Abstract:
A satellite communications system employs separate subsystems for providing broadcast and point-to-point two-way communications using the same assigned frequency band. The broadcast and point-to-point subsystems employ an integrated satellite antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones in a manner which permits multiple reuse of the entire band of assigned frequencies. A single pool of solid state transmitters allows rain disadvantaged users to be assigned higher than normal power at minimum cost. The intermodulation products of the transmitters are geographically dispersed.
Abstract:
A satellite communications system employs separate subsystems for providing broadcast and point-to-point two-way communications using the same assigned frequency band. The broadcast and point-to-point subsystems employ an integrated satellite antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones in a manner which permits multiple reuse of the entire band of assigned frequencies. A single pool of solid state transmitters allows rain disadvantaged users to be assigned higher than normal power at minimum cost. The intermodulation products of the transmitters are geographically dispersed.
Abstract:
A satellite communications employs separate subsystems for providing broadcast and point-to-point two-way communications using the same assigned frequency band. The broadcast and point-to-point subsystems employ an integrated satellite antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones in a manner which permits multiple reuse of the entire band of assigned frequencies. A single pool of solid state transmitters allows rain disadvantaged users to be assigned higher than normal power at minimum cost. The intermodulation products of the transmitters are geographically dispersed.
Abstract:
An apparatus and method for launching a spacecraft (200) including a payload (202) and a delivery stage (204) having a rocket engine (37) powered by fluid bipropellant (114) from the earth into a high energy orbit and for recovering the delivery stage (204). By reducing the delivery stage mass, it becomes feasible and cost effective to recover the delivery stage (204) for reuse. Delivery stage mass is reduced by several techniques including transporting the spacecraft (200) and the fluid bipropellant (114) to a parking orbit with the fluid bipropellant in tanks (20-26) external to the spacecraft (200); transferring the fluid bipropellant (114) to light weight tanks (30-36) integral to the spacecraft (200); controlling the relative flow rates of the fluid bipropellant constituents to the rocket engine (31) during firing of the rocket engine (37) to ensure complete use of both bipropellant constituents; and controlling ascent and descent maneuvers from remote tracking stations. A space shuttle (42) can be used to transport the spacecraft (200) and fluid bipropellant (114) in its cargo bay (40) to the parking orbit and recover the delivery stage (204) at the end of a mission. The invention is particularly useful for delivery of payloads to geosynchronous orbits.
Abstract:
A method for controlling the utilization of a fluid bipropellant including two respective constituents separately in respective tanks aboard a spacecraft for consumption by a spacecraft rocket engine, comprising the steps of actuating the rocket engine; during the actuation of the rocket engine, providing a flow of bipropellant constituents to the rocket engine in a first proportion; after the actuation of the rocket engine, measuring the amount of at least one bipropellant constituent in a bipropellant tank containing the constituent; adjusting a pressure level within at least one bipropellant tank relative to a pressure level within another bipropellant tank based upon the amount of said at least one bipropellant constituent in a bipropellant tank containing said at least one constituent; after the measuring step, actuating the rocket engine; during the actuation of the rocket engine after the measuring step, providing a flow of bipropellant constituents to the rocket engine in a second proportion based upon said adjusted pressure level within said at least one bipropellant tank relative to a pressure level within said another bipropellant tank.
Abstract:
Un amplificateur d'enveloppe à rendement élevé (20) comporte une alimentation électrique (24), un comparateur (60), et plusieurs commutateurs (26-38). L'alimentation électrique (24) peut fournir de multiples sorties. Le comparateur (60) mesure l'amplitude d'un signal d'entrée par rapport à un parmi plusieurs niveaux de seuil. Lorsque le signal d'entrée se situe dans une plage prédéterminée, une sortie sélectionnée d'alimentation électrique est commutée sur le cheminement de sortie. La présente invention permettant la commutation incrémentielle de faibles quantités de puissance, les pertes de commutation sont sensiblement atténuées.
Abstract:
Système de communications par satellite permettant la communication entre des postes mobiles (11, 12, 14) et fixes (16). Le système de communications comprend une pluralité d'utilisateurs mobiles (11), un satellite (33) en orbite géo-synchrone envoyant des signaux de liaison montante et descendante adressables en fréquence aux postes mobiles (11, 12, 14), une station de base (10) recevant les signaux provenant du satellite et transmettant des signaux vers ce dernier et une pluralité d'utilisateurs fixes (16) couplés à la station de base (10). Ce système présente l'avantage de la réutilisation des fréquences et l'adressage en fréquence des émissions à liaison montante et descendante des utilisateurs mobiles (11, 12, 14).
Abstract:
A satellite communications system employs separate subsystems for providing broadcast and point-to-point two-way communications using the same assigned frequency band. The broadcast and point-to-point subsystems employ an integrated satellite antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones in a manner which permits multiple reuse of the entire band of assigned frequencies. A single pool of solid state transmitters allows rain disadvantaged users to be assigned higher than normal power at minimum cost. The intermodulation products of the transmitters are geographically dispersed.
Abstract:
A satellite communications system employs separate subsystems for providing broadcast and point-to-point two-way communications using the same assigned frequency band. The broadcast and point-to-point subsystems employ an integrated satellite antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones in a manner which permits multiple reuse of the entire band of assigned frequencies. A single pool of solid state transmitters allows rain disadvantaged users to be assigned higher than normal power at minimum cost. The intermodulation products of the transmitters are geographically dispersed.
Abstract:
A satellite communications system employs separate subsystems for providing broadcast and point-to-point two-way communications using the same assigned frequency band. The broadcast and point-to-point subsystems employ an integrated satellite antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones in a manner which permits multiple reuse of the entire band of assigned frequencies. A single pool of solid state transmitters allows rain disadvantaged users to be assigned higher than normal power at minimum cost. The intermodulation products of the transmitters are geographically dispersed.