24-Type testing equipment for telephone subscriber loops

A new transmission measuring system has been developed for the testing of telephone subscriber loops. It consists of an electronically swept oscillator located at the central office and a small measuring set called the ¿loop checker¿ used at the subscriber´s location. The user sets the loop length information into the loop checker, and with another adjustment the set takes the loop resistance into account. The measurement results in a direct pass-fail judgment of the transmission quality. Companion papers cover the engineering aspects of loop transmission and the results of field tests of the new equipments.1,2