Abstract: A monopulse secondary surveillance radar is configured to integrate replies to active interrogations and passive squitter reception into a single surveillance system, and includes: a three-channel antenna arrangement; a redundant ADS-B antenna arrangement including a first and second omnidirectional ADS-B antenna, each having a low noise amplifier, and each being integrated with a GPS antenna; and a pair of redundant four-channel interrogators. The three-channel antenna arrangement is configured to transmit interrogations, and to receive corresponding replies from an aircraft transponder. The first ADS-B antenna is coupled to a first of the pair of redundant four-channel interrogators, and the second ADS-B antenna is coupled to a second of said pair of redundant four-channel interrogators, for the monopulse secondary surveillance radar to provide real-time passive detection of ADS-B-equipped aircraft and active radar detection of aircraft to each of the pair of redundant four-channel interrogators.

Abstract: A secondary surveillance radar with rotating antenna, configured for transmitting interrogations in S or IFF mode and processing the responses to these interrogations. The radar includes an antenna having a lobe with three channels, a Sum channel, a Difference channel and a Control channel, whose transmission means are configured for transmitting interrogation messages over the Sum and Difference channels and whose reception and processing means are configured so as to carry out, aside from conventional detections by the Sum channel, detections by the Difference channel of the responses from the aircraft having been subjected to interrogation by this same channel. The radar also includes means for Space-Time Management configured for generating interrogation messages and determining whether a given message is to be transmitted by the Sum channel, by the Difference channel or by the two channels simultaneously and controlling its transmission by the corresponding transmission channel.

Abstract: The processing method according to the invention is a method of processing replies from targets interrogated by a surveillance radar according to a mode S interrogation of all the targets present in the receiving lobe of the radar, whereby the different targets present in the receiving lobe of the radar are interrogated at least once, the set of the mode S reply signals received for this lobe are collected after each interrogation, a reply detection processing operation is performed for each target and errors are detected and, if necessary, corrected then the corresponding blips are extracted, and this method is characterized in that said signal quality detection and determination processing operation consists in forming a synthetic message with the set of replies to each interrogation for each target, establishing, for each bit of the message, the value and the quality of this bit and performing the error detection and correction using this synthetic message, and the three variables ?, ? and monopulse of all

Abstract: Very efficient sidelobe suppression of Barker codes is achieved through the use of a mismatched filter, which is comprised of a conventional matched filter cascaded with a computationally efficient filter based on multiplicative expansion. Several constant parameters are introduced in the terms of the expansion and are optimized to improve the performance of the filter. Optimized mismatched filters for length 13, 11, 7 and 5 Barker codes are presented. For each of these codes, filters with one, two and three stages are studied. The technique is extended to compound Barker codes based on their representation in a factored form in the z-domain. Hardware requirements for the filters discussed in the disclosure are also presented.

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 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: The invention relates to a method of interference suppression in a radar system and also to a system operating according to the method. The system incorporates a first antenna and associated electronic circuits for emitting interrogating radar radiation towards a remote scene. Moreover, the system also incorporates a second antenna and associated electronic circuits for receiving interrogating radiation reflected from the scene and generating corresponding first and second processed signals. The first and second processed signals correspond to a broader main beam response of the antenna and to a narrower main beam response thereof respectively. By mutually comparing the first and second processed signals, the system is operable to identify those second processed signals affected by interference from the scene.

Abstract: Weather information is stored in a weather information storage unit. Information of aircraft flight situation, flight plan, air traffic flow management, and condition status is stored in an aircraft information storage unit. On the basis of information stored in the weather information storage unit and the aircraft information storage unit, arrival time of each arriving aircraft and departing aircraft is predicted by an arrival time prediction unit and a departure time prediction unit. The information of the estimated time thus predicted is stored in an estimated time of takeoff and landing storage unit. On the other hand, on the basis of information stored in information storage units, runway use time is assigned to each arriving aircraft and departing aircraft by a takeoff and landing assignment unit in accordance with Control System Standards. Runway reservation information thus obtained is stored in a reservation information storage unit.

Abstract: The accuracy of multilateration systems can be greatly improved by using a correction method based on the SLS (Sideband Lobe Suppression) signal produced by a Secondary Surveillance Radar (SSR). Multilateration is a cooperative surveillance technique for aircraft equipped with Air Traffic Control Radar Beacon System (ATCRBS), Mode S, or Automatic Dependent Surveillance Broadcast (ADS-B) transponders. When one of these transponders aboard a vehicle is interrogated, it responds by broadcasting a message based on what the interrogation requests. These reply messages may be multilaterated to determine the source position of the transmission. Multilateration is a Time Difference of Arrival (TDOA) technique similar to triangulation. Multilateration can be performed to locate the transmission source of any SSR signal.

Abstract: A radar apparatus that is provided with auxiliary antennas (5, 10) of an omnidirectional nature. In addition to customary ECCM applications, such as side-lobe suppression and side-lobe blanking, the auxiliary antennas (5, 10) are also used for the emission of frequency-shifted pulses which are emitted simultaneously with radar transmitter pulses. To this effect, the radar apparatus is provided with auxiliary transmitters (8, 13). Furthermore, auxiliary receivers (6, 11) have been provided for analyzing the responses of jammers to the frequency-shifted pulses.

Abstract: A communication system for receiving aircraft reply squits (transmissions) normally used in a radar beacon system for surveilling aircraft in a given geographic area. The communication system includes a plurality of omnidirectional receivers, each receiver having a function of omnidirectionally receiving the aircraft squits and developing therefrom two types of information strings, namely a data string, indicative of a message in the aircraft squit, and a corresponding confidence string indicative of the reliability of the developed data string. A data communication link transmits the data and confidence strings between the plurality of omnidirectional receivers and the master data processor.

Abstract: A sidelobe suppression system including an antenna with a variable phase ter, a transmitter for transmitting an expanded phase-coded pulse, a receiver for receiving target echos, a pulse expander/compressor for phase coding the expanded transmitted pulse with a phase code, P, and for compressing target echos with unscrambled phase code P and a control unit for shifting the phase center of the antenna to scramble the phase codes of the expanded pulses transmitted into the antenna sidelobes.

Abstract: An MLS system comprising ground based equipment which includes a microwave signal transmitter arranged to feed microwave signals to radiator elements of an array antenna via phase shifter modules one of which is provided for each of the said elements, whereby the production of a scanned microwave signal beam is facilitated, signal monitor/detector means effective to provide a detected sample signal derived from the scanned beam, filter means responsive to the detected sample signals for providing a filtered signal derived in dependence upon effective sidelobe signals in the said beam, and comparator means responsive to the filtered signal for providing a transmitter shutdown signal when the filtered signal exceeds a predetermined threshold level for more than a predetermined time during a predetermined number of successive scans.

Abstract: A method and apparatus for identifying a remote target includes a transmitter for transmitting pulses of energy toward the target for generating echo signals, and a receiver for receiving the echo signals, and for generating received signals representing the target, noise and clutter. The received signals are applied through a plurality of cascaded channels, each including a Doppler filter cascaded with a multiplier, each also including range sidelobe suppression, for, in each of the cascaded channels, narrowband filtering the signals passing therethrough about a controllable center frequency, and for, if necessary, converting the signals passing therethrough to baseband, for thereby applying one of a plurality of Doppler filtered baseband signals to the input of each of the range sidelobe suppressors of each of the cascaded channels. The power of the Doppler filtered baseband signals in each range bin is evaluated for determining the frequency at which the spectral density is greatest.

Abstract: Apparatus for rejecting multipath reply signals received from a target transponder within a selectable time period, comprising: a top antenna and a bottom antenna to detect reply signals; means for determining an altitude code associated with each reply signal detected by the antennas respectively; means for determining a differential time of arrival (DTA) value for each reply signal detected by the antennas respectively; and processing means for: 1) producing, for each top antenna reply signal, a top antenna target report that includes the altitude code and DTA values; 2) producing for each bottom antenna reply signal, a bottom antenna target report that includes the altitude code and DTA data; and 3) comparing each top antenna report data with corresponding data from each bottom antenna report, and marking out each bottom antenna report that is a multipath reply based on such comparison.

Abstract: An airport surface traffic surveillance and automation system addresses a wide variety of airport surface conflict scenarios using a combination of runway-status lights, controller alerts, and enhanced controller displays. Runway-status lights, composed of runway-entrance lights and takeoff-hold lights, provide alerts directly to pilots and vehicle operators, to prevent runway incursions before they happen. Controller alerts are used to direct a controller's attention to existing conflicts between aircraft on or near the runways. Enhanced displays present symbology to describe aircraft position, size, direction and speed of motion, altitude, aircraft flight number, and equipment type. Aircraft on approach to runways are also depicted on the displays.

Abstract: This invention concerns a secondary radar antenna operating in S mode.The antenna comprises a row of columns (1) of radiating elements powered by a hyperfrequency distribution circuit (2) containing a summing channel (.SIGMA.), a difference channel (.DELTA.) and a secondary lobe suppression channel (.OMEGA.), each producing a radiation diagram. The antenna end columns (L, R) each produce at least one auxiliary radiation diagram offset with respect to the diagram produced by the summing channel and contributing with the other antenna columns (1) to the creation of the other three diagrams.Application: secondary radars in S modes in communication with a large number of aircraft per antenna revolution.

Abstract: A method for inhibiting responses by transponders to interrogation signals originating in the side lobes of an interrogating radar of a secondary radar system. The interrogating radar first transmits a reference signal with the highest power level of the reference signal being directed into a zone of interest to the interrogating radar. The interrogating radar then transmits a control signal having a higher power level than the reference signal in all regions of space except within the zone of interest. The control signal is of substantially longer duration than the reference signal. A transponder receives, detects and measures the peak amplitude of the reference signal and establishes a minimum trigger level (MTL) at a predetermined level below the reference signal peak. The control signal is received, detected and integrated. The peak amplitude of the integrated control signal is compared with the MTL.

Abstract: A multipurpose system provides radar surveillance for air traffic control purposes. The system includes four separate active phased-array antennas, each with .+-.45.degree. coverage in azimuth, from 0.degree. to 60.degree. in elevation. Each antenna element of each phased-array antenna is coupled by a low-loss path to the solid-state amplifier associated with a transmit-receive (TR) module. Each antenna produces a sequenc of pencil beams, which requires less transmitted power from the TR modules than a fan beam, but requires more time beacuse the pencil beam must be sequenced to cover the same volume as the fan beam. In order to scan the volume in a short time, the PRF is responsive to the elevation angle of the beam, so higher elevation angles use a higher PRF. Low elevation angle beams receive long transmitter pulses for high power, and pulse compression is used to restore range resolution, but the long pulse results in a large minimum range within which targets cannot be detected.

Abstract: A system and method for detecting and removing specular multipath reports from terminal ATCRB systems for aircraft targets having Mode 3/A transponder reporting capabilities. Reports are delayed for a first time, or azimuth, interval to determine whether the report is multipath or to identify future occurrences of multipath reports. After the first azimuth interval, the report is released for display and a fragment of the report is retained for an additional azimuth interval. Of two reports with matching Mode 3/A code, the one with the greater range is considered to be a multipath reply. If the multipath report range falls within a multipath range interval and has not been released for display, it is discarded by the system as an erroneous report.

Abstract: A secondary surveillance radar system in which monopulse processing is used to obtain angle estimation of azimuth bearing, involving a monopulse processor, two independent phase detectors in respective A and B channels, the arrangement being such that a log amplifier is provided in each of the respective channels and the outputs of these log amplifiers are coupled to the independent phase detectors, whereby a resultant signal is obtained giving target deviation from boresight in either direction based on differences in phase between signals appearing in the respective channels.

Abstract: The invention regards a perfectioning in reply type radar systems, in particular SSR (Secondary Surveillance Radar) or IFF (Identification Friend or Foe). The invention has as its aim that of eliminating or reducing undesired replies due to reflections from fixed obstacles or from structural peculiarities in the main radar system (i.e. radome) and other similar effects. The suppression of undesired replies is attained by varying azimuthally the emission power of the radio-frequency impulses according to a memorized law.