Abstract: Described herein are systems and methods for improving detection of a return signal in a light ranging and detection system. The system comprises a transmitter and a receiver. A first sequence of pulses may be encoded with an anti-spoof signature and transmitted in a laser beam. A return signal, comprising a second sequence of pulses, may be received by the receiver and the anti-spoof signature extracted from the second sequence of pulses. If based on the extraction, the first and second sequences of pulses match, the receiver outputs return signal data. If based on the extraction, the first and second sequence of pulses do not match, the return signal is disregarded. The system may dynamically change the anti-spoofing signature for subsequent sequences of pulses. Additionally, the first sequence of pulses may be randomized relative to a prior sequence of pulses.

Abstract: A corner sensor for a motor vehicle capable of communicating over a wireless communication link with an authentication device and including: an array of antennae; and an electronic control unit configured to: determine the phase difference between the segments received by the antennae; determine the probability of each angle of incidence over a range of angles that is predetermined on the basis of the determined phase differences and of a predefined table, so as to determine a probability profile; measure the power of the segments received by the antennae of the array of antennae so as to determine a power profile; determine the actual angle of incidence of the signal by multiplying the probability profile with the power profile; and send the value of the determined actual angle of incidence to a central electronic control unit of the vehicle.

Abstract: A method comprising: providing an autonomous vehicle (AV) with a first estimated position of a target; directing the AV to travel toward the first estimated position at a constant velocity; receiving echo signals of transmitted sonar signals, the echo signals indicating a range and an azimuth of the target; determining a depth difference of the AV and the target based on the received echo signals, the depth difference being determined based on changes to the range and azimuth of the target over time; and in response to a depth difference existing, re-directing the AV toward a second estimated position of the target generated from the depth difference.

Abstract: A network for providing high speed data communications may include multiple terrestrial transmission stations that are located within overlapping communications range and a mobile receiver station. The terrestrial transmission stations provide a continuous and uninterrupted high speed data communications link with the mobile receiver station employing a wireless radio access network protocol.

Abstract: A redundant power supply system for aircraft seats, includes: a first power supply module having a first AC to DC power converter configured to supply power to a first auxiliary board, the first auxiliary board being configured to supply power to a plurality of aircraft seats via a plurality of communication bus channels; a second power supply module having a second AC to DC power converter configured to supply power to a second auxiliary board, the second auxiliary board being configured to supply power to the plurality of aircraft seats via the plurality of communication bus channels; and a power supply link configured to connect the first auxiliary board and the second auxiliary board enabling the first AC to DC power converter to power the second auxiliary board via the power supply link.

Abstract: A device for checking the consistency of a positioning includes: a transmitter, a receiver, a time measuring unit, a distance determining module and a check module. The transmitter emits at least one signal, and the receiver receives at least four response signals from at least four different response elements. A response element receives the at least one signal and, upon receipt, emits a response signal. The time measuring unit determines, for each response signal, a total delay time from a transmission time of the signal and a reception time of the respective signal. The distance determination module determines a distance to the respective response element based on each total delay time, and the check module performs a consistency check of a determination of a position based on distances to the different response elements. With the device, erroneous distance values may be detected in ground-based positioning systems.

Abstract: In some examples, a system is configured for determining an estimated altitude of a melting layer, and the system includes a weather radar device configured to transmit radar signals and receive reflected radar signals. In some examples, the system also includes processing circuitry configured to determine the estimated altitude of the melting layer based on the reflected radar signals.

Abstract: The invention relates to a method for detecting at least one object (9a, 9b, 9c) in a surrounding area (7) of a motor vehicle (1) by means of a driver assistance system (2), in which a transmission signal is transmitted in each of chronologically consecutive measurement cycles via a distance sensor (4), and a first and a second echo of the transmission signal reflected by the at least one object (9a, 9b, 9c) are received; and, by means of a control device (3), a first distance value (a1) is determined based on the first echo, a second distance value (a2) is determined based on the second echo, and a height of the at least one object (9a, 9b, 9c) is determined based on the first and the second distance value (a1, a2); wherein the measurement cycles are carried out during a relative movement of the motor vehicle (1) with respect to the at least one object (9a, 9b, 9c); in at least two of the measurement cycles, a difference value is determined in each case, which describes a difference between the second distan

Abstract: A beam pattern of a base station antenna is refined when communicating with multiple aircraft, so that interference to adjacent beams from the base station are reduced. The method include receiving position locations from each of multiple aircraft. The method also include the receipt of an attitude of each of the aircraft as well as receipt of measurements of the pilot signals from each of the aircraft. The pilot signals were transmitted by the base station. The method also include the adjustment of an amplitude and a phase of a signal driving at least one antenna transmit element to refine the beam pattern. The adjustment is based at least in part on the pilot measurements, the position locations, and the attitude of each of the aircraft.

Abstract: A signal processing system including a plurality of receivers configured to receive a return signal from a transmitted radio frequency (RF) waveform. A mode control processor is configured to selectively and independently alter at least one characteristic of a signal down conversion process performed by each receiver. A digital signal processor is configured to integrate the outputs of the plurality of receivers.

Abstract: A non-transitory computer-readable recording medium stores a ship track data display program that causes a computer to execute a process including: first extracting particular ship track data for a set of particular ships with a relative distance therebetween being within a predetermined range, from ship track data for a plurality of ships; second extracting a place where a distance between ship tracks thereof is at a local minimum, from the particular ship track data; and associatively displaying, for the place, point data of a ship that previously arrives at the place, in the set of particular ships, and point data of another ship at a point of time when the ship that previously arrives at the place arrives at the place.

Abstract: A signal processing device according to an exemplary embodiment of the inventive concept can integrate a power amplifier, a duplexer, and a linearizer as a module to improve the convenience of management and to improve flexibility and extensibility so as to be transformable corresponding to a change in system development concept.

Abstract: A signal processing device according to an exemplary embodiment of the inventive concept can integrate a power amplifier, a duplexer, and a linearizer as a module to improve the convenience of management and to improve flexibility and extensibility so as to be transformable corresponding to a change in system development concept.

Abstract: A multiple input multiple output (MIMO) antenna for a radar system includes a receive antenna, a first transmit-antenna-arrangement, and a second transmit-antenna-arrangement. The receive-antenna is configured to detect radar-signals reflected by a target toward the receive-antenna. The first transmit-antenna-arrangement includes a first vertical-array of radiator elements and a second vertical-array of radiator elements. The first transmit-antenna-arrangement is configured so the first vertical-array can be selectively coupled to a transmitter independent of the second vertical-array. The second transmit-antenna-arrangement includes a third vertical-array of radiator elements and a fourth vertical-array of radiator elements. The second transmit-antenna-arrangement is configured so the third vertical-array can be selectively coupled to a transmitter independent of the fourth vertical-array.

Abstract: Systems and methods for use in generating alerts regarding terrain near aircraft are provided. A method includes determining a location of interest relative to an aircraft using a terrain awareness and warning system. The method further includes calculating a distance value and a bearing value for the location of interest relative to the aircraft. The method further includes providing first display data to an electronic display and providing second display data to the electronic display. The first display data is configured to cause the electronic display to show an aircraft situation display image indicating the location of interest relative to the aircraft. The second display data is configured to cause the electronic display to show the calculated distance value and the calculated bearing value.

Abstract: Road network data can include two dimensional (2D) coordinates corresponding to junctions and non-junctions in the road network. Height values for roads at junctions can be obtained from optimizing a cost function or as input. Height values for roads at non-junction locations can be obtained from a height function defined using the height values for the junctions. Pitch, yaw, and roll vectors can be obtained for non-junction locations using the height function, the 2D coordinates, and one or more road parameters, respectively. These vectors can define a coordinate frame for the road, along with which a width can provide points for defining polygons for the road. Road surface data can be constructed from the polygons. The polygons can be provided to a device display for rendering of a three dimensional image of navigation data.

Abstract: A method and a device for controlling the level of a pulsed high-frequency signal amplify or respectively attenuate an un-pulsed high-frequency signal with an amplification or attenuation element adjustable with regard to its amplification or attenuation factor. A pulsed high-frequency signal is generated by a pulse modulator controlled by a pulse signal from the un-pulsed high-frequency signal. At the output of the pulse modulator, a signal level of the pulsed high-frequency signal is measured by a high-frequency detector. The amplification or attenuation factor of the amplification or attenuation element is adjusted with a level controller controlled by the measured signal level. To control the level controller, the measured signal level of the pulsed high-frequency signal is linked to the measured signal level of the pulse signal.

Abstract: A radar system includes an arithmetic processing unit, which calculates the second derivative of the intensity of a reflected wave and determines whether a target is an upper structure or a vehicle, based on the second derivative. Alternatively, the arithmetic processing unit decomposes the waveform of the intensity of the reflected wave into frequency components and determines whether the target is an upper structure or a vehicle, based on the intensity of a predetermined frequency component.

Abstract: A method and apparatus for controlling a height of an agricultural equipment component is provided. An average crop height is determined. In one embodiment, the agricultural equipment component is controlled to maintain a predetermined distance from a current top of crop level. If a current top of crop level cannot be determined, a virtual top of crop level is calculated using the average crop height value. The agricultural equipment component is controlled to maintain a predetermined distance from the virtual top of crop level. In another embodiment, the agricultural equipment component is controlled to maintain a predetermined distance from current ground level. If a current ground level cannot be determined, a virtual ground level is calculated using the average crop height value. The agricultural equipment component is controlled to maintain a predetermined distance from said virtual ground level. An ultrasonic sensor is also provided.

Abstract: An exemplary embodiment relates to an aircraft system for detecting wires. The system includes a processor configured to actively sense a presence of a first object and a second object. The processor determines a location of the first object and the second object. The processor determines a potential location of a wire between the first object and the second object. The processor actively senses the wire by providing electromagnetic energy to the potential location.

Abstract: The invention relates to a method for estimating an object motion characteristic from a radar signal. The method comprises the step of receiving radar data of an object from a multiple beam radar system. Further, the method comprises the steps of associating radar data with estimated height and/or cross-range information of object parts causing the corresponding radar data and fitting an object model with radar data being associated with a selected estimated height and/or cross-range information interval. The method also comprises the step of determining an object motion characteristic from the fitted object model.

Abstract: The invention encompasses a system and method for monitoring a power line. In certain embodiments, a system emits a series of signals that allow for analytic analysis of a power line. For example, by taking multiple signal readings, it is possible to detect an average height reading of a power line and observe long-term trends in the time delay from signal emission to reception of an echo-signal. This allows for accurate measurement of various physical parameters of a power line, for example, the height of the power line above the ground.

Abstract: An apparatus for estimating a height at which a target flies over a reflective surface. The apparatus includes means for emitting a signal, and means for receiving signals, including the emitted signal after it has been echoed by the target. The apparatus also includes a height estimator configured to estimate the height by utilizing a direct signal coming directly from the target after the emitted signal has been echoed by the target, an indirect signal coming indirectly from the target after the emitted signal has been echoed by the target and has been reflected by the surface, and reflection parameters including at least one of an amplitude of a reflection coefficient of the surface and a phase difference between the direct signal and the indirect signal. The height estimator comprises a particle filter configured to dynamically estimate the reflection parameters.

Abstract: Present novel and non-trivial systems and methods for generating aircraft height data are disclosed. A processor is configured to receive both first data comprised of radar-based reflection data of a stationary reference point based upon a horizontal distance between the geographic position of an aircraft and the geographic position of the stationary reference point (e.g., landing threshold point) and second data comprised of internally sourced vertical travel data more frequently than the first data. From the first data and second data, an instant vertical distance above the stationary reference point is determined by updating the first data with the second data. Then, instant height data representative of the instant vertical distance above the stationary reference point is generated. Provided with the instant height data, a presentation system comprised of display unit, aural alert unit and/or a tactile alert unit may present the instant vertical distance to the pilot.

Abstract: A ground based avian radar receive antenna is implemented using a vertically oriented offset parabolic cylindrical antenna. The desired azimuth beamwidth is determined by the width of the parabolic cylinder reflector surface and the desired elevation beamwidth by the height of the parabolic cylinder reflector surface. A vertical array of antenna elements is mounted along the vertical focal line to provide electronic scanning in elevation. Low sidelobe levels are obtained using tapered antenna element illumination. Low cost modular construction with high reflector accuracy is obtained by attaching a thin metal reflector to thin ribs machined or stamped in the shape of the parabolic cylinder reflector surface. The antenna is enclosed in a radome and mechanically rotated 360 degrees in azimuth.

Abstract: A obstacle detection system comprises a transmission antenna operable to radiate a radio frequency (RF) signal and a transmitter operable to control transmission of the RF signal from the antenna. The obstacle detection system also comprises a receiver antenna operable to receive a reflection of the RF signal; and processing circuitry operable to analyze a plurality of characteristics of a radar cross section (RCS) of the received reflection to identify an obstacle and one or more physical attributes of the obstacle.

Abstract: The invention relates to a method for managing the flight of an aircraft flying along a trajectory and being subject to an absolute time constraint (on a downstream point) or relative time constraint (spacing with respect to a downstream aircraft), the said aircraft comprising a flight management system calculating a temporal discrepancy to the said time constraint, wherein the said method includes the following steps: the calculation of a distance on the basis of the temporal discrepancy, the modification of the trajectory: if the temporal discrepancy to the time constraint corresponds to an advance, the lengthening of the trajectory by the distance; if the temporal discrepancy to the time constraint corresponds to a delay, the shortening of the trajectory by the distance.

Abstract: A remote control system includes a receiver equipped in a device and a remote controller. The receiver includes a positioning unit to acquire current position information of the receiver. The controller includes a positioning unit to acquire current position information of the remote controller. The current position information of the remote controller and a control signal is transmitted to the receiver. The receiver further includes a processor to control the device to execute an operation corresponding to the control signal based on the current position information of the remote controller and the receiver.

Abstract: A radar system (44) for a vehicle (42) includes a transmit unit (56) and a receive unit (58). The transmit unit (56) includes a single beam antenna (72) for output of a radar signal (74) into a target zone (46). The receive unit (58) includes a single beam antenna (76) for receiving a direct receive signal (78) and an indirect receive signal (80). The receive signals (78, 80) are reflections of the radar signal (74) from an object (34, 36) in the target zone (46). The indirect receive signal (80) is reflected off the object (34, 36) toward a reflective panel (54) of the vehicle (42), and the indirect receive signal (80) is reflected off the reflective panel (54) for receipt at the receive antenna (76). The receive signals (78, 80) are summed to produce a detection signal (81) indicating presence of the object (34, 36) in the target zone (46).

Abstract: A radar system includes an arithmetic processing unit, which sends a warning command to a warning device when a local minimum point of the intensity of the reflected wave from a target within a predetermined detection range is detected. By determining whether it is necessary to send a warning command based on whether there is a local minimum point of the intensity within the detection range, it is made possible to determine whether it is necessary to send a warning command more quickly as compared to the conventional system.

Abstract: Device and a method for locating a mobile object approaching a surface reflecting electromagnetic waves. The location device includes an emission antenna and a reception antenna. The emission antenna has one or more emission positions emitting a detection signal toward the mobile object. The reception antenna has at least one column of one or more reception positions, receiving a signal transmitted by the mobile object. An emission of the detection signal is activated on each emission position. An emission position that produces a detection by the reception antenna, of the signal of maximum energy transmitted by the mobile object, is selected to track the mobile object. One or more signals of maximum energy, received by one or more reception positions, are used to angularly locate the mobile object. The invention can be used to determine the position of an aircraft in the final landing phase for a guidance device.

Abstract: A radar device includes: a receive antenna having a plurality of element antennas disposed in the left-right direction such that at least some of the plurality of element antennas is shifted in the up-down direction from the others; and a position detecting ECU. The position detecting ECU Includes: a first position detecting section, which detects a position of an object in the up-down direction, based on a phase difference between the respective reception signals received by the plurality of element antennas; and a first position correcting section which corrects the position in the up-down direction, based on the history of the position in the up-down direction, and obtains a first corrected position which is a position in the up-down direction after the correction.

Abstract: A method and apparatus of determining a wave height directional spectrum of an ocean wave field using the intermediate-frequency (IF) signal from marine radars with a rotating antenna, using either a fully coherent or a standard non-coherent transmitter/receiver modified for coherent-on-receive use. The method may include receiving the IF radar ocean surface echo signal for a series of transmit pulses, at a sequence of azimuthal antenna positions, and a number of antenna rotations covering several minutes, then generating a matrix of complex IF signal samples from these, deriving phases for each sample, generating the difference in phase for consecutive azimuths, then Doppler shifts, and finally radial velocities.

Abstract: Systems and methods for obtaining target elevation information are disclosed. The systems and methods use multiple vertical transmitters and one or more receivers to infer changes in the elevation plane and the height of objects. Changes in elevation and heights of objects are inferred from path length differences between the transmitters and a particular backscattering point. Using known geometric information regarding the configuration of the transmitters, propagation time differences can be estimated via time delay estimation methods in either the time or frequency domain. Appropriate modulation schemes are used such that the multiple signals transmitted are separable upon reception.

Abstract: A target object information estimating device embodied by an electronically agile radar sensor is mounted in a moving vehicle. The device has a unit outputting a radar wave every measuring period, receiving radar waves reflected from a target object through different transmission paths and calculating a distance to the object in each measuring period to detect the object, a unit tracking the object in a tracking term of measuring periods, a unit setting the distance changed with time as a null distance each time electric power of the received waves is reduced to a minimal value, and a unit producing an actual pattern of null points corresponding to the null distances, collating the actual pattern with modeled patterns corresponding to various heights and estimates the height of the object from the collation result as information about the object.

Abstract: The invention relates to a three-dimensional target tracking method comprising acquiring a first track generated by a first target location system having a first coverage area, said first track comprising a first position of a first target at a given time in a first relative reference system of the first target location system; acquiring a second track generated by a second target location system having a second coverage area partially overlapping the first coverage area in a coverage region shared by the two target location systems, said second track comprising a second position of a second target at the given time in a second relative reference system of the second target location system; and carrying out a correlation test and, if a same height is determined for the first and second targets, detecting that the first and second targets represent a same single target present in the shared coverage region.

Abstract: Disclosure is a forward-looking 3D imaging radar, comprising: a transmitting unit which generates RF signals to be radiated for observing object in front of the radar; a transmitting antenna which radiates the RF signal generated by the transmitting unit; a receiving antenna which receives signals radiated from the transmitting antenna and reflected by the object in front of the radar; a receiving unit which mixes the signal received by the receiving antenna and the branched signal from the transmitting unit, and converts the signal to digital signal; and a signal processor which controls the operations of the transmitting unit and receiving unit, sends command to the transmitting unit to generate RF signals, receives the digitally converted signal from the receiving unit and extracts phase information of the object in front of the radar, and generates 3D radar image by producing altitude information based on the principle of interferometer.

Abstract: According to embodiments, there is provided a radar apparatus including: a transmission antenna configured to transmit an electromagnetic wave; a reception antenna configured to receive an electromagnetic wave when the transmitted electromagnetic wave has been reflected by an object; a reception wave acquisition section configured to acquire the received electromagnetic wave at specific intervals in time; a reception power calculator configured to compute the power of the received electromagnetic wave as a function of the acquisition time number by the reception wave acquisition section; a representative point extractor configured to extract plural representative points from the function; and a determination section configured to determine whether or not the object is an overhead object positioned higher than the optical axis of the receiving antenna based on the representative points.

Abstract: The present invention relates to a method for determining the position notably the elevation of a target flying at very low altitude. An electromagnetic detection system extracts the measurement of the elevation on the basis of the amplitude of the interference signal produced by a signal emitted directly by the target and by a signal emitted by the target towards the ground then reflected by the ground towards the radar. Embodiments of the invention can notably be used within the framework of the guidance of drones in the final landing phase.

Abstract: A system, method, and/or apparatus for remote measurement of terrestrial biomass contained in vegetative elements, such as large tree boles or trunks present in an area of interest, are provided. The method includes providing an airborne VHF radar system in combination with a LiDAR system, overflying the area of interest while directing energy toward the area of interest, using the VHF radar system to collect backscatter data from the trees as a function of incidence angle and frequency, and determining a magnitude of the biomass from the backscatter data and data from the laser radar system for each radar resolution cell. A biomass map is generated showing the magnitude of the biomass of the vegetative elements as a function of location on the map by using each resolution cell as a unique location thereon. In certain preferred embodiments, a single frequency is used with a linear array antenna.

Abstract: A target object information estimating device embodied by an electronically agile radar sensor is mounted in a moving vehicle. The device has a unit outputting a radar wave every measuring period, receiving radar waves reflected from a target object through different transmission paths and calculating a distance to the object in each measuring period to detect the object, a unit tracking the object in a tracking term of measuring periods, a unit setting the distance changed with time as a null distance each time electric power of the received waves is reduced to a minimal value, and a unit producing an actual pattern of null points corresponding to the null distances, collating the actual pattern with modeled patterns corresponding to various heights and estimates the height of the object from the collation result as information about the object.

Abstract: A radar system comprises a transmitter antenna configured to transmit a radio frequency (RF) signal, a first receiver antenna, and a second receiver antenna. Each of the first and second receiver antennas are configured to receive a reflection of the RF signal, wherein the first and second receiver antennas are synchronized and separated by a vertical distance. The radar system also comprises radar processing circuitry configured to control transmission of the RF signal from the transmitter antenna and to determine an elevation of an object reflecting the RF signal based on the phase difference between the reflected RF signal received by the first receiver antenna and the reflected RF signal received by the second receiver antenna; wherein the transmit antenna, first receiver antenna, and second receiver antenna are operable to continuously rotate 360 degrees along an azimuth angle without rotating along an elevation angle.

Abstract: A height-finding 3D avian radar comprises an azimuthally scanning radar system with means of varying the elevation pointing angle of the antenna. The elevation angle can be varied by employing either an antenna with multiple beams, or an elevation scanner, or two radars pointed at different elevations. Heights of birds are determined by analyzing the received echo returns from detected bird targets illuminated with the different elevation pointing angles.

Abstract: A method and apparatus of determining a wave height directional spectrum of an ocean wave field using the intermediate-frequency (IF) signal from marine radars with a rotating antenna, using either a fully coherent or a standard non-coherent transmitter/receiver modified for coherent-on-receive use. The method may include receiving the IF radar ocean surface echo signal for a series of transmit pulses, at a sequence of azimuthal antenna positions, and a number of antenna rotations covering several minutes, then generating a matrix of complex IF signal samples from these, deriving phases for each sample, generating the difference in phase for consecutive azimuths, then Doppler shifts, and finally radial velocities.

Abstract: A narrowband radar arrangement having a radar transmitter and a radar receiver mounted above a targeted water surface to monitor and determine a sea state of the targeted water surface. Fixed frequency signals are transmitted by the transmitter and received by the receiver, via a direct path and via a forward scattered path off the targeted water surface. An interference pattern of interfering direct path signals and forward scattered signals is used to determine an instantaneous height of the water surface and also to determine the sea state of the targeted water surface.

Abstract: A navigation solution of a navigation system with a Terrain Navigation Module is determined by a procedure including determining a supported position solution and the relative covered path between two height measurements, ascertaining a quality of each active supported position from each active supported position by way of a first quality function, and creating a search area and predetermined positions for each position inside the search area and each relatively stored covered path. The procedure further includes ascertaining a quality of each relatively stored terrain height measurement, and a quality of each reference height, and determining the quality of the position support by a function of all minimum probabilities of all used positions in the search area and supporting the navigation solution ascertained in the Strap Down Module by the navigation filter with the aid of the determined position support and the determined quality of the position support.

Abstract: A broadband radar arrangement having a radar transmitter and a radar receiver mounted above a targeted water surface to monitor and determine a sea state of the targeted water surface. Spectrally spaced signals are transmitted by the transmitter and received by the receiver, via a direct path and via a forward scattered path off the targeted water surface. An interference pattern of interfering direct path signals and forward scattered signals is used to determine an instantaneous height of the water surface and also to determine the sea state of the targeted water surface.

Abstract: A method implementable in a weather-radar system of an aircraft, the weather-radar system configured to generate to a display device, in response to radar return information indicating reflectivity levels below a predetermined reflectivity threshold, an image in a first presentation format. The method includes determining if the altitude of the aircraft is above a predetermined threshold altitude, and, if the altitude of the aircraft is above the threshold altitude, displaying, in response to radar return information indicating reflectivity levels below the predetermined reflectivity threshold, the image in a second presentation format different from the first presentation format.

Abstract: A circuit for a display used on an aircraft causes the display to display a composite terrain image. The composite terrain image can be formed from first terrain data from a terrain database and second terrain data from a radar system. A display control circuit can generate a display signal for the composite terrain image. The display signal is received by the display. The composite terrain image can be viewed by a pilot.

Abstract: A height-finding 3D avian radar comprises an azimuthally scanning radar system with means of varying the elevation pointing angle of the antenna. The elevation angle can be varied by employing either an antenna with multiple beams, or an elevation scanner, or two radars pointed at different elevations. Heights of birds are determined by analyzing the received echo returns from detected bird targets illuminated with the different elevation pointing angles.