Abstract: Beams are irradiated in three directions by switching an irradiation direction of a mainlobe of an antenna by stages, and an echo is received from a detection object obtained in the mainlobe or a sidelobe in each irradiation direction. Then, reflection power intensity in each irradiation direction is found from the received echo, and pattern of relative variation of the reflection power intensity (power intensity pattern) in each irradiation direction is generated. Meanwhile, a detection region is divided into seven bearings “c” to “i” and a power intensity pattern when an object exists in each bearing is previously stored as a reference pattern in each bearing. Then, the bearing in which the detection object exists is specified by comparing the power intensity pattern obtained from the received echo with the reference pattern in each bearing.

Abstract: A plurality of primary detection regions A to I are scanned by switching a beam width and a beam direction of an antenna. The primary detection regions A to I are formed such that one detection region overlaps at least one of other detection regions. A small region (any one of secondary detection region (1) to (14)) corresponding to a region provided by excluding a region corresponding to a sum of set of the detection regions where a detection object was not detected, from a region corresponding to a product set of the primary detection regions where the object was detected is specified as a bearing in which the object exists, based on detection results of the respective primary detection regions.

Abstract: Targets imaged by radar systems typically have shadows associated with them. Target detection and identification is enhanced by analyzing the shadow characteristics of a suspected target. Features of the shadow cast by the suspected target enhance the identification process. Authenticating the suspected target shadow as being indeed cast by the target comprises a) Generating a radar image using radar returns, the radar image containing both the target and its suspected target shadow; b) Forming a pentagonal perimeter adjacent to the target (within the radar image), the pentagonal perimeter chosen to contain the suspected target shadow, the pentagonal perimeter separating the target from its suspected target shadow; c) Testing the suspected target shadow within said pentagonal perimeter to authenticate that the suspected target shadow is cast by the target. One aspect of the testing performed on the suspect target shadow uses a 2 by 2 dilation and majority filter.

Abstract: A planar microstrip microwave transceiver employing a chip on board design where all components can be surface mounted. The transceiver employs a surface mounted FET chip in a low Q oscillator and a pair of surface mounted Schottky chips in balanced mixer, all of which are wire bonded to microstrip circuitry.

Abstract: A microwave sensor is described, with a self-mixing oscillator (1), with a transmitting and receiving antenna (2), with an impedance (3) which is connected between the current or voltage supply (4) and the oscillator (2), and with an evaluation circuit (5), the self-mixing oscillator (2) producing both the transmitted signal and also mixing the transmitted signal with the received signal and the low-frequency mixed (Doppler signal) being tapped on the impedance (3) and supplied to the evaluation circuit (5).

Abstract: A system and method for highly selective intrusion detection using a sparse array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array around the perimeter of a building. Each TM-UWB radar transmits ultra wideband pulses that illuminate the building and the surrounding area. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the inside of the building and the surrounding area. This image is used to detect motion in a highly selective manner and to track moving objects within the building and the surrounding area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.

Abstract: A mobile surveillance vehicle security system, comprising one or more low profile vehicles equipped with a combination of thermal and radar equipment to provide surveillance of large areas using few assets, extended line-of-sight surveillance, integration with other sensor systems, information sharing, and system survivability of loss of sensors and vehicles.

Abstract: The present motion detector unit effectively suppresses harmonic frequencies and is cost-effective to build. The motion detector unit includes a main casing which houses the main microwave circuit board (3). Enclosing the casing and the circuit board (3) is a cover. An antenna circuit board is attached to the bottom side of the main casing. The cover has partitioning walls at the bottom side of the cover which press against the main microwave circuit board (3) when the cover is enclosed over the casing. The circuit on the main microwave circuit board (3) includes a microwave oscillator for producing an oscillatory signal. The oscillator is coupled to a ground and to a filter which is a low-pass filter with a relatively wide stop bandwidth. The filter is then coupled to a transmitting antenna. A power supply is routed through the transmission antenna and provides DC voltage to the microwave oscillator. The oscillator is further coupled to a mixer.

Abstract: A communication system using a leakage transmission path, for sending and receiving signals lying within a passband, which the leakage transmission path essentially has as a conductive line, is provided with a signal generation unit for generating a signal to be transmitted by way of the leakage transmission path, and a relay unit disposed on a way of the leakage transmission path, for relaying the signal from the generation unit, and for converting the signal applied, via a cable, thereto into a signal lying within the passband, which the leakage transmission path essentially has, so as to send out it.

Abstract: A compact, autonomous motion detecting and alerting system alerts to the movement of objects of interest. Mounted on an environmentally sealed PC board are a transceiver such as a CW radar front-end, connectors, signal processors and a communications device. The system provides early warning of movement of an ice sheet or rubble field via the communication device that may be a cellular telephone. This system is mounted proximate the target surface under observation, oriented at pre-specified offset angles both laterally and in elevation. The target is illuminated and energy reflected therefrom is mixed with a portion of the transmitted signal to produce a difference frequency signal that is processed to establish existence of motion within a pre-specified velocity range. Upon verification of motion, notification is sent to a responsible authority. An autonomous or semi-autonomous power source and integral power management function may be incorporated on the same PC board.

Abstract: A system and method for highly selective intrusion detection using a sparse array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array around the perimeter of a building. Each TM-UWB radar transmits ultra wideband pulses that illuminate the building and the surrounding area. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the inside of the building and the surrounding area. This image is used to detect motion in a highly selective manner and to track moving objects within the building and the surrounding area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.

Abstract: An intrusion detection system and method are provided that can utilize impulse radio technology to detect when an intruder has entered a protection zone. In addition, the intrusion detection system and method can utilize impulse radio technology to determine a location of the intruder within the protection zone and also track the movement of the intruder within the protection zone. Moreover, the intrusion detection system and method can utilize impulse radio technology to create a specially shaped protection zone before trying to detect when and where the intruder has penetrated and moved within the protection zone.

Abstract: A radar detection process includes computing a derivative of an FFT output signal to detect an object within a specified detection zone. In one embodiment, a zero crossing in the second derivative of the FFT output signal indicates the presence of an object. The range of the object is determined as a function of the frequency at which the zero crossing occurs. Also described is a detection table containing indicators of the presence or absence of an object within a respective radar beam and processing cycle. At least two such indicators are combined in order to detect the presence of an object within the detection zone and with changing range gates in each of the antenna beams the coverage of the detection zone can be varied.

Abstract: A sensitive display system is described. The sensitive display system allows for mediation of content provided from a source to a recipient, such as from a web server to a web browser. Mediation may involve intercepting and augmenting the content so as to restrict or otherwise control information displayed on a display of the recipient device. In this way, the sensitive display system allows restricted information to be replaced with security status messages, or removed entirely. For example, when a user comes within a specified distance from the sensitive display area, a security classification level of the approaching user is used to determine whether there should be any change in the display. If so, a mediating device causes a browser push to occur, to thereby block or otherwise restrict some or all of the display.

Abstract: An outdoor microwave transceiver intrusion detector that alternately transmits pulses of RF energy at two different frequencies and uses range and direction of travel information derived from the phase of the two Doppler responses to optimize the signal processing and apply range dependent thresholds. The time delay between the onset of the transmitted pulse and the sample of the Doppler response is controlled to provide an accurate range cutoff. The two frequencies are selected so that the difference in phase of the Doppler response at the two frequencies increases from zero to ninety degrees as the target goes from the Transceiver to the maximum range. Digital signal processing is used to measure the difference in phase of the two Doppler responses and translate this information into location of the target. The location information is used to create a number of range bins.

Abstract: The invention detects a ghost occurring due to mispairing, reflections from a wall, or the like, and improves the ability of a radar to track targets when actual relative velocity changes by more than a certain value. If a stationary target is present within a prescribed region centered about a moving target, the stationary target is excluded from output data by determining it as being a target resulting from mispairing due to the detection of guardrail posts or similar structures. Further, a moving target that is expected to collide with an eligible target is also excluded from the output data by determining it as being a target resulting from mispairing due to the detection of a target having many reflecting points. For a moving target showing an unlikely relative velocity, pairing with some other peak is attempted by determining the moving target as being a target resulting from mispairing due to the detection of a plurality of moving targets moving in the same direction.

Abstract: The invention provides a millimeter wave radar monitoring system, which can reduce the installation cost and can improve reliability with less probability of false alarms. A millimeter wave radar unit includes a millimeter wave radar having a transmitting antenna for radiating a radio wave and a receiving antenna for receiving a wave reflected by a target having received the radio wave radiated from the transmitting antenna, and includes a signal processing unit for the received radio wave. A target tracking and monitoring circuit section in a monitoring unit collates position information of the target detected by the millimeter wave radar unit with monitoring area layout information held in a monitoring area layout signal section, thereby tracking a motion of the target. The target is displayed on a display along with the monitoring area layout information. When it is determined that the target is a suspicious invader, a warning device issues an alarm.

Abstract: A method and system for detecting airborne plant material, such as mold spores and pollen, and flying insects and birds, and classifying them as to whether they are harmful to field crops, production animals or other assets within a protected volume or area. Lasers, radar, and other types of radiation may be used to illuminate at least a perimeter around such assets to be protected, with radiation returns detected and applied to a pattern classifier to determine whether the detected objects of interest are harmful, benign or beneficial. In the event the objects are determined to be harmful (pests), a variety of measures controllable via the radiation returns may be taken to eliminate the harmful objects, these measures including firing pulses of laser, microwave or other radiation of a sufficient intensity to at least incapacitate them, or mechanical measures such as controlled drone aircraft to macerate the pests with propellers or spray limited amounts of pesticide in the area of the pests.

Abstract: Radar method and apparatus for detecting small, slow moving targets in the presence of high background clutter that includes a balanced bridge structure to achieve a null balance with the target and background clutter. Radar return signals from background objects as well as the targets are viewed by the radar as a composite single signature return. The invention uses a phase shifter to achieve a null balance even though the background clutter consists of many components at varying distances from the radar.

Abstract: A self-modulating, remote, moving target detector for intrusion alarms, vehicle detection, and remote speed and distance measurement that includes a remote continuous wave radar transceiver that is used to detect moving targets. The same frequency used for the radar transmission is modulated in a continuous manner in order to transmit radar data concerning a moving target to a remote location away from the radar transceiver. The transceiver oscillator is self-modulated by the reflected signal received from a moving target in the transceiver and retransmitted such that the primary radar signal becomes the information carrier concerning the moving target, which is received remotely, in order to activate an alarm or a display system showing the moving target. The system could be utilized with any frequency from audio to light, with RF and microwave of primary interest.

Abstract: A motor vehicle radar system having at least one sensor-radiation transparent body for focusing the sensor beam and/or at least one radome without intentional focusing in the beam path, at least one arrangement made of electrical printed circuit traces being arranged in the area of the sensor-radiation transparent body and/or the radome, the arrangement being suitable at least for heating the sensor-radiation transparent body and/or the radome, electrical power being able to be supplied to the electrical printed circuit traces, power control of the supplied electrical power being carried out as a function of operating states and ambient conditions, such that the surface temperature (TL) of the sensor-radiation transparent body and/or the radome does not exceed preestablished temperature values.

Abstract: The invention relates to a device for counting at least one person (7) that passes a passage having a floor. Said device comprises at least one distance sensor (3, 4) that emits a cone or rays (5, 6) from radar rays or ultrasonic waves, receives the reflected rays/waves and provides an evaluation device with the received signals. Said cone(s) of radiation (5, 6) cover(s) the entire width of the passage and is/are disposed at an angle with respect to the direction of movement of the person (7) passing the passage. The aim of the invention is to improve people counters known from the art where the distance sensors are often disposed above head height and to provide a counter which is simple in design and which can be disposed as inconspicuously as possible and without being noticed by the people passing the passage. To this end, the distance sensor (3, 4) is accommodated in a housing (1, 2) disposed on the floor.

Abstract: A method for a subject vehicle to avoid collisions is provided. At least one lane feeding into an intersection is scanned. The presence of a threat vehicle in the at least one lane is detected. Whether the subject vehicle and the threat vehicle will occupy the intersection at the same time is predicted. A warning is issued in response to the predicting.

Abstract: In a method and apparatus for controlling the distance of a vehicle to a vehicle traveling ahead, in which the distance and the relative velocity of the vehicle traveling ahead are measured and the distance, in a distance control mode, is controlled by accelerating or decelerating the vehicle to a preestablished setpoint distance, wherein the deceleration permitted by the distance control process is limited and, in situations in which the setpoint distance cannot be maintained at this limited deceleration, the transition is made from the distance control process to a process limiting the distance to a minimum distance which is smaller than the setpoint distance, and the vehicle, after reaching the minimum distance, is further decelerated, so that the distance once again increases to the setpoint distance.

Abstract: In a position detecting system used to monitor a suspicious person and to give an alarm by using a radar which transmits/receives a microwave or a millimeterwave, the shape of a detectable area of the radar and that of the area to be monitored are not always equal to each other, and thus, an alarm may be erroneously given in response to the object outside the area to be monitored. For its solution, the area to be monitored is surrounded by a plurality of reflectors, and the coordinate values of the reflectors and the detecting object are calculated based on the signals reflected from the reflectors and the detecting object and then compared. When the coordinate value of the detecting object is inside the area to be monitored, it is determined that the detecting object is an intruding person or the like and an alarm is given.

Abstract: An intrusion detection system and method are provided that can utilize impulse radio technology to detect when an intruder has entered a protection zone. In addition, the intrusion detection system and method can utilize impulse radio technology to determine a location of the intruder within the protection zone and also track the movement of the intruder within the protection zone. Moreover, the intrusion detection system and method can utilize impulse radio technology to create a specially shaped protection zone before trying to detect when and where the intruder has penetrated and moved within the protection zone.

Abstract: Apparatus for and methods of obtaining positional information about one or more objects in a detection field are disclosed. An array including a transmitting element and a plurality of receiving elements is provided. In one aspect a truncated cross-correlation function is applied to determine the interval between signals received by a plurality of the receiving elements, thereby to determine an angular position of an object. In another aspect a warning zone is defined and it is determined whether an object is within the warning zone. Also disclosed are techniques for stretching received signals, and techniques for obtaining positional information relating to an object using non-Doppler radar. Various implementations, modifications and applications of the techniques described are disclosed. Typical applications of the techniques described are with vehicles.

Abstract: A transmission wave is applied to a predetermined range in a width-wise direction of a vehicle. Objects ahead of the vehicle are recognized on the basis of reflected waves resulting from reflections of the transmission wave. Calculation is made as to a position of each of the objects and also a lane-sameness probability for each of the objects that the object and the subject vehicle are on a same lane. Object information pieces corresponding to the respective objects represent the calculated positions of the objects and the calculated lane-sameness probabilities for the objects. In cases where at least two objects become substantially equal in position, the two objects are recognized as a single object. One is selected from the two objects which relates to a calculated lane-sameness probability equal to or higher than a predetermined value. The single object takes over an object information piece corresponding to the selected object.

Abstract: A system and method for highly selective intrusion detection using a sparse array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array around the perimeter of a building. Each TM-UWB radar transmits ultra wideband pulses that illuminate the building and the surrounding area. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the inside of the building and the surrounding area. This image is used to detect motion in a highly selective manner and to track moving objects within the building and the surrounding area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.

Abstract: A fluid flow device includes an actuator, an RF transmitter, a gated RF receiver, and a processor. The RF transmitter is configured and arranged to produce a plurality of pulses of RF energy spaced apart in time to form a sensor field. The gated RF receiver is configured and arranged to receive RF energy reflected by objects within the sensor field. The processor is coupled to the gated RF receiver for evaluating the reflected RF energy. The processor is also coupled to the actuator and is configured and arranged to activate the actuator in response to the reflected RF energy to control fluid flow. In addition, a new low power radar sensor operates by providing radar pulses that are non-uniformly spaced in time. In operation, a burst of pulses is initiated in the transmitter. Between each burst is a period of rest time in which the transmitter is not transmitting RF energy.

Abstract: Systems and methods for networking detection devices associated with police activity are provided in a network that includes at least one server (180) and a number of client devices (130-150). Each of the client devices (130-150) transmits its location information to the server for storage. When a client device (130) receives detection information relating to radar activity, a police sighting or other police activity, that client device transmits the detection information to the server (180). The server (180) may then transmit the detection information to other client devices (140,150).

Abstract: Radar method and apparatus for detecting small, slow moving targets in the presence of high background clutter that includes a balanced bridge structure to achieve a null balance with the target and background clutter. Radar return signals from background objects as well as the targets are viewed by the radar as a composite single signature return. The invention uses a phase shifter to achieve a null balance even though the background clutter is consists of many components at varying distances from the radar.

Abstract: To provide an immersion object detection system capable of detecting an immersion object within a detection target area and specifying a position thereof irrespective of a short distance/long distance. A millimeter wave is irradiated to a detection area from a millimeter-wave RF unit through an antenna unit, and the reflected wave is detected. In the case that an immersion object exists in a short-distance area from a radar unit, the directly reflected waves from the immersion object is analyzed, thereby specifying the position of the immersion object, and in the case that the immersion object exists in a long-distance area from the radar unit, the position of the immersion object is specified in accordance with the position of the reflection member which cannot detect among the group of reflection members placed within the detection area.

Abstract: A compact, autonomous motion detecting and alerting system alerts to the movement of objects of interest. Mounted on an environmentally sealed PC board are a transceiver such as a CW radar front-end, connectors, signal processors and a communications device. The system provides early warning of movement of an ice sheet or rubble field via the communication device that may be a cellular telephone. This system is mounted proximate the target surface under observation, oriented at pre-specified offset angles both laterally and in elevation. The target is illuminated and energy reflected therefrom is mixed with a portion of the transmitted signal to produce a difference frequency signal that is processed to establish existence of motion within a pre-specified velocity range. Upon verification of motion, notification is sent to a responsible authority. An autonomous or semi-autonomous power source and integral power management function may be incorporated on the same PC board.

Abstract: The present invention provides a security system that can provide a user with data on the directional movement, velocity and location of an object within and around the perimeter of a structure with the use of radio energy. The system comprises a sensor unit having at least one antenna for transmission of a signal into a defined area of the structure. Any intrusion in the area is detected upon a change in the waveform received by the antenna. A received signal is transmitted from the sensor unit to a control unit, comprising, in part, a preprogrammed data processing unit that can determine the movement of the intruder. Utilization of a plurality of sensor units allows the user to obtain additional information on the velocity and location of the intruder. Additionally, as with conventional security systems, the system can provide an electrical signal to activate a sound and/or light device to attract the attention of the intruder and warn others of the intruder's presence.

Abstract: A multiple beam array antenna system comprises a plurality of radiating elements provided from stripline-fed open-ended waveguide coupled to a Butler matrix beam forming network. The Butler matrix beam forming network is coupled to a switched beam combining circuit. The antenna can be fabricated as a single Low Temperature Co-fired Ceramic (LTCC) circuit.

Abstract: A dual channel microwave sensor employs single sideband Doppler techniques in innumerable vibration, motion, and displacement applications. When combined with an active reflector, the sensor provides accurate range and material thickness measurements even in cluttered environments. The active reflector can also be used to transmit multi-channel data to the sensor. The sensor is a homodyne pulse Doppler radar with phasing-type Doppler sideband demodulation having a 4-decade baseband frequency range. Ranging is accomplished by comparing the phase of the Doppler sidebands when phase modulated by an active reflector. The active reflector employs a switch or modulator connected to an antenna or other reflector. In one mode, the active reflector is quadrature modulated to provide SSB reflections.

Abstract: A system for sensing and measuring the relative motion of an object, comprising a transceiver device configured to transmit a signal toward an object, a plurality of detectors offset in phase to receive the transmitted signal and a reflected signal, and a processor configured with logic to measure a phase shift resulting from the relative motion of the object between the transmitted signal and the reflected signal at the plurality of detectors, wherein the processor is further configured with the logic to relate the phase shift to the relative motion of the object.

Abstract: A method of detecting objects reflecting impulse waveforms of generating a detection envelope by receiving a reflected waveform, delaying said waveform by a peak-to-zero delay (PZD) interval. The PZD interval is the time between a maximum energy displacement in the impulse waveform and an adjacent zero crossing. The reflected waveform and its delayed version are squared and then summed to create the envelope. If the envelope is to be defined in terms of voltage, the root of the sum of the squares may be found. Also a method for generating an image using the PZD interval in back-projection techniques is described wherein a sampling point is chosen on each of a plurality of reflected waveforms. The values of the samples are summed and the waveforms are delayed by the PZD interval and the values of the sampling points are again summed. The two sums are squared and added together to generate an image envelope.

Abstract: An electronic circuit for a proximity sensor, which is target-independent and is based on a phase projection transformation, is configured in such a way that the oscillating circuit can be driven by a square-wave voltage. A synchronous demodulator is used for the phase projection transformation. The electronic circuit can be miniaturized and only low requirements are placed on the stability of the feed voltage. A method for operating a proximity sensor is also provided.

Abstract: A system and method for highly selective intrusion detection using a sparse array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array around the perimeter of a building. Each TM-UWB radar transmits ultra wideband pulses that illuminate the building and the surrounding area. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the inside of the building and the surrounding area. This image is used to detect motion in a highly selective manner and to track moving objects within the building and the surrounding area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.

Abstract: A method is described for detecting moving and/or stationary objects in the path of a vehicle, where the distance and velocity of the reflecting object are determined by using a radar sensor, where the frequency of the signal transmitted is modulated in the shape of a ramp according to a multi-ramp method, and some ramps have a lower slope in the frequency curve. The higher spectral components of the mixed signals from the ramps having the lower slope, which are to be assigned to a distance range of the reflecting object which is greater than the distance range belonging to the ramps having the greater slope, are used to determine the distance, speed and angle of objects.

Abstract: Radar apparatus in which output RF signals are modulated on an optical signal prior to transmission. Incoming optical echo signals are converted into RF signals using a detector. The original functionality of the radar apparatus is to a large extend retained, including the Doppler processing. The target radar cross section is determined by the wavelength of the optical signal.

Abstract: An apparatus for the detection of any intruder passing through an electronic fence is disclosed. The electronic fence is formed by a millimeter wave radar positioned at one end of the fence and a plurality of reflectors placed along the floor of the fence as well as on a structure at its far end. The fence is formed of a plurality of electromagnetic beams traversing between the radar antenna or antennas and each of the reflectors. A sufficient number of beams inhabit the fence volume to make traversing the fence by an intruder without detection essentially impossible. The radar reflection from the intruder's person is used to report the location of an intruder attempting to traverse the electronic fence near the radar end and is the secondary means of detection at greater ranges where breaking of one or more electromagnetic beams constitutes the primary means of detection.

Abstract: The method and apparatus for detecting a moving object through a barrier uses radar imaging and a multiplicity of spatially separated antennas to acquire full-waveform radar data that accurately represents the measurement of the propagating wavefield. The data is enhanced by subtracting an estimate of previously recorded background data, and beamforming of the enhanced data is performed to compute an image from the data provided on multiple channels.

Abstract: The method and apparatus for detecting a moving object through a barrier uses radar imaging and a multiplicity of spatially separated antennas to acquire full-waveform radar data that accurately represents the measurement of the propagating wavefield. The data is enhanced by subtracting an estimate of previously recorded background data, and beamforming of the enhanced data is performed to compute an image from the data provided on multiple channels.

Abstract: An intrusion detection system and method are provided that can utilize impulse radio technology to detect when an intruder has entered a protection zone. In addition, the intrusion detection system and method can utilize impulse radio technology to determine a location of the intruder within the protection zone and also track the movement of the intruder within the protection zone. Moreover, the intrusion detection system and method can utilize impulse radio technology to create a specially shaped protection zone before trying to detect when and where the intruder has penetrated and moved within the protection zone.

Abstract: Blade tracker apparatus for tracking rotating helicopter blades includes an antenna which transmits a signal beam in the direction of the rotating blade. The impedance of the antenna changes as one of the blades enters the transmission beam and the amount by which the impedance changes varies as a function of the physical distance between the antenna and the blade. The varying impedance caused by a blade passing the antenna will amplitude modulate the transmitted signal and provide an indication of the distance of each of the several blades of a rotor as each of the blades passes through the field of the antenna.

Abstract: A radar device in which a much more precise demodulation can be made with an inexpensive circuit, free of the output variation of the frequency-modulated transmission signal. The radar device includes an oscillator which produces and outputs a frequency-modulated electromagnetic wave to a switching circuit by way of a directional coupler. The switching circuit uses switching modulation to radiate the electromagnetic wave from a transmitting antenna. The radiated electromagnetic wave after being reflected from an obstacle is received at a reception antenna. A mixer mixes this reception signal and a local signal fed from the directional coupler to produce a mixing signal which is to be fed to a high pass filter. The high pass filter deletes a low frequency output variation noise which is contained in the mixing signal and which occurs in the frequency modulation in the oscillator. The resulting mixing signal is, with the noise deleted, fed by way of an AC amplifier, to a switching demodulating circuit.

Abstract: The present invention provides a security system that can provide a user with data on the directional movement, velocity and location of an object within and around the perimeter of a structure with the use of radio energy. The system comprises a sensor unit having at least one antenna for transmission of a signal into a defined area of the structure. Any intrusion in the area is detected upon a change in the waveform received by the antenna. A received signal is transmitted from the sensor unit to a control unit, comprising, in part, a preprogrammed data processing unit that can determine the movement of the intruder. Utilization of a plurality of sensor units allows the user to obtain additional information on the velocity and location of the intruder. Additionally, as with conventional security systems, the system can provide an electrical signal to activate a sound and/or light device to attract the attention of the intruder and warn others of the intruder's presence.