Abstract: A method and apparatus for predistorting digital signals so as to minimize radiation of harmonic signal energy during data transmission. The programmable waveshaping apparatus of the present invention is operative to predistort a binary encoded waveform to be transmitted over a transmission line. A pulse discriminator circuit is disposed to indicate the receipt of each pulse within an input sequence of short and long pulses included within the encoded waveform. Upon receipt of each short and long pulse an input logic network generates first and second sets of control signals, respectively. The logic network synthesizes the control signals based on information relating to sampled approximations of filtered versions of the short and long pulses. The inventive waveshaping apparatus further includes a programmable electrical source array for generating a sequence of line driving signals in accordance with each set of control signals.

Abstract: A frequency multiplexed system for coupling a plurality of individual telephone sets to at least one subscriber telephone line. The system includes a line adapter unit for controlling use of subscriber lines and for assigning the use of frequency bands to the individual telephone sets. The system includes a two-conductor interconnection cable for coupling to each of the telephone sets and to the line adapter unit. The system has a power-down mode in which the loss of external power allows each of the individual telephone sets to use the subscriber line. The line adapter unit and each of the individual telephone sets employ transconductance amplifiers so that modulated current signals are produced on the interconnection cable, thus allowing a plurality of voice signals to be summed together by voltage addition for conferencing between the telephone sets and the subscriber lines.