System for monitoring and locating people and objects

A method, computer program product and system for monitoring and locating an object using secure communications without relying on GPS. A monitoring device may activate a monitored unit (unit monitored by monitoring device) by transmitting a seed of an algorithm and a time synchronization to the monitored unit. The seed and time synchronization may be used in conjunction with an algorithm, e.g., frequency hopping table, stored in both the monitoring device and the monitored unit, to allow both the monitoring device and the monitored unit to communicate with one another at a uniquely synchronized time and frequency thereby making it more difficult for a third party to locate the monitored unit. An alert may be generated when the monitored unit is located beyond a predetermined zone. The monitored unit may be located by activating a directional antenna in conjunction with a digital compass on the monitoring device.

TECHNICAL FIELD

The present invention relates to the field of locating systems, and more particularly to a monitoring and locating system implementing secure communications between the monitoring device and the monitored unit to lessen the ability of a third party locating the object, e.g., person, automobile, attached to the monitored unit.

BACKGROUND INFORMATION

There are numerous methods and systems for locating moveable objects such as automobiles, pets and people. One such system for locating moveable objects, such as a person, utilizes a Global Positioning Sensor (GPS) locator device that may be attached to the object, e.g., carried by the person. The GPS locator device may receive and triangulate signals from each of three or more geostationary satellites and determine the geographical coordinates of the device's current location. The geographical coordinates may be made available to an individual via a web site by the GPS locator device transmitting the GPS coordinates to either a device monitoring the GPS locator device or to a centralized location. However, GPS locator devices may not be able to receive and triangulate signals because the signals may be blocked or scattered by a variety of objects such as dense tree canopies, heavy clouds, metal roofs, layers of rock, concrete or canyon walls. For example, GPS locator devices may not be able to receive and triangulate signals in or around buildings or homes or in the woods with lots of vegetation. Hence, GPS may be of no assistance in locating an object in certain environments as discussed above. Further, in order for the GPS locator device to include both the capabilities of determining the geographical coordinates of the device's current location and transmitting that information to another device or centralized location, the GPS locator device becomes bulky and costly to implement.

One system that does not utilize GPS to locate objects, such as children, uses a monitoring device configured to monitor the position of a child by detecting the signal strength of a radio frequency carrier from a transmitter attached to the child. If the signal of the radio frequency carrier is too weak, the child is too far away from the adult who has the monitoring device. When this happens, the adult is informed that the child has wandered too far away through the use of an audio tone or through the use of vibrations coming from the device. Once the adult is notified that the child is too far away, the device also has a locating display for indicating the relative direction of the child with respect to the adult. However, since the transmitter worn by the child simply transmits a signal with no unique identification code at a particular frequency, a third party, e.g., potential abductor, may be able to intercept the signal and with a similar monitoring device track the child. Furthermore, since the transmitter worn by the child simply transmits a signal with no unique identification code at a particular frequency, a third party, e.g., potential abductor, may be able to transmit false information to the monitoring device.

Therefore, there is a need in the art for a monitoring and locating system that does not rely upon GPS and provides secure communication making it more difficult for a third party, e.g., potential abductor, potential thief, to be able to locate the object, e.g., child, automobile, as well as transmit false information to the monitoring device and/or monitored unit.

SUMMARY

The problems outlined above may at least in part be solved in some embodiments of the present invention by the monitoring device transmitting a seed of an algorithm and a time synchronization to the monitored unit which will be used in conjunction with an algorithm, e.g., frequency hopping table, stored in both the monitoring device and the monitored unit, to communicate at a particular time and frequency between one another. Time synchronization may refer to the time the monitoring device transmits the seed. Each subsequent transmission from the monitored unit to the monitoring device is in a specific time slot, synchronized with the monitoring device and at a frequency that changes pseudo-randomly. A response from the monitoring device resynchronizes the time slot. A seed may refer to a multiple bit number, e.g., 16-bit number, used in conjunction with these time slots to select a particular frequency stored in the algorithm, e.g., frequency hopping table. Hence, the frequency of each communication between the monitoring device and the monitored unit changes according to the algorithm stored in both the monitoring device and the monitored unit thereby making it more difficult for a third party, e.g., potential abductor, potential thief, to be able to locate the object, e.g., child, automobile, as well as transmit false information to the monitoring device and/or monitored unit.

In one embodiment of the present invention, a method for monitoring and locating an object, e.g., person, automobile, may comprise the step of activating a unit to be monitored by a monitoring unit. The method may further comprise receiving a first packet of data form the monitored unit where the first packet of data comprises an identification. The method may further comprise transmitting a seed of an algorithm to the monitored unit if the identification associated with the first packet of data is a valid identification. The method may further comprise measuring a signal strength of a second packet of data if the second packet of data was received at an expected frequency from the monitored unit. The measured signal strength of the second packet of data indicates an approximate distance the monitored unit is located from the monitoring device.

In another embodiment of the present invention, a system may comprise a monitored unit attached to an object. The monitored unit may comprise a memory unit operable for storing a computer program product operable for determining if the monitored unit has been tampered with. The monitored unit may further comprise a processor coupled to the memory unit. The monitored unit may further comprise an emitter coupled to the processor where the emitter is configured to emit infrared signals to the skin of an individual. The monitored unit may further comprise a detector coupled to the processor where the detector is configured to receive reflections of the emitted infrared signals from the skin. The processor, responsive to the computer program, may comprise circuitry operable for determining if an intensity of the reflections of the emitted infrared signals is less than a threshold. The processor may further comprise circuitry operable for transmitting an indication that the monitored unit has been tampered with if the intensity of the reflections of the emitted infrared signals is less than the threshold.

The foregoing has outlined rather broadly the features and technical advantages of one or more embodiments of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.

DETAILED DESCRIPTION

FIG.1—System for Monitoring and Locating an Object

FIG. 1illustrates one embodiment of a system100not relying upon GPS for locating an object, e.g., person, automobile, baby carriage. Referring toFIG. 1, system100may comprise a monitoring device101configured to monitor one or more units102, e.g., wristband type of device worn by a child, attached to one or more objects. In one embodiment, monitoring device101may be configured to monitor unit102at a distance between 300 to 1,000 feet. It is noted that monitoring device101may be configured to monitor unit102attached to any type of object.

Returning toFIG. 1, monitoring device101may comprise a processor103coupled to an activation/deactivation unit104, a digital compass105, a display106, e.g., liquid crystal display, a memory107, a battery108, button(s) and/or switch(es)109, Light Emitting Diode(s) (LEDs)110, a beeper111, a vibrator112, and a transmitter/receiver circuit113. Transmitter/receiver circuit113may be coupled to an antenna switch114which may be coupled to a directional antenna115and an omni directional antenna116. It is noted that monitoring device101may comprise other and/or additional circuitry providing the same functionality as discussed herein and thatFIG. 1is illustrative.

Referring toFIG. 1, memory107, e.g., non-volatile memory, may be configured to store a program to perform the steps of the method for activating unit102as described further below in conjunction withFIG. 2. Further, the program stored in memory107may include an algorithm used to implement frequency hopping as described further below. Further, the program stored in memory107may perform the steps of the method for monitoring monitored unit102as described further below in conjunction withFIG. 3. Further, the program stored in memory107may perform the steps of the method for locating the monitored unit in the locate mode of operation as described further below in conjunction withFIG. 6. Further, the program stored in memory107may perform the steps of informing the user of unit102to return to “base” as described further below in conjunction withFIG. 9. Further, the program stored in memory107may perform the steps of deactivating unit102as described further below in conjunction withFIG. 10. Processor103may be configured to execute the instructions of the program listed above. It is noted that the steps of the methods performed by the program mentioned above may in an alternative embodiment be implemented in hardware such as in an Application Specific Integrated Circuit (ASIC).

Returning toFIG. 1, as stated above, processor103may be coupled to a activation/deactivation unit104. Activation/deactivation unit104may be configured to transmit a signal indicating to unit102to enter either an activation mode or a deactivation/sleep mode. Activation mode may refer to a mode in which unit102is able to both receive and transmit data to monitoring device101. Deactivation/sleep mode may refer to a power saving mode of operation in which unit102is only able to receive data from monitoring device101. In one embodiment, activation/deactivation unit104may be configured to transmit the signal over a very short range, e.g., inches, thereby preventing other units102in close proximity to monitoring device101from accidentally being activated. A discussion of activating or deactivating unit102is provided further below.

Digital compass105may be used in the “locate mode” of operation, as discussed in further detail below in conjunction withFIGS. 3–6, which may be configured to determine the direction of a received signal transmitted from unit102. An example of a digital compass105is the HMC 1052 manufactured by Honeywell™ International (Honeywell™ International is located at 101 Columbia Road, P.O. Box 4000, Morristown, N.J. 07962). The directional information of a received signal may be displayed to a user of monitoring device101via display106.

Battery108may supply the necessary operating power for the circuitry and components of monitoring device101. Battery108may be a standard carbon or lithium battery, or a rechargeable type battery such as nickel metal hydride (NiMH), nickel cadmium (NiCAD) or lithium-ion.

Monitoring device101may comprise input/output devices such as button(s)/switch(es)109, LEDs110, beeper111, vibrator112, and/or display106. Data may be inputted to monitoring device101through button(s)/switch(es)109, e.g., inputting a maximum distance the monitored unit102should be located from monitoring device101as discussed below in conjunction withFIG. 2, inputting a command to enter “locate mode” as discussed further below in conjunction withFIG. 3, inputting a command to exit “locate mode” as discussed further below in conjunction withFIG. 6, inputting a command to inform unit102to “return to base” as discussed further below in conjunction withFIG. 9, inputting a command to deactivate unit102as discussed further below in conjunction withFIG. 10. Output may be received by the user of monitoring device101through LEDs110, beeper111, vibrator112and/or display106, e.g., outputting an indication that monitored unit102is located beyond a pre-selected maximum distance, e.g., 1,400 feet, as discussed further below in conjunction withFIG. 3, outputting an indication that monitoring device101has not received a signal at an anticipated time and at an expected frequency from unit102for a pre-determined period of time as discussed further below in conjunction withFIG. 3, outputting an option to enter the “locate mode” as discussed further below in conjunction withFIG. 3, outputting a polar plot indicating signal strength and direction of the received signal as discussed further below in conjunction withFIG. 6. It is noted that monitoring device101may comprise other types of input/output devices, e.g., alphanumeric characters, not illustrated and that such input/output devices would be known to a person of ordinary skill in the art. It is further noted that embodiments incorporating such input/output devices would fall within the scope of the present invention.

Transmitter/receiver circuit113may be configured to transmit information to and receive information from monitored unit102. Upon activating unit102as discussed above, a “seed”, a unique identification assigned to unit102, as well as an identification used to identify monitoring device101, may be transmitted to monitored unit102. Further, upon activating unit102, a “time synchronization” may be transmitted to unit102. “Time synchronization” may refer to the time that monitoring device101transmitted the above information. Each subsequent transmission from monitored unit102to monitoring device101is a specific time slot synchronized with monitoring device101. A response from monitoring device101resynchronizes the time slot. A “seed” may refer to a multiple bit number, e.g., 16-bit number, used in conjunction with these time slots to select a particular frequency stored in an algorithm, e.g., frequency hopping table. The algorithm may be stored in both monitoring device101and monitored unit102. As discussed below, the algorithm may be stored in a memory unit in monitored unit102prior to a customer purchasing monitored unit102. In one embodiment, the frequencies selected may correspond to frequencies between 902–928 MHz in the license-free ISM band. In one embodiment, system100may be configured to implement frequency hopping spread spectrum in the license-free ISM band by selecting50hopping frequencies in the algorithm using the seed and time slots as discussed above. It is noted that frequency hopping spread spectrum is known in the art and therefore will not be described in detail for sake of brevity.

In one embodiment, monitoring device101may be configured to coordinate multiple monitored units102that use the same algorithms, e.g., frequency hop tables, without accidentally activating a different monitored unit102than the one intended by ensuring these units102are time shifted from each other. The coordination may be accomplished via software stored in memory107.

Antenna switch114may be configured to activate directional antenna115to receive transmitted information when monitoring device101operates in “locate mode.” Locate mode may refer to the mode of operation in which monitored unit102increases its rate of transmissions to aid in monitoring device101tracking and determining the approximate location of monitored unit102. For example, the locate mode of operation may be enacted when monitored unit102is located beyond a pre-determined maximum distance from monitoring device101or when monitored unit102has been tampered with as discussed in conjunction withFIGS. 3–6and8. In one embodiment, directional antenna115may be implemented as a two-element array. Each element may be an omni-directional loop antenna that may be placed about a quarter wavelength apart. Transmitter/receiver circuit113may include beam-forming circuitry that combines the signals received from the two-element array to create a cardiod beam pattern. A cardiod beam pattern typically has a high gain lobe in one direction and a deep null in the opposite direction. When tracking monitored unit102, the null may be utilized to more accurately locate unit102. Directional antennas are well known to persons of ordinary skill in the art and will therefore not be discussed in further detail for the sake of brevity.

Antenna switch110may also be configured to activate an omni directional antenna116when monitoring device101operates in “monitoring mode.” Monitoring mode may refer to the mode of operation in which monitoring device101monitors the approximate distance unit102is located from monitoring device101. Omni-directional antennas are well known to persons of ordinary skill in the art and will therefore not be discussed in further detail for the sake of brevity.

It is noted that other features of monitoring device101will be discussed further below in conjunction withFIGS. 2–10.

Returning toFIG. 1, monitored unit102may comprise a processor117coupled to an activation/deactivation sensor118, a memory119, a battery120, LEDs121, a beeper122, button(s) and/or switch(es)123, a tamper sensor124, and a transmitter/receiver circuit125. Transmitter/receiver circuit125may be coupled to an omni directional antenna126. It is noted that monitored unit102may comprise different circuitry providing the same functionality as discussed herein and thatFIG. 1is illustrative.

Activation/deactivation sensor118may be configured to receive a signal to activate or deactivate monitored unit102from activation/deactivation unit104. In one embodiment, activation/deactivation sensor118may include an infrared detector and emitter configured to detect and transmit signals in the infrared band from and to monitoring device101, respectively.

Processor117may be configured similarly as processor103. In one embodiment, memory119, e.g., non-volatile memory, may store a program for transmitting packets of data at an increased rate during the “locate mode” of operation as described further below in conjunction withFIGS. 4–5. Further, the program stored in memory119may perform the steps of enacting the locate mode of operation as described further below in conjunction withFIGS. 4–5. Further, the program stored in memory119may include the functionality of notifying monitoring device101when monitored unit102has been tampered with as described further below in conjunction withFIG. 8. Further, the program stored in memory119may include the functionality of notifying the user of monitored unit102to return to “base” as described further below in conjunction withFIG. 9. Further, the program stored in memory119may include the functionality of deactivating monitored unit102as described further below in conjunction withFIG. 10. Processor117may be configured to execute the instructions of the programs listed above. It is noted that the steps of the methods performed by the program mentioned above may in an alternative embodiment be implemented in hardware such as in an Application Specific Integrated Circuit (ASIC).

Battery120may supply the necessary operating power for the circuitry and components of monitored unit102. Battery120may be a standard carbon or lithium battery, or a rechargeable type battery such as nickel metal hydride (NiMH), nickel cadmium (NiCAD) or lithium-ion.

Monitored unit102may comprise input/output devices such as LEDs121, beeper122and button(s)/switch(es)123. Data may be inputted to monitored unit102through button(s)/switch(es)123. Output may be received by the user of monitored unit102through LEDs121and beeper122, e.g., outputting an indication that monitored unit102has been tampered with as discussed further below in conjunction withFIG. 8, outputting an indication to return to base as discussed further below in conjunction withFIG. 9. It is noted that monitored unit102may comprise other types of input devices as well as output devices, e.g., display, alphanumeric characters, not illustrated and that such input/output devices would be known to a person of ordinary skill in the art. It is further noted that embodiments incorporating such input/output devices would fall within the scope of the present invention.

Tamper sensor124may be configured to detect monitored unit102being tampered with such as removing monitored unit102from an object, e.g., wrist of a child. A more detail description of detecting the tampering of monitored unit102is described further below in conjunction withFIGS. 7–8.

Transmitter/receiver circuit125may be configured similarly as transmitter/receiver circuit113. Transmitter/receiver circuit125may be configured to transmit information to and receive information from monitoring device101via omni directional antenna126. Omni directional antenna126is configured similarly as omni directional antenna116.

As stated in the Background Information section, there is a need in the art for a monitoring and locating system that makes it more difficult for a third party, e.g., potential abductor, potential thief, to be able to locate the object, e.g., child, automobile, as well as transmit false information to the monitoring device and/or monitored unit.FIGS. 2–10describe such a system by implementing frequency hopping thereby making it more difficult for a third party, e.g., potential abductor, potential thief, to be able to locate the object as well transmit false information to the monitoring device and/or monitored unit. A method for activating and setting up monitored unit102is described below in conjunction withFIG. 2. A method for monitoring monitored unit102is described further below in conjunction withFIG. 3. A method for enacting the “locate mode of operation” on monitored unit102from monitored unit's102perspective is described further below in conjunction withFIG. 4. An alternative method for enacting the “locate mode of operation” on monitored unit102from monitored unit's102perspective is described further below in conjunction withFIG. 5. A method for locating monitored unit102in the locate mode of operation is described further below in conjunction withFIG. 6.FIG. 7illustrates tamper sensor124of monitored unit102configured to detect the removal of monitored unit102from its attached object.FIG. 8is a method for monitored unit102for detecting and informing monitoring device101if monitored unit102was tampered with.FIG. 9is a method for requesting the user of monitored unit102to return to base.FIG. 10is a method for deactivating monitored unit102.

FIG.2—Method for Activating and Setting Up Monitored Unit

FIG. 2is a flowchart of one embodiment of the present invention of a method200for activating and setting up monitored unit102.

Referring toFIG. 2, in conjunction withFIG. 1, in step201, monitoring device101transmits a signal in close proximity, e.g., inches, to monitored unit102to awaken monitored unit102from deactivation/sleep state. That is, in step201, monitoring device101transmits a signal in close proximity, e.g., inches, to monitored unit102to activate monitored unit102. Once monitored unit102is activated, monitored unit102responds and initiates communication with monitoring device101by radio frequency communications. In one embodiment, activation/deactivation unit104may transmit a signal to activate monitored unit102to be received by activation/deactivation sensor118of monitored unit102. As stated above, activation/deactivation sensor118may include an infrared detector and emitter configured to detect and transmit signals in the infrared band from and to monitoring device101. In one embodiment, activation/deactivation unit104may transmit a special pulse sequence that includes the identification of monitoring device101via an infrared link to activation/deactivation sensor118. By monitoring device101transmitting the special pulse sequence in close proximity to monitored unit102, the likelihood of accidentally activating a nearby monitored unit102is lessened.

In step202, monitoring device101receives a packet of data from the activated monitored unit102that includes the identification of the monitoring device101that activated monitored unit102as well as the identification of monitored unit102.

In step203, monitoring device101determines if the identification of a monitoring device101is valid. That is, monitoring device101determines if the identification of a monitoring device101matches its own identification.

If the identification is not valid, then, in step204, monitoring device101ignores the received packet of data. The packet of data may have been intended for another monitoring device101that activated this particular monitored unit102.

If, however, the identification is valid, then, in step205, monitoring device101transmits a seed and a time synchronization, as discussed above, to monitored unit102. Further, if the identification is valid, monitoring device101may transmit an identification assigned to monitored unit102. Monitoring device101may be said to be in “monitoring mode” at this point in time as will be described below in conjunction withFIG. 3.

It is noted that method200may include other and/or additional steps that, for clarity, are not depicted. It is noted that method200may be executed in a different order presented and that the order presented in the discussion ofFIG. 2is illustrative. It is further noted that certain steps in method200may be executed in a substantially simultaneous manner.

FIG.3—Method for Monitoring Monitored Unit

FIG. 3is a flowchart of one embodiment of the present invention of a method300for monitoring monitored unit102.

Referring toFIG. 3, in conjunction withFIG. 1, in step301, monitoring device101makes a determination if it received a packet of data from monitored unit102at the appropriate time and at the expected frequency. The anticipated time and expected frequency may be determined from an algorithm stored in memory107as described above.

If monitoring device101did not receive received a packet of data from monitored unit102at the appropriate time and at the expected frequency, then, in step302, monitoring device101makes a determination if the time that monitoring device101has not heard from monitored unit102exceeds a threshold, e.g., three seconds. If the time that monitoring device101has not heard from monitored unit102does not exceed a threshold, then monitoring device101makes a determination if it received a packet of data from monitored unit102at an expected time and frequency in step301.

If, however, the time that monitoring device101has not heard from monitored unit102exceeds a threshold, then, in step303, monitoring device101outputs an indication, e.g., lights from LEDs110, a beep from beeper111, vibration from vibrator112, to the user of monitoring device101that monitoring device101has not heard from monitored unit102for over a threshold of time.

Returning to step301ofFIG. 3, if monitoring device101did receive a packet of data from monitored unit102at the appropriate time and at the expected frequency, then, in step304, monitoring device101makes a determination if the packet of data contains the valid identification of monitoring device101. Each time monitored unit102communicates with monitoring device101, monitored unit102may transmit a packet of data that includes the identification of a monitoring device101.

If the identification is not valid, then, in step305, monitoring device101ignores the received packet of data. The packet of data may have been intended for another monitoring device101.

If, however, the identification is valid, then, in step306, monitoring device101measures the signal strength of the received packet of data. In step307, monitoring device101determines if the signal strength is below a threshold.

If the signal strength at or above the threshold, then, in step308, monitoring device101transmits an acknowledgment to monitored unit102at a frequency determined by the algorithm, e.g., frequency hopping table, stored in memory107.

If, however, the signal strength is below the threshold, then, in step309, monitoring device101outputs an indication, e.g., lights from LEDs110, a beep from beeper111, vibration from vibrator112, to the user of monitoring device101that monitored unit102is located beyond a “comfort zone.” The “comfort zone” may refer to a distance determined by the user of monitoring device101as to how far monitored unit102should be located from monitoring device101.

In step309, monitoring device101transmits an acknowledgment to monitored unit102at a frequency determined by the algorithm, e.g., frequency hopping table, stored in memory107.

Referring to steps303and310, upon outputting an indication to the user of monitoring device101that monitoring device101has not heard from monitored unit102for over a threshold of time and transmitting an acknowledgment, respectively, monitoring device101, in step311, provides the user of monitoring device101an option of entering the “locate mode” of operation.

In step312, monitoring device101makes a determination if it received a request to enter the locate mode of operation. If monitoring device101does not receive a request to enter the locate mode of operation, then monitoring device101makes a determination if it received a packet of data from monitored unit102at the appropriate time and frequency in step301.

If, however, monitoring device101does receive a request to enter the locate mode of operation, then, in step313, monitoring device101enters the locate mode of operation. A description of different methods of enacting the locate mode of operation on monitored unit102is provided below in conjunction withFIGS. 4–5. A description of monitoring device101locating monitored unit102during the locate mode of operation is provided below in conjunction withFIG. 6.

It is noted that method300may include other and/or additional steps that, for clarity, are not depicted. It is noted that method300may be executed in a different order presented and that the order presented in the discussion ofFIG. 3is illustrative. It is further noted that certain steps in method300may be executed in a substantially simultaneous manner.

FIG.4—Method for Enacting the Locate Mode of Operation on Monitored Unit

FIG. 4is a flowchart of one embodiment of the present invention of a method400for enacting the locate mode of operation on monitored unit102from monitored unit's102perspective.

Referring toFIG. 4, in conjunction withFIG. 1, in step401, monitored unit102receives a signal to enter the locate mode of operation from monitoring device101. In step402, monitored unit102transmits packets of data at an increased rate at expected frequencies according to an algorithm, e.g., frequency hopping table, stored in memory119. For example, monitored unit102may transmit packets of data at expected frequencies every 1 second during the monitoring mode of operation. During the locate mode of operation, monitored unit102may transmit packets of data at expected frequencies every 200 milliseconds.

In step403, monitored unit102determines if it received a signal from monitoring device101to exit the locate mode of operation. If not, then monitored unit102continues to transmit packets of data at an increased rate at expected frequencies in step402.

If, however, monitored unit102receives a signal from monitoring device101to exit the locate mode of operation, then monitored unit102exits the locate mode of operation in step404. In step405, monitored unit102transmits packets of data at a normal rate, e.g., 1 transmission per second, at expected frequencies according to an algorithm, e.g., frequency hopping table, stored in memory119. That is, monitored unit102enters the monitoring mode of operation and transmits packets of data at the normal rate of transmission.

It is noted that method400may include other and/or additional steps that, for clarity, are not depicted. It is noted that method400may be executed in a different order presented and that the order presented in the discussion ofFIG. 4is illustrative. It is further noted that certain steps in method400may be executed in a substantially simultaneous manner.

FIG.5—Alternative Method for Enacting the Locate Mode of Operation on Monitored Unit

FIG. 5is a flowchart of an alternative embodiment of the present invention of a method500for enacting the locate mode of operation on monitored unit102from monitored unit's102perspective.

Referring toFIG. 5, in conjunction withFIG. 1, in step501, monitored unit102determines if it received an acknowledgment at the appropriate time from monitoring device101at the expected frequency according to the algorithm, e.g. frequency hopping table, stored in memory119.

If monitored unit102received an acknowledgment at the appropriate time from monitoring device101at the expected frequency, then, in step502, monitored unit102transmits packets of data to monitoring device101. In one embodiment, the packets of data may include the identification of monitoring device101and the identification of monitored unit102.

If, however, monitored unit102did not receive an acknowledgment at the appropriate time from monitoring device101at the expected frequency, then, in step503, monitored unit102determines if the time that monitored unit102has not received the acknowledgment exceeds a time threshold, e.g., three seconds.

If the time that monitored unit102has not received the acknowledgment does not exceed the time threshold, then, in step501, monitored unit102determines if it received an acknowledgment at the next appropriate time from monitoring device101at the next expected frequency according to the algorithm, e.g. frequency hopping table, stored in memory119.

If, however, the time that monitored unit102has not received the acknowledgment does exceed the time threshold, then, in step504, monitored unit102enters the locate mode of operation from monitoring device101. In step505, monitored unit102transmits packets of data at an increased rate at expected frequencies according to an algorithm, e.g., frequency hopping table, stored in memory119. For example, monitored unit102may transmit packets of data at expected frequencies every 1 second during the monitoring mode of operation. During the locate mode of operation, monitored unit102may transmit packets of data at expected frequencies every 200 milliseconds.

In step506, monitored unit102determines if it received a signal to exit the locate mode of operation from monitoring device101. If monitored unit102does not receive a signal to exit the locate mode of operation from monitoring device101, then, in step505, monitored unit102transmits packets of data at an increased rate at expected frequencies according to an algorithm, e.g., frequency hopping table, stored in memory119. If, however, monitored unit102does receive a signal to exit the locate mode of operation from monitoring device101, then, in step507, monitored unit102exits the locate mode of operation.

It is noted that method500may include other and/or additional steps that, for clarity, are not depicted. It is noted that method500may be executed in a different order presented and that the order presented in the discussion ofFIG. 5is illustrative. It is further noted that certain steps in method500may be executed in a substantially simultaneous manner.

FIG.6—Method for Locating Monitored Unit in the Locate Mode of Operation

FIG. 6is a flowchart of one embodiment of the present invention of a method600for locating monitored unit102in the locate mode of operation.

In step602, the user of monitoring device101may scan over a 360 degree field with monitoring device101.

In step603, monitoring device101transmits a signal to monitored unit102at the expected time and frequency using the algorithm stored in memory107to enter the locate mode of operation. In step604, monitoring device101determines if it received a packet of data at the appropriate time and at the expected frequency from monitored unit102.

If monitoring device101did not receive a packet of data from monitored unit102at the appropriate time and at the expected frequency, then, in step603, monitoring device101transmits a signal to monitored unit102at the expected frequency using the algorithm stored in memory107to enter the locate mode of operation.

If, however, monitoring device101did receive a packet of data from monitored unit102at the appropriate time and at the expected frequency, then, in step605, monitoring device101determines if it received a valid identification. As stated above, each time monitored unit102communicates with monitoring device101, monitored unit102may transmit a packet of data that includes the identification of a monitoring device101.

If the identification is not valid, then, in step606, monitoring device101ignores the received packet of data. The packet of data may have been intended for another monitoring device101.

If, however, the identification is valid, then, in step607, monitoring device101transmits an acknowledgment to monitored unit102at the expected frequency determined by the algorithm stored in memory107.

In step608, monitoring device101measures the strength of the received packet of data. In step609, monitoring device101determines the direction of the signal using digital compass105.

In step610, monitoring device101creates a polar plot, which is displayed on display106, indicating both the signal strength and direction of the received signal.

In step611, monitoring device101determines if the user of monitoring device101exits the locate mode of operation. In one embodiment, the user of monitoring device101may exit the locate mode of operation by inputting to monitoring device101, such as by button(s)/switch(es)109, a command to exit the locate mode of operation.

If the user does not exit the locate mode of operation, then, in step604, monitoring device101determines if it received a packet of data at the anticipated time and at the expected frequency from monitored unit102.

If, however, the user did exit the locate mode of operation, then, in step612, monitoring device101transmits a signal to monitored unit102to exit out of the locate mode of operation. In step613, monitoring device101returns to the monitoring mode of operation.

It is noted that method600may include other and/or additional steps that, for clarity, are not depicted. It is noted that method600may be executed in a different order presented and that the order presented in the discussion ofFIG. 6is illustrative. It is further noted that certain steps in method600may be executed in a substantially simultaneous manner.

FIG. 7illustrates an embodiment of the present invention of tamper sensor124(FIG. 1) including an infrared reflection mechanism to detect tampering of monitored unit102.

Referring toFIG. 7,FIG. 7illustrates tamper sensor124comprising an infrared emitter701and an infrared detector702. Tamper sensor124may be located on a surface of monitored unit102. For example, infrared emitter701and infrared detector702may be located on the side of monitored unit102touching the surface of an object, e.g., skin of a child. Monitored unit102may be configured to periodically generate a sequence of pulses on emitter701and detect the strength of the reflections of the emitted pulses from the surface of the object on detector702. The intensity of the returned reflections may correlate the distance monitored unit102is located from the surface of the object, e.g., skin of the child. The infrared reflection mechanism may detect tampering of monitored unit102as explained below in conjunction withFIG. 8.

FIG.8—Method for Detecting Tampering of Monitored Unit

FIG. 8is a flowchart of one embodiment of the present invention of a method800for detecting the tampering of monitored unit102using the infrared reflection mechanism ofFIG. 7.

Referring toFIG. 8, in conjunction withFIGS. 1 and 7, in step801, monitored unit102determines if the intensity of the reflections is less than a threshold. As stated above, detector702may be configured to detect the intensity of the infrared signals reflected off the surface of an object, e.g., skin of a child, that were emitted from emitter701.

If the intensity of the reflections is less than a threshold, then monitored unit102continues to determine if the intensity of the reflections is less than a threshold in step802.

If, however, the intensity of the reflections is equal to or greater than the threshold, then, in step802, monitored unit102transmits an indication to monitoring device101that monitored unit102has been tampered with. In step803, an indication, e.g., alarm, is outputted by monitored unit102. For example, an alarm may be outputted via beeper122or a speaker (not shown) on monitored unit102.

In step804, monitored unit102enters the locate mode of operation. It is noted that the locate mode of operation is discussed above and that the description will not be repeated herein for the sake of brevity.

It is noted that method800may include other and/or additional steps that, for clarity, are not depicted. It is noted that method800may be executed in a different order presented and that the order presented in the discussion ofFIG. 8is illustrative. It is further noted that certain steps in method800may be executed in a substantially simultaneous manner.

FIG.9—Method for Requesting the User of Monitored Unit to Return to Base

FIG. 9is a flowchart of one embodiment of the present invention of a method900for requesting the user of monitored unit102to return to base, i.e., return to a designated place such as home.

Referring toFIG. 9, in conjunction withFIG. 1, in step901, monitoring device101receives an input to indicate to a particular monitored unit102to return to base. For example, monitoring device101may receive an input from the user of monitoring device101to indicate to a particular monitored unit102to return to base via button(s)/switch(es)109. Return to base may refer to returning to a designated site such as home for a child.

In step902, monitoring device101transmits a signal to monitored unit102, selected by the user of monitoring device101, indicating to return to base.

In step903, monitored unit102receives the transmitted signal from monitoring device101indicating to return to base.

In step904, monitored unit102outputs an indication to the user of monitored unit102to return to base. For example, an indication to return to base may be outputted via beeper122or a speaker (not shown) on monitored unit102.

It is noted that method900may include other and/or additional steps that, for clarity, are not depicted. It is noted that method900may be executed in a different order presented and that the order presented in the discussion ofFIG. 9is illustrative. It is further noted that certain steps in method900may be executed in a substantially simultaneous manner.

FIG.10—Method for Deactivating a Selected Monitored Unit

FIG. 10is a flowchart of one embodiment of the present invention of a method1000for deactivating a selected monitored unit102.

Referring toFIG. 10, in conjunction withFIG. 1, in step1001, monitoring device101receives an input to deactivate a selected monitored unit102. For example, monitoring device101may receive an input from the user of monitoring device101to deactivate a selected monitored unit102via button(s)/switch(es)109.

In step1002, monitoring device101transmits a signal to monitored unit102, selected by the user of monitoring device101, to deactivate the selected monitored unit102.

In step1003, monitored unit102receives the transmitted signal from monitoring device101.

It is noted that method1000may include other and/or additional steps that, for clarity, are not depicted. It is noted that method1000may be executed in a different order presented and that the order presented in the discussion ofFIG. 10is illustrative. It is further noted that certain steps in method1000may be executed in a substantially simultaneous manner.

Although the system, computer program product and method are described in connection with several embodiments, it is not intended to be limited to the specific forms set forth herein; but on the contrary, it is intended to cover such alternatives, modifications and equivalents, as can be reasonably included within the spirit and scope of the invention as defined by the appended claims. It is noted that the headings are used only for organizational purposes and not meant to limit the scope of the description or claims.