High-speed transmission of numerical data over telephone channels

Information is transmitted in the form of binary digits; the conversion to and from this form is performed by terminal equipment which adjusts the transmission speed to the characteristics of the channels used. Coding, modulation and conversion of signals at both ends are briefly explained. Experimental transmitter and receiver are described in general terms. Detailed information is provided regarding loaded cable circuits used for experimental transmission. The influence of the transmission channel on the pulse shape is analysed. Results of tests on an artifical circuit equivalent to an unloaded cable circuit are shown.