Patent Publication Number: US-8981925-B2

Title: System, method, and apparatus for detecting wireless devices

Description:
FIELD 
     This invention relates to the field of wireless and more particularly to a system for detecting wireless devices. 
     BACKGROUND 
     There are many situations when it is either not desired or not legal to utilize certain types of wireless communications. One good example is in the corrections environment, where the correctional institution forbids wireless communication by inmates because such communications are difficult or impossible to monitor and/or control. Law enforcement entities monitor telephone conversations conducted by inmates within correctional facilities for various reasons. The telecommunications equipment available for use by detainees within the corrections environment meet various requirements of governments and police by monitoring and/or recording telephone conversations as needed. 
     Cellular technology has progressed in form and size to a point that inmates in the corrections environment find ways to hide and smuggle cellular phones into corrections facilities. These phones are then used by inmates to circumvent the required monitoring and/or recording and are often used to communicate amongst themselves to coordinate unauthorized or dangerous activities within the corrections facility. 
     In correctional facilities, inmates are limited to a small number of individuals that they are permitted to call by way of an approval process. These often include family members, lawyers, and friends. All such calls take place in a very controlled environment, facilitating monitoring and recording, as necessary and legal. Normally, inmates are not permitted to make calls to certain individuals such as judges, jury members, witnesses, known accomplices, etc., to prevent harassing or other unwanted calls. Some correctional facilities also restrict the time of day and length of calls. Such monitoring is typically computer controlled at the correctional facility and/or at remote locations, at times, includes human monitoring and/or control. Additionally, certain laws and privacy norms prohibit recording of certain conversations such as conversations between an inmate and his/her attorney. 
     The penetration of, for example, cellular phones into many correctional facilities has become alarming. Imagine the harm that results in a purported killer having a smuggled cellular phone and calling judges and jury members every night with threats if he is convicted; or being able to continue with unlawful activity through the use of a cellular phone. Yet, cellular phones still find their way into such institutions and are well hidden. To avoid detection and to extend battery life, often the cellular phones are powered completely off when not in use, thereby not emitting any type of radio frequency signal until the inmate desires to make a call. Such devices are so small that they are easily hidden and, because there is no radio frequency emissions when powered off, such devices cannot be detected by radio frequency sweeps of the inmate areas (e.g. cells, common areas, etc.). 
     In the past, attempts at detecting cellular activity within correctional facilities typically consisted of fixed antenna systems, in which, antenna are strategically located throughout the correctional facility and the radio frequency bands used by cellular phones are monitored, reporting detection to a central location. Such systems require an expensive, fixed infrastructure within the correctional facility and only determine that a cellular phone is in use, being incapable of pinpointing the actual user. 
     Other systems utilize one or more fixed antenna within the facility that terminate the unwanted cellular calls, acting as the cellular phone network, thereby making it difficult or impossible to initiate a call from a cellular phone within the facility. As with the prior attempts, this too does not pinpoint the actual inmate making the call. Furthermore, because signals from this system may extend beyond the prison walls, this system is capable of inadvertently blocking a valid call which could be disastrous if such a call was an emergency call. There are also questions as to whether such a system would be approved for operation by government agencies such as the FCC in the United States. Similarly, jamming devices are available to prevent connections between these cellular phones and the cellular network/towers, but it is also difficult to assure that such jamming devices will not interfere with legitimate calls, especially emergency calls and, again, there are questions related to approval by government agencies. 
     Another prior attempt to find cellular phones includes portable detection devices that monitor and detect radio frequency emissions in the cellular range. Such devices have been found to be less reliable because, in a prison environment, often there is a tight inmate communication system (e.g. signaling by making certain noises, etc.) that alerts the inmate who is using the cellular phone that a guard is coming in sufficient time as to power down and/or hide the phone before the guard can pinpoint the radio frequency signal. The use of phone (electronics) sniffing dogs faces similar issues when used as the primary means of cell phone detection. 
     What is needed is a system that will detect and pinpoint radio frequency usage for locating and confiscating of unauthorized communications equipment and report any detected devices. 
     SUMMARY 
     The basic system provides for radio frequency detection of a device within a specific range of a body worn device. Upon detection of a targeted radio frequency signal, the body worn device communicates to an infrastructure to alert of the presence of the radio frequency signal. The user and/or location of the body worn device is/are revealed and the source of the radio frequency signal is readily determined for confiscation of the offending device. Other features include locating/tracking of the body worn device (and wearer) detection of tampering with or removal of the body worn device, detection of cloaking of the body worn device (e.g. submerging in water or covering with aluminum foil, etc.), and various internal diagnostics. 
     Although there are many applications of the described body worn device(s), one exemplary use is within correctional facilities. As noted above, various communications devices are often smuggled into correctional facilities and are easily hidden. The use of such devices is not allowed, but still happens. By equipping at least a subset of the inmate population with the disclosed body worn devices, the correctional facility staff is provided the ability to locate any covered radio frequency emitting device within the correctional facility. Guards and staff are alerted when the inmate wearing the body worn device or someone close to that inmate uses a targeted wireless device, such as a cellular phone. Once alerted, the guards know the exact identification of the inmate and, therefore, the location of the illegal device enabling confiscation of the illegal device. 
     In one embodiment, a system for detecting radio frequency emitting devices is disclosed including at least one base station. The base station includes a base station processor and a base station transceiver which is operatively coupled to the base station processor. A plurality of body worn devices is provided. Each body worn device has a processor, a transceiver operatively coupled to the processor, a radio frequency detector operatively coupled to the processor, and a source of power for providing operational power to the processor, the transceiver, and the radio frequency detector. Software running on the processor of the body worn device communicates with the radio frequency detector and, if a target radio frequency is detected by the radio frequency detector, the software initiates a communication from the transceiver to the base station transceiver indicating that the target radio frequency was detected. Upon receipt of the communication indicating that the target radio frequency was detected, software running on the base station processor determines the offending body worn device and signals an alert. 
     In another embodiment, a method of detecting a radio frequency emission is disclosed. The method includes monitoring a predetermined radio frequency (or frequencies) at a body worn device and, if the predetermined radio frequency of at least a predetermined radio frequency strength is detected, transmitting a signal from a transmitter of the body worn device to a receiver of a base station, the signal including an identification of the body worn device. Upon receiving the signal, the base station issues an alarm indicative of the predetermined radio frequency and the identification of the body worn device. 
     In another embodiment, a computer-based system for detecting radio frequency transmissions is disclosed includes a body worn device. The body worn device has a processor, a wireless transceiver communicatively coupled to the processor, and a radio frequency transmission detector interfaced to the processor. The radio frequency transmission detector detects any radio frequency transmission of at least one frequency and at a power level above a predetermined threshold for each of the at least one frequency. The computer-based system also includes a base station that has a base station processor and a base station transceiver. The base station transceiver is wirelessly coupled to the wireless transceiver of the body worn device, thereby providing a wireless communication channel between the processor of the body worn device and the base station processor. Software running on the processor monitors the radio frequency transmission detector and, upon detection of any of the at least one frequency exceeding a corresponding threshold of the predetermined threshold for each of the at least one frequency, the processor formats a signal (e.g. prepares a packet) and sends the signal (e.g. packet) through the wireless communication channel to the base station processor. Software running on the base station processor monitors the base station transceiver and upon detection of the signal, the software running on the base station processor signals an alarm (e.g., displays a message, sounds an alarm, etc). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which: 
         FIG. 1  illustrates a schematic view of a typical wireless communication system and body worn device. 
         FIG. 2  illustrates a block diagram of a body worn device. 
         FIG. 3  illustrates a block diagram of a second body worn device. 
         FIG. 4  illustrates a perspective view of an exemplary body worn device. 
         FIG. 5  illustrates a block diagram of communications used to initialize a body worn device. 
         FIG. 6  illustrates a block diagram of a body worn device detecting wireless activity. 
         FIG. 7  illustrates a block diagram of a body worn device detecting wireless activity and location derivation of the body worn device. 
         FIG. 8  illustrates an exemplary user interface showing the status of a body worn device. 
         FIG. 9  illustrates an exemplary user interface showing the status of a body worn device when the body worn device has been cloaked. 
         FIG. 10  illustrates an exemplary user interface showing the status of a body worn device upon detection of unauthorized communications. 
         FIG. 11  illustrates a flow chart of an exemplary body worn device controller. 
         FIG. 12  illustrates a second flow chart of a second exemplary body worn device controller. 
         FIG. 13  illustrates a third flow chart of a typical transmission by a body worn device controller. 
         FIG. 14  illustrates a flow chart of an exemplary base station controller. 
         FIG. 15  illustrates a schematic view of a typical computer-based body worn device system. 
         FIG. 16  illustrates a schematic view of an exemplary system of a base station. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures. 
     The described system pertains to a collection of hardware devices for monitoring the location and environment of any target person. Throughout this description, the target person is typically a detained person such as an inmate in a correctional facility, but there is no restriction to any particular type of target person, nor that the target be a human being, in that the described body worn device functions the same for any type of movable object. The described system is equally applicable to any other type of scenario. For example, the target person is a teen child and the body worn device is worn by the teen child to monitor, for example, cell phone usage while driving. 
     For simplicity purposes, the following description uses, as an example, the inmate as the target person. In general, depending upon security and policies at a prison, the population (inmates) is not allowed to communicate with those outside the prison without using approved forms of communication that are easily monitored by prison authorities. In such, the inmate population is not allowed to use pagers, cellular phones, cordless phones, wireless Internet access, etc., to communicate with anybody, within or outside of the prison. Attempts to keep devices capable of such communications out of the hands of inmates has proved ineffective, in that inmates have long periods of time to think of ways to smuggle communications devices into the prison and, to hide those devices once the devices are within the prison. This is further exacerbated by potential corruption within the prison staff and guards. 
     Referring to  FIG. 1 , a schematic view of a typical wireless communication system  5  is shown, in which a body worn device  40  is present. The overall structure, communication paths, and connection relationships shown are one example of a wireless communication system  5  and are not meant to limit this disclosure in any way. Many different organizations, protocols, operating frequencies (bands), and architectures are anticipated and all of such are included here within. The system is intended to operate with any known network  10 , including all known and future wireless networks  10  or point-to-point systems. Wireless networks, are for example, the cellular phone network (e.g., GSM, CDMA, AMPS, etc.), wireless Internet (e.g. WiFi-802.11x, etc.), etc. Point-to-point systems include Bluetooth, citizen band radios, walkie-talkie radios, and any other licensed or unlicensed forms of wireless communications. These communication system enable any number of end-user terminals  12 / 14 / 15  (e.g. cellular phones  12 , personal computers  14 , tablets  15 , etc.) to communicate wirelessly with each other or through a network such as the cellular network  10  as shown to other devices, either within the network  10  or external (e.g. land-line phones, etc.). As known in the industry, the network  10  often consists of one or more devices such as cellular towers, repeaters, wireless network adapters, etc., which are not shown for brevity reasons. 
     Throughout this description, a cellular network  10  is used as an example, though such is not to be interpreted as limiting in any way. In the example of the cellular network  10 , each device  12 / 14 / 15  communicates with cellular towers (not shown for brevity reasons) utilizing a pre-defined protocol and a pre-defined frequency or set of frequencies. As known in the industry, cellular networks  10  are assigned a set of frequencies in which they are allowed to operate (in the US the assignment is made by the Federal Communications Commission or FCC), and, depending upon the protocol, the frequencies are allocated for certain parts of the protocol such as signaling (e.g. indicating the desire to make a connection), voice communications, data communications, etc. It is also known, based upon the protocol, how to process/avoid collisions (e.g. two cellular phones  12  attempt to initiate a call at the same time), how to handle varying distances from the cellular towers (e.g. measuring signal strength and signaling a request for increases or decreases in power output), and how to hand off a cellular phone from one cellular tower to the next, etc. 
     Whatever the wireless communications being used, every device  12 / 14 / 15  must, at some time, emit a radio frequency signal  20  that is then hopefully received by one or more receivers within the network  10 . Although it is desired to communicate such radio frequency signals  20  directly to the network  10  (or other device in a point-to-point system), the laws of physics do not cooperate and the radio frequency signal  20  radiates in multiple directions from an antenna, the antenna being within (or external to) the transmitting device  12 / 14 / 15 . For example, when the cellular phone  12  communicates to the cellular network  10 , some portion of the radio frequency signal  21  reaches an antenna within the body worn device  40 . Likewise, when the cellular network  10  communicates to the cellular phone  12 , some portion of the radio frequency signal  23  also reaches an antenna within the body worn device  40 . In this way, the body worn device  40  receives some portion of the radio frequency energy emitted from any device  12 / 14 / 15  or network  10  that is within range (e.g. the signal strength of the radio frequency is sufficient for the body worn device to detect). 
     Within the body worn device  40  is circuitry  50 / 50 A (see  FIGS. 2 and 3 ) that implement the various features of the wireless system including some or all of radio frequency detection, communications, tamper detection, positioning, and powering of the above. 
     Referring to  FIG. 2 , a block diagram of the body worn device circuitry  50  is shown. The various communications paths  62 / 63 / 64 / 65 / 66 / 67  are examples and any number, type, and directionality of communications paths are anticipated to accomplish the functionality described here within. In some embodiments, a bus architecture is used to implement the communications paths  62 / 63 / 64 / 65 / 66 / 67 , while in other embodiments, direct connections, serial links, input output pins/ports, etc., are used to signal between the various subsystems  60 / 70 / 80 / 90  as known in the industry. 
     The body worn device circuitry  50  includes a source of power  98 . It is well known how to power such devices ranging from simple body worn devices such as watches to more complicated devices that are often body worn such as cellular phones, to specialized worn devices such as house-arrest tracking devices. Any source(s) of power are anticipated, including, but not limited to, batteries, rechargeable batteries, solar cells, radio frequency parasitic extraction, capacitors, super capacitors, fuel cells, etc., including combinations of such. The source of power  98  includes circuitry to condition and regulate the power which is then distributed to the various subsystems  60 / 70 / 80 / 90  by power distribution  99  which are any known conductor  99  as used in the industry, including, but not limited to, wires, printed circuit paths, etc. In some embodiments, the source of power  98  further includes circuitry to control charging as well as a connection or interface to a source of charging power. 
     The radio frequency detection subsystem  80 / 80 A is interfaced to the processor  60 . The processor controls the operation of the radio frequency detection subsystem  80 / 80 A by sending commands  65  to the radio frequency detection subsystem  80 / 80 A and receiving status and data back  66  in a similar manner (e.g. signal frequency and strength). The radio frequency detection subsystem  80 / 80 A includes one or more antenna  82 / 82 A as needed, either internal or external to an enclosure  41  of the body worn device  40 . Although, for completeness, two radio frequency detectors  80 / 80 A are shown, each detecting a specific frequency range or band of radio frequency energy, any number of radio frequency detectors  80 / 80 A are anticipated, each having as many antenna  82 / 82 A as needed to properly detect the targeted radio frequency or radio frequency spectrum. For example, in some embodiments, there is a single radio frequency detector  80  having a single antenna  82 . In another exemplary embodiment, there is a single radio frequency detector  80  having two antennas  82 / 82 A which are switched or mixed as known in the industry. In another exemplary embodiment, there are two radio frequency detectors  80 / 80 A, each having one antenna  82 / 82 A. Again, any number of radio frequency detectors  80 / 80 A with any number of antenna  82 / 82 A are anticipated with any type of antenna. 
     In some embodiments, the radio frequency detection subsystem  80  operates independently of the controller  60 , notifying the controller  60  of the detection of any of the targeted radio frequencies (e.g. cellular band frequencies, etc.). In some embodiments, the controller  60  performs some of the radio frequency detection, such as setting or sweeping the detection frequency and comparing the received radio frequency power levels at each frequency to a predetermined acceptable value. For example, the controller  60  instructs the radio frequency detector  80  to monitor three specific frequency, such as 900 MHz, 1.8 GHz and 1.9 Ghz, and then reads back a signal strength from the radio frequency detector  80 , comparing the signal strength to an internal threshold, signaling an alert (as will be discussed with  FIG. 14 ) if the threshold is exceeded. There are many divisions of the detection functionality anticipated and the disclosed system is not limited in any way to any particular implementation of the disclosed functionality. In some embodiments, there is a threshold for each frequency or range of frequencies; while in other embodiments there is a single threshold that applies to all frequencies. In some embodiments, the radio frequency detector analyzes the radio frequency signals to determine the type of signal in addition to the signal strength (e.g. is it a random radio frequency signal or is it encoded with cellular packets?). 
     The tamper detection subsystem  90  is also interfaced to the processor  60 . The processor  60  controls the operation of the tamper detection subsystem  90  by sending commands and/or signals to the tamper detection subsystem  90  and receiving status and data back in a similar manner  67  (e.g. intact or “device removed from body,” etc.). It is anticipated that the body worn device  40  is issued to a particular individual (e.g. inmate) and is to be locked onto that person by, for example, a leg cuff, arm cuff, neck cuff, belt, etc. Although the body worn device  40  is secured to the person and not easily removed, it is important that any tampering with the body worn device  40  be detected (and reported). There are many methods of detecting tampering or removal of a body worn device  40  known in the industry, all of which are anticipated and included here within. For example, in some embodiments, a conduction path fully encircles the body appendage to which the body worn device  40  is attached such that, if the strap  41  (see  FIG. 4 ) is cut, the circuit opens and the open circuit is detected by the tamper detection system  90 . This is a somewhat simple method that is used as an example; in that, a clever person can expose the conductor in two locations, attach an end of a wire to the conductor in each location, then cut through the strap in between the two locations without detection. In some embodiments, more elaborate measurements are used to detect the added resistance (or change in resistance) of the external wire. In some embodiments, an optical light pipe connected at both ends to the body worn device  40  encircles the appendage and a particular wavelength(s) of light or an encoded light wave signal is emitted into one end of the light pipe. If the signal is detected at the other end, then it is believed that no tampering has occurred, but if the signal is not detected, then tampering is detected and an appropriate alert is transmitted as will be described. There are many types of tamper detection devices anticipated including the above and/or any other type of tamper detection including, but not limited to, motion sensors and accelerometers (e.g. if no movement is detected for a long period of time it is assumed that the body worn device  40  has been removed from the body). 
     In some embodiments, the tamper detection subsystem  90  also includes intrusion detection to determine if the housing  41  (see  FIG. 4 ) around the electronics has been penetrated. Again, there are many ways to detect such intrusion as known in the industry, all of which are included here within. For example, a simple method includes the detection of light within the housing  41  (see  FIG. 4 ). Normally, there is no light being that the housing  41  is made of a non-light transmitting material and completely sealed with no openings, but when the housing  41  is compromised, light is allowed to enter the housing  41  and triggers the tamper detection system  90 . In other embodiments, there is an internal detector that detects one or more materials or physical state normally present in the atmosphere (e.g. change in pressure, humidity, oxygen, nitrogen, etc.) and the housing  41  is either evacuated or filled with some other gas (e.g. helium). In this, normally, the detector measures little or no presence of the material, but when the housing  41  is cut, atmosphere enters the housing, the material is detected, and the tamper detection system  90  is triggered. 
     The body worn device circuitry  50  communicates with the land based system (e.g. base stations  110 ) through a wireless transceiver  70 , preferably having an antenna  74 , though in some embodiments, the transceiver  70  utilizes the antenna  82  used in radio frequency detection through, for example, a splitter or antenna switch (not shown). The wireless transceiver  70  is interfaced to the processor  60  and the processor  60  communicates with and controls the operation of the wireless interface and transceiver  70  by sending commands  62  and data  63  to the wireless transceiver  70  and receiving status and data back in a similar manner  63 . Because such transceivers often consume significant power, in some embodiments, the processor  60  has an enable interface  64  to power down the transceiver  70  (or any other subsystem) when not in use. Any appropriate signaling protocol is anticipated, as transmission collisions with other body worn devices  40 , lost packets, out-of-order packets, noise, etc., must be overcome. The data and signaling is modulated onto a radio frequency using any known modulation format such as frequency modulation, amplitude modulation, pulse code modulation, pulse width modulation, etc. 
     It is anticipated that the transceiver  70  be any type of transceiver, operating over any known frequency or group of frequencies, any known power level(s), and either half-duplex or full-duplex. When the transceiver  70  is half-duplex, the processor  60  controls whether the transceiver is receiving or it is transmitting by a mode control  62 . 
     Data is transferred between the processor  60  and the transceiver  70  in any way known in the industry including, but not limited to, shared memory (not shown), serial transfer, parallel transfer, any combination, etc. In a preferred embodiment, though not required, data from the processor  60  is encrypted before transmission. In such, the data is either encrypted by instructions running on the processor  60 , or, in some embodiments, by an encryption module  72  within or external to the transceiver  70 . Also in a preferred embodiment, though not required, data from the base station  110  (see  FIG. 6 ) is encrypted before transmission. In such, the encrypted data is received by the transceiver  70 , and then the encrypted data is either decrypted by instructions running on the processor  60 , or, in some embodiments, by a hardware encryption module  72  within or external to the transceiver  70 . 
     Any band, frequency, wavelength, set of wavelengths, protocols, protocol stacks are anticipated for use by the transceiver  70  (and transceiver  935  in  FIG. 16 ). There are many protocols and protocol options that provide various transmission capabilities to improve reliability of communications, reduction or elimination of transmission errors, and/or efficiencies in both spectrum usage as well as power consumption. For example, especially in systems that include heartbeat transmissions, it is known to provide each body worn device  40  with a predetermined back-off period or, instead, a random back-off period is created by the controller  60  such that timing of transmissions are controlled to reduce collisions between multiple body worn devices  40 . In such, for example, if there are 600 body worn devices  40  and each emits a heartbeat every hour, it is preferred that the heartbeat transmissions are distributed either sequentially or randomly over that hour, such that, for example, during any given minute, 10 of these body worn devices  40  transmit heartbeats and, preferably, these 10 transmissions are distributed either sequentially or randomly over that minute, to further reduce collisions. 
     In some embodiments, a piezoelectric or other sound emitting device  99  is included. The sound emitting device  97  emits a sound as an audible alert when an event such as tampering or a targeted RF signal is detected. The audible alert from the sound emitting device is used to augment the wireless delivery of the alert information or as an alternative. For example, if a wireless communication fails, the audible alert is initiated. 
     In some embodiments, a clock or timekeeper  59  is included, either as a subsystem of the controller  60  or a separate, discrete timing device  59  that is interface to the controller  60 . In such embodiments, the body worn device  40  has the ability to record the time and/or date of any event and to transmit the time and/or date to the base station  110  along with any alert and/or heartbeat transmission. 
     Referring to  FIG. 3 , a block diagram of body worn device circuitry  50 A with Global Positioning is shown. The various communications paths  62 / 63 / 64 / 65 / 66 / 67 / 68 / 69  are examples and any number, type, and directionality of communications paths are anticipated to accomplish the functionality described here within. In some embodiments, a bus architecture is used to implement the communications paths  62 / 63 / 64 / 65 / 66 / 67 / 68 / 69 , while in other embodiments, direct connections, serial links, input output pins/ports, etc., are used to signal between the various subsystems  60 / 70 / 80 / 90 / 94 . 
     The body worn device circuitry  50 A includes a source of power  98 . It is well known how to power such devices ranging from simple body worn devices such as watches to more complicated devices that are often body worn such as cellular phones, to specialized worn devices such as house-arrest tracking devices. Any source(s) of power are anticipated, including, but not limited to, batteries, rechargeable batteries, solar cells, radio frequency parasitic extraction, capacitors, super capacitors, fuel cells, etc., including combinations of such. The source of power  98  includes circuitry to condition and regulate the power which is then distributed to the various subsystems  60 / 70 / 80 / 90 / 94  by conductors  99  which are any known conductor  99  as used in the industry, including, but not limited to, wires, printed circuit paths, etc. In some embodiments, the source of power  98  further includes circuitry to control charging as well as a connection or interface to a source of charging power. 
     The radio frequency detection subsystem  80 / 80 A is interfaced to the processor  60 . The processor controls the operation of the radio frequency detection subsystem  80 / 80 A by sending commands  65  to the radio frequency detection subsystem  80 / 80 A and receiving status and data back  66  in a similar manner (e.g. signal frequency and strength). The radio frequency detection subsystem  80 / 80 A includes one or more antenna  82 / 82 A as needed, either internal or external to an enclosure  41  (see  FIG. 4 ) of the body worn device  40 . Although, for completeness, two radio frequency detectors  80 / 80 A are shown, each detecting a specific frequency range or band of radio frequency energy, any number of radio frequency detectors  80 / 80 A are anticipated, each having as many antenna  82 / 82 A as needed to properly detect the targeted radio frequency or radio frequency spectrum. For example, in some embodiments, there is a single radio frequency detector  80  having a single antenna  82 . In another exemplary embodiment, there is a single radio frequency detector  80  having two antennas  82 / 82 A which are switched or mixed as known in the industry. In another exemplary embodiment, there are two radio frequency detectors  80 / 80 A, each having one antenna  82 / 82 A. Again, any number of radio frequency detectors  80 / 80 A with any number of antenna  82 / 82 A are anticipated with any type of antenna. 
     The tamper detection subsystem  90  is also interfaced to the processor  60 . The processor  60  controls the operation of the tamper detection subsystem  90  by sending commands and/or signals to the tamper detection subsystem  90  and receiving status and data back in a similar manner  67  (e.g. intact or “device removed from body,” etc.). It is anticipated that the body worn device  40  is issued to a particular individual (e.g. inmate) and is to be locked onto that person by, for example, a leg cuff, arm cuff, neck cuff, belt, etc. Although the body worn device  40  is secured to the person and not easily removed, it is important that any tampering with the body worn device  40  be detected. There are many methods of detecting tampering or removal of a body worn device  40  known in the industry, all of which are anticipated and included here within. For example, in some embodiments, a conduction path fully encircles the body appendage to which the body worn device  40  is attached such that, if the strap  42  (see  FIG. 4 ) is cut, the circuit opens and is detected by the tamper detection system  90 . This is a somewhat simple method that is used as an example; in that, a clever person can expose the conductor in two locations, attach ends of a wire to the conductor in each location, then cut through the strap  42  in between the two locations without detection. 
     In some embodiments, a method of determining the body worn device&#39;s proximity to the body is used to determine if the device has been removed. Some methods known in the industry for detecting proximity include continuity sensors and mechanical switches that determine if the device is no longer in contact with the body. Such continuity sensors and mechanical switches are prone to false positives and nuisance alerts and can be defeated more easily than other methods. 
     In some embodiments, more elaborate measurements are used to detect the added resistance (or change in resistance) of the external wire. In some embodiments, an optical light pipe embedded in a strap encircles the body part to which the body worn device  40  is attached and a specific wavelength an encoded light wave signal is emitted or periodically emitted into one end of the light pipe. If the same signal is detected at the other end, then it is believed that no tampering has been done, but if the signal is not detected, then tampering is detected. 
     In some embodiments, the tamper detection subsystem  90  also includes intrusion detection to determine if the housing  41  around the electronics has been penetrated. Again, there are many ways to detect such intrusion as known in the industry, all of which are included here within. For example, a simple method includes the detection of light within the housing  41 . Normally, there is no light being that the housing  41  is completely sealed with no openings, but when the housing  41  is penetrated, light is allowed to enter and triggers the tamper detection system  90 . In other embodiments, there is an internal detector that detects one or more materials or physics typically present in the atmosphere (e.g., atmospheric pressure, humidity, oxygen, nitrogen, etc.) and the housing  41  is either evacuated or filled with some other gas (e.g. helium). In this, normally, the detector measures little or no presence of the material, but when the housing  41  is cut, atmosphere enters the housing  41 , the material is detected, and the tamper detection system  90  is triggered. 
     There are many tamper detection mechanisms known in the industry, all of which are anticipated for use with the body worn device  40 . Further examples include the use of a motion sensor or accelerometer to determine if the device experiences long periods of time with no motion, indicating that the device has been removed and has been placed somewhere in a static mode. 
     The body worn device  40  communicates with the land based system (e.g. base stations  110 ) through a wireless device  70 , preferably a transceiver having an antenna  74 , though in some embodiments, the transceiver  70  utilizes the antenna  82  used in radio frequency detection through, for example, a splitter or antenna switch (not shown). The wireless transceiver  70  is interfaced to the processor  60  and the processor  60  communicates with and controls the operation of the wireless interface and transceiver  70  by sending commands  62  and data  63  to the wireless transceiver  70  and receiving status and data back in a similar manner  63 . Because such transceivers often consume significant power, in some embodiments, the processor  60  has an enable interface  64  to power down the transceiver  70  (or any other subsystem such as the positioning subsystem  94 ) when not in use. 
     Throughout this description, the wireless device  70  is referred to as a transceiver  70 , which is the preferred form of communications with the base station  110 . The wireless transceiver  70  transmits a wireless signal to the base station and receives a wireless signal back, either on the same band/wavelength/frequency or a different band/wave/frequency utilizing any protocol or stack of protocols. For example, if a signal/message from the transceiver  70  of the body worn device  40  is not received and acknowledged by the transceiver  935  (see  FIG. 16 ) within a protocol timeout period or if it is received with errors and negatively acknowledged, the signal/message is retransmitted. In embodiments in which the wireless device  70  is a transmit-only device, there is no acknowledgement possible and no mechanism to determine if the transmission succeeded. 
     It is anticipated that the transceiver  70  be any type of transceiver, operating over any known frequency or group of frequencies, using any known modulation technique, at any known power level(s), and either half-duplex or full-duplex. When the transceiver  70  is half-duplex, the processor  60  controls whether the transceiver is receiving or it is transmitting by a mode control  62 . 
     Data is transferred between the processor  60  and the transceiver  70  in any way known in the industry including, but not limited to, shared memory (not shown), serial transfer, parallel transfer, any combination, etc. In a preferred embodiment, though not required, data from the processor  60  is encrypted before transmission. In such, the data is either encrypted by instructions running on the processor  60 , or, in some embodiments, by an encryption module  72  within or external to the transceiver  70 . Also in a preferred embodiment, though not required, data from the base station  110  (see  FIG. 6 ) is encrypted before transmission. In such, the encrypted data is received by the transceiver  70 , and then the encrypted data is either decrypted by instructions running on the processor  60 , or, in some embodiments, by a encryption module  72  within or external to the transceiver  70 . 
     In the embodiment of  FIG. 3 , positioning capability is included. For example, a Global Positioning Satellite Receiver  94  is interfaced to the processor  60 . In such, the processor controls the Global Positioning Satellite Receiver  94  operation by sending commands  69  to the Global Positioning Satellite Receiver  94  and receiving status and data  68  from the Global Positioning Satellite Receiver  94  (e.g. latitude and longitude). Typically, the Global Positioning Satellite Receiver  94  has a specialized antenna  96  or array of antenna  96 . Any known type of positioning system is anticipated for use with the body worn device  40 . 
     Referring to  FIG. 4 , a perspective view of an exemplary body worn device  40  is shown. In this example, the body worn device  40  is a collar  40 , such as a leg collar  40 , arm collar  40 , or neck collar  40 , while in other embodiments; the body worn device  40  is of slightly different forms for attachment to the body in different ways such as by a belt-like system. In the exemplary body worn device  40  shown in  FIG. 4 , some or all of the electronics  50 / 50 A are located within an enclosure  41  that is made as part of the strap  42  or affixed to the strap  42  so as to resist removal and/or intrusion. The strap  42  is locked closed after placing around the person&#39;s appendage, for example by a non-removable lock  44 . In some embodiments, the lock  44  is part of the enclosure  41 . In some embodiments, the lock includes a one-way closure system in which, the strap  42  is tightened around an appendage by capturing more of the strap  42  through the one-way closure system, then cutting off any excess strap  42 . In some embodiments, especially those with electronics, conductors, and/or light pipes within the strap  42 , the strap  42  is of fixed length and locks into the enclosure  41 , completing the tamper detection circuit. In the industry of inmate or release monitoring (e.g. house arrest), it is well known how to attach similar devices to a person and to detect tampering and/or removal, all of which are anticipated and included here within. 
     Although any form of attachment mechanism is anticipated for the body worn device  40 , in some embodiments, the attachment mechanisms and enclosure  41  are designed to prevent removal under normal wear and impact that often occurs during the wearing of such device such as, during exercise, walking, running, etc. Furthermore, in some embodiments, the attachment mechanisms and enclosure  41  are designed to resist penetration by substances that normally contact the wearer such as during showering, rain, etc. Although any suitable material is anticipated, it is preferred that at least the surface of the strap  42  and/or enclosure  41  be made from a hypoallergenic material such as Santoprene, being that the body worn device  40  will be worn for long periods of time. It is also preferred that the strap  42  be made from materials that will not significantly stretch, even when heated. Stretching is not desired because, in some cases, stretching enables easy removal without detection of tampering. In some embodiments, the enclosure  41  is made of an impact resistant polycarbonate that is rugged, tamper resistant, and seals the electronics from the surrounding environment. 
     As previously described, in some embodiments, the body worn device  40  includes a perimeter detection loop  45  that consists of a conductor  45  (either light or electrical signal) that helps detect tampering. For example, if the strap  42  is cut, the perimeter detection loop  45  is broken and a tamper signal is sent from the transceiver  70  of the body worn device  40  to the base station  110 . 
     In some embodiments, an RFID  46  is mounted in/on the enclosure  41  and/or in the strap  42 . This optional RFID (or other readable mechanism such as a bar code, QR code, etc.) is available for use to facility systems for many uses such as head counts, usage accounting, commissary expense charges, etc. 
     Referring to  FIG. 5 , a block diagram of communications used to initialize a body worn device  40  is shown. For example, a body worn device  40  is issued  100  to a user (e.g. an inmate), and user data  103  is captured and/or linked to the body worn device  40 . In this, either the body worn device  40  has an embedded serial number that is then linked to the user data  103  or some part of the user data  103  is uploaded and stored in the non-volatile memory  825  (see  FIG. 15 ) of the body worn device  40 . In this way, either the serial number or that part of the user data  103  is later used as part of the communications between the body worn device  40  and the base station  110  to identify the user (e.g. inmate). Once the data  103  is captured/linked and the issuance  100  is complete, this body worn device  40  is enabled and tested  102 . For example, communications are established and test messages sent/received to insure proper operation. If the enablement and testing  102  is successful, the body worn device  40  is then locked  104  around, for example, the user&#39;s (e.g., inmate&#39;s) appendage. 
     The software operating within the body worn device  40  is also updated, as necessary, through the wireless interface. 
     In some embodiments, the condition of the battery in the body worn device  40  is also reported during some or all transmissions. In some embodiments, diagnostics or self-tests are performed during initialization and/or periodically and any anomalies are reported through the wireless interface. 
     Referring to  FIG. 6 , a block diagram of a body worn device  40  detecting wireless activity is shown. In this example, an offending device  12  (e.g. a cellular phone  12 ) is activated to establish a call through the cellular network  10 , and for example, through the plain-old-telephone system (POTS)  11  to another person (not shown). Note that call records  13  are created to record the call, origination, destination, length of call, etc. In this example, the origination is recorded as the cell phone  12  at a certain geographic area (e.g. Manhattan). Such records are useful in after-the-fact tracking, but are not very helpful in finding the offending device  12 . In this scenario, the system  50 / 50 A within the body worn device  40  detects the radio frequency signal  21  from the offending device  12 . Upon detection, the system  50 / 50 A compiles a message including, for example, the frequency of the radio frequency signal  21 , the signal strength of the radio frequency signal  21 , an identification of the body worn device  40  (and/or the user or inmate), the time and/or date of the event, and, if available, the latitude and longitude of the body worn device  40 . This message is optionally encrypted then transmitted from the transceiver  70  of the body worn device  40 . The message is then received by either or both of an optional repeater  100  and/or a base station  110  where the message is optionally decrypted and the data is analyzed to determine the user (e.g. inmate) associated with the body worn device  40 , the type of offender  12 , and, optionally the location of the body worn device  40  and, therefore, the location of the user (e.g. inmate). An exemplary alert report screen that is displayed after reception of such a message by the base station  110  is shown in  FIG. 8 . 
     Although not required, the transmission of the signal/message is performed using an end-to-end protocol that assures proper reception of the signal/message. All forms of reliable transmissions are anticipated, including automatic retransmission of unacknowledged attempts, retransmission of signals/messages that were received with errors, error correcting protocols, etc. In such embodiments, once an event occurs, transmission is continually attempted until it is properly received at the base station or, in some embodiments, until it is deemed futile to continue such transmissions. In some embodiments, if a second event occurs during the transmission and/or retransmission of a first event is underway, the second event (and subsequent events as storage permits) is captured in memory (e.g. nonvolatile memory  825  (see  FIG. 15 ) until a second (and subsequent) signal/message is sent. 
     In some embodiments, the system  50 A within the body worn device  40  includes a positioning system  94  and the message includes, for example, the latitude and longitude of the body worn device  40 . In some embodiments, the system  50  within the body worn device  40  lacks a positioning system  94  and/or positioning signals are not being received and the message cannot include a location of the body worn device  40 . In such, triangulation is used to determine the location of the body worn device  40  as is described along with  FIG. 7 . 
     Referring to  FIG. 7 , a block diagram of a body worn device  40  detecting wireless activity is shown in which a location of the body worn device is determined through triangulation. In this example, an offending device  12  (e.g. a cellular phone  12 ) is activated to establish a call through the cellular network  10 , and for example, through the plain-old-telephone system (POTS)  11  to another person (not shown). Note that call records  13  are created to record the call, origination, destination, length of call, etc. In this example, the origination is recorded as the cell phone  12  at a certain geographic area (e.g. Manhattan). Such records are useful in after-the-fact tracking, but are not very helpful in finding and confiscating the offending device  12 . In this scenario, the system  50  within the body worn device  40  detects the radio frequency signal  21  from the offending device  12 . Upon detection, the system  50  compiles a message including, for example, the frequency of the radio frequency signal  21 , the signal strength of the radio frequency signal  21 , an identification of the body worn device  40  (and/or the user or inmate). In this example, the system  50  within the body worn device  40  has no positioning system  70 , so there is no latitude and longitude of the body worn device  40  encoded into the message. This message is optionally encrypted then transmitted from the transceiver  70  of the body worn device  40 . The message is then received by a plurality of repeaters  100 A/ 100 B and/or a base station  110  where the message is optionally decrypted and the data is analyzed to determine the user (e.g. inmate) associated with the body worn device  40 , and the type of offender  12 . In this example, because the body worn device  40  has no capability of reporting a location, the location of the body worn device  40  and, therefore, the location of the user (e.g. inmate) must be derived from the radio frequency signal as it is received by the plurality of repeaters  100 A/ 100 B and base stations  110 . It is known how to determine the origin of a radio frequency signal through triangulation of the radio frequency signal. Triangulation is typically performed by measuring the time at which the stations  100 A/ 100 B/ 110  receive the signal (e.g. if the repeater  100 A receives the signal first and the repeater  100 B and base station  110  receive the signal at the same time a few milliseconds later, the body worn device is closer to repeater  100 A and midway between the repeater  100 B and the base station  110 ). Triangulation systems are known to accurately translate these reception times into latitude and longitude values given the latitudes and longitudes of each of the triangulating receivers  100 A/ 100 B/ 110 . In some triangulation systems, signal strength is used either separately or in conjunction with signal timing to determine the location of the body worn device  40 . 
     An exemplary alert report screen that is displayed after reception of such a message and triangulation by the base station  110  is shown in  FIG. 8 . 
     The following examples use a fictitious inmate, John Doe, as an example of a person assigned and wearing a body worn device  40 . This does not imply that the disclosed inventions are in any way limited to prisons or correctional facilities. 
     Referring to  FIG. 8 , an exemplary user interface  200  showing the status of a body worn device  40  is shown. In this example, data pertaining to the person  202  includes an inmate name (John Doe), an inmate number (12345678), and a home location (Cell 8). Data  204  pertaining to the body worn device  40  assigned to this inmate includes a description of the device (Leg BWD) and a code (34AF2BAA) which is, for example, a serial number of this body worn device  40 . Next, status  206  of the assigned body worn device  40  is shown/displayed, including an indication that the device has been enabled, a condition of the battery, whether the body worn device  40  has detected any radio frequency transmissions (No Transmissions Detected), whether the body worn device  40  detects the cellular network (Detected), and the latitude and longitude of the body worn device  40 . Note that, in some embodiments, more or less information is included. 
     Referring to  FIG. 9 , an exemplary user interface  200  showing the status of a body worn device  40  when the body worn device has been cloaked is shown. In this example, data pertaining to the person  202  includes an inmate name (John Doe), an inmate number (12345678), and a home location (Cell 8). Data  204  pertaining to the body worn device  40  assigned to this inmate includes a description of the device (Leg BWD) and a code (34AF2BAA) which is, for example, a serial number of this body worn device  40 . Next, status  206 A of the assigned body worn device  40  is shown, including an indication that the device has been enabled, a condition of the battery, a time/date of the event, whether the body worn device  40  has detected any radio frequency transmissions (No Transmissions Detected), whether the body worn device  40  detects the cellular network (Detected), and the latitude and longitude of the body worn device  40 . In this case, the device is not detecting any signal from a cellular network (e.g. local tower) and, therefore, it is believed that the body worn device  40  has been cloaked by, for example, submerging the body worn device  40  in water or encapsulating the body worn device  40  in metal foil, etc. In an alternate embodiment, as will be described, heartbeat monitors are implemented to make sure each body worn device  40  is operating and hasn&#39;t been cloaked. For example, the base station  110  polls each body worn device  40  every 30 seconds and if no response is received, the status of the body worn device  40  that hasn&#39;t responded is updated and appropriate alarms are issued. In an alternate heartbeat embodiment, the timing is performed in both the base station  110  and the body worn device  40 . In this, the body worn device  40  transmits a heartbeat signal or packet at a scheduled interval such as every 30 seconds. The base station  110  has a timer for each body worn device  40  that is set to an interval just longer than this schedule interval, for example 40 seconds. Each time the base station  110  receives the heartbeat signal/packet, the timer is reset to the interval (e.g. 40 seconds) and never expires. If the heartbeat is not received within the allotted time (e.g. 40 seconds), the status is updates and alarms issued as appropriate. Since there are reasons besides cloaking that a single heartbeat transmission might get lost, it is anticipated that more complicated algorithms are used to manage heartbeats and to perform other communication tests when one is missed before initiating status changes and/or alarms. Note that, in some embodiments, more or less information is included. 
     Referring to  FIG. 10 , an exemplary user interface  200  showing the status of a body worn device  40  upon detection of unauthorized communications  21  is shown. In this example, data pertaining to the person  202  includes an inmate name (John Doe), an inmate number (12345678), and a home location (Cell 8). Data  204  pertaining to the body worn device  40  assigned to this inmate includes a description of the device (Leg BWD) and a code (34AF2BAA) which is, for example, a serial number of this body worn device  40 . Next, status  206 B of the assigned body worn device  40  is shown, including an indication that the device has been enabled, a condition of the battery, a time/date of the event, whether the body worn device  40  has detected any radio frequency transmissions (UNAUTHORIZED Transmissions Detected), whether the body worn device  40  detects the cellular network (Detected), and the latitude and longitude of the body worn device  40 . In this example, the associated body worn device  40  has detected an unauthorized radio frequency transmission. Note that, in some embodiments, more or less information is included. 
     The user interface shown is an overly simplified interface for understanding purposes. It is anticipated that the Location (latitude and longitude) be used to pin point the user (e.g. inmate) within a floor map of the building to quickly find that user (e.g. inmate) and confiscate the infringing transmitting device. Furthermore, other information regarding the radio frequency signal  21  that was detected by the body worn device  40 , when available, are displayed, for example, frequencies and signal strength for each frequency received, durations of signals, etc. In some embodiments, such information is further analyzed to classify the transmission device so that after confiscation, it is known whether the correct device has been confiscated. For example, if a cellular signal is detected but, after searching, only a tablet computer  15  is found, authorities know to keep searching until they find a cellular phone  12 . 
     Referring to  FIG. 11 , a flow chart of an exemplary body worn device controller  60  is shown. When power is initially applied to the body worn device  40 , the processor  60  initializes  400  and then initializes communications  402 . For example, communications with a base station  110  is initialized  402 . The system repeatedly attempts to communicate with the base station  110  until a connection is detected  404 , at which time the body worn device identification is established  406 . This is performed by either reading a hard or soft serial number of the body worn device  40  and transmitting that serial number to the base station  110  or by determining a unique serial number by the base station  110  and transmitting that serial number to the body worn device  40  where the serial number is then stored in non-volatile memory  825 . Next, a user (e.g. inmate) is assigned  408  to that serial number so that, any future communications containing that serial number will be identifiable with that user (e.g. inmate). Now the radio frequency receiver/detector  80  is enabled  412  to monitor radio frequency transmissions in the local of the body worn device  40 . 
     Until reset, the body worn device system  50  continuously loops, each time through the loop accessing the radio frequency receiver/detector  80  to determine if the cellular network  10  is present  420  (e.g. is the body worn device being cloaked?), accessing the tamper detection circuit  90  to determine if tampering has been detected  430 , and accessing the radio frequency receiver/detector  80  to determine if there has been any unauthorized radio frequency transmission  440 . If the cellular network  10  is not present  420 , a signal or packet indicating that this particular body worn device  40  has been cloaked or masked  450  is sent to the base station  110 . If tampering has been detected  430 , a signal or packet indicating that this particular body worn device  40  has been tampered (e.g. removed, broke)  460  is sent to the base station  110 . If there has been any unauthorized radio frequency transmission  440 , a signal or packet indicating that this particular body worn device  40  has detected such radio frequencies is transmitted  470  is sent to the base station  110 .  FIG. 13  shows an exemplary flow for transmitting these signals or packets while  FIG. 14  shows an exemplary flow in the base station  110  for processing receipt of these signals or packets. 
     Referring to  FIG. 12 , a flow chart of a second exemplary body worn device controller  60  is shown. This flow is similar to that shown in  FIG. 11 , except implementing a heartbeat monitor to determine if the body worn device  40  has been cloaked. When power is initially applied to the body worn device  40 , the processor  60  initializes  400 . Next, communication is initializes  402 , perhaps with a base station  110 . The system repeatedly attempts to communicate with the base station  110  until a connection is detected  404 , at which time the body worn device identification is established  406 . This is performed by either reading a hard or soft serial number of the body worn device  40  and transmitting that serial number to the base station  110  or by determining a unique serial number by the base station  110  and transmitting that serial number to the body worn device  40  where the serial number is then stored in non-volatile memory  825 . Next, a user (e.g. inmate) is assigned  408  to that serial number so that, any future communications containing that serial number will be identifiable with that user (e.g. inmate). For embodiments with a heartbeat method of detecting cloaking, the heartbeat timer is initialized  410 . There are many ways to implement heartbeat monitoring, this being one of them. The basic operation has two timers, one in the base station and one in the body worn device  40 . The timer in the base station is set somewhat longer than one or two periods of the timer in the body worn device  40 , for example, the timer in the base station is set to 40 second and the timer in the body worn device  40  is set to 30 seconds (or 15 seconds to receive two heartbeats before the base station timer expires). Each time the heartbeat is received by the base station  110 , the base station timer is reset (e.g. to 40 seconds). If no heartbeats signals/packets are receive within the base station timer interval and the base station timer expires, it is declared that the body worn device  40  has lost communications and is possibly being cloaked. 
     Next the radio frequency receiver/detector  80  is enabled  412  to monitor radio frequency transmissions in the local of the body worn device  40 . 
     Until reset, the body worn device system  50  continuously loops, each time through the loop accessing the radio frequency receiver/detector  80  to determine if the cellular network  10  is present  420  (e.g. is the body worn device being cloaked?), accessing the tamper detection circuit  90  to determine if tampering has been detected  430 , accessing the radio frequency receiver/detector  80  to determine if there has been any unauthorized radio frequency transmission  440 , and checking the heartbeat timer in the body worn device  40  to determine if a heartbeat needs to be transmitted  442 . If the cellular network  10  is not present  420 , a signal or packet indicating that this particular body worn device  40  has been cloaked or masked  450  is sent to the base station  110 . If tampering has been detected  430 , a signal or packet indicating that this particular body worn device  40  has been tampered (e.g. removed, broke)  460  is sent to the base station  110 . If there has been any unauthorized radio frequency transmission  440 , a signal or packet indicating that this particular body worn device  40  has detected such radio frequencies is transmitted  470  is sent to the base station  110 . If a heartbeat needs to be transmitted  442 , the heartbeat signal/packet is transmitted and the heartbeat timer is reset to schedule the next heartbeat transmission  444 .  FIG. 13  shows an exemplary flow for transmitting these signals or packets while  FIG. 14  shows an exemplary flow in the base station  110  for processing receipt of these signals or packets. 
     Referring to  FIG. 13 , a second flow chart of a typical transmission by a body worn device controller  60  is shown. In this, if available, the signal strength  510  and the signal frequency  520  are read from the radio frequency detector  80 . Next, communications is attempted with the base station until a connection is established  530 . Once communication is established with the base station  530 , the signal or packet(s) is transmitted  540 , typically including the reason for the transmission (e.g. heartbeat, radio frequency detected, loss of cellular signal, tamper detected, battery low, etc.), the identification (serial number) of the body worn device  40 , optionally, the frequency and/or signal strength of the radio frequency signal, optionally the duration of the radio frequency signal, and optionally the latitude and longitude of the body worn device  40 . Next, to assure that the packet/signal was received by the base station  110 , the body worn device software waits for an acknowledgement  450 . If an acknowledgement is received  450 , the transmission process is complete (e.g. returns to the loops of  FIG. 11  or  FIG. 12 . If an acknowledgement is not received  450  (e.g. within an expected time frame), the transmission process is repeated from step  530 . 
     The simplified example of transmitting between the body worn device  40  and the base station  110  as described is but an example as reliable data transmission is well known and many methods and protocols exist to perform such transmissions. The exemplary program flows described here within are but examples and one skilled in the art will readily be able to produce a transmission mechanism capable of such communication. 
     Referring to  FIG. 14 , a flow chart of a base station controller  900  (see  FIG. 16 ) is shown. The described flow generally operates on a processor within, for example the base station  110 . As known in the industry, this control flow is often implemented as an application that runs, along with other applications, on a dedicated or multi-purpose computer system, an example of which is shown in  FIG. 16 . The described application is threaded to monitor one single body worn device  40 , though it is anticipated that many body worn devices  40  are present and monitored by a similar application or multiple instantiations of this exemplary process flow. 
     The following relates to communications with one or many body worn device  40 . When the application starts running, general initialization is performed  600 , communications is initialized  602 , and then communication with the target body worn device(s)  40  is established  604 , looping until communication is made. Once communications are established  604 , the identification of the body worn device  40  is read or set  606  (as described with  FIGS. 11 and 12 ), establishing an identifier (e.g., serial number) of the body worn device  40  and a user (e.g. inmate) is assigned to that identifier  608 . In systems in which there is a heartbeat, a heartbeat timer is initialized  610  as described previously. 
     Now a loop is entered. The first step of the loop is to determine if a packet or signal has been received  615  from the body worn device  40 . If no packet or signal has been received  615 , the heartbeat timer is checked for expiration  680  (e.g. the timer expires if no heartbeats are received within the heartbeat timer interval). If the heartbeat timer expired  680 , an appropriate indication/alarm is made  685  (e.g. message display, flashing light, etc.) and the loop continues. 
     If a packet or signal has been received  615  from the body worn device  40 , a determination of the type of packet or signal is made. If the packet/signal indicates that the body worn device  40  has lost presence of a cellular network signal  620  (e.g. it is cloaked), an appropriate indication/alarm is made  625  (e.g. message display, flashing light, etc.) and the loop continues. 
     If the packet/signal indicates that the body worn device  40  has been tampered with  630  (e.g. it has been removed from the user/inmate), an appropriate indication/alarm is made  635  (e.g. message display, flashing light, etc.) and the loop continues. 
     If the packet/signal indicates that the body worn device  40  detected an unauthorized radio frequency transmission  640 , an appropriate indication/alarm is made  645  (e.g. message display, flashing light, etc.—hopefully alerting staff/guards to confiscate the offending device) and the loop continues. 
     If the packet/signal indicates that the body worn device  40  is sending a heartbeat signal  650 , the heartbeat timer is reset  655  and the loop continues. 
     If none of the above (e.g., an unknown packet/signal was received), an error is recorded and appropriate actions taken to restore the system to level of operation such as a complete reset, etc. 
     Referring to  FIG. 15 , a schematic view of an exemplary system  50 / 50 A of the body worn device  40  is shown. The example system represents an exemplary processor-based system housed in a body worn device  40 . Although, throughout this description, a processor-based system is described, it is known to implement the same or similar functionality in a system of logic or analog components providing similar functionality in an equivalent system. The power subsystem  98  (e.g., battery, power management, charge control, etc.) is known in the art and is not shown for clarity reasons. 
     The exemplary system of the body worn device  50  is shown in its simplest form, having a single processor  60  (e.g., controller, microcontroller, microprocessor, etc.). Many different computer architectures are known that accomplish similar results in a similar fashion and the present invention is not limited in any way to any particular processing element  60 . In exemplary system of the body worn device  50 , a processor  60  executes or runs stored programs that are generally stored for execution within a memory  820 . The processor  60  is any processor, for example an Intel 80C51 single chip processor or the like. The memory  820  is connected to the processor by a memory bus  815  and is any memory  820  suitable for connection with the selected processor  60 , such as SRAM, DRAM, SDRAM, RDRAM, DDR, DDR-2, etc. Also connected to the processor  60  is a system bus  830  for connecting to peripheral subsystems. In general, the non-volatile memory  825  is interfaced to the processor  60  through the system bus  830  and is used to store programs, executable code and data persistently. Examples of persistent storage include core memory, FRAM, flash memory, etc. 
     In embodiments in which Global Positioning is included, a positioning system  94  (e.g. GPS) is interfaced to the processor  60  by the system bus  830 . In such, the processor controls the positioning system  94  operation by sending commands to the positioning system  94  over the system bus  830  and receiving status and data back in a similar manner (e.g. latitude and longitude). 
     The Radio Frequency Detection subsystem  80  is also interfaced to the processor  60  by the system bus  830 . In such, the processor controls the operation of the Radio Frequency Detection subsystem  80  by sending commands to the Radio Frequency Detection subsystem  80  over the system bus  830  and receiving status and data back in a similar manner (e.g. signal frequency and strength). 
     The tamper detection subsystem  90  is also interfaced to the processor  60  by, for example, the system bus  830  (or through an input/output port, etc.). In such, the processor controls the operation of the tamper detection subsystem  90  by sending commands to the tamper detection subsystem  90  over the system bus  830  and receiving status and data back in a similar manner (e.g. intact or “device removed from body,” etc.). 
     The body worn device  50  communicates with the land based system (e.g. base stations  110 ) through a wireless interface and transceiver  70 . The wireless interface and transceiver  70  is also interfaced to the processor  60  by, for example, the system bus  830  (or through an input port, etc.). In such, the processor communicates with and controls the operation of the wireless interface and transceiver  70  by sending commands and data to the wireless interface and transceiver  70  over the system bus  830  and receiving status and data back in a similar manner. 
     Although a specific architecture is shown connecting the various subsystems  94 / 80 / 90 / 825 / 70  to the processor  60 , any known interface is anticipated including, but not limited to, parallel bus architectures, serial bus architectures, parallel/serial bus architectures, input/output port interfaces, Inter-Integrated Circuit links (I 2 C—two-wire interface), etc. 
     In some embodiments, a sound emitting device  97  is interfaced to the processor  60 , in this example, through an output pin, though any form of connection is anticipated, including an interface to the bus  830 . Any type of sound emitting device  97  is anticipated such as a piezoelectric element, speaker, electromechanical vibrator, indirect sound emitter, etc. In some embodiments, the sound emitting device is driven directly by the processor  60 ; while in other embodiments, the sound emitting device includes driver circuitry such as an oscillator and/or power amplifier. 
     Referring to  FIG. 16 , a schematic view of an exemplary system of the base station  110  is shown. The example system represents an exemplary processor-based system. Although, throughout this description, a processor-based system is described, it is known to implement the same or similar functionality in a system of logic or analog components providing similar functionality in an equivalent system. 
     The exemplary base station  110  as shown in its simplest form has a single processor  900  (e.g., controller, microcontroller, microprocessor, etc.). Many different computer architectures are known that accomplish similar results in a similar fashion and the present invention is not limited in any way to any particular processing element  900 . In exemplary systems, a processor  900  executes or runs stored programs that are generally stored for execution within a memory  920 . The processor  900  is any processor. The memory  920  is connected to the processor by a memory bus  915  and is any memory  920  suitable for connection with the selected processor  900 , such as SRAM, DRAM, SDRAM, RDRAM, DDR, DDR-2, etc. Also connected to the processor  900  is a system bus  930  for connecting to peripheral subsystems. In general, the secondary storage  925  is interfaced to the processor  900  through the system bus  930  and is used to store programs, executable code and data persistently. Examples of secondary storage  925  include semiconductor disks, rotating media, hard disks, CD-ROM, DVD-RW, CD-RW, flash memory, etc. 
     The base station  110  communicates with the body worn devices  40  through a wireless interface and transceiver  935 . The wireless interface and transceiver  935  is preferably interfaced to the processor  900  by, for example, the system bus  930  but alternately interfaces through an input port, etc. The processor  900  communicates with and controls the operation of the wireless interface and transceiver  935  by sending commands and data to the wireless interface and transceiver  935  over the system bus  930  and receiving status and data back in a similar manner. 
     For completeness, optional input and output devices  980 / 990  are shown such as a display  980  and a keyboard  990 , though many different back end architectures are anticipated including one or more processors/computer systems, linked together for distribution and/or redundancy reasons along with a variety of input and output devices optionally including any or all of card readers, badge readers, indicator lights, lighting control systems, audible alarms, interfaces to cell locking systems, interfaces to door locking systems, camera systems, motion detection systems, door open/closed detection systems, etc. 
     In some embodiments, the base station  110  also includes tamper detection  985  similar or different from the tamper detection subsystem  90  of the body worn device  40 . In such, intrusion into the base station  110  and/or relocation of the base station outside of a given allowed area is determined, recorded, and/or alerted. For example, in one embodiment, the tamper detection  985  includes a positioning device (e.g., GPS) that constantly monitors the location of the base station  110 . If the base station  110  is moved to a new location that is outside of a predetermined area, alerts are made such as transmitting an alert to other base stations  110  or repeaters  100 , locking/encrypting data, etc. Other types of base station tamper detectors  985  are anticipated, including, but not limited to, motion sensors, accelerometers, etc. It is also anticipated that the base station  110  be physically affixed to furniture to reduce chances of removal. 
     In some embodiments, the base station  110  (and/or the repeaters  100 ) is/are mobile devices, allowing for the base station  110  to be portable and carried by guards, staff, etc. 
     Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result. 
     It is believed that the system and method as described and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.