BASE BAND TO DI PHASE CONVERTER AND DATA TRANSFER SYSTEM USING THIS BASE BELT TO DI PHASE CONVERTER.

摘要

The invention is particularly applicable to line telephony and relates to a method and apparatus for converting an isochronous baseband data signal into a diphase signal and vice versa. The diphase transmission is considered as a phase modulation or double-sideband suppressed-carrier in which the modulating signal switches the phase of a carrier whose fundamental frequency in hertz is the same as the modulation rate in bauds. The resulting modulated signal contains fold-over components which are used to advantage by introducing a 90 DEG phase shift between the carrier and base band signals to reduce the line signal level at low frequencies where the line distortion is most severe and enhance the signal level at high frequencies where the attenuation is greatest. The need for line equalisation is therefore reduced.