Practises in Telephone Transmission 

 Maintenance Work 



Bv W. H HARDEN 



W 



Synopsis: This imikt (IfstriUi. the prailk-al appliralions of transmission 

 nuiinlrnanrc nu-thmls in a lelcphone system. Tho nu-thmls applirable to 

 toll cinuils of vaiious ty|K-s an- first <li«uss<.-<l, information JK-ing included 

 in tfiif conniition on ihr niainti-nanif of the amplifier circuits involved in 

 telephone rejieaters and carrier. Testing methods applicable to the local 

 or exchange area (ilant arc next desirilietl. the destription including both 

 manual and machine switching systems. 'I"he results accom|)lished in 

 toll anil local transmission maintenance work arc considered from the 

 standixiint of the kinils of trouble which can be clin)inatc<l and the effect 

 which thi-se troubles have on service. 



The metho<is descrilietl in the main Inxly of the pa|)or relate particularly 

 to tests of volume efhciency. Certain other transmission maintenance 

 testing methotls dirivtly as.s<iciate<l with volume efliciency tests are briefly 

 descril>etl in .\p|>endi\ \ of the pa|K-r. 



IT is the purixise df litis paper to present a neiieral |)iilure i>t the 

 practical applications of inelhrKls of nieasurinj; transmission 

 efticiency in the Bell S\stein which have iteen developed by study 

 and exfK-rience under plant o|K'ratinn conditions. The rapid growth 

 of the telephone industry has made it necessary that these niethtKls 

 be such as to allow them to be applied on a large scale in a sys- 

 tematic and economical manner tliereb\- [iroNiding for a tpiick 

 (x-ritKlic check of the el1icienc\- of the variotis t\|)es of circuits as 

 ihcy are usc-<l in se.rvice. 



Transmission maintenance can l>e broadK' detinetl as that mainten- 

 ance work which isdirectetl primarily towartis instiring that the talking 

 elViciencies of the telephone circuits are those for which the circuits are 

 designitl. There are, of coursi>, many elements which afTect the talking 

 efticiency and various d-c. and a-c. tests are available for checking the 

 electrical characteristics of circuits ami equipment to insure that these 

 characteristics are ln-ing maintained in accordance with the proper 

 standards. In the final analysis, however, an overall test of the trans- 

 mission et>icienc\ of the circuit in the condition it is used in service 

 will show at once whether it is giving the loss, or in the case of ampli- 

 fier circuits, the gain which it should give. Transmission tests, 

 theref(»re, offer .i means whereby main- of the electrical characteristics 

 of circuits can lie tjuickly .ind accurateh checked. 



In referring to transmission testing apparattis in this paper, four 



si.indard l> jks deMriU-d in pre\ious pajnTs are involved. The first 



ihri-e iy|R-s listed lielow were descrilx-d by Best and the fourth by 



'V.i]trT i>rc»?nlc«l at the P.uilir Cojst Convention, .1. T. E. E., October l')24- 

 aUltiictcd in tfir Journal, .1. /. E. E., Vol. 43, p. 1124, 1924. 



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