A detect-and-avoid system for an ownship aircraft is disclosed. The system has a control station in communication with an ownship aircraft, and a Passive Secondary Surveillance Radar (PSSR) system at the ownship aircraft. The PSSR is equipped to receive a reply from a target object, in response to an interrogation signal of staggered P1 and P3 pulses sent by a narrow-beam antenna of a Secondary Surveillance Radar (SSR) to the target object, and also to receive P2 pulses transmitted by a wide-beam antenna of the SSR. A pulse repetition frequency (PRF) pattern for the staggered interrogation signal is determined, followed by estimating a transmit time of the interrogation signal, and determining a position of the target object. A corresponding detect-and-avoid method is also disclosed.

Systems and methods relating to air traffic control and navigational aids for aircraft. An antenna system uses a multi-sector sensor that uses two vertical column antenna arrays per sector. Each pair of vertical column antenna arrays produces two beams that are off a boresight for each pair of antenna arrays. Wide angle monopulse processing is used to determine an azimuth or angle of arrival for an aircraft using at least one pair of the vertical column antenna arrays. Predetermined correction factors are applied to the azimuth for specific elevation values and, for elevation values without predetermined correction factors, interpolation between known predetermined correction values to arrive at the corrector factor to be applied.

Method for determining a staggered pattern and interrogation mode pattern of an Secondary Surveillance Radar (SSR) is disclosed. The method enables a Passive SSR (PSSR) to work not only inside but also outside the SSR beam. When PSSR is in the wider beam of the SSR, multiple P2-pulses are detected as time-ordered sequence of P2-pulse intervals, from which a repeating sequence and further a stagger pattern is determined. The interrogation mode pattern is determined by comparing the staggered pattern with the interrogation signals. A transmit time of the P3-pulse is predicted based on the staggered pattern and the interrogation mode pattern. Corresponding system is also provided.

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.

An electronic device (such as a transponder or an aircraft that includes the transponder) is described. This electronic device may include: one or more omnidirectional antennas; and one or more integrated circuits (such as one or more radios) that transmit and receive RF signals. During operation, the electronic device may receive, using the one or more omnidirectional antennas, broadcast information associated with a second electronic device (such as a second transponder or a second aircraft that includes the second transponder), where the broadcast information is compatible with a regulation from a government aviation or aviation safety administration (such as the Federal Aviation Administration or the European Union Aviation Safety Agency). Then, the electronic device may determine a track of the second electronic device based at least in part on the broadcast information.

The present invention provides a low-cost and low-volume mode A/C/S transponder positioning system to detect the position of a target aircraft, or intruder, outside the range of a secondary surveillance radar system. The system uses a signal of the intruder to pinpoint the location of the intruder. The system can be used on both the ground and on an aircraft in a full 360 degree range around the system.

The disclosure provides ranging methods and apparatuses. One example method includes that a first device sends a first signal on a first channel. The first device receives, on a second channel, a second signal from a second device, where the second signal is a signal obtained after frequency conversion is performed on the first signal. The first device calculates a distance between the first device and the second device based on a phase difference between carriers of the second signal.

Methods and systems are disclosed for determining a spatial position of an aircraft, without replying on measurements from the Global Positioning System. Various embodiments are described using a single Secondary Surveillance Radar (SSR), and multiple SSRs.

Embodiments described herein are concerned with system for identifying an aerial vehicle. The system comprises: a radar sub-system, the radar sub-system comprising at least one radar connectable to a static support member and a transceiver configured to transmit data indicative of one or more targets identified by the radar within an airspace; a receiver arranged to receive the data indicative of one or more targets identified by the radar; and a processing system configured to process said data, whereby to identify at least one aerial vehicle. In some embodiments the radar comprises a marine radar.

An enhanced L-band Digital Aeronautical Communications System (LDACS) includes a plurality of LDACS ground stations, each transmitting a respective carrier signal. An LDACS airborne station may be configured to communicate with the plurality of LDACS ground stations and determine position information based upon respective Doppler shifts in the plurality of carrier signals.