Abstract: An adaptive inductive ballast is provided with the capability to communicate with a remote device powered by the ballast. To improve the operation of the ballast, the ballast changes its operating characteristics based upon information received from the remote device. Further, the ballast may provide a path for the remote device to communicate with device other than the adaptive inductive ballast.

Abstract: Various techniques are disclosed for providing a radar system. In one example, such a radar system includes a radar unit adapted to broadcast radar signals and receive return signals in response thereto. The radar unit includes a waveform generator adapted to provide the radar signals, a power amplifier adapted to amplify the radar signals for broadcast, an antenna adapted to broadcast the radar signals and receive the return signals, a signal directing device adapted to selectively direct the radar signals to the antenna and the return signals from the antenna, and a transmission interface adapted to transmit radar data based on the return signals from the radar unit to a base station. Other examples of radar systems and related methods are also provided.

Abstract: This disclosure provides a navigation aid device that includes a calculation time setting module for setting two or more calculation points of time for calculating trial information, a ship-concerned information acquisition module for acquiring ship-concerned information including a position of a ship concerned at every predetermined ship-concerned information acquisition time, a ship-concerned trial information calculating module for calculating ship-concerned trial information including the position of the ship concerned at each calculation point of time based on the ship-concerned information acquired at the newest information acquisition time with respect to the calculation point of time.

Abstract: This disclosure provides an image processing device, which includes an actual trail image memory for storing an actual trail data group indicating absolute changes in position of a target object detected by echo signals obtained corresponding to detection signals transmitted while changing an azimuth direction of the transmission, and a moving target object determination processing module for determining whether the target object detected with the detection signals is a moving target object based on the actual trail data group.

Abstract: A real-time radar surveillance system comprises at least one land-based non-coherent radar sensor apparatus adapted for detecting maneuvering targets and targets of small or low radar cross-section. The radar sensor apparatus includes a marine radar device, a digitizer connected to the marine radar device for receiving therefrom samples of radar video echo signals, and computer programmed to implement a software-configurable radar processor generating target data including detection data and track data, the computer being connectable to a computer network including a database. The processor is figured to transmit at least a portion of the target data over the network to the database, the database being accessible via the network by at least one user application that receives target data from the database, the user application providing a user interface for at least one user of the system.

Abstract: This disclosure provides a navigation assisting device, which includes a TT information acquiring module for acquiring target object data by performing target tracking based on an echo received by a radar antenna, an AIS information acquiring module for acquiring target object data based on a Universal Shipborne Automatic Identification System, a maximum-number-of-output-data determination module for determining a maximum number of output data that is the number of target object data that is outputable while the radar antenna revolves once, a priority determination module for performing a priority determination according to a predetermined rule, for the target object data acquired by the TT information acquiring module and the target object data acquired by the AIS information acquiring module, and an output control module for outputting the target object data fewer than the maximum number of output data according to the priorities while the radar antenna revolves once.

Abstract: An apparatus or a method for preventing radio-frequency (RF) interferences between rotating antennas. For example, the invention is particularly applicable to radar and communication systems on board naval ships.

Abstract: A high resolution, low power marine radar for use in applications such as the newly mandated barge/river radars that are to be used in very confined spaces such as canals. An example radar system includes frequency-modulated/continuous-wave (FM/CW) radar that uses very low transmitter power (a fraction of a watt) and has an exceptionally short sensing range of a few feet or even inches if needed.

Abstract: A target in a mobile platform's obstructed zone can be cleared from the obstructed zone and engaged in the most time-efficient manner by determining the direction of the maneuver that would require the shortest amount of time to clear the target and then maneuvering the mobile platform in that direction.

Abstract: The present invention can find the exact location anywhere in the nautical world (latitude/longitude coordinates) by correlating or matching radar returns with maps produced by a digital nautical chart called a Chart Server, because each pixel location on the Chart Server maps can be traced back to a latitude/longitude coordinate. An obstacle avoidance module called a Chart Server provides digital nautical charts to create a map of the world. To determine the current world location of a vehicle, the invention combines the Chart Server maps with a radar return, which also appears to display prominent features such as coastlines, buoys, piers and the like. These return features from the radar are correlated or matched with features found in the Chart Server maps. The radar then reports its current location inside of its local map, which when translated to the Chart Server map, correlates to a latitude/longitude registration location.

Abstract: There is provided a method for identifying, at the moment of verification, the situation of a threat to a protected ground, airspace and/or sea limits by an approaching ground vehicle, aircraft or sea-going vessel. The method includes an authorized driver/pilot/captain to select first state in which the vehicle, aircraft or sea-going vessel is not considered to present a threat and a second state in which the vehicle, aircraft or sea-going vessel is considered to present a threat. The method further provides entering the first and second PIN codes into a smart card for generating a One Time Indicia (OTI) for each of the PIN codes and disclosing the state associated with each of the first and second OTI codes to at least one control center. Upon the control center receiving an OTI code, the control center obtains positive identification of the driver/pilot/captain and the degree of the threat that the vehicle, aircraft or sea-going vessel presents.

Abstract: Radar return processing systems and methods are operable to process radar information when an installation vehicle is operating in proximity to a surface area of interest. An exemplary embodiment reduces energy of an output pulse emitted from a radar system; receives a plurality of radar returns from a plurality of objects that reflect the reduced energy output pulses emitted from the radar system; determines a surface area of interest based upon at least a current location of the installation vehicle; and filters the radar returns generated by objects that are located outside of the surface area of interest. Optionally, some systems and methods may reduce a sweep range of an antenna from which the reduced energy output pulses are emitted.

Abstract: Methods and systems are disclosed to associate input data with status, location, and technical attributes to arrive at a uniquely identified candidate object by obtaining a set of initial candidate objects based on input data being compared to known technical attributes of uniquely identified objects, obtaining best-known object location and status history for each initial candidate object using previously known location and status information of each initial candidate object, assigning a statistical weight to each initial candidate object based on its maximum calculated speed and speed capabilities of each initial candidate object, generating an association probability of each of the initial candidate objects to the input data to arrive at a set of final candidate objects, and re-evaluating any of the above with data considered to be current that was not used, wherein the set of final candidate objects are uniquely identified candidate objects arrived at with current data.

Abstract: A method for validating positional data in vehicle surveillance applications wherein vehicles transmit positional data indicating their own position to surrounding vehicles using a data link over which a transmission is initiated at a given transmission point in time that is known by all users of the data link. A signal transmitted from a radio source over the data link is received at a receiving unit. The signal carries positional data indicating an alleged position of a vehicle. The distance between the receiving unit and the radio source is estimated based on the time of flight and the propagation velocity of the received signal. The time of flight is determined based on the time elapsed from the transmission point in time of the signal to the time of reception of at least a first part of the signal. A deviation value is determined.

Abstract: A radar apparatus having an integral ARPA function transmits at least two kinds of pulse signals, each of which has different pulselength, according to a specific transmission pattern and receives echoes of the transmitted pulse signal. The radar apparatus includes an echo data generator for generating display echo data for each range scale selected for on-screen presentation by using an echo signal obtained with each transmission pulselength, an ARPA processor for generating a single set of motion-related information on each tracked target to be superimposed on the display echo data by using echo signals obtained with the different pulselengths, a display output synthesizer for superimposing the motion-related information on each tracked target generated by the ARPA processor on the display echo data, and a display unit for displaying a superimposed picture produced by the display output synthesizer.

Abstract: A real-time radar surveillance system comprises at least one land-based non-coherent radar sensor apparatus adapted for detecting maneuvering targets and targets of small or low radar cross-section. The radar sensor apparatus includes a marine radar device, a digitizer connected to the marine radar device for receiving therefrom samples of radar video echo signals, and computer programmed to implement a software-configurable radar processor generating target data including detection data and track data, the computer being connectable to a computer network including a database. The processor is figured to transmit at least a portion of the target data over the network to the database, the database being accessible via the network by at least one user application that receives target data from the database, the user application providing a user interface for at least one user of the system.

Abstract: This disclosure provides a navigation assisting device, which includes a TT information acquiring module for acquiring target object data by performing target tracking based on an echo received by a radar antenna, an AIS information acquiring module for acquiring target object data based on a Universal Shipborne Automatic Identification System, a maximum-number-of-output-data determination module for determining a maximum number of output data that is the number of target object data that is outputable while the radar antenna revolves once, a priority determination module for performing a priority determination according to a predetermined rule, for the target object data acquired by the TT information acquiring module and the target object data acquired by the AIS information acquiring module, and an output control module for outputting the target object data fewer than the maximum number of output data according to the priorities while the radar antenna revolves once.

Abstract: A system for preventing light pollution includes one or more radar units that monitor for vehicles in a volume surrounding or containing one or more obstructions having one or more obstruction lights. A master radar detection processing unit receives sensed radar detection information from the one or more radar units with associated radar signal processing units and determines whether a vehicle is present within the monitored volume. A plurality of obstruction light controller units are interconnected in a network, such as a wireless network. Each obstruction light controller unit turns on an obstruction light when a vehicle enters the monitored volume or a failure condition exists, and turns off the obstruction light when the vehicle has vacated the monitored volume and no failure condition exists. The one or more radar units can transmit sensed radar detection information to a master radar detection processing unit via the network.

Abstract: A radar device is disclosed, which includes an antenna for transmitting an electromagnetic wave and receiving an echo signal from a target object while rotating in a horizontal plane, a display module for displaying the target object so as to correspond the echo signal to a position of the target object with respect to the antenna, a speed calculation module for calculating a relative velocity of the antenna and the target object, and a risk level detection module for detecting a risk level of the target object based on the relative velocity of the target object calculated by the speed calculation module. The speed calculation module calculates the relative velocity of the target object based on a change in phases of at least two of the echo signals received at a different time. The display module controls a display mode of the target object based on the risk level.

Abstract: Methods and apparatuses are described that enable the automatic collection of maritime vessel location information within a global or regional framework by using a minimum network of vessels outfitted with non-intrusive AIS data collection systems. The network of vessels may comprise standard ships operating within their normal commercial or private tasks. By utilizing these non-specially tasked vessels and augmenting the received AIS reports with onboard radar/navigation information, accurate global or regional tracking information can be generated at a centralized location without incurring large costs.

Abstract: Provided is a system and method for route planning and evaluation. The system includes a host object location device operable to provide the location of a host object over the passage of time. A sensor is also provided, operable to sense objects and data from an environment proximate to the host object. A computer is operatively coupled to the location device, the sensor device, a chart library and a display. The computer includes a route generator operable to generate a predicted route of at least one sensed object. The route generator is also operable to generate a planned route of the host object. The planned and predicted routes are displayed to an operator upon the display. In response to a predicted proximate convergence of the host object and at least one sensed object, the convergence signaled to the operator.

Abstract: A radar device includes an antenna, from which a detection signal is transmitted while the antenna being rotated and by which a reflective wave of the transmitted detection signal is received to detect echo data, wherein image data is generated based on the detected echo data, a continuity detecting module for detecting a planer continuity of the currently detected echo data with respect to a pixel concerned in the image data, a behavior data generating module for generating behavior data indicative of a behavior of the echo data for a predetermined number of scans of the past in the pixel concerned based on behavior determination data, and an echo kind determining module for determining a kind of the echo data of the pixel concerned based on the planer continuity and the behavior data.

Abstract: The vessel monitoring system has, in a trial navigation by provisionally setting a value of the speed of the own vessel arbitrarily, a display unit immediately display an Obstacle Zone by Targets (OZT) corresponding to the speed of the own vessel. The vessel monitoring system includes a calculator for calculating an Obstacle Zone by Targets, a display unit for displaying the Obstacle Zone by Targets obtained by the calculation by the calculator, and an integrated controller for processing trial navigation that integrally controls mutually cooperated processing of calculation by the calculator and display by the display unit, in a trial navigation by provisionally setting a value of the speed of the own vessel arbitrarily, so that the calculator calculates an Obstacle Zone by Targets corresponding to the arbitrarily and provisionally set value of the speed of the own vessel, and the display unit displays the result of the calculation.

Abstract: A method and a device are described for acquiring driving data of a vehicle. Moreover, a computer program and a computer program product are put forward for carrying out the method. In the method described, a three-dimensional, kinematic vehicle model is calculated, including linear-motion-dynamics signals and lateral-motion-dynamics signals. This model can be utilized for reconstructing the vehicle movement.

Abstract: The automatic vehicle braking device is equipped with a braking force control processing portion which, based on the judgment result of a collision judgment processing portion and the judgment result of a steering avoidance judgment processing portion, imparts a turning property in a direction of head-on collision to the vehicle when the lateral position of the obstacle with respect to a travel route curve is large in a condition in which the driver is unconscious of a high possibility of collision between the vehicle and the obstacle and has taken no steering avoidance action yet. As a result, it is possible to reduce the speed of the vehicle and, at the same time, mitigate the damage suffered by the vehicle occupants at the time of collision.

Abstract: A method for small-scale fishing boat to avoid ship collision includes the steps of: (1) equipping the small-scale fishing boat with a radar signal receiver for scanning and receiving radar signals transmitted by other ships within the receiving range of the radar signal receiver; (2) using a monitoring computer having a Marine Geographic Information System (Marine GIS) installed thereon to obtain at real time information about the distance, bearings, and etc. of other approaching ships in order to monitor the dynamic conditions of the approaching ships within the fishing boat's operating water area; and (3) actuating a collision warning mechanism based on the intensities of received radar signals when there is more than one approaching ship, so that the small-scale fishing boat can timely receive a collision warning to reduce the risk of collision and maintain safe and smooth voyage on the sea.

Abstract: Marine radar systems and methods for producing low power, high resolution range profile estimates. Non-linear Frequency Modulation (NLFM) pulse compression pulses are frequency stepped to form a low power, wide-bandwidth waveform. Periodically, calibration filters are determined and applied to return signals for correcting non-ideal effects in the radar transmitter and receiver.

Abstract: A car and ship blind spot-free collision avoidance system includes a plurality of image acquiring units and detecting units externally spaced along the car or the ship, an image processing unit, at least one image display unit, and a power supply unit, all being electrically connected to a control unit. The power supply unit supplies power needed by the system to operate normally. The control unit can determine the car or the ship position and moving direction via gear position of a shift lever and turning direction of a steering wheel, and enable real-time images shot by the image acquiring units corresponding to that position or direction to be processed by the image processing unit and then synchronously displayed on a split screen of the image display unit, so as to eliminate blind spots in driving the car or steering the ship and minimize collision and other accidents.

Abstract: A ship traffic control apparatus includes a location recognizer for measuring a location coordinate of a ship by using a satellite location-based service; a ship identifier/location coordinate manager for storing the location coordinate as coordinate information corresponding to a ship identifier; an accident processing unit for providing an accident information when an accident occurs; and an operation controller for forming location information by mapping between the coordinate information and navigation information, transmitting the location information to other ships or a control system in a prescribed cycle through a radio communication unit, and transmitting accident occurrence information including the accident information and the location information to other ships or the control system.

Abstract: The vessel monitoring system has, in a trial navigation by provisionally setting a value of the speed of the own vessel arbitrarily, a display unit immediately display an Obstacle Zone by Targets (OZT) corresponding to the speed of the own vessel. The vessel monitoring system includes a calculator for calculating an Obstacle Zone by Targets, a display unit for displaying the Obstacle Zone by Targets obtained by the calculation by the calculator, and an integrated controller for processing trial navigation that integrally controls mutually cooperated processing of calculation by the calculator and display by the display unit, in a trial navigation by provisionally setting a value of the speed of the own vessel arbitrarily, so that the calculator calculates an Obstacle Zone by Targets corresponding to the arbitrarily and provisionally set value of the speed of the own vessel, and the display unit displays the result of the calculation.

Abstract: A method for small-scale fishing boat to avoid ship collision includes the steps of: (1) equipping the small-scale fishing boat with a radar signal receiver for scanning and receiving radar signals transmitted by other ships within the receiving range of the radar signal receiver; (2) using a monitoring computer having a Marine Geographic Information System (Marine GIS) installed thereon to obtain at real time information about the distance, bearings, and etc. of other approaching ships in order to monitor the dynamic conditions of the approaching ships within the fishing boat's operating water area; and (3) actuating a collision warning mechanism based on the intensities of received radar signals when there is more than one approaching ship, so that the small-scale fishing boat can timely receive a collision warning to reduce the risk of collision and maintain safe and smooth voyage on the sea.

Abstract: A system for harvesting business intelligence from maritime communications uses AIS signals as the source of information regarding the position and heading of vessels. The system builds and maintains a data base of location information of vessels within one or more defined geographic areas over time. The system further includes definitions of points of interest and can use the information from the AIS signals to identify and store events associated with the points of information.

Abstract: A radar controlled automatic target illumination system for marine and other moving vessels. A radar system operably connected to the vessel produces an electronic signal corresponding to an azimuth of a target relative to, and in proximity to the vessel. An array of lights are connected to the vessel, each light being aimed outwardly in a different lighting sector, the sectors being adjacent one to another around the vessel, each of said lights, when automatically activated, illuminating one lighting sector. An electronic processor is operably connected between the radar system and the array of lights for the automatic selective activation of one or more of the lights to illuminate the target within a corresponding lighting sector which the radar system has identified.

Abstract: Method and apparatus to track a contact using a sensor in a two-dimensional radar system, determine a closest point of approach (CPA) for the contact, determine a time to closest point of approach (TCPA) for the contact, and estimate an altitude for the contact from the closest point of approach (CPA) and a cross line of sight distance during the time to closest point of approach (TCPA).

Abstract: Method and apparatus to track a contact using a sensor in a two-dimensional radar system, determine a closest point of approach (CPA) for the contact, determine a time to closest point of approach (TCPA) for the contact, and estimate an altitude for the contact from the closest point of approach (CPA) and a cross line of sight distance during the time to closest point of approach (TCPA).

Abstract: Driver assistance system of a land or water vehicle that encompasses a long-range radar apparatus for the detection of distant objects and at least one short-range detection apparatus for the detection of objects in the vehicle's close proximity. The system further includes an operation control apparatus for control of operation at least of the long-range radar apparatus depending on a motion state of the land or water vehicle. The operation control apparatus is configured to deactivate the long-range radar apparatus at least at standstill of the land or water vehicle or switch it to an essentially powerless standby mode, while keeping the short-range detection apparatus activated.

Abstract: A method for determining the relative position between two or more objects in a marine environment, including waterways, of which at least one object can be maneuvered relative to one or more other objects. At least one interrogator is arranged on one or more of the objects and sends a radio wave signal to at least one transponder arranged on one or more of the other objects. The novel method is the use of a FMCW radar in the interrogator, the use of the transponders for including identity tags into the signals to be reflected to the interrogator, and attitude determination. A system for this determination is also described.

Abstract: This invention allows personnel located on two different structures, such as two ships, to continually monitor the separation distance between the two structures, with all of the necessary equipment being located on only one of the structures. This is accomplished using a laser range finder, or other range sensor, to continually measure separation distance and send it electronically to various displays. The displays are positioned and sized such that all involved personnel can view the continually updating separation distances. The invention incorporates displays large enough to be viewed ship-to-ship in direct sunlight, in addition to smaller displays. The displays are dimmable or backlit for night viewing and include a safety feature that turns them off when communication is lost with any range sensor. A strobe on the display helps personnel find where the display has been positioned, such as on a ships gunwale or hand railing.

Abstract: An instrumented navigation system for aiding a towboat and barge configuration in the entry and traversal of a lock located on a waterway or for navigation around other structures, such as bridge piers or docks. The system consists of wirelessly linked computers on the towboat and the lock which display navigational charts showing the position of the tows as they approach and enter the locks. The computers are also linked to sensors which send information, such as the speed and position of the tows, to the computers for display.

Abstract: A high-frequency oscillator that can tune oscillation characteristics is provided. A high-frequency oscillator includes a Gunn diode serving as a high-frequency oscillation element that generates high-frequency signals, a resonator connected to the Gunn diode, a varactor diode serving as a variable-capacitance element that is disposed on the resonator and changes a resonance frequency, and a bias supply circuit that is connected to the varactor diode and supplies a bias voltage applied in order to change a capacitance. The bias supply circuit includes a trimmable chip resistor serving as a pre-set variable resistor that regulates a bias voltage applied to the varactor diode. By regulating the resistance value of the trimmable chip resistor, it is possible to control the capacitance value of the varactor diode and tune oscillation characteristics to a desired state.

Abstract: A vehicle positioning and tracking radar system includes a rotating antenna with a pair of spatially separated transmit feeds for simultaneously transmitting a pair of frequency-modulated continuous-wave (FMCW) electromagnetic signals having a first polarisation and a pair of spatially separated receive feeds for receiving an electromagnetic signal having a second polarisation, wherein the first and second polarisations are different from one another, such that the transmit feed and receive feed at the rotating antenna are isolated from each other; and a coded modulated transponder receives transmit signals from the rotating antenna with the first polarization and transmits a receive signal to the rotating antenna with the second polarization.

Abstract: In an exemplary embodiment, an augmented reality system for traffic control combines data from a plurality of sensors to display, in real time, information about traffic control objects, such as airplanes. The sensors collect data, such as infrared, ultraviolet, and acoustic data. The collected data is weather-independent due to the combination of different sensors. The traffic control objects and their associated data are then displayed visually to the controller regardless of external viewing conditions. The system also responds to the controller's physical gestures or voice commands to select a particular traffic control object for close-up observation or to open a communication channel with the particular traffic control object.

Abstract: An automation and platform management system for navel vessels configured to be operated from a multimedia information and operation control center. This automation and management system has a system for monitoring and commanding the ship, a system for navigating the ship, a system for coordinating weapons deployment, a system for handling the external and internal radio communications, a system for controlling and handling the information distribution, a system for power generation and distribution (power management monitoring), and a system for monitoring ship operations. To be able further to reduce the number of crewmembers of a ship equipped with the automation and management system, the automation and management system further has a system for automated ship damage control and/or an integrated onboard information and data network (2) and/or an integrated system for monitoring and control of a COPAW drive of the ship.

Abstract: An audio communications control system operates between multiple voice communications systems and a single headset worn by an operator accessing the multiple communications systems via voice transmission. The single headset includes a left speaker, a right speaker, and a microphone. The audio interface provides an electrical connection and operation with each of the voice communications systems, even though each may operate with differing equipment and signal processing. The audio interface switches discrete voice communications signals and routes them to one of the left speaker, the right speaker, and conversely from the microphone of the headset to any of selected systems.

Abstract: A method for transmitting environmental conditions information, which includes receiving at least some environmental conditions information, scaling the received information such that a scaled environmental conditions value is determined for a particular vehicle, receiving an environmental conditions threshold value, comparing the scaled value to the received threshold value, determining whether the scaled value is greater than the received threshold value, and transmitting, if the scaled value is greater than the received threshold value, at least some of the information.

Abstract: A method of data sensor validation is disclosed. The method comprises the steps of pre-processing data sensor from each sensor from a plurality of sensors for at least segmenting the data sensors into a plurality of groups, each group for grouping sensors for sensing highly relevant data one to another; providing the pre-processed data sensor to a correlation processor, the correlation processor for determining from pre-processed data sensor, pre-processed data that is other than correlated, the determination made in dependence upon redundant pre-processed data other than pre-processed data from two sensors for sensing an identical parameter; and, when pre-processed data that is other than correlated is detected, providing an indication to an operator that the sensor data is other than correlated.

Abstract: An auto-docking system has been provided that can automatically dock a ship. The auto-docking system provides a close in radar system and a secondary propulsion system that is under control of a docking processor.

Abstract: A system containing a navigational marker, the navigational marker having the ability to reflect radar in such a manner that the navigational marker is identified. In one embodiment, a polarized radar-reflective material is affixed to the navigational marker. A radar signal is reflected by the polarized radar-reflective material, causing the reflected radar signal to be polarized. The reflected radar signal is received and the navigational marker is identified. The radar system contains a detector/decoder capable of distinguishing the type of navigational marker based on the reflected radar signal. The detector/decoder relays information about the navigational marker to a display. In another embodiment, a navigational marker contains a radio responder. When a radar signal illuminates the navigational marker, the radio responder transmits a signal containing encoded data. A receiver detects the signal from the responder and decodes the encoded data. The decoded data is relayed to a display.

Abstract: A docking information system disposed on a ship provides navigational information to the operator of the ship. The system includes a short range radar system and a display to provide a range between the ship and a dock or an obstacle and, optionally, a relative velocity between the ship and the dock or the obstacle.

Abstract: A collision avoidance system mountable on an aircraft for providing to the pilot of that aircraft an early warning of the presence of another nearby threat aircraft within the surrounding air space. The system operates autonomously from that aircraft and does not require the presence of any matched system on board the threat aircraft. The system includes an omni-directional L-band microwave antenna formed by a dielectric sphere cut into eight equal “orange wedge” sectors covering eight distinct beam patterns. Eight L-band microwave signals are transmitted simultaneously from all eight dielectric sectors to provide a sphere of detection around the aircraft. The sectors also act as receivers for detecting a microwave signal reflected back from the threat aircraft, and indicating means provides information to the pilot regarding the direction, closeness and rate of closure of the threat aircraft.