Aside from the things camperbob identified, this is pretty neat. The tricky parts are getting the pulse generator right (you want a sharp leading edge and flat

Aside from the things camperbob identified, this is pretty neat. The tricky parts are getting the pulse generator right (you want a sharp leading edge and flat top, with no ringing) and having an oscilloscope with a flat response well into the GHz range. One solution to the second challenge is to home-brew a sampling adapter, like this one from 2000[1]. This is a good fit for TDR because of two factors inherent in the TDR process: a) it is repetitive, so the usual drawbacks to "sub-nyquist" sampling don't apply; and b) you have ready access to a pre-trigger, so it is easy to see the leading edge of the signal of interest. The first challenge requires a lot of cleverness or access to expensive test equipment. [1] http://electronicdesign.com/boards/1-ghz-sampling-oscilloscope-front-end-easily-modified http://electronicdesign.com/boards/1-ghz-sampling-oscillosco...