Abstract: A passenger detection system for detecting seating status of a passenger on a seat of a vehicle in which structure of electrodes placed on the seat is improved, is proposed. A plurality of electrodes are placed apart on the upper side of the seat, and a weak alternating electric field is generated between a transmission electrode, selected from the electrodes plurality of and reception electrodes other than the transmission electrode, and displacement currents passing in the reception plurality of electrodes, caused by the weak alternating electric field are detected. The seating status of the passenger on the seat is determined by analyzing the detected displacement currents. An electrode structure is preliminarily formed by fixing the electrodes apart on an electrical insulating base material, and the electrode structure is placed between a cushion material and a covering material of the seat. Preferably, the electrode structure is fixed to one or more components of the seat.

Abstract: A motion detector of an alarm system has a microwave sensor and a passive infrared sensor, and includes signal processing logic for initiating an anti-masking evaluation upon detection of certain conditions. The detector then samples the sensor signals and compares the signals to a series of possible outcomes. Some of the possible outcomes represent masking conditions, while others represent normal conditions. A match with masking conditions results in an alarm signal being generated.

Abstract: In a configuration, a received radiation is converted into a storable secondary energy by a transducer. From the stored secondary energy, a nonlinear element of the configuration generates a radio-frequency signal. A coding element impresses an information item on the radio-frequency signal to generate a response signal. The impressed information can be information on the value of an environmental parameter detected by the coding element, which, in turn, can be a physical quantity or type and/or concentration of a substance.

Abstract: A method and apparatus for detecting for detecting intrusions, such as intrusions through a door or window of a room, in a manner which ignores movements in other adjacent regions, is provided.

Abstract: A motion detector based on mirrored optics for use in decorative lighting fixtures. The motion detector includes a mirror assembly that may be disposed within decorative elements such as saucers and chimneys that are common elements of lighting fixtures. Apertures are defined in the decorative element to admit infra-red radiation, which impinges on the mirror assembly. The mirror assembly comprises a plurality of opaque elongate members that are azimuthally spaced about a central longitudinal axis in such a way as to define an alternating sequence of open elongate slots and opaque elongate members. Each elongate member is formed with a mirror face on its inner surface which is generally facing the central longitudinal axis, and a PIR sensor is also disposed at the longitudinal axis.

Abstract: A motion detector assembly for a decorative lighting fixture that conceals the presence of the motion detector in a decorative element integrated into the design of the lighting fixture and that uses only mirrored optics instead of Fresnel lenses. The motion detector assembly includes a housing having a decorative external appearance harmonious with the style of the lighting fixture and forming an integral part of the lighting fixture. Included within the housing are a mirror assembly and PIR sensor. The mirror assembly includes a number of mirror faces that define a number of monitored zones in the field of view. Each respective mirror face defines an optical path in which radiation admitted through an aperture in the housing from an associated zone is directed to the sensor solely by the respective mirror face without the need for secondary mirrors or auxiliary lenses to complete the optical path.

Abstract: An infrared motion sensing apparatus mounted within the canopy of a decorative lighting fixture where the apparatus may be vertically adjusted. The apparatus comprises a pyroelectric infrared sensor located in a stationary base. Mounted over the sensor and movable in a vertical direction is a Fresnel lens array. The array is mounted to a frame that is constrained to ride on the base in a vertical direction in response to the rotation of a screw. The canopy has an opening to allow radiation to be received by the sensor and a second opening for a stem of the screw so that manipulation of the stem may take place without disassembly of any part of the lighting fixture.

Abstract: An alerting device and method to remind personnel of a risk is disclosed. The device has at least two sensors, a logic controller, a power source, and an annunciator that delivers a visual message, with or without an audible alarm, about a risk to a person when the sensors detect the person exiting a predetermined space. In particular, the present invention reminds a person of a security, safety, or health risk upon exiting a predetermined space. More particularly, the present invention reminds a person of an information security risk relating to sensitive, proprietary, confidential, trade secret, classified, or intellectual property information.

Abstract: In an infrared-rays detector, a pyroelectric element detects existence or movement of a human body, and the output signal of the pyroelectric element is converted to a voltage signal. Then, the voltage signal is subjected to waveform analysis. Then, a detection signal is outputted only when a waveform generated by a human body is detected by the waveform analysis. For example, the voltage signal is amplified at two different frequency ranges, and the amplified signals are used for discriminating a signal due to a human body. Then, a noise such as a popcorn noise of the pyroelectric element is prevented to be detected erroneously as generated by a human body.

Abstract: In an autonomous emergency monitoring system, wherein the user need not carry any signaling devices whatsoever, an emergency situation can be reported to an external receiver by voice input via microphones via a communication interface. Further, a monitoring of the person can ensue via sensor systems that can likewise setup an external connection via the communication interface.

Abstract: A dual security system (10) includes one or more motion activated floodlights (12) installed about a premises. Motion sensors (18) are also located about the property. When the system is “armed”, intruder or animal motion sensed by a motion sensor produces a sensor output which causes the floodlights to be turned “on” and illuminate the premises. An audible alarm (14) is wired in parallel with the floodlights so that when the floodlights are turned “on”, a buzzer (20) sounds. Preferably, while the floodlights may remain “on” for an extended period of time, the buzzer alarm is connected to a buzzer time delay (22) which shuts the audible alarm “off” after a predetermined period of time.

Abstract: A system for detecting and tracking movement within a building has a plurality of portable microwave detector units for deploying outside the walls of the building. Each detector unit has a microwave module for transmitting microwaves through the building walls into a monitored area and for detecting radiation reflected back to the unit from the monitored area, and an output device for transmitting an alarm signal from the unit if a shift is detected in the reflected radiation frequency, indicating movement within the area. A receiver unit receives alarm signals from the detector units and produces an output signal for each detector unit currently detecting movement to provide the user with information on the location of any movement within the building.

Abstract: An occupancy sensor is provided that can operate within an extended range of AC and DC input voltages, enabling the sensor to be used in different electrical environments. The sensor draws substantially only an amount of current required by the sensor at the moment, which reduces power waste. The sensor includes a relay that de-energizes when occupancy is sensed and energizes when occupancy is not sensed. This reduces peak sensor current, permitting the sensor to maintain a more constant average current. A shutdown mode is provided to prevent sensor damage or destruction should excessive output current be drawn from the sensor. The sensor also includes a second output at which occupancy signals are provided when an occupancy signal is present at the first output.

Abstract: A detection system and method are capable of reducing the occurrence of false alarms and detection failures by compensating for variations in the amplitude of a detection signal generated by a PIR sensor. An adaptive threshold can be used that varies according to ambient temperature of the detection area and the frequency of the detection signal. Comparison of the detection signal to the adaptive threshold allows compensation for temperature-and/or frequency-induced variations in detection signal amplitude. The adaptive threshold can be configured for standard detection area conditions or calibrated for conditions at the installation site. Relative measurement and adaptive sampling techniques also can be used to compensate for the presence of low frequency shifts in the detection signal. Such techniques can provide an accurate representation of signal amplitude relative to a threshold amplitude despite differences in absolute signal magnitude.

Abstract: The presence detector has a passive infrared sensor for detecting the presence of persons in a room, an image sensor operating in the visible spectral range and an electronic evaluator for the evaluation of signals from these sensors. The signal from the passive infrared sensor is used to actuate the image sensor and, if necessary, to switch on the room lighting. Once activated, the image sensor is used to detect both movement and occupancy of a space being monitored. Application of the presence detector for the “on-demand” activation and/or control of conditioning facilities of a room, wherein the signals of both sensors are used for the control of the conditioning facility.

Abstract: An occupancy sensor and an automatic dimmer are connected in series with a light source. The detection of motion in the viewing area of the sensor starts the automatic dimmer which moves from its minimum brightness level to its maximum brightness level. One embodiment of the invention includes a key which can be operated to stop the automatic dimmer at some brightness level below the maximum brightness level which is reached if the key is not operated. A second embodiment provides a presetting device whereby the brightness level can be preset. When all motion in the viewing area ceases the automatic dimmer returns the brightness level to the minimum level at a slow rate.

Abstract: An intrusion detection system for detecting objects entering a particular region is comprised of a transmitter, receiver and cable assembly, wherein the transmitter and receiver are connected at opposite ends of the cable assembly. In a first embodiment, the cable assembly is comprised of a transmit and receive cable pair that are aligned at each end and positioned at a constant distance from each other along the length. The transmitter is connected to the transmit cable at one end of the cable assembly, and the receiver is connected to the receive cable at the opposite end of the assembly, with a uniform electromagnetic field established between the cables. An intrusion perturbs the field, which causes a change in the magnitude and/or phase of the received signal. In a second embodiment, the cable assembly is comprised of a single detection cable with the transmitter and receiver connected to opposite ends.

Abstract: A passive infrared sensor uses a modified lens or mirror to vertically elongate the detection zones in regions close to the sensor. This vertical elongation reduces the signal produced by a small pet, such as a cat, while the greater height of a human intruder produces a larger signal.

Abstract: The infrared detector contains an entrance window for infrared radiation, an infrared sensor with an evaluation circuit and an anti-masking device having an optical transmitter and an optical receiver for detecting phenomena or optical changes immediately in front of the detector and/or changes in the optical properties of the entrance window. The signals of the anti-masking device are evaluated in two channels, wherein one channel responds to temporally limited phenomena or changes and the other channel responds to temporally stable phenomena or changes. A combined evaluation of the signals in the two channels takes place. In the combined evaluation, the channel processing the signals of the infrared sensor is preferably also included. As a result, the infrared detector acquires an increased immunity to false alarms and a higher sensitivity.

Abstract: A tracking and monitoring system directs an infrared sensor toward a heat source such as a human body, and three-dimensionally tracks the heat source, wherein the infrared sensor has four infrared detecting elements appropriately located with respect to a reference point in the field of view for producing respective detecting signals varied in magnitude depending upon the parts of the image of heat source incident on the four infrared detecting elements so that a wired logic circuit controls the attitude of the infrared sensor in such a manner as catch the image of the heat source at the reference point.

Abstract: In an intrusion detection system of the kind which comprises a “leaky cable” or open transmission line and is used to determine the presence of objects, things or people moving in the vicinity of the leaky cable, a transmitting antenna and a receiving antenna, one of which is an open transmission line/leaky cable, are connected to a transmitter unit and a receiver unit, respectively. A control unit controls both the transmitter unit and the receiver unit, and causes the receiver unit to scan a preselected radio band, with the transmitter unit not transmitting, to detect one or more relatively quiet portions of the band in which instant received signal levels are lower than a predetermined threshold. The control unit selects a plurality of disparate frequencies in such one or more relatively quiet portions and subsequently causes the transmitter unit to transmit signals by way of the transmitting antenna at the disparate frequencies.

Abstract: A device having an image-providing sensor, hereinafter designated as “image sensor,” operating in the visible and near-infrared range, an thermal image-providing sensor, hereinafter designated as “thermal-image sensor,” operating in the thermal radiation range and having a lower resolution than the image sensor, and an electronic evaluation system. The evaluation system determines whether one or both of the signals generated by the sensors are used for determining whether an alarm condition exists. As a result, the detectability of low-contrast objects is increased, the false alarm rate is reduced, and object classification is made possible.

Abstract: A modular safety switching device is set up such that various signaling devices in a set of possible connectable signaling devices can be connected. In this case, a typical combination of inputs and outputs that are used is provided for each signaling device. The nature of the connection of the signaling device is unique for each signaling device within the set, by which the safety switching device can identify during startup, on the basis of the electrical connections that are made, which type of signaling device is connected and what function is required for identical signaling devices. The safety switching device automatically changes itself to the required operating mode in accordance with this association.

Abstract: A passive infrared detection system which has a wide angular field of view and a flat or nearly flat front surface. Input optical elements direct and/or focus incident peripheral infrared radiation onto one or more internal Fresnel lens arrays and/or a sensitive area of a detector, including radiation having incident angles of less than about 30°. Because of the absence of protruding elements improved performance and greater functionality can be obtained by employing larger or multiple infrared input windows and/or opto-electronic sections without degrading the aesthetic appearance of the unit.

Abstract: Zones of a passive infrared (PIR) motion detector lens are staggered at close range to provide for pet immunity. In a dual sensor, dual lens configuration, the sensor signal is acted on to generate an alarm only when the sensor signal is simultaneous, indicating that an infrared emitting object big enough to cross both staggered zones of a zone pair has been detected. To further enhance sensitivity and immunity to noise, two dual element PIR sensors are arranged in opposite polarity with their elements vertically parallel. The sensor output is simultaneous and of opposite polarity, and noise can be suppressed by blocking like-polarity signals.

Abstract: Occupancy sensors are presented that include a flat lens for focusing detecting beams into narrower, longer range beams than those of conventional curved lenses. A sensing circuit generates a detecting beam that is substantially perpendicular to the flat lens. The flat lens has a plurality of lens segments that provide long, intermediate, and short range sensing beams. To facilitate positioning of an occupancy sensor, the sensor includes a plurality of indicators that indicate the sensor's long and short range sensing limits. An override timer circuit is provided that upon activation sets the occupancy sensor in occupancy mode for a predetermined time period. A warm-up timer circuit is also provided that upon power-up automatically sets the occupancy sensor in occupancy mode for a predetermined warm-up period. These occupancy sensors are well-suited for environments with long aisles, high ceilings, and high intensity discharge lighting.

Abstract: A hazard warning system for warning personnel of potential peril within a specific warning zone, the system including a variable, ultrasonic, and/or infra-red directional transmitter directed to focus on and around a specific hazard and a receiver having both audio and visual warning indicators worn by the worker. Workers outside the warning zone or field not receiving the warning are therefore not immunized by visual and audible signals which are not pertinent to their safety. The warning system further utilizes distance measuring circuitry to automatically determine the distance from the transmitter located on an evaluated crane boom to ground or deck. The distance measurement is then micro processed to maintain a prescribed infra-red field around a suspended object regardless of the boom height. A further embodiment utilizes the technology for a portable signal generator apparatus for attachment to a moving load or vehicle, the warning zone or field may be directed and varied in size and range.

Abstract: A method for determining if a motion detector is in a masked condition at the time power is applied to the detector. When power is first applied to the motion detector it enters a mask detection state which runs concurrently with activity and alarm detection routines. Any infrared motion that is detected after the detector has warmed up and stabilized will terminate the mask detection state. If a predetermined amount of microwave Doppler sensor activity is detected within the field of view without detection of infrared activity, a mask condition is declared.

Abstract: A dual-sensing intrusion detection device for detecting an intruder comprising a PIR sensor and a microwave sensor. The device comprises PIR processing means and microwave processing means, means for summing the processed PIR signal with the processed microwave signal to generate a summed signal, and means for comparing the summed signal to a sum threshold value to determine if an alarm condition exists. The sum threshold value is selected for optimal discrimination between a human intruder and an animal presence. An additional feature of the intrusion detection device is the generation of a PIR difference signal. This feature allows the device to compensate for the limited bandwidth of the PIR sensor and to be more sensitive to a human intruder. The processing of the sensor signals includes an integration technique that sums the amplitude values of the signal and causes the sum to decay at a slow rate.

Abstract: A housing assembly includes a combination lens and window retainer, an inner optical lens, an outer optical window and a front cover. The retainer includes a middle body structure, a pair of side wing structures, an inner seat and an outer seat. The middle body structure has opposite lateral sides, interior portions and exterior portions. The side wing structures are attached to and extend in opposite lateral directions from the opposite lateral sides of the middle body structure. Each side wing structure has exterior portions. The inner seat is defined on the interior portions of the middle body structure. The outer seat is defined forwardly of the inner seat on the exterior portions of the middle body structure and of the side wing structures. The inner optical lens is mounted to the inner seat of the retainer. The middle body structure and side wing structures together define an opening aligned with the inner optical lens and provides an unobstructed forward panoramic field of view through the retainer.

Abstract: A bicolor indicator is provided for a lighting control system which controllably switches one or more lkighting fixtures on or off in accordance with detected motion, ambient light level and a selected time out period. The indicator indicates when the lighting control system is operating in a bypass on or off mode (i.e., overriding controlled switching based on motion detection and ambient light level) or in an automatic time out mode. The indicator also indicates occurrences of motion detection and whether or not the ambient light level is exceeded.

Abstract: A set of badges is distributed at a party to help attending party-goers "break the ice" with members of the opposite sex. Each girl at the party is given a badge of one type, and each boy is given a badge of another type. Each badge has a light that can blink, but it is normally off. Each badge transmits a contact signal that is picked up by any opposite-type badge that is in proximity with it. If the two badges blink, indicating a match, the facing boy and girl must start talking to each other. Either both badges will blink or neither will, but whether or not they blink is based on chance. Each party-goer is given a hidden remote control which, when turned on, increases the probability of the lights blinking. Provision is also made for an exchange of personal information via the badges when a match is made.

Abstract: Practical battery operation of radio-frequency proximity readers is made possible by monitoring activity in the RFID reader's sensing field with a secondary detector such as a passive infrared detector, and powering up the RFID reader only upon detection of activity by the secondary detector. The RFID reader is kept to a low duty cycle relative to the secondary detector which is chosen for relatively low power consumption to achieve a net reduction in operating power requirements of the combined RFID reader and secondary detector.

Abstract: A self-contained security system is disclosed. Operatively connected to each other within a single housing are a power supply, a motion detector, a device for arming the security system and a signaling device, such as a siren, all of the foregoing being connected to a control module so that the signaling device is activated when motion is detected while the security system is armed.

Abstract: A motion detection system compares the differences between regions in a reference frame and regions in a subsequent frame to a threshold value. A difference frame is defined containing regions indicating which of the corresponding regions in the subsequent frame exceed the threshold difference when compared to the reference frame. Target and global parameters are defined so that a cluster of regions in the difference frame which indicate above threshold differences, must be greater than the target parameter but less than the global parameter for motion to be deemed to have occurred.

Abstract: Vertical surface protection in a security installation is achieved by detecting disturbances in a microwave beam sent from a transmitter to a receiver, both installed substantially above the ground and adjacent to the vertical surface. The transmitter and receiver have associated beam aerials of extended horizontal aperture of not less than 0.50 meters (20 inches) to mitigate the effects of surface reflection from metal scaffold, plastic sheeting or netting, wooden boarding and brick or stone facing. The aerials are preferably slotted waveguide arrays and the advantages of using circular polarization are shown. Circularly-polarized slotted waveguide arrays are disclosed having a center feed to minimize frequency-dependent beam-spreading.

Abstract: A multifunction sensor device which provides various transducer functions including means for performing temperature sensing, ambient light sensing, motion detection, switching functions and a means to put the device in an on, off or auto mode. The device has utility in environments such as that found in offices, schools, homes, industrial plants or any other type of automated facility in which sensors are utilized for energy monitoring and control, end user convenience or HVAC control. Key elements of the invention include overcoming the difficulty of mounting diverse sensors or transducers within the same device or housing; permitting these various sensors to exist in a single package that can be mounted to a wall in a substantially flush manner; and eliminating the requirement of an air flow channel in the device, thus minimizing any adverse effects on the motion detecting element or sensor as well as providing built in partial hysteresis.

Abstract: An infrared intrusion sensing system comprises a compound lens having a plurality of lines of focus for focusing infrared radiation that enters the system onto a detector, and a window to allow infrared radiation to enter the system and then be focused onto the detector by a set of curvilinear-shaped mirrors. The detector is located near the focal point of the compound lens elements and curvilinear-shaped mirror elements. An enclosure surrounding the detector provides isolation from insect entry and constitutes an insect exclusion enclosure envelope. The enclosure envelope is a protective volume of space for the optical paths between the lens or window and the detector that prevents the entry of objects about 1 mm in diameter or larger which could interfere with the optical paths.

Abstract: An infrared illuminative warning detector including a base seat formed with at least four perforations for two light shades and two detector heads to insert in. A bulb is installed in each light shade. An infrared detector is disposed in each detector head for detecting alien article within a detection range and lighting up the bulb. Each light shade and detector head is disposed with at least one shifting mechanism for freely changing operation position. The light shades and the detector heads on the base seat are able to detect in different directions at the same time to provide a warning and illumination function in the case of intrusion of alien article.

Abstract: A portable alarm system for alerting a central station of an emergency. The portable alarm system includes a central unit for monitoring a desired area and a remote control unit for activating and signaling the central unit. The central unit includes a detector for detecting an emergency situation and generating a signal in response thereto, a processor for receiving the detection signal and generating an alarm signal in response thereto, a receiver for receiving an emergency signal and providing the emergency signal to the processor and an alarm for alerting the central station upon receipt of one of the alarm signal and emergency signal. The remote control unit includes a device for generating the emergency signal upon receipt of a user generated command and a transmitter for transmitting the emergency signal to the receiver of the central unit.

Abstract: An apparatus for inhibiting the theft of an electronic device includes a processor unit and a display device for displaying operational output from the processor. A receiver unit is included within the electronic device and is adapted to receive remotely transmitted signals that are capable of causing the processor unit to at least partially obscure or change the output on the display device after such signal has been received. The electronic device can be any device that produces a visible output. The obscuring of the display output is by overprinting a message informing you that the device is stolen, and more preferred versions include a unique identification code in that message. This enables the authorities to identify the true owner of the article. The receiver can be a receiver of a radio pager. Upon noticing the theft of the device the owner alerts a service provider who activates the receiver unit.

Abstract: An intrusion detection assembly including an intrusion detector including an inner housing, a detector disposed within the inner housing and a lens for focusing light from outside the inner housing onto the detector, and an outer housing which is generally sealed from the outside and defines a window which is generally transparent to light which is detected by the detector, wherein the intrusion detector is spaced from the window so as to define a region of high sensitivity between the lens and the window which is sealed from the outside environment.

Abstract: A temperature and passive infrared sensor module in which a temperature sensor is mounted so as to not be adversely affected by heat generating electrical components of the sensor module. One embodiment comprises a wallswitch-mounted unit which is designed to be mounted in a wallswitch electrical outlet box with a semi-cylindrical front of the sensor projecting forwardly therefrom. A top section of the projecting semi-cylindrical front has a front curved window, behind which a passive infrared sensor and an ambient light sensor are positioned. A bottom section of the projecting semi-cylindrical front is formed by a removable clip-in door which is provided with air flow vents in a bottom surface and also in projecting front and side surfaces thereof to provide a circulating air flow around a temperature sensor.

Abstract: A multiple sensing technology-based occupancy sensor. Ultrasonic and infrared sensors are used to produce first and second occupancy estimator signals that are combined using a fusion based detection algorithm to produce a combined estimator signal. The combined estimator is then used to switch electrical loads when the combined estimator signal is above a predetermined threshold. The result is an occupancy sensor that has a very high probability of occupancy detection and a low probability of false tripping. In addition, infrared sensitivity is adjusted based upon an estimation of the background noise in order to minimize the occurrence of false tripping.

Abstract: A portable security system 10 includes a control circuit 12 electrically connected with a motion sensor 14, an audible alarm 16 and a visual alarm 18. These components are held within a housing 20 which has a standard light globe/tube electrical connector 22 attached to one end 24 for allowing connection to mains power through a corresponding standard light globe/tube socket. A standard light globe 26 is demountably connected within the housing 20 to illuminate an area in the same manner as if the globe 26 were connected directly into the socket which receives the connector 22.

Abstract: A passive infrared motion detector that creates a detection pattern with non-diverging insensitive zones. The sensing elements are of alternating polarity and each has a width w. An optical collection system directs infrared radiation onto the sensing elements. The sensing elements are separated by a distance equal to an integer multiple of width w, with the integer being at least two. The optical centers of the optical collection system are separated by an integer multiple of width w, with the integer being at least two. The arrangement of the optical centers and the sensing elements results in a detection pattern with non-diverging insensitive zones, with the insensitive zones having a negligible width.

Abstract: A computer monitor system including an infrared motion detecting switch that deactivates the monitor after a predetermined delay during which no movement is detected in the vicinity of the monitor. The system is designed to prevent damage to the screens through excessive use.

Abstract: A detector that can detect an obstacle in a detection field with simple configuration and at low cost is provided. In the detector 10 having a base 11 to be mounted on a ceiling, a wall, or the like, a sensor section 12 which is mounted on the surface of the base, and a cover which is mounted on the base so as to cover the sensor section, the detector 10 is configured such that a obstacle detection sensor 20 for detecting a change of reflectance on and around the surface of the cover can be provided outside the cover 13. The obstacle detection sensor 20 includes light emitting elements 25 and 26 for emitting light to locations on and around the surfaces of the cover, and a light receiving element 24 for receiving reflected light from those locations.

Abstract: A system and method for detecting an intruder into an area to be guarded is provided. The system includes a plurality of detection units, each of the plurality of detection units having at least one infrared sensor and having a first field of view external to and directed generally along the perimeter, and located within the area to be guarded. The infrared sensor may be a passive sensor. The detection units include a camera for recording intrusion within a second field of view and a controller. The controller is responsive to output of the infrared sensor, for determining when an intruder has entered the first field of view, whereupon an operator activates the camera.

Abstract: To generate an alert signal indicating that an unauthorized subject is in a first region within seven feet of a passageway, a radio transmitter is worn by the subject and received by a receiver at the passageway. A second signal is generated upon satisfaction of a second condition, such as an open door at the passageway, which second signal indicates the likelihood of the subject passing through the passageway. A first display indicates if the first signal is present and a second signal if the second condition occurs.