WO2019155222A1

WO2019155222A1 - Device and method for sensing the level of naturally-occurring water, and method for installation of such a device

Info

Publication number: WO2019155222A1
Application number: PCT/GB2019/050340
Authority: WO
Inventors: Ian BARTHOLOMEW; Adam RIMMER; Charles Cooke
Original assignee: Floodflash Ltd
Priority date: 2018-02-07
Filing date: 2019-02-07
Publication date: 2019-08-15
Also published as: GB2570963A; GB201801990D0; GB2578564A; GB201816464D0

Abstract

There is provided a device for sensing the level of flood water, comprising at least one test chamber having an opening through which flood water may enter, one or more air pressure wave generating elements, configured to generate air pressure waves within said at least one test chamber, one or more air pressure wave sensors, configured to detect air pressure waves present within the at least one test chamber; and control circuitry, coupled to said one or more air pressure wave generating elements, said one or more air pressure wave sensors. The device configured to cause said one or more air pressure wave generating elements to generate air pressure waves within the at least one test chamber, at least some of which are reflected by flood water that has entered the test chamber, and to determine the level of such flood water present within the test chamber, based on the resulting output from said one or more air pressure wave sensors, including the output corresponding to said air pressure waves reflected as a result of the flood water. The device is mounted on a wall of a building.

Description

DEVICE AND METHOD FOR SENSING THE LEVEL OF NATURALLY-OCCURRING WATER AND METHOD FOR INSTALLATION OF SUCH A DEVICE

FIELD OF THE INVENTION

The following disclosure relates to devices and methods for sensing the level of naturally- occurring water, in particular water present on land or in bodies of water. More particularly, it relates to devices and methods for sensing the level of flood-water, i.e. water that submerges land that is usually dry. It also concerns methods for installing such devices for sensing the level of such naturally-occurring water and, in particular, flood-water.

BACKGROUND

The water level of rivers, lakes, reservoirs and the like is monitored in various locations. This information can be used to determine a flooding risk level for a particular site and for any buildings nearby. However, given complex and often localised conditions and geography it can be difficult to assess whether a specific site or building has actually flooded without inefficient and costly in-person surveying. For instance, in some cases it has been known for houses on the same street to have different flood outcomes, where one has flooded, and another has not.

Accordingly, there is a need for devices and methods that can provide simple and effective sensing of the level of flood-water, particularly in buildings to determine if a building has flooded.

SUMMARY

Aspects of the invention are set out in the appended independent claims, whereas particular embodiments are set out in the appended dependent claims.

The following disclosure, in a first aspect, relates to a device for sensing the level of flood- water, the device comprising: at least one test chamber having an opening through which flood water may enter; one or more air pressure wave generating elements, configured to generate air pressure waves within said at least one test chamber; one or more air pressure wave sensors, configured to detect air pressure waves present within the at least one test chamber; and control circuitry, coupled to said one or more air pressure wave generating elements, said one or more air pressure wave sensors. The control circuitry is configured: to cause said one or more air pressure wave generating elements to generate air pressure waves within the at least one test chamber, at least some of which are reflected by flood water that has entered the test chamber; and to determine the level of such flood water present within the test chamber, based on the resulting output from said one or more air pressure wave sensors, including the output corresponding to said air pressure waves reflected as a result of the flood water, wherein the device is mounted on a wall of a building.

In a further aspect, the disclosure relates to a method of sensing the level of flood-water comprising: providing a device attached to the interior wall of a building; where the device comprises at least one test chamber, which has an opening through which flood water may enter; generating air pressure waves within said at least one test chamber, flood water that has entered said at least one the test chamber causing the reflection of at least some of said generated air pressure waves; detecting air pressure waves present within the at least one test chamber, including said air pressure waves reflected as a result of flood water that has entered the at least one test chamber; and determining the level of flood water present within the at least one test chamber based on the detected reflected air pressure waves.

In a still further aspect, the disclosure relates to a method for installing a device for sensing the level of flood-water, comprising the steps of: providing a device according to one of the embodiments described herein; fixing the device to a wall of a building, thus resulting in the device having a fixed elevation; and storing data relating to said fixed elevation.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now directed to the accompanying drawings, in which:

Figure 1 is a schematic diagram of a device for sensing the level of flood-water according to an illustrative embodiment, where the device is situated in an area experiencing a flood;

Figure 2 is a schematic diagram of the device of Figure 1 , where the device is situated in an area that is not experiencing a flood;

Figure 3A is a view of the cross section indicated by line 3A in Figure 2, taken through the chamber of the device of Figures 1 and 2;

Figure 3B is a view of the cross section indicated by line 3B in Figure 2, taken through the chamber of the device of Figures 1 and 2;

Figure 4A shows an alternative shape for the cross section of the chamber indicated by line 3A in Figure 2.

Figure 4B shows an alternative shape for the cross section of the chamber indicated by line 3B in Figure 2. Figure 5 is a schematic diagram of a device for sensing the level of flood-water according to a further illustrative embodiment, in which the device has a tapered test chamber.

Figure 6A is a view of the cross section indicated by line 6A in Figure 5, taken through the chamber of the device;

Figure 6B is a view of the cross section indicated by line 6B in Figure 5, taken through the chamber of the device;

Figure 7 is a schematic diagram of a device for sensing the level of flood-water according to a still further illustrative embodiment, where the device has both a test chamber and a reference chamber;

Figure 8A and Figure 8B are, respectively, a front view and a side view of the device of Figure 7 installed on a wall or other vertical surface, such as a wall of a building, particularly the interior wall of a building;

Figure 9 is a graph representing a series of air pressure wave pulses produced by an air pressure wave generating element, and a resulting series of air pressure wave pulses received by an air pressure wave sensor;

Figure 10 is an exploded view of a device for sensing the level of flood-water according to yet another illustrative embodiment, which includes various features that assist its mounting to the wall of a building;

Figure 1 1 is a partially exploded view of the device of Figure 10;

Figure 12 is a perspective view of the device of Figures 10 and 1 1 , once assembled;

Figure 13 is a front view of the device of Figures 10 to 12, once assembled;

Figure 14 is a side profile view of the device of Figures 1 1 to 13, once assembled;

Figure 15 is a flow-diagram illustrating a method of sensing the level of flood water according to an illustrative embodiment; and

Figure 16 is a flow-diagram illustrating a method for installing a device for sensing the level of flood-water according to an illustrative embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS The following disclosure details various illustrative embodiments of a device for sensing the level of flood-water, as well as illustrative embodiments of a method for installing such a device, and methods for sending the level of flood-water.

The devices and methods disclosed herein may be utilised by an insurance service provider so as to measure the level of flood-water, with pay-outs, insurance premia, and/or flooding risk being determined using the resulting data. For instance, an insurance service provider might utilise the flood-level data to determine whether the flood-level at a customer site has exceeded a predetermined threshold and, if so, to arrange for a pay-out to be made to the customer. Such a pay-out might be made automatically, for instance where the data is transmitted regularly to the insurance provider. In any case, arranging payment based on such a threshold being exceeded may simplify and expedite the claim settlement process, allowing the customer to more quickly recover from the flood.

The devices and methods disclosed herein may also be of benefit to building owners (whether the building is a commercial premises or a home) or to public organisations (such as environmental agencies).

Devices as described herein may be configured to operate autonomously (e.g. taking readings substantially without user input or involvement), so that they can be deployed in remote locations. For example, the device may be located on the interior surface of a wall of a building. As such, the device measuring the level of water may be able to determine the level of flood water within the interior of the building.

Devices for sensing the level of flood-water

Reference is firstly directed to Figure 1 , which is a schematic diagram illustrating a device 101 for the sensing of the level of flood-water according to an illustrative embodiment.

As shown in Figure 1 , the device includes a test chamber 103. As is apparent, the test chamber has an opening 123 through which flood water 121 may enter. In the particular example shown, the opening 123 is located at the bottom of the test chamber; however, it may be provided at any suitable location, such as in the side of the chamber 103. Furthermore, although only one test chamber 103 is shown, there may be any appropriate number of test chambers, e.g. two, three, four, etc.

As is also shown in Figure 1 , the device further includes an air pressure wave generating element 105. This element 105 is configured to generate air pressure waves within the test chamber 103. Although only one air pressure wave generating element 105 is shown, several such elements may be used, such as two, three or four air pressure wave generators. The (or each) generating element 105 may, for example, comprise a piezoelectric member to which a drive waveform is applied, causing the piezoelectric member to oscillate and thus produce air press+ure waves. In another example, the (or each) generating element 105 may comprise a voice coil, to which a drive waveform may likewise be applied in order to generate air pressure waves. Nonetheless, these are merely illustrative examples and any suitable type of generating element 105 may be employed.

As is also visible in Figure 1 , the device 101 further includes an air pressure sensor 107. This sensor 107 is configured to detect air pressure waves within the test chamber 103. Although only one sensor is shown, any suitable number of sensors may be employed for detecting the air pressure waves 1 17 in the test chamber 103, or test chambers, where there are several. Similarly to the generating element 105, the (or each) sensor 107 may, for example, comprise a piezoelectric member, which vibrates in response to air pressure waves, with such vibrations producing a voltage within the piezoelectric member that can be read off. In another example, the (or each) sensor 107 may comprise a voice coil, whose movements as a result of air pressure waves produce a voltage that can be read off.

As illustrated schematically in Figure 1 , the device 101 also includes control circuitry 109. This control circuitry 109 is configured to cause the air pressure generating element 105 to generate air pressure waves 1 17 within the test chamber 103, for example, by sending signals via connection 1 13, as illustrated in Figure 1. Where flood water 121 has entered the test chamber 103 through the opening 123, as is the case in Figure 1 , at least some of the air pressure waves generated by the air pressure generating element 105 are reflected by such flood water 121. Figure 1 shows such air pressure waves 1 19 that have been reflected as a result of the flood water 121 within the chamber 103. As will be appreciated, such reflected air pressure waves 1 19 may, in due course, be detected by the air pressure sensor 107.

The control circuitry 109 is further configured to determine the level of the flood water 121 present within the test chamber 103, based on the resulting output from the air pressure wave sensor 107, including the output corresponding to the air pressure waves 1 19 reflected as a result of the flood water 121 .

There are a number of ways in which this determination may be performed. For example, the control circuitry may compare the timing and/or amplitude of the air generated pressure waves 1 17 with that of the reflected air pressure waves 1 19.

In some embodiments, the device 101 (and, more particularly, the control circuitry 109) may be described as using acoustic location to determine the level of the flood water 121 present within the test chamber 103. In certain such embodiments, such as that described herein with reference to Figure 9, the device 101 may be described as using time-of-arrival localization.

The control circuitry 109 may be configured such that the determination may yield a specific value for the level of the flood water 121 ; however, it might instead be configured such that the determination is binary, simply indicating whether the level of flood water is above or below a predetermined level.

To carry out the determination of the level of the flood water 121 present within the test chamber 103, the control circuitry may include logic circuitry, such as a microprocessor (though the determination could instead be performed using analogue circuity, or any other suitable alternative arrangement).

Various operating frequencies for the air pressure wave generating element 105 may be suitable, depending on the particular embodiment. In some embodiments, the air pressure waves generated by the air pressure wave generating element 105 may, for example, be sound waves (though in other examples, the air pressure waves may be in the ultrasound range, or, indeed, of any suitable frequency).

Testing carried out by the inventors indicates that an energy efficient device may be provided where the pressure waves generated by the air pressure wave generating element have a frequency of between 50Hz and 20 KHz, and in some cases between 2 KHz and 8 KHz. Such frequencies were found during such testing to be only moderately attenuated within a test chamber 103, thus allowing the generating element to be driven at lower power.

In addition, or instead, the control circuitry 109 may be configured to cause the air pressure wave generating element 105 to operate at its resonant frequency. A possible consequence of this is that the device 101 requires less power to operate and thus this may again provide an energy efficient device.

In some embodiments, the control circuitry 109 may be configured to apply a drive waveform to the air pressure wave generating element 105 that is an impulse (i.e. is approximately a delta function). Such control circuitry 109 may be simple, yet may yield reliable detection of the flood-water level.

Although Figure 1 shows the generating element 105 and sensor 107 as being separate components, it should be understood that in other embodiments these may share various common components, or, indeed, that a single component may act as both the generating element 105 and the sensor 107 (i.e. rather than utilising a separate air pressure wave transmitter and receiver, the device may include an air pressure wave transceiver). For example, the generating element 105 and sensor 107 might share a piezoelectric member or voice coil that is used to both generate (transmit) air pressure waves and to sense the presence of (receive) air pressure waves.

Returning now to Figure 1 , as illustrated therein, the test chamber 103 may be elongate, for instance having a length that is substantially greater than its width/diameter. Testing carried out by the inventors indicates that an elongate test chamber 103 may, in at least some cases, result in a high accuracy for the determination of the level of flood water (possibly as a result of multipath effects being of small magnitude, or even negligible).

Testing carried out by the inventors indicates that a length of between about 0.5m and 5m for the test chamber is suitable in some cases, giving a good level of accuracy for the determination of the level of flood water without requiring a high level of power consumption (e.g. to generate sufficiently powerful pressure waves so as to overcome attenuation within a large test chamber), and/or requiring complex sensors and/or control circuitry (e.g. to detect particularly attenuated reflected pressure waves or reflected pressure waves that arrive very shortly after the production of pressure waves by the generating element).

Additional testing by the inventors indicates that a width of between about 3mm and 25mm for the test chamber is suitable in some cases, giving a giving a good level of accuracy for the determination of the level of flood water without requiring complex sensors and/or control circuitry (e.g. to account for multipath effects).

Such testing may therefore be understood as indicating that a suitable test chamber may, in some cases, have a length that at least 20 times greater than its width and, in more specific examples, have a length that is at least 100 or even 1000 times greater than its width.

Nonetheless, it will be appreciated that such dimensions are only illustrative and that the test chamber 103 may have any suitable dimensions. Indeed, it is by no means essential that the test chamber 103 is elongate; it may have any suitable shape that enables the level of flood water present within the test chamber to be determined.

On the other hand, in embodiments, such as that shown in Figure 1 , where the test chamber 103 is elongate, both the air pressure wave generating element 105 and the air pressure wave sensor 107 may be located at or adjacent a first longitudinal end of the test chamber 103 (in the particular example shown in Figure 1 , the top end). Devices according to such embodiments may be configured for operation with the first longitudinal end of the test chamber vertically above the opening 123 in the chamber. Furthermore, as illustrated in Figure 1 , the opening 123 may be located at or adjacent a second, opposing longitudinal end of the test chamber 103 (in the particular example shown in Figure 1 , the bottom of the device). Flence (or otherwise), the device 101 may be configured for operation with the first longitudinal end of the test chamber (where the air pressure wave generating element 105 and the air pressure wave sensor 107 are located) vertically above the second longitudinal end (where the opening 123 is located).

In some embodiments, such as that depicted in Figure 1 , the test chamber 103 may be provided at least in part, and preferably substantially, within an elongate member 108. In such embodiments, the same opening 123, through which flood is able to enter the test chamber 103, may additionally extend through the elongate member 108, as is shown in Figure 1. Further, in embodiments, such as that of Figure 1 , where the test chamber 103 is elongate, the elongate member 108 may extend in the same direction as the elongate test chamber 103 (e.g. their lengths may be parallel). In terms of its construction, the elongate member 108 may be substantially integrally-formed, for instance by a moulding process (e.g. by extrusion or injection moulding). Such an integrally-formed elongate member 108 may not, for example, have within it any welding, adhesive or other joints and/or may be formed from a generally homogeneous material. In some embodiments, the elongate member 108 may conveniently be formed generally of a polymeric material; for instance, at least the structure of the elongate member 108 may substantially consist of polymeric material.

In terms of its form, the elongate member 108 may comprise a series of markings on its exterior surface (not shown) that provide a distance or volume scale for the test chamber. Such markings may, for example, be distributed along the length of the elongate member 108. Such a scale may assist in installation of the device. For instance, providing such a scale on the elongate member 108 may facilitate the provision of an elongate member of desired size, for example by cutting an elongate member with such a scale to a desired length.

As illustrated in Figure 1 , which indicates the vertical direction with arrow V, the device 101 may be configured to be mounted with the elongate member arranged substantially vertically (though conceivably it could be configured to operate with the elongate member angularly spaced from the horizontal by some predetermined angle other than 90 degrees). The control circuitry 109 and associated components, such as the generating element 105 and sensor 107, may be configured for operation with the device in this orientation.

In some embodiments, such as that shown in Figure 1 , the device 101 may further include a housing 1 1 1 that contains the control circuitry 109, the air pressure wave generating element 105 and the air pressure wave sensor 107. The housing 1 1 1 may seal the control circuitry in a water-resistant manner, for example so as to protect the control circuitry from damage by flood water. As shown in Figure 1 , where the device includes an elongate member 108, one of its longitudinal ends may be received within this housing.

It should however be understood that such a housing 1 1 1 is by no means essential, and that various other ways of mounting the control circuitry 109, air pressure wave generating element 105, and the air pressure wave sensor 107 within the device are suitable.

In some embodiments, the device may include a transmitter (not shown) that is connected to the control circuitry 109. The control circuitry 109 may be configured to cause this transmitter to transmit data relating to the level of flood water, as determined by the control circuitry 109. The transmitter may enable such water-level data to be sent to a server (or other external device) and/or to be uploaded to the cloud. For example, the transmitter may transmit such data wirelessly, via electromagnetic radiation, such as by connecting to a cellular network(e.g. by utilising GSM, 3G, 4G, and/or 5G), though it could instead be configured to utilise Bluetooth, or Wi-Fi.

The control circuitry 1 1 1 may be configured to periodically take readings of the level of flood- water (in the manner described above) and to cause the transmitter to transmit data relating to a number of such readings. The frequency at which such readings are taken may be substantially higher than the frequency at which data is sent by the transmitter. Flence (or otherwise), data for multiple readings may be sent in each transmission. A possible consequence of reducing the frequency of data transmissions is that less power is consumed by the device.

It should however be appreciated that the inclusion of a transmitter within the device is not essential. For example, data relating to the level of flood water may instead, or in addition, be stored on data storage on-board the device and then downloaded by means of a physical connection with the device, such as a lead plugged into the device 101.

In some embodiments, the device may include data storage for storing historic water-level data. Where, as described above, the device includes a transmitter or is configured to provide a physical connection to another device, such data (or portions thereof) may be downloaded periodically and/or on demand. In addition (or instead), the control circuitry 109 may be configured to perform analysis of such historic data, for example so as to identify anomalous trends in the determined flood-water level (e.g. that the level is changing at an unusually fast rate). Turning now to the operation of the device 101 of Figure 1 , it should be understood that the air pressure wave generating element(s) 105 may be driven according to various strategies. Nonetheless, for the purposes of illustration, one particular way in which the device of Figure 1 may be configured for operation will now be described with reference to Figure 9.

In the illustrative embodiment that will be described with the aid of Figure 9, the control circuitry 109 is configured to cause the air pressure wave generating element 105 to generate a series of one or more pressure pulses. The control circuitry 109 may then determine the level of flood water present within the test chamber based on the time interval from the generation of the series of pressure pulses to the detection of the corresponding reflected air pressure waves by the air pressure wave sensor. In some cases, the thus- configured device 101 may be described as using time-of-arrival localization to determine the level of flood-water present within the test chamber.

Reference is now directed to Figure 9, which is a graph of the air pressure within the test chamber 103 of the device of Figure 1 at a location adjacent the generating element 105 and sensor 107. The graph of Figure 9 represents an idealised situation, where there is negligible background noise, so as to illustrate clearly the principles of operation of the illustrative embodiment of the device. Figure 9 shows pressure oscillations corresponding to a series of three successive air pressure pulses 980 generated by the air pressure generating element 105. These may, for example, be produced as a result of the control circuitry 109 applying a drive waveform to the air pressure wave generating element 105 that comprises one or more drive pulses. In some embodiments, the drive waveform may include a respective drive for each air pressure pulse generated by the generating element.

Figure 9 shows further pressure oscillations 982 that result from the three previously generated pressure pulses 980 being reflected by flood-water in the test chamber 103 and arriving back at the sensor 107. The control circuitry 109 may be configured to detect these reflected air pressure waves 982 and to determine the time interval 984 from the generation of the series of pulses 980 by the generating element to the detection of the reflected air pressure waves 982 by the sensor 107.

Using the thus-determined value for this time interval 984, the control circuitry 109 may determine the level of flood-water present within the test chamber 103. For instance, the control circuitry 109 may determine a value for the distance travelled by the reflected pressure waves 982, using this time interval 984 and a value for the speed of travel of air pressure waves, the speed of sound, within the test chamber 103. It should be noted that the term“speed of sound” is used generally herein and does not imply that the air pressure waves have a particular frequency; thus they may be at ultrasound or sound frequency. The speed of sound value utilised by the control circuitry 109 may be a stored value corresponding to typical operating conditions, may be a value calculated based on locally measured temperature and/or pressure values (or values for other variables affecting the speed of sound), or may be a value determined empirically by the device 101 (e.g. as part of a calibration performed by the device 101 ).

The time interval 984 may be determined according to various strategies. In one example, reflected air pressure pulses 982 may be detected by the control circuitry 109 by analysing the output from the sensor 107 and identifying portions of the output signal where the pressure is greater than a threshold amount. This may, for example, have the effect of filtering out background noise that is picked up by the sensor 107. Peaks may then be identified within the thus-identified portions and, by ascertaining the distance(s) between such peaks (as illustrated in Figure 9), the time interval 984 may be determined.

In a further, more complex example, the control circuitry 109 may apply a correlation function or auto-correlation function to the output from the air pressure wave sensor 107. For instance, where an auto-correlation function is applied, two peaks will typically be apparent in the output signal, the latter of which corresponds to the reflected waves. The interval between the two peaks in the output signal corresponds to time interval 984.

It will be appreciated from Figure 9 that, as well as the sensor 107 detecting the reflected pressure pulses 982, it will typically also detect the presence of the generated pressure pulses 980, shortly after they are generated, as a result of them travelling directly to the sensor, substantially without reflection by the chamber 103.

In order to filter out the pressure oscillations 980 caused by the presence of such direct pressure waves (or otherwise), the control circuitry may be configured such that any output from the sensor 107 is disregarded during a period of time during and/or after generation of the pressure pulses 980. This period of time may have a predetermined length, or may have a length calculated based on various factors, such as the particular drive waveform used, and/or the distance between the sensor 107 and the generating element 105.

On the other hand, it may in some cases be desirable to make use of the output from the sensor 107 that corresponds to the presence of the pressure waves that travel directly to the sensor 107. For instance, such direct pressure waves may be used by the control circuitry 109 for calibration of the device 101 .

In one such example, the control circuitry 109 may use the sensor output corresponding to the direct air pressure waves to update calibration data (which may, for example, be stored on data storage on-board the device 101 ). Such calibration data may then be used by the control circuitry 109 in the later determination of the level of flood-water present within the test chamber 103 (such determination being carried out, for example, in accordance with one of the approaches described above).

Furthermore, such calibration data may, for example, be used to account for variations in temperature and/or humidity (or other factors that may affect the speed of sound within the test chamber 103). For instance, the sensor output corresponding to the direct air pressure waves may be used to directly determine a value for the speed of sound in the test chamber 103, under current conditions.

To determine such a value for the speed of sound, the control circuitry 109 may, in one example, use the sensor output corresponding to the direct air pressure waves to determine a value for the time taken from generation of pressure pulses by the generating element 105 to arrival of the directly-travelling pressure waves at the sensor 107. Using this time value and a known value for the distance between the generating element 105 and the sensor 107, the control circuitry may determine a value for the speed of sound within the test chamber 103, at current conditions.

Such a value for the speed of sound (however determined) may form a part of the calibration data for the device.

In embodiments where the control circuitry 109 applies a drive waveform to the element 105 that comprises one or more drive pulses, the drive waveform may also include one or more damping pulses, which follow the drive pulses. Such damping pulses may act to reduce residual oscillations of the generating element 105 following the application of the drive pulses. To this end, such damping pulses may be substantially in anti-phase to the drive pulses, for instance so as to counteract the effect of the drive pulses on the vibration of the generating element 105.

Alternatively, or in addition, residual oscillations of the generating element may be reduced by short circuiting the generating element 105. Accordingly, the control circuitry may be configured to short circuit the air pressure wave generating element 105 shortly after the series of pressure pulses 980 has been generated. Such short-circuiting may, for example, lead to the vibrational energy of the generating element 105 being dissipated as heat, as a result of resistive (ohmic) heating.

Residual oscillations may likewise cause issues with the sensor(s) 107 of the device. For instance, as discussed above, certain of the generated pressure waves 980 may travel directly to the sensor(s) 107 of the device (e.g. substantially without reflection). Such direct pressure waves will typically be picked up by the sensor(s) 107 prior to the arrival of the reflected pressure waves 982. Moreover, residual oscillations in the sensor(s) 107 resulting from the direct pressure waves may still be present when the reflected waves 982 arrive at the sensor(s) 107. Such residual oscillations may reduce the accuracy with which the sensor(s) 107 can sense the reflected pressure waves 982. Hence (or otherwise), the control circuitry may be configured to short circuit the sensors shortly for a period of time during and/or after the generation of the series reflected air pressure pulses 980. As previously noted, such short-circuiting may, for example, lead to the vibrational energy of the sensors 107 being dissipated as heat, as a result of resistive (ohmic) heating. The period of time may have a predetermined length, or may have a length calculated based on various factors, such as the particular drive waveform used, and/or the distance between the sensor 107 and the generating element 105.

As noted above, Figure 9 illustrates the air pressure in an idealised situation, where, in particular, there is negligible background noise. In practice, there may significant background noise, for example owing to ambient sound or vibration; this holds true for most embodiments, not just that described with reference to Figure 9. Such background noise may make detection of the reflected air waves more difficult and may impact the accuracy of the determination of the level of flood-water present within the chamber 103.

To combat such background noise, the control circuitry 109 may be configured to cause the air pressure wave generating element 105 to generate air pressure waves with increased amplitude in response to identifying excessive background noise in the output from the one or more air pressure wave sensors. A possible consequence of this is that the magnitude of the reflected air pressure waves is increased relative to the magnitude of the background noise picked up by the sensor 107.

The control circuitry 109 may determine the level of background noise using various approaches. In one example, the control circuitry 109 may analyse the output from the sensor 107 during periods when no air pressure waves are being generated by the generating element 106.

As discussed above, in order to differentiate reflected air pressure waves from such background noise, a condition for the control circuitry 109 to determine the presence at the sensor 107 of air pressure waves reflected as a result of flood water within the test chamber may optionally be that the air pressure wave sensor 107 indicates an air pressure wave amplitude greater than a threshold value. (It will however be understood that the control circuitry 109 may be configured such that further conditions must be met in order for it to determine that reflected air pressure waves are present at the sensor 107.) Further, in some embodiments, the control circuitry 109 may be configured to increase this threshold value in response to identifying excessive background noise in the output from the one or more air pressure wave sensors. For example, the threshold might be set at a multiple (e.g. at two or three times) the magnitude of the background noise level.

While the illustrative embodiments described above with reference to Figure 9 involve the operation of the generating element such that it produces a series of pulses, it should be understood that this is by no means essential. For instance, air pressure waves may instead be generated continually. For example, the air pressure wave generating element 105 may continually produce air pressure waves in the test chamber 103 to form a standing wave. Such a standing wave will typically have a particular frequency that depends upon the dimensions of the space within the test chamber 103 that is bounded by the surface of any flood-water present within the chamber 103 and thus on the height of the flood-water level. Thus, by ascertaining this frequency (e.g. by Fourier analysis of the output from the sensor 107), it may be possible for the control circuitry 109 to determine the level of flood-water present within the test chamber 103.

As discussed above, to make this determination, the control circuitry may make use of a value for the speed of sound within the test chamber 103. As also discussed above, this value may be a stored value corresponding to typical operating conditions, a value calculated based on locally measured temperature and/or pressure values (or values for other variables affecting the speed of sound), or a value determined empirically by the device 101 (e.g. as part of a calibration performed by the device 101 ).

In another example, the control circuitry may be configured to drive the wave generating element such that it sweeps through a range of frequencies, generating air pressure waves at various frequencies distributed over that range. The amplitude of the air pressure waves detected by the air pressure wave sensor 107 at each of the various frequencies may be measured and used to determine the resonant frequency for the standing wave within the test chamber. This resonant frequency will typically depend upon the dimensions of the space within the test chamber 103 that is bounded by the surface of any flood-water present within the chamber 103 and thus on the height of the flood-water level. Accordingly, by ascertaining this frequency, the control circuitry 109 may determine the level of flood-water present within the test chamber 103, for instance in a similar manner to that described above.

Attention is now directed to Figures 2, 3A, 3B, 4A and 4B. Figure 2 is a schematic diagram of the device of Figure 1 , where the device is situated in an area that is not experiencing a flood. For example, the device may be attached to the interior wall of a building, and said building may not have any flood water present within it.

In Figure 2 there is no floodwater present in the test chamber 203. Instead the test chamber 203 is empty. Thus, when the air pressure wave generator 205 generates air pressure waves 217, there is no flood water within the test chamber 203 to reflect these. The control circuitry 109 may be configured such that it can recognise such an absence of flood-water within the test chamber 103, from the different way in which generated air pressure waves 217 are reflected.

For example, the control circuitry may detect air pressure waves reflected from the opening 223 of the test chamber 205. Such reflected waves may result from the mismatch of impedances where the test chamber 205 opens to the external environment at the opening 223. Pressure waves reflected by such an open boundary will be of the opposite sense to those reflected by a closed boundary. Furthermore, with an open boundary, pressure waves will often behave as if reflected from a location a short distance beyond the boundary. Thus, a pressure wave reflected by the open boundary at the opening 223 of the chamber may arrive at the sensor 207 somewhat later than a pressure wave reflected by the equivalent closed boundary, where the surface of flood-water obstructs the opening 223. The control circuitry may be configured in such a way as to exploit these phenomena (or others) so as to enable the control circuitry to discriminate such air pressure waves reflected from the opening 223 of the test chamber 205 from those reflected by flood water within the test chamber 205.

Furthermore, where the control circuitry is configured to detect air pressure waves reflected from the opening 223 of the test chamber 205, this may assist in deterring a user from tampering with the device 201 , for example by reducing the space contained within the test chamber 103, 203 through the removal of portions of the device defining a part of the test chamber 103, 203. For instance, where, as in Figures 1 and 2, the test chamber 103, 203 is formed in an elongate member 108, 208, the user might attempt to remove a part of the length of the elongate member 108, 208.

Such attempts to reduce the space contained within the test chamber 103, 203, may affect the location of the opening 223 of the test chamber 205, which is likely to change the nature of the air pressure waves reflected from the opening, e.g. they may arrive earlier at the sensor 207. The control circuitry may accordingly be configured so as to identify such anomalous reflected air pressure waves and, moreover, their identification may be used to trigger a warning condition, which indicates that the device has been or is being tampered with. Deterring a user from tampering with the device may be of particular importance where the device is installed by an insurance service provider and the determined level of flood-water may indicate whether a monetary payment is to be made to the user (though it may of course be of importance in other applications).

In embodiments where the device 101 includes a transmitter, the control circuitry 109 may be configured to cause the transmitter to transmit data relating to the warning condition, for example to the insurance service provider. Such data may, for example, be transmitted substantially immediately after the triggering of the warning condition.

Reference is now directed to Figure 3A and Figure 3B, which are views of the cross sections indicated, respectively, by lines 3A and 3B in Figure 2, and taken through the chamber of the device 101 , 201 of Figures 1 and 2. Each of Figure 3A and Figure 3B shows the inner surface 330 and the outer surface 332 of the elongate member 108, 208.

As is apparent from Figures 1 and 2, and from a comparison of Figures 3A and 3B, over substantially the whole of the length of the test chamber 103, its cross-sectional shape (taken perpendicular to its length) remains substantially the same. Abrupt changes in cross- sectional area may cause the reflection of a portion of the generated air pressure waves; such reflected air pressure waves may be picked up by the sensor 107 and might, in some cases, result in the determination of an anomalous value for the level of flood-water within the test chamber 103. By having a substantially constant cross-sectional shape for the test chamber 103, such effects are reduced. As is also apparent from Figures 3A and 3B, cross- sections of the test chamber perpendicular to its length direction may have a non-circular shape. In the particular example shown in Figures 3A and 3B, the cross sections are oval shaped.

A non-circular cross-sectional shape may, in some cases, be effective at deterring a user from tampering with the device, for example by attempting to reduce the space within the test chamber 103. For instance, where, as in Figures 1 and 2, the test chamber 103, 203 is formed in an elongate member 108, 208, the user might attempt to remove a part of the length of the elongate member 108, 208 and replace it with a portion of a different elongate member (e.g. one having a reduced cross-section). In other cases, the user might attempt to add material (such as a coating or adhesive tape) to the inner surface 330 of the test chamber 103, 203.

In such cases, the user would be unlikely to be able to match exactly the non-circular cross- sectional shape of the original test chamber 103, 203. As a result, the boundary where the altered test chamber meets the unaltered test chamber may cause the reflection of a portion of the generated air pressure waves. Such anomalous reflected air pressure waves may be picked up by the sensor 107 and, where the control circuitry 109 is suitably configured, their identification may be used to trigger a warning condition, which indicates that the device may have been tampered with.

As noted above, in embodiments where the device 101 includes a transmitter, the control circuitry 109 may be configured to cause the transmitter to transmit data relating to the warning condition, for example to the insurance service provided.

Figure 4A and 4B illustrate alternative shapes for the cross sections of the test chamber that are indicated by lines 3A and 3B in Figure 2. The inner surface 430 and outer surface 432 of the elongate member are shown clearly in Figures 4A and 4.

As is apparent, the cross-sections are again non-circular, as they were in Figures 3A and 3B, and thus may likewise be effective at deterring a user from tampering with the device by replacing a portion of the length of the test chamber 103. Furthermore, it is apparent from Figures 4A and 4B that, as in Figures 3A and 3B, the test chamber has substantially the same cross-sectional shape over substantially the whole of its length. Flowever, in contrast to the illustrative embodiment of Figures 3A and 3B, in the embodiment of Figures 4A and 4B the cross-sections are rectangular in shape.

It should be understood that other forms for the test chamber 103 are suitable. In this regard, attention is directed to Figure 5, which is a schematic diagram of a device for sensing the level of flood-water according to a further illustrative embodiment. The device of Figure 5 is generally similar in construction to that of Figures 1 -4, except in terms of the shape of the test chamber 503. Specifically, as may be seen from Figure 5, the test chamber 503 is shaped such that, over substantially the whole its length, its cross-sectional shape (taken perpendicular the length direction) varies smoothly. In the particular example shown in Figure 5, the test chamber tapers smoothly in diameter towards an end at which an opening 523 to the test chamber 503 is located.

As noted above with reference to Figures 2-4, abrupt changes in cross-sectional area may cause the reflection of a portion of the generated air pressure waves; such reflected air pressure waves may be picked up by the sensor 107 and might, in some cases, result in the determination of an anomalous value for the level of flood-water within the test chamber 103. Such effects are not significant in the devices of Figures 1 to 4, since the test chamber has substantially the same cross-sectional shape over substantially the whole of its length. In the device of Figure 5, such effects are addressed by way of the smoothly varying cross- sectional shape for the test chamber 103. As is apparent from a comparison of Figures 6A and 6B, which are views of the cross- sections of the device of Figure 5 indicated by lines 6A and 6B respectively, the cross- sections are geometrically similar, varying only in size. This may simplify manufacture of the device 501 .

Further components may be incorporated in the devices disclosed herein. Specifically, in some embodiments, such as those of Figures 1 to 6, the device may include an air pump, configured to pump air into the test chamber 103, 203, 503 under the control of the control circuitry 109, 209, 509. Specifically, the control circuitry 109 may cause the pump to pump air into the test chamber 103, 203, 503 in such a way (for example, with sufficient pressure and/or flow rate) that substantially all flood-water present within the test chamber is driven out of it, through the opening. The control circuitry 109 may, for example, commence such operation of the pump in response to detecting that flood-water within the test chamber 103. Once the flood-water has been driven out of the test chamber 103 by the pump, the control circuitry 109, 209, 509 may thereafter take one or more readings of the level of flood-water in the test chamber 103, 203, 503.

Such readings may, for example, be taken while flood-water is returning to the test chamber 103, 203, 503 through the opening 123, 223, 523, and/or once the flood-water has reached an equilibrium, or substantially constant level within the test chamber 103, 203, 503. The data from such readings may, in some cases, be used to determine whether the device has been (or is being) tampered with.

For example, it may be expected the height of the flood water within the test chamber 103, 203, 503 will follow a particular trend with respect to time as flood water returns to the test chamber. This expected trend may, for instance, be related to the internal shape of the test chamber and/or the equilibrium level of the flood water. If the trend of the readings with respect to time differs significantly from the expected trend, it may indicate that the test chamber 103, 203, 503 (or the device more generally) has been tampered with and may therefore trigger a warning condition. As discussed above, in embodiments where the device 101 , 201 , 501 includes a transmitter, the control circuitry 109, 209, 509 may be configured to cause the transmitter to transmit data relating to the warning condition, for example to the insurance service provided.

Attention is now directed to Figure 7, which is a schematic diagram of a device for sensing the level of flood-water according to a still further illustrative embodiment, where the device has both a test chamber 703 and a reference chamber 753. The reference chamber 753 may provide additional functionality to the device 701 , for example by assisting in calibrating the device 701 and/or in detecting attempts to tamper with the device 701 . Figure 7 shows the test chamber 703 and the reference chamber 753 in cross-section, so that their interior structures are visible.

As is apparent from Figure 7, the device 701 includes a test chamber 703 of generally similar construction to that illustrated in Figure 1 . Accordingly, the test chamber 703 has an opening 723 through which flood water may enter. In the particular example shown, the opening 723 is located at the bottom of the test chamber 703; however, it may be provided at any suitable location, such as in the side of the test chamber 703. Furthermore, although only one test chamber 703 is shown, there may be any appropriate number of test chambers, e.g. two, three, four, etc.

As is also shown in Figure 7, the device further includes an air pressure wave generating element 705 for the test chamber 703. This element 705 is configured to generate air pressure waves within the test chamber 703. Although only one air pressure wave generating element is shown, several such elements may be used, such as two, three or four air pressure wave generators. As before, the (or each) generating element 705 may, for example, comprise a piezoelectric member to which a drive waveform is applied, causing the piezoelectric member to oscillate and thus produce air pressure waves. Nonetheless, this is merely an illustrative example and any suitable type of generating element 705 may be employed.

As is also visible in Figure 7, the device 701 further includes an air pressure sensor 707. This sensor 707 is configured to detect air pressure waves within the test chamber 703, including those air pressure waves 719 reflected by flood-water within the test chamber 703. Although only one sensor 707 is shown, any suitable number of sensors may be employed for detecting air pressure waves in the test chamber 703.

Turning now to the reference chamber 753, in contrast to the test chamber 703 this is sealed (in the illustrated example, by seal 771 ) so as to substantially prevent the entry of flood water.

As is also apparent from Figure 7, the device 701 according to the particular embodiment shown includes an air pressure wave generating element 755 for the reference chamber 753. As illustrated, this air pressure wave generating element 755 is configured to generate air pressure waves 767 within the reference chamber 753, which are then reflected by the reference chamber 753, in particular by its interior surfaces (including, in the illustrated example, those of the seal 771 ). Although only one air pressure wave generating element 755 is shown it should be appreciated that any number of generating elements may be provided for the reference chamber 753. Indeed, in some embodiments the test chamber 703 and the reference chamber 753 could share one or more air pressure wave generating elements.

As also shown in Figure 7, the device 701 further includes an air pressure wave sensor 757. This is configured to detect air pressure waves 769 that have been reflected by the interior surfaces of the reference chamber 753, having previously been generated by an air pressure wave generating element (for instance, in the illustrated example, by the dedicated air pressure generating element 755 for the reference chamber 753).

Although one air pressure wave sensor 757 for the reference chamber 753 is shown, it should be appreciated that any number of sensors may be provided for the reference chamber 753. Indeed, rather than there being respective air pressure wave sensors for the test chamber 703 and reference chamber 753, in some embodiments the test chamber 703 and the reference chamber 753 may share one or more air pressure wave sensors.

As further shown in Figure 7, the device includes control circuitry 709, which is configured to cause the air pressure wave generating elements 705, 755 to generate air pressure waves 717, 767 within the test chamber 703 and the reference chamber 753 and, based on the resulting output from the air pressure wave sensors 707, 757, including the output corresponding to the air pressure waves reflected by the interior surfaces of the reference chamber 753, to determine the level of flood water present within the test chamber.

The reference chamber 753 may be viewed as acting as a control (or reference) to be compared with the test chamber 703. For instance, the way in which air pressure waves are reflected within the reference chamber 753 (and the resulting sensor output) may be compared with that for the test chamber 703. As noted above, the reference chamber 753, in contrast to the test chamber 703, is sealed, so as to substantially prevent the entry of flood water. Thus, the differences between the chambers 703, 753 in how generated waves are reflected may be expected to result, at least in part, from the presence of flood-water within the test chamber 703.

In some embodiments, the control circuitry may be configured to carry out a calibration using the reference chamber 753.

For example, as part of such a calibration, the control circuitry 709 may cause the air pressure wave generating element 755 to generate air pressure waves 767 within the reference chamber 753, which are then reflected by the interior surfaces of the at least one reference chamber 753. The control circuitry may then update calibration data, based on the output from the air pressure wave sensors 757 that corresponds to the air pressure waves 769 reflected by the interior surfaces of the reference chamber 753. This calibration data may then be used by the control circuitry in later determinations of the level of flood water present within the test chamber 703 (such determinations being carried out, for example, in accordance with one of the approaches described above). Accordingly, such calibration data may, for example, be stored on data storage on-board the device 701.

Such calibration data may, for example, be used to account for variations in temperature and/or humidity, or other factors that may affect the speed of sound within the test chamber 103. For instance, the sensor output from the air pressure wave sensors 757 that corresponds to the air pressure waves 769 reflected by the interior surfaces of the reference chamber 753 may be used to directly determine a value for the speed of sound in the reference chamber 103, under current conditions. (In many cases, it may be assumed that the speed of sound is the same in both the reference and test chambers, to a reasonable level of approximation.)

The control circuitry may be configured to determine such a value for the speed of sound using one (or more) of a variety of approaches. In one example, the control circuitry 709 may, analyse the time taken from generation of air pressure pulses by the generating element 755 to arrival at the sensor 757 of the corresponding air pressure pulses reflected by the interior surfaces of the reference chamber 753. In another example, the generating element 755 might continuously generate air pressure waves so as to produce a standing wave within the reference chamber 753. The control circuitry 709 may then identify a characteristic frequency of the standing wave to determine the speed of sound within the reference chamber 753 (as the characteristic frequency will typically depend in a predictable fashion on the speed of sound). Indeed, it should be noted that, where the reference chamber 753 is provided with its own generating element(s) 755, these may (as part of the calibration or otherwise) be operated according to a different approach to the generating element(s) 705 of the test chamber 703.

The value for the speed of sound - however determined - may form a part of the calibration data for the device.

In embodiments, such as that of Figure 7, where dedicated sensors 707, 757 are provided for each of the test chamber 703 and the reference chamber 703 (i.e. sensors are not shared between the chambers), the control circuitry 709 may be configured to determine the level of flood water present within the test chamber 703 by comparing the output from the sensor(s) 707 corresponding to the test chamber 703 with the output from the sensor(s) 757 corresponding to the reference chamber 753. For example, the control circuitry 709 might determine the difference between the output from the test chamber sensor(s) 707 and that from the reference chamber sensor(s) 757 (e.g. by using a differential amplifier). Such a subtraction operation may act to filter out background noise from the sensor outputs, since in many cases such background noise may be expected to be picked up equally by the sensors for both chambers.

It should be noted that embodiments with reference chambers 753, such as the illustrative embodiment shown in Figure 7, may be configured to operate in a similar manner to that described above with reference to Figure 9. Accordingly, the control circuitry 709 may be further configured to cause the pressure wave generating elements 705 and 755 to generate a series of one or more pressure pulses (e.g. as are shown in Figure 9) and to determine the level of flood water present within the test chamber 703 based on the respective time intervals for the test chamber 703 and the reference chamber 753 from the generation by the generating elements 705, 755 of the one or more pressure pulses to the detection of the corresponding reflected air pressure waves by the air pressure wave sensors 707, 757.

Typically, these time intervals will be different, as the time interval for the test chamber 703 will vary depending on the current level of flood-water therein, whereas the time interval for the reference chamber 753 may, for example, vary depending on the current atmospheric conditions only. Therefore, the time interval value for the reference chamber 753 may, for example, be used by the control circuitry 709 to account for/correct for variations in temperature and/or humidity (or other factors that may affect the speed of sound within the chambers 703, 753), so as to further improve the accuracy of the determination of the level of flood-water within the test chamber 703.

In terms of its form, the reference chamber 753 may have generally the same shape as the test chamber 703, as shown in Figure 7. This may, for example, simplify the comparison between the reference chamber 753 and the test chamber 703 in terms of how generated waves are reflected. Furthermore, in embodiments such as that shown in Figure 7 where the test chamber 703 is elongate, the reference chamber 753 may also be elongate and may, for example, have the same length as the test chamber 703, as also shown in Figure 7. Additionally, or alternatively, the test chamber 703 and reference chamber 753 may be described as being arranged side-by-side.

Flowever, it should be understood that it is not essential for the reference chamber 753 to have generally the same shape as the test chamber 703. In one example, the test chamber 703 and the reference chamber 753 could have similar shapes, but different sizes, for instance in a known ratio to one another, e.g. where both are elongate chambers, the reference chamber 753 could be a known fraction of the length of the test chamber 703, such as half its length.

In another example, the reference chamber 753 and the test chamber 703 may have complementary cross-sectional shapes (e.g., such that they fit together). For example, one of them may have a substantially male cross sectional shape, and the other may have a substantially female cross sectional shape. This may, in some cases, be effective at deterring a user from tampering with the device, for example by attempting to reduce the space within the test chamber 703. Were such a modification attempted, it is unlikely that the user would succeed in exactly matching such complex cross-sectional shapes. The boundary where the altered test chamber meets the unaltered test chamber may as a result cause the reflection of a portion of the generated air pressure waves. Such reflected air pressure waves may be picked up by the sensors 707, 757 and, where the control circuitry 709 is suitably configured, their identification could be used to trigger a warning condition, which indicates that the device may have been tampered with.

In embodiments such as that shown in Figure 7, where both the test chamber 703 and reference chamber 753 are elongate, the air pressure wave generating elements 705, 755 and the air pressure wave sensors 707, 757 may both be provided at respective first longitudinal ends of the test chamber 703 and reference chamber 753 (in the illustrated example, the top ends of the test chamber 703 and reference chamber 753). In such embodiments, a second, opposing longitudinal end of the reference chamber 753 (in the illustrated example, the end where seal 771 is located) may cause the reflection of at least the majority of the air pressure waves 767 generated within the reference chamber 753. A possible consequence is that such air pressure waves reflected by the second longitudinal end of the reference chamber 753 correspond to an easily-identifiable peak in the output from the air pressure sensor 757 for the reference chamber 753.

As a further structural feature, in some embodiments, both the reference and test chambers 753, 703 may have an opening or passageway (not shown) connecting the chambers such that air can travel between them. The same or an additional opening or passageway may enable air to travel from the chambers to the exterior, so that, for example, the air within the chambers is at generally the same temperature and pressure as the surrounding environment.

It will be noted that, in the illustrative embodiment of Figure 7 the test chamber 703 and the reference chamber 753 are shown as being provided within respective elongate members 708, 758; however, this is not essential and, instead, both may conveniently be provided within a single elongate member. This is demonstrated by the illustrative embodiment of Figures 8A and 8B, which is generally similar to the device of Figure 7, except in that both a test chamber 803 and a reference chamber 853 are provided within the elongate member 808 illustrated.

Figure 8A and Figure 8B are, respectively, a front view and a side view of the device 801 , when installed on a wall or other vertical surface (the vertical direction being indicated by arrow V). As is apparent, the device 801 shown includes a housing 81 1 , as well as an elongate member 808. As described above, this housing 81 1 may contain control circuitry, the air pressure wave generating element(s) and air pressure wave sensor(s), for example sealing the control circuitry in a water-resistant manner. Flowever, as noted above, such a housing is by no means essential.

In one embodiment the device is mounted to the interior wall of a building. This building may be a residential building, an office building, a shop, warehouse, car park, prison, factory, hospital, school or other commercial or public property.

Mounting the device to the interior wall of a building means allows the flood water level within the building to be determined from the level of water measured in the chamber. For example, this may depend on the position of the device within the building, and in some cases the level of water within the chamber may correspond to the flood level within the building.

The flood level within the building may be an important parameter, as it verifies if the interior of a building has been flooded by the flood water, and the level of said flood water. The level of flood water may be indicative of the amount of damage that may be caused to the building by the flood. This information could also be used by the emergency services if required.

It is also noted that several devices may be employed within a single premises. This array of devices may then measure the extent of the flooding. For example, a large building such as a hospital may have a large floor footprint, and therefore not all of the footprint may flood at the same time. An array of devices may allow the footprint of the building to be characterised so that it is known which areas of the building have flooded without carrying out a detailed survey. This information may also be captured in real time as the flood water level is rising which may have a number of uses, including increasing public safety, and planning for future flood events.

Configuring the device such that it can be mounted to the wall of a building (e.g. using elongate fasteners, such as screws) may enable it to be robustly fixed in a desired location and orientation (e.g. with respect to the vertical direction V). Figures 10-14 show a device 1001 for sensing the level of flood-water according to a further illustrative embodiment, where the device includes various features that assist its mounting to the wall of a building.

Figures 10 is an exploded perspective view of the device 1001 , and shows clearly the various components of the device, whereas Figure 1 1 is a partially exploded view and Figure 12 is a perspective view of the assembled device, illustrating how the device is assembled. Figures 13 and 14 are, respectively, a front view and a side profile view of the assembled device.

As is apparent from the respective views, the device of Figures 10-14 is configured such that it can be mounted to a wall by embedding a number of elongate fasteners 1046, for example screws, into the wall, with such fasteners then attaching the device to the wall. More particularly, as will be appreciated from a comparison of Figure 10 with Figure 12, the fasteners attach the device to the wall in such a way that portions of the fasteners not embedded within the wall (e.g. the screw heads) are substantially covered by the device. In this way, the fasteners 1046 are made inaccessible to a user. A possible consequence is that it is difficult for the user to remove the device 1001 from the wall, at least not without making it evident that it has been tampered with. Additionally, it may be difficult for a thief or vandal to remove the device from the wall.

It should be noted in this regard that, in many cases, for the measurements of flood-water level taken by the device to be meaningful, the device will need to remain fixed in its installed position. For example, if a device were moved to a lower vertical position, readings taken from it thereafter might incorrectly imply a higher level of flood-water, than if it had remained in its original position. Furthermore, a user might attempt to move the device so as to place it in a wet environment, such as a bath or bucket of water, thus tricking the device into sensing a flooding event.

Potentially, it may be possible to address such issues by providing the device with a positioning system (e.g. comprising an inertial measurement unit or a satellite navigation system receiving unit), enabling the device to detect any changes in its position; however, this would significantly increase the complexity and/or cost of the system. Hence, efforts are taken in the device of Figures 10-14 to prevent the device being removed from a wall, once fixed in place.

Specifically, referring once more to Figure 10, it may be noted that the particular example of a device 1001 shown includes control circuitry 1009, a test chamber 1003, a reference chamber 1053, and an elongate member 1008. As with the embodiment of Figure 8, both the test chamber 1003 and the reference chamber 1053 are provided within this elongate member 1008; however, this is not essential and the reference chamber 1053 could be omitted in other embodiments.

As may also be seen from Figures 10-14, in the particular example embodiment shown, the device 1001 includes a housing 101 1 that contains the control circuitry 1009, the air pressure wave generating element and the air pressure wave sensor. In the specific example shown in the drawings, the housing 101 1 comprises two parts 101 1 A, 101 1 B, which are joined together to seal the control circuitry 1009 in a water-resistant manner, for example so as to protect it from damage by flood water.

Furthermore, in the particular example shown, a grating 1040 is disposed on the exterior of the housing 101 1 (specifically, on the outward-facing of the two parts 101 1 A, 101 1 B of the housing).

As is also apparent from Figures 10-14, one longitudinal end of the elongate member 1008 is received within the housing 101 1.

A further feature of the device 1001 is apparent from a comparison of Figure 10 with Figures 1 1 and 12. Specifically, it is apparent that, when the device 1001 is mounted to a wall, the elongate member 1008 will cover some of the fasteners 1046 (and, specifically, the portions of them not embedded with the wall - here, their ends), thus causing these fasteners 1046 to be inaccessible to a user. A possible consequence is that it is difficult for the user to remove the device 1001 from the wall (or at least not without making it evident that it has been tampered with).

Moreover, in some embodiments, tampering may be detected by the control circuitry using the output from the air pressure wave sensors of the device. To give one example, attempts to access the fasteners 1046 behind the elongate member 1008 will generate noise and/or vibration, which may be picked up by the air pressure wave sensor(s). To give another example, where the elongate member 1008 is interfered with, for instance by cutting into it to access the fasteners, this may alter the shape of the test chamber 1003 and/or the reference chamber 1053 (where present), thus altering the way in which they reflect air pressure waves, which again may be detected by the air pressure wave sensor(s). Where the control circuitry determines, based on the output from the air pressure wave sensor(s), that such tampering has occurred, it may then trigger a warning condition. As noted above, in embodiments where the device 1001 includes a transmitter, the control circuitry 1009 may be configured to cause the transmitter to transmit data relating to the warning condition, for example to the insurance service provider. In addition, the control circuitry 1009 may, as described above, be configured to identify the presence of anomalous air pressure waves (for example, anomalous reflected pressure waves, such as those caused by the presence of an object within the test chamber, or those resulting from the change in position of the opening of the test chamber as a result of a portion of the test chamber being removed) using the output from the air pressure wave sensor(s), and to then trigger a warning condition in response.

Returning now to Figures 10-14, it may be noted that, in the particular illustrative embodiment shown, the device 1001 includes a number of fastener-receiving portions 1051 and a number of cover members 1050. Further, as is apparent from a comparison of Figure 10 with Figures 1 1 and 12, these cover members 1050 are connectable to corresponding connecting portions 1048 of the device, which are adjacent the fastener-receiving portions 1051 . The cover members 1050, once connected to the connecting portions 1048, cover certain of the fasteners 1046, rendering them inaccessible to a user.

It may be noted that in the particular example shown, certain of the fasteners 1046 are thus covered by both a cover member 1050 and the elongate member 1008. Flowever, this is of course not essential and in other embodiments certain of (or all of) the fasteners 1046 may be covered solely by a cover member 1050, whereas certain of (or all of) the fasteners 1046 may be covered solely by the elongate member 1008.

In general, the connection formed between the cover members 1050 and the connecting portions 1048 may be such that it cannot be disengaged without breaking or cutting part of the device. In some embodiments, the connection may be a non-return mechanical connection, such as a snap-fit non-return connection, or a different type of non-return mechanical connection, for example, one utilising locking teeth that are angled so as to resist decoupling.

As is shown in Figure 10, the device may further include a number of brackets 1044, with the connecting portions 1048 being provided on these brackets 1044. As is apparent from the respective shapes of the cover members 1050 and brackets 1044, each bracket 1044 connects with a cover member in such a way as to encircle or surround the elongate member 1008 therebetween. This may further obstruct attempts to access the fasteners 1046, for example in an effort to move the device 1001.

While in the particular example shown in the drawing the fastener-receiving portions 1051 are mounting apertures, through which the fasteners 1046 are inserted, it will be understood that this is not essential and that these portions can be any shape suitable for receiving a fastener, for example a notch, slot, U-shaped portion, or the like. Various optional features to deter tampering attempts may be incorporated in any of the devices described above with reference to Figures 1 -14.

In one such further optional feature, the control circuitry 109, 209, 509, 709, 1009 may be configured to determine whether the determined level of flood water is changing with respect to time at an anomalous rate, for example a rate greater than a threshold amount, and to trigger such a warning condition in response. Such a threshold amount might, for instance, represent an upper bound for naturally-occurring rises in water level; thus, rises in excess of this threshold may indicate an attempt to tamper with the device, for example by inserting an object into the test chamber 103, 203, 503, 703, 1003.

In a further optional feature to deter tampering, the control circuitry 109, 209, 509, 709, 1009 may be configured so as to take readings at a pseudo-random frequency. Where readings are taken at a regular frequency, it is considered possible that a user might attempt to determine this frequency, for example by attempting to detect the air pressure waves generated by the generating element(s) 105, 205, 505, 705, 1005 of the device (e.g. by using a sensing device, or, where the air pressure waves are sound waves, by listening to the device). Having determined this frequency, the user might attempt to tamper with the device between readings, so as to avoid such tampering being detected. However, by taking readings at a pseudo-random frequency, a user is deterred from adopting such a strategy, since they cannot anticipate when the next reading will be taken.

In a still further optional feature, the device 101 , 201 , 501 , 701 , 801 , 1001 may additionally include a camera, which is configured to capture images of the surroundings of the device. The control circuitry may be configured to cause the camera to capture such an image of the surrounding environment in response to a warning condition being triggered (e.g. according to one of the protocols described above). In such embodiments, the device may be considered to include a security camera, thus deterring attempts to tamper with the device. To assist such image capture, the device may further include a light source (for instance including one or more LEDs), which is coupled to the control circuitry 109, 209, 509, 709, 1009, so that the control circuitry can cause the light source to illuminate the surroundings of the device when the camera to captures an image.

It should be appreciated that various modifications may be made to the embodiments described above with reference to Figures 1 -14, for instance by combining features that have been presented with reference to different embodiments.

For example, it should be noted that a pump as described above (one that is configured to pump air into the test chamber(s) of the device and to thereby drive substantially all flood- water out of the test chamber) may be incorporated in a device according to any of the embodiments described herein, with the control circuitry being configured in a suitable manner, as also described above.

It should additionally be noted that, although Figures 1 -14 show generating elements and sensors as being separate components, as discussed above with reference to Figure 1 , these may share various common components, or, indeed, a single component may act as both a generating element and sensor. For example, a generating element and a sensor might share a piezoelectric member or voice coil that is used to both generate (transmit) air pressure waves and to sense the presence of (receive) air pressure waves.

It should further be noted that the dimensions for the test chamber 103 set forth above with reference to the embodiment of Figure 1 may be suitable for the test chamber of any of the devices described above with reference to Figures 1 -14 and, moreover, may be suitable for the reference chamber in such devices.

Furthermore, it should be noted that any of the features described above with reference to the device of Figures 10-14 that assist in mounting the device on a wall may equally be incorporated in any of the devices described above with reference to Figures 1 -9. Likewise, Furthermore, it should be noted that any of the features described above with reference to the device of Figures 10-14 that assist in deterring a user from tampering with the device may be incorporated in any of the devices described above with reference to Figures 1 -9.

Methods for sensing the level of flood-water

The present disclosure also provides methods for sensing the level of flood-water.

In this regard, reference is now directed to Figure 15, which is a flow-diagram illustrating a method of sensing the level of flood water according to an illustrative embodiment of the present disclosure. As is apparent from Figure 15, the method comprises steps 1510-1540.

In more detail, Figure 15 illustrates step 1510 of providing a device comprising at least one test chamber, which has an opening through which flood water may enter. This device may be provided such that it is attachable to the interior wall of a building, and in some cases, such that it is attached to the interior wall of a building.

Figure 15 illustrates step 1520 of generating air pressure waves within the at least one test chamber, flood water that has entered the at least one the test chamber causing the reflection of at least some of the generated air pressure waves. Figure 15 further illustrates step 1530 of detecting air pressure waves present within the test chamber, including said air pressure waves reflected as a result of flood water that has entered the at least one test chamber.

Figure 15 further illustrates step 1540 of determining the level of flood water present within the at least one test chamber based on the detected reflected air pressure waves. This may then be used to determine the level of flood water within the interior of the building.

In some embodiments, the method may further include transmitting data relating to the level of flood water, as determined in step 1540. This transmittal may be to a third party, such as to a server storing a database containing data on a plurality of flood detecting devices, so as to monitor several areas at once.

It should further be noted that, as part of step 1510, the device provided may be any of the devices described herein, such as those described above with reference to Figures 1 -14. Furthermore, any operational features of the devices described above with reference to Figures 1 -14 may be implemented in the method of Figure 15 as corresponding process features.

It should be noted that in one embodiment after the installation of the device to mount the device to a wall of the building the fixed elevation data of the device (the height of the device relative to the ground) may be measured. This value may be noted down, and the device given an identification number.

When transmitting the data relating to the level of the flood water, the device may send the identification number in the same transmittal pack, such that the data can be identified as belonging to the device that recorded the data. Moreover, the device may also send the fixed elevation data of the device in the transmittal pack. In an alternative embodiment this fixed elevation data may already be input into the database of the flood devices. The fixed elevation data may be used in conjunction with the flood level data to determine the extent of the flooding at each device. It is also noted that the server may contain a data store containing the identification number, such that the identification number can be cross referenced against the data store.

Methods for installing a device for sensing the level of flood-water

The present disclosure also provides methods for installing a device for sensing the level of flood-water. In this regard, reference is directed to Figure 16, which is a flow-diagram illustrating a method for installing a device for sensing the level of flood-water according to an illustrative embodiment. As is apparent from Figure 16, the method comprises steps 1610-1630.

More particularly, Figure 16 illustrates step 1610 of providing a device for sensing the level of flood-water, such as those described above with reference to Figures 1 -14 as described above with reference to Figures 1 -14.

Figure 16 further illustrates step 1620 of fixing the device at a chosen site, thus resulting in the device having a fixed elevation. The device may be fixed to the interior wall of a building, such that the level of flood water within the building may be measured by the device.

Figure 16 further illustrates step 1630 of storing data relating to said fixed elevation.

With regard to step 1610, in order to provide a device having an elongate test chamber disposed within an elongate member (for example as described above with reference to Figures 1 -14 above), the method may optionally include providing an elongate hollow component having a longitudinally extending lumen, and removing a portion of the length of that elongate hollow component. The remaining portion of the elongate hollow component then provides the elongate member of the device and the elongate test chamber of the device is provided, at least in part, by the remaining portion of the longitudinally extending lumen. This may allow for the provision of a device with an elongate member of suitable size for a specific location.

In order to provide a device that includes both an elongate test chamber and an elongate reference chamber (for example as described above with reference to Figure 8 or Figures 10-14), the elongate hollow component may accordingly include a first and a second longitudinally extending lumen. Following removal of the portion of the length of the elongate hollow component, the remaining portion of the elongate hollow component will (as before) provide the elongate member in the installed device; the remaining portion of the first longitudinally extending lumen will provide the elongate test chamber in the installed device. To provide the reference chamber (which is sealed so as to substantially prevent the entry of flood water), the method may include blocking one longitudinal end of the remaining portion of the second lumen, with the thus-blocked second lumen providing the reference chamber of the installed device.

Blocking the longitudinal end of the lumen may, for example, include attaching a blocking element to the longitudinal end. In some embodiments, the blocking element may be a plug that is inserted into the end, or a cap that is attached to the end. It should however be understood that, in order to provide a device having an elongate test chamber disposed within an elongate member, it is by no means essential for step 1610 to include providing an elongate hollow component having a longitudinally extending lumen, and removing a portion of the length of that elongate hollow component. As an alternative (or in addition), step 1610 may include selecting an elongate member from an inventory of differently-sized elongate members. During installation, the environment in which the device is being installed may not be a suitable size for the device; a suitably-sized elongate member may therefore be selected according to the particular environment where the device is being installed.

In order for the device to be calibrated for the specific length of the elongate member provided (whether it is provided by removal of a portion from an elongate hollow component, or by selection from an inventory of elongate members, or otherwise), adjustment data determined based on the specific length may, in some embodiments, be provided to the control circuitry. Such adjustment data may then be used by the control circuitry in the determination of the level of flood water present within the test chamber.

In some embodiments, providing the adjustment data may include entering data relating to the length of the elongate member into a handheld device, such as a smart-phone, tablet computing device, or PDA. For instance, this might simply involve entering a measured value for the length of the elongate member into an application running on the handheld device.

The handheld device then generates the adjustment data using the thus-entered length data and causes the transmission of the adjustment data to the control circuitry, whether by transmitting the adjustment data directly to the control circuitry, or otherwise. The handheld device might instead (or in addition) upload the adjustment data to the cloud and/or to a server, so that, for example, when future transmissions regarding flooding data are uploaded by the device, the adjustment data may be used to interpret the newly received data.

It should further be understood that the device installed in step 1610 may include any of the features described above with reference to the devices of Figures 1 -14.

Turning now to step 1620, fixing the device at a chosen site may comprise mounting the device on a wall at the chosen site. The general area for the site will usually be determined based on where it is desired to measure the level of flood water. However, the specific site within that general area may be selected such that, for instance, the portion of the wall where the device is to be mounted is free from bumps, and/or is within a certain height range and/or is distant from a heat source, or sound source. Furthermore, mounting the device to a wall may comprise embedding elongate fasteners (such as screws) into the wall, with the device being attached to the wall by the one or more fasteners in such a way that the fasteners are substantially covered by the device with the fasteners thus being inaccessible to a user. The device may accordingly include any of the features described above with reference to Figures 10-14 that assist in the mounting of the device shown therein.

With regard to step 1630, the data relating to the fixed elevation might include the height of the device above the local ground level (for example measured from ground level to a reference point on the device) or it could include the height above sea level, or the elevation relative to a reference geoid.

Furthermore, it should be noted that, in some embodiments, the data relating to the fixed elevation may be stored remotely of the device (though it could instead be stored on-board the device). For example, the data may be stored in the cloud and/or stored on one or more servers. Such fixed elevation data may then be used to interpret data generated by the device during use, so that, for example, data indicating a height of flood-water within the test chamber of the device may be used to determine a value for the height of flood-water relative to local ground level, sea level etc. The fixed elevation data may be stored in the control circuitry and sent to a server in a transmittal pack, or alternatively may be stored in the server to negate the need for repeat sending.

Purpose and scope of the disclosure

It will of course be appreciated that the illustrative embodiments presented above are only examples. It should in particular be noted that combinations of the above examples are envisaged.

More generally, it should be appreciated that other examples and variations are contemplated within the scope of the appended claims.

It should be noted that the foregoing description is intended to provide a number of non limiting examples that assist the skilled reader’s understanding of the present invention and that demonstrate how the present invention may be implemented.

Please see the below numbered clauses setting out features of the above disclosure:

1. A device for sensing the level of flood-water, comprising:

at least one test chamber having an opening through which flood water may enter; one or more air pressure wave generating elements, configured to generate air pressure waves within said at least one test chamber;

one or more air pressure wave sensors, configured to detect air pressure waves present within the at least one test chamber; and

control circuitry, coupled to said one or more air pressure wave generating elements, said one or more air pressure wave sensors, and configured:

to cause said one or more air pressure wave generating elements to generate air pressure waves within the at least one test chamber, at least some of which are reflected by flood water that has entered the test chamber; and

to determine the level of such flood water present within the test chamber, based on the resulting output from said one or more air pressure wave sensors, including the output corresponding to said air pressure waves reflected as a result of the flood water.

2. A device according to clause 1 , further comprising a transmitter coupled to said control circuitry and configured to transmit data; wherein said control circuitry is further configured to cause said transmitter to transmit data relating to the thus-determined level of flood water.

3. A device according to clause 1 or clause 2, wherein the at least one test chamber is elongate.

4. A device according to clause 3, wherein the length of the test chamber is between about 0.5m and 5m.

5. A device according to clause 3 or clause 4, wherein the width of the test chamber is between about 3mm and 25mm,

6. A device according to any one of clauses 3 to 5, wherein the length of the test chamber is at least 20 times greater, preferably at least 100 times greater, and more preferably at least 1000 times greater than its width.

7. A device according to any one of clauses 3 to 6, wherein said one or more air pressure wave generating elements and said one or more air pressure wave sensors are located at or adjacent a first longitudinal end of the at least one test chamber.

8. A device according to clause 7, wherein said opening is located at or adjacent a second, opposing longitudinal end of the at least one test chamber.

9. A device according to clause 8, wherein the device is configured for operation with the first longitudinal end of the at least one test chamber vertically above the second longitudinal end. 10. A device according to anyone of clauses 7-9, wherein the device is configured for operation with the first longitudinal end of the at least one test chamber vertically above said opening in the chamber.

1 1 . A device according to any one of clauses 3 to 10, wherein, over substantially the whole of the length of the chamber, the cross-sectional shape of the at least one test chamber perpendicular the length direction, remains substantially the same.

12. A device according to any of clauses 3 to 10, wherein, over substantially the whole of the length of the chamber, the cross-sectional shape of the at least one test chamber perpendicular the length direction varies smoothly.

13. A device according Clause 1 1 or Clause 12, wherein, over substantially the whole of the length of the chamber, the cross-section perpendicular the length direction has a non circular shape.

14. A device according to any one of clauses 3 to 13, further comprising an elongate member, the at least one test chamber being provided at least in part, and preferably substantially, within said elongate member.

15. A device according to clause 14, wherein the opening(s) for the at least one test chamber extend through said elongate member.

16. A device according to clause 14 or clause 15, when dependent upon clause 2, wherein the length of the elongate member extends parallel to the length of each of the at least one test chamber.

17. A device according to any one of clauses 14 to 16, wherein said elongate member is integrally-formed.

18. A device according to any one of clauses 14 to 17, wherein at least the structure of the elongate member is formed of polymeric material.

19. A device according to one of clauses 14 or 17, wherein said elongate member comprises a series of markings on its exterior surface that provide a distance or volume scale for the at least one test chamber.

20. A device according to any of clauses 14 to 19, wherein the device is configured to be mounted with said elongate member angularly spaced from the horizontal, and preferably arranged substantially vertically. 21 . A device according to any preceding clause, further comprising at least one reference chamber which is sealed so as to substantially prevent the entry of flood water;

wherein said one or more air pressure wave generating elements are further configured to generate air pressure waves within said at least one reference chamber that are then reflected by the interior surfaces of the at least one reference chamber;

wherein said one or more air pressure wave sensors are configured to detect air pressure waves present within the at least one reference chamber;

wherein the control circuitry is configured to cause said one or more air pressure wave generating elements to generate air pressure waves within the at least one test chamber and the at least one reference chamber and, based on the resulting output from said one or more air pressure wave sensors, including the output corresponding to said air pressure waves reflected by the at least one reference chamber, to determine the level of flood water present within the at least one test chamber.

22. A device according to clause 21 , when dependent upon clause 3, wherein the at least one reference chamber is elongate.

23. A device according to clause 22, when dependent upon clause 7, wherein said one or more air pressure wave generating elements and said one or more air pressure wave sensors are located at or adjacent a first longitudinal end of the at least one reference chamber;

preferably wherein at least the majority of the air pressure waves generated within the at least one reference chamber are reflected by a second, opposing longitudinal end of the at least one reference chamber.

24. A device according to any one of clauses clause 21 to 23, wherein the at least one reference chamber has generally the same shape as the at least one test chamber.

25. A device according to any one of clauses 21 to 24, wherein the at least one test chamber and the at least one reference chamber have complementary cross-sectional shapes.

26. A device according to any one of clauses 21 to 25, wherein the length of each of the at least one reference chamber is parallel to the length of each of the at least one test chamber.

27. A device according to any of clauses 21 to 26, wherein the at least one test chamber and the at least one reference chamber are arranged side-by-side. 28. A device according to clause 14 and any of clauses 21 to 27, wherein the at least one test chamber and the at least one reference chamber are provided within the elongate member.

29. A device according to any one of clauses 21 to 28, wherein the control circuitry is configured to carry out a calibration, in which the control circuitry:

causes said one or more air pressure wave generating elements to generate air pressure waves within said at least one reference chamber that are then reflected by the interior surfaces of the at least one reference chamber; and

in accordance with the output from the one or more air pressure wave sensors

corresponding to the air pressure waves reflected by the interior surfaces of the at least one reference chamber, updates calibration data;

wherein said calibration data is used by the control circuitry in said determination of the level of flood water present within the at least one test chamber.

30. A device according to clause 29, wherein said calibration data is used to account for variations in temperature and/or humidity.

31 . A device according to any of clauses 21 to 28, wherein the one or more air pressure wave sensors comprise a group of one or more air pressure wave sensors for the at least one test chamber and a group of one or more air pressure wave sensors for the at least one reference chamber;

wherein the control circuitry is configured to determine the level of flood water present within the test chamber by comparing the output from the group of sensors corresponding to the at least one test chamber with the output from the group of sensors corresponding to the at least one reference chamber.

32. A device according to clause 31 , wherein comparing the output from the group of sensors corresponding to the at least one test chamber with the output from the group of sensors corresponding to the at least one reference chamber comprises determining the difference between the respective outputs from the groups of sensors.

33. A device according to any of clauses 21 -32, wherein said one or more air pressure wave generating elements comprise a group of one or more air pressure wave generating elements for the at least one test chamber and a group of one or more air pressure wave generating elements for the at least one reference chamber. 34. A device according to any preceding clause, further comprising a housing, within which said control circuitry, said one or more air pressure wave generating element and said one or more air pressure wave sensor are provided.

35. A device according to clause 34, wherein said control circuitry is sealed within the housing in a water-resistant manner.

36. A device according to one of clauses 34 or 35, when dependent upon Clause 14, wherein a longitudinal end of said elongate member is received within said housing.

37. A device according to any preceding clause, wherein the control circuitry is further configured to cause the one or more air pressure wave generating elements to generate a series of one or more pressure pulses and to determine the level of flood water present within the at least one test chamber based on the time interval from the generation by the one or more generating elements to the detection of the corresponding reflected air pressure waves by the one or more air pressure wave sensors.

38. A device according to any preceding clause, wherein the control circuitry is configured to cause each of the one or more air pressure wave generating elements to operate at its resonant frequency.

39. A device according to any preceding clause, wherein the air pressure waves generated by the one or more air pressure wave generating elements have a frequency of between 50Hz and 20 KHz, preferably between 2 KHz and 8 KHz.

40. A device according to any preceding clause, wherein the control circuitry is configured to apply a drive waveform to each of said one or more air pressure wave generating elements that comprises one or more drive pulses.

41 . A device according to Clause 40, wherein the drive waveform further comprises one or more damping pulses, which follow said drive pulses and are substantially in anti-phase thereto.

42. A device according to any preceding clause, when dependent upon Clause 37, wherein the control circuitry is configured to short circuit the one or more air pressure wave generating elements shortly after said series of one or more pressure pulses has been generated.

43. A device according to any preceding clause, when dependent upon Clause 37, wherein the control circuitry is configured to short circuit the one or more air pressure wave sensors for a period of time during and/or after the generation of said series of one or more pressure pulses.

44. A device according to any preceding clause, when dependent upon Clause 37, wherein the control circuitry is configured such that any output from said one or more air pressure wave sensors is disregarded during a period of time during and/or after generation of said series of one or more pressure pulses, said period of time preferably having a predetermined length.

45. A device according to Clause 44, wherein said one or more air pressure wave sensors are deactivated during said period of time.

46. A device according to any preceding clause, wherein the air pressure waves generated by the one or more air pressure wave generating elements are sound waves.

47. A device according to any preceding clause, wherein the control circuitry is configured to cause the one or more air pressure wave generating elements to generate air pressure waves with increased amplitude in response to identifying excessive background noise in the output from the one or more air pressure wave sensors.

48. A device according to any preceding clause, wherein a necessary condition for the control circuitry to determine the presence at the one or more air pressure wave sensors of said air pressure waves reflected as a result of flood water within, is that the one or more air pressure wave sensors indicate an air pressure wave amplitude greater than a threshold value.

49. A device according to Clause 48, wherein the control circuitry is configured to increase said threshold value in response to identifying excessive background noise in the output from the one or more air pressure wave sensors.

50. A device according to any preceding clause, wherein the control circuitry is configured to carry out a calibration, in which the control circuitry:

causes said one or more air pressure wave generating elements to generate air pressure waves, some of which are direct air pressure waves, which travel to the one or more air pressure wave sensors substantially without reflection by the chamber; and

in accordance with the output from the one or more air pressure wave sensors

corresponding to the direct air pressure waves, updates calibration data;

wherein said calibration data is used by the control circuitry in said determination of the level of flood water present within the test chamber. 51 . A device according to Clause 50, wherein said calibration data is used to account for variations in temperature and/or humidity.

52. A device according to any preceding clause, wherein said control circuitry is configured to periodically take readings of the level of flood-water.

53. A device according to clause 52, wherein the control circuitry is configured such that said readings are taken at a pseudo-random frequency.

54. A device according to clause 2 and one of clauses 52 or 53, wherein the control circuitry is configured to cause the transmitter to transmit data relating to a number of such readings, the frequency at which readings are taken being substantially higher than the frequency at which data is sent.

55. A device according to any preceding clause, wherein the control circuitry is configured to determine whether a warning condition that indicates that the device is being, or has been tampered with, should be triggered, based on the output from the one or more air pressure wave sensors.

56. A device according to Clause 55, wherein the control circuitry is configured to identify the presence of anomalous air pressure waves using the output from the one or more air pressure wave sensors, and to trigger such a warning condition in response.

57. A device according to Clause 55 or Clause 56, wherein the control circuitry is configured to determine whether the determined level of flood water is changing with respect to time at an anomalous rate and, and to trigger such a warning condition in response.

58. A device according to clause 2 and any one of clauses 55 to 57, wherein the control circuitry is configured to cause the transmitter to transmit data relating to the warning condition, preferably substantially immediately after the triggering thereof.

59. A device according to any one of clauses 55 to 58, further comprising a camera configured to capture images of the surroundings of the device; wherein the control circuitry is configured to cause the camera to capture an image in response to said warning condition being triggered.

60. A device according to clause 59, further comprising a light source, which is coupled to the control circuitry, the control circuitry being configured to cause the light source to illuminate the surroundings of the device when the camera to captures an image;

preferably wherein said light source comprises one or more LEDs. 61 . A device according to any preceding clause, when dependent upon clause 2, wherein the transmitter is configured to transmit data via electromagnetic radiation.

62. A device according to any preceding clause, when dependent upon clause 2, wherein the transmitter is configured to connect to a cellular telephone network.

63. A device according to any previous clause, wherein the device is configured to be mounted on a wall of a building.

64. A device according to any preceding clause, further comprising data storage, the control circuitry causing data relating to the determined height of water level to be stored on said data storage.

65. A device according to any preceding clause, further comprising at least one air pump, coupled to said control circuitry and configured to pump air into the at least one test chamber, the control circuitry being configured:

to cause the at least one pump to pump air into the at least one test chamber so as to drive out substantially all flood-water present therein, through said opening; and

to thereafter take one or more readings of the level of flood-water.

66. A device according to clause 65, wherein said one or more readings that follow the operation of the pump comprise:

one or more transient readings, each of which is taken while flood-water is returning to the at least one test chamber through said opening; and/or

at least one equilibrium reading, each of which is taken once the flood-water has reached a substantially constant level within the at least one test chamber.

67. A device according to any preceding clause, wherein the device is configured such that it can be mounted to a wall by embedding one or more elongate fasteners into the wall, the device being attached to the wall by the one or more fasteners in such a way that portions one or more fasteners not embedded within the wall are substantially covered by the device, with the one or more fasteners thus being inaccessible to a user;

optionally wherein at least some of the one or more fasteners are screws.

68. A device according to clause 14 and clause 67, wherein at least some of the portions of the one or more fasteners not embedded within the wall are substantially covered by the elongate member when the device is mounted to the wall, with the one or more fasteners thus being inaccessible to a user. 69. A device according to clause 67 or clause 68, wherein the device further comprises one or more fastener-receiving portions and one or more cover members;

wherein the one or more fastener-receiving portions are configured to receive said one or more fasteners, so as to mount the device to the wall; and

wherein the one or more cover members are connectable to one or more connecting portions of the device, which are adjacent the one or more fastener-receiving portions, the one or more cover members thus covering the portions of the one or more fasteners not embedded within the wall, in such a way that they are inaccessible to a user.

70. A device according to clause 69, wherein at least some of the fastener-receiving portions comprise mounting apertures; and

wherein the mounting apertures are configured such the one or more fasteners may be inserted through said mounting apertures, prior to embedding the one or more fasteners in the wall, so as to mount the device to the wall.

71 . A device according to clause 69 or clause 70, wherein the device further comprises one or more brackets, at least some of the one or more connecting portions being provided on the one or more brackets.

72. A device according to clause 71 , wherein each bracket connects with at least one cover member in such a way as to encircle the elongate member therebetween.

73. A device according to any one of clauses 69 to 72, wherein the connection formed between the one or more cover members and the one or more connecting portions cannot be disengaged without breaking or cutting part of the device.

74. The device according to any one of clauses 69 to 73, wherein the connection formed between the one or more cover members and the one or more connecting portions is a non return mechanical connection, preferably a snap-fit non-return connection.

75. A method of sensing the level of flood-water comprising:

providing a device comprising at least one test chamber, which has an opening through which flood water may enter;

generating air pressure waves within said at least one test chamber, flood water that has entered said at least one the test chamber causing the reflection of at least some of said generated air pressure waves;

detecting air pressure waves present within the at least one test chamber, including said air pressure waves reflected as a result of flood water that has entered the at least one test chamber; and determining the level of flood water present within the at least one test chamber based on the detected reflected air pressure waves.

76. A method according to clause 75, further comprising transmitting data relating to the thus-determined level of flood water.

77. A method according to clause 75 or clause 76, wherein the at least one test chamber is elongate.

78. A method according to clause 77, wherein the length of the test chamber is between about 0.5m and 5m.

79. A method according to clause 77 or clause 78, wherein the width of the test chamber is between about 3mm and 25mm,

80. A method according to any one of clauses 77 to 79, wherein the length of the test chamber is at least 20 times greater, preferably at least 100 times greater, and more preferably at least 1000 times greater than its width.

81 . A method according to any one of clauses 77 to 80, wherein said generating of air pressure waves and said detecting of air pressure waves occurs at or adjacent a first longitudinal end of the at least one test chamber.

82. A method according to clause 81 , wherein said opening is located at or adjacent a second, opposing longitudinal end of the at least one test chamber.

83. A method according to clause 82, wherein during said generating of air pressure waves and said detecting of air pressure waves, the device is oriented with the first longitudinal end of the at least one test chamber vertically above the second longitudinal end.

84. A method according to anyone of clauses 81 -83, wherein the device is configured for operation with the first longitudinal end of the at least one test chamber vertically above said opening in the chamber.

85. A method according to any one of clauses 75 to 84, wherein the device further comprises at least one reference chamber which is sealed so as to substantially prevent the entry of flood water, the method further comprising:

generating air pressure waves within said at least one reference chamber that are then reflected by the interior surfaces of the at least one reference chamber;

wherein said one or more air pressure wave sensors are configured to detect air pressure waves present within the reference chamber; and detecting air pressure waves present within the at least one reference chamber; wherein said determining the level of flood water present within the at least one test chamber is based on the detected reflected air pressure waves in the at least one test chamber and the detected reflected air pressure waves in the at least one reference chamber, and preferably is based on a comparison thereof.

86. A method according to clause 85, when dependent upon clause 77, wherein the at least one reference chamber is elongate.

87. A method according to clause 86, when dependent upon clause 81 , wherein said generating of air pressure waves and said detecting of air pressure waves occurs at or adjacent a first longitudinal end of the at least one reference chamber;

preferably wherein at least the majority of the air pressure waves that are generated within the at least one reference chamber are reflected by a second, opposing longitudinal end of the at least one reference chamber.

88. A method according to any one of clauses clause 85 to 87, wherein the at least one reference chamber has generally the same shape as the at least one test chamber.

89. A method according to any one of clauses 75 to 88, wherein the air pressure waves generated have a frequency of between 50Hz and 20 KHz, preferably between 2 KHz and 8 KHz.

90. A method according to any one of clauses 75 to 89, wherein generating air pressure waves within said at least one test chamber comprises generating a series of one or more pressure pulses; and

wherein said determining of the level of flood water present within the at least one test chamber is based on the time interval from said generating of the series of one or more pressure pulses to the detecting of the corresponding reflected air pressure waves.

91 . A method according to any clause 90, wherein determining the level of flood water present within the at least one test chamber based on the detected reflected air pressure waves comprises any pressure waves detected during a period of time after the generating of said series of one or more pressure pulses, said period of time preferably having a predetermined length.

92. A method according to any one of clauses 75 to 91 , wherein the air pressure waves generated by the one or more air pressure wave generating elements are sound waves. 93. A method according to any one of clauses 75 to 92, further comprising increasing the amplitude of the generated air pressure waves in response to identifying excessive background noise.

94. A method according to any one of clauses 75 to 93, wherein the device provided is the device according to any one of clauses 1 to 74.

95. A method for installing a device for sensing the level of flood-water, comprising the steps of:

providing a device according to any one of clauses 1 to 64; fixing the device at a chosen site, thus resulting in the device having a fixed elevation; and storing data relating to said fixed elevation.

96. The method of clause 95, wherein said data relating to the fixed elevation is stored remotely of the device.

97. The method of clause 95 or clause 96, wherein the device installed is a device according to any one of clauses 1 to 64, when dependent upon clause 14; and

wherein providing the device comprises selecting said elongate member from an inventory of differently-sized elongate members.

98. The method of clause 95 or clause 96, wherein the device installed is a device according to any one of clauses 1 to 64, when dependent upon clause 14; and

wherein providing the device comprises:

providing an elongate hollow component having a longitudinally extending lumen; and

removing a portion of the length of said elongate hollow component, with the remaining portion of the elongate hollow component providing the elongate member of the device and the elongate chamber of the device comprising the remaining portion of said longitudinally extending lumen.

99. The method of clause 98, wherein the device installed is a device according to any one of clauses 1 to 64, when dependent upon clause 28;

wherein the elongate hollow component further comprises a second longitudinally extending lumen; and

wherein providing said device further comprises:

blocking one longitudinal end of the remaining portion of the second lumen so as to provide said reference chamber, which is sealed so as to substantially prevent the entry of flood water.

100. The method of clause 99 wherein blocking said longitudinal end of the lumen comprises attaching a blocking element to said longitudinal end;

preferably wherein said blocking element is a plug that is inserted into said end, or a cap that is attached to said end.

101. The method according to any one of clauses 95 to 98, wherein the device installed is a device according to any one of clauses 1 to 64, when dependent upon clause 14; and

wherein fixing the device at a particular height comprises arranging the device such that the elongate member is angularly spaced from the horizontal, and preferably arranged substantially vertically.

102. The method according to clause 101 , wherein fixing the device at a chosen site comprises mounting the device on a wall at the chosen site.

103. The method according to clause 102, wherein mounting the device to a wall comprises embedding one or more elongate fasteners into the wall, the device being attached to the wall by the one or more fasteners in such a way that portions of the one or more fasteners not embedded within the wall are substantially covered by the device, with the one or more fasteners thus being inaccessible to a user;

optionally wherein at least some of the one or more fasteners are screws.

104. The method according to clause 102, wherein the device installed is a device according to any one of clauses 1 to 64, when dependent upon clause 14; and

wherein the device is attached to the wall by the one or more fasteners in such a way that at least some of the portions of the one or more fasteners not embedded within the wall are substantially covered by the elongate member with the one or more fasteners thus being inaccessible to a user.

105. The method according to clause 103 or clause 104, wherein the device further comprises one or more fastener-receiving portions and one or more cover members;

wherein mounting the device to the wall comprises receiving the one or more fasteners in the one or more fastener-receiving portions, and connecting the one or more cover members to one or more connecting portions of the device, which are adjacent the one or more fastener-receiving portions, the one or more cover members thus covering the portions of the one or more fasteners not embedded within the wall, in such a way that they are inaccessible to a user. 106. The method according to clause 105, wherein at least some of the fastener receiving portions comprise mounting apertures; and

wherein receiving the one or more fasteners in the one or more fastener receiving portions comprises inserting at least some of the one or more fasteners through said mounting apertures, prior to embedding the one or more fasteners in the wall.

107. The method according to clause 105 or clause 106, wherein the device further comprises one or more brackets, at least some of the one or more connecting portions being provided on the one or more brackets.

108. The method according to clause 107, wherein the device installed is a device according to any one of clauses 1 to 64, when dependent upon clause 14; and

wherein each bracket connects with at least one cover member in such a way as to encircle the elongate member therebetween.

109. The method according to any one of clauses 105 to 108, wherein following said step of connecting the one or more cover members to the one or more connecting portions of the device, the one or more cover members cannot be disconnected without breaking or cutting part of the device.

1 10. The method according to any one of clauses 105 to 109, wherein connecting the one or more cover members to the one or more connecting portions of the device forms a non return mechanical connection, preferably a snap-fit non-return connection.

1 1 1. The method according to any of clauses 95 to 1 10, further comprising the step of providing, to the control circuitry, adjustment data, which is determined based on the length of the elongate member;

wherein said adjustment data is used by the control circuitry in said determination of the level of flood water present within the test chamber.

1 12. The method according to Clause 1 1 1 , wherein providing adjustment data to the control circuitry comprises entering data relating to the length of the elongate member into a handheld device, the handheld device then causing the transmission of said adjustment data to the control circuitry;

optionally wherein said handheld device is a smartphone.

1 13. The method according to Clause 1 12, wherein the handheld device determines said adjustment data and transmits it to the control circuitry.

Claims

1. A device for sensing the level of flood water, comprising:

to determine the level of such flood water present within the test chamber, based on the resulting output from said one or more air pressure wave sensors, including the output corresponding to said air pressure waves reflected as a result of the flood water;

wherein the device is mounted on a wall of a building.

2. A device according to claim 1 , further comprising a transmitter coupled to said control circuitry and configured to transmit data; wherein said control circuitry is further configured to cause said transmitter to transmit data relating to the thus-determined level of flood water.

3. A device according to any preceding claim, further comprising at least one reference chamber which is sealed so as to substantially prevent the entry of flood water;

4. A device according to claim 3, wherein the control circuitry is configured to carry out a calibration, in which the control circuitry:

in accordance with the output from the one or more air pressure wave sensors

wherein said calibration data is used by the control circuitry in said determination of the level of flood water present within the at least one test chamber, wherein said calibration data is used to account for variations in temperature and/or humidity.

5. A device according to any preceding claim, wherein the control circuitry is configured to determine whether a warning condition that indicates that the device is being, or has been tampered with, should be triggered, based on the output from the one or more air pressure wave sensors.

6. A device according to Claim 5, wherein the control circuitry is configured to identify the presence of anomalous air pressure waves using the output from the one or more air pressure wave sensors, and to trigger such a warning condition in response.

7. A device according to Claim 5 or Claim 6, wherein the control circuitry is configured to determine whether the determined level of flood water is changing with respect to time at an anomalous rate and, and to trigger such a warning condition in response.

8. A device according to claim 2 and any one of claims 5 to 7, wherein the control circuitry is configured to cause the transmitter to transmit data relating to the warning condition, preferably substantially immediately after the triggering thereof.

9. A device according to any one of claims 5 to 8, further comprising a camera configured to capture images of the surroundings of the device; wherein the control circuitry is configured to cause the camera to capture an image in response to said warning condition being triggered.

10. A device according to any preceding claim, further comprising data storage, the control circuitry causing data relating to the determined height of water level to be stored on said data storage.

1 1 . A device according to any preceding claim, wherein the device is configured such that it can be mounted to a wall by embedding one or more elongate fasteners into the wall, the device being attached to the wall by the one or more fasteners in such a way that portions one or more fasteners not embedded within the wall are substantially covered by the device, with the one or more fasteners thus being inaccessible to a user;

optionally wherein at least some of the one or more fasteners are screws.

12. A device according to claim 1 1 , wherein at least some of the portions of the one or more fasteners not embedded within the wall are substantially covered by the elongate member when the device is mounted to the wall, with the one or more fasteners thus being inaccessible to a user.

13. A device according to claim 1 1 or claim 12, wherein the device further comprises one or more fastener-receiving portions and one or more cover members;

14. A device according to claim 13, wherein at least some of the fastener-receiving portions comprise mounting apertures; and

15. A device according to claim 13 or claim 14, wherein the device further comprises one or more brackets, at least some of the one or more connecting portions being provided on the one or more brackets.

16. A device according to claim 15, wherein each bracket connects with at least one cover member in such a way as to encircle the elongate member therebetween.

17. A device according to any one of claims 13 to 16, wherein the connection formed between the one or more cover members and the one or more connecting portions cannot be disengaged without breaking or cutting part of the device.

18. The device according to any one of claims 13 to 17, wherein the connection formed between the one or more cover members and the one or more connecting portions is a non return mechanical connection, preferably a snap-fit non-return connection.

19. A method of sensing the level of flood-water comprising:

providing a device attached to the wall of a building; where the device comprises at least one test chamber, which has an opening through which flood water may enter;

detecting air pressure waves present within the at least one test chamber, including said air pressure waves reflected as a result of flood water that has entered the at least one test chamber; and

determining the level of flood water present within the at least one test chamber based on the detected reflected air pressure waves, and so determining the level of flood water at the building.

20. A method according to claim 19, further comprising transmitting data relating to the thus- determined level of flood water.

21 . A method according to any one of claims 19 to 20, wherein the device further comprises at least one reference chamber which is sealed so as to substantially prevent the entry of flood water, the method further comprising:

wherein said one or more air pressure wave sensors are configured to detect air pressure waves present within the reference chamber; and

detecting air pressure waves present within the at least one reference chamber; wherein said determining the level of flood water present within the at least one test chamber is based on the detected reflected air pressure waves in the at least one test chamber and the detected reflected air pressure waves in the at least one reference chamber, and preferably is based on a comparison thereof.

22. A method according to any one of claims 19 to 21 , wherein the device provided is the device according to any one of claims 1 to 18.

23. A method for installing a device for sensing the level of flood-water, comprising the steps of:

providing a device according to any one of claims 1 to 18; fixing the device to the wall of a building, thus resulting in the device having a fixed elevation; and storing data relating to said fixed elevation.

24. The method of claim 23, wherein said data relating to the fixed elevation is stored remotely of the device.

25. The method according to any of claims 23 to 24, wherein mounting the device to the wall of the building comprises embedding one or more elongate fasteners into the wall, the device being attached to the wall by the one or more fasteners in such a way that portions of the one or more fasteners not embedded within the wall are substantially covered by the device, with the one or more fasteners thus being inaccessible to a user;

optionally wherein at least some of the one or more fasteners are screws.

26. The method according to 25, wherein the device further comprises one or more fastener receiving portions and one or more cover members;

wherein mounting the device to the wall comprises receiving the one or more fasteners in the one or more fastener-receiving portions, and connecting the one or more cover members to one or more connecting portions of the device, which are adjacent the one or more fastener-receiving portions, the one or more cover members thus covering the portions of the one or more fasteners not embedded within the wall, in such a way that they are inaccessible to a user.

27. The method according to any one of claims 26, wherein following said step of connecting the one or more cover members to the one or more connecting portions of the device, the one or more cover members cannot be disconnected without breaking or cutting part of the device.

28. The method according to any of claims 23 to 27, further comprising the step of providing, to the control circuitry, adjustment data, which is determined based on the length of the elongate member;

29. The method according to Claim 28, wherein providing adjustment data to the control circuitry comprises entering data relating to the length of the elongate member into a handheld device, the handheld device then causing the transmission of said adjustment data to the control circuitry;

optionally wherein said handheld device is a smartphone.

30. A system for sensing the level of flood water, comprising:

a device;

and a wall of a building, wherein the device is mounted on the wall of the building, and where the device is configured to detect the presence of flood water;

the device comprising: