NEW TRANSMISSION MEASURING SYSTEMS 7 



measuring circuits between offices, it is necessary either to have dupli- 

 cate sets of equipment at the two ends of the circuit or to connect 

 two circuits together at one end, testing them at the other end as one 

 circuit. This latter arrangement, while not wholly satisfactory, has 

 been the one generally employed because of the greater expense of the 



Fig. 4 — Latest type of transmission measuring set as used at a switchboard. The 

 associated generator shown in Fig. 5 is usually permanently mounted in the office 

 and testing power is obtained through the multiple as shown. For one-way measure- 

 ments on circuits between offices, the generator is connected to one end of the circuit 

 and the transmission measuring set at the other, both units not being required at 

 each end. 



other method which has involved not only two sets of expensive 

 testing apparatus but two testers, these being necessary because the 

 testing apparatus required frequent adjustment. If circuits between 

 a group of offices in a city are to be tested between circuit terminals 

 rather than by the looping back method, considerable time is con- 

 sumed in traveling between offices when using this apparatus. 



