Abstract: A method and apparatus for a co-located Radio Frequency Identification (RFID) device and ultrasonic device includes an RFID reader loop antenna element oriented parallel to a reflector panel. An ultrasonic emitter is disposed through an aperture in the reflector panel with a horn that extends through the loop element. The horn can serve as a mounting structure for the antenna element. A diameter of the aperture is less than one-quarter wavelength of an operating frequency of the RFID reader loop antenna element. The aperture is located in the reflector panel near a minimum E-field area of the RFID reader loop antenna element.

Abstract: A system for determining a propagation direction of a received electromagnetic wave includes a linear phased array of receiving antenna elements and a processing unit for processing signals received by the receiving antenna elements. The processor is arranged for generating, from the received signals, receiving data corresponding to a set of respective angular synthetic receiving aperture beams.

Abstract: A wireless short range radio-frequency master device adapted to create and maintain a portable private network of wireless short range radio-frequency slave devices wherein the master device is configured to detect and register suitable slave devices for a network, and is capable of determining the proximity of any registered slave device with respect to the master device in use, the master device further being adapted to enable a user to define two or more groups of registered slave devices selected from the total number of registered slave devices and to enable a user to select a defined group of such registered slave devices as an active group, thereby forming an active portable private network of wireless short range radio frequency devices comprising the master device and selected registered slave devices within the selected group.

Abstract: A base may locate a remote control by transmitting a first location signal, receiving a second location signal at base receivers from a remote control device transponder transmitted in response, and calculating a location of the remote control device based on the received second location signal. The base may provide navigation information based on the calculated location. In some implementations, the base may perform a setup routine by providing an interface that accepts position information, accepting an indication that the remote control is located at a position, transmitting a first calibration signal, receiving a second calibration signal at the receivers transmitted by the transponder in response, and recording baselines for the position. When the base unit subsequently analyses a second location signal to calculate a location of the remote control, the base may base the calculated location at least partly on the baselines.

Abstract: Methods for flying multiple aircraft in a predetermined formation in which a relative navigation grid is emitted from at least one of the aircraft, a spatial relationship is calculated based on the emitted relative navigation grid, and a relative position of at least one aircraft is altered to position the aircraft in the predetermined formation when the spatial relationship does not conform with the predetermined formation.

Abstract: Embodiments of the present invention disclose systems and methods for providing an avionics overlay data link. Through embodiments of the present invention, existing ATC (or other) modulated signals using existing frequencies (or other frequencies) may be utilized to transmit (e.g., from an aircraft transponder) additional information in a manner that does not render the transmitted signal unrecognizable by legacy ATC equipment. In various embodiments, legacy equipment may demodulate and decode information that was encoded in the transmitted signal in accordance with preexisting standard modulation formats, and updated equipment can also extract the additional information that was overlaid on transmitted signals.

Abstract: A number of apparatuses are provided, for sensing and/or emitting energy along one or more desired apparatus line of sights (LOS) with respect to the respective apparatus. In at least one embodiment, the apparatus includes an assembly that is rotatably mounted on a base with respect to a switching axis. The assembly has two or more sensing/emitting units, each having a respective sensing/emitting unit line of sight (ULOS). Each sensing/emitting unit has an operative state, wherein the respective unit ULOS is pointed along a LOS of the apparatus for sensing and/or emitting energy along the LOS, and a corresponding inoperative state, where the respective unit ULOS is pointed along a direction different from this LOS. A switching mechanism enables switching between the sensing/emitting units to selectively bring a desired sensing/emitting unit exclusively into its respective operative state while concurrently bringing a remainder of the sensing/emitting units each to a respective non-operative state.

Abstract: An RF signal detection process by incorporating direction detection of the RF signal along with energy detection to arrive at a signal of interest (SOI). The SOI is identified by matching direction detections and energy detections. Low-level and noise-like signals can be reevaluated for unresolved direction detections or energy detections. The RF signal detections can be filtered based on valid direction detections very early on in the processing chain to reduce the amount down-stream processing required.

Abstract: In an embodiment, a quantity smoother includes a first stage and a second stage. The first stage is operable to receive a sequence of raw samples of a quantity and to generate from the raw samples intermediate samples of the quantity, the intermediate samples having a reduced level of fluctuation relative to the sequence of raw samples. The second stage is coupled to the first stage and is operable to generate from the intermediate samples resulting samples of the quantity, the resulting samples having a reduced level of fluctuation relative to the sequence of intermediate samples. For example, such a quantity smoother may be part of a target-ranging system on board a fighter jet, and may smooth an error in an estimated target range so that the fighter pilot may more quickly and confidently determine in his head a range window within which the target lies.

Abstract: A system for estimating a location of the source of a projectile includes a radar system for transmitting a wave and detecting and providing an indication of a wave reflection from the projectile, an acoustic detection system for detecting and providing an indication of at least one sound associated with the projectile, and circuitry for estimating the location in response to the indication of a wave reflection and the indication of at least one sound.

Abstract: A system for classifying targets utilizes radar receptions and acoustic signatures of armament projectiles (e.g., bullets from celebratory rifle fire, mortars, cannon fire, artillery shells, or rockets, etc.) to associate ordinances with radar returns to better utilize a radar's resources to acquire and track targets of interest. In one embodiment of the invention the system for classifying targets comprises: a radar system for detecting targets based upon radar receptions; an acoustic system for detecting targets based upon acoustic receptions; and a means for classifying the acoustic receptions into target types; a means for computing range, bearing and time of incidence for the radar receptions and the acoustic receptions; a means for associating the radar receptions and the acoustic receptions according to the classification.

Abstract: A method is provided for mobile device enabled radar tags. A signal is transmitted to a radar tag. The radar tag detects the signal. The radar tag provides information. The information is received from the radar tag. A location of the radar tag is determined based on the information. The radar tag is identified based on the information. The identification of the radar tag, the location of the radar tag, and a time associated with determining the location of the radar tag are recorded as data in a database. The radar tag is evaluated based on accessing a plurality of recordings of the data in the database.

Abstract: A system and method for warning a helicopter of an approaching bullet using existing sensor systems is disclosed. The disclosed method including the steps of: detecting and providing bearing information for detected small arms weapon firing locations near the helicopter, determining a detection area and detection time window for the fired bullet, determining the antennas of the RF transmitting and RF receiving systems covering the bearing of the detected weapon firing; determining a timing sequence and allocating time segments for transmitting and receiving RF signals during the detection time window, commanding the RF emitting system to emit and the RF receiving system to receive RF signals during their allocated time segments, processing RF signals received and determining whether reflected RF signal pulses from the emitted RF signal pulses are present, and outputting a warning where reflected RF signal pulses are detected.

Abstract: Disclosed is an Radio Frequency (RF) receiving system methodology, utilizing an Luneberg Lens having a spherically shaped outer surface and a semi-spherical shaped focal surface composed of near-equally spaced frequency-independent antenna elements disposed uniformly to cover the semi-spherical focal surface of the Luneberg Lens; and radio frequency (RF) power splitters and combiners for combining the RF energy received by the antenna elements; forming rows and columns; thereby reducing the number of required RF receiver channels for subsequent processing, where the maximum row/column and differential amplitude comparison is used for deriving volumetric direction finding (DF) of intercepted signals; as part of a robust signal detection and direction-finding (DF) system; for detecting and processing a plurality of signals emanating from surface and airborne platforms within the hemisphere, where each surface and airborne platform include transmitters for transmitting navigation, communication and radar signals

Abstract: The present invention relates to systems and methods of tracking and/or avoiding harm to certain devices or humans. According to one exemplary embodiment, a method of tracking individual assets may include obtaining position data of an asset via a GPS receiver in communication with a position sensor associated with the asset, processing position data and sensor data via a processing component associated with the position sensor that receives the position data from the GPS receiver, and communicating sensor data to a host device via a communication interface associated with the position sensor and configured to enable wireless communication between the position sensor and the host device.

Abstract: A radar device separates directions of a plurality of targets, obtained from combinations of antenna beams, with a high accuracy. The radar device includes: a direction calculating unit for calculating a primary direction, which is the direction of a target, from a combination of characterizing quantities calculated by a signal detector from the reception waves of at least two beams that partially overlap, among the beams radiated in the plurality of directions; and a direction integrating unit for, when a plurality of primary directions calculated by the direction calculating unit is present, calculating an integrated direction, which is the true target direction, from an area in which distribution of the plurality of primary directions is a predetermined density or greater, based on the primary directions belonging to the area.

Abstract: An apparatus for detecting radiation includes an entry window configured to receive radiation from a target, the entry window having an outer surface and an inner surface, such that the outer surface is not parallel to the inner surface. The apparatus further includes a radiation transmission assembly configured to receive at least a portion of the radiation received by the entry window. The apparatus further includes a radiation sensor configured to receive at least a portion of the radiation from the radiation transmission assembly.

Abstract: An optical detection system for detecting launch of an offensive projectile. The detection system includes an image detector array, an optical arrangement for focusing on to the image detector array, and a processing system associated with the image detector array. The processing system is configured to derive a series of frames from the image detector, to process the series of frames to identify a flash event and to generate and output that indicates a direction of the flash event.

Abstract: In one embodiment, a system includes at least two detector devices, each detector device for independently detecting a phase event of a composite signal comprising one or more traveling wave signals to provide phase event information. The system further includes a processor configured to receive the phase event information from each detector device and to estimate a direction of arrival of at least one of the traveling wave signals based on the phase event information.

Abstract: A method and apparatus for use in determining the range in a single time sample from a platform to a target are disclosed. The method includes receiving radiation emanating from the target at two points on the platform in a common time sample; detecting the received radiation and generating a signal representative thereof; and processing the signal. The signal is processed to determine a respective angle to target from two points on the platform by using a correlation between received signal amplitude and respective angle; and determine the range from the platform to the target from the respective angles and the separation distance between said two points in a single signal-to-noise sufficient sample. The apparatus includes a plurality of optical channels through which the apparatus can receive radiation emanating from the target, the optical channels and a plurality of electronics.

Abstract: A surveillance system is provided for surveillance of objects within a secure area. A surveillance sensor transmits surveillance signals to all objects within the secure area, the reflections of which are received back by the surveillance sensor to determine the locations of objects, and communicates the determined locations to a pressing facility. Objects authorized to be in the secure area are equipped with an Identification Friend or Foe (IFF) unit that includes a GPS receiver and a data communication transmitter. In response to predetermined conditions, the IFF units broadcast their position and identification to the processing facility for correlation with locations defined by the reflection signals.

Abstract: A detection device is described configured for receiving radar and laser signals. The detection device is a self contained stand alone assembly having a watch like configuration and positionable on an arm of a vehicular driver such as a motorcyclist. The detection device is a warning receiver configured to receive signals, identify the signals as being in frequency bands for vehicular speed measuring systems used in law enforcement, and providing a warning to the vehicular driver. In addition, the detection device is configured for calculating the angle and distance from the detection device to the source of the speed measuring system.

Abstract: The present invention relates generally to a combined radar and laser detector that enables a driver to drive safely and, more particularly, to a combined radar and laser detector, in which a signal receiving module for receiving various kinds of signals including traffic information and an information display module for informing a driver of the signals are separated, the signal receiving module and information display module are constructed to communicate with each other using wireless communication, and the information display module is integrated with a Global Positioning System (GPS) receiver detecting GPS data related to the location and speed of a moving vehicle, so that the combined radar and laser detector can not only provide accurate traffic information to the driver, but also allow the installation thereof to be easy, the miniaturization thereof to be achieved, and power consumption to be minimized.

Abstract: An identification interrogator is provided for surveillance of objects within an area. The identification interrogator transmits interrogation signals to all objects within the surveillance area, the reflections of which are received back by the interrogator to determine the locations of the objects, and communicates the determined locations to a processing facility to determine their authorized locations. Upon receipt of interrogation signals, some of the objects within the surveillance area broadcast their position and identification to processing facility for correlation with the locations determined by the reflection signals. The locations of other objects are found by correlating the location determined by the reflection signal with a predetermined list of objects and their location within the surveillance area. These may be objects with no means or method to transmit position and identification information, such as rock formations or buildings.

Abstract: An identification interrogator is provided for surveillance of objects within an area. The identification interrogator transmits interrogation signals to all objects within the surveillance area, the reflections of which are received back by the interrogator to determine the locations of the objects, and communicates the determined locations to a processing facility to determine their authorized locations. Upon receipt of interrogation signals, some of the objects within the surveillance area broadcast their position and identification to processing facility for correlation with the locations determined by the reflection signals. The locations of other objects are found by correlating the location determined by the reflection signal with a predetermined list of objects and their location within the surveillance area. These may be objects with no means or method to transmit position and identification information, such as rock formations or buildings.

Abstract: A method of determining a target location from a vehicle is described. The method includes identifying the target utilizing a video system, determining an angular location vector to the target with respect to the vehicle, determining a position of the vehicle utilizing a digital terrain elevation map and precision radar altimeter, calculating a location where the angular location vector would intersect with the digital terrain elevation map, and generating a target position based on vehicle position and the location of the intersection of the angular location vector and digital terrain elevation map.

Abstract: A system for the detection and determination of the success of interception of incoming missiles, used in conjunction with a defense weapon system capable of identifying and tracking incoming missiles and interceptors. The system comprises at least one of a plurality of sensing units. Each sensing unit comprises: an optical sensor for detecting optical signals within a predetermined range; tracking means coupled to the optical sensor for tracking an intercepting missile or an incoming missile; processing means for processing optical input detected by the optical sensor and analyzing the optical input to identify an optical signature and determine detonation of interceptor or incoming missile; communicating means for communicating data between the sensing unit and the defense weapon system; and control means for controlling the tracking means, the processing means and the communicating data.

Abstract: A method and apparatus for detecting and locating leaks in buried pipes is disclosed in which ground penetrating radar, induction, acoustic, and vacuum excavation systems are selected based on soil conditions and then employed in selected combinations. The conductivity and wave speed of the soil are used in the selection process and in the process of detecting and locating a leak based on the measurements obtained from the selected combination of detection systems.

Abstract: The present invention relates to a wide-band radar detector with an electronic compass integrated therein. The radar detecting unit includes a horn antenna, a signal processing unit for detecting signals received by the horn antenna, a laser module for receiving laser signals, a central processing unit for controlling the detection of the signals, a visual display means for visually displaying the detected signals, and a voice producing means for outputting the detected signals to a speaker. The electronic compass includes a magneto-inductive sensor for sensing the earth's magnetic field and a sensor controlling unit. The sensor controlling unit then transmits the values sensed by the magneto-inductive sensor to the central processing unit.

Abstract: Existing positioning technologies used in conjunction with Ground Penetrating Radar (GPR) are generally too time-consuming or insufficiently accurate for high resolution, high frequency, 3-d structural investigations. The invention provides an optical positioning system for use in GPR surveys that uses a camera mounted on the GPR antenna that takes video of the surface beneath it and calculates the relative motion of the antenna based on the differences between successive frames of video. Positioning accuracy to within several millimeters is provided. The procedure is orders of magnitude faster than surveying a grid of data points or laying out parallel lines and surveying each line with an odometer wheel. The system and method of positioning is suitable for mapping the subsurface of structures such as building columns or floors using GPR. Time domain synthetic aperture radar algorithms can be used to reconstruct an image of the subsurface using this position data.

Abstract: A method for estimating an arrival direction of a desired wave in which the arrival direction of the desired wave can be estimated even in case of existence of a multiple reflection wave. An identical signal series is repetitively transmitted two or more times from a transmitting side. The transmitted signal series is received by an array antenna having a plurality of element antennas on a receiving side. When the signal is received by each of the element antennas, cross-correlation is calculated between the signal series corresponding to the different repetition of the signal transmission from the transmitting side. Then, a MUSIC algorithm or an ESPRIT algorithm using the cross-correlation matrix is applied to estimate the arrival direction of the desired wave.

Abstract: The present invention relates to a wide-band radar detector with an electronic compass integrated therein. The radar detecting unit includes a horn antenna, a signal processing unit for detecting signals received by the horn antenna, a laser module for receiving laser signals, a central processing unit for controlling the detection of the signals, a visual display means for visually displaying the detected signals, and a voice producing means for outputting the detected signals to a speaker. The electronic compass includes a magneto-inductive sensor for sensing the earth's magnetic field and a sensor controlling unit. The sensor controlling unit then transmits the values sensed by the magneto-inductive sensor to the central processing unit.

Abstract: A detector device for detecting the presence of a speed detection system which includes a displaying means which pivots in relation to the device's housing thereby allowing a user to selectively adjust the orientation of the display to maximize the display's visual output without detracting from the alignment/orientation of the device's detection means.

Abstract: A protective device for a person, specifically for a person participating a sport, having at least one sensor device for detecting obstacles in the vicinity of the person to be protected; an evaluation device having a microcontroller for a situation evaluation with respect to the surroundings of the person to be protected; a triggering device for activating a protective application; and a protective application, which can be integrated in the equipment of the person to be protected.

Abstract: When a question signal of a transmitting frequency band &Dgr;F1 output from a radar device is received in search and rescue radar trans-ponder (SART) of a wreck ship, a response signal is sent from the SART to the radar device. In the radar device, the response signal and an echo of the question signal are received as a reception signal, intensity of components of the reception signal placed in almost the same frequency band as the transmitting frequency band &Dgr;F1 of the question signal is suppressed to produce a filtered response signal, and components of the filtered response signal placed in a receiving frequency band &Dgr;F2, which does not overlap with the transmitting frequency band &Dgr;F1 of the question signal, are extracted from the filtered response signal as an image signal.

Abstract: A police radar and laser detector with networking capability is disclosed. By including the ability to wirelessly transmit the existence or even location of a detected radar or laser source, overall performance can be improved. Transmission of an actual radar or laser location gives other detectors advanced warning. Additionally, transmission of false alarm locations will allow other detectors to reduce false alarms.

Abstract: Interrogators, wireless communication systems, methods of operating an interrogator, methods of monitoring movement of a radio frequency identification device, methods of monitoring movement of a remote communication device and movement monitoring methods are provided. According to one aspect, an interrogator includes communication circuitry configured to output a forward wireless signal to a radio frequency identification device and to receive a return wireless signal from the radio frequency identification device; and a processor coupled with the communication circuitry and configured to process the return wireless signal to monitor movement of the radio frequency identification device.

Abstract: A method (200, 300) and apparatus (100) provides for displaying locally the position and identity of various field operatives or agents who have radio receiver transmitters (20, 30 and 40). A local control station (10) transmits a request for identification to radios (20, 30 and 40). Each radio responds back with a message (226) giving its location. The local control station then displays the identity and location of the unit on an area map (234) and stores the information in memory (236). Control station 10 further designates some or all of the radios (20, 30 and 40) with a laser designator signal (60). The radio then responds with an IFF signal (318) if it is a friendly agent.

Abstract: A radio direction finder based on the simulated Doppler frequency shift principle is disclosed that is applicable to FSK encoded pulsed transmissions. Typical applications include tracking of stolen vehicles or shipped package tracking. During FSK decoding, all antenna elements of the antenna array are turned on in a non-rotating mode thus eliminating error due to the simulated antenna rotation modulation while providing enhanced gain for the FSK decoder circuit. After decoding a suitable FSK signal, a virtual antenna rotation is enabled, and the bearing is measured during the time interval when the transmitter is only broadcasting a carrier wave.

Abstract: A precision direction finding system for making precision angle of arrival estimates for a signal received through two antenna elements separated in space. Phase interferometry is used to determine a precise angle of arrival, with multiple ambiguities due to the periodic nature of the phase difference related to geometric angle. The interferometric ambiguities are resolved using the time difference of arrival (TDOA) of the signal at the two antenna elements. TDOA is measured using leading edge envelope detection for simple pulsed signals, and predetection correlation for phase and frequency modulated signals.

Abstract: In a radar target position detecting apparatus, beams (, for example, light beams) irradiated from a transmitter(, for example, LED) have a predetermined divergence angle, a plurality of light (beam) receiving elements such as photodiode arrays each having a different receiving angle (directivity) are arranged in an array form, and a direction of a reflected wave (beam) is identified according to a position of the arrayed beam (wave) receiving elements in the array at which the reflected wave (beam) is captured.

Abstract: The invention provides a detection object searching device which makes it possible to immediately know the direction of a mobile detection object such as a car by information presented on a display of a portable unit. The detection object searching device includes a portable operation unit and a body unit. The operation unit includes a transmission section for transmitting a search signal upon operation of a transmission button, a receiving section for receiving a direction indication information signal, an absolute direction detecting section for generating an absolute direction signal, a control section for generating direction indication information indicating the direction of the car based on the direction information signal and absolute direction signal, and a display section for displaying the direction indication information.

Abstract: A sensor system comprises a plurality of sensor stations of the same type for surveillance of an area intended to include an object to be protected, the sensor stations being distributed essentially along the periphery of a circle, in the central part of which an object to be protected is intended to be contained. Each sensor station includes a detector unit which is arranged to scan an arc in an azimuth sector of the circle allocated to it up towards the background of the sky in each of two detection fields formed along the arc having different elevation angles with respect to the detector unit. The time of the passage of a target between the two detection fields is measured, and the target position is calculated relative to the sensor station on the basis of the measured time, the speed of the target, the angle between the detection fields and the angle to the target.

Abstract: A method for determining the direction to a signal source by cooperation between a first device which determines the direction to the signal source with a low angular accuracy and a second device which determines the direction to the signal source with a high angular accuracy. In a first step, the direction to the signal source is determined within a certain angular range and, through analysis of the signal transmitted from the signal source, the category of the signal source is determined. In a subsequent second step, an angular search for a signal source of said category is performed within the angular range, in which the search is interrupted in the direction in which a signal of the category is detected. In a subsequent third step, the detected signals are correlated with respect to time. When correlation is present, the direction to the signal source is determined by determination of the direction in which the signal source is detected.

Abstract: A detection system will detect and identify self-propelled objects, such as missiles, which create a hot exhaust plume. The exhaust plume has radiation which flickers with a frequency range of interest. This frequency range can be detected with various detectors, such as an ultraviolet detector or radio frequency detector. A warning signal will indicate if frequencies are encountered within the frequency range of interest. The detecting system will also detect light and radio frequency radiation from pressure waves created by supersonic components of the flying object. This radiation has low frequency components which can be filtered and identified.

Abstract: A system for reducing co-channel interference includes a power spectrum analyzer which provides a spectral signal representative of an intermediate frequency signal from the receiver of a direction finding system. The system further includes threshold/window logic that, responsive to the comparison of threshold levels and spectral windows to the interfering signals, will provide stop and continue signals to an integrator. The integrator receives signals from the direction finding system and stops and starts integration of the output signal responsive to the threshold logic. In so doing, co-channel interference is substantially reduced.

Abstract: A circuit arrangement that utilizes digital data representative of the amplitude of an RF pulse envelope is disclosed. The circuit arrangement comprises a PROM having prestored and addressable routines and a nine stage sequentially arranged eight (8) bit latches that are clocked at a rate of 25 nanoseconds. The circuit arrangement determines, within 25 nanoseconds, when the maximum value of the RF pulse envelope is within a selectable 6 dB or 3 dB point and generates a control signal SV that causes the data in the upper stages of the nine stage latches to be frozen and further generates an address that is routed to the PROM, wherein a family of waveform shapes are accessed. The circuit arrangement provides for four (4) data points that are examined by prestored routines of the PROM and compared against the prestored family of waveform shapes, and, upon a match therebetween, determines the time of arrival (TOA) and pulse width of the RF pulse envelope being received by the circuit arrangement.

Abstract: A surveying instrument for satellite position-measuring includes, a range finder (2), which is preferably non-contact-measuring and tiltable, combined with a satellite receiver (1) in a geometrically unambiguously defined relative position. These two instrument parts are mounted geometrically unambiguously in common plumb rod (3) or on a measurement stand. A vertical sensor (4) and a sighting device (5) are additionally provided, whereby simultaneous monitoring and setting respectively of the vertical direction and of the direction of the range finder measurement beam is permitted. Using the instrument, it is also possible to determine, in terms of coordinates, such points which formerly could not be surveyed using satellite position-measuring systems.

Abstract: In an aircraft on-board radar arrangement including a search radar and a radar warning receiving system, an additional receiving branch is provided to which are fed foreign radar signals received by the sharply focused transmit/receive antenna of the search radar, with the output of the additional receiving branch being connected to the radar warning receiver. This results in a greater angular resolution and a considerable increase in range, which again leads to a more detailed and early detected of threatening situations. By using already available components and because of the simple configuration of the additional receiving branch, additional costs remain low.

Abstract: A system for detecting the approach of a vehicle toward the line of sight an antenna comprises an alerter for receiving an acoustic noise signal from the vehicle and determining whether the signal is increasing or decreasing. The increase of a noise signal indicates the approach of a vehicle and is used to activate a power supply to supply power to a digital signal processor. The digital signal processor receives the acoustic signal and performs a comparison to determine whether the signal in fact is noise produced by a vehicle. If so, the digital signal processor activates a radar based primary sensor which more accurately detects the approach of the vehicle and determines the instant at which the vehicle passes an antanna of the sensor. When the vehicle passes the antenna, the digital processor receives data and produces an output signal that can be used to activate a counter to count the passage of vehicles, surveillance equipment or to fuse a mine if the vehicle is assumed to be hostile.