An antenna system for providing identification functionality comprising a main antenna and an auxiliary antenna, wherein the antennas are configured to at least transmit electromagnetic waves. The antenna system comprises a first channel interface and a second channel interface, a first switch and a transmission input means. The first switch is configured to switch between a first operation mode and a second operation mode. When set in the first operation mode the second channel interface is set to be in connection with the auxiliary antenna and when set in the second operation mode the second channel interface is set to be in connection with the main antenna. If transmission via the first transmission channel is expected the transmission input means is configured to set the first switch in the first operation mode. Thereby the main antenna can be used for transmission of signals both provided via the first and second channel interfaces and when transmission via the first and second channel interfaces simultaneously is required the signal provided via the first channel interface will be transmitted by the main antenna and the signal provided via the second channel interface will be transmitted by the auxiliary antenna.

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.

A method is provided for controlling transmission of an electronically steerable antenna system, wherein the electronically steerable antenna system comprises a signal generator configured to generate electromagnetic waveforms, and an antenna. The electronically steerable antenna system is configured for transmitting at least interrogation signals and ISLS control signals, and the method comprises the steps of, when transmitting the ISLS control signals: generating an electromagnetic waveform; applying a first transmission phase offset to the electromagnetic waveform, wherein the first transmission phase offset determines the phase offset between each antenna column pair; applying a second transmission phase offset to each antenna column of the second antenna half, wherein the second transmission phase offset of the second antenna half offset is 180 degrees in relation to the first antenna half; and transmitting the generated electromagnetic waveform whereto the first and the second phase offsets have been applied.

In one implementation, a method includes receiving a number of instances of a message that includes a self-reported position of a transmitter of the message from a corresponding number of satellite-based receivers that each received an RF transmission of an instance of the message. The method also includes determining the number of satellite-based receivers that received an instance of the message and selecting a validation technique based on the number of satellite-based receivers that received an instance of the message. If the number of satellite-based receivers that received an instance of the message is one, a propagation-based validation technique is selected. The method further includes determining a measure of the likelihood that the self-reported position of the transmitter is valid using the selected validation technique, and transmitting an indication of the measure of the likelihood that the self-reported position is valid.

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.

An antenna system for providing identification functionality comprising a main antenna and an auxiliary antenna, wherein the antennas are configured to at least transmit electromagnetic waves. The antenna system comprises a first channel interface and a second channel interface, a first switch and a transmission input means. The first switch is configured to switch between a first operation mode and a second operation mode. When set in the first operation mode the second channel interface is set to be in connection with the auxiliary antenna and when set in the second operation mode the second channel interface is set to be in connection with the main antenna. If transmission via the first transmission channel is expected the transmission input means is configured to set the first switch in the first operation mode. Thereby the main antenna can be used for transmission of signals both provided via the first and second channel interfaces and when transmission via the first and second channel interfaces simultaneously is required the signal provided via the first channel interface will be transmitted by the main antenna and the signal provided via the second channel interface will be transmitted by the auxiliary antenna.

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.

The present invention relates generally to a method and system (10) for classifying vehicle behaviour, particularly abnormal behaviour of civil aircraft (12). The method may comprise receiving aircraft data from an aircraft (12) which is to be classified; and determining whether the received aircraft data comprises identification information for the aircraft (12). In response to a determination that the received aircraft data comprises identification information, the method may comprise using said identification information to classify the behaviour of the aircraft (12). In response to a determination that the received aircraft data does not comprises identification information, the method may comprise obtaining the position of the aircraft and comparing the obtained position to an expected route for the aircraft to classify the behaviour of the aircraft (12).

The present invention refers to a method for controlling transmission of an electronically steerable antenna system, wherein the electronically steerable antenna system comprises a signal generator configured to generate electromagnetic waveforms, and an antenna. The antenna comprises an even number of antenna columns symmetrically arranged about a centerline of the antenna and thereby forming two symmetrical antenna halves. Respective antenna column comprises at least one antenna element configured at least for transmitting electromagnetic waves. The electronically steerable antenna system is configured for transmitting at least interrogation signals and ISLS control signals, and the method comprises the method steps of, when transmitting the ISLS control signals: generating an electromagnetic waveform; applying a first transmission phase offset to the electromagnetic waveform, wherein the first transmission phase offset determines the phase offset between each antenna column pair; applying a second transmission phase offset to each antenna column of the second antenna half, wherein the second transmission phase offset of the second antenna half offset is 180 degrees in relation to the first antenna half; and transmitting the generated electromagnetic waveform whereto the first and the second phase offsets have been applied. The present invention also relates to an electronically steerable antenna system configured to execute the method.

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.