EFFECTIVENESS OF DATA COMPRESSION IN SPACE COMMUNICATION SYSTEMS.
Abstract
Efforts concern an investigative study of the compressibility of data transmitted from space vehicles. Phase I of this effort was devoted to the determination, by digital-computer simulation, of the degree of compression obtainable from actual flight-telemetry data, by use of Mark I data-compressor logic. Using deviation limit for each of sixty vehicle telemetry-data points compression ratios ranging from 27 to 39 were obtained for the orbital data, and a compression ratio of 19 was obtained for the launch data. In contrast to this, vibration data used in the study exhibited an average compression ratio of only 2 at a deviation-limit level of plus or minus 0.0156 of full scale - the value set by the data analysts. The conclusion drawn from this work is that the Mark I data compressor would be very effective in reducing the power and bandwidth requirements for the transmission of telemetry data similar to that used in this study, with the exception of the vibration data. An investigation was conducted to determine the buffer length necessary to smooth the flow of aperiodic data samples from the compressor for periodic transmission over the data link. This problem was attacked by both theoretical analysis and computer simulation. Phase II of the project was directed toward the ultimate goal of establishing optimum compression techniques. The major portion of this activity was devoted to the theoretical analysis of data compression. This analysis led to an expression relating the theoretical maximum-average-compression ratio to the power-spectral density of a normally distributed data signal, and the accuracy tolerance limits.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1962
- Accession Number
- AD0487635
Entities
People
- J. E. Medlin
- O. S. Saffir
- R. A. Schomburg
Organizations
- Lockheed Martin Missiles and Space