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

Abstract: A sensor connection apparatus for connecting a plurality of sensors to a process controller having a bus for transferring information, wherein each sensor produces an output corresponding to a sensed condition, includes a respective sensor cable that can be connected at one end to each sensor; a concentrator having each of the sensor cables connected thereto; the concentrator being connected to the bus; the concentrator comprising a circuit for producing for each sensor and associated sensor cable connected thereto a first signal in response to the sensor output and a second signal that corresponds to a sensor cable condition; the circuit further operating to couple the first and second signals for each sensor connected to the concentrator onto the bus for access by the process controller. In one embodiment, the concentrator transmits data to the process controller using a standardized communications protocol, such as CAN, using a microcontroller and transceiver.

Abstract: A motion detecting system is disclosed where the signal from the transducer is analysed in a manner to distinguish between actual motion indicative of an intruder, typical noise expected for the area under supervision and the transducer and a signal which indicates a trouble condition (circuit failure, masking, or other trouble condition having a known signal signature). The system samples the signal to provide a simplified representation of the actual signal. The results of the sampling process for a given sample period allows good assessment of the actual conditions of the supervised area. In a preferred embodiment a host of experiment segments are compared within the sample period for change therebetween with the amount of change accumulated for the sample period. This measure of change particularly at different magnitude levels provides a reliable basis for assessing alarm and trouble conditions.

Abstract: Early fire detection and extinguishment is provided by a plurality of fire etection units, each associated with a localized portion of a protected space and including condition sensors specifically appropriate to the environment of that localized portion of a protected space by a selected combination of condition sensors. A fire alarm annunciator and at least one controlled fire extinguishment system portion, or a stand-alone fire extinguishment system, is provided for each fire detection unit. A central control unit preferably includes a profile detector which evaluates outputs of one or more condition sensors over time to reduce false alarm rates while increasing sensitivity to early stage fires.

Abstract: A remote monitor alarm system monitors discrete alarm and analog power supply voltage conditions at remotely located communications terminal equipment. A central monitoring unit (CMU) is connected via serial data links to each of a plurality of remote terminal units (RTUs) that monitor the alarm and power supply conditions of the remote terminal equipment. Each RTU can monitor and store condition information of both discrete alarm points and analog power supply voltage points in its associated communications terminal equipment. The stored alarm information is periodically transmitted to the CMU in response to sequential polling of the RTUs. The number of monitored alarm inputs and permissible voltage ranges for the analog inputs can be remotely configured at the CMU and downloaded into programmable memory at each RTU. The CMU includes a video display, a hard disk memory, a line printer and an audio alarm for communicating and storing the alarm information received from each RTU.

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: 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 arrangement and method for processing signals from infrared microwave and/or ultrasonic intrusion detectors is disclosed which allows the signal to be processed at different amplitude levels to recognize different signal characteristics. This capability to analyze the signal at different values allows further customizing of the system for particular applications and provides information useful in recognizing and dealing with unwanted signal changes typical of the environment which can effect the reliability of the alarm criteria and/or a trouble condition criteria. An assessment of the environment in a preferred aspect allows customizing of the alarm criteria to take into account the operating environment of the particular sensor or sensors. The system also accommodates increasing the effect on certain portions of the signal when considering the net overall effect of the signal.

Abstract: A voltage level detector circuit comprises an amplifier for amplifying the electrical output signal from a detection device, a pair of comparators for comparing the amplified electrical output signal with a respective threshold signal, wherein each comparator is adapted to change its output state when the amplified electrical output signal exceeds the respective threshold signal, and a pair of threshold processors responsive to a superimposed noise or interference component of the electrical output signal from the detection device, or of an amplified version thereof, and adapted to provide the comparators with respective threshold signals which vary with the superimposed noise or interference component, so as to maintain a relationship between the amplified electrical output signal and the threshold signal which is substantially independent of the superimposed noise or interference component.

Abstract: A detector supervision system usable with detectors or sensors formed with a removable head and a surface mountable base includes an energy storage device which is carried on each base. The energy storage device is either a capacitor or an inductor, and is coupled to one or more of the terminals of the base. A conducting spring member is also carried on the base, attached to one of the terminals. The spring member is in a first position when the head is attached to the base. The spring member moves to the second position in response to the head being removed from the base. Detection circuitry can detect the presence of one or more energy storage devices which are switched into communication lines between detector bases in response to one or more of the heads being removed. The detection circuitry can signal a central control panel that one or more of the heads has been removed from a respective base.

Abstract: A system for analyzing the operating conditions of electrical apparatus in order for the aged to check the change and abnormal state of life and for the external institute to check the safety of the houses or homes and so on. The data of standard power spectra of particular consumption current for each apparatus are stored in the memory of the system. The electrical signal detected from the wiring conductor is converted into a digital signal by the preprocessor and undergoes fast Fourier transform at the processor so as to be converted into an extracted power spectrum. If the extracted power spectrum includes a particular one of the standard power spectra as a result of comparing this spectrum with the standard power spectra, the operating conditions of that apparatus are stored in the memory with lapse of time.

Abstract: A method and apparatus is provided for monitoring a variable in a system. Actual values of the variables are sensed to produce sensed values. An initial threshold is set below an initially sensed value by a predetermined difference. Thereafter, the threshold is selectively maintained constant and adjusted to follow below the sensed values by a difference which is a function of the sensed values if the sensed values remain constant or increase, with the threshold remaining constant if the sensed values decreases. The threshold is compared with the sensed values and an indication of an unsatisfactory quality is provided if the sensed values fall below the threshold.

Abstract: An infrared motion detection device for detecting the presence of a target object including special circuitry for reducing false alarms. In particular, coupling circuitry is interposed between signal processing circuitry and comparator circuitry, which serves to match the baseline level of the signal from the signal processing circuitry with the baseline level of a threshold or thresholds defined by the comparator circuitry. The coupling circuitry may be implemented in a particularly simple manner, which reduces the manufacturing cost of the circuitry and the device.

Abstract: A drive current for driving actuators is generated based on a first digital signal comprising n-bit binary data which is supplied from a microprocessor and it is applied to an excitation coil. The drive current is supplied to the exciting coil and is converted into a voltage which is then converted into a second digital signal comprising n-bit binary data. The binary data of the second digital signal is compared with the digital data of the first digital signal to detect an alarm condition. Furthermore, the second digital signal is compared with first and second reference value to set plural alarm conditions.

Abstract: An interface for a supervised multiple input, audible warning system is disclosed. The interface continuously monitors or supervises a plurality of circuits between a control unit and an alarm unit for electrical faults. Each circuit represents a separate alarming condition. All the circuits are coupled to but normally isolated from each other and a common circuit for driving a piezoelectric device. The isolation is accomplished by means of a semiconductor switch normally reverse biased. The semiconductor switch prevents the supervising current of one circuit from driving the piezo by isolating all possible flow paths to all circuits without current flow in the alarming direction. Upon sensing an alarming condition, the direction of the current in the alarming circuit reverses resulting in forward biasing the semiconductor switch. The current in the alarming circuit, no longer isolated from the common circuit, actuates the common circuitry necessary for generating the audible warning.

Abstract: A fire monitoring system detects a plurality of types of detection information using a plurality of fire phenomenon detectors for detecting physical quantities caused by fire phenomena or using a plurality of detectors each including at least one fire phenomenon detector and at least one environment detector provided in association with the fire phenomenon detector. The plurality of types of detection information undergo consolidated signal processing for obtaining one or more types of fire information for realizing fire monitoring.

Abstract: First sensors measure physical quantities correlated with the heat release value of a fire source, and second sensors measure physical quantities correlated with the amount of the product of burning. At least a pair of one first sensor and one second sensor are arranged in a zone to be monitored. A first threshold of high sensitivity and a second threshold of low sensitivity are set at the first sensors. A third threshold is set at the second sensors. A pre-alarm is given only when the level of signals from the second sensors exceeds the third threshold. A fire alarm is given when the level of the signals from the second sensors exceeds the third threshold and when the level of signals from the first sensors exceeds the first threshold. The outputs from a plurality of such sensors detecting different objects, such as heat and smoke, are processed in the manner in which these outputs are combined together to reliably detect fires and to give a fire alarm.

Abstract: A fire detector system including ionization smoke detectors (7) is provided with improved false-alarm protection. The system includes an ionization chamber (1) with a radioactive source (10), connected in series with a resistor (2) between power supply lines (8, 9), and circuitry (11, 28) for switching the operating voltage of the ionization chamber between a normal operating value (Ut) chosen for maximized detector sensitivity, and an elevated value (Uh) for operation at current saturation. Comparisons involving the ionization currents through the ionization chamber at the two operating voltages are used not only to recognize a condition of partial shielding of the radio-active source (due to condensation, for example), but also to detect smoke under such conditions.

Abstract: A circuit including a sender providing a sender output signal responsive to a vehicle parameter, circuitry for providing an adjustable reference, circuitry for comparing the output signal to the adjustable reference and providing a comparison output signal therefrom, an up/down counter for filtering the comparison output signal, and circuitry for providing an indicator control signal in response to the filtered output signal and for controlling the adjustment of the adjustable reference, provides a signal to a vehicle operator that is both filtered and has hysteresis to minimize repeated switching of the signal between two states.

Abstract: In an ultrasonic object detecting apparatus which detects the presence of an object by emitting ultrasonic tone bursts and by receiving the reflected wave, an attenuator is provided at the rear stage of a reception and amplification circuit and an attenuation control circuit for controlling the attenuation in the attenuation circuit is added so that the attenuation is increased at a timing when a reflected wave from a short distance object is received and the attenuation is decreased at a timing when a reflected wave from a long distance object is received. An object in a wide range from the short distance to the long distance may be thus stably detected.

Abstract: An electromagnetic proximity sensor for car security systems includes an electromagnetic wave radiating section adapted to oscillate in a predetermined high frequency range to outwardly radiate an electromagnetic wave; a clutter component extractor for extracting a low frequency clutter component generated in the electromagnetic wave by the approach or movement of an object; a level comparing section, to which is supplied a low frequency clutter component signal corresponding to the extracted low frequency clutter component so as to be compared with a predetermined reference level and which is adapted to emit a sensor signal when the clutter component signal supplied is beyond a predetermined level; and an oscillating operation intermitting section, to which is supplied a pulse signal of a variable duty ratio and of a frequency higher than that of the low frequency clutter component and which is adapted to intermit the oscillating operation of the electromagnetic wave radiating section on the basis of this pu

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 system and method for establishing an alarm threshold for each member of a plurality of detectors or sensors includes storing a value returned from each detector indicative of a clear air condition. A second value returned from each detector indicative of a test condition is stored. The stored values are combined with a common detector characteristic value to produce a unique alarm theshold for each detector. The determined alarm thresholds can be stored for subsequent use. Subsequently, a value returned from a detector indicating a current ambient condition can be compared to that detector's previously determined alarm threshold. If the currently returned value from the detector exceeds the predetermined alarm threshold, an alarm condition can be indicated.

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: An automobile theft alarm apparatus for detecting the variation of the inclination angle of the automobile includes: a sensor of a bridge configuration mounted in the automobile for sensing the angle of inclination of the automobile; a differential amplifier for amplifying the output of the sensor; an offset compensating circuit which produces a reference voltage for the differential amplifier by comparing the output of the differential amplifier with a constant value and by then integrating the differential output; an alarm device for issuing an alarm when the output of the differential amplifier exceeds a predetermined value; and a switching device for increasing a time constant for making the total integration time constant for the offset compensating circuit larger than the time constant of the integrating elements thereof by intermittently supplying the output of the differential amplifier to the offset compensating circuit.

Abstract: Methods for detecting an alarm condition includes repeatedly converting an ambient condition into voltage outputs in detector apparatus repeatedly converting the voltage outputs into a series of actual analog values, polling the series of actual analog values to determine an average analog value, repeatedly comparing the difference between the average analog value and the last actual analog value with a predetermined delta-threshold value and indicating an alarm condition when the difference between the average analog value and the last actual analog value exceeds the delta-threshold value. Methods for detecting an alarm condition further includes repeatedly comparing the average analog value with a maintenance threshold value and indicating a maintenance signal when the average analog value exceeds the maintenance threshold value.

Abstract: A fire detection system includes a color video camera, a frame grabber and a computer processor operative to store and examine a series of image frames of the viewed area. Ultraviolet and infrared detectors produce event signals when energy received exceeds predetermined thresholds. The processor then rapidly evaluates the images from the camera to determine bright area objects, their location, edge profile, edge flicker, stationarity and spectral characteristics as well as spectral flicker to confirm a fire event. Finally, the size of a confirmed fire image is measured as a final criterion for the release of fire suppressant material, either in a limited zone within which the fire is located or within the entire facility.

Abstract: Method and apparatus for periodically checking the ground path resistance value of a crash sensor connection to chassis ground and determining if the resistance exceeds a predetermined maximum acceptable value.

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 line interface circuit sends two-level signals to a line and receives two-level signals from a line. The two levels of the signals are on opposite sides of a threshold range of levels. For testing the circuit the transmitter is connected to the receiver by a switchable path, and a test signal is produced by the transmitter for reception by the receiver for monitoring the functioning of the circuit. The test signal is of a small amplitude so as not to enter the threshold range of levels). The connections of the transmitter and receiver to the line are maintained during testing. During testing the output of the transmitter is limited in amplitude by a voltage clamp so that it can produce only the test signal.

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: An environmental detection system particularly useful for fire detection and suppression is provided which ensures high reliability in operation and high reliability in preventing false operation. The preferred system includes a microprocessor-based, software-governed, control panel connected to one or more detector loops. Each loop includes a plurality of parallel-coupled, addressable detectors which send analog signals to the control panel representative of an environmental parameter such as smoke obscuration along with reference and identification signals. The preferred system provides automatic calibration and test of the detectors, automatic testing under load of the backup batteries, flexibility in defining the protective scheme, and storage of history information concerning system alarms, and troubles. The preferred system also verifies alarm conditions before actuating an alarm or discharging a fire suppressant.

Abstract: An electronic article surveillance system which is capable of reliably identifying and discriminating between the different signatures of tags and labels which may come to pass in its vicinity, improving the reliability of the system and even permitting the tags and labels to be classified by type, and separately addressed, includes a receiver for detecting signals resulting from such tags or labels which incorporates improvements in its filtering and processing sections. A linear phase (constant group delay) filter is used to more effectively preserve the signal which is received, and thereby improve the signal which is ultimately delivered to the processor which follows.

Abstract: A power status detecting apparatus which is to be applied to a plurality of audio-visual equipments arranged such that currents flowing to AC lines of the respective equipments are detected so as to identify the power condition status of the respective equipments and in which identified information are supplied to a system control apparatus. Thus, system control for a plurality of equipments can be performed more positively and conveniently.

Abstract: A line interruption supervisory device for a fire alarm system is capable of reliably carrying out the line supervision even if the line length is long and/or there is a large number of connected fire detectors. To this end, a terminating capacitor is connected across the terminal of a pair of power/signal lines to which fire detectors are connected. A memory first stores the voltage available on the power/signal lines when the line supervision is requested, immediately followed by the interruption by a cut-off circuit of the power supply to a pair of power/signal lines, and further followed by a comparison of the voltage available on the power/signal lines before the power supply interruption with a line voltage available after a lapse of a predetermined time from the power supply interruption by a line interruption discriminating circuit to determine, according to any difference between these voltages, whether there is an open power/signal line.

Abstract: A signal detection system with dynamically adjustable detection threshold includes a signal detection comparator having a dynamically adjustable threshold which adjusts the detection sensitivity of the comparator from a quiescent value to a value which is dependent upon the value of an event trigger signal, thus anticipating the amplitude of a second, confirming event trigger signal. Additionally, an alarm window timer activated by an event signal which exceeds the quiescent signal detection comparator threshold, assures that an alarm activator will be enabled only after a second, confirming event trigger signal exceeds the adjusted detector threshold, and which occurs during the active period of the alarm window timer.

Abstract: A process control system is disclosed in which process variables are treated as mapped in n-dimensional space, where n is the number of orthogonal directions. Three functions, set, check, and term, provide the link between expected and actual conditions. The check and term functions operate on orthogonal coordinates. Each parameter has a guard band to provide a soft boundary for the parameter.

Abstract: A system for detecting an overheat condition in aircraft preferably includes two control units each connected to eight thermal imaging modules. The thermal imaging modules monitor the cargo by for an overheat condition and if any module detects an overheat condition, the control unit verifies the overheat condition and then triggers an alarm. The control units execute routines to monitor and test their operational status and that of each thermal imaging module. The control units are connected to the aircraft electronics to indicate the location of an overheat condition or any malfunctioning control units and thermal imaging modules. The thermal imaging modules are identical to each other and include an infrared detector, a rotating optical assembly, threshold circuitry and a motor. The optical assembly is rotated by the motor to provide the detector with a conical field of view. The optical assembly focuses the radiation in the cargo bay on the infrared detector.

Abstract: An autodyne microwave motion-detection system includes a supervisory circuit for monitoring the operating status of the microwave energy-producing component of the system. According to a preferred embodiment, the supervisory circuit of the invention comprises a relatively low-cost, "general purpose UHF" diode, i.e. a multipurpose diode commonly used in circuits designed to accommodate UHF frequencies of up to only about 3 Gigahertz. The supervisory diode is positioned within, or in close proximity to, the resonant cavity of the microwave energy-producing element, the latter being designed to produce microwave energy at a substantially higher frequency (e.g., 10.5 Gigahertz). Due to its close proximity to the microwave energy-producing element (e.g. a Gunn diode) and its presence within the energy field produced thereby, the supervisory diode develops a small, but readily detectable, voltage whenever such element is radiating microwave energy.

Abstract: A circuit senses the conditions of control instrumentation such as valves and graphically displays these conditions on a display panel or screen of a console. The circuit also provides signal checking or validation capability monitoring the quality of the instrument condition signals and displaying the quality of the monitored signals on the same console screen.

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: An apparatus and method for combining detection signals generated by intrusion detection systems to provide improved alarm integrity therefor. The apparatus and method have utility with mixed sensor technology and single sensor technology detection systems. In one embodiment, analog detection signals generated by system sensors are combined in an analog multiplier and the resulting decision signal is compared via a unipolar threshold comparator or a window comparator. In another embodiment, analog detection signals are amplitude limited prior to being combined in the analog multiplier. In a further embodiment, analog detection signals are subjected to average value processing such that the decision signal has a value equal to one-half of the sum of the sensor signals. In yet a further embodiment, analog dectection signals are amplitude limited prior to average value processing.

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 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 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 detector for an alarm system receives a disturbance signal and transmits an alarm signal to a remote station. A group of such detectors can be connected in circuit to operate a common alarm. The detector has means (6, 26, 33) for suppressing a first disturbance signal so that only a second and subsequent ones trigger the alarm. There are also means (8, 30) whereby a disturbance signal only of a given length can pass to trigger the alarm. With another facility (38, 43) the detector registers whether it is the first or a subsequent one in a group to be disturbed. The detector is largely embodied on a integrated circuit chip and all these facilities are selectable by making or omitting simple pin connections.

Abstract: Disclosed is a system that can monitor occupied or unoccupied buildings, and annuciate to a distant point, e.g. a digital pocket paper, emergency events such as burglaries, fires, high or low temperature, high or low flow rate in such devices as boilers and many more. The system has a circuit that makes interfacing with most commercial field detectors especially easy, and a circuit that enables the system to easily access telephone lines, so as to transmit annunciation messages.

Abstract: A combustion control system includes a sensor assembly and a process controller, the sensor assembly including sensors for providing output signals indicative of process variables, the process controller responding to the output signals to maintain a desired operation of the process. The process controller continuously monitors parameters of the sensors and provides alarms whenever any of these parameters deviate from setpoint values, the process controller automatically prioritizing these alarms to provide a display of only the most relevant alarms. A housing enclosing the processor controller provides RFI/EMI shielding of the process controller including the attenuation and absorption of the EMI/RFI energy.

Abstract: An improved alarm system and method for use in a fire detection system of the type including at least one sensor for sensing the level of a parameter of a fire condition such as heat or smoke density and which transmits electrical signals indicative of the sensed levels over a communication link. The alarm system and method provides for indicating a first alarm condition by receiving electrical signals from the sensor, keeping time from the time that the parameter reaches a first level, and indicating the first alarm condition when the parameter reaches a second level within a first predetermined time period. The second level has a magnitude greater than the first level. The alarm system and method also indicates a first alarm condition corresponding to a third level of the parameter prior to the third parameter level being reached.

Abstract: A detector for sensing or measuring objects passing a measurement path (5) has a detection element (6), the output signal of which is a function of objects discovered in the measurement path. The output signal is fed to an amplifier and filter circuit (7-9), the output of which is connected to two parallel integration cirucits (11, 12). The integration circuits have time constant (.tau..sub.SH, .tau..sub.L) of different magnitudes, and their output signals are fed to a comparator (13) for obtaining an operative signal indicating the presence of an object in the measurement path, this signal being unresponsive to long-duration fluctuations in the detector's operating conditions, e.g., dirtying of the detection element. The detector includes a dirtiness alarm with the threshold response adjustable to a long-time-constant integrator output.