Subjective and Objective Quality Evaluation Study of BPL-PLC Wired Medium

This paper presents results of research on the effectiveness of bi-directional voice transmission in a 6 kV mine cable network using BPL-PLC (Broadband over Power Line - Power Line Communication) technology. It concerns both emergency cable state (supply outage with cable shorted at both ends) and loaded with distorted current waveforms. The narrowband (0.5 MHz–15 MHz) and broadband (two different modes, frequency range of 3 MHz–7.5 MHz) transmission efficiency, considered as an objective study, was correlated with the level of noise in the cable for both induction-inductive and mixed capacitive-inductive coupling of the measurement devices and/or modems. The quality of voice transmission, considered as a subjective study, was assessed by a group of 15 people aged between 25 and 35 years old. The test audio signals included samples in 3 languages sourced from ITU (International Telecommunication Union) and processed in 3 bitrates ranging from 8 kbps to 24 kbps.