The picturephone® system: Crosstalk considerations in the transmission of analog signals on paired cable

Crosstalk is an important consideration in the transmission of analog baseband Picturephone® signals on paired cable. Crosstalk due to the worst disturbing Picturephone signal can cause a distinctive visible interference pattern. Crosstalk interference from other Picturephone and wide-band systems, such as T1 and T2 digital lines, contributes to random noise. In addition, feedback via crosstalk coupling may cause spurious oscillation of cable equalizers. Methods are determined to control these impairments by placing restrictions on equalizer spacing and cable pair assignment.