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: A passive intrusion alarm system having an array of infrared sensing elements arranged and sampled so as to provide a two dimensional thermographic image of an intruder.

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: An infrared detection system having a detector which includes elements of different sizes which are electrically selectable to change the operational range of the system without any change in the associated optical assembly. The detector elements can be of two or more element sizes, and various detector configurations can be employed such as single or dual detector configurations. To provide a constant signal amplitude for the different selected ranges, the gain of the detector circuitry can be adjusted accordingly to provide uniform signal amplitude irrespective of range setting.

Abstract: An improved passive infrared balanced detector is disclosed that reduces false alarm rates induced from random thermal activity and other causes of splitting of the field(s) of view of the balanced detector into distinct and independent regions. The detector includes balanced elements selectively shaped and arranged to provide common mode rejection within each of the regions into which the field(s) of view are subject to being split. The unbalance susceptibility of the novel detectors may be adapted to the particular requirements of the intended applications environment. The susceptibility for unbalance is materially reduced and therewith the alarm confidence level of the detectors is substantially improved.

Abstract: An alarm system uses an area sensor having a piezoelectric film sensitive to changes in pressure. A piezoelectric film with electrodes deposited on opposite surfaces of the film converts changes in mechanical pressure to electrical signals. A signal processor detects the electrical signals and generates an output signal in response. The electrodes could comprise single metalized sheets deposited on each surface. Alternatively, an array or pattern of individually operative electrodes could be provided. An array or pattern of electrodes enables the signal processor to determine the location, motion, and direction of motion of a force generating pressure changes on the piezoelectric film. The alarm system may include a threshold detector sensitive to the magnitude of pressure changes so that an output signal will not be generated unless the pressure change is sufficiently great. This invention is suitable as a floor covering for detecting an intruder walking over its surface.

Abstract: A passive analog equalizer is connected to the output of an infrared detector to provide increasing pyroelectric detector sensitivity with increasing target frequency in order to provide a detection sensitivity which is substantially flat over the target velocity range of interest. An interruptable modulator is connected to the equalized pyroelectric detector signal to shift its frequency upwardly in order to provide negligible drift, fast recovery from transients, and the ability to quickly shut down the modulator when a transient occurs. A transient detector is operative in response to transients in the pyroelectric detector output signal to provide a window during which the modulator is interrupted in order to prevent transient induced false alarms.

Abstract: A control and display system for an electronic security system which comprises a thin flat multilayer panel which provides a touchpad for entry of data and display areas for the selective display of messages and legends. The system is contained within a small wall mounted housing which includes a microprocessor controller cooperative with the panel. The system operates as a data terminal in communication with a master control unit and is operative in response to touchpad actuation for providing data to the remote unit, and it is operative in response to data received from the remote unit for actuating displays and associated annuciators. The system is programmable via the front panel, and input and display modes can be tailored to suit particular operational requirements.

Abstract: The disclosed steerable mirror assembly and cooperative housing for a ceiling mountable passive infrared intrusion detection system of the present invention includes first and second relatively rotatable field forming mirrors cooperative with a focusing mirror to provide first and second substantially curtain-like fields of view at any selected pointing directions through 360.degree. of azimuth. The field forming mirrors have a preselected non-constant radius of curvature selected to provide uniform detection sensitivity at any range within the fields of view of the several curtains. A modular housing is disclosed having cooperative, releasably assemblable components that allows ready in-the-field installation, and subsequent maintenance and troubleshooting. The housing includes a tamper switch that is operative upon an unauthorized tampering with the housing after installation to provide a signal indication of a possible system deactivization attempt.

Abstract: The disclosed ceiling mountable passive infrared intrusion detection system includes a field forming mirror assembly and a focusing mirror assembly cooperative to provide a field of view having plural first vertical curtains, a generally disc-shaped horizontal second curtain, and a generally conical downwardly directed third curtain. In one embodiment, first and second conical field forming mirrors are cooperative with different and spaced-apart spherical focusing mirrors to provide the horizontal curtain and the downwardly directed conical curtain. An unbalanced detector is disclosed that cooperates with the energy pattern received from the conical field forming mirrors to signal intruder presence. In another embodiment, first and second pluralities of planar field forming mirrors are cooperative with the different and spaced-apart spherical focusing mirrors to respectively provide a first plurality of substantially horizontal finger beams and a second plurality of plural downwardly directed finger beams.

Abstract: The motion detector of the present invention, together with associated AC switching circuitry form a lighting control system which turns on room lights when the room is occupied, and extinguishes the lights when unoccupied. The detector sensitivity or threshold is adjusted in response to the previously detected conditions, providing reliable indication of both entry and continued presence in the controlled area, and producing few false alarms. The present embodiment of the invention has two threshold levels of detection, the higher level being used to detect initial entry into the room. After entry is detected, the motion detector lowers the threshold to detect the weaker signals usually occurring for continued presence in the area of the detector. When the occupant leaves the area, the motion detector threshold or sensitivity returns to the original value after a timeout period.

Abstract: The ceiling mountable passive infrared intrusion detection system of the present invention includes a focusing mirror having an optical axis, and a composite field-forming mirror cooperative with the focusing mirror for providing both a plurality of vertical curtains and a plurality of uniform detection sensitivity finger beams defining fields of view in selected azimuthally spaced relation through which an intruder must pass when in motion about the floor of a protected facility. The composite field-forming mirror includes first and second pluralities of selectively-twisted cylindrical facets defining longitudinal axes that individually intersect the optical axis of the focusing mirror at preselected different non-zero acute angles and provide corresponding ones of the selectively azimuthally spaced fields of view of the vertical curtains.

Abstract: Alarm system apparatus and method for optically transmitting information indicative of system operational status from an alarm detection unit to a remote receiver. The alarm detection unit includes a light emitting element for optical transmission of diagnostic and other data to the receiver. The light emitting element is pulse activated in accordance with a specified protocol to optically transmit data serially to the receiver, and the receiver is adapted for decoding of the serially transmitted data to provide an output indication to a system user indicative of detection unit operational parameters. One embodiment of the invention includes a bar graph indicator to provide a visual indication of selected operational parameters as an aid to a user in assessing system performance characteristics.

Abstract: A constant range ultrasonic motion detector features an ambient atmospheric condition sensor which senses the temperature, pressure, and percent relative humidity of the ambient atmosphere and produces therefrom a range compensation signal to adjust the sensitivity of the ultrasonic motion detector for stabilizing the range. The range compensation signal is applied to adapt detector amplifier gain and/or threshold level to the variation between design and ambient conditions. In one embodiment, an analog summing network at the ambient atmospheric sensor outputs provides the range compensation signal and in a second embodiment a microprocessor is operative to provide the range compensation signal.

Abstract: A temperature compensated alarm system includes a temperature transducer operative to produce an electrical output signal indicative of the ambient temperature, an alarm sensor, an electronic processing module, and a plurality of addressable registers for storing alarm threshold limits applicable at the operative ambient temperature. At selected times the electronic processing module reads a value indicative of the ambient temperature and thereupon determines the applicable alarm threshold limits by addressing the respective registers containing threshold limit data for the particular ambient temperature. In one embodiment, two sets of registers are provided; one set of registers containing higher sensitivity threshold limit data and the second set containing lower sensitivity threshold limit data. The applicable threshold data is determined by the state of a user settable switch.

Abstract: A ceiling mountable passive infrared intrusion detection system is disclosed having a mirror assembly providing a first protective curtain which is relatively narrow in the horizontal plane and which substantially encompasses the vertical space of a protected facility, and providing a second protective curtain which is relatively narrow in the vertical plane and which substantially encompasses 360.degree. of horizontal space of a protected facility. A temperature stabilized and shock insensitive infrared detector is disposed along the optical axis and at the focal point of the system to provide electrical signals in response to received radiation from the field of view of the protective curtains. The electrical signals are electronically processed to provide an output indication of intruder presence when in motion about both the floor area and the space between the floor area and the ceiling of a protected facility.

Abstract: A snap-together, passive infrared detector assembly includes a modular passive infrared detector sub-assembly defining an optical cavity. In one embodiment, the passive infrared detector sub-assembly is slidably mounted to a resilient U-shaped housing sub-assembly suitable for high wall or ceiling flush mounting. (An aesthetic cover plate is snap-locked to the U-shaped housing.) In another embodiment, the passive detector sub-assembly is mounted in a plastic housing having an aperture for high wall or ceiling surface mounting. An optical window is snap-locked onto the mouth of the optical cavity in both embodiments. Both embodiments are self-contained and fashioned substantially of a plastic material. The modular passive infrared detector sub-assembly includes an optics and an electronics module. The optics module is composed of snap-together first and second plastic mirrored members having respective arcuate metalized surfaces which define the optical cavity.