Transponder transmissions may be monitored through a direct, shielded connection of an RF coupler to a transponder antenna cable. The RF coupler may be added on an antenna cable of an older-style transponder to pick up altitude and reply codes, decode the information and transmit it digitally for use by a separate external monitor. As such, the pilot may be afforded the ability to monitor the older-style transponder's altitude and reply code transmissions to air traffic control so as to determine if a failure of the transponder has occurred. By having the direct connection between RF coupler and the transponder antenna cable, no transmissions of other transponders would be received.

In some examples, a system that mounts on a vehicle includes a transceiver configured to transmit a first surveillance message including a first value for a quality parameter, wherein the first value indicates a first level of integrity or accuracy for the first surveillance message. The transceiver is also configured to receive a reply message to the first surveillance message. The system also includes processing circuitry configured to determine a second value for the quality parameter in response to the transceiver receiving the reply message, wherein the second quality parameter indicates a second level of integrity or accuracy for surveillance messages transmitted by the transceiver, and wherein the second level of integrity or accuracy is higher than the first level. The transceiver is configured to transmit a second surveillance message including the second value for the quality parameter in response to the processing circuitry determining the second quality parameter.

An electronic device includes memory circuitry, interface circuitry, and processor circuitry. The processor circuitry is configured to transmit, to a plurality of electronic reference devices, a first signal, the first signal having a pulse width below a threshold. The processor circuitry is configured to determine, based on the received second signals and at least one predetermined time period, a time of flight of each of the second signals. The processor circuitry is configured to obtain, from the memory circuitry, reference positions of the plurality of electronic reference devices. The processor circuitry is configured to determine, based on the associations, one or more candidate positions of the electronic device. The processor circuitry is configured to determine, based on the distances, the one or more candidate positions, and the obtained reference positions, a position of the electronic device.

Various communication systems may benefit from suitable architectures. For example, L-band radio frequency (RF) architectures may be beneficial to systems including avionics systems. A system can include a mode-s function as well as a traffic alert and collision avoidance system function separate from the mode-s function. The system can further include a directional antenna in reception and transmission connection with the traffic alert and collision avoidance system function. The system can additionally include an omni-directional antenna in reception and transmission connection with the mode-s function.

A method and system for determining a position of a non-cooperative object using a reflected signal from Secondary Surveillance Radar (SSR) system is disclosed. The method enables the ownship to detect a non-cooperative intruder, an aircraft which does not have a functioning transponder. The position and altitude of the non-cooperative intruder are determined from reflected signals by a phased array antenna or mechanically scanned directional antenna (MSDA) to perform tracking and avoidance of the non-cooperative object. In the case that a phased array antenna or MSDA is not available, a co-altitude assumption is applied to conservatively determine an avoidance area around the non-cooperative object, which defines coordinates to be tracked and avoided by the ownship.

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.

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.

A radar device includes a transmitter, a receiver and processing circuitry. The transmitter transmits a first pulse signal and a second pulse signal, a pulse width of the second pulse signal being wider than a pulse width of the first pulse signal. The receiver may receive a first reception signal including a reflection signal of the first pulse signal and a second reception signal including a reflection signal of the second pulse signal. The processing circuitry may be configured to compare, in a first section that is at least partly in a distance direction, a signal intensity of the first reception signal with a signal intensity of the second reception signal, and generate a display signal based on a result of the comparison.

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.