TRANSMISSION LOSS DESIGN FOR NON-TELEPHONE SERVICES IN THE TELEPHONE NETWORK.

Listener echo, which arises in multiple 4-wire loop connections, causes error performance impairments in data signal transmission where voiceband modems are employed. This paper first discusses the additive effect of listener echo for single 4-wire loops. Next, a transmission loss allocation method is presented which minimizes impairments under conditions where the total transmission loss at the connections is constant. Furthermore, an application rule for 2-wire metallic lines connecting with 4-wire sections is described which ensures the transmission performance of voiceband modems. It was seen that the most suitable line for toll connections is loaded cable and that loss over subscriber lines connected to digital PBXs must be less than 4. 5 db.