34 



BELL SYSTEM TECHNICAL JOURNAL 



Fig. 12 is a record of the l.OOO-cycle loss of a long four- wire cable cir- 

 cuit which was removed from service for purposes of trouble loca- 

 tion. The small jogs in the curve were caused by the normal 

 functioning of the automatic transmission regulators. The sudden 

 change occurring at 8:50 a.m. was due to a trouble which momen- 

 tarily decreased the transmission loss. The other large jog in the 

 record was caused by an attendant making a routine adjustment. 

 Evidently a trouble condition can not only be detected but located 



Fig. 12- 



-Transmlssion loss — time record made on long four-wire cable 

 circuit while locating a trouble. 



by connecting transmission recorders at a number of different points 

 along a circuit and making simultaneous records. 



Transmission-frequency measurements on circuits and repeaters can 

 be made with the recording system in less than one-tenth the time 

 required with manually operated measuring apparatus. When the 

 system has been completely developed and applied generally in the 

 field, material time savings should result, particularly in the larger 

 offices. Also, it is to be expected that the continuous records obtained 

 with the recorders as compared to measurements at only a few points 

 with manually operated apparatus will materially assist in disclosing 

 abnormal circuit conditions. 



