Abstract: Systems and methods in accordance with various embodiments of the invention can be utilized to implement unmanned aerial vehicles (“UAVs”) designed for autonomous operation in cluttered environments, indoor environments and/or as photography drones. One embodiment includes: launching an unmanned aerial vehicle (UAV); performing in flight path planning to scan an area for people using the UAV; detecting the presence of at least one subject by processing image data captured by at least one camera on the UAV; determining at least one pose from which to capture images of detected at least one subject using the UAV; performing path planning to navigate the UAV to the determined at least one pose; and capturing images of the detected at least one subject using at least one camera on the UAV when the UAV is posed in one of the determined at least one pose.

Abstract: In a general aspect, a filter time aligns time varying RF-motion data. In some aspects, a method includes loading a first set of input signals (SISs) into an interference buffer over a first time period. The first SISs is based on a first set of wireless signals received by a wireless communication device (WCD) after being transmitted through a space. The method includes using the first SISs to determine an interference level. The method includes: in response to determining the interference level is below a threshold, executing a motion detection process in a second, subsequent time period over which a second SISs is loaded into the interference buffer. The motion detection process, using a subset of the first SISs, detects motion of an object in the space. The second SISs are based on a second set of wireless signals received by the WCD after being transmitted through the space.

Abstract: An active-pulsed four-dimensional camera system that utilizes a precisely-controlled light source produces spatial information and human-viewed or computer-analyzed images. The acquisition of four-dimensional optical information is performed at a sufficient rate to provide accurate image and spatial information for in-motion applications where the camera is in motion and/or objects being imaged, detected and classified are in motion. Embodiments allow for the reduction or removal of image-blocking conditions like fog, snow, rain, sleet and dust from the processed images. Embodiments provide for operation in daytime or nighttime conditions and can be utilized for day or night full-motion video capture with features like shadow removal. Multi-angle image analysis is taught as a method for classifying and identifying objects and surface features based on their optical reflective characteristics.

Abstract: A wetness sensor includes a self-supporting substrate and an electrically conductive trace carried by the substrate. The trace is patterned to provide at least a portion of a tuned RF circuit, which may be disposed on only one side of the substrate and characterized by an impedance or resistance. The trace is not self-supporting. The substrate is adapted to dissolve, swell, or otherwise degrade when contacted by a target fluid. Such degradation produces a drastic change in the operation of the RF circuit, which can be interpreted by a remote reader as a “wet” condition. Contact of the substrate by the target fluid may change the impedance or resistance of the RF circuit by at least a factor of 5, 10, 100, or 1000, and/or may cause the trace to disintegrate so as to provide the RF circuit with an open circuit, and/or may substantially render the RF circuit inoperative.

Abstract: In some aspects, a radio-frequency (RF) camera system includes a sensor assembly and a data processing system. The sensor assembly includes sensors supported at respective sensor locations. Each sensor is supported at one of the sensor locations and configured to detect RF signals from a field of view defined by the sensor assembly. Each sensor is configured to identify parameters of the RF signals detected by the sensor. The data processing system is configured to receive the parameters identified by the sensors and generate a graphical representation of the field of view based on the parameters.

Abstract: A method and apparatus are provided, wherein the apparatus performs the steps of detecting a moving object within a secured area, determining a size of the moving object, determining that the size exceeds a predetermined size threshold value associated with an animal, determining an aspect ratio of the moving object, determining that the aspect ratio meets a predetermined aspect ratio threshold value associated with an animal or crawling human, but not an upright human, retrieving an indicator from memory that establishes whether an animal is present or not present within the secured area, and setting an alarm upon detecting that the moving object exceeds the predetermined size threshold value, that the determined aspect ratio meets the predetermined aspect ratio threshold value of an animal or crawling human, and that the indicator establishes that there is no animal present in the secured area.

Abstract: A method for automated detection of illegal substances smuggled inside internal cavities of a passenger, e.g., as capsules. The method provides for an automated detection of narcotics hidden in a passenger's stomach area using pictures produced by an X-ray scanner. According to an exemplary embodiment, throughput of the scanner is increased by an automated detection algorithm, which takes less time than visual analysis by an operator. The operator is only involved in cases when narcotics are detected. The automated detection method has a consistent precision, because the effects of tiredness of the operator are eliminated. Efficiency and costs of the process are improved, since fewer qualified operators can service several scanners.

Abstract: A system of altering an audio signal presented to a user may include an input configured to receive data indicating a status of an environment outside of an audio device, where the audio device is configured to present an audio signal to a user. The system may also include a detection unit configured to detect a condition based on the received data and an audio altering unit configured to direct altering of the audio signal presented to the user based on the detection of the condition.

Abstract: For monitoring an area, signal strength samples are obtained (S1) by sampling a data signal transmitted from at least one first device and received by at least one second device, and measuring a signal strength of the sampled data signal. The signal strength samples are processed (S2) by forming consecutive first groups of N consecutive signal strength samples, calculating first standard deviations for each of the consecutive first groups, forming consecutive second groups of N consecutive first standard deviations, and calculating second standard deviations for each of the consecutive second groups. Based on the second standard deviations, it is detected (S3) if a fluctuation in the data signal received by the second device has occurred that represents an intrusion in the area.

Abstract: A method for remotely sensing cardiac-related data of an animal subject includes transmitting a RF signal to impinge on tissue of the subject, receiving a reflected portion of the RF signal, generating baseband data, filtering baseband data (e.g., including high pass filtering), performing waveform phase position determination, performing at least one auto-correlation of the waveform phase position determined data, determining periodicity of the auto-correlated data, and (i) computing heart rate using a maximum periodicity of the periodicity, or (ii) identifying abnormalities in cardiac function, such as may be indicated by temporal variations in heart rate and/or signal amplitude corresponding to cardiac activity. Multiple bandpass filtering schemes may be employed.

Abstract: An intrusion detecting device includes a transmitter configured to transmit ultrasonic waves, a receiver configured to receive ultrasonic waves, and a controller configured to control the transmitter to output ultrasonic waves with a reference period, and configured to control a transmission period of the transmitter such that a voltage level of received ultrasonic waves may become equal to a reference voltage level. The controller is configured to determine an intrusion based on the voltage level of the received ultrasonic waves and a frequency of the received ultrasonic waves.

Abstract: A system for providing locality information to a user is disclosed. The system comprises at least one magnetic field beacon. Each beacon comprises means for generating a magnetic field encoded with information associated with the beacon. A communication device is provided that comprises means for detecting the encoded magnetic field emitted by the beacon and means for extracting the information encoded in the detected magnetic field.

Abstract: Systems, methods, and devices for deploying a network of nodes in an area of interest are described herein. For example, in one or more embodiments, the area of interest can be determined, a bounding box can be created for the area of interest, the bounding box can be filled with a node deployment grid, a determination of whether a node in the node deployment grid is an essential node or an enhancement node can be made, the enhancement node can be removed when it provides duplicate coverage to each portion of the area of interest that is provided coverage by the enhancement node, at least one of the essential node and the enhancement node can be connected to a node in the node deployment grid when they are disconnected from nodes in the node deployment grid with a minimum spanning tree.

Abstract: Disclosed are a method for measuring a acoustic transfer function of a predetermined space to be secured or monitored through a correlation between sound signals acquired from a sound source generating device and a sound measuring device and a method and a system for judging whether there is an intrusion object by using a difference between an initially set acoustic transfer function information and varied acoustic transfer function information by using the method for measuring the transfer function. In the present disclosure, when an object moves or an intrusion object is generated in a predetermined space, intrusion or no intrusion is monitored by variation of the acoustic transfer function varied by the intrusion object even though there is no noise generated by the intrusion object.

Abstract: A real-time threat detection system incorporating a plurality of sensors adapted to detect radiation across the majority of the electromagnetic spectrum. The system also includes an aided or automatic target recognition module which compares the data from the sensors against known radiation signatures and issues an alert when an anomalous signature is detected. The system further includes an operator station which displays sensor information allowing the operator to intervene. The sensors detect radiation which is normally emitted by persons or other bodies and display areas to the operator where normal emissions are blocked.

Abstract: An ultrasonic occupancy sensor for detecting presence or absence of an occupant in a space includes an ultrasonic receiving circuit having a synchronous rectifier that allows the circuit to detect small-magnitude ultrasonic waves having a Doppler shift. The sensor comprises an ultrasonic transmitter for transmitting ultrasonic waves at an ultrasonic operating frequency, and a controller that drives the transmitting circuit with complementary drive signals to control the ultrasonic operating frequency. The synchronous rectifier receives the drive signals from the controller and rectifies an amplified input signal to generate a rectified signal, which is filtered by a filter to generate a filtered signal. The controller receives the filtered signal and determines that the space is occupied if the magnitude of the filtered signal exceeds a threshold.

Abstract: A refrigerator includes a refrigerator cabinet and a refrigerating compartment within the refrigerator cabinet. A beverage dispensing system is operatively connected to the refrigerator cabinet, the beverage dispensing system configured to dispense a stream of a beverage. The beverage dispensing system includes a light source and a light sensor positioned on opposite sides of the stream of the beverage. The beverage dispensing system is configured for detecting if dispensement of the beverage is occurring and characterizing the volume or amount of the beverage being dispensed.

Abstract: A method and system are described for estimating an environment surrounding a wireless communication system, the environment including at least one inflector that inflects transmitted signals. An observation generator receives an input signal transmitted from a transmitter to a receiver via a wireless communication channel and also receives system state information pertaining to at least one of the receiver, the transmitter and the inflector. An observation processor uses observations from the observation generator to estimate at least one property of the inflector based on the received input signal and the system state information.

Abstract: An improved alarm system for monitoring movement through a passageway defined by opposing sidewalls comprises a lower passage indicator disposed toward the lower ends of the sidewalls, an upper passage indicator disposed toward the upper ends of the sidewalls and a control mechanism configured to sound an alarm if one of the passage indicators indicates passage through the passageway and the other passage indicator does not. In a preferred embodiment, the alarm system is configured as a pool alarm and each passage indicator comprises an emitter/receiver that emits an infrared beam toward an opposing reflector to provide a lower beam and an upper beam. If only the lower beam is interrupted, indicating a child passing through the passageway, the control mechanism will generate an alarm signal. If both beams are interrupted, indicating an adult passing through the passageway, the control mechanism will not generate the alarm signal.

Abstract: An array of paired V-band sensors is provided to act as a virtual fence to detect human intrusion. Each sensor includes a rotating circuit board that includes an antenna array. The sensor pivots the circuit board with regard to a weight base to align with an opposing sensor. By alternatively transmitting and receiving with regard to the opposing sensor, a V-band bistatic radar system is enabled that detects human intrusion between the opposing sensors.

Abstract: A method and a system evaluate a security situation in a building. The building has accommodation areas with access authorization for authorized persons. A count of the persons present in the accommodation areas is determined in that, in a radio network which contains a plurality of radio stations arranged spatially distributed in the ceiling, wall or floor, the influencing of the radio field of the radio stations between one another by persons physically present there is evaluated, by a radio tomographic location and detection method. A current count of identifiers which are read by RFID reading devices of RFID transponders is determined, the identifiers being carried by authorized persons. The RFID reading devices are arranged there spatially distributed in the ceiling, wall or floor. Based on the respective counts of personal identifiers and the determined person count, an indicator for evaluating the current security situation in the building is determined.

Abstract: An apparatus is disclosed including one or more security structures. The one or more security structures includes: a weldable frame; a plurality of composite panels, each panel securable to the weldable frame, each composite panel configured to form at least one joint with at least one adjoining composite panel; and a respective security element embedded within each of the composite panels. The security element is configured to detect a breach in the composite panel.

Abstract: An intrusion detector comprises a housing including a cover and baseplate mounting a circuit board. The cover and baseplate are removably mountable to a base. A motion sensor and bracket are mounted to the circuit board. The cover has a lower lookdown window. A lookdown enable/disable actuator extends from a rear side of the circuit board and is accessible through the baseplate. The actuator is operable to move a door pivotally mounted to the bracket between an on position to enable a lookdown function and an off position to disable the lookdown function. The detector is normally mounted on a wall by securing the base to the wall. The cover and baseplate can be removed from the base. A screwdriver can be used to turn the actuator. The cover and baseplate can then be remounted to the base.

Abstract: A system is disclosed for controlling operation of an electronic device, such as a TV. The system includes a first sensor located at or near the electronic device and a second sensor spaced apart from the first sensor, wherein the first and second sensors are configured to detect motion of a user within an operating zone associated with the electronic device. A processor is coupled to the electronic device and the first and second sensors, the processor being configured to input a signal from the first and second sensors. Memory is coupled to the processor, the memory comprising a sensing algorithm configured to process the input signal from the first and second sensors and determine the location of the user with respect to the operating zone. The processor is configured to send a control command to the electronic device based on an output of the sensing algorithm.

Abstract: An occupancy detection network controls illumination from lighting devices in each of a plurality of defined areas. Motion detection modules and sound detection modules provide output signals based on detected occupancy in each defined area. The sound detection modules automatically adjust sorting criteria over time in accordance with identified sound characteristics associated with occupancy, detect sound in the associated defined area in accordance with the sorting criteria, and provide an output signal based on the detected sound. A central lighting controller is linked to the detection modules via a common bidirectional data bus. The controller receives an output signal, determines an occupancy state for the associated defined area, and controls lighting devices in the area to be turned on and off in accordance with the determined occupancy state.

Abstract: A mobile object detecting apparatus includes first radiation detecting means; and second radiation detecting means for radiating an electromagnetic wave having the same frequency as the electromagnetic wave radiated by the first radiation detecting means such that the radiated electromagnetic wave passes near a point in the first radiation detecting means from which the electromagnetic wave is radiated, and detecting a standing wave which is generated due to reflection of the radiated electromagnetic wave at an object; wherein a distance, over which the electromagnetic wave radiated by the first radiation detecting means travels until it reaches near the first radiation detecting means, corresponds to a distance of an integral multiple of a wave length of a half cycle of the electromagnetic waves radiated by the radiation detecting means plus a wave length of a predetermined period which is smaller than the half cycle.

Abstract: The status of a device is controlled by detecting (403) the presence of a user; changing the status of a device to a first state (405) if the presence of a user is detected within a first, predetermined zone; changing the status of the device to the second state (407) if the presence of a user is detected outside a second, predetermined zone, the first, predetermined zone being smaller than and being wholly contained within the second, predetermined zone; and maintaining (407) the current state of the device if the presence of a user is detected outside of the first, predetermined zone and within the second predetermined zone.

Abstract: A method and apparatus of recognizing the presence of a passenger in front of a door of a transit vehicle comprises directing an ultrasound transmitter/receiver at a volume of space adjacent the door, emitting an ultrasound pulse into the empty volume, recording and integrating intensity of the echoes and storing the integrated value as a standard value, repeatedly emitting an ultrasound pulse into the volume, and comparing the integrated values to the standard value.

Abstract: Disclosed is a proximity switch provided with an actuator unit and a sensor unit. The sensor unit is provided with an antenna coil, a transmitting circuit which transmits electromagnetic waves at a constant frequency to the antenna coil, a receiving circuit which detects external signals received by means of the antenna coil, and control circuits. The actuator unit is provided with an antenna coil, a power supply circuit which rectifies an electromotive force generated in the antenna coil, and a signal processing circuit which receives power supply from the power supply circuit, performs frequency-dividing to the signals received by means of the antenna coil, and transmits the signals from the antenna coil after the frequency-dividing. The control circuit of the sensor unit has memory for registering the frequency of the signals transmitted from the actuator unit.

Abstract: An intrusion detection and tracking system includes a plurality of nodes, a DP and a gateway. The nodes are disposed about an area and form a wireless network to be monitored, the nodes are configured to receive data and transmit data frames with a signal strength indicator and/or a link quality indicator in the frames. The DP is communicatively connected to the network and configured to analyze variations in the signal strength indicator and/or link quality indicator to detect and track disturbances to an electromagnetic field in the area. The gateway is configured to form a data link between the network and the DP.

Abstract: The invention relates to a method, a device and a system for preventing false alarms in a theft-preventing system comprising a magnetic field for detecting at least one metal object in a first detection zone and means for determining a time-difference; said method comprising the steps of detecting a first change in a parameter indicative of the magnetic field in said first detection zone; detecting a second change in the parameter indicative of the magnetic field in said first detection zone; determining a time-difference between the detection of said first change in said parameter and the detection of said second change in said parameter; and performing an action based on said time-difference. In this way, false alarms due to a metal detector falsely detecting for example movement of metal-doors in a first detection zone may be reduced/eliminated. Additionally, the false alarms due to an opening and/or closing of a door with metal parts acting as an active tag may be reduced/eliminated.

Abstract: A device (1) for preventing and detecting the falling of an object or of a person on a line (2) of a railway station having a platform (3). The device (1) includes at least one detection device (7) having at least one emitter (8) of a beam (10) and a sensor (9) able to detect the beam (10), and a detection calculator (13) for processing the signals obtained from the sensors (9) and able to communicate safely with at least one signaling system (16a, 16b, 16c) of the railway station, barriers (4) able to be arranged on the platform (3) to prevent falls of the object or of the person, the barriers (4) delimiting between door opening areas (5), a detection device (7) being arranged in each of the door opening areas (5) to detect a fall on the line (2) of the railway station.

Abstract: A system and methods for building a map non-invasively (i.e. mapping of occluded and non-occluded obstacles) based on a small number of wireless channel measurements. Approaches for building an obstacle map are based on coordinated space, random space and frequency sampling, such that the sparse representation of the map in space, wavelet or spatial variations, are exploited in order to build the map with minimal sensing.

Abstract: Embodiments described herein relate to an apparatus for attaching elements of a magnetic field safety system to headwear worn by a worker. In various embodiments, the headwear includes a combination of a sounder device, light assembly, personal alarm device and power source.

Abstract: A technique for operating a Radio Frequency Identification, RFID, reader with motion detection includes detecting a motion in proximity to the RFID reader, and triggering the RFID reader to read any tags in proximity to the RFID reader in response to detecting a motion in proximity to the RFID reader. Detecting a motion can also generate a change in digital signage, or communicate information about read tags to a local area network. Operating this system only when motion is detected saves battery life.

Abstract: A real-time threat detection system incorporating a plurality of sensors adapted to detect radiation across the majority of the electromagnetic spectrum. The system also includes an aided or automatic target recognition module which compares the data from the sensors against known radiation signatures and issues an alert when an anomalous signature is detected. The system further includes an operator station which displays sensor information allowing the operator to intervene. The sensors detect radiation which is normally emitted by persons or other bodies and display areas to the operator where normal emissions are blocked.

Abstract: A proximity sensor can be used with a device that relies on GPS signals or other radio-frequency (RF) signals. The proximity sensor can be used to determine if the signals are being deliberately blocked by an object such as metal foil placed near it. The sensor includes an oscillator 2, a directional coupler 4 and an antenna 8. A third port 6c of the directional coupler acts as a coupled port when RF power that has been transmitted by the antenna 8 is reflected back to the antenna by a blocking object. The reflected RF power passes along a main line of the directional coupler 4 and a proportion is coupled to the third port 6c. A detector provides an alert if the magnitude of the power of the transmit signal that is reflected back to the antenna 8 in the form of a receive signal exceeds a threshold.

Abstract: A system is disclosed for controlling operation of an electronic device, such as a TV. The system includes a first sensor located at or near the electronic device and a second sensor spaced apart from the first sensor, wherein the first and second sensors are configured to detect motion of a user within an operating zone associated with the electronic device. A processor is coupled to the electronic device and the first and second sensors, the processor being configured to input a signal from the first and second sensors. Memory is coupled to the processor, the memory comprising a sensing algorithm configured to process the input signal from the first and second sensors and determine the location of the user with respect to the operating zone. The processor is configured to send a control command to the electronic device based on an output of the sensing algorithm.

Abstract: In an intruder identifying method and device, an intruder identifying sensor device identifies an intruder as a detection target to be originally detected by determining whether a variation style for a predetermined time of intruder intrusion state information based on the reception signal of the electric wave receiving unit during a time period from the time when the intruder identifying sensor device detects an intruder till the time when the intruder identifying sensor device does not detect the intruder is a predetermined variation style.

Abstract: A method and system for testing and calibrating an accelerometer of an electronic device are provided. In accordance with one embodiment, there is a method of testing and calibrating an accelerometer of an electronic device, comprising: detecting the electronic device within a nest of a test fixture; calculating an offset value for each sensing axis of the accelerometer in response to detecting the electronic device within the nest; and storing the offset values in a memory of the electronic device.

Abstract: System (10) for detecting the position of a mobile or immobile entity (20) in a defined space (30), characterized in that it includes: means (40) of detecting the presence of said entity in at least two partially overlapping observation areas (Z1, Z2) of said space, said means being adapted for collecting at least one piece of immobile presence information (Ip) and one piece of movement information (Im) of said entity in each of said observation areas, processing means (50) which are adapted for carrying out logic operations on at least a portion of said information collected for each of said observation areas, decision means (60), which are connected to the processing means and adapted for controlling an action on the basis of a logic signal generated by the processing means.

Abstract: The invention relates to an access control device (1) having at least one access barrier element, to which at least one read unit and/or sensor unit for acquiring legitimation and/or security features is assigned, the access barrier elements and the read and sensor units each having a data connection to a computer unit (5), which compares the acquired or read features to stored data and opens or keeps closed the access barrier according to a preset. Proceeding from the problem that in the case of access control devices (1) of this type, it is only possible to react to changed requirements or a changed security condition by cumbersome re-parameterization of the facility, an additional operating element (8), which is assigned to the computer unit (5), is proposed in the context of the invention, using which it is possible to select between various security steps by simply adjusting the operating element (8).

Abstract: For one setting operator being able to readily adjust a threshold by oneself, by means of reporting units that issue a report to indicate the amount of variation in a received electric wave when an intruding object has intruded between a transmitting leaking transmission path and a receiving leaking transmission path, and a remote controller that generates a signal which changes a threshold in the table through the receiving leaking transmission path, the threshold is adjusted properly for each of the blocks with the remote controller based on the report issued from the reporting unit to indicate the amount of variation in the received electric wave caused by a trial intrusion between the two transmission paths by a threshold setting operator.

Abstract: A method and apparatus are provided for automatically testing microwave instruction detection modules of a security system. The method includes the steps of detecting intruders within a protected space by monitoring a Doppler output of a signal extraction circuit coupled to a microwave transceiver module, varying a frequency of direct current power pulses applied to the microwave transceiver module, detecting a difference in magnitude of the Doppler output of the signal extraction circuit over the varied frequency and comparing the detected difference with a fault threshold level.

Abstract: An intrusion detection system that provides foliage penetration is disclosed employing an array of field disturbance transceivers operating at UHF frequencies. The array of transceivers generate a multiplicity of electromagnetic wave fields between nearby units and detect the presence of intruders by detecting disturbances in these fields. The emitted UHF signals used to generate the electromagnetic wave fields are also used to provide the communication link between transceivers in the array and to a control station. The control station facilitates the operation of the array from a remote monitoring site. A unique method of array deployment provides multiple opportunities to detect an intruder and secondarily provides redundant communication links in case of a sensor failure. Automatic means of setting detection thresholds based on environmental conditions assures a high probability of detection along with a low false alarm rate.

Abstract: A presence detection system for detecting objects which move through an entrance of a space. The system is based on the idea to create a signature of a moving object which can be used to determine whether the object is a human being.

Abstract: A dosimeter is disclosed for use in container including outer walls defining an interior volume, the dosimeter including: a radon detection element adapted to detect a radon level for the interior volume; a neutron detection element adapted detect a neutron level for the interior volume. The dosimeter is adapted to measure the radon level and neutron level for a period of time, compare the measured radon level to a first threshold, compare the measured neutron level to a second threshold, and determine information indicative of the presence or absence of fissile material within the interior volume based on the comparisons.

Abstract: A lighting controller may optimize a timeout value of a lamp based on the goals of saving energy and providing occupant comfort. The lamp may illuminate a lighting area. The lighting controller may determine a false-negative rate for the lamp from sensor data that represents a frequency at which the lamp is timed out while the lighting area is occupied. The lighting controller may adjust the timeout value of the lamp over time so that the false-negative rate approaches a threshold false-negative rate. The false-negatives and occupancy periods may be detected from spikes in time distributions of motion data. The amount of energy that the lamp would consume at an increased timeout value of the lamp may be determined from motion data stored while the timeout value of the lamp is at an initial timeout value.

Abstract: A motion detector system includes the ability to detect motion through the use of a Doppler radar sensor or a combination of PIR sensors and a Doppler radar sensor. The system includes an outdoor light fixture having one or more lamps and a housing coupled to the outdoor light fixture. The housing includes a Doppler radar sensor and a microprocessor for analyzing the signals received by the Doppler radar sensor. Alternatively, the housing includes a combination of PIR sensors and a Doppler radar sensor and a microprocessor for analyzing the signals received from these sensors. The lamps in the light fixture are activated when either the PIR sensor or the Doppler radar sensor generates a signal indicating motion within the monitored area. Alternatively, the lamps can be activated when either the PIR sensor or the Doppler radar sensor senses predetermined number of motion activities over a limited time period.

Abstract: An ultrasonic occupancy sensor for detecting presence or absence of an occupant in a space includes an ultrasonic receiving circuit having a synchronous rectifier that allows the circuit to detect small-magnitude ultrasonic waves having a Doppler shift. The sensor comprises an ultrasonic transmitter for transmitting ultrasonic waves at an ultrasonic operating frequency, and a controller that drives the transmitting circuit with complementary drive signals to control the ultrasonic operating frequency. The synchronous rectifier receives the drive signals from the controller and rectifies an amplified input signal to generate a rectified signal, which is filtered by a filter to generate a filtered signal. The controller receives the filtered signal and determines that the space is occupied if the magnitude of the filtered signal exceeds a threshold.