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 method of imaging a moving object, including the steps of acquiring radar data reflected by the moving object, determining a motion state of the moving object; and generating a three-dimensional representation of the moving object based on the determined motion state, is disclosed. The motion state may be a complete solution of translational and rotational motion determined based on at least one of the inertia tensor components of the moving object, or solutions of Euler's torque-free equations of motions. The three-dimensional representation may be generated by reconstructing static patterns of the moving object based on estimated initial translational and rotational conditions of the object. A system for imaging the moving object according to this method is also disclosed.

Abstract: A scannerless 3-D imaging apparatus is disclosed which utilizes an amplitude modulated cw light source to illuminate a field of view containing a target of interest. Backscattered light from the target is passed through one or more loss modulators which are modulated at the same frequency as the light source, but with a phase delay ? which can be fixed or variable. The backscattered light is demodulated by the loss modulator and detected with a CCD, CMOS or focal plane array (FPA) detector to construct a 3-D image of the target. The scannerless 3-D imaging apparatus, which can operate in the eye-safe wavelength region 1.4-1.7 ?m and which can be constructed as a flash LADAR, has applications for vehicle collision avoidance, autonomous rendezvous and docking, robotic vision, industrial inspection and measurement, 3-D cameras, and facial recognition.

Abstract: Disclosed is a method for measuring a distance between a distance sensor (5), which is carried on a vehicle, and an object (2). The method includes emitting electromagnetic impulse signals (6) and receiving signals (7), which are reflected by the object. Subsequently the signal propagation time is determined. Pulses (10) received after having been reflected by the object (2) are separated and added together, after which the mean value is formed, and the received pulses are superimposed with a modulation signal (18). Also disclosed is a device suited for carrying out the method.

Abstract: In a chromatic point sensor, distance measurements are based on a distance-indicating subset of intensity profile data, which is selected in a manner that varies with a determined peak position index coordinate (PPIC) of the profile data. The PPIC indexes the position a profile data peak. For profile data having a particular PPIC, the distance-indicating subset of the profile data is selected based on particular index-specific data-limiting parameters that are indexed with that same particular PPIC. In various embodiments, each set of index-specific data-limiting parameters indexed with a particular PPIC characterizes a distance-indicating subset of data that was used during distance calibration operations corresponding to profile data having that PPIC. Distance-indicating subsets of data may be compensated to be similar to a corresponding distance-indicating subset of data that was used during calibration operations, regardless of overall intensity variations and detector bias signal level variations.

Abstract: An aiming telescope has an optical axis and a line of sight. Turrets are provided for adjusting the direction of the line of sight. A range finder is structurally connected with the aiming telescope. The range finder has a light source for emitting an emitted measuring beam. The emitted measuring beam runs outside the aiming telescope. It has a direction coinciding essentially with the direction of the line of sight. A transmission is provided for automatically adjusting the direction of the emitted measuring beam when the direction of the line of sight is adjusted. The light source is pivotably mounted on the aiming telescope. The transmission acts between the aiming telescope and the light source.

Abstract: Propagation time for a target signal path is determined by detecting and processing a plurality of unknown signals received at two locations. A third location is established, such that the propagation time between the third location and one of the two locations is known, and the signal path between the third location and the other of the two locations is the target signal path. The two locations are monitored for any signals that may be detected. Signals received at the two locations are processed to determine which signals have a common source, and of the signals having a common source, the signal having the greatest delay between times of reception at the two locations is selected. The selected signal is used to determine the propagation time between the two locations.

Abstract: The present invention relates to antenna calibration for active phased array antennas. Specifically, the present invention relates to a built in apparatus for autonomous antenna calibration Accordingly, the present invention provides a method of self-calibration of a plurality of calibration antennas comprising the steps of: (i) selecting two calibration antennas to be calibrated that have a common area in range of both calibration antennas; (ii) selecting at least one radiating element within range of the two calibration antennas; (iii) transmitted a known test signal from the one or more selected radiating elements; (iv) measuring a received signal at each of the two calibration antennas; (v) comparing the received signals at each of the two calibration antennas; and (vi) determining a correction coefficient for each calibration antenna based on the received signals at the said calibration antennas.

Abstract: A method of analyzing return signals of successive range cells in a scene using constant false alarm rate adaptive control comprising, for each successive range cell in turn is disclosed mathematically. The return signal is processed mathematically and averaged over a predetermined number of cells near that cell. A first variable factor and the return signal for that cell, to derive a first result. The first variable is adapted depending upon that first result. A second variable factor is derived in accordance with a predetermined relationship between the first and second factors are mathematically processed. The second factor is mathematically processed. The second averaged return signal and the return signal for the cell, to derive a second result. The second result is used as an indication of the presence of an object of interest in the scene.

Abstract: An antenna system and electronic scanning method that employs feed subarray electronic offset beam scanning. The system includes a feed element containing an array of electronic transmitting/receiving elements. The system further includes a reflector for reflecting signals received from the feed element to a target region, and for reflecting signals received from a target region to the feed element. Electronic beam scanning is achieved by activating and deactivating in turn subarrays within the array of transmitting/receiving elements of the feed element.

Abstract: A method and system for locating and positioning using broadcast frequency modulation (FM) signals, is provided. One implementation involves receiving FM stereo signals from three FM stations at one or more receivers, each stereo signal including a modulated 19 KHz FM pilot tone; and determining a geographical position at each receiver based on the phase difference of the demodulated pilot tones in the received FM signals.

Abstract: A shared memory device for a receiver system is disclosed. The receiver system is configured to have a first functional stage and a second functional stage for processing information carried by signals from a first transmitter system and a second transmitter system respectively. The shared memory device has a memory space, allocated to be commonly shared by the first functional stage and the second functional stage, for buffering processing data generated from the first functional stage or the second functional stage.

Abstract: The integrity of operation of a GPS precision aircraft approach and landing system may be compromised by error producing effects of reflected multipath signals. An integrity monitor antenna system as disclosed may utilize both attenuation and shadowing of reflected multipath GPS signals to achieve extreme multipath mitigation of the order of 50 dB suppression. An antenna with a right-hand circular polarization pattern having a sharp cut off at the horizon may provide 30 dB suppression of reflected multipath signals. A signal absorbent ground plane bed of defined dimensions may provide 20 dB attenuation of incident multipath signals. A signal/processor may be employed to derive position error data for integrity monitoring, based upon differentials between a known fixed location and a current GPS-indicated location. Communication of identification of a subset of particular GPS satellites for common usage may also reduce potential error levels.

Abstract: A system and method for estimating the range between two devices performs two or more ranging estimates with subsequent estimates performed using a clock that is offset in phase with respect to a prior estimate. The subsequent estimate allows estimate uncertainties due to a finite clock resolution to be reduced and can yield a range estimate with a higher degree of confidence. In one embodiment, these additional ranging estimates are performed at n/N (for n=1, . . . N?1, with N>1 and a positive integer) clock-period offset introduced in the device. The clock-period offset can be implemented using a number of approaches, and the effect of clock drift in the devices due to relative clock-frequency offset can also be determined. To eliminate the bias due to clock-frequency offset, a system and method to estimate the clock-frequency offset is also presented.

Abstract: A positioning system accurately estimates transmission times of signals from a signal transmitter and measures a position of a receiver on the basis of the transmission times.

Abstract: A method for frequency modulated continuous wave LADAR imaging is provided. The method comprises the steps of generating a chirped laser signal and a constant-frequency laser signal, forming a target laser signal from the chirped laser signal and the constant-frequency laser signal and forming a local oscillator laser signal from the chirped laser signal and the constant-frequency laser signal. The method further comprises delaying or frequency shifting the local oscillator laser signal and directing the target laser signal to a target. The method further comprises combining a returned signal received from the target with the delayed or frequency shifted local oscillator laser signal to form a combined received signal, and capturing the combined received signal with a plurality of image sensors.

Abstract: An antenna assembly for receiving the GPS signals in a global positioning system (GPS) receiver module automatically orients the antenna to better receive the GPS signals. The antenna is oriented by a positioner (e.g., a counterweight) that automatically rotates a frame on which the antenna is mounted. The GPS receiver module may also include multiple antennas oriented in different directions to maintain good reception of the GPS signals in any position. The multiple antennas are oriented in a manner so that the poor reception range an antenna is covered by other antennas. Signals from multiple antennas may be combined or chosen for processing by a GPS processor. Also, multiple GPS receiver modules may be deployed in close proximity so that wireless communication between the GPS receiver modules may be established.

Abstract: Techniques are disclosed that allow for the detection, identification, direction finding, and geolocation of emergency personnel in a given multipath environment. For example, the techniques can be used to detect and identify multiple lines of bearing (LOBs) to an IEEE 802.11 emitter of an emergency responder that is inside a building or otherwise hidden from view. LOBs from multiple vantage points can be used to geolocate and/or track the emergency responder. The resulting geolocation can be plotted on a map display or model of the scene (e.g., building, etc) so the precise position of the emergency responder having the targeted wireless emitter can be known.

Abstract: The present invention provides a global navigation satellite system (GNSS) receiver apparatus, such as a GPS receiver, operable with a host computer system equipped with a real time clock configured to provide a time signal to the GNSS receiver apparatus. The time signal is used to facilitate acquisition of navigation and global timing information through observation of satellite signals. The global timing information is used to adjust the time signal and/or the real time clock to improve subsequent acquisitions of navigation and global timing information.

Abstract: A collision prediction system includes a collision face determining unit that determines a collision face of the own vehicle which is presumed to collide with another vehicle, based on a travelling direction of the other vehicle relative to the own vehicle at an estimated collision time at which a collision is presumed to occur, a collision position estimating unit that estimates a collision position as a position of a potential collision between the own vehicle and the other vehicle, based on the collision face determined by the collision face determining unit, and a collision position correcting unit that corrects the collision position estimated by the collision position estimating unit, based on a preset size of the other vehicle.