36 



Hr.l.L SYSTEM TECHMC.IL JOiliX.-tL 



period of Inmi iwn li. four woi-ks. thvu ami (uic-half 8-liour days per 

 week assumed; any trouble fouiui being cleared as the testing work 

 is done. The niainteiiaiue of the subscribers' lines is not included 

 in this work since it is taken care of by other methods as outlined 

 later. 



In oriler to gi\e a general picture <jf the application of transmission 

 testing in the exchange telephone plant, a brief discussion of ttu 

 methcxls enii)lo\ed in both manual anil machine switching systems 

 is gi\en IkIow . In either system the loop method of testing proves 



I 



I'K- 



-lllustratiun uf 



.^.\ Transmission Measuring Set Iking Operated in a 

 Manual Office 



most satisfactory, that is, one measuring set is used and where both 

 terminids of a circuit are available as in cord circuits, a loop test 

 through the circuit is made. In testing trunk circuits two trunks 

 are l<Ki[x?d together at their distant terminals and a measurement 

 maile on the two combined. 



Transmission I'csis on .\finiii<il Kxcluiitt^f Area Circuits. In central 

 office, F'. H. X. and toll switchbo,irds, the cord circuits and associated 

 o(K'rators' circuits are tested by u.sing a portable transmission measur- 

 ing set. moving this along thelioards as required to jiick up the cords. 

 Kig. 7 sliiiux .1 :{. \ transmission measuring set being operated at an 



