AUTOMATIC TESTING OF INTERTOLL TRUNKS 951 



when the loss of an intertoll trunk deviates an abnormal amount from 

 its specified value. The maintenance practices currently require that, 

 Avhenever an intertoll trimk is found to have a deviation of ±5 db or 

 more in either direction, the trunk should be removed from service im- 

 mediately and the cause of the abnormal deviation corrected. Accord- 

 ingly, the computer circuit includes an alarm feature which sounds 

 an alarm to attract the immediate attention of the attendant whenever 

 the computed deviation is ±5.0 db or greater. 



The maintenance forces may also like to know promptly about trunks 

 with wide deviations but which are not so bad as to recjuire immediate 

 remo\-al from service. For this purpose the computer also includes a 

 limit checking feature. This can be set, by means of optional wiring, to 

 detect deviations in excess of dz3.0 db, dz4.0 db or ±5.0 db. Whenever 

 a deviation exceeds the limit for which the computer is wired, this 

 feature performs as follows: 



(1) When the Teletypewriter is not in operation the test frame stops 

 and sounds an alarm. 



(2) When the Teletypewriter is recording all measurements, the 

 letter U is added in a separate column at the end of the test record. The 

 letter stands out on the record to j^ermit fiuick spotting of trunks wdth 

 abnormal deviations. 



(3) By means of a control key, a transmission test record can be 

 printed only for those trunks whose deviation exceeds the computer 

 checking limit or which are "noisy" at either end. 



Teletypewriter Record 



The Teletypewriter is put into operation by means of a key on the 

 test frame. When this key is normal, no records are printed. Under this 

 condition a trouble causes the test frame to stop and sound an alarm. 

 When the Teletypewriter is operating it prints various records and a mi- 

 nor operational trouble may result only in a record, without an alarm. 

 Each record occupies a separate line on the tape. Each line starts wdth the 

 four-digit trunk identification number in the first column. Fig. 7 shows a 

 short specimen of the the Teletypewriter record. 



When the pass busy key on the test frame is in its nonoperated posi- 

 tion, the Teletypewriter will print the trunk identification number, fol- 

 lowed by the letter B, for each trunk passed over without test because it 

 was busy. This is done on both operational and transmission test cycles. 

 When the pass busy key is operated no record is made of busy trunks 

 passed without test. 



During operational tests no record is printed for trunks which are 



