Integrated terminal area surveillance system
First Claim
1. An airport terminal area surveillance system comprised of a plurality of spaced apart interrogating and receiving stations having steerable antennas for directing an interrogation message along a relatively narrow beam radiated from said stations and for receiving replies from unsuppressed transponders illuminated by said beam, said replies being coded with information related to the identity or altitude of said transponders and including means responsive to said interrogations and resulting replies for determining the location of the replying transponder, said system including means for determining which of said stations is to direct an interrogation message to a particular transponder and which of said stations is to receive the resulting reply in accordance with the transponder location.
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Abstract
An integrated airport terminal area surveillance system, including a plurality of spaced apart interrogating and receiving stations and central equipment for controlling the stations operates in search and track modes by transmitting interrogation messages and receiving resulting replies. In the search mode the stations interrogate by directional beams all aircraft operating within the entire terminal area and enrolling the position and identification of replying aircraft into a system memory. In the track mode those aircraft enrolled in the system memory are individually interrogated. A system map is divided into memory cells corresponding to predetermined geographical cells. The means by which an aircraft is interrogated is determined by the geographical cell in which the aircraft is located.
21 Citations
7 Claims
- 1. An airport terminal area surveillance system comprised of a plurality of spaced apart interrogating and receiving stations having steerable antennas for directing an interrogation message along a relatively narrow beam radiated from said stations and for receiving replies from unsuppressed transponders illuminated by said beam, said replies being coded with information related to the identity or altitude of said transponders and including means responsive to said interrogations and resulting replies for determining the location of the replying transponder, said system including means for determining which of said stations is to direct an interrogation message to a particular transponder and which of said stations is to receive the resulting reply in accordance with the transponder location.
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4. A surveillance system for an airport terminal control area including a plurality of spaced apart interrogating and receiving stations and wherein transponder equipped aircraft cooperate with said stations, said stations being able to direct an interrogation message into a selected portion of said terminal control area and determine the location of a transponder equipped aircraft which receives said interrogation message and replies thereto and additionally including memory means for recording information defining the location of each said transponder equipped aircraft operating within said terminal control area and replying to interrogations, and means responsive to information defining the location of a transponder equipped aircraft to be interrogated for selecting which of said stations is to direct an interrogation message to that portion of said terminal control area in which said transponder equipped aircraft is located.
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5. A surveillance system for an airport terminal control area including a plurality of spaced apart interrogating and receiving stations and wherein transponder equipped aircraft cooperate with said stations, said stations being able to direct an interrogation message into a selected portion of said terminal control area and determine, in response to a reply to said interrogation message, the location of a transponder equipped aircraft which replies to said interrogation message by any of a plurality of algorithms for determining location in response to a reply to an interrogation and additionally including means for recording the location of said transponder equipped aircraft which replies to said interrogation message;
- and, means responsive to the recorded location for selecting which of said plurality of algorithms is to be used for determining the location of said aircraft in response to a subsequent reply.
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6. The method of locating transponder equipped aircraft operating within an airport terminal control area wherein an aircraft receiving an interrogation message transmits a reply a predetermined time after receipt of said message comprising:
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transmitting an interrogation message from at least one of a plurality of fixed, spaced apart stations to the location of an aircraft in accordance with information as to said location as recorded in a memory means; selecting, in accordance with information as to said location as recorded in said memory means, an algorithm for determining the new location of said aircraft from among a plurality of algorithms for determining the location of aircraft; selecting the station to transmit said interrogation message in accordance with information as to said location as recorded in said memory means; and
,recording said new location in said memory means. - View Dependent Claims (7)
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Specification