Abstract: An interrogation transmission method of a secondary surveillance radar compares prediction angle ranges for transmitting interrogations with a beam-width of an antenna, and transmits the interrogations at every roll-call period if the prediction angle ranges for transmitting interrogations are narrower than the beam-width of the antenna. In contrast, if the prediction angle ranges for transmitting the interrogations are wider than the beam-width of the antenna, the radar respectively sets a period to transmit the interrogations and a period not to transmit the interrogations until responses can be received, and transmits interrogations at every roll-call period after the responses can be received (even if a receiving error or downlink occurs).

Abstract: The present invention applies to the surveillance of, in particular civil, air traffic, and more particularly, to cooperative aircraft ground systems which make it possible to pinpoint in radial distance and in azimuth the aircraft present in a certain volume and to interrogate them. A method and a device which makes it possible to determine a reference value of a response contained in a reception signal of a secondary radar, doing so even in the presence of strong pollution, in particular in the event of nesting between mode S responses.

Abstract: There are provided a differential processing unit which performs differential processing for a Mode S transponder transmission signal, an auto correlation arithmetic operation unit which performs an arithmetic operation of a degree of auto correlation between an increasing change rate and decreasing change rate of a power level in the signal which has been subjected to the differential processing, a pulse regeneration unit which regenerates a pulse based on the degree of auto correlation, which has been obtained by the auto correlation arithmetic operation processing, a pulse phase locked loop unit which performs gate processing and phase locked processing for the regenerated pulse, and a pulse decoding unit which decodes the Mode S transponder transmission signal based on the pulse which has been subjected to the gate processing and the phase locked processing.

Abstract: An apparatus for processing pulses in ATCRBS/Mode S interrogations includes an antenna for receiving a radio frequency interrogation signal. The radio frequency interrogation signal is downconverted by a downconverter to an intermediate frequency signal. The intermediate frequency signal is converted to a digitized interrogation signal by an analog-to-digital converter. A processing unit, coupled to the analog-to-digital converter, detects a pulse peak in the digitized interrogation signal using a moving threshold to locate the peak pulse between a first fixed threshold and a second fixed threshold.

Abstract: An apparatus for processing pulses in ATCRBS/Mode S interrogations includes an antenna for receiving a radio frequency interrogation signal. The radio frequency interrogation signal is downconverted by a downconverter to an intermediate frequency signal. The intermediate frequency signal is converted to a digitized interrogation signal by an analog-to-digital converter. A processing unit, coupled to the analog-to-digital converter, detects a pulse peak in the digitized interrogation signal using a moving threshold to locate the peak pulse between a first fixed threshold and a second fixed threshold.

Abstract: A method and system for using a single transceiver to correlate radar position data with target identification data. Two transceivers, operating in round trip delay mode, can be used to provide two possible positions for a given target when radar coverage is lost or unavailable. Three transceivers can be used to provide actual position of a given target using round trip delay data only.

Abstract: The present invention relates to an avoidance system and method for directing an aircraft away from an exclusion zone. The exclusion zone may be any three dimensional space for example about a building or city. The avoidance system uses a constant signal from a ground based transmitter and an aircraft's receiver which receives and processes the signal and activates the avoidance system by engaging the flight director system or autopilot to steer away from the exclusion zone.

Abstract: This invention is a system and method of locating a target using distributed antenna. The antenna consists of several receiving elements in known locations. At least one of the receiving elements is also a transmitter and transmits an interrogation signal to a target. The return signal from the target is received by a plurality of receiving elements and the target's position is calculated using the time of arrivals of the reply signal and the round trip delay between the transmission of the interrogation signal and the reception of the subsequent reply signal.

Abstract: A method to efficiently implement a reconfigurable electronic radio system (400) including resource assets (402–408, 410–416, 418, 420–426, 428) and a processor (428). The processor (428) generates RF control and switching control signals during each mission segment of an aircraft to create radio function threads through the resource assets (402–408, 410–416, 418, 420–426, 428) to realize the radio functions for that mission segment. The processor (428) may also be coupled to a master processor (440) that sends the processor (428) a radio function set selection signal. The radio function set selection signal identifies the radio function set that the processor (428) will implement through the resource assets (402–408, 410–416, 418, 420–426, 428). The processor (428) performs all signal, data, message, cryptographic and control processing required for the radio function threads being implemented by the resource assets.

Abstract: A secondary surveillance radar system for use in surveillance of an airspace, which reliably achieves surveillance of the airspace even when an aircraft including a mode S transponder and an aircraft including an ATCRBS transponder are both located in the airspace, wherein both of a time interval between time when transmission of an all-call interrogation signal specific for mode S is completed and time when the transmission of an all-call interrogation signal specific for mode A is started and a time interval between time when transmission of the all-call interrogation signal specific for mode S is completed and time when transmission of an all-call interrogation signal specific for mode C is started is varied in units of one all-call time period.

Abstract: A Mode-S transponder is provided for detecting synchronization phase reversal (SPR) signals. The transponder includes a receiver for receiving a Mode-S signal that contains a P6 pulse having a Mode-S data segment and an SPR signal therein. The transponder also includes a phase detector that detects a phase change between first and second states in the received Mode-S signal. The phase detector includes an SPR qualifier that determine whether, following a state change, the Mode-S signal remains at one of the first and second states for at least a predetermined minimum time sufficient to qualify as a detector enable signal.

Abstract: A civil aviation passive coherent location system and method is disclosed. A receiver subsystem receives reference transmissions from an uncontrolled transmitter. The receiver subsystem also receives scattered transmissions originating from the uncontrolled transmitter and scattered by an airborne object. The received transmissions are compared to determine measurement differentials, such a frequency-difference-of-arrival, a time-difference-of-arrival and an angle of arrival. From the measurement differentials, an object state estimate is determined. A previous state estimate may be updated with the determined state estimate. Processing subsystems determine the measurement differentials and state estimates.

Abstract: An apparatus and method for combining the functionality of multiple airborne traffic surveillance systems that operate in the L-band frequency range. The apparatus and method combine the functionality of both a Traffic Alert Collision Avoidance System (TCAS) and a Mode-Select (Mode-S) transponder in an integrated L-band traffic surveillance apparatus having a single processor that is embodied in a single Line Replaceable Unit.

Abstract: Receiving a message including bits corresponding to an identifier, the identifier including a unique address for a aircraft transponder, extracting the unique address from the identifier, comparing the unique address to a set of predetermined addresses, changing selected ones of the identifier bits when the unique address is not one of the set of predetermined addresses, wherein the changing of the identifier bits changes a value of the unique address in the identifier, re-comparing the updated unique address to the set of predetermined addresses and processing the message when the unique address matches one of the set of predetermined addresses.

Abstract: A transponder lock provides allows an aircraft transponder to continue transmitting an alerting code for the duration of an emergency. The transponder lock thereby enables the aircraft transponder to continue to provide crucial information to ground tracking stations. Installation of the transponder lock results in very little aircraft downtime because the transponder lock connects in-line with existing aircraft wiring.

Abstract: A super resolution processor/receiver to discriminate superimposed secondary surveillance radar (Mode S, Mode A/C) replies and squitter that uses frequency-domain analysis to suppress interference between replies. In particular, the processor/receiver uses a spectral super-resolution method to estimate carriers of reply signals (every reply has a carrier that could be slightly different from the others). These frequency analyses, applied with particular timing referring to the signal that effectively carried the information, allow to estimate the information on SSR Mode S/Mode A/C replies.

Abstract: A super resolution processor/receiver to discriminate superimposed secondary surveillance radar (Mode S, Mode A/C) replies and squitter that uses frequency-domain analysis to suppress interference between replies. In particular, the processor/receiver uses a spectral super-resolution method to estimate carriers of reply signals (every reply has a carrier that could be slightly different from the others). These frequency analyses, applied with particular timing referring to the signal that effectively carried the information, allow to estimate the information on SSR Mode S/Mode A/C replies.

Abstract: A ground-based CFIT warning system provides pilots with CFIT alerts. The system is based upon a ground-based tracking system, which provides surveillance of aircraft, such as the AirScene™ multilateration system manufactured by Rannoch Corporation of Alexandria, Va. The system monitors both horizontal and vertical positions of aircraft. When an aircraft has been determined to be operating below safe altitudes, or too close to obstructions, the pilot is provided with a warning. The warning may be delivered via the pilot's voice communications and/or a data link or the like.

Abstract: An algorithm for improved tracking of Air Traffic Control Radar Beacon System transponders is disclosed. The algorithm can be combined with a system that includes an interrogator which transmits an interrogation signal to an associated vehicle transponder at a first frequency, preferably 1030 MHZ in accordance with FAA regulations, and a receiver array which receives the transponder reply signal transmitted by the transponder at a second frequency, preferably 1090 MHZ in accordance with FAA regulations. An angle of arrival processor calculates an angle of the received reply signal, and a position processor calculates the vehicle position based on at least the received angle data.

Abstract: A system and method for measuring and predicting information on the position of approaching aircraft are disclosed. The system features a processor, an interrogating antenna, a receiving antenna, and a data link. The processor schedules interrogations and suppression pulses. Both of the antennas and the data link are in signal communication with the processor. The interrogating antenna transmits interrogations to a plurality of approaching aircraft. At least some of the interrogations include suppression pulses. The receiving antenna comprises at least three fixed, broad azimuth, array elements. The receiving antenna receives replies from each of the plurality of approaching aircraft and communicates the replies to the processor. The processor determines a state for each of the plurality of approaching aircraft based on the replies. The data link communicates information on the state of each of the plurality of approaching aircraft from the processor.

Abstract: A method is provided for controlling transponder replies to Mode-S interrogation signals. The method includes receiving Mode-S signals containing P5 and P6 pulses each having certain amplitudes. Each P6 pulse contains a sync phase reversal (SPR) signal followed by a data segment containing Mode-S data. The P5 pulse is asynchronous with respect to the P6 pulse and is timed to overlay the SPR signal. The method includes, analyzing each P5 and corresponding P6 pulse, identifying the SPR signal correctly in the received Mode-S signals in which the amplitude of the P6 pulse is at least 12 dB greater than the amplitude of the P5 pulse and in no more than 2% of the received Mode-S signals in which the amplitude of the P6 pulse is at least 3 dB less than the amplitude of the P5 pulse, and replying to the Mode-S signals where the SPR signal is correctly identified.

Abstract: A Mode-S transponder is provided for detecting synchronization phase reversal (SPR) signal. The transponder includes a receiver for receiving a Mode-S signal that contains a P6 pulse having a Mode-S data segment and an SPR signal therein. The transponder also includes a phrase detector that detects a phase change between first and second states in the received Mode-S signal. The phase detector includes an SPR qualifier that determine whether, following a state change, the Mode-S signal remains at one of the first and second states for at least a predetermined minimum time sufficient to qualify as a detector enable signal.

Abstract: This invention relates to a robust data fusion procedure of multi-digital surveillance information mounted on an aircraft per se capable of receiving surveillance information of other aircrafts, including traffic information service (TIS), traffic alert and collision avoidance system (TCAS) and automatic dependant surveillance broadcasting (ADSB). The data fusing procedure of the multi-digital surveillance information of this invention is capable of applying data fusion module to provide an effective surveillance data fusion procedure for fusing the data produced by surveillance source (ADSB, TCAS and TIS). The traffic information of the aircraft per se is provided by GNSS while outputting the status information of other aircrafts in the surrounding airspace to the cockpit display traffic information (CDTI) system to enhance airborne security.

Abstract: A surveillance and collision avoidance system provides a presentation of situational awareness information for display that includes a compound symbol for each target spaced at a distance and bearing relative to a host symbol. The target compound symbol includes indicia of (a) whether the target is airborne or on the ground; (b) whether the target is a civil aircraft, a military aircraft identified as a formation member with the host aircraft, or a military aircraft not identified as a formation member with the host aircraft; (c) whether a ground track for the target is unknown, known by passive surveillance, or known by active surveillance; (d) for civil aircraft, whether the target is the subject of no advisory, a traffic advisory, or a resolution advisory; and (e) for a military aircraft, whether the target is the subject of no encroachment advisory, an unintended encroachment advisory, or an intended encroachment advisory. Subsystems selectively use an active or a passive mode of surveillance.

Abstract: A system and method for measuring and predicting information on the position of approaching aircraft are disclosed. The system features a processor, an interrogating antenna, a receiving antenna, and a data link. The processor schedules interrogations and suppression pulses. Both of the antennas and the data link are in signal communication with the processor. The interrogating antenna transmits interrogations to a plurality of approaching aircraft. At least some of the interrogations include suppression pulses. The receiving antenna comprises at least three fixed, broad azimuth, array elements. The receiving antenna receives replies from each of the plurality of approaching aircraft and communicates the replies to the processor. The processor determines a state for each of the plurality of approaching aircraft based on the replies. The data link communicates information on the state of each of the plurality of approaching aircraft from the processor.

Abstract: A method of processing reply signals received in response to an interrogation by a secondary surveillance radar system. The method includes the steps of receiving a reply signal from each of a plurality of targets, and enabling each of a plurality of target mode blocks having a predefined mode to select from the reply signals. The method further includes the step of correlating the selected reply signal to the target mode block that selected same.

Abstract: An aircraft system and method for determining when to attempt acquisition of an intruder for active tracking. A link reliability score associated with the intruder is adjusted based upon the signal strength of transmissions, the frequency of the transmissions, and the number of previous attempts to acquire the intruder for active tracking.

Abstract: A method of processing reply signals received in response to an interrogation by a secondary surveillance radar system. The method includes the steps of receiving a reply signal from each of a plurality of targets, and enabling each of a plurality of target mode blocks having a predefined mode to select from the reply signals. The method further includes the step of correlating the selected reply signal to the target mode block that selected same.

Abstract: A target/track assignment method for a combined radar/ADS surveillance environment uses tandem cycles to help the air traffic control system update the order of system tracks, thereby permitting numerous target reports to be processed in real time.

Abstract: A tracking data fusion method used in a combined radar/ADS surveillance environment defines track states, track types, and track types transition rules to track aircraft. The best available flight services could be provided if the proposed method is used in an air traffic control system.

Abstract: A surveillance transceiver system is provided for receiving extended squitters from Mode S transponders, translating the squitters into ADS-B state vectors in UAT format, and transmitting the ADS-B state vectors using a Universal Access Transceiver (UAT) datalink. The surveillance transceiver system bridges the gap created by differently-equipped aircraft by using multiple datalinks to provide seamless ADS-B surveillance. The module for processing the extender squitters includes a 1090 MHz receiver and a computer processor in communication with the UAT processor for parsing the squitter and composing the ADS-B state vector in UAT format for broadcast.

Abstract: A system and method for displaying target vehicle position that combines the data available from a plurality of surveillance sensors. Data from the plurality of sensors is fused to calculate a composite target position and a projected track for each vehicle within the range of the sensors. The composite data is also used to calculate a boundary of certainty for both the position and the projected track. The position, projected track and the boundaries of certainty for each target vehicle can be displayed on a display screen.

Abstract: Disclosed is a method to determine target azimuth by the use of a radar, especially of the ASR type. The radar sends out a wave of detections by N-pulse bursts. The method comprises at least the following steps in one burst: a step in which the burst is split up into two half bursts, one front burst and one rear burst; a step for the filtering of the half burst to associate an azimuth value &thgr;1 and an amplitude value A1 with the front burst, and an azimuth value &thgr;2 and an amplitude value A2 with the rear burst; a step to obtain the target azimuth Az at a value corresponding to the maximum of a Gaussian curve passing through the points having components (&thgr;1, A1), (&thgr;2, A2). The invention can be applied especially to surveillance radars used, for example, in air traffic management applications.

Abstract: A method and apparatus that permit military aircraft operators to use the civilian Aircraft Addressing and Reporting System (ACARS) technology while ensuring data security.

Abstract: A formation collision avoidance system includes a Traffic Alert and Collision Avoidance System (TCAS) having a passive mode and an active mode. The passive mode enables several members of an aircraft formation to fly without actively interrogating using TCAS while only one or few formation members are actively interrogating. Formation members in passive mode maintain awareness of current air and ground traffic conditions using networked surveillance information provided over a communications link between formation members in active mode and formation members in passive mode. The networked surveillance information includes positional and intent information of current air/ground traffic obtained from ADS-B broadcasts and replies to the actively interrogating members of the formation. The communications link utilizes Station Keeping Equipment (SKE) already existing on certain aircraft.

Abstract: A method for eliminating signals from false targets in a secondary surveillance radar system includes the steps of obtaining plots of radar data for the same target. The range from the radar system to the targets is determined, and the target plot having smallest range of all target plots that indicate reflection of radar signals from the same target is accepted as being a real target. Other target data is rejected as being from a radar reflector. The coordinates of radar reflectors may be stored in a database to form a map of reflectors in the vicinity of the radar.

Abstract: An airport runway incursion detection and warning system for monitoring ground traffic in the vicinity of a runway or taxiway of an airport. The system utilizes a microwave radar transceiver, commonly referred to as a motion detector, connected to a voice annunciator to provide a verbal warning of aircraft or ground vehicle runway incursion. In one embodiment, the microwave transceiver is integrated into a runway lamp and includes a transformer to allow the transceiver to operate from an existing runway lamp power system.

Abstract: An improvement in the present radar/IFF equipment used by the military whereby the transponding equipment, when used in crypto-secure Mode 4, is enabled to reply with its unique coded identification number (Mode 2 reply) after it has made its Mode 4 reply. This is accomplished by adding an AND gate and a delay means to the present equipment. The AND gate is connected to couple the Mode 4 three-pulse interrogation to the delay means if it is received at the same time the I/P activate switch is in its operating position. The delayed three-pulse interrogation signal is coupled to the encoder and activates a Mode 2 reply. The ground equipment is also modified to enable it to faithfully reproduce the entire video output of its interrogator section.

Abstract: A method for eliminating signals from false targets in a secondary surveillance radar system includes the steps of obtaining plots of radar data for the same target. The range from the radar system to the targets is determined, and the target plot having smallest range of all target plots that indicate reflection of radar signals from the same target is accepted as being a real target. Other target data is rejected as being from a radar reflector. The coordinates of radar reflectors may be stored in a database to form a map of reflectors in the vicinity of the radar.

Abstract: A system for correlating secondary surveillance radar (SSR) data and ACARS data which results in a real time correlation of data which are unique to the separate existing systems. More specifically, a method is provided to attach flight identification data from ACARS signals to real time SSR data from Mode S transponders. Aircraft Mode S addresses are decoded and then converted to aircraft registration numbers using an algorithm or lookup table. Registration numbers are then correlated with registration numbers from decoded ACARS signals. The result is a real-time system which may provide an aircraft's registration information, including registration number, owner, make, and model, as well as its current flight identification number, and ACARS messages. As part of an aircraft multilateration system, the system provides an independent air traffic control picture complete with aircraft position and identification by flight number without the use of active radar equipment.

Abstract: A circuit and method for displaying a vertical profile view of situational awareness information.

Abstract: An apparatus and techniques for predicting conflicts between maneuvering aircraft which does not provide an excessive number of false alarms. The techniques utilize information to limit the time interval during which conflict predictions are made such that the predictions are made when they are most likely to be true.

Abstract: A surveillance transceiver system is provided for receiving extended squitters from Mode S transponders, translating the squitters into ADS-B state vectors in UAT format, and transmitting the ADS-B state vectors using a Universal Access Transceiver (UAT) datalink. The surveillance transceiver system bridges the gap created by differently-equipped aircraft by using multiple datalinks to provide seamless ADS-B surveillance. The module for processing the extender squitters includes a 1090 MHz receiver and a computer processor in communication with the UAT processor for parsing the squitter and composing the ADS-B state vector in UAT format for broadcast.

Abstract: The present invention provides a method for efficient use of the transmit power of a Traffic Alert Collision Avoidance System (TCAS) that allows enhanced surveillance range and limits radio frequency (RF) interference in crowded airspace. The method reduces power density in crowded airspace by modifying Mode S, Mode A and Mode C interrogations. During Mode S broadcasts, tracking interrogation power is reduced as a function of range. Further transmit power reduction is achieved by broadcasting a variable power density whisper-shout interrogation technique for Mode A/C aircraft when garbling is detected. If garbling is observed during a medium whisper-shout interrogation sequence, the method of the present invention attempts to clear the garbling by using focused high-density whisper-shout steps but only in the ranges where garbling was detected. Formation members can account for other formation members that are TCAS equipped using a special E-TCAS Broadcast Interrogation.

Abstract: An air traffic control support system comprises:

Abstract: System and methods for a ground based millimeter wave imaging system that provides real-time millimeter wave images of an airport to one or more aircraft from one or more ground stations (18). The system includes at least one millimeter wave transceiver (19) that is located in each one or more ground stations. Each at least one millimeter wave transceiver collects real-time millimeter wave images of the airport. At least one image processor (21) is operatively connected to the at least one millimeter wave transceiver, and processes the real-time millimeter wave images of the airport. At least one data link (22) allows communication of information between the one or more aircraft and the one or more ground station. The one or more ground stations transmit the processed realtime millimeter wave images to the one or more aircraft using the at least one link.

Abstract: There is provided an automatic airport information transmitting apparatus comprising: airport-inside-target detecting means for detecting a target inside an airport; target judging means for judging a target moved in a place within the airport, which is required to surveille an aircraft based upon target position information derived from the airport-inside-target detecting means; and transmitting means for transmitting information of the target inside the airport judged by the target judging means to an aircraft which is flying around the airport in a wireless manner. In a relatively small-scaled airport where no controller is present, the automatic airport information transmitting apparatus improves a flight security of aircraft which are flying around the airport and are landing at this airport.

Abstract: A reply is received from aircrafts for calibration in response to an interrogation of SSR stations to detect transmission timing of the interrogation of the SSR stations and directly-facing timing of antennas of the SSR stations and thus detect a position of an arbitrary aircraft based on the transmission timing and directly-facing timing and the reply from the aircraft.

Abstract: An SSR reply, which is sent out from an aircraft, is received and separated into one SSR reply to one SSR station and the other SSR reply to the other SSR station, thereby generating aircraft information of the aircraft based on one of the one SSR reply and the other SSR reply.

Abstract: A method, an apparatus and a computer program product are provided for accurately determining the vertical speed of an aircraft in a manner independent of signals provided by an air data computer, an inertial reference system and an inertial navigation system. Initially, a first vertical velocity of the aircraft is determined based upon a pressure altitude value associated with the aircraft. A second vertical velocity of the aircraft is also obtained from a GPS receiver carried by the aircraft. The first and second vertical velocities are then combined to determine the vertical speed of the aircraft. In this regard, the first and second vertical velocities are combined by complimentarily filtering the first and second vertical velocities. More particularly, the first vertical velocity is typically low pass filtered to remove high frequency noise that is attributable to the relatively low resolution of the first vertical velocity value.