TRANSMISSION FEATURES OF NEW TELEPHONE SETS 359 



Important Transmission Characteristics 

 OF THE New Telephone Sets 

 The specific transmission design features of the new instruments are 

 described elsewhere.^ The purpose here, therefore, is to discuss pri- 

 marily the outstanding improvements in performance resulting from 

 the application of the new instruments and the anti-sidetone feature 

 which has been available for some time. 

 These improvements are 



1. Those due to the station circuit, which, as compared with the 



previous station circuit, 

 a — largely reduce the efficiency of the sidetone path between 



transmitter and receiver without materially affecting the 



electrical efficiency of the set in transmitting or receiving. 



This means that sounds, either noise or speech, which are 



picked up by the transmitter are reproduced in the receiver 



of the same set at a much lower level. 

 b — reduce the susceptiveness for certain types of party line 



sets to interference with reception by noise set up by power 



transmission systems. 



2. Those due to the physical characteristics of the transmitter and 



receiver. 



Fig. 1 — The new handset and deskstand telephone instruments. 



Several of these features have been available for some time and 

 have, of course, been introduced into the plant as they became avail- 

 able. The new transmitter and the anti-sidetone circuit, for example, 

 have been standard for some years and have already been installed in 

 large numbers. 



