NEGATIVE IMPEDANCE TELEPHONE REPEATERS 



1063 



connecting trunks direct to the called subscribers' central offices. It is 

 not economical, however, to provide enough such trunks to handle peak 

 loads. When all of these direct trunks are busy, an incoming toll call is 

 switched to the subscriber's central office via a tandem office serving 

 his general area. Since the losses of trunks between the tandem and 

 local offices are of the same order as those of the direct trunks from toll 

 to local offices, it would be desirable to operate the trunks between the 

 toll and tandem offices at losses close to db if this were practicable. In 

 this way the same transmission objectives would be met on both rout- 

 ings and no contrast in transmission would be evident to the same 

 subscribers on calls completed over the different routes at different times. 

 Fig. 4 illustrates a specific case of 36 trunks between toll office No. 3 





• LOCAL OFFICES 

 TOLL ROUTES 





Fig. 4 — Typical E23 repeater application; Chicago toll tandem trunks. 



