# Time-domain reflectometry ( reflection coefficient-resistive load)

## Description

Time-domain reflectometry or TDR is a measurement technique used to determine the characteristics of electrical lines by observing reflected waveforms. A time-domain reflectometer is an electronic instrument that uses time-domain reflectometry to characterize and locate faults in metallic cables. The TDR analysis begins with the propagation of a step or impulse of energy into a system and the subsequent observation of the energy reflected by the system. By analyzing the magnitude, duration and shape of the reflected waveform, the nature of the impedance variation in the transmission system can be determined. If a pure resistive load is placed on the output of the reflectometer and a step signal is applied, a step signal is observed on the display, and its height is a function of the resistance. The magnitude of the step produced by the resistive load may be expressed as a fraction of the input signal.

Related formulas## Variables

ρ | Reflection coefficient (dimensionless) |

R_{L} | Resistance (ohm) |

Z_{0} | The characteristic impedance of the transmission line (ohm) |