954 THE BELL SYSTEM TEC?IXICAL JOURNAL, JULY 1956 



trunks from other toll offices can be tested on a semi-automatic basis 

 from the toll test board in the distant office. 



Fig. 8 shows a possible application of automatic test circuits. In such 

 an application, all No. 4 type toll crossbar offices would have both near- 

 end and far-end equipments. Other offices would have far-end equipment 

 only when they have a sufficient number of direct trunks to No. 4 type 

 offices to justify its use. The several types of tests which would be pos- 

 sible are indicated in the illustration. 



It can be seen that a well distributed number of near-end and far-end 

 test circuits will make it possible to test automatically a large percentage 

 of the intertoll trunks throughout the country. This is particularly true 

 in the more populous sections, where the concentration of trunks results 

 in the probability of toll centers having trunks to more than one office 

 furnished with near-end equipment. 



ACKNOWLEDGMENTS 



Automatic intertoll trunk testing arrangements, including transmis- 

 sion tests, are the result of the ideas, efforts and experiences of many 

 people concerned with intertoll switching and maintenance problems 

 throughout the Bell System. Mr. L. L. Glezen and Mr. L. F. Howard 

 deserve particular mention in this regard. Specific credit should also be 

 given to Mr. B. McKim and Mr. T. H. Neely for the basic scheme of 

 two-way transmission measurements and accuracy checks and to Mr. 

 C. C. Fleming for the design of the amplifier and amplifier-rectifier. 

 Appreciation is given to various departments of the American Tele- 

 phone and Telegraph Company for their assistance during the develop- 

 ment and trial of this equipment. Mention should also be made of the 

 hearty cooperation and aid given by the A.T. & T. and Associated 

 Company plant forces during the field trial of automatic transmission 

 testing. 





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