What does the decibel return loss (dBRL) measure on a TDR?

The decibel return loss (dBRL) is a measurement used in time domain reflectometry (TDR) to assess the quality of a transmission line, particularly in identifying cable faults. It quantifies how much of the signal is reflected back due to impedance mismatches or faults along the cable. A higher dBRL value indicates better cable integrity and less reflected signal, which suggests fewer or less severe faults.

By measuring the amount of reflected signal compared to the signal that was transmitted, dBRL provides an understanding of the relative severity of any faults present within the cable. Therefore, when assessing cable performance, particularly in terms of fault detection and maintenance, the significance of return loss cannot be overstated, making option B the correct answer.