Instrument landing system
AssigneeSundstrand Data Control, Inc.
InventorJohn P. Chisholm
Life of this patent
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Abstract
In a single-frequency precision guidance landing system, the use of a DME interrogator in the aircraft and a DME receiver at the ground installation, each tuned to the same DME channel frequency, to uniquely interrogate a selected ground station and hence identify it by virtue of its replies being synchronous in the aircraft with the interrogations, the interrogations and the replies also being used to obtain range to the ground installation. This technique uses airborne already-installed DME interrogators for selective interrogation of a desired landing installation, thereby to eliminate any need to add additional special purpose equipment to the aircraft to accomplish the desired uniqueness of interrogation and ground installation identification achieved by this invention.
Claims9
An improved landing system for landing an aircraft along a preferred landing guidance path including a predetermined glideslope and a centerline, the landing system being of the type having ground installations each including a trigger input operative in response to reception of an interrogating signal from a landing aircraft to actuate a transmitter to radiate a sequence of responses to the aircraft which responses include precision guidance signals radiated through directional guidance antennas directed along the guidance path, and the landing system having airborne installations each including means for receiving said responses and means for processing them to provide indications for guiding the landing of the aircraft, the improvements comprising:
- (a) at each participating ground installation, a TACAN/DME receiver tuned to a DME frequency assigned to that particular ground installation, the TACAN/DME receiver having a trigger output occurring in response to reception of an interrogating signal, which output is connected to the trigger input of the ground installation;
- and
- (b) in each participating aircraft an airborne installation including a TACAN/DME interrogator and antenna means for radiating interrogating signals to a ground installation, the interrogator being tunable to assigned DME frequencies whereby to select and uniquely interrogate a particular one of the ground installations, and the interrogator having a timing signal output connected to the airborne processing means for indicating the instant of transmission of each interrogating signal, whereby received responses to interrogating signals will be synchronous with the interrogating signals generated in a particular airborne installation.
In a system for guiding an aircraft along a path defined by a predetermined glideslope and a centerline, the system having:
- (a) a reference installation which includes a transmitter which radiates a sequence of responses to the aircraft in response to a trigger signal, the responses including precision guidance signals radiated through directional guidance antennas directed along the guidance path, the reference installation having a TACAN/DME receiver tuned to a DME frequency assigned to that reference installation, the TACAN/DME receiver having triggering means for providing a trigger signal to the trigger input of the transmitter, the trigger signal occurring in response to reception of an interrogating signal;
- and
- (b) an airborne installation which includes means for receiving and processing said responses to provide indications for guiding the aircraft to the reference installation, and having a TACAN/DME interrogator and antenna means for radiating interrogating signals to the reference installation, the interrogator being tunable to assigned DME frequencies to select and uniquely interrogate a particular reference installation, the improvement comprising:
- means, carried by the airborne installation, for receiving a timing signal form said interrogator which is representative of the instant of transmission of each interrogating signal and for synchronizing the received responses with the interrogating signals radiated by that airborne installation.
Dependencies are inferred from the claim text.