Power-line carrier telephony

The inherent advantages of carrier-current telephony over high-voltage power transmission lines during the past five years have resulted in an unusually rapid development of this form of communication. To one who has not been constantly in touch with this rapid development, the necessity for the numerous types of carrier-current telephone equipment now available is not always apparent. This paper gives a brief outline of modern communication requirements in this field, the problems involved in providing this communication, and a brief outline of the different types of equipment now available to provide the required communication.