30-CHANNEL PCM TERMINAL EQUIPMENT IN THE M5 CONSTRUCTION PRACTICE.

The previous LM Ericsson PCM system, which consisted of the 30-channel PCM terminal ZAK 30/32-2 and the 2. 048 Mbit/s line equipment ZAD 2, was based on the CCITT recommendations applicable at that time and the earlier M4 mechanical construction. A new version of the first-order PCM multiplex equipment ZAK 1/30-3, together with a number of signaling converters, have now been developed based on the new M5 mechanical construction for transmission equipment, new international specifications, and taking into account the progress in component and circuit engineering and the experience gained from LME's large-scale installation of PCM equipment. The main features of the new PCM terminal equipment are compactness, concentration of functions to a few types of units, interface flexibility, centralized maintenance and better performance than that required by the latest CCITT and CEPT recommendations. ZAK 1/30-3, in the M5 mechanical design, is the first member of a PCM family that will eventually comprise PCM line equipment and digital multiplex equipment. The use of standardized interfaces simplifies interconnection with existing PCM equipment.