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.