Thales

Thomson-csf

Philippe Billaud

Claude De Volder

Claude Rene De Volder

Michel Wybierala

Sylvain Colin

Philippe Joly

Daniel Barbier

Jean-Paul Parissenti

Didier Creveau

Lionel Largilliere

Jean-Marie Pannier

Philippe Hitz

The secondary radar includes an antenna having a radiation pattern forming a sum channel, designated SUM, a radiation pattern forming a difference channel, designated DIFF, and a pattern forming a control channel, designated CONT, the targets are located by implementing the following steps: detecting ADS-B squitters received via the CONT channel, via the SUM channel and via the DIFF channel; measuring at least the power of the squitters and their azimuth with respect to the radar; the location of a target transmitting ADS-B squitters being computed by exploiting at least the detection of one ADS-B squitter, in light of the latitudinal and longitudinal position of the radar and of the azimuthal measurement with respect to the radar, the position cell, designated the CPR cell, coded in the squitter being selected via the azimuthal measurement.

Secondary radar improving aerial safety via very-long-range ADS-B detection

The radar includes an antenna having a radiation pattern forming a sum channel, SUM, a radiation pattern forming a difference channel, DIFF, and a pattern forming a control channel, CONT, a first transmission and reception chain being associated with the SUM channel and a second transmission and reception chain being associated with the CONT channel, a reception channel being associated with the DIFF channel. Each of the transmission and reception chains is able to transmit and to receive simultaneously, the transmission chain comprising a filtering operation that filters signals transmitted at 1090 MHz and the reception chain comprising a filtering operation that filter signals transmitted at 1030 MHz, in such a way that the chains operate independently of one another.

Meta secondary radar

A density of Mode S interrogations and responses in the environment covered by a secondary radar is characterized according to the following steps: a first step wherein the radar: detects and locates Mode S targets by way of their synchronous responses to the interrogations emitted by the radar; detects asynchronous responses emitted by the Mode S targets, and not elicited by the radar; for each target, associates its asynchronous responses with its synchronous response to the radar; a second step wherein the radar: based on the association, determines the response rate of each target by counting the number of synchronous and asynchronous responses received from the target per given time period; with the environment being divided into elementary space cells, determines the response rate per cell by counting the number of synchronous and asynchronous responses received by each target in each cell, the rate characterizing the density of Mode S interrogations per cell.

Method for characterizing the density of mode S interrogations and responses and secondary radar implementing such a method

A method for detecting conflicts in the II/SI identification code of radars nearby a secondary mode-S radar, includes at least: a first step wherein the radar detects unsolicited unsynchronized replies, i.e. fruits, in a region of extended radar coverage; a second step wherein the radar detects a conflict in II/SI code by analyzing geographic regions of radar coverage common to the radar and to at least one nearby radar, a conflict being detected if the radar: detects, in the region of extended coverage, the presence of fruits that have as source the nearby radar; observes the absence of fruits caused by the nearby radar in that region of radar coverage of the radar which does not overlap with the region of radar coverage of the nearby radar; the region of overlap between the radar coverage of the radar and the radar coverage of the nearby radar forming a region of conflict in II/SI code.

Method for detecting conflicts in the II/SI identification code of a mode S radar with nearby radars, and secondary radar implementing such a method

A radar includes an antenna having a radiating pattern forming a sum channel, a radiating pattern forming a difference channel and a pattern forming a control channel, and generates at least interrogation messages on the sum channel and interrogation messages on the control channel; transmits messages via the sum channel and via the control channel respectively, and receives and processes signals received via the sum, difference, and control channels, configured for detecting replies of targets on the signals received via the sum and difference channels and carrying out monopulse processing and RSLS processing on the replies. The transmission is configured such that, for each target, the width of the beam for transmitting interrogations and receiving mode S selective replies is controlled based on the movement window of the target and position of the axis of the antenna in the window, to provide detection of the target by reducing the number of selective interrogations by a selective sub-interrogation of the target while ensuring precise positioning in azimuth: by pre-locating the target at the edge of the main reception lobe of the antenna by deviation measurement between the signals received on the difference and sum channels; and by selectively re-interrogating the pre-located target in mode S by calculation of the roll-call signal nearest to the centre of the main lobe to ensure precision in azimuth, without any other unnecessary supplementary interrogation.

Secondary radar with mode s adaptive beam control for each aircraft

Each pattern being associated with a reception channel, over a given time period, the unsolicited asynchronous replies, of long ADS-B squitters type, transmitted by targets present in the airborne environment of the radar, are detected, each of the squitters containing position information on the target which transmits it; for each detection, the long ADS-B squitter is decoded to check that the detected target is located in accordance with the position information contained in the squitter, the non-conforming detections being rejected; for each detection retained, the time of the detection, the value of the azimuth of the main beam of the antenna and the received power value on each of the reception channels is associated with the detection, the position information contained in the squitters giving the elevation segment wherein the detection is situated; the values obtained over the period being stored, the measured patterns being sampled, by elevation segment, from the stored values.

Method for measuring azimuth accuracy and patterns of the main antenna lobe of a secondary radar, and radar implementing such a method

An ADS-B spoofer being an false ADS-B squitter, an ADS-B squitter being an aircraft position information signal transmitted to secondary radars, the ADS-B squitters being detected over time at different bearings of the antenna in rotation of the radar, the method comprises, for each secondary radar, at least the following steps: a first step of detection of an ADS-B spoofer; a second step of location of the position in azimuth of the ADS-B spoofer generator, the second step comprising the following operations: measurement of the azimuth of the antenna of the secondary radar and of the received powers on the sum, difference and control patterns of the antenna upon the detection of an ADS-B squitter; generation and storage of at least one assumption of azimuth of the spoofer for each ADS-B squitter detected, the assumption being equal to the sum of the azimuth of the antenna and of the estimated bearing of the spoofer, the estimated bearing being characterized by the ratio of the received power on the sum pattern to the received power on the control pattern on the one hand and by the ratio of the received power on the difference pattern to the received power on the control pattern on the other hand.

Method for detecting and locating false ADS-B targets and secondary radar system implementing such a method

An each pattern is provided a reception pathway, the method uses the synchronous replies and the asynchronous replies, unsolicited of Fruit type, transmitted by targets present in the aerial environment of the radar and detected over a given number of antenna revolutions. At each detection of a reply the value of its off-aim in bearing and the value of relative power received on each of the pathways are calculated as is its elevation by extrapolation with the synchronous detections close to the same target and associated with the detection. The values obtained over the given number of revolutions are stored, the measured patterns being sampled on the basis of the stored values.

Method for measuring antenna patterns of a secondary radar and secondary radar implementing such a method

A test method in operational phase includes three distinct steps, a first step using the replies of the transponder to the interrogations in the Mode S transmitted in operational mode by the secondary radar to perform the measurement of the power of the transponder, and the measurement of the average rate of reply to the interrogations in Mode S transmitted by the radar intended for it; a second step which performs the measurement of the sensitivity of the transponder and a third step which carries out the test of its maximum rate of reply. The second step and the third step are carried out by modifying the operating parameters of the radar so that the additional interrogations required for the measurement can be performed, during the time interval following the last operational interrogation during which the aircraft remains located within the main Sum channel lobe of the antenna of the radar.

Method for measuring, in line operation, certain characteristics of the onboard transponder by using the secondary radar

A radar is provided which is mechanically and functionally independent of the primary radar; applies the principles of separation of emission pattern for each interrogation of any mode; of reception pattern for each reply of any mode; of assignment of the tasks which are specific thereto to distinct units. The radar includes one or more SSR/IFF interrogators dedicated at one and the same time to SSR surveillance and to gathering new mode S targets; and includes one or more other SSR/IFF interrogators for selective surveillance dedicated to mode S surveillance and to directed interrogations of IFF identification. The radar ensures simultaneous emission of the interrogations of the SSR/IFF interrogators in different azimuths, this simultaneous emission being enabled when the azimuthal spacing of the beams formed in emission ensures a decoupled level of jamming at the level of the transponders of the aircraft between the interrogations emitted by the respective sidelobes of the beams formed in emission.

Secondary radar with optimized spatio-temporal management

A radar is equipped with a main antenna having three radiation patterns, sum, difference and control, corresponding to the antenna, the radar comprises an auxiliary antennal device, composed of an antenna and of a rear radiating element which is situated at the rear of the antenna, fixed above the antenna and coupling means, the auxiliary antennal device: having three radiation patterns, sum, difference and control, the control pattern ensured for the direction opposite to the antenna by the rear radiating element; the antenna inclined to guarantee a maximum gain of its sum pattern in the elevational domain (60&#xb0;-90&#xb0;).

Secondary radar able to detect targets at high elevation

A method for the real-time management and sequencing of the information interchanges between a secondary radar and a plurality of aircraft includes the interchanges between the radar and a given aircraft being performed, depending on the aircraft concerned, either in a non-selective, SSR, IFF or 'All Call' interrogation mode or in a selective 'Roll Call' interrogation mode. According to this method, the information interchanges according to the non-selective interrogation modes are performed during successive periods specifically allocated to these modes, whereas each transaction forming an information interchange in selective mode between the radar and a given aircraft is temporally inserted into the time slots not used in periods by the interrogation-response tasks in non-selective mode. The method applies equally to the secondary radars exclusively dedicated to civilian air traffic control and to the secondary radars dedicated to combined civilian and military aircraft control tasks.

Method for optimizing the management of radar time for secondary radars operating in modes

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 &#x3a3;, &#x394; and monopulse of all the failed replies from the same target are exploited to construct the synthetic message. This processing operation is useful in highly polluted electromagnetic environments where the existing methods are inadequate: the same target may be asked the question again for reasons other than a reply failure.

Method for reducing multipath propagation effects during the processing of replies in mode 'S'

The invention relates to a method for pre-detecting responses in a secondary radar. It applies in particular to the detection of mode S responses. An aim of the invention is to process the signals received before decoding the responses so as to allow the detection of mixed responses, and avoid the detection of ghost responses. For this purpose, the invention has in particular as subject a method for pre-detecting responses in a secondary radar, the responses to be pre-detected comprising a message coded by a modulated signal, characterized in that the presence of a signal exhibiting modulation characteristics in accordance with those of a message of a response to be pre-detected is identified; the duration of the signal identified is measured; this duration is compared with a minimum duration, this minimum duration being determined on the basis of the duration of the messages of the responses to be pre-detected.

Method for pre-detecting responses in a secondary radar or application to the detection of mode S responses

The invention applies to secondary radars. It makes it possible to carry out filtering when seeking to detect SSR responses, these SSR responses being overlapped by a mode S response. According to the invention, the pulses of the mode S response are filtered without filtering the pulses of the SSR responses which are of a higher level than the mode S response. For this purpose, the subject of the invention is in particular a method for filtering a video signal, the video signal being received by a secondary radar, the filtering being designed to precede the detection of SSR responses, the received signal comprising samples intended to be analyzed according to the method, in which method for a sample under analysis:

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Limours, France

Philippe Billaud