System and method for automatically detecting unauthorized entry into a pool

A system and method for automatically detecting unauthorized entry into a pool requiring no user involvement, and having a high degree of accuracy. The system comprises a plurality of light beam emitter devices and a plurality of light beam receiver devices positioned about the pool and a processor in communication with the plurality of light beam emitter devices and the plurality of light beam receiver devices. The plurality of light beam emitter devices emit a plurality of light beams and the plurality of light beam receiver devices receive a plurality of emitted light beams to form a grid extending across a the pool. Additionally, the processor monitors the grid, detects unauthorized entry into the pool based on an interruption of the grid, and generates and transmits an alarm message based on whether a level of the interruption of the grid exceeds a predetermined threshold.

FIELD OF THE INVENTION

The present disclosure relates generally to the field of pool safety systems. More specifically, the present disclosure relates to a system and method for automatically detecting unauthorized entry into a pool.

BACKGROUND OF THE INVENTION

Conventional pool safety systems can be unreliable because of a dependency on user monitoring and the frequent false detection of motion in a pool. Additionally, conventional systems generally use a beam break detection and usually use a single band. As such, there is currently an interest in the field of pool safety in developing a motion detecting pool safety system that automatically detects unauthorized entry into a pool requiring no user involvement, and having a high degree of accuracy.

SUMMARY OF THE INVENTION

The present disclosure relates to a system and method for automatically detecting unauthorized entry into a pool requiring no user involvement, and having a high degree of accuracy. The system can, upon determining the detected unauthorized entry into the pool, automatically generate and transmit an alarm message to a remote device of a user and/or to a house alarm system.

The system comprises a plurality of light beam emitters, such as infrared light beam emitters, and a plurality of corresponding receivers, positioned along a perimeter of a pool, and a processor in communication with the plurality of emitter and receiver devices. The plurality of emitters and receivers form a grid extending over, on or below the water surface in a pool. The processor monitors the grid, detects unauthorized entry into the pool based on an interruption of one or more of the light beams forming the grid, and determines whether a level of the interruption of the grid exceeds a predetermined threshold. Thresholds can be set or adjusted by a user. The processor generates and transmits an alarm message to a remote device and/or a home alarm system when the level of the interruption of the grid exceeds the predetermined threshold.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A system and method is disclosed for automatically detecting unauthorized entry into a pool requiring no user involvement, and having a high degree of accuracy, as described in detail below in connection withFIGS.1-4.

Turning to the drawings,FIG.1is a diagram illustrating the system10. The system10comprises a plurality of emitters14aand a corresponding plurality of receiving devices14b. Each of the emitters14aemits a light beam16such as an infrared light beam, and each of the corresponding receivers14breceives a corresponding light beam16to form a grid18of light beam16extending across a pool12. The emitter and receiver devices14a,14bcould be positioned above or below a surface of the water (i.e., a waterline of the pool) along an interior perimeter of the pool12. For example, the emitter and receiver devices14a,14bcould be built into or attached to, a pool wall, pool coping or pool deck above or below the pool waterline. Any suitable light beam can be used, or any other type of point to point connection that can be interrupted by an object passing between the points, e.g. a laser, can be used for the detection system of the present disclosure.

The system10automatically detects unauthorized entry into the pool12when the system10detects an interruption of the grid18(e.g., an interruption of two or more adjacent light beams16forming the grid18). If the system10determines that the number of interrupted light beams16exceeds a predetermined threshold, then the system10generates and transmits an alarm message to a remote device of a user (e.g., a pool owner) and/or a home alarm system. The remote device can include, but is not limited to, a personal computer, a laptop computer, a tablet computer and a smart telephone. The alarm message can notify the user of a potential drowning incident in the pool12. Accordingly, the system10can automatically detect unauthorized entry into the pool12requiring no user involvement, and having a high degree of accuracy.

Thresholds level can be set and/or adjusted by the user. Threshold levels can cones to the number of light beams interrupted. The interruption of one light beam would provide for a very sensitive system, but could result in unwanted false alarms. For example, a sensitive system could suffer from false alarms from high winds, splashing water, small animals, insects, twigs or other debris, moths, birds, etc. A threshold requiring interruption of two or beams would significantly drop the chance of false alarms. Increasing the threshold too high could interfere with the functionality of sensor. Of course, the sensitivity depends on the spacing between adjacent light beams.

FIG.2is a diagram illustrating the emitter device14aof the system10andFIG.2Ais a diagram illustrating the receiver device14bof the system10. The emitter and receiver devices14a,14brespectfully comprise a front housing30a,30b, a cover32a,32b, and a rear housing34a,34b. Additionally, the emitter device14acomprises a light beam emitting portion36and the receiver device14bcomprises a light beam receiving portion38.

The emitter and receiver devices14a,14bcould include a cable attachment cord for supplying power to the emitter and receiver devices14a,14b. It should be noted that the emitter and receiver devices14a,14bcould be any shape including, but not limited to, a rectangle, a square, a circle, a diamond, etc.

The rear housing34a,34bcould be constructed of a thermally conductive and electrically insulative polymer material. Such a material could include, but is not limited to, electrically insulative and thermally conductive materials (e.g., plastic). In addition, the rear housing34a,34bcould also be constructed of a chemical resistant material including, but not limited to, urethane, thermoplastic elastomer (TPE) overmolding, silicone or polyamide.

The front housing30a,30bcould couple to the rear housing34a,34bvia a plurality of mounting apertures and a plurality of screws (not shown) to form a watertight chamber between the front housing30a,30band the rear housing34a,34b. It should be noted that the front housing30a,30bcould be coupled to the rear housing34a,34bvia any suitable means including, but not limited to, a plurality of tabs, an adhesive, tape, magnets, sonic welding, etc. Still further, if the emitter and receiver devices14a,14bare a circular shape, then the front housing30a,30bcould be coupled to the rear housing34a,34bby way of a watertight threaded connection, i.e., the front housing30a,30bcould be threaded onto the rear housing34a,34band vice versa. This connection could also be by any suitable means including, but not limited to, a plurality of tabs, an adhesive, tape, magnets, sonic welding, etc. The front housing30a,30bcould be constructed of a thermally conductive and electrically insulative polymer material. Such a material could include, but is not limited to, electrically insulative and thermally conductive materials (e.g., plastic).

The cover32a,32bcould be formed using a suitable manufacturing process (e.g., injection molding, compression molding, thermoforming, etc.). The cover32a,32bcould be formed from any suitable, electrically-insulating material, such as glass or a polymeric material (e.g., plastic). Such a material could include, but is not limited to, amorphous transparent copolymer having a cyclic olefin copolymer copolymerized from norbornene and ethylene using a metallocene catalyst and possessing properties important in optical components such as lenses. Such material possesses properties including, but not limited to, high transparency, low birefringence, high flowability for precision molding, high heat resistance and negligible water absorption.

Advantageously, the electrically non-conductive nature of the exterior components of the emitter and receiver devices14a,14bof the system10(i.e., the front housing30a,30b, the cover32a,32b, and the rear housing34a,34b) permit the emitter and receiver devices14a,14bto be installed in any location in a pool or spa. Further, since the exterior of the emitter and receiver devices14a,14bare electrically non-conductive, no specific bonding or grounding of the emitter and receiver devices14a,14bis necessary.

The emitting portion36can emit a light beam16and the receiving portion38can receive an emitted light beam16to form a grid18across the pool12. The emitting portion36and the receiving portion38could be encapsulated in an optically transparent potting compound (not shown). The potting compound protects the emitting portion36and the receiving portion38from exposure to water in the event that the emitter and receiver devices14a,14bare no longer watertight, thereby protecting against electrical shock and promoting safety. The rear housing34a,34bcould comprise the electronics (not shown) of the emitting portion36and the receiving portion38. It is noted that the emitter and receiver devices14a,14bcould be positioned on one of a pool wall, pool coping and pool decking along the interior perimeter of the pool12.

FIG.3is a flowchart illustrating processing steps60carried out by the system10ofFIG.1. The system10provides for automatically detecting unauthorized entry into the pool12requiring no user involvement, and having a high degree of accuracy. Additionally, the system10can, upon determining the detected unauthorized entry into the pool12, automatically generate and transmit an alarm message to a remote device and/or a home alarm system.

Beginning in step62, the system10initiates the grid18by controlling the emitter and receiver devices14a,14bto emit and receive a plurality of light beams16. Then, in step64, the system10monitors the grid18. In step66, the system10determines whether unauthorized entry into the pool12has been detected. The system10automatically detects unauthorized entry into the pool12when the system10detects an interruption of the grid18(e.g., an interruption of at least one of the plurality of light beams16forming the grid18). If the system10determines that unauthorized entry into the pool12has not been detected, then the system10returns to step64and monitors the grid18. However, if the system10determines that unauthorized entry into the pool12has been detected, then the system10proceeds to step68.

In step68, the system10determines whether the detected interruption of the grid18exceeds a predetermined threshold. Specifically, the system10determines whether a number of interrupted light beams16(i.e., light beams16that are not received by their corresponding receiver devices14) exceeds a predetermined threshold of interrupted light beams16. If the system10, determines that the number of interrupted light beams16does not exceed the predetermined threshold of interrupted light beams16, then the system returns to step64and monitors the grid18. However, if the system10determines that the number of interrupted light beams16exceeds the predetermined threshold of interrupted light beams16, then the system10proceeds to step70.

In step70, the system10generates and transmits an alarm message to a remote device of a user (e.g., a pool owner) and/or to a home alarm system. The alarm message can notify the user of a potential drowning incident in the pool12. Accordingly, the system10can automatically detect unauthorized entry into the pool12requiring no user involvement, and having a high degree of accuracy.

FIG.4is a diagram illustrating hardware and software components capable of being utilized to implement the system10. The system10can include a communications bus80, a storage device82, pool safety code84, a plurality of emitter and receiver devices14a,14b, a central processing unit (CPU)86, an alarm module88, a network interface90and one or more input devices92including, but not limited to, a keyboard, a mouse, etc.

The functionality provided by the system10of the present disclosure could be provided by the pool safety program84, which could be embodied as computer-readable program code stored on the storage device82and executed by the CPU86using any suitable, high or low level computing language, such as Python, Java, C, C++, C#, .NET, MATLAB, etc. Accordingly, execution of the pool safety program84is configured to control operation of the plurality of emitter and receiver devices14a,14band the alarm module88. The alarm module88generates and an alarm message that can be transmitted to one or more of a remote device of the user, a home alarm system and a monitoring station.

The network interface90could include an Ethernet network interface device, a wireless network interface device, or any other suitable device which permits the system10to communicate via a network to a remote device of the user including, but not limited to, a personal computer, a server, a smart phone, tablet computer etc. The CPU86could include any suitable single-core or multiple-core microprocessor of any suitable architecture that is capable of implementing and running the pool safety program84(e.g., Intel processor).

A further embodiment of the present invention is shown inFIGS.5-10.

According to an embodiment of the present invention, referring toFIGS.5-9, there is shown a swimming pool safety system110(“safety system”) configured to easily and conveniently installed on an existing swimming pool112and provides an automatic detection of unauthorized entry into the swimming pool112with a high degree of accuracy and without any user involvement. The safety system110includes a plurality of first overlay structures114, a plurality of second overlay structures116, and a control system18capable of communicating with the first and second overlay structures114,116. The plurality of first overlay structures114and the plurality of second overlay structures116are designed and configured to be installed on top of a swimming pool coping120, as will be described in greater detail below.

Referring again toFIGS.5-9, each of the plurality of first overlay structures114includes a first body member122and a plurality of light beam emitter devices124mounted on the first body member122. In the depicted embodiment, each of the plurality of first overlay structures114has a top wall126and a front wall128transitioning into the top wall126. The top wall126and front wall128extend between a first end and a second end of the first overlay structure114. In the depicted embodiment, the front wall128is arcuate. However, the top and front walls126,128of the overlay structure114may be constructed in any suitable shape to overlay the swimming pool coping120.

A plurality of apertures130are defined on the front wall128with an evenly spaced distance therebetween. Each of the plurality of light beam emitter devices124is mounted on the first overlay structure114via its corresponding aperture130. In depicted embodiment, each of the plurality of light beam emitter devices124is mounted such that the emitter device124is disposed on an inner surface of the front wall128of the first overlay structure114. Alternately, the plurality of light beam emitter devices124may be mounted on an outer surface of the front wall28of the first overlay structure114.

As shown inFIG.7, the plurality of second overlay structures116are substantially identically to the plurality of first overlay structures114except that a plurality of light beam receiver devices132are mounted on a second body member134of the second overlay structure116via its corresponding aperture130.

Referring particularly toFIGS.5,6and7, the plurality of first overlay structures114are overlaid and installed on top of the swimming pool coping120with the plurality of second overlay structures116being overlaid and installed on top of the swimming pool coping120opposite the plurality of first overlay structures114such that each of the first overlay structure114faces its corresponding second overlay structure116. The design and configuration of the first and second overlay structures114,116allow easy and convenient installation of the emitter and receiver devices124,132on the existing swimming pool112since the devices124,132do not need to be installed on the side walls of the swimming pool112.

The plurality of first overlay structures114and the plurality of second overlay structures116may be attached to the swimming pool coping120using any known attachment mechanisms. Non-limiting examples of the attachment mechanism includes adhesive, screws, Velcro, and magnets. In a preferred embodiment shown inFIG.5, the first overlay structures114are positioned along one enclosed side of the swimming pool coping120, and the second overlay structures116are positioned along the opposite enclosed side of the swimming pooling coping120.

Referring again toFIG.8, in the depicted embodiment, the plurality of first overlay structures114and the plurality of second overlay structures116are designed and constructed such that, when they are overlaid and installed on top of the swimming pool coping120, spaces are created between each of the first and second overlay structures114,116and the swimming pool coping120. Specifically, a first space136is created between the front wall128of the overlay structure114,116and a front portion of the swimming pool coping120. Additionally, a second space138is formed between the top wall126of the overlay structure114,116and a top portion of the swimming pool coping120. The spaces136,138allow the light beam emitter devices124, light beam receiver devices132, and wires (not shown) to be disposed therewithin.

Alternately, the plurality of first overlay structures114and the plurality of second overlay structure116are designed and constructed such that the top wall126of the overlay structure14,16is flushed with (or attached directly to) the top portion of the swimming pool coping120, thereby creating only the first space136between the front wall128of the overlay structure114,116and the front portion of the swimming pool coping120, as shown inFIG.9.

The first overlay structures114, second overlay structures116, emitter devices124, and receiver devices132are made of one or more materials having suitable properties for a desired application, including strength, weight, rigidity, etc. Thermally conductive and electrically insulative polymer materials (e.g., plastic) are preferred. Since the emitter and receiver devices124,132are electrically non-conductive, no specific bonding or grounding of the emitter and receiver devices124,132is necessary.

Referring back toFIG.5, each of the plurality of light beam emitter devices124emits a light beam125such as an infrared light beam, and each of the corresponding light beam receiver132devices receives the light beam125from its corresponding light beam emitter device124to form a grid of the light beams125, extending across the swimming pool112above a swimming pool waterline. Any suitable light beam or any type of point-to-point connection that can be interrupted by an object passing between the points (e.g., a laser) may be used to form the grid over the swimming pool112.

The emitter and receiver devices124,132may include wire (not shown) for supplying power to the emitter and receiver devices124,132. The emitter and receiver devices124,132may be constructed in any shape form including, but not limited to, a rectangle, a square, a circle, etc.

FIG.10is a diagram illustrating the control system118of the safety system110capable of communicating with the plurality of emitter devices124and plurality of receiver devices132. The control system118may include a communications bus140, a storage device142, pool safety program144, a central processing unit (CPU)146, an alert module148, a network interface150, and one or more input devices152including, but not limited to, a keyboard, a mouse, etc.

The functionality provided by the control system118of the present disclosure is provided by the pool safety program144, which may be embodied as computer-readable program code stored on the storage device142and executed by the CPU146using any suitable, high or low level computing language, such as Python, Java, C, C++, C#, .NET, MATLAB, etc. Accordingly, execution of the pool safety program144is configured to control operation of the plurality of emitter and receiver devices124,132and the alert module148. The alert module148generates and an alert that can be transmitted to one or more of a remote computing device of the user, a home alarm system, and a monitoring station. The alert may be a displayed message and/or an audible alert that notify the user of a potential drowning incident in the swimming pool112.

The network interface150may include an Ethernet network interface device, a wireless network interface device, or any other suitable device that permits the control system118to communicate via a network to a remote computing device of the user. The CPU146may include any suitable single-core or multiple-core microprocessor of any suitable architecture that is capable of implementing and running the pool safety program144(e.g., Intel processor).

As stated above, the control system118is configured to communicate with the plurality of first overlay structures114and the plurality of second overlay structures116. Specifically, the control system118communicates with the plurality of light beam emitter devices124and the plurality if light beam receiver devices132to detect unauthorized entry into the swimming pool112. The control system118controls the plurality of light beam emitter devices124to emit a plurality of light beams125and the plurality of light beam receiver devices132to receive the plurality of emitted light beams125to form a grid extending across the swimming pool112. The control system118monitors the grid and detects the unauthorized entry into the swimming pool112based on an interruption of the light beams125of the grid. If the control system118determines that the number of interrupted light beams exceeds a predetermined threshold of interrupted light beams, then the control system118generates and transmits an alert to a remote computing device of a user (e.g., a swimming pool owner) and/or a home alarm system. The alert can notify the user of a serious incident (e.g., drowning incident) in the swimming pool. Non-limiting examples of remote computing devices include a personal computer (laptop or desktop), mobile phone (smartphones), tablets, personal digital assistants (PDA), or other similar devices. The remote computing devices will typically access the control system118directly through an Internet service provider (ISP) or indirectly through another network interface.

The predetermined threshold may be set and/or adjusted by the user. The predetermined threshold is the number of interrupted light beams of the grid. The interruption of one light beam would provide for a very sensitive system and may result in unwanted false alerts. For example, the false alerts may be generated from movements from high winds, splashing water, small animals, insects, debris, etc. A threshold requiring interruption of two or more beams significantly reduce the false alerts. The sensitivity of the system depends on the spacing between the light beams125of the grid.

In use of the safety system110, first, the plurality of first overlay structures114are installed on top of the swimming pool coping120. Then, the plurality of second overlay structures116are installed on top of the swimming pool coping120opposite the plurality of first overlay structures114such that each of the first overlay structures114faces its corresponding second overlay structure116.

The control system118initiates the grid by controlling the emitter and receiver devices124,132to emit and receive a plurality of light beams125. Then, the control system118monitors the grid. The control system118determines whether unauthorized entry into the swimming pool112has been detected. The control system118automatically detects unauthorized entry into the swimming pool112when the control system118detects an interruption of the grid (e.g., an interruption of at least one of the plurality of light beams125forming the grid).

If the control system118determines that unauthorized entry into the swimming pool112has not been detected, then the control system118continues to monitor the grid118. However, if the control system118determines that unauthorized entry into the swimming pool112has been detected, then the control system118proceeds to determine whether the detected interruption of the grid exceeds a predetermined threshold. Specifically, the control system118determines whether a number of interrupted light beams (i.e., light beams that are not received by their corresponding receiver devices132) exceeds a predetermined threshold of interrupted light beams.

If the control system118, determines that the number of interrupted light beams does not exceed the predetermined threshold of interrupted light beams, then the control system118continues to monitor the grid. However, if the control system118determines that the number of interrupted light beams exceeds the predetermined threshold of interrupted light beams, then the control system118proceeds to generate an alert.

From the foregoing, it will be appreciated that a swimming pool safety system according to the present invention can be easily and conveniently installed on an existing swimming pool and provides an automatic detection of unauthorized entry into the swimming pool with a high degree of accuracy and without any user involvement.

Further embodiments and features of the present invention may now be described.

Referring toFIGS.11-13, this embodiment places the above described emitter module (emitter)210and receiver module (receiver)212constituting a beam214as described above under the water216.

The emitter210would consist of a down firing visible laser diode with focusable collimating lens218with a fold mirror220to point the beam214parallel to the water in a watertight housing222with a watertight window224which the beam214will pass through. The emitter module210would be placed over the vinyl liner219. This design minimizes the distance the module protrudes laterally into the pool, for both aesthetic and damage mitigation reasons and keeps the wiring and electronics226above the water line.

Referring also toFIG.13, the receiver module212will be housed in a similar looking watertight housing230placed over the vinyl liner219with a watertight window231, which will transmit the beam214, behind which will sit a collection lens and photodiode receiver232to convert the beam214sent by the emitter module210having traversed the pool unbroken into an electrical signal to be processed by the wiring and electronics266which are housed above the waterline.

The emitter and receiver modules210,212can be attached to the coping240through a variety of means. The depth of the beam would be roughly 6 inches below the nominal surface of the water. Low enough to avoid false alarms due to waves caused by wind, the displacement of unoccupied floating accessories, or animals drinking, but high enough to capture unauthorized entry into the pool.

As mentioned above, it is expected that any above water versions of this system would require multiple beams along any given side of the pool to ensure multiple beam breaks during unauthorized entry to protect against false alarms. Given its resistance to false alarms inherent in similar above water systems, it maybe be possible and preferable to reduce the number of beams along any side of the pool, possibly only requiring a single beam along any side of rectangular pools. This would be a cost savings in both materials and installation time. This embodiment requires an understanding of the electromagnetic spectrum and its transmission through water, it is important to understand the preferred wavelength of light for transmission under the water is in the visible portion of the spectrum (see Optical Absorption of Water Compendium https://omlc.org/spectra/water/abs/index.html).

The light array can be situated to make the level of detection greater or less through spacing of the light array. User can choose one light beam (least secure from false alarms) or use multiple linked beams for enhanced control of false alarms. By adding beams of light the user can choose any multiple of emitting linked beams to be broken simultaneously which would lessen false alarms. For example, three beams at 6″ apart would create an alarm only when all three lines are broken or something larger than 1 ft in length or diameter would cross those three lines. Obviously one could choose to add more light beams and more break points or less light beams with less break points. It is also understood that using less line breaks and simply spreading the emitting beams farther apart would achieve similar results. Depending on pool usage, elderly assisted living home you could use less beams since the users are all adults and a larger spread of those beams would be safe for full grown adults. Of course, that would reduce the detection smaller object or a child but having the light array wider would significantly reduce false alarms.

FIG.13Ashows our calculations based on the formulas provide in the reference above regarding the percent transmission per foot through liquid water and the transmission through 20, 40, and 80 feet representing various length pools. This shows using emitters with wavelengths that fall in the 400 to 560 nm range or Blue to Green. There are a number of mass produced Lasers and LEDs that fall within this range. Further benefits include ease of alignment between the emitter and receiver as the installer is able to see the beam without the use of special tools as is required in the InfraRed. Lastly, some percentage of the energy lost due scattering small bubbles and particles in the water will provide a pleasing blue or green illumination, also indicating the presence of an alarm system to would be intruders.

Referring toFIG.14, another embodiment of the present invention places the above mentioned emitter and receiver modules210,212in vertically holes drilled holes250into the surrounding concrete fill252to a depth of roughly six inches below the water line and a second horizontally drilled hole251that meets the mating vertically drilled hole250for a cross drilled hole pattern. The horizontally drilled holes251will be below the nominal water line and will penetrate through the vinyl or other surface of the pool219and will have a watertight sealing window257which will transmit the beam to the receiver having a matching set of drilled holes and window. The horizontal hole251may include a support tube (not shown) to reinforce the surrounding dirt or concrete to prevent settling from closing the horizontal hole. This embodiment has the benefit of being a more discrete and robust installation.

In still another embodiment shown inFIGS.15and16, a single module260which places the visible laser diode with focusable collimating lens218and fold mirror220adjacent to the photodiode receiver with collection lens221in the same watertight housing262behind a shared water tight window264being controlled by common wiring and electronics266. The beam214generated by the emitter will traverse the pool and be reflected by a retro reflective material280which will ensure the beam returns to the location it was sent from regardless of small angular misalignments of reflector, i.e., the reflector is not normal (perpendicular) to the beam.

The retro reflective material280is readily available and generally used to increase the contrast of an object in dark conditions for safety reasons, for example the perimeter of road signs or strips on construction apparel. Retro reflective material280has the unique ability to send light back where it came from as opposed to a mirror which redirects light based on the angle at which the light strikes it. The inclusion of this optical technique in this manner enables the improvements described.

This embodiment has the advantage of cutting the number of required modules for any number beams in half thus reducing material cost. It also greatly simplifies the installation by only requiring wiring and module installation on two sides of the pool, and the far simpler Retro Reflector installation on the other two sides.

This embodiment could be implemented in both above and below water versions of the alarm system in the visible or infrared spectrum. Any version of this embodiment could be installed mounted to the coping as shown inFIG.11or into cross drilled holes as demonstrated inFIG.14.

An additional embodiment includes components from any of the above-mentioned embodiments with the addition of a narrow waveband (narrowband) filter to limit the receiver sensitivity to only the waveband in the beam produced by the emitter. Use of narrowband filter will improve the rejection of momentary changes in ambient light conditions preventing false alarms.

Examples of changing ambient light conditions include lights from cars driving by and the sun coming in and out of clouds. Further improvements to ambient light rejection can be gained by encoding the beam as modulated signal. This would consist of pulsing the beam on and off at a rapid rate such that the time between the beams in insignificant with respect to falling object detection. This pulsing could be a constant pattern such as a sinusoid or square wave pattern, or could be a more complex signal which could be programmed to indicate which emitter it came from, this unique pattern would be the emitters signature.

Placing the grid of beams below the surface of the water assists in reducing false alarms. The depth below the surface being as low as possible to avoid uncovering by small waves, drinking by animals etc., while being high enough to guarantee detection of a buoyant.

Other features of the present invention are set forth as follows.

The emitters producing the beams may be of a visible wavelength given their superior transmission through water.

The receiver may include a photodiode with a narrow bandpass filter matching the wavelength of the emitter.

The beams may be modulated at a high frequency to create an AC signal or alternatively a more complex pulsed signature at the photodiode as means of rejecting changes in ambient light triggering false alarms.

It is contemplated that only single beams along the perimeter may be needed.

The emitter and receiver for a given beam may be placed adjacent to each other in the same module or submodule, where the beam is reflected from the other side of the pool using highly efficient retro reflective material or similar means back to the adjacent receiver. Such a configuration would decrease manufacturing costs by packaging the emitters and receivers together with a shared housing and electronics. Installation would be simplified as there are fewer modules to physically locate and run power and communications to.

The emitter and receivers may be placed in cross drilled holes in the cement (or similar) fill surrounding the pool to improve aesthetics and robustness.

While the preferred embodiment of the present invention has been described with respect to inground pools it is contemplated that the present invention may also be used with respect to above ground pools.

Having thus described the system and method in detail, it is to be understood that the foregoing description is not intended to limit the spirit or scope thereof. It will be understood that the embodiments of the present disclosure described herein are merely exemplary and that a person skilled in the art can make any variations and modification without departing from the spirit and scope of the disclosure. All such variations and modifications, including those discussed above, are intended to be included within the scope of the disclosure. What is desired to be protected is set forth in the following claims.