526 BELL SYSTEM TECHNICAL JOURNAL 



Conference Connections 



The teletypewriter exchange system provides a means whereby 

 practically unlimited numbers of stations can be connected in con- 

 ference connections. Figure 14 shows a typical conference connection. 

 Each link in the conference circuit is provided with a simple repeater, 

 each of which is equipped for breaking. In this manner to and fro 

 communication by the half-duplex method operation can be attained. 

 The conference repeater circuits are made up in groups of five or ten, 

 each of which is equipped with a multiple appearance so that all 

 operators have access to the repeaters. 



O SWITCHBOARD 

 O SUBSCRIBER 



Fig. 14 — Typical conference connection. 



Regenerative Repeaters 



It is necessary in some long circuits to improve transmission by 

 inserting a regenerative repeater in the circuit. To make this possible 

 and easily performed by any operator, regenerative repeaters are 

 provided with a complete jack multiple appearing before all operators. 

 Both ends of the repeater are available in this multiple and the repeater 

 may be inserted where the transmission equivalent of the circuit 

 involved makes it necessary. 



Typical Built-Up Connection 



In order to provide TWX service on a nationwide basis, certain of 

 the connections require one or more intermediate switchboards so 

 that one or more through operators may be involved. As an illustra- 

 tion of this Fig. 15 shows a connection established between a calling 

 station in New York and a called station in San Francisco with a 

 through switch at Chicago, a method used when all direct trunks are 

 busy. This figure shows the manner in which the TWX equipment 



