TRANSMISSION CONSIDERATIONS FOR THE INTRODUCTION OF PCM SYSTEMS INTO TELEPHONE NETWORKS.

This article enumerates the problems that arise when PCM technology is introduced into existing analog telephone networks. It deals in particular with the different transmission characteristics of this technology with regard to 2-wire and 4-wire switching, insertion loss, stability, echoes, noise, and modulation. By observing certain rules for the transition from analog to all-digital operation it is possible to minimize any problems. A strategy is outlined for introducing a combination of PCM switching and transmission technology and selecting the pads necessary for flexible matching to the various types of lines in existing networks.