Patent Publication Number: US-6989752-B2

Title: Methods and apparatus for a security system

Description:
CROSS-REFERENCE 
   The present application claims benefit of U.S. Provisional Patent Application No. 60/303,647, filed on Jul. 7, 2001. U.S. Provisional Patent Application No. 60/303,647 filed on Jul. 7, 2001 is incorporated herein, in its entirety, by this reference. 

   BACKGROUND 
   This invention relates to improved methods and apparatus for security systems for movable items. 
   There are numerous situations requiring reliable and efficient methods and apparatus for security systems such as those for monitoring children, the mentally handicapped, pets or other animals, and inanimate objects such as electronic devices like computers, and particularly laptop computers. In other words, security systems are needed for items that are movable or are otherwise portable so as to aid in preventing the loss of the items as a result of abductions and theft. 
   Regarding the problem of child security, every year there are tens of thousands of cases of missing children. A large fraction of those reported cases involve child abductions by either a family member or a stranger. Although the reasons for the abductions are varied as are the final outcome, child abduction is a situation that every parent wishes to avoid. Indeed, for the worst cases, it is not merely abduction; it is usually abduction and murder. This is a very serious and very unpleasant occurrence in society. 
   Various technologies have been developed for use in providing security for children or other items that are being monitored. Many of the standard technologies involve some type of alarm that is sounded when a child or other item being monitored is believed to be in danger of being abducted, lost, or stolen. However, the standard technologies have shortcomings that reduce their effectiveness in providing security. Some of the standard technologies are very complex and may be expensive to implement. Alternatively, some of the standard technologies are easily defeated by an abductor. Furthermore, some of the standard technologies are not highly suitable for handling false alarms. Lastly, some of the standard technologies are not very suitable for use with younger children such as children less than about 10 years old and still less suitable for children in the age range from about 1–5 years old. 
   There is a need for improved methods and apparatus for providing security for children as well as other items that are being monitored. Particularly, there is a need for methods and apparatus that overcome one or more of the deficiencies of the standard technologies for monitoring children as well as for monitoring other items. 
   SUMMARY 
   Embodiments of the present invention seek to provide methods and apparatus that can overcome one or more deficiencies in security systems for monitoring and protecting movable items. One aspect of the present invention includes methods and apparatus to facilitate determining whether an item is missing or not before sounding an alarm. A further aspect of the present invention is an apparatus with improved tamper resistant features to prevent defeating the security system. Still a further aspect of the present invention includes improvements to allow easier attachment, adjustment, and removal of the security device from the item being secured. 
   One embodiment of the present invention includes a security system for a movable item comprising a transmitter and a receiver. The receiver is capable of traveling with the item. The transmitter is capable of transmitting a first signal to the receiver and the transmitter is capable of transmitting a second signal to the receiver. The receiver is capable of receiving the first signal from the transmitter and emitting a first audible sound in response to the first signal. The receiver is also capable of receiving the second signal from the transmitter and emitting a second audible sound in response to the second signal. 
   In a further embodiment, the receiver is capable of producing the first audible sound so that the first audible sound can be heard over a short distance and the receiver is capable of producing the second audible sound so that the second audible sound can be heard over a long distance. 
   A still further embodiment of the present invention may include a circuit capable of turning on the second audible sound in response to at least one of unauthorized detaching of the receiver from the item, unauthorized de-activation of at least one function of the receiver, and unauthorized modification of at least one function of the receiver. 
   Another aspect of the present invention includes a system for use by a supervisor or guardian to provide security for a child. In one embodiment, the system includes a transmitter capable of transmitting at least one of a first signal and a second signal. The transmitter is arranged so that it can be operated by the supervisor. The system also includes a receiver capable of receiving signals from the transmitter and capable of responding to the signals by emitting a first audible sound in response to the first signal or a second audible sound in response to the second signal. A belt may be connected to the receiver for attaching the receiver to the child. The belt may include an electric circuit coupled to the receiver so that the circuit is capable of turning on the second audible sound in response to at least one of: unauthorized detaching of the receiver from the child, cutting through the belt to remove the belt from the child, unauthorized de-activation of at least one function of the receiver, and unauthorized modification of at least one function of the receiver. 
   In one configuration of the present invention, the receiver is capable of producing the first audible sound so that the first audible sound can be heard over a short distance for locating the child when the child is near the supervisor but possibly out of sight of the supervisor. Furthermore, the receiver may be capable of producing the second audible sound so that the second audible sound can be heard over a long distance for at least one of: locating the child, indicating that the child is in danger, and indicating that the supervisor is aware that the child is in danger. 
   It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. In addition, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
   As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out aspects of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
   Further, the purpose of the foregoing abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by the claims, nor is the abstract intended, in any way, to be limiting as to the scope of the invention. 
   The above and still further features and advantages of the present invention will become apparent upon consideration of the following detailed descriptions of specific embodiments thereof, especially when taken in conjunction with the accompanying drawings. 
   Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of an embodiment of the present invention. 
       FIG. 2  is a diagram of an embodiment of the present invention. 
       FIG. 3  is a diagram of an embodiment of the present invention. 
       FIG. 4  is a diagram of an embodiment of the present invention. 
       FIG. 5  is a diagram of an embodiment of the present invention. 
   

   DESCRIPTION 
   The following detailed description is primarily related to applications involving a security system for children, specifically, locating and monitoring children so as to prevent or hinder abductions of children. However, it is to be understood that embodiments of the present invention have applications beyond those of security systems for children. Other applications include security systems for the mentally handicapped, pets or other animals, and inanimate objects such as electronic devices like computers, and particularly laptop computers. 
   Reference is now made to  FIG. 1  where there is shown a block diagram of a security system  100  according to an embodiment of the present invention. System  100  includes a transmitter  110  and a receiving unit  120 . Transmitter  110  is capable of wirelessly transmitting at least two signals using frequencies in the electromagnetic spectrum. Receiving unit  120  is capable of detecting and responding to the signals from transmitter  110 . There are numerous commercially available transmitters that can be used in embodiments of transmitter  110 . Similarly, there are numerous commercially available receivers they can be used in embodiments of receiver unit  120 . 
   For preferred embodiments of the present invention, receiver unit  120  includes a receiver  130 , an attachment mechanism  140 , a search sound generator  150 , a panic sound generator  160 , a tamper detection mechanism  170 , and an arm/disarm lock. Preferably, receiver  130  includes a housing for substantially containing the electronic components of receiver  130 . In a preferred embodiment, the housing for receiver  130  is made of a tough material that is capable of substantially protecting the contents of the housing from physical damage. Some examples of suitable materials for the housing of receiver  130  are aluminum, aluminum alloys, steel, stainless steel, titanium, engineering plastics such as polycarbonate, and composite materials such as fiber-matrix composites. 
   In a preferred embodiment, the housing for receiver  130  includes a compartment for containing a power source such as a compartment for containing batteries for providing electrical power for receiver  130 . Although a variety of designs can be used for the housing for receiver  130 , preferred designs for the housing include those that do not allow easy access to the interior of the housing when receiving unit  120  is in use so that the housing can aid in preventing unauthorized tampering with items within the housing such as the electronic components for receiver  130 , tamper detection mechanism  170 , sound generator  150 , sound generator  160  and the power supply. 
   Attachment mechanism  140  is coupled to receiver  130  and is capable of attaching receiver  130  to the item being monitored. Preferably, attachment mechanism  140  is physically connected with the housing of receiver  130 . The attachment mechanism  140  may be selected from numerous possible attachment mechanisms such as a belt, a strap, a chain, an adhesive, a cable, and others. More specifically, for child monitoring applications, attachment mechanism  140  serves to attach receiver  130  to the child being monitored. Examples of attachment mechanisms that may be used for attachment mechanism  140  for child monitoring applications include a belt, a shoulder harness, a wrist bracelet, an ankle bracelet, a wrist trap, and an ankle strap. In a preferred embodiment, attachment mechanism  140  includes a belt for attachment around the child&#39;s waist. In other embodiments, attachment mechanism  140  may comprise a metal cable such as a multiple strand metal cable that is substantially impossible to sever with a knife. 
   Search sound generator  150  is coupled to receiver  130  so that receiver  130  can activate sound generator  150  so that generator  150  produces a first sound in response to a first signal received by receiver  130  from transmitter  110 . In one embodiment, receiver  130  is coupled to search sound generator  150  so that receiver  130  controls the application of electric power to search sound generator  150  so that sound generator  150  produces the first sound when power is applied and is silent when power to search sound generator  150  is terminated. In a preferred embodiment of the present invention, the electric power for search sound generator  150  is provided by the power source used by receiver  130 . 
   In addition, the search sound generator  160  is coupled to receiver  130  so that receiver  130  can activate panic sound generator  160  so that panic sound generator  160  produces a second sound in response to a second signal received by receiver  130  from transmitter  110 . In one embodiment, receiver  130  is coupled to panic sound generator  160  so that receiver  130  controls the application of electric power to search sound generator  160  so that panic sound generator  160  produces the second sound when power is applied and is silent when power to panic sound generator  160  is terminated. In one embodiment of the present invention, the electric power for search sound generator  160  is provided by the power source used by receiver  130 . 
   Furthermore, in a preferred embodiment of the present invention, search sound generator  150  and panic sound generator  160  are attached to the housing of receiver  130 . More preferably, search sound generator  150  and panic sound generator  160  are attached to an inside wall of the housing of receiver  130 , and the housing has one or more holes to allow sound produced by search sound generator  150  or panic sound generator  160  to more easily propagate to the exterior of the housing. 
   Search sound generator  150  is capable of producing the first sound and panic sound generator  160  is capable of producing the second sound so that the first sound and the second sound are dissimilar. Preferably, the first sound and the second sound are dissimilar in terms of sound intensity. More specifically, the first sound is preferably of a lower intensity than the second sound so that a human can hear the second sound over a longer distance than the first sound can be heard. Optionally, the first sound and the second sound may be dissimilar in terms of other sound characteristics such as the frequency of the sound waves and such as the type of sound. In a preferred embodiment, the first sound is that of a buzzer and the second sound is that of a siren. 
   Tamper detection mechanism  170  serves to substantially prevent unauthorized tampering activities directed toward deactivating or neutralizing the function of receiving unit  120  or unauthorized removal of receiving unit  120  from the child or other item that is being monitored. The tamper detection mechanism  170  may include one or more capabilities for detecting the tampering activity. One optional capability of mechanism  170  includes an electrical circuit coupled to the power supply that provides power to panic sound generator  160 . The electrical circuit is coupled to the power supply so that if the circuit is opened such as by disconnecting attachment mechanism  140  from the child or other object that is being monitored, then panic sound generator  160  is activated to generate the second sound. 
   Arm/disarm lock  180  is coupled to receiver  130  and particularly the power supply for receiver  130 , search sound generator  150 , and panic sound generator  160 . Specifically, lock  180  includes a lockable switch for turning the power on and turning the power off to allow operation or non-operation of receiver unit  120 . In other words, lock  180  is a manual switch for controlling the power availability for at least one of receiver  130 , search sound generator  150 , and panic sound generator  160 . 
   Preferred embodiments of the present invention are configured so that lock  180  controls power availability for all of the power consuming components of receiving unit  120 . 
   Reference is now made to  FIG. 2  where there is shown a more detailed view of an embodiment of a receiving unit  122  according to the teaching of the present invention.  FIG. 2  shows a perspective view of receiving unit  122 . Receiving unit  122  includes a housing  132  for a receiver substantially the same as that described for the embodiment shown in  FIG. 1  (receiver not shown in  FIG. 2 ). Housing  132  is substantially the same as that described for the embodiment shown in  FIG. 1 . Preferably, the receiver comprises a printed circuit board with appropriate electronic components and circuits for operating as a receiver and the printed circuit court is held in housing  132 . 
   Also shown in  FIG. 2  is a belt  142  for attaching the receiver to a child or other item that is being monitored. Preferably, one end of belt  142  is physically connected with housing  132 . In a still more preferred embodiment, belt  142  comprises a web structure of a high-strength material such as nylon and such as Kevlar(R). For child monitoring applications, it is preferable for belt  132  to be of a length suitable for attachment around the child&#39;s waist. 
   A variety of known techniques may be used for connecting the ends of belt  142 . A preferred embodiment of the present invention includes hook and loop structures such as Velcro® for connecting the ends of belt  142 .  FIG. 2  shows one end of belt  142  having a hook structure  144  which attaches to a corresponding loop structure connected with the rear side of housing  132  (the corresponding loop structure not shown in  FIG. 2 . Optionally, the embodiments of the present invention may have the hook structure and loop structure locations reversed. In a preferred embodiment of the present invention, hook structure  144  or the corresponding loop structure is an elongated section of material with the long dimension substantially aligned with the length of the belt so that the diameter of the belt, when fastened, can be adjusted to provide a snug fit around the child or other item being monitored. 
     FIG. 2  also shows the location of a search sound generator  152 . Search sound generator  152  is located substantially within housing  132 . Preferably, housing  132  has a hole or a plurality of holes adjacent to search sound generator  152  to facilitate the propagation of sound from search sound generator  152 . 
   In addition,  FIG. 2  shows the location of panic sound generator  162 . The panic sound generator  162  is located substantially within housing  132 . Preferably, housing  132  has a hole or a plurality of holes adjacent to panic sound generator  162  to facilitate the propagation of sound from panic sound generator  162 . 
   Receiving unit  120  shown in  FIG. 2  includes an on/off switch  182 . Switch  182  includes a lock that requires a key for switching the operation of receiving unit  122  on or off. Specifically, switch  182  makes power available or unavailable to at least one of the receiver, search sound generator  152 , and panic sound generator  162 . The configuration requiring a key for on/off control is included so as to substantially prevent unauthorized shutoff or unauthorized activation of receiving unit  122 . In other words, the lock and key configuration is a characteristic of the embodiment of the present invention shown in  FIG. 2  for preventing unauthorized tampering with the operation of receiving unit  122 . 
   The embodiment shown in  FIG. 2  also includes a tamper detection mechanism that comprises an electrical interlock circuit integrated with belt  142  and coupled to at least one of the receiver in housing  132 , the power supply for panic sound generator  162 , and panic sound generator  162 . The interlock circuit includes an electrically conducting wire  172  substantially contacting belt  142  through the length of belt  142 . Preferably, wire  172  is threaded through the interior of belt  142  through at least a portion of the length of belt  142 .  FIG. 2  shows wire  172  as a dashed line to indicate that wire  172  is located in the interior of belt  142 . For embodiments of belt  142  that comprise a web material such as nylon webbing, it is preferable to arrange wire  172  so that wire  172  is interweaved through the webbing of belt  142 . Optionally, materials other than nylon may be used for belt  142 . In one embodiment of the present invention, wire  172  comprises a 30 AWG wire. 
   Preferably, the interlock circuit also includes an electrode  174  that is connected with one end of wire  172 .  FIG. 2  shows electrode  174  on the surface of one end of belt  142 . In one embodiment of the present invention, electrode  174  is a substantially flexible electrical conductor. A second electrode (not shown in  FIG. 2 ) is also included for making contact with electrode  174 . The second electrode is connected with the rear of housing  132  and is arranged so as to be capable of electrically contacting electrode  174  and thus electrically closing the interlock circuit of the tamper detection mechanism. Wire  172 , electrode  174 , and the second electrode are included in the interlock circuit so that when receiving unit  122  is armed, the panic sound generator is activated if the interlock circuit is broken by at least one of severing wire  172  and breaking the electrical contact between electrode  174  and the second electrode. This means that cutting through the belt will trigger the alarm or disconnecting the belt will trigger the alarm. 
   For the embodiment shown in  FIG. 2 , electrode  174  and the second electrode are arranged so that by fastening belt  142  by contacting hook material  144  with the corresponding loop material on the back of housing  132  causes electrode  174  and the second electrode to make electrical contact for completing the interlock circuit. This means that detaching hook material  144  from the corresponding loop material will cause activation of the panic sound generator when receiving unit  122  is armed. It also means that receiving unit  122  must be turned OFF prior to being removed from the child or other item being monitored. Including the arm/disarm control switch will also help prevent accidentally leaving receiving unit  122  ON and prevent unintentionally draining the battery. 
   In a preferred embodiment, electrode  174  is an elongated substantially flexible electrical conductor having a width of about ½ inch (1.2 mm) secured to the middle of a band of Velcro® or other types of hook and loop structures for fastening and unfastening. In addition, the second electrode is preferably a 14 AWG elongated electrical conductor attached to the rear side of housing  142  adjacent to a corresponding band of Velcro® or other types of hook and loop structures for fastening belt  142 . 
   The length of electrode  174  and the length of the second electrode may be selected based on the desired amount of adjustment capability for belt  142  around the child or other item being monitored. A close-fitting attachment of receiving unit  122  to the child or other item being monitored is preferable so as to hinder having receiving unit  122  removed from the child or other item being monitored without triggering the tamper detection mechanism. In other words, it is preferable for receiving unit  122  to have a sufficiently snug fit so as to prevent an abductor from removing receiving unit  120  from the child or other item being monitored. In a preferred embodiment, electrode  174  has a length of about 3 inches (7.5 cm) and the second electrode has a length of about 3 inches (7.5 cm). It is to be understood that the length selection is an option and it is not necessary for the length of electrode  174  to equal the length of the second electrode. 
   Embodiments of the present invention that use a hook and loop closure mechanism such as Velcro®, preferably have at least one of the length of the materials of hook structure and the length of the materials of loop structure elongated so as to allow the diameter of the belt to be adjustable to provide a snug fit for the belt around the child or other item being monitored. 
   It is to be understood that other attachments methods may be used in embodiments of the present invention. Alternative embodiments may include a harness for attachment around the shoulders of the person being monitored. Or the embodiment may include a metal cable for attachment around the waist of a person or child being monitored. The cable may be fastened with a lock such as a cable lock like that used on some bicycle locks. An interlock circuit for tamper detection may also be used with other types of fastening mechanisms. 
   In a preferred embodiment, receiving unit  122  includes an indicator for showing information about the status of receiving unit  122 . For example, receiving unit  122  shown in  FIG. 2  includes a light emitting diode  184  for indicating when receiving unit  122  is armed or disarm. In this embodiment, diode  184  is on when receiving unit  122  is armed and diode  184  is off when receiving unit  122  is disarmed. Receiving unit  122  may also be configured to indicate other information using diode  184 . In a preferred embodiment, diode  184  is configured to provide either a bright light or a dim light to indicate the status of the battery used for powering receiving unit  122 . In one configuration, the dim light may be used to indicate that receiving unit  122  is on, and the bright light may be used to indicate that the power available from the batteries is low. In other words, the bright light would be an indicator that the battery should be replaced or recharged. Of course, it is to be understood that additional status indicators can be used and other types of status indicators can be used; embodiments of the present invention are not limited to the use of light emitting diodes as indicators. 
   Reference is now made to  FIG. 3  where there is shown a perspective view of a portion of the receiving unit described in  FIG. 2 . Specifically,  FIG. 3  shows a view of the rear of housing  132  and a portion of belt  142 .  FIG. 3  also shows wire  172 , second electrode  175  attached to the rear side of housing  132 , and loop structure  145  for attachment to the corresponding hook structure  144  described for  FIG. 2  (hook structure  144  not shown in  FIG. 3 ). The loop structure  145  is attached to the rear side of housing  132 .  FIG. 3  also shows an optional screw  134  for access to a battery compartment in housing  132 . As an option for some embodiments of the present invention, screw  134  may be used for attaching a cover for the battery compartment of housing  142 . Of course, the screw may also be used for gaining access to the interior of housing  142  for activities such as adjustment and maintenance of the receiver and tamper detection mechanism contained in housing  132 . 
   Reference is now made to  FIG. 4  where there is shown a perspective view of a transmitter  112  according to one embodiment of the present invention. Transmitter  112  is capable of wirelessly transmitting signals to a receiving unit such as the receiving unit described in  FIG. 1 ,  FIG. 2 , and  FIG. 3  (receiving unit not shown in  FIG. 4 ). Transmitter  112  includes a housing  114  for substantially enclosing the electronic components of the transmitter. Preferably, housing  114  is substantially rigid and may be made from materials such as metal, metal alloys, and plastic. 
   Transmitter  112  has a search button  116  for activating a search sound generator. 
   More specifically, the search button is used to activate the search sound which may be a sound such as that of a 400 Hz buzzer and may have a sound intensity of about 70 db. In a preferred embodiment, the search signal is generated as long as button  116  is pressed. The search sound is, preferably, selected so as to be very directional so that it is easy to determine the location of the child or other object being monitored. In one embodiment of the present invention, the approximate arrange for the search sound may be about 100 feet (about 30 m). 
   The transmitter  112  also includes a panic button  118  for activating a panic sound generator. In a preferred embodiment, the panic sound generator is capable of producing a sound having an intensity of about 120 db such as a sound produced by a loud siren. Preferably, panic button  118  initiates a latched signal that will remain on until the panic sound generator is turned off. In one embodiment, the panic sound generator is also connected with search button  116  so that the panic sound generator is turned off after search button  116  is depressed. Alternatively, the panic sound generator may be connected to the arm/disarm switch so that panic sound generator is activated only after disarming receiving unit  122 . 
   Preferably, transmitter  112  is configured so that it becomes active when either search button  116  or panic button  118  is pressed. In one embodiment, transmitter  112  is capable of wirelessly transmitting signals in the range 300 MHz to 375 MHz for a distance up to about 150 feet (45 m). Optionally, transmitter  112  may include a trim capacitor for tuning to the receiver frequency of receiving unit  122 . The frequency may be set, for example, at approximately 318 MHz or any other frequency in the range of the transmitter that can be detected by the receiver. In one embodiment, transmitter  112  is capable transmitting signals using carrier waves having frequencies in the range of about 300 MHz to 440 MHz and all subranges subsumed therein. 
   It is to be understood that other embodiments of the present invention may use frequencies other than those in the range of about 300 MHz to 440 MHz. Furthermore, embodiments of the present invention may a larger operation distance than that for the embodiment given above. As another embodiment, a frequency of about 900 MHz may be used and the operating distance for transmitting signals to the receiver may be about 1000 feet. 
   Optionally, transmitter  112  may also include a status indicator such as a light emitting diode  119  shown in  FIG. 4 . The status indicator may be used for providing information such as the active or inactive state of transmitter  112 . For instance, the indicator may be used to indicate that the search button  116  or panic button  118  has been or is being pressed. 
   In one embodiment, transmitter  112  includes a 10-position DIP switch capable of providing  1024  different possible codes. These signals feed to an encoder which will output a series signal of the DIP switch settings, along with the appropriate code for activating the search sound generator by depressing search button  116  or for activating the panic sound generator by depressing panic button  118 . The signal is then sent into an LC oscillator set to the transmission frequency. A radio frequency transistor and loop antenna included in transmitter  112  then radiate the encoded signal on a carrier wave such as a 318 MHz carrier wave. 
   In a preferred embodiment, receiver unit  122  uses a MIC001 receiver integrated circuit which is a commercially available circuit that includes a complete superheterodyne receiver intended for use in the UHF frequency bands from 300 MHz to 440 MHz. Alternatively, embodiments of the present invention may use integrated circuits that are substantially equivalent to the MIC001 integrated circuit. The integrated circuit incorporates complete UHF down conversion and data demodulation functions. Once the carrier signal has been stripped, the signal is feed to the decoder circuit which may include a 10-position DIP switch and decoder circuit. The decoder compares the incoming signal to the DIP-switch setting on the receiver. If the signal matches the DIP-switch settings, the appropriate output line will activate the panic sound generator or the search sound generator, depending on whether the search button or the panic button was depressed. 
   Reference is now made to  FIG. 5  where there is shown a flow diagram for a method  200  for use by a guardian for monitoring a child according to an embodiment of the present invention. The method is carried out by a guardian using embodiments of the present invention. Step  210  is the first step in the method and represents the start of the method. Step  220  follows step  210  and involves making the decision as to whether the child is lost or not lost. If the child is not lost, then return to step  210 . 
   If the child is lost then the next step is step  230 ; step  230  includes activating a search sound for use in locating the child. Step  235  follows step  230 . The step  235  is a decision step where the guardian determines whether the search sound is audible. If the search sound is not audible to the guardian then the next step after step  235  is step  240  which includes activating the panic sound. If the search sound is audible to the guardian then the next step after step  235  is step  245  which involves searching for the source of the search sound. Step  250  follows step  245 . The step  250  is a decision step; if the child is found then the next step is step  255  which involves shutting off the search sound; if the child is not found, then the next step is step  260  which involves activating the panic sound. 
   Clearly, embodiments of the present invention can be used in numerous situations in which security is required. One example of a specific application for embodiments of the present invention includes providing security for children. Indeed, embodiments of the present invention can be used to quickly locate a small child or other item being monitored when missing from a supervisor or guardian in environments such as that of a store, a mall, and a home. Embodiments of the present invention are particularly suited for reducing the instances of sounding false alarms because of the capability of providing searching assistance for the guardian in the event the child is merely out of view and not in danger. The search assistance capability of embodiments of the present invention can help the guardian locate the child substantially without alarming other people who may be in the vicinity. This is also advantageous in that the guardian can search for the child substantially without scaring or alarming the child. This means that if the child is found using the search sound capabilities, then there is no need to disturb others in the area and no need to frighten the child. 
   In addition, embodiments of the present invention can be produced that are very simple to operate and do not require complex equipment for implementation. Furthermore, embodiments of the present invention offer flexibility in attaching the monitoring device to the child or other item being monitored. In other words, embodiments of the present invention are adjustable so as to more easily accommodate size variations for the child or other item being monitored. 
   Indeed, embodiments of the present invention can be easily put on a small child such as a child less than about 10 years old and can be used on still smaller children such as children in the age range of 1–5 years old. The belt of a receiving unit according to embodiments of the present invention can be attached around the child&#39;s waist using a fastening system such as Velcro®. In addition, the interlock system in some embodiments of the present invention makes it extremely difficult to remove the receiving unit from the child without alarming the guardian. Still further, for applications involving very small children, the fastening mechanism and embodiments of the present invention make it very difficult for the child to remove the receiving unit. 
   It is to be understood that although embodiments of the present invention are particularly suitable for use with children, embodiments of the present invention can also be used to monitor older children and adults; in other words, a person of any age can be monitored with embodiments of the present invention. Indeed, embodiments of the present invention are suitable for use in monitoring and providing security for mentally handicapped individuals or individuals that suffer from illnesses such as Alzheimer&#39;s disease. 
   While there have been described and illustrated specific embodiments of the invention, it will be clear that variations in the details of the embodiments specifically illustrated and described may be made without departing from the true spirit and scope of the invention as defined in the appended claims and their legal equivalents. 
   In the foregoing specification, the invention has been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. 
   Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. 
   As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “at least one of,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited only to those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).