Performance Analysis and Design Guidelines for Multiple Four-Wire Path Telephone Connections

In this paper the listener echo performance of telephone network connections with more than one four-wire path is considered. The objective is to obtain simple design guidelines for the application of four-wire transmission and switching technologies, such that satisfactory listener echo performance for voice and voiceband data services is achieved. The performance analysis is based on a simple but accurate approximation of the overall connection frequency response. The amplitude response of each connection component is uniform. The general case of nonidentical four-wire paths and nonidentical interconnecting twowire paths is considered. Results are presented for: . the overall connection stability margin, and conditions for connection stability, . the condition for satisfactory connection performance, and . the relative merits of allocating required increases in connection stability margin to return losses, and to four-wire and two-wire path losses. A practical example illustrates the results.