High-Capacity PCM Transmission Systems for Toll Networks

High-capacity pulse code modulation (PCM) transmission systems have made little impact despite the availability of suitable technology and the rapid growth of low-capacity systems. It is shown that high-capacity systems can now be introduced into toll telephony networks without short-term economic or compatibility disadvantages and with considerable long-term advantages. A 120Mbits/s coaxial cable system compatible with 12-MHz systems is described in outline.