Abstract: An alarm communication device and a method for mutual recognition between a first alarm unit and a second unit connected therebetween by a public switching unit is provided. The first alarm unit is connected to the public switching unit via at least one first communication line and the second unit is connected to the public switching unit via at least one second communication line. The method includes the steps of detecting a ring signal at the first alarm unit, detecting a caller identification (ID) signal provided by the public switching unit, determining a caller ID number from the caller ID signal, matching the caller ID number with at least one predetermined number and when the caller ID number is matched to one of the at least one predetermined number associated with the second unit, executing a predetermined procedure associated with the matched at least one predetermined number.

Abstract: Desired audio information intermittently present in a first audio signal is communicated over a communications medium by generating a first communications signal in the communications medium when the desired audio information is present in the first audio signal, the first communications signal representing the first audio signal encoded as blocks of communications data according to a predetermined code. A second communications signal is received from the communications medium. The received second communications signal is processed to produce processed blocks of communications data. A metric representing the validity of a plurality of the processed blocks of communications data is then determined, and a second audio signal is generated from the plurality of processed blocks of communications data when the metric is within a predetermined range.

Abstract: A telecommunity alarm system having a plurality of security surveillance modems that can be connected to a telecommunication network via an analog or digital subscriber terminal port, the security surveillance modems forming a group of a predetermined size. The security surveillance modems each have a first memory for storing telephone numbers of the other modems in the group, a second memory for identifying the particular modem and a programmable control unit. The modems are designed to dial automatically, in the event of an alarm, the other security surveillance modems belonging to the group and signal the alarm status.

Abstract: An apparatus for detecting the discharge of a firearm and transmitting an alerting signal to a predetermined location. The invention provides for detection circuitry having: (1) a microphone for detecting pre-set sensitivity levels, (2) a measuring means for measuring acoustic energy generated from the discharge of the firearm, resulting in acoustic energy information, (3) transferring means for transferring the acoustic energy information to a digital signal processor, which converts the acoustic energy information into digital format, resulting in digitized binary codes, (4) an analyzing means for comparing the digitized binary codes contained in the digital signal processor with a set of predetermined criteria, (5) a verification process, and (6) an alerting means for transmitting an alerting signal to a predetermined location in the event the digitized binary codes match the set of predetermined criteria.

Abstract: A security structure-opening assembly (12) for use in unlocking a locked structure (24) comprising: a radio frequency receiver (16) formed to detect radio frequency signals on a radio frequency; an actuator (20) coupled to the receiver (16) and formed for coupling to one of a security structure lock assembly (25) and an unlocking mechanism (22A) for a security structure lock assembly (25) at a position by-passing any authorized user input device (23); the receiver (16) being responsive to detected signals to actuate the actuator (20) and produce unlocking of the lock assembly (25). At progressively higher levels of security, the radio signal is analyzed by a private line detector circuit (30), a digital burst detector circuit (31) and a decoder circuit (32).

Abstract: The present invention provides an independent supervised communications network which interfaces with an existing cellular telecommunications network by utilizing locally unused cellular frequencies to report information from a premise to a central monitoring facility. This invention utilizes an input device associated with the premise for providing one or more status messages to a transceiver module. The transceiver module may be a modified cellular telephone which is operable in one of three modes; supervision, event and wait. The cellular phone modifications are primarily software changes which provide a logic routine for scanning and selecting an available forward control channel based on a comparison of preselected criteria with measured characteristics and determining a reverse control channel corresponding to the selected forward control channel.

Abstract: A home alarm system for use by an authorized user while in the home, manual input commands to the system being required by the user as events around the home might occur for proper system operation. The system includes a programmable microcomputer having a specific preprogrammed operating logic and a multi-key control panel operably connected to the microcomputer. By manually depressing an arming key, the microcomputer is activated to initiate a first time delay. This would typically be done by a user at the ring of a doorbell or upon hearing strange noises and the like. Unless a multi-key disarming code is entered before the end of the first timing delay, a warning signal is activated and continues for a second preprogrammed time delay. Again, unless the disarm code is timely entered before the end of the second time delay, a very loud siren or other wide area broadcast alarm signal is activated.

Abstract: A telephone operated electrical switch for selectively energizing an electrical load in response to dialing of a predetermined telephone number. The electrical load may be the exterior light fixture of a dwelling, and the switch assembly may be configured to automatically flash the light on and off in response to the occupant dialing "9-1-1", so as to assist emergency response personnel in locating the dwelling.

Abstract: A modem is equipped with both a conventional telephone line interface for attaching to a wired telephone jack and a special interface for connecting to a cellular telephone. The modem interacts with the cellular telephone in accordance with a special protocol, wherein signals of the protocol are derived directly from the conventional modem signals used to interact with the wired telephone jack. No high voltage signals need pass between the modem and cellular telephone. Substitution of the cellular telephone for the wired telephone jack is transparent to the software used to operate the modem. Aside from a connection cable, no special hardware is required between the cellular telephone and modem.

Abstract: A system and method for communicating information concerning the status of inmates to callers and automatically notify victims registered with the system at a registered electronic address when the status of a specified inmate has changed. The notifications to the electronic address of the registered victim will continue at spaced predetermined intervals until either the registered victim responds with a registered personal identification number or a predetermined time period measured from the initial time notification elapses.

Abstract: A data processing section controls a line connecting section, data transferring section, speech output section and console control section to process and input/output data for responding/reporting. The data processing section analyzes data received from the data base of a supervision and control system which is a connection object via the data transferring section, and effects a process according to the result of analysis, linkage information and message content set from the console via the console control section. The data processing section creates message data of a response message indicating the operating condition of the supervision and control system and supplies the same to the speech output section and supplies a speech message created in the speech output section to a public communication line via the line connecting section.

Abstract: The present invention relates to a device to be connected to any standard alarm control panel for the verification of the actuated alarm. This device includes one or two printed circuit board(s), preferably one, which is located within a house or integrated within the alarm control panel. On this board, which is referred to as an "Interface Module", are located an alarm panel interface for receiving the alarm signal from the alarm control panel, a specially programmed microcontroller, a non-volatile memory, an audio selecting matrix connected to at least one remote microphone unit, and a public switch telephone network (PSTN) interface, which is connected to a telephone line, through which the Interface Module communicates with the control station.

Abstract: A remote vehicle disabling and distress indicator system for a motor vehicle that is activated by an external telephone call or internally by one of two switches. The telephone call sends a signal received by a modular telephone stored in the vehicle that disables the vehicle by deactivating the ignition coil or substantially closing a fuel valve that controls fuel flow between the vehicle fuel tank and the vehicle engine. The signal also causes a distress sign at the top of the vehicle to be illuminated. In addition, the signal activates a tape machine that plays a prerecorded distress tape message through speakers that send a loud audible reproduction of the taped message internally and externally to the motor vehicle to attract the attention of any local population. The taped message may be any of a variety of messages, such as "HELP|", "CALL THE POLICE|", etc.

Abstract: This invention provides a new and improved emergency alarm system comprising a central control unit which is directly or indirectly connected to every other component of the emergency alarm system. The central control unit triggers and stops a visual alarm generator and an audio alarm generator, either simultaneously or separately, upon receiving signals from other components of the emergency alarm system. A portable control element and a signal-generating detection means are used for starting and stopping the central control unit, which in turn triggers a power supply means to cause a change, through the visual alarm generator, in color of a visible outdoor board and to commence, through the audio alarm generator, an alarm. A hidden sensing circuit can serve as the signal-generating detection means. The present invention also presents a method of application of said emergency alarm system.

Abstract: A wireless transceiver connects to a telephone line network terminal, in place of a disabled subscriber drop cable. A second wireless transceiver connects to customer premises wiring, typically at the network interface device and in place of the drop cable. The wireless transceivers preferably provide a cordless telephone type link. The second transceiver presents a standard telephone line appearance to the customer premises telephone wiring. Standard telephone station equipment, connected to the customer premises wiring in the normal manner, can make and receive telephone calls, as if still connected to a wire-line type telephone loop circuit.

Abstract: A method for monitoring a condition, such as the presence of electrical power, at a remote location and for generating a telephone call on to a telephone line that delivers to a central control unit notification of a change in the monitored condition in the form of a set of unique identifying signals. According to the method, the condition is monitored at the remote location and is sensed for changes in the condition from a first state to a second state. Responsive to a change in the condition to the second state, the telephone line is tested and a line availability signal generated. Responsive to indicia of line availability, the line is selectively seized.

Abstract: A method for handling alarm conditions from paging stations in a paging system is disclosed. The paging system includes a paging terminal, a plurality of paging stations, and a network manager. When a paging station has an alarm condition, the paging station forwards the alarm to the network manager, which in turn, compares the alarm with an alarm record for that paging station and determines whether or not that alarm is a higher priority than the previous alarms received from the paging station. If so, the network manager transmits a signal to the paging terminal to page the technician responsible for servicing that particular paging station. The technician is paged and dispatched to the paging station for service.

Abstract: A combination cordless telephone and premise-monitoring alarm system has a base unit, a cordless handset, and one or more remote alarm detectors. The alarm detectors can be generally either smoke detectors, motion detectors, or open-entry detectors. The base unit includes at least one interface for the public telephone network, and another interface for radio communication with the cordless handset. The base unit preferably also communicates with the remote alarm sensors across the same radio interface. The base unit includes telephone call circuitry to relay telephone calls between the public telephone network and the handset. The base unit also includes alarm processing circuitry to send an alarm warning to a central alarm-monitoring station in response to an alarm signal from a remote detector.

Abstract: An automatic transmission system of an emergency signal and a method thereof using a driver's brain wave which enables the police and hospitals, having a network with an earth station, to provide a proper and immediate rescue operation for those involved in an accident by transmitting an emergency signal derived from the driver's brain wave to the earth station via a global positioning system (GPS) satellite if a driver is in critical condition after the accident. The automatic transmission system of an emergency signal using a driver's brain wave includes a brain wave sensing block, an amplifier, an analog/digital converter, a memory, a microcontroller, and a transmission block.

Abstract: A sensing system including an optical receiver for receiving downstream optical signals and for converting the downstream optical signals to downstream electrical signals. An optical transducer impresses information in an upstream data signal onto upstream optical signals. At least one sensor responsive to an external stimulus provides sensor information signals. A processor receives the downstream electrical signals and establishes communication channels to at least one communication terminal providing communication information signals, and to the at least one sensor. The at least one terminal and the at least one sensor provide the communication and sensor information signals, respectively, to the processor which forwards the information signals to the optical transducer as the upstream data signal.

Abstract: A system for monitoring the status of mobile units includes a module and a local station. The module attaches to the mobile unit and includes a sensor and transmitter. The module transmits signals to a receiver at the local station. The signals can indicate shock, tampering, or theft. The receiver delivers the signal to a computer at the local station. The computer stores and analyzes the data. The computer includes a display, a keyboard, and a printer. The computer is programmed to present the data to the user and is fitted with an internal card to dial a monitoring station.

Abstract: A system is provided for monitoring a user in a user living area. The system includes a system controller and an activity detection subsystem. The activity detection subsystem monitors a daily living activity of the user and provides information representative of the daily living activity to the system controller. The system controller includes a control circuit which generates a control signal in response to the daily living activity information obtained by the activity detection subsystem. Control information from the system controller is applied by way of a control information communication channel both to the activity detection subsystem and to a remote monitoring site. The activity detection subsystem may be a system for determining the movement of the user around the home, medication compliance by the user, problems with usage of stoves or other potentially dangerous appliances, and selected auxiliary appliances.

Abstract: A voice system and method in which messages are stored as data files. One or more tags are associated with each file, which identify the mailboxes intended to receive the message contained in the file. An owner of a mailbox can transfer a message to another mailbox by changing the tag to designate a transferee-mailbox. This tag manipulation saves memory space because the message file is not copied into the transferee-mailbox, only a tag is changed. Time is also saved because no delay is imposed by a copying process.

Abstract: A vehicle responsive alert system includes a receiver for receiving a recognizable signal from a preselected vehicle; a control member, positioned at a location and operatively associated with the receiver for enabling the receiver upon the indication of a preselected event; and a response member operatively associated with the receiver for issuing a response when the receiver receives the signal, whereby the receiver is enabled upon the indication of the event and activates the response member upon receiving the signal.

Abstract: A universal method of trellis encoding signals mapped according to any signal constellation format involves constructing an encoder output table and a state transition table. The encoder output table defines the output symbol of an encoder given the input symbol and the present state of the encoder, while the state transition table defines the next state of the encoder given the present state of the encoder and the input applied to the encoder. The output table and the next state table are constructed with the objective of providing maximal distances between the branches of the trellis diagram without any regards for the shift register implementation of the code. Cyclic trellis-coded modulation is an example of such codes without feed-forward or feed-back shift register implementations, and with equal or better performance than "optimal" shift register trellis codes with 16 states or less.

Abstract: An alarm system for protecting premises comprises a fully integrated, alarm detecting cellular phone unit which is linked to various sensors in order to detect the sensor outputs. The cellular alarm unit includes, in addition to cellular phone functions, a formatter or processor for generating an emergency signal on detection of a sensor output, the emergency signal including information on the type of emergency detected. The unit is programmed to establish a cellular connection to a remote monitoring station. The connection is wireless at least from the premises to a local cell site. Once connection is established, the emergency signal is transmitted to the monitoring station via the local cell site.

Abstract: A channel interface unit for interconnecting a two-wire transmission path which transmits analog signals and a digital signal transmission path. The channel interface unit includes a digital interface unit coupled with the digital signal transmission path and producing digital signals based on digital signals received from the digital signal transmission path, a converter for converting the digital signals to analog signals, a filter for removing noise, produced by the converter, from the analog signals, a driver, coupled with the two-wire transmission path, for amplifying the filtered analog signals, and a power supply for providing regulated voltage to the driver.

Abstract: A channel interface unit for interconnecting a two-wire transmission path which transmits analog signals and a digital signal transmission path. The channel interface unit includes a digital interface unit coupled with the digital signal transmission path and producing digital signals based on digital signals received from the digital signal transmission path, a converter for converting the digital signals to analog signals, a filter for removing noise, produced by the converter, from the analog signals, a driver, coupled with the two-wire transmission path, for amplifying the filtered analog signals, and a power supply for providing regulated voltage to the driver The channel interface unit also includes a device for decreasing effective capacitance by modifying the output impedance of the driver.

Abstract: The present invention provides a simplified system for accommodating an alarm monitoring system to effectively communicate with a remote monitoring station by land lines or by a cellular communication channel. This is accomplished in a manner which reprograms the typical operation of an autotelephone dialer in combination with a particular authorization of a cellular interface. This combination results in a system which is reliable, cost effective, and which can be added to many existing alarm systems, which do not have a cellular capability.

Abstract: A remote-controlled anti-theft or theft-deterrent system and method, for motor vehicles, is disclosed which comprises a transmitting device, wherein the transmitting device is capable of transmitting data signals to at least two remote locations, a first receiving device for receiving the data signals transmitted from the transmitting device at a first of the at least two remote locations, a second receiving device for receiving the data signals transmitted from the transmitting device at a second of the at least two remote locations, a first control device associated with the first receiving device for processing the data representative of the data signals, wherein the first control device processes the data representative of the data signals and issues one of a disable signal and a re-enable signal to one of a vehicle's ignition system, a vehicle's fuel pump system and a vehicle's auxiliary equipment system one of instantaneously and after a time delay period, and a second control device associated with the

Abstract: A system for transmitting data between a subscriber site and at least one monitoring station, comprising a sensor circuit for generating data responsive to an event at the subscriber site, a first transmission circuit responsive to said sensor circuit and being operable to transmit data in packet form from the subscriber site to the monitoring station over a cellular digital packet data telecommunications network, a second transmission circuit responsive to said sensor circuit and being operable to transmit data from the subscriber site to the monitoring station over a second telecommunications network. A fault detect circuit is coupled to the first transmission circuit for continuously monitoring the operation of the first transmission circuit and the integrity of the cellular digital packet data telecommunications network. A control switch is coupled to the fault detect circuit and controlled thereby for automatically creating a signal path between the sensor circuit and the second transmission circuit.

Abstract: A multiprocessor alarm data processing system includes a database with identifying information for all the central stations and their subscribers who use the system. Several input processors receive alarm data from the central stations to identify subscribers incurring alarm events. The input processors generate event records for alarm data validated against the database. Several output processors are provided to process the event records to select the appropriate municipal authority and transmit thereto identifying information for a sucscriber incurring an alarm event. The processors may be switched between input and output processing for dynamic internal load shifting and redundant processing systems are provided for inter-system load sharing. A busy-out capable modem is provided to facilitate such inter-system load sharing.

Abstract: A simple, inexpensive device for automatically dialing an emergency number in response to a signal generated by a smoke alarm or other security system. The device includes a cam and cam follower, arranged in combination with an electrical switch connected to a telephone line, so that the motion of the cam follower causes the switch to create a dialing function without human intervention, and without electrical power, other than the dial-tone voltage from the telephone line.

Abstract: A personal assistance system and method for use with a cellular communication system operating over a cellular communication band and having a plurality of cell-sites. A transceiver transmits to the cell-sites a spread spectrum burst of pulses including a service request codeword indicating a request for service from a service provider. A proxy cell-phone, coupled to a preferred one of the cell-sites, originates a cellular call on the cellular communication system to a destination number of the service provider and on behalf of the transceiver to thereby create a cellular communication link between the transceiver and the service provider. A transceiver location feature provides the service provider with the geographic location of the transceiver.

Abstract: A 911 emergency response system that includes a location identification module, preferably in solid state circuit form, associated with each residence or each extension of a PBX is disclosed. Preferably, the location identification modules are powered by telephone line voltage. A location identification module is enabled when its associated telephone goes off-hook and an emergency code, e.g., 911 is dialed. Thereafter, in response to an inquiry from the emergency response center that receives the emergency call, the location identification module sends the location of the associated telephone to the emergency response center operator where the location is displayed on a dispatcher's console.

Abstract: A system and method for adjusting telephonic control signals transmitted from a central station to a remote station. The signals are automatically adjusted according to the response of the remote station. The signals are adjusted to control speakerphone operation at the remote station in such a way as to provide communication with minimum audible annoyance. The method is especially useful in a personal emergency response system in which the speakerphone is part of a subscriber station to achieve a greater voice range than a voice activated speakerphone system.

Abstract: A data transmission network uses a cellular network as a primary telecommunications link and a backup telecommunications link. The system continuously monitors the links and switches to the back up link if the cellular link is not operative. Examples of backup links include long-range radio and fiber optics. A software package is included in a computer at a monitoring station for effecting integrity checks of the links, and RF fault modules are also included. The RF fault module can be used in conjunction with a control panel having one line output or with a control panel having two separate line outputs.

Abstract: A security system for detecting and signalling the presence of abnormal security or hazardous conditions, such as unauthorized entry, glass breakage, fire, smoke, high water level, in individual units, such as a boat, a recreational vehicle, an automobile, which are located or stored in a given security area.. The security system comprises sensor units which, when actuated, transmit coded signals through the atmosphere which identifies each sensor unit and the individual unit on which it is located. A receiver on the individual unit recognizes only the coded signals from sensor units which are on the same individual unit as the receiver. A coded output signal is provided to a slave transmitter on the individual unit which identifies the particular sensor unit which was actuated. The slave transmitter provides a coded transmission signal to a local security station which identifies the particular sensor unit which was actuated and the individual unit where the actuated sensor unit resides.

Abstract: A personal emergency response system in which a hand held portable transmitter (12) activates a base unit (14) interfaced with the telephone network (16) to dial 9-1-1 and permit direct communications with the operator (18) at the public safety answering point even though the user (10) is unable to reach a telephone (36). The transmitter (12) activates the base unit (14) as well as optional remote units (48) located throughout the user's residence or place of business. The base unit (14) and remote units (48) include speaker-phone communication capabilities which permit two-way communications between the user (10) and the 9-1-1 system operator (18).

Abstract: A door phone controller has a door ajar feature for alerting a user that a door was left open. The door phone controller accommodates the door ajar feature in several different ways depending upon how it is configured to interface with the central office line. If the door phone controller is configured to interface with the central office line as an individual station, then when a door is left open, the controller alerts the user via auxiliary alert contacts specifically provided for activating a customer chime. When the door phone controller is configured as a ring-down station, the door phone controller alerts the user that the door was left ajar by dialing a pre-programmed telephone number and sending a door ajar tone. If the door phone controller is configured as an interface with a trunk port, then when the door is left open, the controller alerts the user by ringing the trunk line and also energizing the auxiliary alert contacts.

Abstract: An in-house paging system includes a call controller connected to an in-house switching unit for providing an interfacing process in response to a call request from an extension terminal. A plurality of transmitting units are connected to the call controller through a signal line and a power source line. A pager terminal is provided for notifying a maintenance staff of a call signal from a transmitting unit on receipt of the signal. The transmitting unit comprises a detecting unit for detecting whether or not an abnormal condition arises in a signal line or a power source line to a call controller and a signal/power-source line abnormal signal transmitting unit for transmitting abnormal condition information to the pager terminal when the detecting unit detects an abnormal condition in the signal line or the power source line. A battery as a backup power supply unit is used in case of power disconnection.

Abstract: The security for a person in a domicile, premise, or dwelling, is increased in the effectiveness thereof, by utilizing a remotely accessible security controlled audio link, which provides a hands free telephone answering system, that operates without the utilization of any conventional telephone located in the domicile. In a normal mode of this audio link, the telephone of a domicile is used in a conventional manner. However, when a telephone in the domicile is not answered within a time period of a designated number of rings, then the remotely accessible security controlled audio link operates to answer the incoming call by, in effect, functioning in an equivalent way, to lift up a conventional receiver, without the conventional receiver ever being raised.

Abstract: An intelligent alarm apparatus with a telephone network interface. The alarm apparatus includes an alarm sensor, which is directly connected at a high impedance level through an integrator and a detector to the alarm signal input of a programmable processor. The processor is in a power-saving standby mode until an alarm signal is received. Once an alarm signal is received at the processor, an output signal is transmitted to the designation programmed in the processor. A power supply section of the alarm apparatus is connected to a telephone line from which the alarm apparatus obtains its power feed.

Abstract: A data modem is provided with a boot ROM having a set of instructions for a programmable processor to perform its basic functions within the modem. Enhancements and firmware updates are downloaded over a telephone line through the modem's inherent communications abilities and stored in a battery backed RAM. This permits firmware updates and enhancements to be implemented remotely without need for replacement of ROM or opening of the modem housing.

Abstract: A cellular-based electronic house arrest monitoring (EHAM) system (10) electronically monitors parolees, or other personnel, required to remain at a house arrest location (12) or to report in at the house arrest location during certain hours. Monitoring occurs automatically under control of a host computer (50) at a central monitoring location remote from the house arrest location, regardless of whether conventional telephone service is available at the house arrest location. Tamper detect circuitry detects any attempt to tamper with the components of the system. The EHAM system includes an electronic tag (14) worn by the person being monitored that periodically transmits a unique identifying (ID) signal (16). The ID signal is transmitted at low power, and is receivable only over a limited range, e.g., 150 feet. A field monitoring device (FMD) (20) placed within the house arrest location receives the ID signal only if the tag is within range of the receiver, i.e.

Abstract: A cellular mobile radiotelephone (CMR 12) which detects and reports security breach conditions is disclosed. The CMR (12) includes a remotely programmable unit (RPU 48) in which alarm parameter data (1200) may be recorded from a remote programming (RP) host (22). An input (54) may be adapted to receive a vehicle alarm system (26) output. When the alarm system activates, a Mode 1 Alarm procedure (1700) is performed. If the alarm indication is deemed genuine, the CMR (12) automatically places a call to a security service (28). When a vehicle ignition signal (52) has just turned "on", a Mode 2 Alarm procedure (1800) is performed. A user is given a period of time, which is established remotely (1214), to enter a disarming code. If the disarming code is not entered in time, a genuine alarm event is assumed, and the CMR (12) places a call to the security service (28). In placing calls to the security service (28), numerous alarm parameters are established remotely.

Abstract: A security apparatus having two control and communications units adapted to monitor a system and to establish communications over a connected telephone line and to transmit an alarm upon the occurance of a predetermined event in the system. The first control and communications unit produces a characteristic signal when it is operational; and the second control and communications unit is adapted to monitor the characteristic signal produced by the first control and communications unit and to establish communications over the connected telephone line and transmit an alarm upon interruption of the characteristic signal. The characteristic signal is preferably a tone of predetermined frequency.

Abstract: A system and method for adjusting telephonic control signals transmitted from a central station to a remote station. The signals are automatically adjusted according to the response of the remote station. The signals are adjusted to control speakerphone operation at the remote station in such a way as to provide communication with minimum audible annoyance. The method is especially useful in a personal emergency response system in which the speakerphone is part of a subscriber station to achieve a greater voice range than a voice activated speakerphone system.

Abstract: A monitoring and control system has a programmable apparatus connected to equipment to be monitored.

Abstract: A data transmission network uses a cellular network as a primary telecommunications link and a landline as a backup telecommunications link. The system continuously monitors the links and switches to the back up link if the cellular link is not operative. A software package is included in the computer at a monitoring station for effecting integrity checks of the links, and RF fault modules are also included.