NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Adaptive variable-length coding for efficient compression of spacecraft television data.An adaptive variable length coding system is presented. Although developed primarily for the proposed Grand Tour missions, many features of this system clearly indicate a much wider applicability. Using sample to sample prediction, the coding system produces output rates within 0.25 bit/picture element (pixel) of the one-dimensional difference entropy for entropy values ranging from 0 to 8 bit/pixel. This is accomplished without the necessity of storing any code words. Performance improvements of 0.5 bit/pixel can be simply achieved by utilizing previous line correlation. A Basic Compressor, using concatenated codes, adapts to rapid changes in source statistics by automatically selecting one of three codes to use for each block of 21 pixels. The system adapts to less frequent, but more dramatic, changes in source statistics by adjusting the mode in which the Basic Compressor operates on a line-to-line basis. Furthermore, the compression system is independent of the quantization requirements of the pulse-code modulation system.
Document ID
19720033735
Document Type
Reprint (Version printed in journal)
Authors
Rice, R. F.
Plaunt, J. R. (California Institute of Technology, Jet Propulsion Laboratory, Pasadena Calif., United States)
Date Acquired
August 6, 2013
Publication Date
December 1, 1971
Publication Information
Publication: IEEE Transactions on Communication Technology
Volume: COM-19
Subject Category
COMMUNICATIONS
Distribution Limits
Public
Copyright
Other