Abstract: A computerized-system for anomaly detection of Point-to-Point avionic communication messages via a message-bus between an entity to one or more aircraft-systems in an aircraft during phases of flight, is provided herein. The computerized-system may include a bus-message queue to store bus-avionic-communication-messages transmitted via one or more input buses; an anomaly queue to store anomaly bus-messages; a memory to store the bus-message queue and the anomaly queue; a C-BIT mechanism to operate one or more preconfigured test routines; and one or more processors to operate a rule engine based on a preconfigured ruleset to detect one or more anomalies of bus-avionic-communication-messages for each bus-message in the bus-message queue; The rule engine may be configured to store each bus-message that is detected as an anomaly in the anomaly queue and to send one or more alerts to be presented via one or more external devices for each bus-message in the anomaly queue.

Abstract: A hybrid cable applicable in oil wells is disclosed, comprising a FIMT, a conductor layer formed by continuous laser welding and cylindrically covered the outer surface of the FIMT, the outer cylindrical surface of the conductor layer being covered with a high temperature resistant insulating layer by a continuous extrusion method or by wrapped helically with insulating tapes around the outer surface of the conductor layer and the external steel tube cylindrically covered the outer surface of the insulating layer. The conductor layer is coaxial with the FIMT, the inner space of the hybrid cable to accommodating excess length of the optical fiber for thermal expansions or the tensile stress of the optical cable. The thickness of the insulating layer cylindrically covered the outer surface of the conductor layer can be increased, thereby improving the insulating property. A method of manufacturing such hybrid cable is disclosed.

Abstract: Method and apparatus for nonlinear signal processing include mitigation of outlier noise in the process of analog-to-digital conversion and adaptive real-time signal conditioning, processing, analysis, quantification, comparison, and control. Methods, processes and apparatus for real-time measuring and analysis of variables include statistical analysis and generic measurement systems and processes which are not specially adapted for any specific variables, or to one particular environment. Methods and corresponding apparatus for mitigation of electromagnetic interference, for improving properties of electronic devices, and for improving and/or enabling coexistence of a plurality of electronic devices include post-processing analysis of measured variables and post-processing statistical analysis.

Abstract: An apparatus for determining and/or monitoring at least one process variable of a medium in a container which comprises a mechanically oscillatable structure, which has at least one oscillation characteristic dependent on the process variable, an electromechanical transducer having at least one piezoelectric element, which excites the structure, by means of an excitation signal supplied to the transducer, to execute mechanical oscillations, and which converts the resulting oscillations of the structure into a received signal, which corresponds to a superpositioning of the excitation signal and a wanted signal representing the oscillation.

Abstract: A traffic management system includes a data processing unit which communicates with a road leading unit and a vehicle management unit. The road leading unit comprises a plurality of grooves and isolation railings, the grooves are formed on a road, and the isolation railings are received in the grooves and can be opened to divide the road. The data processing unit can receive vehicle identification information and driving direction information from the vehicle management unit. The data processing unit comprises a data analysis module and a control module. The data analysis module is operable to estimate road condition information and count a total traffic demand index for each road according to the vehicle identification information and the driving direction information. The control module is operable to control the isolation railings to open or retract according to the total traffic demand index.

Abstract: To test whether a trailer is coupled to a tractor when the tractor ignition switch is off, a test switch in the trailer connects a high-impedance power source in a trailer to a line carrying energy from the tractor ignition switch to the trailer's electrical load, and measures the voltage at the line. A high voltage indicates a connection only to the electrical load in the trailer and thus a decouple. A low voltage indicates a measurement of the electrical loads in both trailer and tractor and hence a coupling.

Abstract: An alarm trend summary display system and method can utilize an alarm trend list that works together with an alarm summary list. A set of rows in the alarm trend list can be organized in a top-to-bottom manner. A set of alarm indicators within each row in the alarm trend list can be arranged in a right-to-left horizontal arrangement. The set of alarm indicators can be aligned with most recent alarms appearing on a right side of the alarm trend list. The specific alarm indicators can be selected in the alarm trend list, so that a corresponding item can be highlighted in the alarm summary list, if the alarms are active. Hence, the system and method can allow an operator to see when alarms occur, their sequence, relations and priority, which aid the operators cope with inevitable alarm floods.

Abstract: A lightning protection circuit for electric fence energizers used with electric fencing systems is provided. The circuit includes a protective combination having at least two electrical components connected in series. The protective combination allows induced voltage from lightning strikes to be effectively spread across a first of the electrical components and a switch of the fence energizer, so as to limit peak levels of current drawn to a second of the electrical components.

Abstract: To test whether a trailer is coupled to a tractor when the tractor ignition switch is off, a test switch in the trailer connects a high-impedance power source in a trailer to a line carrying energy from the tractor ignition switch to the trailer's electrical load, and measures the voltage at the line. A high voltage indicates a connection only to the electrical load in the trailer and thus a decouple. A low voltage indicates a measurement of the electrical loads in both trailer and tractor and hence a coupling.

Abstract: A method and system for assessing or otherwise determining defective operation of an electronic control unit (ECU). The ECU may be a vehicle or non-vehicle ECU having any number of modules configured to provide and/or support any number of operations. The defective ECU operations may be determined as a function of a voltage drop across a shunt included on the ECU.

Abstract: A method for monitoring a control circuit of an actuating device with at least one actuator including an actuated part and an electric member controlling movement of the actuated part, the control circuit including a bridge, the controlling electric member being connected in the bridge. The method includes: powering the bridge, producing at least one measurement signal representing the position of the actuated part, and selectively interrupting conduction in at least one branch of the bridge in accordance with the measurement signal to maintain the measurement signal substantially in an operating zone defined between a low threshold and a high threshold during a phase activating the controlling electric member. Conduction is interrupted in at least one branch to place the controlling electrical member in short-circuit via two branches of the bridge when the measurement signal reaches at least one specific threshold above the low threshold.

Abstract: A POE (power over Ethernet)-prioritized active splitter is disclosed for a prioritized network having different priorities such as a network security system that uses an intelligent POE power supply with a prioritized back-up response, allowing a lower cost UPS (uninterruptible power supply) system to be used, and also providing a longer back-up time period by the UPS system for more critical components of the security system. A simple embodiment operates with only two priority levels, a high priority level for more critical components of the, such as the cable modem, the system router, fire alarm devices, local warning devices and the alarm communicator, while less critical components are supplied with electrical power at the low priority level. In the event of a power outage or disconnection, the critical high priority components remain connected to the Ethernet network to be supplied with electrical power by the UPS system and also to communicate over the twisted wire pairs of the Ethernet network.

Abstract: A gear indicator provides a display to a motorcycle driver of which gear the motorcycle is currently operating in. The gear indicator is used with a gear position switch providing ground signal indication to a motorcycle CPU at a connection with a plurality of leads which reflect the gear a motorcycle is operating in, no indication indicating that the motorcycle is in first gear. The gear indicator bridges the gear position switch to the motorcycle CPU receiving this ground information through a bridge and a similar number of leads communicate with the gear indicator processor from this bridge. The processor of the gear indicator processes the information received to drive a display to reflect the gear to the operator.

Abstract: An event detection system has a control element coupled to a plurality of detectors, such as smoke detectors. The control element can be implemented with a programmed processor. The detectors can include a base which removably receives a separable detector housing and electronics. Group boundaries can be specified by incorporating boundary defining electrical elements, such as switches or resistors, into either a respective detector base or into the detector itself. The control element can include instructions for carrying out an automatic addressing process with respect to the detectors. Topology information obtained during the automatic addressing process in combination with the location of the boundary defining elements specifies one or more groups for the control element. In an alternate embodiment, groups can be defined based exclusively on the topology information. In this embodiment, boundary defining electrical elements are not needed.

Abstract: A theft-deterrent outdoor lighting fixture having an auger that is connected to the lowermost end of the lighting fixture by means of a one-way clutch mechanism. The one-way clutch mechanist engages or locks the auger relative to the fixture when turned in the same direction of the thread of the auger but free-wheels in the reverse direction to preclude removal of fixture. In another embodiment, the theft-deterrent outdoor lighting includes an electronic design that detects movement representative of theft and sounds an alarm to draw attention to the theft while in progress. In still another embodiment, the theft-deterrent outdoor lighting includes a wiring harness that is destructively severed should the lighting fixture be pulled from the ground, thereby rendering the lighting inoperable in the case of theft.

Abstract: The device for compensating a weak cooling/overcooling for a cooling chamber of a refrigerator has a plurality of resistances connected in series between the power and ground and a plurality of switches connected in parallel to the plurality of resistances. A microprocessor receives a voltage divided according to an open/close state of the plurality of switches through a single input terminal. The device performs a weak cooling/overcooling compensation operation.

Abstract: An ambient condition detector includes at least a sensor for a first ambient condition and a second, sensor which is responsive to a second ambient condition not necessarily correlated to the first condition. Control circuitry, coupled to both sensors, processes an output from the first sensor to reduce transients and/or noise therein which are not correlated to the first ambient condition. Processing characteristics are altered in response to an output from the second sensor. The processing can take place at the detector or, in part, at the detector and, in part, at a displaced, common control element. The output from the first sensor can also be used to modify the processing of the output of the second sensor.

Abstract: An in-building telephone distribution system has a multi-conductor telephone distribution cable, starting at the point where the telephone utility lines enter the building and extending from there to each location at which a telephone outlet is wanted, at which a smoke alarm is wanted, and/or at which one of numerous other devices (e.g., door chime) might be wanted. At a suitable point along the cable, a first pair of the cable's conductors is connected with the power output terminals of a Class-2 (or Class-2-equivalent) DC power supply, whose power input terminals are connected with an ordinary electric utility power line. Thus, at any point along the cable, the first pair of conductors may be accessed and used as a Class-2 DC power source. A second pair of the cable's distribution conductors is used for distribution of the telephone signals.

Abstract: A voltage indicator using a serial or sequential comparison voltage measurement technique. Reference voltages generated by a voltage divider are applied to inputs of a multiplexer which is driven by a counter to select one reference voltage at a time in sequence to be presented via an output terminal to one input of a voltage comparator. An input signal to be measured is applied the other input of the comparator. When the input signal matches or exceeds the reference voltage at the output terminal of the multiplexer, the comparator switches, providing an enable signal to a one-of-N decoder. The one-of-N decoder is also driven by the counter, so that outputs of the decoder and corresponding inputs of the multiplexer are addressed simultaneously. The outputs of the one-of-N decoder are connected to LEDs which indicate the voltage level or magnitude.

Abstract: The invention provides a system for detecting the presence of an electrically conductive object, the system comprising a first and a second contact (C1 and C2) intended to be short-circuited by said object, and further comprising a control device for the electric potentials of the contacts. In accordance with the invention the control device comprises means for applying a given potential (Vref), referred to as the reference potential, to the second contact (C2) at a high impedance (Z) with respect to the resistance generated by the contact with the conductive object to be detected, and for supplying a signal (CP) indicating that the potential of the second contact (C2) is near the reference potential (Vref).

Abstract: When one of the failure detecting devices disposed at some spots in an electronic appliance detects failure of the electronic appliance, the failure detecting device detecting the failure generates a certain voltage. From the voltage, a certain specific voltage of good stability is generated as a first information indicating the occurrence of a failure in electronic appliance, and a second information is generated indicating place of failure. A means is provided for generating voltage, or data, which contains the elements of both first and second informations. Based on the voltage, or data, generated from the means, a place of failure is specified and displayed.

Abstract: A warning or alarm sensor supervision circuit employs varying voltage levels which may vary at random intervals and to random levels.

Abstract: There is disclosed a tubular protective sheath for containing a power transmission conduit, the sheath comprising: first and second flexible elements each helically arranged to form respective inner and outer tubular members. The first element is in the form of a first electrically insulating film having respective first and second layers of electrically conductive low melt material adherent to its opposite surfaces. The second element is in the form of a second electrically insulating film having a third layer of electrically conductive low melt material adherent to one surface.

Abstract: An arrangement monitors a consumer in combination with an internal combustion engine or motor vehicle especially for monitoring an electric drive which is driven by an output stage in the form of a bridge circuit. Potentials are compared in the area of the consumer or of the output stage to pregiven threshold values derived from the normal operation. From this comparison, an alarm signal is generated in a time-delayed manner with the time delay being dependent upon the magnitude of the drive signal.

Abstract: A fire alarm system employs a neural network for obtaining one or more types of fire related information values. A plurality of detection information values are time-serially collected from plural fire phenomenon detectors. The detection information values are signal processed such that a weighting coefficient is assigned thereto in accordance with a relative significance of the detection information value to the desired fire related information value. The various weighting coefficients are stored in advance in a memory. The weighting coefficients stored are established so that the fire related information value for a particular set of detection information values approximates a desired fire related information value.

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: In a fire alarm system including a plurality of addressable detectors connected to a main circuit extended from a central receiving unit, any alarming detector is discriminated and indicated in accordance with its address on the receiving unit side. In this system, one of the addressable detectors is assigned as a group master detector to each of areas under surveillance and the other detectors within the same area under surveillance have no addressing function. The unaddressable detectors are dependently connected to the group addressable detector within the same area under surveillance.

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 security system comprising a signal-carrying member and a detector for detecting a change in the resistance of the conductive path surrounding a core of the signal-carrying member. The conductive path comprises inner and outer layers of semi-conductive tape separated by an insulating layer but interconnected at one end. The semi-conductive tape of at least the outer layer is made of fibrous material such as carbon-leaded PTFE such that when a sharp object pierces the outer layer and the insulating layer, semi-conductive fibers are dragged from the outer layer into contact with the inner layer and form a conductive bridge between the layers.

Abstract: An individual source identification of several signal providers or pick-ups with closable contacts disposed in a twin-wire signal line, in particular for fire detectors in fire alarm systems. The signal pick-up system allows to distinguish actuation of individual sensors separately and apart from a short circuit formation. The fire alarm system also allows connection to automatic sprinkler devices. The fire sensor system is easy to install in that the individual settings of the individual detectors at a construction site are minimized.

Abstract: An environmental abnormality alarm apparatus includes a sensor for detecting a fire, gas leakage, a burglar, or the like in a monitoring area, and a signal processor for receiving an output from the sensor and evaluating the output for an alarm determination reference and generating an alarm. A detecting unit is provided in the monitoring area of the sensor to detect a change in environmental condition resulting from objects or conditions other than those to be detected by the sensor, and an alarm determination reference is changed in accordance with an output state of the detecting unit during signal processing.

Abstract: A device for generating an alarm signal in the event of an environmental abnormality has multiple sensors, with a multiplier associated with each sensor, an adder, and a comparator. The sensors are disposed in respective sensing volumes, which may be different. The sensors detect a level of smoke, heat, gas or other environmental abnormality within each sensing volume, and convert the level into an electrical analog signal. The associated multiplier multiplies a coefficient proportional to the sensing volume for the associated sensor with the analog signals from the sensor. The adder adds the outputs of the multipliers. The comparator generates an alarm signal at an output thereof when the output of the adder exceeds a predetermined value.

Abstract: A single-wire loop alarm system in which the status of each alarm switch can be determined and which is relatively immune to the effects of noise. False alarms are avoided by incorporating an integrator in the loop potential test circuit; during polling, however, the integrator is switched out. Low-frequency noise is discriminated against by verifying the existence of an alarm condition; the loop current is doubled and, if the alarm condition is being caused by an impedance-introducing open alarm switch, the loop voltage change should double. Polling is made more reliable by relying on a "window" test, rather than a simple threshold test.

Abstract: A device for generating an alarm signal in the event of an abnormality in the environment of a detector includes a pair of signal/power supply lines, a number of detectors for detecting an abnormality, e.g., fire, gas leakage, or burglary, and an alarm receiver including a signal processing circuit for receiving a signal from a detector indicating the presence of an abnormality. The signal process circuit includes a signal storage circuit, and a converting circuit for changing one or a combination of at least two of a polarity, voltage, current, or impedance of a power source if the abnormality persists for a predetermined time. The change in the power source parameter is supplied via the supply lines to a signal holding circuit in the vicinity of the detector. The signal holding circuit is responsive to the changed parameter and changes state, thus providing an indication at the detector that the abnormality has persisted for the predetermined time.

Abstract: Apparatus for connecting in series a plurality of communication line pairs, typically direct connected security loops used by alarm companies for monitoring customer's facilities. A bridge with pairs of bridge terminals and switches for connecting bridge terminal pairs to communication line pairs or to terminating lines. Local and remote control for the switches and control apparatus which permits service personnel to selectively terminate a bridge terminal pair with a direct or zero resistance connection line and leave a subscriber's communication line open, for maintaining service for other communication lines connected to the bridge while performing maintenance on the disconnected line. The apparatus is suitable for bridges with various numbers of terminals, such as six way, eight way and twelve way.

Abstract: Separate signal input circuits respond to intruder disturbances of a capacitive wire sensing grid to generate signal outputs processed to reject signals caused by environmental phenomena with a high degree of statistical probability, by comparison of individual signal outputs with an averaged signal output from all of the signal input circuits.

Abstract: A signal transmitting junction unit for a hazard alarm system includes a signal transmission control unit, a zone line circuit connected to an electric source and having at least one hazard sensor connected thereto and an analog digital convertor; and the zone line circuit outputs the source voltage when a sensor connected to the zone line detects a hazard, outputs a voltage between the source voltage and the zero voltage when the sensor is under the normal monitoring standby condition, and outputs no voltage when the sensor is out of order upon calling from the central control unit and the voltage is digitized by the analog-digital converter and sent back to the central control unit through the transmission control unit.

Abstract: An intruder alarm system includes a number of sensors each of which comprises first and second series-connected resistances and a sensor switch connected in parallel with the first resistance. The first resistances of each sensor are different in value from one another, but their values are related in a known manner. The sensors are connected in series with one another by a connecting cable and to a constant current source. The voltage developed across the series-connected sensors is applied to a circuit arrangement operable to offset the effect of the total resistance of the second resistances of each sensor and of the connecting cable. An analogue-to-digital converter is responsive to the output of the circuit arrangement to deliver a digital output to an indicator which indicates the actuation of any sensor.

Abstract: A self-diagnostic ultrasonic motion detection system includes an ultrasonic transceiver operative in a transmit mode and in a receive mode. In normal operation, the ultrasonic transceiver in its transmit mode has a characteristic electrical impedance. Potential electro-mechanical, electrical, acoustical, and other sources of false and failure of alarm situations manifest as changes in the electrical impedance of the transceiver in its transmit mode. The electrical impedance is monitored, changes from the nominal are detected, and a suitable self-diagnostic alarm signal is produced in response thereto.

Abstract: An alarm terminal device has a lower limit voltage generator for generating as a lower limit voltage an analog signal which is produced from a temperature sensor and which is lower than a first predetermined value, and an upper limit voltage generator for generating as an upper limit voltage an analog signal which is produced from the temperature sensor and which is higher than a second predetermined value. At least one additional sensor is provided for generating an analog data signal having a voltage higher than the upper limit voltage or lower than the lower limit voltage so as to indicate any information other than that contained in the analog signal from the temperature sensor. A disconnection or a short circuit of a platinum resistor of the temperature sensor can thus be represented by the analog data signal to be quantized by an analog-to-digital converter employed in the sensor.

Abstract: A monitoring system for a protection loop that has a plurality of switches in series utilizes modules with inexpensive diodes and resistors, and is conveniently and easily added to existing burglar alarm circuits and loops. A monitoring module that includes a diode and a paralleled resistor is connected across each switch. First and second interrogating signals are alternately applied to the protection loop. First comparator circuit means provides an output in response to each first interrogating signal when one of the monitored switches in the protection loop is open as indicated by the response of the module resistors; and second comparator circuit means provides an output in response to each second interrogating signal when more than one of the monitored switches in the protection loop is open as indicated by the response of the module diodes.

Abstract: The integrity of a two-conductor transmission line, over which d-c energizing voltage is supplied to a series of shunt-connected detectors (such as fire and/or smoke detectors) and which line is terminated by an end-of-line capacitor, is monitored and repetitively tested by periodically and momentarily interrupting the application of the d-c energizing voltage to the transmission line or conductor pair, while at the same time connecting a resistive load across the line's input end to provide a discharge path for the capacitor. If the integrity is normal, meaning that the line is continuous and not open, and has no excessively high series resistance or excessively low shunt resistance, and also meaning that the capacitor is functioning normally and is not deteriorated, the capacitor will discharge very little during each test and will maintain a relatively high voltage across the resistive load.

Abstract: A security system including a plurality of sensor loops, each having a plurality of detectors and associated detector identification devices which upon actuation produce analog detector signals of different amplitude for each detector in such loop to identify the actuated detector. The sensor loops each have a common loop output which is connected to a different one of a plurality of input terminals of an analog to digital converter and multiplexer circuit which includes a multiplexer switching circuit for selectively switching between such inputs and which converts the selected analog detector signal to a digital detector output signal. The outputs of the analog to digital converter are connected to a digital data processor circuit, such as a microprocessor computer, for processing the digital detector signals to determine which detector produced such signals and to generate a corresponding output signal that may operate an alarm means such as a bell or indicator light.

Abstract: A microcomputer controlled circuit arrangement for sensing fire and burglar alarms in the presence of undesired fault conditions, such as opens or shorts, on monitored communication lines. The arrangement includes transistor-resistor sensing circuitry which is shared by a plurality of monitored communication lines, each of which comprises a first pair of conductors connected to a first contact of an alarm sensor and a second pair of conductors connected to a second alarm sensor contact. The sensing circuitry is connected through a multiplexer to each one of the lines one at a time under control of the microcomputer to detect any fault thereon and any alarm provided by the sensor contacts. The sensing circuitry is responsive to impedance conditions on the four conductors furnishing a plurality of output voltages which are examined by comparators that, in turn, generate combinational logic voltages signifying the alarm-fault state of a monitored line.

Abstract: A single zone system which may use a single cable pair for both detectors of nonstandard conditions and audio/visual alarms. The audio/visual alarms are polarity responsive and in response to an alarm detection, comprising an increase in line current, the polarity is reversed and the line current supervision circuit disconnected. Some detectors or signaling devices may be polarity sensitive so that they present a high impedance under normal and reverse polarity conditions, and a lower impedance on abnormal conditions and prior to polarity reversal. Other detectors may be polarity insensitive and include a relay which may be activated from line potential subsequent to detection of an abnormal condition. The relay may be used to operate door closers or to initiate other appropriate action.

Abstract: An alarm detection, indication and supervision circuit with reduced power drain during failure of commerical power supply whereby standby batteries may maintain detection capability for an extended period. Separate detection and alarm indication loops are provided each with an end-of-line resistor which is removed from the circuit in response to a commercial power failure. A nearly unlimited number of detectors may be used on the detection circuit and each may have an auxiliary relay for control of local apparatus to permit local control, under changing ambient conditions. In response to an alarm signal, the potential on both loops is switched from a limited current supply to a hard supply and the polarity is reversed.

Abstract: A tire pressure monitor which includes a signal generating section and a signal processing section. The signal generating section has a transducer which produces a first signal which is dependent on the tire pressure, and a transistor the collector current of which is controlled by the first signal. The signal generating section is supplied with power from a battery source and the current so supplied includes the collector current and is therefore dependent on the tire pressure. The signal processing section includes a monitor which monitors the supply current to the signal generating section and a display for providing an indication of the tire pressure.

Abstract: In a central station alarm system the alarm sensors associated with a particular subscriber's premises are monitored by a local control unit associated with those premises and controllable by the subscriber. The local control unit automatically reminds the subscriber when he is supposed to close the premises and turn on the system. The local control unit allows the subscriber to change his expected closing time. The local control unit may also perform various other functions such as automatically cutting off power to low priority alarm sensors during a prolonged power failure, automatically cancelling any audible alarm indication silence commands when there are no alarms to silence, and automatically forming a bridge connection between the remote ends of two communication circuits when there is a break in either circuit.

Abstract: A fire extinguishing apparatus and an actuating system. The actuating system includes a plurality of actuators connected in parallel and a source of electrical signal for said actuators. Each actuator is connected in parallel with a device whose resistance decreases with increasing current through the device.

Abstract: A security installation has four, for example, normally-closed sensor switches which open in the presence of an intruder. Each switch is in series with a respective resistor and these series combinations are connected in parallel across a pair of bus lines which connect to a central monitoring point. There, normally open test switches are connected across the bus lines in series with respective resistors which have values corresponding to the resistors of the sensor switches. Constant current is applied to the bus lines, and a voltage monitor senses the rise in voltage when one of the sensors opens, and this initiates a scanning unit which closes the test switches in sequence. When the test switch corresponding to the opened sensor is closed, the line voltage reverts to the predetermined value, and the closed test switch identifies the operated sensor.