What is an electronic instrument used to characterize and locate faults in metallic cables?

The Time Domain Reflectometer (TDR) is an electronic instrument specifically designed for characterizing and locating faults in metallic cables, such as twisted pairs and coaxial lines. It operates by sending a pulse down the cable and measuring the reflections that occur when the pulse encounters any discontinuities or faults, such as breaks, shorts, or changes in impedance. By analyzing the time it takes for the reflections to return, the TDR can determine the distance to the fault, allowing technicians to accurately pinpoint issues within the cable.

This capability makes the TDR invaluable in maintaining and troubleshooting communication infrastructure, ensuring that faults can be located quickly and accurately. Other instruments listed, such as a digital multimeter, oscilloscope, and signal generator, are useful for various electrical measurements and analysis, but they do not possess the focused functionality for fault location in cables that a TDR provides.