Abstract: Magnification/reduction is achieved by a single FIR filter under the control of a Digital Differential Analyzer (DDA) as would be used to simulate a perfectly straight line on a two-dimensional raster. The single FIR filter combines the processes of interpolation, filter, and decimation. The DDA is programmed with the desired magnification/reduction ratio and provides signals that control shifting of input samples into the FIR filter and selection of FIR coefficients for the FIR filter.

Abstract: A subscriber terminal ms sends the demand including at least information for identifying the demand subscriber terminal, information for identifying the requested information, and information relating to the urgency of the requested information to the information distribution transmission center HE through the going-up line. The information distribution transmission center HE plans a transmits information requested according to the transmission schedule of the information based on this demand, and transmits the transmission schedule information included in the going-down control data to the subscriber terminal which sent the demand prior to the actual transmission, and transmits the requested information according to the above-mentioned transmission schedule.