Abstract: An apparatus for monitoring and controlling the operation of an electrical power transformer includes a processor with input transducers for providing to the processor inputs indicative of electrical current in a winding of the transformer and ambient temperature outside the transformer. The processor is arranged using an algorithm based upon heat transfer to repeatedly calculate a first prediction, based upon the present values of electrical current and ambient temperature, of a time period before the hot spot temperature exceeds a pre-set allowable maximum and a second prediction, based upon the current value of power, of a time period before the accumulated loss of life exceeds a pre-set allowable maximum. If the shorter time period of the two calculations is less than a pre-set value, for example one half hour, the processor generates an alarm signal and a display counting down the time remaining in the period, together with a second alarm signal at a shorter second time of for example one quarter hour.

Abstract: Occupant sensing system (12) for detecting the presence of an occupant within an automotive vehicle (10) includes a seat belt sensor (14) for detecting a buckled condition of the seat belt. An ignition sensor (24) generates an ignition-off signal. An indicator (30) is coupled to a controller (20), the seat belt sensor (22), and the ignition sensor (18). The controller controls the indicator in response to the seat belt buckled signal and ignition-off signal.

Abstract: A highway lane position detector including a photodetector for determining the existence of highway lines, wherein the detection circuitry maintains its detection ability over a wide range of ambient light conditions from bright sunlight to dim artificial light in ambient darkness, by providing a dynamic resistance element in series with the photodetector wherein the dynamic resistance element compensates for changes in the photodetector due to changes in ambient light conditions to maintain the photodetector in a detection condition (avoiding saturation) regardless of the ambient light condition. In the preferred embodiment of the detector, the dynamic resistance element is at least one reversed biased zener diode. In currently preferred circuitry of the invention, the detector detects the presence of intermittent lane dividing lines and provides an alarm when such lines are no longer detected.

Abstract: A transmitter, which is operated by a battery, wirelessly transmits data including data that represents the temperature T in a tire and data that represents the voltage V of the battery. A receiver judges whether or not the life of the battery is ending depending on the battery voltage V read from the received data. More specifically, the receiver performs the judgment regarding the life of the battery based on a comparison between the battery voltage V and a variable voltage reference value V0, which is selected in accordance with the temperature T in the tire. The judgment regarding the life of the battery is thus accurately performed.

Abstract: A multi-mode electrical device for a communications system exhibits at least two different modes manually selectable at the device. A mode setting switch carried by the device has at least two states. One state is associated with a normal operational mode. A second state is associated with a different operational mode. A movable member carried by the device's housing can be used to select the mode.

Abstract: A system (and method) includes at least one sensor for sensing a presence of a vehicle occupant, and for sensing a dangerous environmental condition within a vehicle, at least one system for emitting a warning based upon the output of the at least one sensor, and a device for transmitting a signal from the at least one sensor to the warning device.

Abstract: A emergency communication device which performs self diagnosing by repeatedly transmitting a weak signal, which can only be received by an antenna, among a plurality of antennas in a fixed time interval. When the weak signal is not received due to the occurrence of an accident, theft or the like, the occurrence of the emergency is communicated to an emergency data receiving center.

Abstract: A wireless detection system for monitoring a predetermined area for an emergency situation. The wireless smoke detection system includes a plurality of detector units strategically positioned throughout the monitored area. Each of the plurality of detector units include a detector for sensing one of a characteristic and condition within a section of the monitored area and generating a signal indicative of the monitored. A signal processor is connected within each detector unit for analyzing the signal generated by the detector and upon determining if the signal is above a predetermined level generating an emergency signal. A transmitter is provided for transmitting the emergency signal to a plurality of receiver units strategically positioned about the monitoring area. Each receiver unit includes an alarm for generating an alarm signal and thereby alert persons to the emergency situation at a position within the monitored area.

Abstract: A system for encouraging good personal hygiene in toilet facilities is provided, including means for detecting the acoustic signal generated by the inrush of water into a toilet bowl to trigger a recorded admonition to the toilet user to cleanse his or her hands.

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.

Abstract: System and methodology for providing real-time call processing services received at a switch in an intelligent network having one or more service nodes having originating switches for receiving a call event. The system includes a platform-independent communication system for enabling communication between object instances executing at service nodes in the intelligent network. An operating system agent object instance executing in an execution environment associated with an originating switch communicates call origination information corresponding to a call event received at the switch to one or more object instances executing in an execution environment provided at a service node in the network; the object instances including a line object instance for maintaining the state of a communications line associated with a call origination, and, a service object implementing methods for performing a service according to a customer request.

Abstract: A multi-function detector has at least two different sensors coupled to a control circuit. In a normal operating mode the control circuit, which could include a programmed processor, processes outputs from both sensors to evaluate if a predetermined condition is present in the environment adjacent to the detector. In this mode the detector exhibits a predetermined sensitivity. In response to a failure of one of the sensors, the control circuit processes the output of the remaining operational sensor or sensors so that the detector will continue to evaluate the condition of the environment with substantially the same sensitivity.

Abstract: An intrusion detector has a housing with an infrared device disposed therein, an infrared sensor, a detector window provided in the housing wall for the passage of infrared radiation from the external space onto the infrared sensor, an element for focusing the infrared radiation incident through the detector window onto the infrared sensor and having a sabotage surveillance device including an infrared transmitter and an infrared receiver. The infrared transmitter and the infrared receiver are disposed inside the housing and the detector window is substantially transparent to radiation emitted by the infrared transmitter. The sabotage surveillance of the detector takes place by measuring the proportion of the radiation reflected onto the infrared receiver from the inside of the detector window and the radiation transmitted onto the infrared receiver from the surrounding space.

Abstract: A monitoring system (10) is disclosed for monitoring the condition of a filter (16) filtering a gas or liquid. Using various sensors, the permeability of the filter is monitored on a continuous basis. A significant increase in permeability, decrease in permeability or rate of change of permeability can lead to an indication of filter failure, such as rupture, leakage, loading and unloading. The system can be monitored by a computer and monitored from a remote location through phone lines and Internet computer systems.

Abstract: A system is disclosed for indicating the status of a person relative to a workspace. A motion detector senses the entry and exit of the person through a entryway of the space and distinguishes the difference between the person's presence when moving and when stationary. An indicator automatically displays a constant green light to announce the person's presence, a flashing green light when the telephone is being used, a flashing amber light for short duration absences, a constant amber light for long duration absences and an intermittent red light and beeper for emergencies. A controller houses a preprogrammed microprocessor, a communications link and three illuminated buttons corresponding in color to the lights of the indicator and functioning in tandem with them. The green button activates the “Do not disturb” display, the amber button the long duration absence display and the red button the emergency alarm.

Abstract: Disclosed is a vehicle security system, in which the vehicle security system comprises a control unit having a central processor or microprocessor, a receiver connected to the microprocessor for receiving signals from a remote transmitter. The control unit has an input interface and an output interface. The input interface is connected to various sensors, and the output interface is connected to the vehicle security devices. A PWM interior light delay is disposed between the door sensors and the input interface to provide a voltage pulse signal with width modulation for a vehicle interior lights such that the interior lights are extinguished gradually for a predetermined time. The user can selectively set the vehicle security system whether the vehicle is provided with the PWM interior light delay.

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: A multi-unit ambient condition detecting system incorporates either a wired or a wireless communication medium wherein the units are in bi-directional communication with one another. Units can incorporate programmed processors and ambient condition sensors such as smoke or gas sensors. In response to detected local ambient conditions, the respective units can transmit messages indicative of the level of sensed ambient condition to other units in the system. The units can maintain running totals of levels of ambient conditions received from other units in the system and combine those received indicators, along with one or more locally generated indicators, to determine that a selected condition, such as fire or gas is present in at least a portion of the region being monitors. Output devices coupled to the communication medium can provide human discernable audible or visible indicators of the presence of one or more selected conditions.

Abstract: A intruder detecting apparatus for detecting a intruder invading an detection area defined in, for example, a window, entrance or apron region in front of one or more wall-mounted paintings includes a first sensor 2X having an detection area 7A defined in the front side of the objects 5 and 6 to be watched and the region upwardly of those objects 5 and 6 to be watched, and a second sensor 2Y having an detection area 7B defined in the front side of the objects 5 and 6 to be watched and the region downwardly of those objects 5 and 6 to be watched. A timer-equipped logic circuit 13 is provided in at least one of the first and second sensors 2X and 2Y. The other of the first and second sensors 2X and 2Y has an output path 17 provided therein for outputting a detection signal a from a detector 10 within such sensor to an external circuit.

Abstract: A passage control device for non-contacting data carriers has an antenna unit (5) with a front wall (12) extending in the passage direction and facing the passageway, the height of said wall corresponding to the different wearing heights of the data carriers, and said wall having disposed thereon at least one antenna (13, 14) for data transmission in the radio wave range, and a turnstile (4) with an obliquely downward pointing hinge pin (8) and barrier arms (10) extending obliquely to said hinge pin. The front wall (12) of the antenna unit (5) extends downward beyond the bearing of the turnstile (4). The turnstile (4) is mounted on the area of the antenna unit (5) on the front in the passage direction (15), and the portion (17) of the front wall (12) extending downward beyond the turnstile bearing extends obliquely rearward. The front wall (12) of the antenna unit (5) is designed as an information surface (18) for optical information.

Abstract: A system which allows the firefighter to monitor a variety of safety related parameters during firefighting activities through audible and/or visual means. The system of the present invention monitors the pressure in the firefighter's breathing system and also monitors ambient temperature and motion of the firefighter. An audible alarm is activated to indicate a potential emergency situation relating to low remaining air time, impending thermal breakthrough or lack of motion of the firefighter.

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 integrated security system includes a plurality of security devices each issuing an alarm signal. A plurality of control units are associated to control the security devices via a communication line. Each security device comprises an alarm storing section for storing alarm signals received from individual security devices as alarm information. An alarm transmitting section transmits the alarm information to all of the control units via the communication line. The alarm information stored in the alarm storing section during a predetermined storage time are transmitted at a time as an alarm notification command to the control units.

Abstract: A security system incorporates a reasoning system and security rules and processes that are designed to be as unobtrusive as the situation permits. Two independent aspects of the system facilitate the enforcement of rules and processes in an unobtrusive manner. First, transponders that can be triggered and sensed from a distance are preferably used to identify both items and individuals. These remotely sensed identifiers are processed by the reasoning system to determine whether each identified item is authorized, or likely to be authorized, to be removed from, or brought into, a secured location by the identified individual. Second, the system continually modifies and optimizes its rules and processes based on assessments of security events. An initial set of rules is created for the security system that, generally, prohibit the removal of secured items from the secured location, except that certain individuals are authorized to remove specified items from the secured location.

Abstract: A monitoring apparatus and method are provided for a communication system in which a central office communicates to at least one end unit using intermediate remote nodes. The remote node receives signals from both the central office and the end units. Each remote node can be equipped with apparatus for monitoring the integrity of paths of the communication system. The monitoring apparatus can include a mixing device that mixes received signals to produce combined signals. The received signals generally include a pilot signal sent from the central office and a data signal sent from the at least one end unit. The state of the communication system is analyzed based on the combined signals. If the combined signals includes only the data signal from the end unit, the path through which the pilot signal was sent is inoperative. If the combined signals includes only the pilot signal, the transmission path from the end unit over which the data signal is sent is inoperative.

Abstract: A system and method to more efficiently exchange information between a service provider, such as a semiconductor company, and its remote equipment units. The system capable of immediately handling a number of information items, each belonging to a different remote equipment unit is disclosed. The system includes a central controller configured for interfacing with a plurality of remote equipment units via a wireless network. The central controller is configured to receive information from each remote equipment unit via a wireless network. This information includes alarm conditions and corresponding requests for repair. Each of the remote equipment units is identified by a unique code which is included in the information transmitted to the computer to identity the source (i.e., identity of the transmitting remote equipment unit). The central controller uses the code of the transmitting remote equipment unit to retrieve the corresponding data record stored in its memory.

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: To monitor a patient, an alligator clip is fastened to the patient by a cord having a length of between five inches and five feet. The other end of the cord is connected to a switch which is activated when the patient moves beyond the length of the cord to cause a message to be announced. A disposable pressure pad is located under the patient and armed by the application of weight to the pad. Upon removal of the weight the alarm is given.

Abstract: In a failsafe method and apparatus for signalling theft for a motor vehicle, an item of theft-signalling information is produced as a function of the signal state of at least one of a plurality of monitoring signals, which are indicative of vehicle states. According to the invention, the theft-signalling information is produced only if the signal states of a plurality of monitoring signals are present in one of one or more prescribed theft-signalling combinations. Each theft-signalling combination comprises one or more signalling conditions, which succeed one another in a specific time sequence and which signalling conditions themselves comprise one or more theft indicative combinations of jointly interrogated signal states of associated monitoring signals.

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

Abstract: An apparent temperature monitor and/or alarm comprises separate sensors that monitor at least ambient temperature and humidity of a location in which an occupant resides. It has been noted that certain elderly and/or poor residents of urban areas may be unable to self-monitor their environmental and health situation, and that use of an apparent temperature monitor/alarm may assist in preventing mortality of elderly occupants or those who are unable to fend for themselves. A system for monitoring a large number of remote locations may also be established and appropriate health or safety personnel may be directed from a central monitoring location to investigate specific occupants or remote locations indicative of unhealthy environmental conditions.

Abstract: The present invention provides a method and apparatus for monitoring the operation of a mobile machine. The machine includes a mobile communicator adapted to communicate with a remote monitoring station. The method includes the steps of receiving a configuration message from the remote monitoring station via a wireless communication link, comparing at least one of a current machine position to the configuration information a current machine time of operation to the configuration message, and sending an alarm message to the remote monitoring station in response the comparison.

Abstract: A system which allows the firefighter to monitor a variety of safety related parameters during firefighting activities through audible and/or visual means. The system of the present invention monitors the pressure in the firefighter's breathing system and also monitors ambient temperature and motion of the firefighter. An audible alarm is activated to indicate a potential emergency situation relating to low remaining air time, impending thermal breakthrough or lack of motion of the firefighter.

Abstract: A fire detection system cross correlates the responses of a temperature and smoke sensing units to achieve early-detection characteristics. The system also performs threshold-type detection on the smoke obscuration, temperature, and rate of temperature rise. If any of the thresholds are surpassed, the same alarm condition will be set. As a result, the detection characteristics of the resulting detector can be no worse than the conventional threshold-only systems. The system advantageously, however, provides for the early detection of fires that satisfy the cross correlation characteristics. Thus, it achieves the best performance characteristics of both approaches.

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: This invention relates to a novel electronic case for carrying credit cards and the like. More particularly, this invention pertains to a novel electronic case which accounts for the credit cards held in the case and sounds an alarm and activates an alert light if one or more of the cards is missing from the case. A portable electronic card carrying case comprising: (a) a case which can be opened to reveal the interior of the case, and closed to conceal the interior of the case; (b) at least one card receptacle housed in the interior of the case; (c) a power supply associated with the case; (d) a microprocessor associated with the case, the microprocessor being powered by the power supply; (e) an electronic sensor powered by the power supply and monitored by the microprocessor, and adapted to detect the presence or absence of a card in the card receptacle; and (f) an alarm which is activated when a card is not returned to its card receptacle, and the case is closed.

Abstract: A road surface friction detector for use in a vehicle. The detector provides information regarding the integrity of a road surface to an operator of the vehicle. The detector is made up of three main parts, a sensor unit, a display unit and a microprocessor unit. The sensor unit is made up of a first sensor unit and a second sensor unit. The first sensor unit contains a first light source which directs light at the road surface to be reflected back to a first light receiver. The amount of light that returns to the first light receiver corresponds to various conditions on the road. The second sensor unit is made up of a second light source, second light receiver and a reflective element. The second light source directs light at the reflective element which is located between the second light source and the road. The light from the second light source is then reflected off of the reflective element to the second light receiver.

Abstract: An improved fire detector is obtained by combining a conventional smoke particle sensor with a fire radicals odor sensor; the latter being an electronic nose tuned to respond to the presence of a family of radicals, produced by most fires, that is responsible for the odor associated with a fire. The conventional smoke particle sensor is prevented from producing an alarm signal unless the tuned electronic nose senses that the fire-produced radicals are increasing at a rate that exceeds a preset threshold rate. In another aspect of the invention, the smoke particle sensor is provided with a second, lower, threshold connected to a timer so that an alarm will be produced if the lower threshold is exceeded, without interruption, for a preset time. The improved fire detector, using the combined sensors, has greater sensitivity and a lower false alarm rate.

Abstract: To monitor a patient, an alligator clip is fastened to the patient by a cord having a length of between five inches and five feet. The other end of the cord is connected to a switch which is activated when the patient moves beyond the length of the cord to cause a message to be announced. A pressure pad is located under the patient and armed by the application of weight to the pad. Upon removal of the weight the alarm is given.

Abstract: A pool alarm system including a programmable control circuit, a control keypad, a number of planar focused infrared motion detectors, a key alarm system activation switch, an audible alarm output system, a drain blockage sensor, and a pool pump motor control relay. The drain blockage sensor is installed in place of the existing drain cover and includes a perforated dome shaped cover member slidably mounted to a compression detector including a spring biased plunger slidably mounted within a plunger cylinder. The spring biased plunger has a permanent magnet secured to a plunger bottom surface thereof. The plunger cylinder has a magnetically actuated reed switch in electrical connection with a drain stoppage input of the programmable control circuit and positioned on a bottom cylinder surface thereof. Each of the number of planar focused infrared motion detectors has an infrared sensing area having a planar bottom to allow for sensing motion at or a near a pool water surface.

Abstract: The present invention provides a monitoring system (30) for monitoring operation of dynamic plant apparatus (10, 100). Electronic processing means (31, 32, 33) is provided for processing the electrical parameter signals provided by sensors (11-15) and is capable of thereby producing a plurality of different fault signals. Display means (34) is provided for displaying fault information to a user of the monitoring system (30), the display means (34) being controlled by the fault signals produced by the electronic processing means (31, 32, 33). The electronic processing means (31, 32, 33) compares the values of at least some of the measured parameter signals with limit values stored in memory by the electronic processing means (31, 32, 33) and when the comparison shows that the value of a measured parameter signal is outside the respective limit value the electronic processing means (31, 32, 33) produces a respective basic fault token signal.

Abstract: A system is disclosed for indicating the status of a person occupying a cubicle, office or other enclosed space by means of automatically or manually initiated visual or audio-visual signals, particularly relating to the occupant's presence, the relative length of absences, the wish to work without being disturbed, and the need for emergency assistance. The system is controlled by a control unit with a micro-controller, a communications link, a red button, an amber button and a green button, each having a lamp of the corresponding color. A motion detector is connected to the control unit for detecting the presence or absence of motion in the monitored space. A proximity detector is connected to the control unit for detecting the passage of a person through the doorway of the monitored space. Also connected to the control unit is an indicator unit with a beeper and red, amber and green lamps functioning in tandem with the lamps of the control unit.

Abstract: A monitoring apparatus and method are provided for a communication system in which a central office communicates to at least one end unit using intermediate remote nodes. The remote node receives signals from both the central office and the end units. Each remote node can be equipped with apparatus for monitoring the integrity of paths of the communication system. The monitoring apparatus can include a mixing device that mixes received signals to produce combined signals. The received signals generally include a pilot signal sent from the central office and a data signal sent from the at least one end unit. The state of the communication system is analyzed based on the combined signals. If the combined signals includes only the data signal from the end unit, the path through which the pilot signal was sent is inoperative. If the combined signals includes only the pilot signal, the transmission path from the end unit over which the data signal is sent is inoperative.

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: Protective mask communication systems are provided for use in hazardous environments, e.g., firefighting and hazardous waste clean-up operations. The systems allow wearers of protective masks working in a hazardous area to readily communicate both with each other and with personnel and automated systems outside of the area. Preferred systems provide short range radio communication between mask wearers.

Abstract: A combination smoke detector and severe weather warning device is housed in a common housing, such as a housing resembling that for a conventional smoke detector. The combination device includes a smoke detector and alarm for sensing smoke and/or fire in the immediate area and transmitting an audible alarm, and also includes a VHF FM radio for receiving severe weather broadcasts and alerts from the National Oceanic And Atmospheric Administration (NOAA), from a remotely located transmitter. Preferably different audible alarms are provided for the smoke detector and for severe weather warnings from the radio, in order that persons may distinguish the type of alarm issued by the device. The combination device is preferably powered by an electrical power supply installed within the building structure within which the device is installed, but may be powered by self contained electrical batteries.

Abstract: A portable intruder detection system for campsites notifies unsuspecting campers of campsite intrusions by two legged or four legged intruders. The system comprises a 360 degree motion sensor and a hardwired or RF remote arm/disarm and notification system. A plurality of infrared motion detection modules are included, each module being provided with a lightweight support, a solar panel battery charging device, and an alarm signal. The alarm signal includes flashing lights and/or an audible signal such as a siren or a simulated natural bird sound. A remote control unit communicates with the modules by either hardwired connections or radio frequency signals. The remote control unit enables the camper to monitor and control the alarm modules.

Abstract: A device monitors the distance between one or more golf clubs having a first transceiver attached thereto and a second transceiver which may be associated with or attached to a golf bag, a golf cart, or the clothing of a golfer. When a golf club is separated from the second transceiver by more than a predetermined threshold distance, an alarm is actuated, warning the golfer that a golf club previously removed from the bag has not been returned. The risk of loss or theft of the golf clubs is thereby substantially reduced.

Abstract: A set of sensors or sensor pairs capable of detecting the presence of a person passing through a portal is used for monitoring the portal. In one embodiment the portal has spaced apart upright supports. On one of the upright supports is mounted the sensors and the other upright support is used as a surface for reflection of the wave energy transmitted. When a person is present in the portal the person reflects the wave energy. The receiver is capable of detecting the time duration between transmission and receipt of the wave energy signal. In a second embodiment, the sensors are mutually inductively coupled in pairs. When a person is present within the portal the mutual inductance is changed in one or more of the sensor pairs. This change in mutual inductance is sensed and used as a means for determining which person is present in the portal. For example, a family may comprise two adults, a teenager, a preteen and a small child.

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.