TYPE-0 CARRIER SYSTEM 



723 



Fig. 38— Test stand. 



their being held during the interval of failure; and second, to make all 

 circuits busy at both terminals, to prevent false seizure by operators or 

 automatic switching equipment. Since many systems may be em- 

 ployed in situations where one terminal is unattended, facilities are 

 included whereby, after failure, the system can be tested from either 

 end, through the use of one of the signaling channels. If it is indicated 

 that the system is operable it can be placed in service again without the 

 necessity of a trip to the unattended terminal. 



SPECIAL SIGNALING FEATURE 



Arrangements are provided by which two circuits can have their E 

 and M signaling control leads interconnected without the use of the 

 signahng converter, which is otherwise required. This feature is employed 

 when two circuits are connected together on a permanent or semi-per- 

 manent basis to form a single trunk. 



TESTING 



To facilitate testing at terminal points a test stand (Fig. 38) has been 

 provided which supports an 0, or N, channel unit during test and 

 adjustment. By a patch cord, the channel unit can be connected to its 

 original framework if desired. Built in pin jacks permit bridging meas- 

 urements to be made at selected points in the transmission circuit. 



