Automatic equipment for final testing of telephone pair gain systems

This paper describes a practical solution of final testing of digital subscriber pair gain (DSPG) systems. These devices help to overcome the last-mile bottleneck of telecommunication networks. DSPG systems must comply with rigorous regulations of national communications administrations to be permitted in public use. The architecture of the system consists of a custom measuring unit, switching network and a supervisory PC. An artificial telephone line has been developed to simulate UTP cables for lengths of 3.5 and 4 km. Total harmonic distortion (THD) of the ringing signal is measured with a microcontroller using a method that is explained in detail.