I'm sorry folks but you must be dealing with those new fangled ground rods that are TDR friendly. I always used those old copper ones that get buried in the ground most of the way. Those new, TDR friendly ones have consistant electrical insulation all the way down the length to the bare end where the electrical pulse hits the change of impedance and some gets reflected back.
TDRs are wonderful things but you can't use them for everything. But let's say you could. We still would have to set the velocity of propagation dial to match the cable. I'm used to 66% for polyethlene <sp?> and 78% for cellular PE or foam. The VP for ground rod/dirt would vary widely over soil & moisture conditions. So if you could get a reading, the margin of error could easily be > the length of a gtound rod.
OTDRs are a joy to play with. ETDRs with coax are still OK. ETDRs with non-paired cables, GOOD LUCK! If you're trying to do a SWAG over which manhole , 100's of feet apart, Maybe.
This is just the collision of my optimism and personal experience.
Joe
