AUTOMATIC TESTING OF INTEETOLL TRUNKS 929 



In both the manual and semi-automatic methods of measurement, the 

 results must be recorded manually. For statistical analysis of trunk 

 transmission performance in terms of "bias" and "distribution grade", 

 as discussed in the companion paper,* deviations of the measured losses 

 from the respective specified losses must be computed and summarized 

 manually. 



The automatic testing equipment described in this paper has been 

 developed as an additional maintenance tool. It will not supplant exist- 

 ing arrangements discussed above but rather is intended to increase the 

 capabilities of plant personnel to do an effective maintenance job. The 

 following features of the equipment contribute particularly to this end: 



1. Large numbers of trunks can be tested and the results recorded 

 without the continuous attention of a testboard attendant. 



2. The attendant is informed by an alarm whenever the loss of a 

 trunk deviates excessively from the specified value. 



3. Computation and summarizing of net loss deviations into class 

 intervals are done automatically, thus facilitating statistical analysis of 

 trunk performance. 



4. Data can be collected quickly in large volume for indicating the 

 performance of groups of trunks. Confusion occurring with manual 

 measurements because of changing conditions with time is reduced. 



5. Stability of an individual trunk may be checked by a series of 

 repetitive tests. 



6. Semi-automatic two-way trunk tests can be made by one attendant 

 when required. 



To do an equivalent job entirely by manual methods would require 

 an appreciable increase in the amount of manual test equipment and in 

 the number of test personnel. A comparison of the times required for 

 operational and transmission tests by manual, semi-automatic and auto- 

 matic methods is shown in Fig. 1. The time shown for the code 102 test 

 does not include coordination time required if information on test re- 

 sults in both directions is required at one end. 



GENERAL DESCRIPTION OF AUTOMATIC TESTING EQUIPMENT 



Automatic intertoll trunk testing requires automatic equipment at 

 both ends of the trunk.At the originating or control end, an automatic 

 test circuit sets up the test call and controls the various test features. In 

 the distant offices, test lines reached through the switching train provide 

 appropriate automatic test terminations. The automatic equipment for 



* H. H. Felder and E. N. Little, Intertoll Trunk Net Loss Maintenance Under 

 Operator Distance and Direct Distance Dialing, page 955 of this issue. 



