An adaptive interrogation method is provided, the method including determining application of an adaptive whisper shout interrogation sequence. The determination may be predictive and based on an anticipation of garbled replies or may be reactive and based on a plurality of replies to an initial ATCRBS interrogation, there being interference between the replies such that the replies are unable to be properly decoded. The adaptive whisper shout interrogation sequence includes adapting a subsequent ATCRBS interrogation. The adaptation may be a change in an amplitude difference between an interrogation pulse and a suppression pulse of the subsequent ATCRBS interrogation (i.e. a bin width), as compared to the initial ATCRBS interrogation; or the adaptation may be a change in a power of the subsequent ATCRBS interrogation as compared to the initial ATCRBS interrogation. The subsequent ATCRBS interrogation is then transmitted, and one or more replies are received.

A traffic collision avoidance system (TCAS), configured to transmit a wide transmit beam of approximately 180 degrees. The wide transmit beam may be, for example at the interrogation frequency or a transponder response frequency. The TCAS of this disclosure includes a directional antenna system with two signal input ports and two or more antenna elements. In some examples, the direction of the 180 degree beam may be controlled by the phase relationship between the signals input to the two port antenna. In other examples, the direction of the transmit beam from the antenna system is predefined to be in two complementary directions (e.g., forward and aft).

A traffic collision avoidance system (TCAS), configured to transmit a wide transmit beam of approximately 180 degrees. The wide transmit beam may be, for example at the interrogation frequency or a transponder response frequency. The TCAS of this disclosure includes a directional antenna system with two signal input ports and two or more antenna elements. In some examples, the direction of the 180 degree beam may be controlled by the phase relationship between the signals input to the two port antenna. In other examples, the direction of the transmit beam from the antenna system is predefined to be in two complementary directions (e.g., forward and aft).

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.

An avian detection system for determining risks of collision between a collision object and bird objects includes avian radar system(s) providing a first type of information data relating to objects detected, and a transponder receiver receiving transponder data transmitted or broadcasted by transponders provided at the collision objects. Processors are configured to receive first type of information data corresponding to the detected objects and provide radar plots. The processors are further configured to receive the transponder data and provide transponder plots, to create and store a number of object tracks based on the provided radar plots and transponder plots, with each track holding object data corresponding to or determined from data of matching plots, and to determine one or more risks of collision or collision risk levels for the collision object based on object data of a plurality of the obtained object tracks.

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.

Disclosed herein are systems for routing wireless communications. Some systems may include an apparatus comprising an enclosure configured to attach to an external portion of an aircraft and which may contain: a wireless communications device, and an antenna in communication with the wireless communications device and configured to send or receive signals to and/or from aircraft.

A need exists for a method to do monopulse tracking with a single beam phased array antenna. With a monopulse tracker antenna, the satellite, or moving target, will have a beacon signal that the tracker can acquire. The beacon signal may be a preamble in the transmitted signal from the satellite. The monopulse tracker antennas are scanned over the volume, minimizing the error signal. When the error signal is minimal, the antenna is pointed in the direction of the satellite or moving target. Because the tracker needs to know direction offsets in both azimuth and elevation planes, error signals from both planes are needed. The monopulse tracker antenna maintains a radio frequency link to the beacon signal, causing the antenna to lock in the direction of the satellite when the error signal is minimized to zero.

A method according to the present invention includes calculating, based on a reported position of a vehicle, a probability that an actual position of the vehicle is within a region of interest. The method further includes determining whether a threat of a collision exists between the vehicle and an object based on the probability that the actual position of the vehicle is within the region of interest and a reported position of the object. The method further includes generating an alert if it is determined a threat of a collision exists between the vehicle and the object.

Various communication systems may benefit from suitable use of redundancy. For example, surveillance systems in avionics applications may benefit from having functional redundancy. A system can include a collision avoidance or alerting system function in wired connection to a directional antenna. The system can also include a first mode-S transponder function in wired connection to the directional antenna. The system can further include a second mode-S transponder function in wired connection to the directional antenna, wherein the first mode-S transponder function is independent from the second mode-S transponder function.