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Direct Data Distribution From Low-Earth OrbitNASA Lewis Research Center (LeRC) is developing the space and ground segment technologies necessary to demonstrate a direct data distribution (1)3) system for use in space-to-ground communication links from spacecraft in low-Earth orbit (LEO) to strategically located tracking ground terminals. The key space segment technologies include a K-band (19 GHz) MMIC-based transmit phased array antenna, and a multichannel bandwidth- and power-efficient digital encoder/modulate with an aggregate data rate of 622 Mb/s. Along with small (1.8 meter), low-cost tracking terminals on the ground, the D3 system enables affordable distribution of data to the end user or archive facility through interoperability with commercial terrestrial telecommunications networks. The D3 system is applicable to both government and commercial science and communications spacecraft in LEO. The features and benefits of the D3 system concept are described. Starting with typical orbital characteristics, a set of baseline requirements for representative applications is developed, including requirements for onboard storage and tracking terminals, and sample link budgets are presented. Characteristics of the transmit array antenna and digital encoder/modulator are described. The architecture and components of the tracking terminal are described, including technologies for the next generation terminal. Candidate flights of opportunity for risk mitigation and space demonstration of the D3 features are identified.
Document ID
19970017397
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Budinger, James M. (NASA Lewis Research Center Cleveland, OH United States)
Fujikawa, Gene (NASA Lewis Research Center Cleveland, OH United States)
Kunath, Richard R. (NASA Lewis Research Center Cleveland, OH United States)
Nguyen, Nam T. (NASA Lewis Research Center Cleveland, OH United States)
Romanofsky, Robert R. (NASA Lewis Research Center Cleveland, OH United States)
Spence, Rodney L. (NASA Lewis Research Center Cleveland, OH United States)
Date Acquired
September 6, 2013
Publication Date
April 1, 1997
Subject Category
Space Communications, Spacecraft Communications, Command And Tracking
Report/Patent Number
NAS 1.15:107438
E-10703
NASA-TM-107438
Meeting Information
Meeting: International Conference on Communications
Location: Montreal
Country: Canada
Start Date: June 8, 1997
End Date: June 12, 1997
Sponsors: Institute of Electrical and Electronics Engineers
Accession Number
97N19676
Funding Number(s)
PROJECT: RTOP 315-90-2G
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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