952 



THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1956 



satisfactory. Troubles during either operational or transmission test 

 cycles result in a record of the trunk identification number followed by a 

 cue letter in a separate column denoting the nature of the trouble. This 

 may be a single line record or a double line record for a repeat test on the 

 same trunk as previously discussed. For example, in Fig. 7, the letter Y 

 in the second line indicates that on trunk 1267 the far end was unable 

 to complete its transmission measurement successfully. The letter A in 

 lines 3 and 4 indicates that the test frame was unable to establish a con- 

 nection over trunk 1293 on either its first or second attempt. The record 

 of transmission tests is printed in several columns. Reading from left 

 to right (see Fig. 7) these are (1) trunk identification number, (2) speci- 

 fied net loss, (3) deviation in the far-to-near direction together with the 

 sign, and (4) deviation in the near-to-far direction together with the 

 sign. In columns 2, 3, and 4 the decimal points are omitted and the 

 ten's digits are omitted when they are zero (0). Column 5 will contain 

 an N if the far end is "noisy" or the letter U if the deviation in the far-to- 

 near direction exceeds the computer check limits, preference being given 

 to N if both conditions occur on the same trunk. Likewise column 6 

 contains an N if the near end is "noisy" or a U if the deviation in the 

 near-to-far direction exceeds the computer check limits. Transmission 

 test cycles will, of course, include a trouble record whenever an opera- 

 tional trouble is encountered or whenever the transmission test cannot 

 be completed successfully. 



Fig. 7 — Teletypewriter test record. 



