This video shows one way to use a scope and function generator to measure the length of a piece of coax transmission line as well as estimate its impedance. It uses a "poor man's TDR" type of measurement by launching a pulse into the coax and measuring how long it takes to return after being reflected by the open circuit end. This same technique can be used to determine the distance to a fault (open or short). A simple method for determining the impedance of the line is also shown.

This video touches briefly on transmission line and reflection theory, but is definitely not intended to dive deep into these topics. There are literally books written about this topic so that won't be covered here.

I recently did a video to show how to do this with a simple, low cost squarewave generator instead of using the function generator shown in this video. It can be found here:
   • #88: Cheap and simple TDR using an os...