Abstract: An alarm system which incorporates a large number of ambient condition sensors makes a determination as to the existence of a predetermined alarm condition by detecting respective ambient conditions from each member of a group of sensors. The indicators from the plurality of sensors are each raised to a respective predetermined exponent and summed together. The resultant sum is compared to a predetermined threshold to determine whether or not the alarm condition is present. The detectors can be spaced apart from one another in a selected region and coupled to a central control unit by a bi-directional communications link. Running averages of sums can be formed to provide filtering or smoothing or trend analysis.

Abstract: Disclosed is a remote supervisory system in which slave supervisory apparatus (S-SV) for supervising network elements can be polled from a master supervisory apparatus (M-SV), and yet each S-SV is able to send an alarm signal to the M-SV at any appropriate time. In this system, a first transmission path connected to the M-SV is connected via a switch to a second transmission path leading from each S-SV. The switch is controlled in accordance with the presence of a signal on the first transmission path and also with the presence of a signal on the second transmission path.

Abstract: An apparatus for testing the operation of an irrigation system is disclosed. The apparatus pinpoints defects in the irrigation system controller by simulating control signals and processing the control signals through controller output chips. Visual indicators offer an indication of defects in output chips. The apparatus may be coupled to the controller and receives potential from the controller. The potential is converted to produce a signal for operating the tester. An oscillator/clocking section produces serial data input, strobe pulse, and clock pulse signals to simulate signals produced by the controller microprocessor. These signals operate the visual indicators and are simultaneously processed through the controller output chips. Defects low in the output chips prevent the operation of visual indicators. The absence of an operating visual indicator represents a defect in the output chips.

Abstract: An event detection system with centralized signal processing and dynamically adjustable detection threshold includes a number of remotely located event detection units coupled to a single centralized signal processing unit. Each event detection unit provides an event detection signal to the centralized signal processing unit. At least one signal processor in the centralized signal processing unit compares the value of the event detection signal with a dynamically adjustable threshold value, and provides a first detection signal when the event detection signal exceeds the value of the dynamically adjustable threshold. A threshold generator compares the event detection signal and a predetermined offset value, and adjusts the value of the dynamically adjustable threshold as the event detection signal exceeds the offset value. The signal processor then provides a second event detection signal when the event detection signal exceeds the adjusted threshold value.

Abstract: An intelligent alerting and locating communication system includes a centrally located scanner which communicates with a plurality of remotely located receivers to continuously monitor conditions through a plurality of detectors associated with each receiver, including smoke detectors and motion detectors, and through personal radio transmitters. Each detector detects an off-normal state in a monitored condition and makes an indication that is sensed by at least one receiver which stores the occurrence in memory. Each radio frequency transmitter emits a unique coded signal which is received by one or more receivers. If the coded signal is in a valid format, the coded signal is stored in memory. If the coded signal matches a unique code assigned to that receiver, a matched code signal is generated and also stored in memory.

Abstract: A brake monitoring and warning system is intended for use on a motor vehicle (110), and more particularly is intended for use on tractor-trailer combinations. The vehicle includes plural, powered brakes. Each brake includes a brake activation arm (18) and a mechanism (16) for shifting the brake activation arm between a brake-off position and a brake-applied position, such as an air-driven cylinder. The monitoring and warning system includes a sensor (26) which is connected to the brake-activation arm (18) and monitors the position of the brake-activation arm. The sensor generates and transmits a brake condition signal which is representative of a safety condition of the brake associated with a particular brake activation arm. A logic mechanism is connected to the sensors and receives and interprets the brake condition signal. Visual (160, 162) and auditory (164) warning devices are connected to the logic mechanisms for warning the vehicle operator of the safety condition of the brakes on the vehicle.

Abstract: A terminal of a disaster prevention monitor of the present invention detects the power-on of a terminal and sets flag information. When a polling call from a central monitor (receiver) is directed to a terminal after a power-on operation, the terminal transmits an information fetch request signal which requests the receiver enter an initialization routine for initialization of the terminal information. The receiver transmits an information request command signal to the terminal. The terminal transmits information to the receiver identifying the type of terminal which is responding. Depending on the type of terminal, the receiver may command test operations at the terminal and obtain the test results therefrom in order to generate and store proper initialization information about the terminal.

Abstract: A system for preventing unauthorized access to the programming and control features of a fire/security/control systems remote sensors. The exemplary embodiment of the present invention utilizes an association of transmitter identity/address with a central processor/control fire/security data base, which in turn is configured to securely program each transmitter with its location and function, or "personality". The various, individual sensors and central processor/control unit communicate individually via individual, repeatable pseudo randomization algorithms, producing a several bit result. The communicating central processor/control and each sensor must have a match on outgoing/incoming code before the transmitting sensor will accept the programming on its personality. The exemplary embodiment of the present invention also utilizes a randomization seed, which can altered occasionally, to further increase security.

Abstract: An anti-disaster system for receiving terminal data in response to the sequential calling of the terminals which is achieved by designating addresses from a receiver and for performing alarming or the like. Each of the terminals has an interrupt transmission section for transmitting a break signal which invalidates a terminal response signal on a timing when the terminal response signal to the receiver is transmitted when an abnormality is detected to notify generation of an interrupt.

Abstract: An intrusion detection system employing multiple bistatic microwave links and wireless means for remotely interrogating each link to provide alarm and status information at a central station. The central station includes a microprocessor for remotely adjusting the operating parameters of the microwave transmitters and receivers forming said links to increase the probability of intrusion detection and reduce the probability of false alarms.

Abstract: A communication system comprises a control station and a number of remote stations connected to the control station by a multi-conductor harness. The control station houses a computer and supplies the remote stations with electrical power, as well as communicating bidirectionally with the remote stations, via the harness. At each remote station, a sensor or other functional module is plugged into an interface. Communication circuitry receives data from and sends data to the control station. The remote station includes an identification device for storing a first code allocated to the remote station by the central computer which identifies the relative location of the remote station, as well as a second code generated at the remote station which identifies the function of the sensor or other functional module.

Abstract: A flashtube circuit includes a switch which in a first position regulates the storage over time of energy in a first energy storage device and in a second position allows the transfer of energy from the first energy storage device to a second energy storage device. A microcontroller receives the input voltage and then samples and digitizes it for input into a lookup table. The microcontroller repeatedly cycles the switch between flashes by controlling the time the switch is in its first position. The lookup table output provides the signal for determining the time the switch remains in its first position. The time interval from the last flash controls the time the switch is in its second position. The cycling of the switch is controlled accordingly such that the second energy storage device acquires the predetermined amount of energy for the flash just as the triggering circuit is initiated by the microcontroller.

Abstract: A multi-sensor security/fire alarm system comprises a master control unit which repeatedly interrogates, e.g., by a multiplexing scheme, the respective inputs and/or operating status of a plurality of remote sensor units (e.g., intrusion and fire sensors). In response to an alarm or other off-normal condition detected by any of the remote sensors, the master control notifies an alarm-monitoring service which either responds itself to the detected condition, or notifies the local police or fire department. To prevent one alarm-monitoring service from taking over, without authorization, the alarm-monitoring accounts of another service which may have expended considerable time and expense in installing the system, the master control unit is mated with its associated sensors by a unique code. According to a preferred embodiment, each sensor comprises an EEPROM which stores a unique portion (e.g.

Abstract: A security/fire alarm system includes a plurality of event-sensors, e.g. intrusion and smoke sensors, each being identifiable by a unique digital address defined by a multibit binary address code. A central control unit operates to repeatedly address the sensors to determine their respective alarm and/or operating status. To minimize the cycle time required to sequentially interrogate all sensors, the central control unit operates to address groups of sensors simultaneously, each of the groups consisting of a sub-plurality of all the sensors. In response to being addressed, each sensor in an addressed group of sensors transmits a different binary bit or digit of a multibit digital response code which is defined collectively by the transmitted bits. The logical state of each of such binary bits indicates the general status (i.e. normal/abnormal) of the event-sensing unit that transmitted the bit.

Abstract: Disclosed is an anti-disaster system in which terminals are called by the polling system and in which the response signals from the terminals are received and decoded by a receiver to issue an alarming. Each of the terminals has an interrupt transmission section for transmitting an interrupt signal at a predetermined time during the receiver's transmission of the calling signal when an abnormality is detected. The receiver has an interrupt detection section for monitoring the predetermined time during the transmission of the calling signal to detect an interrupt signal from the terminal, and a calling control means for sequentially performing terminal group calling when the interrupt detection output is obtained from said interrupt signal detection section to specify the terminal in which abnormality data is detected.

Abstract: A security system in which sensors are included in one or more groups which are stored in the system. Groups of sensors are selectably actuable by a user entering mode information into the system so that only the selected group(s) will provide indication of an alarm condition when a sensor indicates an alarm event has occurred.

Abstract: A communication system in which a controller is coupled over a communication path with two or more transponders, at least two of which transponders have different addresses, which controller and transponders communicate by periodically transmitting a broadcast message simultaneously to all transponders, transmitting an acknowledge message indicative of a new input received by at least one of the transponders, and individually polling all of the transponders using a polling technique which incorporates time periods to allow communication between the controller and a selected transponder, wherein the polling is only activated subsequent to the transmission of the acknowledge message. Periodic polls of all transponders in sequence provide supervision of the integrity of the system.

Abstract: A computer-based display apparatus is provided for a fire alarm system having sensors located at various positions in a building or area. The display apparatus includes a computer with associated memory and display, as well as a facility for obtaining one or more screen images of the layout of the building or area from graphical representations of the layout, such as drawings, photographs or CAD generated data. The screen images are stored in memory for display on the computer display. The display apparatus also comprises a software facility for superimposing the positions of the sensors on the displayed layouts.

Abstract: A method and apparatus multiplexing multiple alarm and head type values in a peripheral fire alarm device includes a head component for sensing the presence or absence of smoke or heat and a base component for communicating with the control panel. A communication interface between the base and head components with no more than three connectors for multiplexing the values between the head component and the base component. The control panel stores algorithms particular to each type of head which may be used to determine if an alarm condition exists. Using data received from the peripheral fire alarm device, the control determines which type of head component is currently installed at the base component and selects the correct algorithm.

Abstract: A security system provides for bidirectional communication between a controller and a plurality of addressable transponders. At least one transponder includes a sensor circuit for detecting motion, which motion is indicated by the transponder signalling back to the controller. During a walk test the controller sends a signal back to the transponder, completing the circuit for the visible output indicator so that subsequent motions during the walk test sequence will be immediately displayed at the transponder, without necessitating successive communication through the loop including the controller. In systems where the controller itself reports upwardly in a hierarchy of units, the walk test can confirm operability of the entire system, including other condition-indicating signals.

Abstract: An intrusion detection system employing multiple bistatic microwave links and wireless means for remotely interrogating each link to provide alarm and status information at a central station.

Abstract: A power supply control device is provided in a fire alarm system having terminals such as fire detectors and/or repeaters with comparators to detect abnormalities such as fire or an operating status of controlled apparatus, and is equipped with a reference voltage supply a source to supply reference voltage to the comparators, and a power supply control to allow the reference voltage to be supplied to the comparators only during the detecting time.

Abstract: A fluid status detection system includes a plurality of probes connected to a controller. The controller includes a microprocessor, a digital memory, relays, and progammed so that selected alarm and relay latching conditions may be stored, and alarms activated and relays latched according to the alarm and latching conditions. The microprocessor is programmed to provide an alarm acknowledgement signal upon the alarm being acknowledged. An operator may select one or more release conditions individually for each relay from a plurality of possible relay release conditions and store the conditions in the memory. The possible relay release conditions include: the condition that the probe signal indicates that the event that caused the alarm has cleared; the condition that the alarm acknowledgment signal has been provided; the condition that the probe signal indicates that the event that caused the alarm has cleared and the the alarm acknowledgment signal has been provided.

Abstract: A fire alarm system in which an analog type sensor (3) is connected to a transmission line (2) from a receiver (1) and in which one or more on-off type sensor (7) located in the same monitor area (14, 15, 16) as that in which the analog type sensor (3) is provided is connected to a signal line (6) led out from the analog type sensor (3). The analog type sensor (3) is provided with a fire detection circuit (12) for detecting a fire signal from the on-off type sensor (7) and a transmission control circuit (11) for transmitting its own analog detection data and fire detection data from the fire detection circuit (12) to the receiver (1).

Abstract: A smoke and fire detection system wherein a central controller transmits data to remote transponders on a voltage supply line by pulse code modulation (PCM) of the supply voltage, and the transponders communicate with the controller by pulse width modulated (PWM) current pulses over the voltage supply line. A transmitter in the controller supplies a nominal operating voltage to the transponders and transmits a data word comprising a plurality of data bits to the transponders over the line. The transmitter generates each data bit by switching the voltage supplied to the line from the nominal operating voltage to a first voltage corresponding to a first logical level or a second voltage corresponding to a second logical level. A decoder in each transponder derives the transmitted data word.

Abstract: A fire alarm system includes a receiver unit such as a fire control panel or a repeater having zone lines connected thereto, with various types of fire detectors being connected to the zone line. Supervising power is normally supplied to the zone lines. When the receiver unit receives a fire signal via a zone line from a fire detector, the receiver unit decides from what type of detector the fire signal was transmitted. Types of fire detectors include, for example, a type having as switching means only a mechanical contact for causing said zone line to be in a short-circuited condition, a type having as switching means a switching circuit with a self-holding function, or a type having a response lamp.

Abstract: Method and apparatus for programming sensors in a security system comprising a central monitor for generating a localized magnetic pulse signal, and one or more sensors each incorporating a magnetic switch for sensing the magnetic pulse signal generated by the central monitor and in response enabling programming of the sensor with data encoded within the magnetic pulse signal.

Abstract: A multizone intruder detection system comprises a supervisory circuit for verifying, while the system is disarmed, that each of a plurality of intrusion sensors is, indeed, functional. The supervisory circuit inhibits rearming of a disarmed system until it determines that each sensor has successfully operated within a relatively brief time interval just prior to the time an attempt is made to arm the system. A timing circuit, activated by a preliminary arm signal, operates to establish a time window (e.g. 10 minutes) within which the operability of each sensor must be verified (i.e. walk-tested) as a precondition to system arming. Preferably, the timing circuit is reset by each sensor alarm output, whereby the system user is given the full time window to walk-test each sensor. By virtue of the invention, sensor sabotage in a disarmed system can be mitigated.

Abstract: A multizone intruder detection system comprises a supervisory circuit for verifying, from normal traffic or activity in each of the zones of protection while the system is disarmed, that each of the intrusion sensors is, indeed, functional. In the event one or more sensors does not trip (i.e., sense activity) during the disarm period, the supervisory circuitry inhibits re-arming of the system until the non-tripped senso(s) is "walk-tested" to verify that it is still functional. According to the invention, a programmable timer enables re=arming of the system for a predetermined (preferably brief) time interval immediately following disarmig of the system. This feature offers the edvantage of allowing the user to re-enter the protected premises "after hours" for a brief period of time without having to walk-test all zones of protection before re-arming the system.

Abstract: A fire alarm system includes a receiver unit connected to a plurality of terminal unit groupings, each of the terminal unit groupings made up of a plurality of terminal units. The fire alarm system operates in one of a system polling mode, a point polling mode and a selecting mode. In the system polling mode, the receiver units polls all of the terminal units and provides a grouping response period in which each of the terminal unit groupings is permitted to respond to the receiver unit polling. If one of the terminal units of a particular grouping undergoes a status change, such a terminal unit transmits to the receiver unit a group response signal during the corresponding group response period. Then, the system enters the point polling mode, in which the terminal units of the terminal unit grouping corresponding to the group response period in which a group response signal was received are polled.

Abstract: A system for collecting alarms from a set of stations includes a central station (SC) connected in series with the stations over a loop link includes a message loop (BM), a clock signal loop (BH), and a state control loop (BCE). Each station includes an interface (5) connected to the various loops of the link. The message loop conveys messages transmitted by the central station and intended for at least one of the interfaces, replies from the interfaces, and messages transmitted by the interfaces and intended for the central station. The clock signal loop conveys a clock signal transmitted by the central station and the state control loop conveys a state control signal also transmitted by the central station, the signal taking a first value for an active operating mode of the interfaces and a second value for a standby operating mode of the interfaces. Changing over from the first value to the second also serves to reset the interfaces to zero.

Abstract: An annunciation system for a wireless weighing system. The weighing system includes control keys for selecting and displaying the weights from a plurality of remote weighing pads, each having a separate through the air communications channel. The weighing system further provides a mode for storing a zero value for each pad. In the preferred embodiment, the annuniciation system comprises a plurality of LED combinations where each combination is located proximately to a corresponding pad select key which indicates a particular communications channel. Each LED combination has a plurality of states including off, green, red and amber which indicates a condition of the corresponding communications channel. Additionally, each LED combination can indicate a condition of a corresponding communications channel by being off, on steady, or blinking.

Abstract: A security alarm system includes a transponder having a housing enclosing both a sensor and associated circuit means in a unitary package. The housing base includes barrel-shaped connectors, and a pc board carrying the communications components is carried by the housing cover. Flag-like connectors mate with the barrel-shaped connectors when the cover is attached to the base, and the connectors give both good mechanical indexing and retention, and effective electrical contact. Removal of the cover from the base breaks the electrical contact and thus breaks continuity back to the system controller, indicating someone has tampered with the system.

Abstract: A signal control system for transmission circuits which includes two ring counter type transmission circuits respectively formed of a plurality of transmitter-receivers located opposite to each other, a control circuit, and a couple of signal lines respectively formed of two alternate signal lines, a control signal line and a transmission line. The first pair formed of the first transmitter-receivers of the respective two transmission circuits are simultaneously operated, and subsequent pairs of the transmitter-receivers of the transmission circuits are synchronously operated in turn by a shift pulse. The system can transmit signals and control the transmission circuits without complicated circuits such as an address circuit and a verification circuit so that the construction is simplified and its power consumption is largely reduced.

Abstract: A system is provided for electronically monitoring a group of sensor switches employed at remote locations in security or alarm systems. To monitor the status of individual switches, a matrix of conductors is employed. The matrix has a predetermined number of send conductors by a predetermined number of return conductors. Switch circuits each having a diode connected in series with one of the sensor switches are connected at selected crosspoints of the matrix of conductors between respective send and return conductors. Line selection circuitry responsive to an input signal from a computer selectively permits the supply of a sourcing voltage potential to at least a selected one of the send and return conductors and the supply of a sinking voltage potential to at least a selected one of the remaining send and return conductors.

Abstract: Continuous status monitoring of a plurality of switches and smart sensors associated with the switches, wherein each sensor is connected to a separate single point in a single wire bus is a affected by a smart sensor multiplex arrangement employing an automatic wake-up circuit. The automatic wake-up circuit allows activation of any switch of a group of high priority switches to automatically take a microcontroller out of a wait mode and causes it to go into a POWER-ON mode. In the POWER-ON mode, power routes all circuits in the entire system and then a polling of all the switches and sensor modules is performed.

Abstract: An LED bar graph display is disclosed, which can simultaneously display signal strength and diagnostic information. When an input signal is received, the indicators are selectively operated to display a strength value of the input signal. When a diagnostic condition occurs, the indicators are selectively operated to display the diagnostic condition. Thus, the LED bar graph display performs the dual functions of displaying signal strength and diagnostic information.

Abstract: An arrangement for conserving the alarm-state power supplied to numbers of light emitting devices included in respective addressable terminal units of a fire alarm system or the like. The addressable terminal units are connected to a transmission line or loop; and a loop controller cyclically transmits address signals to the terminal units (polling routine); the controller functions, responsive to received data from those units, to generate an alarm-state display command signal for causing illumination of the light emitting devices of terminal units that are in alarm. In the case where a terminal unit comprises a master transponder to which a group of non-addressable conventional "slave" detectors is connected, the loop controller is programmed to disconnect such slave detector from the loop or line when more than one of them is in alarm. However, in the event of a large number of terminal units at scattered locations being in alarm, a tell-tale signal from each unit is highly desirable.

Abstract: An environmental monitoring system in which a controller is arranged to test the workability and reliability of a plurality of detector units on a cyclic basis. Each unit has an analog sensor and an analog to digital converter for converting the analog sensor voltage to a digital value in a range of 0 to N. Each unit responds to a test instruction to cause the sensor analog output to assume an alarm value. The sensor output is limited to a maximum value that under a no drift condition of the analog to digital converter, its corresponding digital signal value will be intermediate a tolerance range of values, the upper limit of such range being less than N. The controller includes a test routine program for both issuing the test instruction and for determining if the digital signal test value is within the tolerance range and issuing a trouble output indicative of the test value being outside the range.

Abstract: A fire alarm system in which a large number of terminal units, comprising detectors and interface circuits, at a variety of locations are coupled or connected in separate, independent loops of the system, each of the scattered terminal units being addressable from a central control panel. The arrangement is such that serial synchronous power transmission and data communication is effectuated over the individual loops of the system. The improvement resides in providing continuity-isolation testing for a Class A wiring scheme involved in the loops. By Class A operation is meant that there are two separate channels involved in each loop. A continuity test is sequentially performed on both channels of the loop such that discontinuities can be precisely located.

Abstract: A powered communications link between a central controller and a remote substation along a conductor that includes a movable or intermittent contact interacting therebetween includes a power supply located at the central controller for supplying electrical power over the conductor to the remote substation and an electrical power storage device at the remote substation for storing the power supplied over the conductor. Data and power are multiplexed over the conductor by the central controller which periodically stops the application of power to the conductors to permit a transmitter at the remote substation to send data to the central controller. A switch at the remote substation connects the power storage device to the conductor when power is being sent and disconnects it at all other times.

Abstract: A smoke and fire detection system wherein a central controller transmits data to remote transponders on a voltage supply line by pulse code modulation (PCM) of the supply voltage, and the transponders communicate with the controller by pulse width modulated (PWM) current pulses over the voltage supply line. A transmitter in the controller supplys a nominal operating voltage to the transponders and transmits a data word comprising a plurality of data bits to the transponders over the line. The transmitter generates each data bit by switching the voltage supplied to the line from the nominal operating voltage to a first voltage corresponding to a first logical level or a second voltage corresponding to a second logical level. A decoder in each transponder derives the transmitted data word.

Abstract: A control system has a central unit for applying DC operating current and control signals to a two line bus. The central unit applies a DC operating current to the bus, as well as signals that have first and second parts. A terminal connected to the bus detects first signal parts on the bus that are unique to that terminal, and, in response thereto, applies the second signal parts to its output terminals. A manual control unit is connected to receive operating current and signals from the output terminals. The manual control unit has a plurality of keys connected to load the bus, and is responsive to determined second signal parts for inhibiting such loading of the bus, thereby enabling the central unit to determine and address of the manual control unit.

Abstract: A time multiplexed integrated alarm contact for reporting detected alarm conditions to a system controller in a hardwired alarm system and wherein distinguishable binary frequencies are used for synchronizing/responding and for programming the contact. During programming, an identity code is written into an included shift register and non-volatile memory defining the system reporting interval and the contact's reporting interval within the system interval. Controller initiated synchronizing signals induce each contact's status transmission with or without resetting an alarm buffer and whereby redundant alarm reports may be obtained.

Abstract: An apparatus and method for reporting verification testing of a portable activator is provided for a personal emergency response system. In normal operation of the system, a signal transmitted by the portable activator activates a subscriber unit in a remote subscriber station to transmit an alarm message to a central station, or in some configurations to provide a local test or to cause other local or remote commands and/or control. The subscriber unit according to the present invention includes a latch assembly which is "set" upon receipt of any activating signal transmitted by the portable activator. The system also includes timing/logic circuitry, in the subscriber unit or alternately as part of the equipment of the central station, which automatically activates the subscriber unit upon expiration of a predetermined period of time to transmit a system test message to the central station.

Abstract: A transmission circuit is disposed in at least one of a control panel and a plurality of terminal devices of a fire protection/security system, wherein the control panel individually polls the terminal devices to read in terminal information from the terminal devices, to judge and/or display the information, or to control the terminal devices. The transmission circuit includes a signal sending device for sending a signal to a signal line, a memory device for storing a signal to be sent to the signal line, and a coincidence decision device for deciding a coincidence between the signal sent from the signal sending device and the signal stored in the memory device.

Abstract: An automatic testing method and apparatus for proximity switches toggles a proximity switch while storing the initial state of the proximity switch until the toggling is successfully completed. Both the proximity switch position and the validity of the information are provided as outputs.

Abstract: In a fire alarm system wherein a receiver polls terminal devices having CPU's, such as fire detectors, fire sensors and repeaters, and the receiver reads monitoring information called from the terminal device or transmits control information thereto; a fire alarm system constructed so that each of said terminal devices having a CPU brings said CPU included therein into a standby status when a polling address of said receiver and an intrinsic address of said terminal device are different.

Abstract: A transceiver unit for an electronic surveillance system is internally coded with an address-number for identification within the system and is adapted to receive input from sensors detecting alarm conditions. The unit is switchable from an idle condition wherein it transmits digital data relevant to its address-number and status but does not recognize input from a sensor, to a primed condition wherein it transmits digital data relevant to its address-number and status information indicating an alarm condition. The unit is able to receive digital data from other similar units sequentially and display information relevant to the identity and status thereof. In a security system a plurality of such units communicate with each other and in turn transmit the digital data to all the other units of the system simultaneously, either by hard wiring thereto, radio link or other transmission medium. An alarm condition detected by one unit is recognized at all other units of the system.

Abstract: A self-powered sensor for a closed-loop security system includes a self-powered sensor network which provides a switch-actuating signal upon the detection of a physical condition. An electronic switch, which is in a normally closed position, is connected between the positive and negative poles of a closed-loop security system and opens the loop upon receipt of the switch-actuating signal thereby triggering an alarm. The self-powered sensor network may include a voltage doubler for converting the AC output of a transducer to a DC voltage of an amplitude sufficient to open the switch. When the switch is opened, voltage from the closed-loop security system becomes available to power a visible or audible alarm identifying the sensor that opened the loop.