Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method and apparatus for enhancing aviation safety, ensuring that unmanned aircraft remain well clear of other flying objects, are disclosed. A control station acquires a direction of a path of a flying object and periodically transmits requests to a transponder of the flying object to acquire specific data. Upon receiving a response to a request, a range of the flying object from the control station is determined. Using data acquired from each three consecutive responses, the displacement magnitude, the speed, and angular displacements of the flying object are determined. The method assesses potential crossing of a protection zone surrounding a protected aircraft based on most recent acquired data.