Abstract: There is disclosed an intrusion detection system employing vibration sensors which are arranged in a series loop consisting of first and second wires and which loop is terminated by a terminating impedance. Coupled to the wires is a processing circuit which supplies a square wave biasing waveform for the loop and a DC voltage determined by the terminating impedance. By detecting the magnitude of the DC level, the processor can determine if the loop has been opened or shorted or if any one of the sensors in the loop has been activated due to an intrusion. Thus the system described employs two wires for supplying both power and sensing of output signals from the loop being monitored.

Abstract: A fire detector which outputs a change in physical phenomena caused by fire, such as a change in smoke density, in the form of analog voltage signal, by, for example, a photoelectric type sensor, an ionization type sensor, a thermal sensor, a gas sensor or the like, converts the output voltage into a pulse width corresponding to the voltage level by a voltage-pulse width converting circuit, counts quick clock pulses over the pulse width by a pulse counter, and transmits the count output from the pulse counter, in the form of digital signal, to a central signal station.

Abstract: A remote sensing and indicating system for monitoring and displaying at a central operating location the state or position of a remotely located multiple state element. The multiple state element may be a subsea valve which may be either in an open state or a closed state. The system electronically scans valve position switches, stores data indicating the position and drives lamps to display valve position. Switches at the remotely located valve are selectively closed in response to the state of the valve. The switches are connected to the central location by only two leads.

Abstract: In a microprocessor controlled fire alarm system, a chain of continuous pulses is generated by the microprocessor. The chain of continuous pulses is monitored, and if there is an interruption in the chain of continuous pulses a signal is generated to automatically reset the microprocessor.

Abstract: A contactless motion detector responsive to the approach of a ferromagnetic element, including an oscillator with a sensing coil, has an output lead connected to one input of a first Exclusive-OR gate having another input connected to a square-wave generator whose pulses appear in the output of that gate with or without phase inversion depending on the output voltage of the motion detector. These pulses are fed, via an amplifier, to one input of a second Exclusive-OR gate whose other input receives the output pulses of the square-wave generator directly but with a delay compensating a lag introduced by the first gate and the amplifier. In the absence of a malfunction, the inputs of the second gate are energized either cophasally or antiphasally to produce either a low or a high output voltage of substantially constant magnitude fed to a load; in the event of a malfunction interrupting the pulse transmission to either input of this second gate, its output becomes a pulsating voltage.

Abstract: In a fire detector that includes a sensor for producing an output voltage corresponding to smoke concentration, temperature, etc., there is provided a charge-and-discharge circuit to be reset by the turning ON of a switching circuit which is made ON at a fixed voltage. The output of the charge-and-discharge circuit and the output of a sensor are applied to the switching circuit to vary the ON period of the switching circuit corresponding to the output voltage of the sensor. Any irregularity in the sensor can be monitored by changes in the ON period.

Abstract: A contactless motion detector, specifically an oscillator whose signal amplitude is attenuated or enhanced by the approach of a monitored metallic element, is periodically switched for brief periods into its alternate state by a train of short test pulses giving rise to corresponding checking pulses that are superimposed upon the integrated output voltage of the oscillator whereby that voltage is intermittently increased when at low level and/or intermittently reduced when at high level. These checking pulses, whether of the voltage-increasing or the voltage-reducing kind, are integrated to provide an enabling signal allowing a controlled load to be energized or de-energized according to the mean value of the output voltage; an absence of the enabling signal indicates a malfunction.

Abstract: A selectively testable fire detector comprises a fire detecting circuit supplied with a first voltage and which detects smoke and/or temperature, a self-holding circuit which is actuated by the output signal of the fire detecting circuit, a counter which counts pulses superimposed on the first voltage and outputs a signal when the counted number reaches a predetermined number assigned thereto, a latch circuit which latches the output signal of the counter and transmits to the fire detecting circuit a signal which actuates the fire detecting circuit, and a reset signal generating circuit which resets the counter and latch circuits by a second voltage which is higher than the first voltage.

Abstract: A central smoke detection system for a building having multiple rooms utilizes low cost commercial smoke detectors in each room. Each detector includes a steady high current alarm mode, a low current idle mode and a high pulse current test mode. A central power source supplies power to the detectors via one common lead and a separate power lead to each detector. A resistor in each power lead at the central location provides for monitoring of the mode of each smoke detector. A central monitor operates a visual smoke alarm responsive to the steady high current mode which indicates the room in which a detector is in the alarm mode and a visual fault alarm responsive to the absence of the high test pulse current indicating the room in which a detector is inoperative. A common central smoke and fault alarm, both audible and visual is also provided.

Abstract: Zone indication is provided for a facility monitoring and control system by providing the system's sensors and control unit with counters which are simultaneously incremented with clock pulses delivered to the sensors via the multi-wire interconnect cable from the system's control unit. Each sensor output circuit has enabling circuitry connected, as with jumper pins, to a counter output corresponding to a predetermined number or count, and this number or count identifies the sensor. In one embodiment, each sensor output is enabled only during the occurrence of the corresponding count or number from its counter as the counters are incremented through their cycle. When the sensors are used to sense alarm conditions, the sensor sending an alarm signal is identified when an alarm condition signal exists simultaneously with a particular count from the counter at the control unit, with the particular count indicating which sensor is sending the alarm signal.

Abstract: Burglar-proof barrier providing protection against intrusions, comprising means for the transmission of signals modulated and coded by pulses in a predetermined code, means for the reception of the modulated and coded signals transmitted and means for recognizing the predetermined code in the signals received, said recognition means supplying at an output a characteristic signal whenever the code is recognized, an alarm circuit whose input is connected to the output of the code recognition means and which supplies an alarm signal when the characteristic signal is absent, the code recognition means being constituted by a system of detecting pulses by coincidences and the modulated coded signals forming repeat pulse trains, wherein the system for the detection of pulses by coincidences comprises means for delaying, as from the first pulse in each train, all the pulses preceding the final pulse in the train in such a way as to bring them into coincidence with the latter, and a logic gate circuit for controlling

Abstract: The detection of events such as illegal entry detection, or the occurrence of predetermined hazards are detectable by a system including a circuit loop 2 which incorporates event actuatable switches 1, 35, 37, 38. Each switch has associated therewith means (9, 36, 37a, 39) for both maintaining electrical continuity in the loop, following operation of the associated switch and for producing an electrical condition in the loop which is indicative of switch operation. A control circuit 7 is arranged to respond according to the condition produced and produce an alarm characteristic of the condition.

Abstract: Several arrangement in which several measurement sources (fire alarms) are connected in parallel to a two-wire line. The supply voltage for the measurement sources is simultaneously fed through this line. Here, a measurement is formed by switching a measurement shunt circuit into the two-wire line, to generate measurement pulses, where the switch-in process is controlled by a local pulse generator. Each measurement source is provided with a pulse generator, and all these pulse generators operate at frequencies of the same order of magnitude. A monitoring circuit, at the far end of the two-wire line, is switched through by a pulse generator whose frequency is significantly lower. The pulse duration of the monitoring pulses is no longer than the pulse pauses of the measurement pulses.

Abstract: In an automatic remote meter reading system, a tamper protection circuit (101) provides an alarm signal at a central station upon the disconnecting or tampering with a remote utility meter (100). Tamper protection is provided for the meter and for the transmission line carrying energy usage information to a transponder (500) such that any interruptions of the circuit path causes an alarm to be generated. The circuitry includes a remote resistance (132) associated with each meter to be protected. The value of the remote resistance is continually compared with a resistance (110) having a given value within the tamper protection circuit such that for any changes in the value of the remote resistance, an imbalance in the tamper circuit occurs and the alarm signal is generated.

Abstract: In a remote meter reading system, a tamper protection circuit provides a warning at a central station upon the disconnecting or tampering with a remote utility meter. Tamper protection is provided for the meter and for the transmission line carrying energy usage information to a transponder (500) such that any interruption of the circuit path causes an alarm to be generated. The circuitry includes an encoder (302) associated with each remote meter (300) to be protected and a centrally located decoder (350) for receiving the signal transmitted by the encoder. When usage information is not being transmitted, the encoder is considered to be in a quiescent state providing a pulsed carrier signal to the decoder. For the transmission of usage information, the encoder modifies the pulsed carrier signal by causing a single pulse of a greater period to be superimposed on the carrier and transmitted therewith over the line to the decoder.

Abstract: Tire pressure monitors are incorporated in vehicles having penumatic tires (14) to continuously or periodically measure the air pressure within the tires and to alert the driver should the pressure in one of the tires fall below a predetermined value. A self-contained battery powered rf transmitter unit (10) is affixed within the drop center (22) of each wheel (12) and includes a pressure sensing switch (84). The battery is contained within a housing (20) mounted to the external surface of the wheel adjacent a fill valve (30) through which electrical wires (50) are routed to the transmitter (11). The transmitter emits a pulse every 33 seconds when the air pressure within the tire is above a prescribed value. A receiver (13), located in the passenger compartment of the vehicle, receives the signal(s) from the transmitters and counts the number of signals received over a given time period established by an internal pulse generator.

Abstract: A photoelectric barrier comprises an emitter emitting a movable modulated beam which scans periodically at a high rate an area to be protected. The beam is then redirected to a photoelectric receiver supplying the signal deactivating the machine controls. The barrier also comprises a circuit generating pulses which are effective to suppress some of the pulses emitted by the photoelectric emitter in order to monitor the machine operation during scanning, the suppression pulses being produced by detecting the correct rotation of the scanning motor.

Abstract: In an alarm control system for protecting a premises, a four conductor bus line leading from a master control station is extended about the interior perimeter of the premises. Sensors positioned near each port of entry to be monitored are connected in parallel relationship to the bus line, as is at least one remote station for manually arming, disarming or activating the system. Each sensor comprises a biased reel carrying line secured to window, door, screen, or the like. Disturbance of a sensor causes a magnetically responsive switch therein to generate a pulse triggering circuitry within the control station to activate the desired alarm device for a predetermined period of time. The system then resets automatically to an armed or ready condition to continue protecting the premises against subsequent intrusions. Preferably, the lines in the sensors are of a thermoplastic material so that the system is also activated by abnormally high temperature in the event of fire.

Abstract: Line security apparatus for a direct-wire alarm system utilizes a transmitter at the remote premises to impose on the direct current a small amplitude carrier frequency which is on/off modulated by a clocked, continuous progression of pseudo-random digital bits. A receiver, tuned for the carrier frequency, is utilized at the monitoring station to recover the progression of digital bits, if received at the monitoring station. A microprocessor at the monitoring station produces an identical and initially synchronous sequence of digital bits, compares the produced sequence to the progression of bits received, and effects a temporary alarm signal indicating that the line security is disrupted if the bits do not correspond. Because the lack of correspondence may be due to deviations of the transmitter and microprocessor clocks, the microprocessor seeks correspondence by shifting the produced sequence and, if successful, continues the comparison as shifted.

Abstract: In response to oscillator output pulses, a sample pulse generator supplies sample pulses to a fire sensor. In response to the sample pulses, the fire sensor produces a fire sensor signal. A judging circuit receives the fire sensor signals and, if they exceed a predetermined level, produces a judging pulse having a longer pulse duration than the oscillator pulses. This judging pulse is used to trigger an alarm signal. A monitor circuit consists of an AND gate and an OR gate. The AND gate receives as inputs the oscillator pulses and the judging pulses. The OR gate receives as inputs the output of the AND gate and the sample pulses. The output of the OR gate constitutes a monitor pulse that allows the simultaneous monitoring of three conditions, as follows:(1) Lack of a monitor pulse indicates equipment failure.(2) A monitor pulse with the same waveform as the sample pulse indicates normal operation (i.e.

Abstract: Radiation detection apparatus is disclosed including a first detector (6) for detecting radiation at a wavelength which is preferably in the infra-red region, and a device for sensing the presence of an obturating element (11), which element acts to prevent operation of the first detector. The sensing means includes a transmitter (14) which transmits a signal at a second wavelength, and a second detector (15) responsive to and arranged to receive the signal in the presence of the obturating element, preferably by reflection of the signal from the element. An alarm (10) may be activated in response to detection of radiation or of the transmitted signal.

Abstract: A security system for supervising the integrity of a communication line having a supervising apparatus which generates first and second random signals, compares these first and second randomly generated signals to provide a third signal and compares this third signal to a fourth signal, and a transponder, also connected to the line, which compares the first and second randomly generated signals to provide the fourth signal to the communication line. The use of randomly generated signals increases the difficulty of breaching line security such that, when the supervisory apparatus detects a difference between the third and fourth signals, it can provide an appropriate alarm, indication, or control.

Abstract: A plurality of selectively switchable loads can be addressed from a central station over a ring bus system which has at least a clock bus and a control bus. The central station includes a timing counter which sends signals, for example in groups of pulses, on selected buses forming selection cycles to address specific loads and control signals to separate sequential selection cycles. These signals can be decoded at the receivers. To ensure operator supervision of proper operation of the system, a pulse interrogation stage is connected to at least the clock bus of the bus system and responsive to the occurrence of pulses thereon, and providing an alarm output or warning signal, possibly operating a warning device if the pulses do not occur as they should.