potentially in the range of about <NUM>,<NUM> to about <NUM>,<NUM>,<NUM> kL.

The interval data may be measured and stored in litres with resolution and significant digits based on meter size, with resolutions potentially ranging between <NUM> to <NUM>,<NUM>.

It is envisioned that data payloads may be transmitted from a first controller <NUM> across a network <NUM> once per predetermined time period (i.e. a day). This transmission frequency may be a configurable parameter, allowing for more or less frequent payload transmission. Data collection intervals for all sensed data may be configurable.

An embodiment of the data payload content is described below. The contents of the data payload may vary depending on the capabilities of the sensors used.

Volumetric fluid flow within the lumen <NUM> may be recorded and time-stamped every <NUM> minutes. In some embodiments, a shorter interval (such as <NUM> seconds) may be recorded and time-stamped for a first or second controller <NUM>, <NUM> to summarize through algorithms, and to be transmitted with a daily payload.

As some embodiments of the flow meter may record data every few seconds, only the value and timestamp of the maximum flow rate each day may be transmitted. This data is valuable to determine instantaneous flow spikes at each meter <NUM>.

In some embodiments of the meter <NUM>, temperature and/or electrical conductivity may be sensed. These may be sensed either with embodiments of sensors <NUM>, <NUM> or the flow sensor <NUM>. In embodiments where these conditions are sensed, time stamped values of the sensed fluid data may be recorded at configurable intervals, for example, every <NUM> hours. This dataset is to be transmitted daily along with the main flow data payload.

In monitoring power consumption, voltage level of the power supply <NUM> may be transmitted along with daily payloads to monitor life. Additionally, daily meter communication activity time may be recorded and transmitted with the daily payload as an indicator of meter power consumption based on its attempts (successful or unsuccessful) to connect to the network <NUM>. Daily activity time may indicate the time in seconds that the meter was activating the communications module <NUM>.

In some embodiments, alarms to come with a daily payload may be customer leakage alarms, potentially a binary flag indicating continual usage (for example, a recorded flow rate of greater than <NUM>/h for <NUM> hours. This value may be configurable, and have a default value prescribed.

A reverse flow alarm may be recorded in a binary flag. Reverse flow volume may be recorded in litres of fluid flowing in the reverse direction, for example, toward the water supply network.

An empty pipe alarm may be indicated through a binary flag, and detectable through operation of the flow sensor <NUM>.

A Tamper alarm will indicate presence of strong magnetic fields or other electrical sources that effect a magnetic flow meter embodiment. This may optionally indicate tampering through vandalism or opening the water meter housing <NUM>.

Some embodiments of the flow sensor <NUM> configuration would allow for a high/low pressure alarm. The threshold for this alarm may be configurable per meter, having an initial default value. This alarm may be able to be enabled or disabled by user choice.

High/low temperature alarms may be user configurable, having default high and low temperature threshold values stored in the first or second controller memory.

A high flow alarm may indicate whether fluid flow <NUM> within the lumen <NUM> is abnormally high for a defined period of time. This alarm may be triggered based on a default alarm threshold triggering value and may be configurable. Triggering of this alarm may indicate the presence of a broken pipe, for example.

A network leak alarm may be a binary flag and may be based on frequency output of the vibration sensor. When an identified frequency is detected that has amplitude over a defined threshold, and that is characteristic of a fluid supply network leak, this alarm will be triggered.

These alarms may require acknowledgement from server <NUM>, and may transmit again upon change of state. If not acknowledged by server <NUM>, after a suitable interval, the meter <NUM> may continue to report the alarm binary value in the data payload until acknowledgement from the server <NUM> is received.

Through the server <NUM>, multicast end-point firmware in the form of binary files, and configuration data may be able to be sent to some or all of the end-points meters <NUM>. The mechanism for this may be efficient such that it has minimum impact on battery life. The at least one controller <NUM>, <NUM> may store sent firmware/configuration binary files, and only apply them once fully downloaded and certified. If the data received by the meter <NUM> is incomplete or corrupted, some embodiments of the at least one controller <NUM>, <NUM> may instead rely on existing configurations until such time as the new configuration data is acquired, rather than overwriting existing files.

A typical daily data payload is estimated to be approximately <NUM> bytes, including all mandatory and optional parameter data sets listed in the below table. In some embodiments, the payload will use the constrained application protocol (CoAP) and JavaScript Object Notation (JSON) or binary messages. An embodiment of a data payload, provided by way of example only, may comprise the following fields and data size distribution:.

Other data may be transmitted with daily payloads depending on meter and sensor configuration.

Through access to the local data interface <NUM>, a user may directly access or trigger the sending of payload data, or locally request measurements from the meter <NUM>.

Payload data requirements according to some embodiments include the meter <NUM> being capable of locally storing (including in the absence of functioning communications) at least:.

In some embodiments, the meter <NUM> also requires being capable of locally storing information recorded as an event which may be user configurable. The meter <NUM> may require being capable of recording as an event or alarm on a configurable basis:.

In some embodiments, the meter <NUM> may require being capable of recording as an event or alarm on a configurable basis the following features (where a suitable sensor is fitted):.

It should be understood that provided values may optionally be configurable values in some embodiments.

In some embodiments, users may define alternative events or conditions as an alarm. Alarms may be able to be configured as be self-clearing (the alarm is cleared automatically when the alarm condition ends) or operator cleared (the alarm remains triggered until an operator clears it). A triggered alarm may generate one message when set and another when cleared (it does not continue to generate messages for the entire time the alarm condition is present). The current state of an alarm should be able to be read.

In some embodiments, the meter <NUM> may require suitable hysteresis to be implemented on alarm thresholds to prevent repeated triggering and clearing of alarms or repeated logging of events.

In some embodiments, the meter <NUM> may require being capable of maintaining an alarm state (triggered or not triggered) for each alarm and may provide a mechanism to clear the state.

Referring now to <FIG>, a method <NUM> of fluid monitoring is shown and described in further detail. Method <NUM> is executed by the at least one controller <NUM>, <NUM> to control operation of the one or more sensors <NUM>, <NUM>, or flow sensor <NUM> to sense a condition of a fluid in a lumen <NUM>.

In some embodiments of method <NUM>, at <NUM> the first controller <NUM> waits for a preconfigured time interval to expire before switching power to the at least one sensor <NUM>, <NUM>, <NUM>. The time interval of <NUM> may be user configured or a default value. After a time interval has expired in <NUM>, the first controller <NUM> switches power to the sensors <NUM> and waits for a "warm up" period for the at least one sensor <NUM>, <NUM>, <NUM>. This may comprise the at least one sensor powering up their own internal electronics, running their own operational diagnostics (if appropriate), and possibly indicating their operational state (e.g. properly operational or partially or fully non-operational). The interval timing may be aligned to hourly times based on the meter internal clock, or a timing defined from server <NUM>. Other time alignments may be used as required.

Once the one or more sensors <NUM>, <NUM>, <NUM> have warmed up, and assuming they are operational, the sensors <NUM>, <NUM>, <NUM> measure the relevant conditions and indicate at <NUM> a value of the condition they are configured to sense by providing a digital or analogue output signal to their configured controller <NUM>, <NUM> via cable <NUM>. The output signals from sensors <NUM>, <NUM>, <NUM> are converted from analogue to digital signals, if appropriate, and then interpreted and stored in a memory <NUM>, <NUM> for subsequent transmission to the server. During this time at <NUM>, any additional computation of the sensed data using algorithms may be applied, if appropriate.

At <NUM>, once the sensor measurements (i.e. output signals) have been received from sensors <NUM>, <NUM>, <NUM>, the first controller <NUM> discontinues supply of power from power supply <NUM> to sensors <NUM>, <NUM>, <NUM>. The first controller <NUM> processes the data derived from the output signals to compare measured values to preconfigured alarm condition levels. In some embodiments this process may be completed by the second controller <NUM>. At <NUM> the at least one controller <NUM>, <NUM> may set a binary flag indicating an alarm condition, for example.

If an alarm condition is detected, for example, because the sensed measurement exceeds or is equal to the alarm threshold for a particular sensor type, then the second controller <NUM> raises flag bits within the binary flag to indicate which alarm/s have been triggered. At <NUM>, data is stored in the at least one controller memory <NUM>, <NUM> to be stored upon expiration of the notification interval. This data may include typical payload data and/or alarm conditions.

At <NUM>, if the notification interval has expired, the first controller <NUM> causes the communications module <NUM> to be turned on (for example, by causing power supply <NUM> to supply power to communications module <NUM>) and an appropriate message to be transmitted to server <NUM> at <NUM>. If the notification interval has not expired, the first controller may wait until the notification has expired before proceeding to <NUM>. In some embodiments, the measurement interval in <NUM> may expire again before the notification interval in <NUM> expires. In such embodiments, data may be continually stored in <NUM> as discrete time-stamped entries without being overwritten.

Steps <NUM> and <NUM> may also be performed to send a notification message where lid sensor (not shown) on the water meter <NUM> detects the lid being opened or where some kind of fault in a sensor or telemetry unit <NUM> is detected.

The message sent to server <NUM> may include an identifier of the telemetry unit, a time stamp, an indication of one or more sensed values (if appropriate) and an alarm or notification type, for example. Meanwhile, until the notification interval expires at <NUM>, steps <NUM> to <NUM> may again be executed a number of times.

The notification interval may be a period of hours, for example such as four, six, twelve, twenty four, or another number of hours, while the measurement interval may be in the order of a few minutes, for example such as one, two, three, four, five, ten, twenty, thirty, forty, fifty, sixty or more minutes.

In some embodiments, the notification interval may be configured to expire on the detection of an alarm in <NUM>. In such embodiments, the detection of an alarm condition may trigger the transmittal of the alarm and/or the data payload. In one embodiment, users may configure the notification internal to expire, and for an alarm or data payload to be sent, upon detection of at least one alarm event. Such events may be the detection of one alarm condition, or a combination of alarm conditions.

Some embodiments of meter configurations, including suggested default sample intervals are detailed in the below table.

Referring now to <FIG>, a schematic cross-sectional representation of a vibration sensor <NUM> is shown and described in further detail. The vibration sensor <NUM> operates on a similar basis to sensor <NUM>, in that vibration sensor <NUM> has a sensor base <NUM> configured to abut or otherwise be positioned close to the flow tube <NUM> for receiving vibrations propagated from upstream (or downstream) conduits into the material of flow tube <NUM>. The sensor base <NUM> is arranged to propagate vibrational movement of a piezoelectric transducer <NUM> in response to the received vibrations. A seismic weight <NUM> is positioned on an opposite side of the piezoelectric transducer <NUM> from the sensor base <NUM>. Since the seismic weight <NUM> tends to remain relatively still due to its inertia, the piezoelectric transducer <NUM> is squeezed (between the seismic weight <NUM> and the sensor base <NUM>) by small compressions and bending moments arising from vibrations transmitted through the sensor base <NUM>. Such small compressions and bending moments result in a detectable current through (or voltage across) the piezoelectric transducer <NUM>. This current is detected as time varying electrical signals that can be sensed as an electrical output via conductors <NUM> that are coupled to electrodes <NUM> positioned on the piezoelectric transducer <NUM>.

The difference of vibration sensor <NUM> relative to vibration sensor <NUM> is that a variable compression element is employed in vibration sensor <NUM>, whereas an affixing shaft <NUM> is used in sensor <NUM>, which applies a static compression. This compression element may be in the form of a spring <NUM>, for example, that is arranged to exert a force on the seismic weight <NUM>, in order to place the piezoelectric transducer <NUM> in compression, as a rest state (i.e. when movement due to vibrations does not occur). The effect of having the piezoelectric transducer <NUM> in compression in a rest state provides for improved signal output quality detected on conductors <NUM> (as the electrical output of the piezoelectric transducer <NUM>) when vibration does occur.

The compression element may take various forms, but can include the spring <NUM> in the form of a coil spring, or may take other forms of spring, such as one or more leaf springs or a wave type spring (<NUM>, <FIG> and <FIG>), provided that the compression element acts to bias the seismic weight onto the piezoelectric transducer <NUM>. In some embodiments, the compression element may include one or more clamps or biasing devices arranged to provide a spring-like resilient biasing force on the seismic weight <NUM> (or other seismic weight embodiments described herein) in the direction of the piezoelectric transducer <NUM>.

In the arrangement shown in <FIG>, the vibration sensor <NUM> has a sensor housing <NUM> that is sized and arranged to fit over the spring <NUM>, seismic weight <NUM> and piezoelectric transducer <NUM> and to substantially enclose and/or retain those elements in place against the sensor base <NUM>. Although not shown in <FIG>, the housing <NUM> is removeably attachable to the sensor base <NUM> by attachment means, such as fasteners and/or clips or latches.

A top portion <NUM> of the housing <NUM> may have a registration formation <NUM> formed therein in order to assist in positioning (registering) the spring <NUM> against the top portion <NUM> of the housing <NUM>. The registration formation <NUM> may be in the form of a recessed area (or, in other embodiments, may comprise one or more projecting portions or flanges) in order to assist in properly positioning the spring <NUM> to be concentric and coaxial with the seismic weight <NUM> and the piezoelectric transducer <NUM>. The top portion <NUM> of the housing <NUM> also assists in providing a top bearing surface against which the spring can be braced in order to exert force against the seismic weight <NUM>.

The seismic weight <NUM> may be formed to be generally cylindrical, for example, with a lower portion <NUM> extending over and around a substantial portion of the piezoelectric transducer <NUM>, while leaving clearance space between a bottom surface <NUM> of the seismic weight <NUM> and the sensor base <NUM> against which the piezoelectric transducer <NUM> is biased. The clearance space allows for some degree of angular tilting of the seismic weight <NUM> relative to the sensor base <NUM> in response to certain kinds of vibrations. The seismic weight <NUM> has an upper portion 810b with a top face <NUM> being located toward to the top portion <NUM> of the housing <NUM>. The seismic weight <NUM> is shaped to define a bearing surface <NUM> at a shoulder position where the seismic weight transitions between the lower portion 810a and the upper portion 810b. The bearing surface <NUM> is arranged to be in contact with the lower end of the spring <NUM> in order to allow force from the spring to be transmitted through the seismic weight <NUM> and onto the piezoelectric transducer <NUM>. The cylindrical face of upper portion 810b of seismic weight <NUM> is arranged to be in contact with the inside helical face of spring <NUM> in order to assist in properly positioning the spring <NUM> to be concentric and coaxial with the seismic weight <NUM> and the piezoelectric transducer <NUM>.

Piezoelectric transducer <NUM> is preferably formed as a cylinder type transducer and may be formed of a PZT (lead zirconate titanate) or PVDF (polyvinylidene fluoride) piezoelectric material. The piezoelectric transducer <NUM> rests on the sensor base <NUM>, with a disc-shaped printed circuit electrode <NUM> positioned between the bottom of the piezoelectric transducer <NUM> and an upper surface of the sensor base <NUM>. The piezoelectric transducer <NUM> has a flat bottom and a flat top with a cylindrical shape in between and is held in place on a flat central area of the sensor base <NUM> by force applied to the upper flat end of the piezoelectric transducer <NUM> by the spring <NUM> pressing through the seismic weight <NUM>. A second disc-shaped printed circuit style electrode <NUM> is located at the top of the piezoelectric transducer <NUM> and may be the only thing separating the flat top surface of the piezoelectric transducer <NUM> and the corresponding flat recessed inner surface of the seismic weight <NUM> that bears down upon the piezoelectric transducer <NUM>.

A cavity is formed in the lower part 810a of the seismic weight <NUM> and defined by an inner cylindrical wall <NUM> of the seismic weight <NUM>. The cavity is coaxial and concentric with cylindrical parts of the seismic weight <NUM>. The cavity is sized to receive most (more than half, for example between about <NUM>-<NUM>%, optionally about <NUM>-<NUM>%) of the length of the piezoelectric transducer <NUM> but less than all of its length, while allowing a slight gap between the cylindrical wall <NUM> and the cylindrical outer surface of the piezoelectric transducer <NUM>. This slight gap <NUM> may have a radial width of about <NUM> to about <NUM>, for example, in order to allow room for a conductor to pass down one side of the piezoelectric transducer <NUM> from the top electrode <NUM>. In some embodiments, the gap <NUM> may be around <NUM> in regions where the conductor <NUM> is not present. The gap <NUM> does also allow for an insulating layer between the cylindrical outer surface of piezoelectric transducer <NUM> and the cylindrical wall <NUM> of the seismic weight <NUM>.

The dimensions of the electrodes <NUM> at the top and bottom of the piezoelectric transducer <NUM> are selected to be thin, and at the top electrode not radially larger than the piezoelectric transducer <NUM> (other than by a small margin of say <NUM>). The carrier material (i.e. a flexible substrate for carrying printed circuits or a thin fibre board commonly used for PCBs) of the electrodes <NUM> is selected to have electrical insulating properties, in order to avoid current passing between the piezoelectric transducer <NUM> and the sensor base <NUM>. In alternative embodiments, different kinds of electrodes can be employed as electrodes <NUM> and insulating properties can be provided by a separate thin insulating layer, rather than by the insulating material that carries the conducting parts of the electrodes <NUM>.

<FIG> and <FIG> illustrate embodiments of a vibration sensor <NUM> that is suited to be installed within a water meter assembly housing <NUM> so as to be able to sense vibrations propagating in the fluid conduit <NUM> of the water meter assembly <NUM>. The vibration sensor <NUM> operates in a substantially similar way to vibration sensor <NUM> in that it uses a biasing element to press the seismic weight <NUM> downwardly on to the piezoelectric transducer <NUM>, so that the piezoelectric transducer <NUM> is compressed between the seismic weight <NUM> and a sensor base <NUM>. However, vibration sensor <NUM> is different from vibration sensor <NUM> in that it uses a wave spring <NUM> as the biasing element, and in that the vibration sensor <NUM> comprises a dedicated local processing unit, for example in the form of a PCB (printed circuit board) <NUM> located within the housing <NUM>, in order to provide the functions of the processing unit <NUM>. In other words, the PCB <NUM> is configured to receive the output signals from conductor <NUM> that are coupled to receive electrical outputs from the piezoelectric transducer <NUM>, and to amplify, filter and process such output in order to determine whether the sensor vibrations indicate the presence of a fluid leak upstream of the position of the vibration senor <NUM>. Such a local processing unit arrangement may also be employed with embodiments of vibration sensor <NUM>.

The positioning of the PCB <NUM> within the housing <NUM> allows the vibration sensor <NUM> to be provided as a standalone unit for ready assembly into the meter assembly housing <NUM>. The sensor is configured to be mounted onto a mounting plate <NUM> of the fluid conduit <NUM> so that the sensor base <NUM> can receive vibrations propagated through the mounting plate <NUM>. The mounting plate <NUM> is formed as a flattened section extending generally tangentially to the diameter of the fluid conduit <NUM> and providing a flat mounting surface through which vibrations propagating into fluid conduit <NUM> can be readily transmitted into sensor base <NUM> when the sensor base <NUM> is mounted thereto in a parallel and abutting arrangement.

In various embodiments, the vibration sensor according to embodiments described herein can be coupled as a stand-alone device to another device that is not a water meter. For example, the vibration sensors described herein may be coupled with a data-logger and put into service independently of a meter or flow cell.

<FIG> additionally shows mounting fasteners <NUM> to couple the sensor base <NUM> to the mounting plate <NUM>, as well as further fasteners <NUM> (coupling fasteners) to couple the vibration sensor housing <NUM> onto the sensor base <NUM>.

The piezoelectric transducer <NUM> is similar to piezoelectric transducer <NUM> (i.e. cylinder-type PZT or PVDF), except that an insulating material <NUM> has been wrapped around the main portion of the cylindrical body of the piezoelectric transducer <NUM>. The insulating material <NUM> serves to reduce the potential for electric charge transmitting from the piezoelectric transducer <NUM> to the seismic weight inside the cavity defined by the inner wall <NUM> of the seismic weight <NUM>. The insulating material <NUM> is arranged to cover the conductor <NUM> that extends from the top electrode 915a downward along the cylindrical side of the piezoelectric transducer <NUM>.

A further difference of vibration sensor <NUM> over vibration sensor <NUM> is that a sealing ring <NUM> is positioned between the housing <NUM> and base plate <NUM> in order to seal the chamber defined between the housing <NUM> and the sensor base <NUM> against ingress of particulates or moisture.

An output wire bundle and/or connector <NUM> is coupled to the PCB <NUM> in order to provide data to an external device and receive power and control signals therefrom. The output wire bundle/connector <NUM> comprises <NUM> wires (though in different embodiments this number can be different) that are bundled together in an outer jacket of insulating material, that can also be used to act as a sealing cable gland to exit housing <NUM>. The output wire bundle may be terminated in the connector to facilitate connection to a board or a compatible connector in the water meter, without requiring soldering or the like. As shown in <FIG>, conductors <NUM> are coupled directly to an analogue front end <NUM> (<FIG>) on the PCB <NUM>, and the output wire bundle/connector <NUM> is coupled to a micro-controller <NUM> (<FIG>) carried by the PCB <NUM> and arranged to allow communication between the vibration sensor <NUM> and an external device.

<FIG> illustrates embodiments of a vibration sensor <NUM> that is suited to be installed within a water meter assembly housing <NUM> so as to be able to sense vibrations propagating in the fluid conduit <NUM> of the water meter assembly <NUM>. The vibration sensor <NUM> operates in a substantially similar way to vibration sensor <NUM> in that it uses a biasing element to press the seismic weight <NUM> downwardly on to the piezoelectric transducer <NUM> (which may be the same as the piezoelectric transducer <NUM>), so that the piezoelectric transducer <NUM> is compressed between the seismic weight <NUM> and a sensor base <NUM>. However, vibration sensor <NUM> is different from vibration sensor <NUM> in that it uses a coil spring <NUM> as the biasing element. Although not shown in <FIG>, the vibration sensor <NUM> may comprise a PCB <NUM> (as shown and described in relation to <FIG> and <FIG>) located within a part of a bracket <NUM> (that functions as a partial housing) and configured to provide the functions of the processing unit <NUM>. Sensor <NUM> may comprise a similar conductor and output wire bundle/connector arrangement as is described and shown in relation to vibration sensor <NUM>.

Additionally, vibration sensor <NUM> differs from vibration sensor <NUM> in that it has a seismic weight <NUM> of a different configuration and a top portion <NUM> of the bracket <NUM> has a downwardly projecting boss as the registration formation <NUM> for positioning the biasing element (spring <NUM>). A further difference lies in the sensor base <NUM> having a central recessed area that is recessed from a flat upper surface of the sensor base <NUM>. The central recessed area is sized to receive an electrode 915b and a lower part (e.g. a lower <NUM>-<NUM>%) of the piezoelectric transducer <NUM>.

The seismic weight <NUM> has a generally similar configuration to seismic weight <NUM>, with an upper face <NUM> spaced from the bracket top portion <NUM>, a lower face <NUM> spaced from the sensor base <NUM>, a lower portion 1110a having an inner wall <NUM> defining a cavity to receive the piezoelectric transducer <NUM>, and an upper portion 1110b. The upper portion 1110b defines an annularly recessed area with a bearing surface <NUM> that defines a surface against which a lower end of the spring <NUM> can exert a downward force. The inner cylindrical face of the annular recessed area of upper portion 1110b is arranged to be in contact with the inside helical face of spring <NUM> in order to assist in properly positioning the spring <NUM> to be concentric and coaxial with the seismic weight <NUM> and the piezoelectric transducer <NUM>.

The sensor <NUM> is configured to be mounted onto a mounting plate <NUM> of the fluid conduit <NUM> so that the sensor base <NUM> can receive vibrations propagated through the mounting plate <NUM>. The mounting plate <NUM> is formed as a flattened section extending generally tangentially to the diameter of the fluid conduit <NUM> and providing a flat mounting surface through which vibrations propagating into fluid conduit <NUM> can be readily transmitted into sensor base <NUM> when the sensor base <NUM> is mounted thereto in a parallel and abutting arrangement.

Vibration sensor <NUM> differs from vibration sensor <NUM> in that bracket <NUM> does not define an enclosed space and functions mainly as a means of securing and positioning the spring <NUM> to bias downwardly on the seismic weight <NUM>.

The piezoelectric transducer <NUM> may be substantially similar to piezoelectric transducer <NUM> (i.e. cylinder-type PZT or PVDF), with an insulating material <NUM> wrapped around the main portion of the cylindrical body of the piezoelectric transducer <NUM>. The insulating material <NUM> is arranged to cover the conductors (not shown in <FIG>) that extend from the top electrode 915a downward along the cylindrical side of the piezoelectric transducer <NUM>.

Other than the differences noted above, the vibration sensor <NUM> is substantially similarly configured and operates substantially similarly to vibration sensor <NUM>, <NUM>, and <NUM> as described herein.

<FIG> illustrate further embodiments of a vibration sensor <NUM> that is suited to be installed within a water meter assembly housing <NUM> so as to be able to sense vibrations propagating in the fluid conduit <NUM> of the water meter assembly <NUM>. The vibration sensor <NUM> operates in a substantially similar way to vibration sensors <NUM>, <NUM> and <NUM> in that it uses a biasing element to bias the seismic weight <NUM> downwardly on to a piezoelectric transducer <NUM> (which may be the same as the piezoelectric transducer <NUM> or <NUM>), so that the piezoelectric transducer <NUM> is compressed between the seismic weight <NUM> and a sensor base <NUM>. However, vibration sensor <NUM> is different from vibration sensor <NUM> in that it uses a coil spring <NUM> as the biasing element and because the coil spring <NUM> is arranged to pull the seismic weight <NUM> toward the sensor base <NUM> and onto the piezoelectric transducer <NUM>.

Although not shown in <FIG>, the vibration sensor <NUM> may comprise a PCB <NUM> (as shown and described in relation to <FIG> and <FIG>) located within a part of a housing (not shown but functionally similar to housing <NUM>, <NUM> or <NUM>) and configured to provide the functions of the processing unit <NUM>. Sensor <NUM> may comprise a similar conductor and output connector arrangement as is described and shown in relation to vibration sensor <NUM>, for example including conductors <NUM> coupled at one end to top and bottom printed circuit electrodes 1215a, 1215b and coupled at an opposite end to an electrical connector <NUM> that can couple to a PCB <NUM> or another external processing device.

Vibration sensor <NUM> may anchor the spring <NUM> to the sensor base <NUM> and the seismic weight <NUM> by fasteners, such as screws <NUM>, or other anchoring means. An adjustable set screw <NUM> is positioned in an axial bore through the seismic weight <NUM>. The set screw <NUM> can be manually adjusted to push (or not push) the seismic weight axially away from the piezoelectric transducer <NUM>, via a free movable spacer <NUM> that is disposed within the axial bore in between the set screw <NUM> and the piezoelectric transducer <NUM>, to allow the spring <NUM> to be placed under more (or less) tension and thereby apply more (or less) force to push the seismic weight <NUM> onto the piezoelectric transducer <NUM> applying compression thereto. The set screw <NUM> may be substantially fixed in position.

The seismic weight <NUM> is different from seismic weight <NUM>, <NUM> and <NUM> in that it does not receive the piezoelectric transducer <NUM> within an internal cavity. Instead, that cavity is defined by a part of the sensor base <NUM>. The seismic weight <NUM> needs to be axially aligned and generally axisymmetric and coaxial/concentric with the piezoelectric transducer <NUM> and give provision for the seismic weight <NUM> to be coupled to a suitable biasing element, such as spring <NUM>. The sensor base <NUM> needs to be axisymmetric with the piezoelectric transducer <NUM> and the seismic weight <NUM> so it can efficiently transmit to the piezoelectric transducer <NUM> vibrations from a surface it is coupled to.

Vibration sensors <NUM>, <NUM>, <NUM> and <NUM> operate according to similar principles to vibration sensor <NUM> in that all such sensors rely on the combination of a piezoelectric transducer positioned in between a sensor base and a seismic weight, with all of those three key elements being axially aligned. There is at least one conductor coupled to the piezoelectric transducer. Embodiments may use two such conductors. The sensor base, the piezoelectric transducer and the seismic weight are arranged so that relative movement between the sensor base and the seismic weight arising from a vibration source through the sensor base causes a current to be generated in the piezoelectric transducer and an output signal corresponding to the generated current is then detectable on the at least one conductor. In vibration sensor embodiments <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, the seismic weight <NUM>, <NUM>, <NUM>, <NUM>, <NUM> is preferably generally axisymmetric and is coaxial and concentric with the piezoelectric transducer <NUM>, <NUM>, <NUM>, <NUM>, <NUM> about the same central (longitudinal) axis defined through the centre of the piezoelectric sensor. Thus, the seismic weight <NUM>, <NUM>, <NUM>, <NUM>, <NUM> preferably has a round profile in plan view (e.g. as seen in <FIG>).

In the embodiment of vibration sensor <NUM>, the seismic weight <NUM> is connected to the sensor base <NUM>, in this case by the spring <NUM>. On the other hand, other embodiments, such as vibration sensors <NUM>, <NUM>, <NUM>, do not have the seismic weight and the sensor base connected to each other; rather, they are held in position relative to each other by the housing. The variable compression using a flexible biasing element in sensors <NUM>, <NUM>, <NUM> and <NUM>, versus the static compression using the pre-load of the affixing shaft <NUM> in sensor <NUM> assists in achieving increased sensitivity in detecting vibrations.

Other than the differences noted above, the vibration sensor <NUM> is substantially similarly configured and operates substantially similarly to vibration sensors <NUM>, <NUM> and <NUM> as described herein.

Referring now to <FIG>, the electrical arrangement employed in the vibration sensors <NUM>, <NUM>, <NUM> and <NUM> are described in further detail. Current and/or voltage signals detected via electrodes <NUM>, <NUM>, <NUM>, <NUM> on the piezoelectric transducer are received at analogue front end circuitry <NUM> by conductors <NUM>. The analogue front end circuitry <NUM> provides a half rail offset and amplifies signals in the frequency region of interest (i.e. up to <NUM>, and possibly up to <NUM> in some embodiments), while only using a single side supply. To achieve this, the signals received via conductors <NUM> are first biased with large value pull-up and pull-down resistors 1412a, 1412b and are then fed into the positive terminal 1415a of an operational amplifier <NUM>. The negative terminal 1415b of the operational amplifier <NUM> is driven by the output of the operational amplifier <NUM> that has been first fed through a low-pass filter <NUM>. Because of the inverse nature of the feedback-gain relationship, the analogue front end circuitry (AFE) <NUM> achieves an overall response of <NUM> for all DC signals (consisting only of the DC off-set introduced by the biasing resistors) and a gain that rapidly approaches a configurable amount for frequencies above DC.

Output signals <NUM> from the analogue front end circuitry <NUM> are received at an analogue-to-digital converter (ADC) <NUM> that may form part of microcontroller <NUM> forming part of the PCB <NUM> or may be separate from and connected to the microcontroller <NUM>. Thus, the amplified and filtered signals received on conductors <NUM> are converted by the ADC <NUM> into digital signals that are stored in a memory <NUM> of the microcontroller <NUM>. The memory <NUM> may comprise flash memory and random access memory (RAM), for example. An example microcontroller that can be used as microcontroller <NUM> is the STM32F091RB microcontroller from STMicroelectronics™, for example.

The ADC <NUM> samples the analogue output of the AFE <NUM> at a sampling rate that is twice the maximum frequency of interest during a predetermined sampling time period (set as a configuration parameter of the microcontroller <NUM>). The predetermined sampling time period may be set as the number of FFT sample frequencies divided by the sampling rate. Timer functions of the microprocessor <NUM> can be used for controlling the ADC sampling interval. The predetermined sampling time period may be in the range of between around <NUM> seconds to about <NUM> second, optionally about <NUM> seconds to about <NUM> seconds, for example. In some embodiments, the predetermined sampling time period may be about <NUM> seconds, for example.

The sampled signals from the AFE <NUM> are output from the ADC <NUM> to a processor <NUM> in the microcontroller <NUM> and are stored as digitised samples in memory <NUM>. The digitised samples are processed by the processor <NUM> executing a frequency analysis algorithm stored in a non-transitory part (i.e. flash) of the memory <NUM> of the microcontroller <NUM>. This algorithm involves the processor <NUM> performing a calculation of a fast Fourier transform (FFT) on the stored digitized samples. Using the complex values of the results from the FFT calculations performed by the processor <NUM>, the magnitude of each one of the complex amplitudes at each sampled frequency is then stored by the processor <NUM> in an array in the memory <NUM>. The processor <NUM> then scans the array of amplitude values to compare the amplitude values for specific frequency bands with predefined amplitude thresholds (stored in memory <NUM>) for those bands. If the magnitude in one or more specific frequency bands is above the predefined thresholds for the respective band and the amplitude thresholds of any other bands matching a certain frequency profile of a particular kind of fluid leak, then the microcontroller <NUM> sets an alarm flag or indication to indicate that the sensed vibrations indicate the presence of a fluid leak in the vicinity of the vibration sensor <NUM>.

In some embodiments, the processor <NUM> performs a single set (one or more) of comparisons to look for a specific frequency pattern associated with a known (previously experimentally determined, machine learned or otherwise determined) frequency signature for a particular leak. This set of comparisons may involve comparing the detected amplitude in a single frequency band against a single threshold amplitude value or it may involve comparing the detected amplitude in multiple frequency bands against multiple respective threshold amplitude values. In some embodiments, the processor <NUM> performs a series of comparisons in order to compare the sample data against a series of different frequency profiles associated with a series of distinct kinds of fluid leaks. In some embodiments, multiple threshold amplitude values may be applied to the same frequency band, for example where an amplitude above a lower threshold may indicate the likely presence of a leak and an amplitude above a higher amplitude in the same frequency band may indicate a leak of a certain magnitude (e.g. above a <NUM> diameter hole in a conduit within <NUM> metres from the location of the vibration sensor).

Once the processor <NUM> determines that an alarm flag is to be set, then the processor <NUM> stores an appropriate indication of this in memory <NUM> and then prepares an output data payload for storage and/or immediate transmission to the external device <NUM> via output connector <NUM>. The output data payload includes timing information, such as a timestamp of when the vibration sensor signals were received, any operational status indicators as to the functioning of the PCB <NUM> and optionally an indication of the type of leak detected (if the vibration sensor is configured to detect more than one leak type). In some embodiments, the data payload may include the stored array of amplitude values of the received signals at each frequency within the range of interest. The processor <NUM> is configured to receive power (e.g. <NUM> V DC) via the connector <NUM> and to receive commands, such as an operation (e.g. wake-up) command. Serial communications between the PCB <NUM> and the external unit <NUM> may also be provided by connector <NUM>.

In some embodiments, the processor <NUM> may effectively perform a rough analysis of the received signals to flag a possible leak or other condition, and the data payload may be provided to an external processing device, such as a server <NUM>, so that a final (or possible more accurate) determination can be made about the possible presence of a leak in the vicinity of the vibration sensor. For example, the server <NUM> may use data payloads received from multiple vibration sensors to determine the likely presence or absence of a leak. If the server <NUM> receives multiple alarm flags from meters or other devices coupled to neighbouring or closely spaced vibration sensors, then the server <NUM> may make a final determination that a leak exists in the vicinity of such vibration sensors.

Referring to <FIG> and <FIG>, some embodiments relate to a leak detection method <NUM> using vibration sensor <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> (described below). The method <NUM> comprises providing power to the vibration sensor <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> to enable measurements to be taken, at <NUM>. The method <NUM> further comprises initialising an iteration counter value and a leak counter value, at <NUM>. For example, the iteration counter value and the leak counter value may be set by processor <NUM>, <NUM> to an initial value of <NUM>.

At <NUM>, the iteration counter value is compared to a predetermined iteration limit. If the iteration counter value is less than or equal to the predetermined iteration limit, the iteration counter value is incrementally increased, at <NUM>. The iteration counter value may, for example, be increased by adding a value of <NUM> to the iteration counter value. If the iteration counter value is greater than the predetermined iteration limit, then method <NUM> stops. Method <NUM> may therefore be repeated a plurality of times equal to the iteration limit. The iteration limit may be set at a value between <NUM> and <NUM> iterations, for example, but can be configured to have a different value.

Vibrations propagated through fluid conduit materials from upstream locations are sensed by a piezoelectric transducer and corresponding electrical signals are received at analogue front end circuitry <NUM> by conductors <NUM>. An analogue voltage signal <NUM> from the analogue front end circuitry <NUM> is received and vibration data is recorded, at <NUM>. As discussed above, the signals may be sampled and converted into digitised data and vibration data may be stored in memory <NUM>. The vibration data may, for example, comprise voltage amplitude and frequency data.

In some embodiments, at least one of the iteration counter value, the leak counter value and vibration data may be stored in any one or more of memory <NUM>, <NUM>, volatile memory or non-volatile memory.

The analogue voltage signal <NUM> is passed through a low-pass filter to reduce or remove high-frequency signals. For example, frequencies above <NUM> may be filtered out.

In some embodiments, the analogue voltage signal <NUM> may be passed through a high-pass filter to reduce or remove low-frequency signals, at <NUM>. For example, frequencies below about <NUM> may be filtered out.

A Fast Fourier Transform (FFT) is then applied to the recorded data to separate a set of frequency bands approximating the frequency spectrum of the low-pass filtered signals, at <NUM>.

In some embodiments, the FFT transformed data is filtered to remove low frequency data, at <NUM>. For example, frequencies below about <NUM> may be deleted. In other embodiments, low frequency data (e.g. data relating to frequencies less than <NUM>) may be stored but ignored when FFT is applied. In some embodiments, the FFT is applied to recorded data over a frequency range of interest. For example, the frequency range of interest may be between about <NUM> to <NUM>.

The amplitude of the FFT data at each frequency is compared to an amplitude threshold, at <NUM>. If a threshold number of the amplitudes in the FFT data is greater than or equal to the amplitude threshold, then the leak counter value is incrementally increased, at <NUM>. The leak counter value may, for example, be increased by adding a value of <NUM> to the leak counter value. In some embodiments, the threshold number of amplitudes required to increment the leak counter may be one amplitude, i.e. if the amplitude at any frequency is greater than or equal to the amplitude threshold, then this indicates a potential upstream (or possibly downstream) leak and the leak counter value is incremented.

The amplitude threshold may, for example, be in the range of about <NUM> micro-Volt seconds to about <NUM> micro-Volt seconds, optionally about <NUM>µV. s to about <NUM>µV. s, and optionally about <NUM>µV. s to about <NUM>µV. In some embodiments, the amplitude threshold is about <NUM> micro-Volts seconds.

In some embodiments, only the FFT data over a frequency range of interest is compared to the amplitude threshold. For example, the frequency range of interest may be between about <NUM> to <NUM>. The frequency range of interest may be divided into frequency bands of equal range, for example, <NUM> or <NUM> bands.

At <NUM>, the leak counter value is compared to an alarm level. If the leak counter value is greater than or equal to the alarm level, then a detection flag is set to a 'yes' state to indicate that a leak has been detected, at <NUM>. The 'yes' state may, for example, correspond to a binary flag value of <NUM>. Method <NUM> is then stopped. The requirement of a leak counter being greater than the alarm level may advantageously reduce the occurrence of false alarms being raised as the amplitude must be greater than or equal to the amplitude threshold a number of instances before an alarm is raised. In some embodiments, the alarm level may be between <NUM> and <NUM> counts, optionally between <NUM> and <NUM> counts. In some embodiments, the alarm level may be <NUM> counts. The alarm level is less than the iteration limit.

In some embodiments, an alarm signal may be sent to a server <NUM> if the detection flag is set (but before the method <NUM> is stopped) to indicate that the detection flag is set. In other embodiments, the state of the detection flag is stored for later retrieval in a data payload by the server <NUM>. The alarm signal may be sent before, after or while the detection flag is set.

If the leak counter value is less than the alarm level, then an iteration period is waited, at <NUM>, before returning to step <NUM>. The iteration period may be between about <NUM> and about <NUM> minutes, for example. In some embodiments, the iteration period is about <NUM> minutes.

Referring to <FIG> and <FIG>, some embodiments relate to a leak detection method <NUM> using vibration sensor <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> (described below). The method <NUM> comprises providing power to the vibration sensor <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> to enable measurements to be taken, at <NUM>. The method <NUM> further comprises initialising an iteration counter value, a leak counter value and in some embodiments, a burst counter value, at <NUM>. For example, the iteration counter value, the leak counter value and the burst counter value may be set by processor <NUM>, <NUM> to an initial value of <NUM>.

At <NUM>, the iteration counter value is compared to a predetermined iteration limit. If the iteration counter value is less than or equal to the predetermined iteration limit, the iteration counter value is incrementally increased, at <NUM>. The iteration counter value may, for example, be increased by adding a value of <NUM> to the iteration counter value. If the iteration counter value is greater than the predetermined iteration limit, then method <NUM> stops. Method <NUM> may therefore be repeated a plurality of times equal to the iteration limit. The iteration limit may be set between <NUM> and <NUM> iterations, for example, but can be configured to have a different value.

In some embodiments, at least one of the iteration counter value, the leak counter value, the burst counter value and vibration data may be stored in any one or more of memory <NUM>, <NUM>, volatile memory or non-volatile memory.

The FFT data may be analysed to calculate an amplitude metric at <NUM>. The amplitude metric may be calculated over a frequency range of interest. For example, the frequency range of interest may be between about <NUM> and <NUM> or <NUM> and <NUM>. The amplitude metric represents the power or strength of the sensed signal.

In some embodiments, the amplitude metric may be, for example, an integration of the FFT data (integrating under the 'curve').

In some embodiments, the amplitude metric may be a root mean square (RMS) value for the FFT data over the frequency range of interest.

A detection ratio x is calculated by dividing the amplitude metric by a noise value, at <NUM>. The noise value is indicative of a background value for the metric where a leak would not be considered to be occurring. The noise value may be calibrated for each location where a vibration sensor is placed or may be generalised for a water supply network or a sub-network. For example, the noise value for the amplitude metric that is an RMS value may be <NUM> micro-Volt seconds.

The detection ratio x is then compared to a first detection threshold, at <NUM>. If the detection ratio x is greater than or equal to the first detection threshold, then the leak counter value is incrementally increased, at <NUM>. The leak counter value may, for example, be increased by adding a value of <NUM> to the leak counter value. In some embodiments, the first detection threshold may be in the range of about <NUM> to <NUM>, for example. In some embodiments, the first detection threshold may be about <NUM>.

The sensed vibration signal strength may be correlated with the severity of a leak. As the detection ratio x is indicative of the signal strength, it may be advantageously used to determine if the vibrations are indicative of a burst or very severe leak. In some embodiments, if the detection ratio x is greater than or equal to the first detection threshold, then the detection ratio x is further compared to a second detection threshold, at <NUM>. The second detection threshold is greater than the first detection threshold. If the detection ratio x is greater than or equal to the second detection threshold, then the burst counter value is incrementally increased, at <NUM>. The burst counter value may, for example, be increased by adding a value of <NUM> to the burst counter value. In some embodiments, the second detection threshold may be in the range of about <NUM> to about <NUM>, optionally about <NUM> to about <NUM>, for example. In some embodiments, the first detection threshold may be about <NUM>.

At <NUM>, the leak counter value is compared to a leak alarm level. If the leak counter value is greater than or equal to the leak alarm level, then a leak detection flag is set to a 'yes' state to indicate that a leak has been detected, at <NUM>. For example, setting the leak detection flag to 'yes' may correspond to setting a binary flag value to <NUM>. The method <NUM> is stopped after a leak detection flag is set. Requiring a leak counter value may advantageously reduce the occurrence of false alarms being raised as the detection ratio must be greater than or equal to the first detection threshold a number of instances before the alarm is raised. In some embodiments, the leak alarm level may be between <NUM> and <NUM> counts, optionally between <NUM> and <NUM> counts. In some embodiments, the leak alarm level may be <NUM> counts. The leak alarm level is less than the iteration limit.

In some embodiments, if the leak counter value is greater than or equal to the leak alarm level, then the burst counter value is compared to a burst alarm level (before stopping the method), at <NUM>. If the burst counter value is greater than or equal to the burst alarm level, a burst detection flag is set to a 'yes' state indicate that a burst has been detected, at <NUM>. For example, setting the burst detection flag to 'yes' may correspond to setting a binary flag value to <NUM>. The method <NUM> is stopped after a burst detection flag is set to 'yes'. In some situations, the leak detection flag and the burst detection flag may both be set to 'yes'. In some embodiments, the burst alarm level may be between <NUM> and <NUM> counts, optionally between <NUM> and <NUM> counts. In some embodiments, the burst alarm level may be <NUM> counts. The burst alarm level is less than the iteration limit.

In some embodiments, a leak alarm signal may be sent to a server <NUM> if the leak detection flag is set (before the method <NUM> is stopped) to indicate that the leak detection flag is set. A burst alarm signal may be sent to a server <NUM> if the burst detection flag is set (but before the method <NUM> is stopped) to indicate that the burst detection flag is set. The leak and burst alarm signals may be sent before, after or while the leak detection flag is set.

In other embodiments, the state of the leak and/or burst detection flags are stored for later retrieval in a data payload by the server <NUM>. In some embodiments, only a burst alarm signal is sent to the server <NUM> while the leak detection flag is stored for later retrieval.

As method <NUM>, <NUM> is limited to a set number of iterations, sensing and leak detection is also limited to a certain time period. This prevents sensing and leak detection from occurring over the entire predetermined time period. This is advantageous as it reduces energy consumption and timing can be selected to avoid noisy periods of time that correspond to peak water usage. By limiting the time over which method <NUM>, <NUM> occurs, spurious alarms may be reduced and alarms for slow and intermittent leaks may be reduced or avoided.

In some embodiments, the vibrations are sensed and vibration data is recorded for a predetermined length of time in method <NUM>, <NUM>. The predetermined length of time may be in the range of <NUM> seconds to <NUM> seconds, optionally about <NUM> seconds, for example.

In some embodiments, the vibrations are sensed and vibration data is recorded between a predetermined time period. The predetermined time period may, for example, be between midnight and <NUM> am. The predetermined time period may correspond with times that there is low background (ambient) acoustic and/or vibrational noise. Sensing and recording during the predetermined time period may therefore advantageously result in better signal-to-noise ratios for recorded vibration measurements.

In some embodiments, methods <NUM>, <NUM> are applied to leak detection at different locations using multiple separate vibration sensors, whether integrated into or connected with a water meter <NUM>. Different vibration sensors may sense and record data obtained from different locations. Signals from each of the different vibration sensors may be sent to a server <NUM> and an alarm may be raised only if an alarm signal, leak alarm signal or burst alarm signal is received from multiple vibration sensors.

The sensor housing of various embodiments of vibration sensors described above (e.g., sensors <NUM>, <NUM>, <NUM>) may be formed of a plastic material or suitable metal material. It is generally preferred that the sensor housing be sealed, for example using a waterproof seal such as a sealing ring <NUM>. For the biasing element applied in vibration sensors <NUM>, <NUM>, <NUM> and <NUM>, a stainless steel or spring steel spring (or multiple such springs) is considered suitable. The biasing element may have a spring constant in the range from <NUM> to <NUM> N/mm, optionally from <NUM> to <NUM> N/mm or <NUM> to <NUM> N/mm, for example. A suitable force on the seismic weight may be in the range of about <NUM> to about <NUM> newtons, for example.

The seismic weight can comprise or consist of a brass alloy or manganese bronze or other suitable density material. The mass of the seismic weight may be in the range of <NUM> grams to about <NUM> grams, for example. Optionally, the mass of the seismic weight may be in the range of <NUM> grams to <NUM> grams, for example.

The electrodes positioned at each opposite end of the piezoelectric transducer in sensors, <NUM>, <NUM>, <NUM> and <NUM> can be formed of either a rigid or flexible material, with a thickness ranging from about <NUM> to about <NUM>, for example. The conductive tracks may be printed on one side (the side facing the piezoelectric transducer) of the flexible material, with the other side comprising substantially insulating material, for example.

While the piezoelectric transducer of various embodiments can comprise a PVDF material, a PZT material may perform better under certain circumstances. For example, PZT columnar shaped piezo-ceramic material used for the piezoelectric transducer may have an example column diameter of about <NUM>. The piezoelectric material may have a piezoelectric voltage constant (g33) in the range of about <NUM> to about <NUM>. 03Vm/N, for example.

The sensor base may comprise a brass alloy or other metal that can be suitably flat and smooth, with a surface finish suited for optimal transfer of vibrations between the flow conduit <NUM> and the bottom or the piezoelectric transducer. In some embodiments, fasteners <NUM> used to couple the housing on to the sensor base may include, for example break-stem blind pop rivets, self-tapping screws for thermoplastics or machine screws and nuts. The fasteners <NUM> need to be able to clamp the sensor housing and base together against the spring force (e.g., <NUM> to <NUM> newtons) and the sealing force combined, and to be resistant to loosening due to vibrations.

Referring to <FIG>, further embodiments of a vibration sensor <NUM> are shown and described. The vibration sensor <NUM> is substantially the same in operation, structure and function as vibration sensor <NUM>, with the primary difference being that a different electrical conductor configuration is used to sense the electrical output of the piezoelectric transducer <NUM>. Like reference numerals are used among the drawings to indicate the same physical features or functions as between the vibration sensor <NUM> and the vibration sensor <NUM>.

The vibration sensor <NUM> uses a printed circuit board <NUM> that has a rigid component <NUM> and a flexible component <NUM>. The flexible component <NUM> comprises a flexible coupling portion <NUM> that acts as a bridge between the rigid printed circuit component <NUM> (that houses the main electrical circuits as shown in <FIG>) and a foldable portion of the flexible printed circuit <NUM>. The foldable portion is arranged to partially surround and contact the top and bottom surfaces of the piezoelectric transducer <NUM> in order to sense the electrical output thereof. In addition to the abovementioned differences from vibration sensor <NUM>, vibration sensor <NUM> may employ a gasket <NUM> (instead of the sealing ring <NUM>) for sealing the internal chamber of the vibration sensor <NUM> against the ingress of water or gas. Additionally, the top housing part <NUM> is slightly different from housing part <NUM>, with an electrical connector passage defined at one end to extend close to the base plate <NUM>. Different fasteners, such as bolts or screws <NUM> may also be employed.

<FIG>, <FIG> illustrate the printed circuit component <NUM> in further detail. <FIG> shows the flexible printed circuit portion <NUM> in a folded configuration and <FIG> shows how the piezoelectric transducer <NUM> is situated to be partially wrapped by the flexible printed circuit component <NUM>. The flexible printed circuit portion <NUM> comprises a lower portion <NUM> and an upper portion <NUM> joined by a second coupling portion <NUM> that extends between the lower portion <NUM> and upper portion <NUM>.

The lower flexible printed circuit portion <NUM> has a base <NUM> with an upper side 1784A that has exposed conductive material (that may be gold plated, for example) thereon for receiving electrical potential variations (in the form of current and voltage) arising from electrical contact with the bottom of the piezoelectric transducers <NUM>. The base <NUM> also has a rigid bottom disc or plate portion 1784b (for example, formed of fibreglass "FR-<NUM>") that is an electrical insulator but which is rigid enough to transmit vibrations propagated through the sensor base <NUM> without substantial attenuation. The lower flexible printed circuit portion <NUM> also has folding fingers or wings <NUM> that are deformable from a flat configuration (see <FIG>) to a folded configuration (see <FIG>) in order to shield a lower part of the piezoelectric transducer <NUM> from contact with an inner surface of the seismic weight <NUM>.

The upper flexible printed circuit part <NUM> has a generally flat top portion <NUM>, which has a lower (inner) surface 1794A with exposed electrically conductive material (e.g., gold plated) and has a rigid insulating disc or plate portion 1794b on the upper (outer) face thereof. Similar to the lower portion <NUM>, the upper portion <NUM> has a plurality of fingers or wings <NUM> that can fold by bending or deforming to at least partially cover an upper part of the outside cylindrical wall of the piezoelectric transducer <NUM> to shield it from electrical contact with an inner wall of the seismic weight <NUM>.

As seen best in <FIG>, the flexible printed circuit <NUM> has conductors printed thereon and extending from the top portion <NUM> and the bottom portion <NUM> to the rigid printed circuit board component <NUM>. In order to avoid the conductors for the top portion <NUM> interfering with or crossing the conductors of the bottom portion <NUM>, a first conductor (or set of conductors) 1796a is coupled to the conductive area of the conductive lower surface 1794a of the top portion <NUM>. The first conductor 1796a extends along an inner wall of coupling portions <NUM> without extending all the way to the lower portion <NUM>. Instead, to continue to conduct electrical signals, the first conductor 1796a couples to further first conductors 1796b on an opposite side of the second coupling portion <NUM> by conductive through holes (not shown). The first conductors 1796B then pass between the plate or disc 1784b and the upper conductive surface 1784a of the bottom portion <NUM>, with the first conductor 1796b continuing on the underside of first coupling portion <NUM> to finally couple (via through holes) to electrodes <NUM> carried on the relatively rigid substrate <NUM> of the rigid PCV portion <NUM>. The second conductors <NUM> extend on a side of coupling portion <NUM> opposite from conductors <NUM> directly from the upper conductive surface 1784a of the bottom portion <NUM> to electrodes or other circuit components on the relatively rigid substrate <NUM>.

As shown in the drawings, the upper set of fingers <NUM> are arranged in a spaced array which, together with the second coupling portion <NUM> that extends like a strip between the top portion <NUM> and the bottom portion <NUM>, serves to generally avoid contact between the material of the piezoelectric transducer <NUM> and the inside wall of the seismic weight <NUM> (or other seismic weights described herein). A different arrangement of protective fingers or wings <NUM> is provided extending from the lower portion <NUM> which, together with the strip material of the coupling portion <NUM>, also serves to shield the piezoelectric transducers <NUM> from contact with the seismic weight <NUM>.

Use of a single printed circuit board <NUM> that has a flexible component <NUM> and a rigid component <NUM> allows for improved ease and efficiency of assembly of the piezoelectric transducer and electronic interface circuitry with the seismic weight <NUM> and the housing <NUM> and sensor base <NUM>. Both the bottom and top insulating discs or plates 1784B and 1794B are selected to be of sufficiently rigid material to substantially avoid dampening vibrations transmitted through the base plate <NUM> and thereby substantially avoid dampening relative movement between the piezoelectric transducer and the seismic weight <NUM>.

<FIG> shows a further schematic circuit diagram to illustrate an alternative circuit layout for the printed circuit board assembly <NUM>, shown in the embodiment of <FIG> as printed circuit board assembly <NUM>. Analogue front end <NUM> shown in <FIG> is generally analogous to the analogue front end <NUM> shown in <FIG>, but for a slight difference in arrangement (and values) of the output resistors and capacitors. The electrical conductors <NUM> and <NUM> shown in <FIG> provide the input to the analogue front end <NUM>. A microcontroller unit <NUM> is provided in the printed circuit board assembly <NUM> and is similar in function to the microcontroller <NUM> as described above. Power control circuitry <NUM> is further comprised in the printed circuit board assembly <NUM> and allows for receipt of a wakeup signal from an external controller, such as the water meter controller <NUM>. Separate circuitry (not shown) may be provided for enabling communication between the microcontroller <NUM> and an external controller.

Claim 1:
A water meter system (<NUM>) to be installed in-line with a fluid conduit (<NUM>) comprising:
a flow tube (<NUM>) having a hollow internal space (<NUM>) to receive and conduct fluid flow;
a controller (<NUM>) having a processor (<NUM>);
a sensor installation (<NUM>) comprising:
a flow sensor (<NUM>) for sensing fluid flow (<NUM>) in the conduit (<NUM>); and
a vibration sensor (<NUM>) to detect vibrations in the upstream fluid conduit (<NUM>) and transmit vibration data to the controller (<NUM>),
characterised in that the controller (<NUM>) is configured to use a sensed characteristic of the fluid flow from the flow sensor (<NUM>) in conjunction with the vibration data to identify a leak condition of the fluid conduit (<NUM>);
wherein the vibration sensor (<NUM>) comprises:
a piezoelectric transducer (<NUM>); and
a base (<NUM>) connected to a seismic weight (<NUM>) and in abutment with the flow tube (<NUM>) for receiving vibrations propagated from the fluid conduit (<NUM>), wherein the base (<NUM>), seismic weight (<NUM>) and piezoelectric transducer (<NUM>) are axially aligned, and
wherein the water meter system further comprises upstream and downstream coupling portions (<NUM>) to couple the water meter system to the fluid conduit (<NUM>) and a spring (<NUM>) that acts to bias the seismic weight (<NUM>) onto the piezoelectric transducer (<NUM>).