Time Domain Reflectometry (TDR) has traditionally been performed using a fast oscilloscope and a very sharp impulse or step-type excitation. Reflections from the excitation are measured at the source and distance and the magnitude of the reflection coefficient may be ascertained from the delay and magnitude of the returning reflected signal. This measurement is performed in a very wide band measurement and the signal-to-noise ratio can be quite poor because of this. TDR performed using a Vector Network Analyzer (VNA) allows for the measurement to be made in a narrow RF bandwidth with a corresponding large improvement in signal-to-noise ratio. This method, utilizing the reverse Fourier Transform on a VNA is clearly superior.

This video guides viewers through the process of performing time domain measurements with a vector network analyzer (VNA), using a 2-Port VNA from Copper Mountain Technologies as an example. Presented by Brian Walker, the video walks through the necessary setup for time domain reflectometry (TDR), highlighting the use of a lowpass time domain measurement with a step function, and explaining the purposes of bandpass and impulse functions.

Walker demonstrates how to measure return loss and characteristic impedance across distances and also explores how the VNA can be used for cable fault detection and TDR measurements in practical situations. Key concepts such as the principles of TDR, VNA setup, and cable analysis are thoroughly explained for anyone looking to learn about performing time domain measurements using a network analyzer.