NDLI: Applications technology satellites F and G communications subsystem

Content Provider	IEEE Xplore Digital Library
Author	Sabelhaus, A.B.
Copyright Year	1963
Abstract	The communications subsystem comprises the 30-ft parabolic reflector, the composite feed system, and the multiple frequency transponder. For high reliability, redundancy is used as required in these assemblies. The high effective radiated power (ERP) provided by this subsystem allows it to function as part of the experiments, in addition to performing as the interface between the spacecraft and the ground stations. Therefore, in addition to meeting the communications design requirements, the subsystem has been designed to meet the requirements for performance of several technical objectives, namely accurate pointing of a radiated beam to either an earth station or another satellite, and high ERP. Successful performance of these objectives is a requirement in the Position Location and Aircraft Communications Experiment, Tracking and Data Relay Experiment, and Instructional Television experiments. The composite feed subassembly, which provides radiating and receiving elements for the S, L, C, and UHF frequency bands, is used in conjunction with the high-gain RF reflector to provide optimum antenna performance. The transponder is the interface between the onboard experiments and ground stations and comprises the receiver, IF amplifier, and transmitter assemblies which perform frequency generation, translation, and power amplification functions. The receivers, operating at C, S, and L band, perform preamplification, and down-convert the RF signal to the 150-MHz IF. The IF amplifier assembly uses input switching to allow connection of a down-converter output to any of the three IF amplifiers; and output switching is used to connect an IF output to the desired up-converter. This achieves high reliability with maximum flexibility. The transmitters up-convert the IF signals which are then amplified by a traveling-wave tube amplifier (TWTA) or solid-state amplifier and fed to the appropriate composite feed elements. A synthesizer provides multiple mixing frequencies for up and down conversion in coherent and noncoherent modes of operation.
Sponsorship	IEEE Publication
Starting Page	206
Ending Page	212
Page Count	7
File Size	763720
File Format	PDF
ISSN	00189219
Volume Number	59
Issue Number	2
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	1971-02-01
Publisher Place	U.S.A.
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Artificial satellites Feeds Frequency Assembly Satellite ground stations Radiofrequency amplifiers Satellite broadcasting Transponders Enterprise resource planning Transmitters
Content Type	Text
Resource Type	Article
Subject	Computer Science Electrical and Electronic Engineering

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3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
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