Patent Publication Number: US-7719418-B2

Title: System and method for locating objects

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention pertains generally to electronic transmitting devices. More particularly, the present invention pertains to systems and method for tracking objects. The present invention, in a preferred embodiment, is particularly but not exclusively, useful as an electronic tracking system and method to indicate to a user the presence of personal objects of interest. 
   2. Description of the Prior Art 
   As people move about in their daily routine or while traveling, they take a number of items with them that could potentially become lost or misplaced. Items including mobile phone, car keys, camera, briefcase, backpack, purse, PDA, and laptop computer may potentially disappear from their owner sometimes requiring time consuming searching to recover. 
   Numerous systems and methods have been proposed for monitoring, tracking, and locating persons, pets or objects carrying an electronic tracking device. Some have been presented as an electronic inventory for businesses tracking items. Others have been described as an electronic leash for pets or children at a day care center, or an alert system for wandering Alzheimer&#39;s patients or autistic children. While most prior art solutions are suitable for their intended purposes, most are also overly complicated and expensive solutions for wide commercial application. A relatively recent example of one such system is disclosed in Crabtree, U.S. Pat. No. 7,148,801, Article Locator System. Crabtree is directed to a system wherein a transceiver is attached to a person, animal, or item to be tracked also with a handheld locator device to send radio signals to the various transceiver devices of the system. As signals are transmitted and received from the devices, the system employs an antenna array to sample the signal at different points in space. With various samples from the antenna array, the system can employ different methods to calculate the bearing and range of the object including processing information from phase and time delays 
   Another example of a prior art system is disclosed in Rabanne, U.S. Pat. No. 6,304,186. Rabanne similarly employs a plurality of child units each having a transceiver and a parent unit for determining if an object is within a preselected range. Rabanne further has separate communication devices for locating and controlling the plurality of child units wherein one such separate communication device is a GPS device for determining relative distance from a child unit to a parent unit. 
   These and other examples are particularly complicated while employing GPS or multi signal path calculations particularly if the items to be tracked are relatively close to user. Numerous other examples exist and many are limited by battery life as well as cost to implement. As advancements in electronic technology have appeared, other wireless communication proposals have emerged. For example, Bluetooth radio standard and communication protocol has gained popularity for its range of applications as transceiver microchips can presently be designed for low-cost and low power consumption. Moreover, software advancements specifically designed for low power applications, for example Zigbee, has prompted consumer electronic solutions refocusing on cost effective wider availability. 
   In light of the above, it is an object of the present invention to provide a System and Method for Locating Objects that is simplified over prior art solutions. It is further an object of the present invention to provide a system and method for tracking objects that is optimized for low-power and lower cost. It is yet further an object of the present invention to provide an object tracking system that can selectively track a significant number of objects up to about 250. It is still further an object of the present invention to provide an object tracking system and method that can be programmed via a computer device. Additionally, a further object of the present invention is to provide a System and Method for Locating Objects that is easy to implement, simple to use, and comparatively 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention specifically addresses and alleviates the above mentioned deficiencies associated with the prior art. More particularly, the present invention comprises a system for locating objects comprising: a Coordinator unit comprising a first antenna, a first power source, a first integrated transceiver microprocessor, the first power source electrically connected to the first integrated transceiver microprocessor, and the antenna coupled to the first integrated transceiver microprocessor; an Identification Tag comprising a second antenna, a second power source, a second integrated transceiver microprocessor, the second power source electrically connected to the second integrated transceiver microprocessor, and the antenna coupled to the second integrated transceiver microprocessor; wherein the first and second integrated transceiver microprocessors communicate with each other according to predetermined timing cycles optimized for power consumption; and wherein the Coordinator unit further comprises an LCD display conveying information to a user, the information including a signal strength corresponding to a transmitted and a received power, and wherein the signal strength is a relative measure of distance between the Coordinator and the Identification Tag. 
   In a preferred embodiment of the present invention, the Coordinator unit further comprises a first sound device coupled to the first processor, the sound device programmed to audibly indicate when the Coordinator unit loses (or regains) communications with the Identification Tag; and wherein the first sound device comprises a simple beep generator, able to generate a plurality of combinations of short and/or prolonged beeps, wherein each of said plurality of combinations corresponds to a condition of the Identification Tag unit; and wherein the Identification Tag unit further comprises a second sound device coupled to the second integrated transceiver microprocessor, the second sound device programmed to audibly indicate when the Identification Tag receives an appropriate polling command from the Coordinator unit; and wherein the Coordinator unit further comprises a beacon coupled to the first integrated transceiver microprocessor, the beacon programmed to visually indicate when the Coordinator unit loses (or regains) communications with the Identification Tag unit; and wherein the Identification Tag unit further comprises a second beacon device coupled to the second integrated transceiver microprocessor, the second beacon device programmed to visually indicate when the Identification Tag receives an appropriate polling command from the Coordinator unit; and wherein the Coordinator unit further comprises a first user interface wherein the user can initiate a communication between the Coordinator and the Identification Tag. 
   Additionally in a preferred embodiment, the LCD display information further includes a Coordinator battery voltage, an Identification Tag battery voltage, an Identification Tag common name, and an indication that the Identification Tag is not responding to a communication; and wherein the Coordinator further comprises a first motion sensor able to detect when the Coordinator is physically moving, and wherein the Identification Tag further comprises a second motion sensor able to detect when the Identification Tag is physically moving; and wherein a communication between the Coordinator and the Identification Tag comprises a plurality of bytes of information, and wherein the bytes of information comprise a transmit power of the Identification Tag, and movement of the Identification Tag based on the second motion sensor, the movement available as information on the LCD display; and wherein the transmit power of the Identification Tag in successive communication cycles is compared by the first integrated transceiver microprocessor, and wherein information from the first and second motion sensors are further compared by the first integrated transceiver microprocessor to determine if the Identification Tag is moving toward or moving away; and wherein the transmit power of the Identification Tag is compared to the signal strength and wherein the transmit power of a subsequent communication cycle is optimized based on the transmit power of the Identification Tag and the signal strength. 
   The present invention may be further characterized wherein the Identification Tag unit further comprises a preprogrammed interval corresponding to the second integrated transceiver microprocessor enabling the Identification Tag unit to wake up and listen for communication from the Coordinator unit, the preprogrammed interval optimized for power consumption. 
   The invention is further characterized in that the system further comprises a plurality of second and subsequent Identification Tag units each communicating with the Coordinator unit according to predetermined timing cycles optimized for power consumption; and wherein the LCD display conveying the information further includes a signal strength corresponding to a relative measure of distance between the Coordinator and each of the second and subsequent Identification Tags; and wherein the plurality of second and subsequent Identification Tags can be selectively tracked by the Coordinator or otherwise remain inactive; and wherein the Coordinator unit further comprises a toggle switch configured to selectively scroll-up or scroll-down a list of items, the toggle switch further having a push operation to select an item, the Coordinator unit further comprising a separate switch for un-selecting an item. 
   The invention is further characterized in that the Identification Tag further comprises: a selectively attachable clip appropriate for fastening the Identification Tag to a pocket or a belt; a key chain clip suitable for attaching the Identification Tag to a key chain; and a carrying strap suitable for wearing around a user&#39;s neck or wrist; and wherein the Identification Tag unit is manufactured with a unique electronic address different from all others manufactured. 
   Yet further, the LCD display conveying information further includes a motion indicator, the motion indicator comprising symbols to indicate relative movement between the Coordinator and the Identification Tag. Additionally, a second Coordinator may be added to the invention wherein the first and second Coordinators communicate with each other having a signal strength associated therewith, the signal strength a measure of the relative distance between the first and second Coordinators; and wherein the Coordinator and the Identification Tag are comprised of durable shock resistant material; and wherein the Coordinator and the Identification Tag each comprise a battery compartment cover; and wherein the Coordinator comprises a battery voltage, the battery voltage continually monitored and wherein an indication is provided when the battery voltage drops below a minimum operating value; and wherein the Identification Tag is integrated directly into an object to be tracked, wherein the object has material suitable for Identification Tag integration; and wherein the Coordinator further comprising a USB port and wherein the first power source can be recharged via the USB port; and wherein the Coordinator is a cellular device. 
   In another aspect the invention is a method for tracking an object comprising: providing a Coordinator unit having a first transceiver chip and an LCD display attaching an Identification Tag unit to the object to be tracked, the Identification Tag having a second transceiver chip; communicating wirelessly between the Coordinator and the Identification Tag; optimizing power consumption for communication according to predetermined timing cycles; and conveying information to a user, the information including a signal strength corresponding to a transmitted and a received power, and wherein the signal strength is a relative measure of distance between the Coordinator and the Identification Tag. 
   In a preferred embodiment, the method of the invention further comprises programming the Coordinator to audibly indicate when the Coordinator unit loses (or regains) communications with the Identification Tag, wherein the programming the Coordinator to audibly to indicate when the Coordinator unit loses (or regains) communications with the Identification Tag comprises a simple beep generator, able to generate a plurality of combinations of short and/or prolonged beeps, wherein each of said plurality of combinations corresponds to a condition of the Identification Tag unit. 
   The method of the invention may also include: polling the Identification Tag to initiate a communication; programming the Identification Tag to audibly indicate when the Identification Tag receives an appropriate polling command from the Coordinator unit; programming the Coordinator to visually indicate when the Coordinator unit loses (or regains) communications with the Identification Tag unit; polling the Identification Tag to initiate a communication; and programming the Identification Tag to visually indicate when the Identification Tag receives an appropriate polling command from the Coordinator unit; displaying information on the Coordinator unit, the information including a Coordinator battery voltage, an Identification Tag battery voltage, an Identification Tag name, and an indication that the Identification Tag is not responding to a communication; detecting when the Coordinator is physically moving; detecting when the Identification Tag is physically moving; processing the detection of the moving of the Coordinator and the Identification Tag along with a transmit power and a received power of successive communication cycles to determine if the Identification Tag is moving toward or moving away; comparing a transmit power of the Identification Tag to the signal strength and wherein the transmit power of the subsequent communication cycle is optimized based on said transmit power of the Identification Tag and said signal strength; and manufacturing the Identification Tag unit with a unique electronic address different from all others manufactured. 
   Additionally, the method comprises providing a plurality of second and subsequent Identification Tag units each communicating with the Coordinator unit according to predetermined timing cycles optimized for power consumption; and wherein the conveying the information further includes a signal strength corresponding to a relative measure of distance between the Coordinator and each of the second and subsequent Identification Tags; and wherein the method further comprises selectively tracking the plurality of second and subsequent Identification Tags using the Coordinator. 
   Still further, the method comprises: providing for the Coordinator a toggle switch configured to selectively scroll-up or scroll-down a list of items, the toggle switch further having a push operation to select an item; providing the Coordinator a separate switch for un-selecting an item. Furthermore, the method includes providing a cellular device configured for use as a coordinator. The method also includes preprogramming an interval for the Identification Tag unit to wake up and listen for communication from the Coordinator unit, the interval optimized for power consumption. 
   Yet still, method comprises: providing a USB port to the Coordinator; uploading selectable features to the Coordinator from a computer device via a USB cable; providing a clip for the Identification Tag appropriate for fastening the Identification Tag to a pocket or a belt; providing a second Coordinator; communicating between the first and second Coordinator having a signal strength associated therewith, the signal strength a measure of the relative distance between the first and second Coordinators; manufacturing the Coordinator and the Identification Tag of durable shock resistant material; and providing a battery compartment cover for each of the Coordinator and the Identification Tag. 
   Yet still further, the method is characterized wherein the Coordinator comprises a battery voltage, and the method further comprises continuously monitoring the battery voltage and providing an indication when the battery voltage drops below a minimum operating value; and wherein the method further comprises integrating the Identification Tag directly into an object to be tracked, wherein the object has material suitable for Identification Tag integration; and wherein the Coordinator further comprises a power supply and a USB port, the method further comprising recharging the power supply via the USB port. 
   Additionally, the method is characterized wherein the conveying information further includes a motion indicator, the motion indicator indicating relative movement between the Coordinator and the Identification Tag using symbols. 
   In another aspect the invention is a method of associating a plurality of Identification Tags to a Coordinator, the method comprising: providing each Identification Tag with a unique MAC address; transmitting from a first Identification Tag to the Coordinator to start the associating along with a first unique MAC address for the first Identification Tag; receiving the first unique MAC address to the Coordinator; comparing the first unique MAC address to a list of previously associated MAC addresses; adding the first unique MAC address to the list of previously associated MAC addresses, in the event that the first unique MAC address is not currently on the list; entering a common name of an object associated with the first Identification Tag; and repeating the method for second and subsequent Identification Tags. 
   Further the method of associating a plurality of Identification Tags to a Coordinator is characterized wherein subsequent to the receiving the first unique MAC address to the Coordinator, the method further comprised transmitting to the first Identification Tag that the Coordinator is “associating.” Also this method can be further characterized wherein if the first unique MAC address is currently in the list of previously associated unique MAC addresses, the method further comprises transmitting to the first Identification Tag “previously associated;” and wherein the method further comprises transmitting “associated” to the first Identification Tag after the entering the common name of the object associated with the first Identification Tag. 
   These, as well as other advantages of the present invention, will be more apparent from the following description and drawings. It is understood that changes in the specific structure shown and described may be made within the scope of the claims, without departing from the spirit of the invention. 
   While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 USC 112, are not to be construed as necessarily limited in any way by the construction of “means” or “steps” limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 USC 112 are to be accorded full statutory equivalents under 35 USC 112. The invention can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
       FIG. 1  is a schematical diagram depicting objects leaving or coming into a person&#39;s proximity that may be selectively tracked according to the present invention; 
       FIGS. 2A ,  2 B and  2 C are frontal and side views illustrative of a particular embodiment of a Coordinator of the present invention; 
       FIGS. 3A and 3B  are isometric and side view illustrations of a particular embodiment of a Transponder Identification Tag of the present invention; 
       FIG. 4  is a block diagram of a Coordinator; 
       FIG. 5  is a block diagram of an Identification Tag; 
       FIG. 6  is a flowchart depicting the workflow of a particular Coordinator&#39;s main programmed processes; 
       FIG. 7  is a flowchart depicting the workflow of a particular Identification Tag&#39;s main programmed processes; 
       FIG. 8  is a flowchart depicting the procedure of associating an ID Tag with a Coordinator; and 
       FIG. 9  is a schematical illustration depicting the connection of a Coordinator to a personal computer using a USB cable. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A. Overview 
   Referring initially to  FIG. 1 , an embodiment of the present invention is illustrated having a two-way radio transponder system, generally designated  10 , that is used to notify user  11  when objects being tracked  13 ,  14 ,  15  come into user&#39;s  11  approximate immediate proximity or leave the immediate proximity. Coordinator  20  is a locator device and is more closely viewed in  FIGS. 2A ,  2 B and  2 C. 
     FIG. 1  generally depicts the present invention wherein user  11  is in possession of a Coordinator  20 . Objects of interest  13  through  15  each have an Identification Tag  30   a  through  30   c  ( FIGS. 3A and 3B ) affixed to them. Additionally, each Identification Tag (hereinafter “ID Tag”)  30   a - 30   c  has been manufactured with a unique electronic address that is then assigned a common name by the user  11  programmed into Coordinator  20 . Common names may describe objects to be kept track of, such as “camera”  13 , “car keys”  14 , “briefcase”  15  as illustrated in this example. 
   Further to  FIG. 1  and  FIG. 2 , as any of the objects  13 - 15  come into range of the user  11 , the user  11  is alerted. User  11  may select that a particular object  13 - 15  be kept track of, or ignore it. As objects that are being tracked begin to move away from user  11 , the user  11  is alerted either visibly or audibly. Visual indication, in various embodiments may include a light-emitting diode  17  or, a visual display  16  showing the common name  16   d  of the object of interest and an indication  16   b  of the relative motion of that object. In a particular embodiment, motion sensors  56  ( FIG. 5 ) inside ID tags  30   a - 30   c  help to determine if user  11  is moving away from an object being tracked, or if the object is moving way from the user  11 . If for example, an object  15  is being carried away by someone else, or if the object  15  is arriving on a baggage conveyor belt, motion is detected together with a change in radio signal strength received by the Coordinator  20  in successive communication cycles. 
   More specifically referring to  FIG. 2A , user  11  may scroll  22  through a display  16  of object common names  16   d , for example, seeking the location of an object of interest. If object  14  is the object of interest, user  11  will scroll  22  to; “car keys”  14  on display  16   d  and press a button  22  which will send a signal to a “car keys” ID tag  30   b  causing that ID tag  30   b  to beep  33  ( FIG. 3A ), and flash an indicator light  32 . In the specific embodiment illustrated, scroll switch  22  is also a push button  22  and essentially a 3-way switch comprising up, down and push selections. 
   As previously stated, when any of the objects  13 - 15  come into radio transmission receiving range of the Coordinator  20 , the user  11  is alerted by both an audible beep sound  18 , and a visual display  16  of that common name  16   d  along with an indication  16   b  of the relative motion of that object. User  11  may select  22  that object to be kept track of, or to ignore it for the time-being. As objects that are currently being tracked begin to move away from user  20 , the user is alerted  16   b . In a particular embodiment of the present invention, motion sensors  56  inside the ID tag  30  help to differentiate between the user  11  moving away from an object being tracked, or if the object is moving away from the user  11 . Additionally, objects  13 - 15  may be in the proximate range of the Coordinator  20  but may not be visible to user  11 . To assist in locating a particular object  13 - 15 , the user  11  may scroll  22  thru the display  16   d  of object common names  16   d , and, for example, select “car keys”  14  and press a “call” button  22  on Coordinator  20  which will send a signal to the ID Tag  30   b  causing that ID tag  30   b  to emit an audible beep  33  and flash a visual indicator light  32 . 
   Also referring to  FIG. 2A , Coordinator  20  contains a list  16   d  of all Transponder ID Tags  30  that user  11  has programmed into Coordinator  20 .  FIGS. 3A and 3B  illustrate isometric and side views of a Transponder ID Tag  30  that could be any one of ID Tags  30   a - 30   c  of an embodiment of the present invention. For each ID Tag  30  that is currently being tracked, the Coordinator  20  transmits a modulated radio frequency signal which includes the unique identification code of that ID Tag  30  together with a “Hello” command  70  ( FIG. 7 ). Each ID Tag  30  periodically wakes up from power-saving sleep mode to listen for a “Hello” addressed to it. Importantly, Coordinator  20  transmits to the objects being tracked at predetermined timing intervals optimized for cost of system  10  and power consumption. Additionally, the radio circuits contained within ID Tags  30  are smaller in size and lower in cost making system  10  a viable solution to tracking objects than previously conceived. The ID Tag  30  which corresponds to the transmitted identification code then responds with a packet of information which the Coordinator  20  records in RAM memory within the microprocessor circuitry  41 . This packet of information transmitted back from the ID Tag  30  to the Coordinator  20  may contain, in a particular invention embodiment, the signal strength  73  of the received transmission, the status of the motion sensor  53  and other sensors  72 , and its battery level  52 . As the Coordinator  20  polls each ID Tag  30 , it is able to determine from changes in the previous signal strength  73  motion sensor  53  indicator, whether the object being tracked is moving away from or coming toward the user  11 , with the purpose of notifying the user  11  when said object is in proximity of the user  11 . In this manner, the user  11  may know if some object they have in their possession is about to leave their immediate proximity or is no longer in their immediate proximity. 
   B. The Transponder Identification Tag 
     FIG. 3A  illustrates one embodiment of the Transponder ID Tag. The ID Tag  30  is very small in size and may be attached to any variety of objects that one may wish to track. A carrying strap  38  may be attached to the eyelet  34  such that the ID Tag  30  may be worn around the wrist or as a necklace. Belt-clip  35  permits the ID Tag  30  to be easily attached to objects. A double-sided tape foam pad  36  is provided as an option such that the ID Tag  30  may be adhered to a flat surface of an object to be tracked. The enclosure of the ID Tag  30  may be made of a durable and water-resistant material, for example such as plastic, and is built to withstand a reasonable amount of shock and impact. 
   The ID Tag  30  further may be powered by a small watch-type battery  52 . Owing to the extremely low power consumption of the integrated radio transceiver and microprocessor technology  41  and  51  respectively, a battery life of several months to more than a year can be expected even under continuous use. The battery voltage  52  of the ID Tag  30  is constantly monitored by Coordinator  20 , and as the ID Tag  30  battery voltage  52  drops below a minimum good operating value, the user  11  is alerted that the battery  52  should be replaced, accessible from the battery compartment cover  37 . 
   In a particular embodiment, the ID Tag  30  electronic circuits are built into a self-contained plastic housing. In another embodiment, it may be desirable to integrate the ID Tags  30  electronic circuits directly into the device to be tracked, such as in the handle of a briefcase or suitcase, or woven into the fabric of a dog collar. Additionally, how and where the ID Tag  30  is integrated into objects to be tracked is not limited by this embodiment. 
   Transponder ID Tags  30  have a primary function of responding to queries from an associated Coordinator  20 , and alert user  11  when an object being tracked is either leaving the immediate proximity or entering into the immediate proximity of the user  11 . In a particular embodiment, the ID Tag  30  contains a pushbutton  31  that may be used either to: 1) associate itself with a particular Coordinator  20 , or 2) send a “call” signal to the associated Coordinator  20 . 
   Further in a particular embodiment ID Tag  30  contains enunciator  33 , or alternatively sound generator  33 , which, upon receipt of a command from the Coordinator  20  to beep, emits an audible signal tone. Several types of signal tones may be emitted by the ID Tag  30  based on the intended purpose. In a separate embodiment, ID Tag  30  may be pre-preprogrammed with specific mode of operation instructions whereby in the event that an ID Tag  30  does not receive a “Hello” signal from the Coordinator  20 , it may emit a distinct alerting tone. As an example, if briefcase  15  is being carried away by someone other than its owner, the distinct alert tone might deter the person from walking away with briefcase  15 . In the situation where the user  11  would like to locate an object with an ID Tag  30  that is not clearly visible, the user  11  may select the particular ID Tag  30  and send it a “beep” message. If that ID Tag  30  is within range of the radio broadcast, it will respond by beeping the enunciator  33 . 
   Additionally in a particular embodiment, the ID Tag  30  contains a visible light emitting diode (LED)  32 , or beacon  32 , which may be used to illuminate the ID Tag  30 , making it easier to visually locate. Functioning in much the same way as sound generator  33 , LED  32  provides a silent means of visually locating an ID Tag  30  in such situations where an audible sound is not desired. Such a situation could include when the ID Tag  30  is affixed to luggage that is passing through a security checkpoint at an airport. 
   Referring to  FIG. 5 , a block diagram of main electronic components is illustrated for an embodiment of ID Tag  30 . At the heart of ID Tag  30  is a single microelectronics chip  51 . Chip  51  is a highly-integrated very low-power circuit that combines a low-power radio-frequency transceiver, microprocessor, Flash memory used to store the program, and RAM used to store temporary information. System  10  takes advantage of latest advancements in microcircuit technology wherein smaller, lower power, low-cost integrated circuits are known and available allowing for system  10  that is commercially viable. A radio antenna  50  connects to the integrated Transceiver chip  51 . In this embodiment, an “F” type antenna is manufactured onto the printed circuit board. In another embodiment, the antenna may be a chip-type antenna. In this embodiment, a visual light-emitting diode  32 , an enunciator  33  and a pushbutton switch  31  provide for user input/output. A motion detector chip  53  detects when the ID Tag  30  is moving. 
   C. The Coordinator 
     FIG. 2A  through  FIG. 20  illustrate one embodiment of the Coordinator  20 , having an outer enclosure which is relatively small in size and lightweight that may be carried by the user  11  in a hand, a shirt or jacket pocket, or clipped to a purse strap or belt via a clip  27 . An eye-hook  28  molded into the case permits the attachment of a strap  26  so that the Coordinator  20  may be held more securely in the hand or worn around a user&#39;s  11  neck. The housing is preferably made of a tough and durable material. In a particular embodiment material housing is made of molded plastic, and is water resistant. The device  20  is battery powered and further battery  42  may either be replaceable or rechargeable through the external power plug  24 . In one embodiment, a rechargeable battery  42  may be recharged from voltage derived from the USB port  25  when said port  25  is connected to a personal computer  90  ( FIG. 9 ). 
   In an embodiment of the present invention, the Coordinator  20  has user input controls  22  and  23  and a display screen  16 , using either a reflective or backlight type liquid crystal display (LCD)  16 , an audible sound enunciator  18  and a visible light emitting diode (LED)  25 . The user  11  employs user controls  22  and  23  to navigate through the menus programmed into the Coordinator  20 , and the display screen  16  is used to display the various menu options to the user  11 . 
   User control  22 , in this embodiment, is a single multi-function thumbwheel selector. This multi-function thumbwheel switch  22  makes it easy for the user  11  to operate the Coordinator  20  holding in one hand and operating the user controls  13  and  14  with a single thumb or finger. The multi-function thumbwheel switch  22  is rotated downward to advance to the next menu item  16   d , rotated upwards to return to the previous menu item  16   d , and pushed inwards to select the current menu item  16   d . Pushbutton switch  23  is used to cancel or exit from a menu mode or function and return to the previous menu level. 
   Further in a particular embodiment, Coordinator  20  has an LCD display  16  which is used to display to the user  11  many kinds of information pertinent to the operation and usage of the system  10 . This LCD display  16  may be custom built such that alphanumeric characters and graphic characters are presented to user  11 . The current mode of operation and menu items are displayed in areas  16   c  and  16   d  using alphanumeric characters. In this embodiment, the LCD display presents Roman characters for English, Spanish, and most European languages. In another embodiment display  16  may present characters used in Asian languages such as Chinese, Japanese and Korean, or Russian (Cyrillic), Hebrew, Arabic and other languages. Components of Coordinator  20  could further be integrated into a cellular device. 
   Additionally, in this embodiment, Coordinator  20  conveys the distance and motion that an ID Tag  30  may have relative to the user  11  holding Coordinator  20 . Many prior art devices have presented components and methods for calculating a specific position or exact distance and direction of an object relative to user  11 . However, these techniques require the utilization of extra antennas, electronic circuitry, processing logic and displays, or even external systems such as GPS, which add cost and complexity to such devices. The present invention concerns itself primarily with addressing the user&#39;s question “where is my . . . ?” or, “is my . . . in my immediate proximity?” The moving average of the ID Tag  30  received signal strength is displayed in the bar indicator  16   a  and the relative direction of motion of the ID Tag  30  is displayed in the Motion indicator  16   b.    
   Table 1 illustrates icons  16   b  represented in LCD display  16  to convey the most recent motion direction and relative distance information to user  11 . In addition to the display of motion indicators  16   b , Table 1 presents a legend of beep sounds that provide an audible indication as to the nature of change in relative motion of Coordinator  20  to ID Tag  30 . For example, a single beep may indicate that one of the objects being tracked is moving closer (or that the user  11  is moving closer to the object). In a case where the user  11  is moving toward multiple objects being tracked  13 - 15 , as each object  13 - 15  is polled, a beep sound will be generated for each object. A rapid double-beep could indicate the user  11 , or objects  13 - 15  are moving apart. Three rapid consecutive beeps may indicate to the user  11  an object not recently in proximity that has arrived into proximity. A prolonged beep may indicate to the user  11  that an object is now longer in proximity. As each alert beep signal is generated, the common name  16   d  of that object creating the alert signal is displayed on the LCD display  16  in  16   d  together with the Motion Indicator  16   b  from Table 1. 
   
     
       
         
             
           
             
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   The Coordinator  20  can be powered by a small watch-type battery  42 , for example. Owing to the extremely low power consumption of the integrated radio transceiver and microprocessor technology  41 , battery life of several months to more than a year can be expected even under continuous use. The battery voltage of the Coordinator  20  is constantly monitored by circuitry built into the electronic chip  41 . As the Coordinator  20  battery voltage drops below a proper operating value, user  11  is alerted that the battery  42  should be replaced or recharged. The battery  42  is accessible from the battery compartment cover  29 . In one embodiment, a rechargeable watch-type battery may be installed and recharged by plugging in a battery-charger into DC input  24 . 
   The Coordinator  20  may be connected to a personal computer through a small USB connector  25  located on the side of the Coordinator  20  ( FIG. 2B ). An application program written specifically for programming the Coordinator  20  using a Personal Computer  90  connected through the USB port  25  on Coordinator  20  permits the user  11  to enter common names  16   d  for each Transponder ID Tag  30   a - 30   c.    
   D. Communication Between Coordinator and Transponder ID Tags 
   Each ID Tag  30  is manufactured with a unique digital address or Media Access Control (MAC) address embedded into the electronic circuit or chip  41  and  51 . The MAC address consists of 6 sets of 2-digit hexadecimal numbers, as defined by the IEEE MAC-48 standard. Each hexadecimal number may range in value from 00 to FF (hexadecimal numbers are 0 thru 9, A, B, C, D, E, and F allowing for 16 decimal equivalent values per digit). The total possible unique MAC addresses thus is 2 48  or 281, 474, 976, 710, 656 possible MAC addresses. 
     FIG. 6  and  FIG. 7  are flowchart diagrams depicting the overall program logic for the Coordinator  20  and ID Tag  30  respectively.  FIG. 8  is a flowchart depicting the process of how an ID Tag  30  becomes associated with a particular Coordinator  20 . 
   E. Associating an ID Tag with a Coordinator 
   The first time an ID Tag  30  is to be used with a particular Coordinator  20 , the unique ID Tag  30  MAC address for that particular ID Tag  30  must become associated with the Coordinator  20 . That is, the MAC address of the ID Tag  30  must be recorded inside the memory  41  or “device list” in the Coordinator  20 , adding it to the list of ID Tags  30  to be monitored. The procedure to associate an ID Tag  30  with a Coordinator  20  involves placing both the Coordinator  20  into the association procedure  69 , and placing the ID Tag  30  to be associated into association procedure  78 . Placing Coordinator  20  into association mode is accomplished when the user  11  navigates through the menus using controls  22  and  23  until they find the “Associate ID Tag” function displayed in the LCD display  16 , in the text line  16   d . Depressing user control  22  selects this function and initiates the “Associate” procedure  69 . Placing the ID Tag  30  into association mode  78  is accomplished when user  11  presses and holds button  31  for a specific period of time, typically 5 seconds. When the ID Tag  30  enters association procedure  78 , it transmits a start of association response together with the MAC address  87 . Next, an “Associating” response  80  it transmitted back to ID Tag  30  via transceiver  51  and ID Tag  30  receives “Associating” response. The Coordinator  20  then determines if the MAC address received is in a list  81 . If so, “Previoiusly associated”  82  is transmitted. If not, MAC address is added to list  83 . Subsequently, user enteres the common name  84  such as “briefcase,” “car keys,” or “camera.” Coordinator  20  then transmits “Associated”  85  and for particular Tag  30  assocation procedure is done  86 . 
   This association procedure  78  is required only once when a new ID Tag  30  is brought into use with a particular Coordinator  20 . A user  11  may possess more than one Coordinator  20 , and each ID Tag  30  must be individually associated with each Coordinator  20 . A PC-based application program allows the user  11  to create and edit common names, and upload the names to the Coordinator  20  through the USB port  25 . The application program may also be used to copy ID Tag  30  common names between other Coordinators  20 . 
   F. Determining Proximity of ID Tags 
   ID Tags  30  that are associated with a Coordinator  20  comprise the list of active ID Tags  30 . The particular ID Tag  30  may now be affixed to an object and used for keeping track of that object. With each the various objects a user  11  may want to track affixed with a unique ID Tag  30 , the Coordinator  20  commences maintaining communication with each ID Tag  30 . Referring to  FIG. 6  and  FIG. 7 , a “Hello” command  61  is transmitted containing the first and then subsequently the next MAC address in the current list of objects to track. Each and every ID Tag  30  wakes up from a power-saving sleep mode  79  long enough to for the transceiver  51  to receive a broadcast. If the MAC address of the ‘Hello’ command  61  matches the MAC address  70  of that particular ID Tag  30 , then that ID Tag  30  transmits a Reply Status  75  that is processed during a timing interval  74 . In the case where the call button  31  was depressed by user  11 , “Announce” response  63  is made via sound generator  18 . Physical events occurring with any ID Tag  30  may include but are not limited to: detecting motion  53  using a commercially available x/y/z motion detection chip  53 ; detecting changes in visible light  72  using a commercially available light detection chip; or the pressing of the call button  31 . These events are saved  74  as response data to be sent back to a calling Coordinator  20  the next time the ID Tag  30  responds  70  to the “Hello” request  61 . 
   The strength of Coordinator  20  transmission signal received  73  by the ID Tag  30  is measured by a process built into the transceiver chip  51  and saved as a reply response  74  along with the current battery voltage level  52  which is also measured by a process built into the transceiver chip  51 . In a preferred embodiment, transceiver chip  51  compares a transmit power of the ID Tag  30  to the last signal strength received  73 , and then transceiver chip  51  can optimize the transmit power of ID Tag  30  in the next communication cycle. 
   The received signal strength  73  of a transmitted broadcast  61  is dependent upon numerous physical and environmental factors and influences. Lending to the nature of radio signal propagation, the present invention does not attempt to measure or correlate signal strength with the actual distance, as may be measured in feet or meters, between objects. Rather, the present invention uses the changes in signal strength sampled over time between each object polled to determine if the object or the user  11  is moving relative to the last sample  73 . Changes in relative signal strength are processed  65  taking into account if motion was detected  53  in ID Tag  30 , or if motion  43  was detected in Coordinator  20 , or both. From this data, it may be determined that either the object may be moving away from the user  11 ; the viewer may be moving away from the object; or that no change between the relative proximity of viewer to object has occurred. Further the flow logic will process  67  key entries  22  and  23  and whether the “Associate” function  68  has been selected. 
   G. Coordinator Interface with PC and Application Program 
     FIG. 9  depicts how a Coordinator  20  may be connected to a Personal Computer (PC)  90  using a standard USB cable  91 . USB cable  91  connected to the Coordinator  20  to the USB port  25 . An application program installed on PC  90  then provides the user  11  with many functions, enabling user  11  to more effectively manage the information contained in the Coordinator  20 , or multiple Coordinators  20 . 
   Common names are associated with MAC addressed of ID Tags  30  so that it is easier for the user  11  to identify which object or ID Tag  30  is being interacted. Because of simple user controls  22  and  23 , entering alphanumeric characters is best done from the PC  90 . The application program is programmed to communicate with the Coordinator  20  such that it facilitates the uploading for the MAC address tables contained in the memory of the Coordinator  20 . Using a menu function in the application program, the user  11  enters the common name for each MAC address. The MAC address is printed on the back of each ID Tag  30  at the time of manufacturing for easy visual identification. The completed list is saved on the hard disk of the PC  90  according to the present invention, and then uploaded back into the Coordinator  20 . 
   Through the connection  91  of the Coordinator  20  to PC  90 , additional functions may be performed that are either may not be available from the Coordinator  20  directly, or are made easier to enter using the PC application. These include, but are not limited to: updating the firmware program contained in the microprocessor  41  memory; enable or disable the audible beep of the Coordinator  20 ; allowing configuration data from one Coordinator  20  to be transferred to another Coordinator  20 ; and display a list of options that describe the individual behaviors of each ID Tag  30 . 
   The individual behaviors of each ID Tag  30  many include:
         emit a short audible beep, or not, upon entering the immediate proximity of a Coordinator  20 ;   emit a short auditable beep, or not, upon leaving the immediate proximity of a Coordinator  20 ;   emit a “warning” beep tone upon leaving the immediate proximity of a Coordinator  20 ;   emit an audible beep tone, or not, upon receiving a “call” from a Coordinator  20 ; and   illuminate the visible LED  32 , or not, upon receiving a “call” from a Coordinator  20 .       

   Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the invention. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purposes of example and that it should not be taken as limiting the invention as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the invention includes other combinations of fewer, more or different elements, which are disclosed in above even when not initially claimed in such combinations. 
   While the particular System and Method for Locating Objects as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims. 
   Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalently within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements.