I was wondering if anyone knows how some of the handheld testing devices, like the (Fluke NetTool or now, the Linkrunner series http://www.flukenetworks.com/enterpr...rk-Auto-Tester ) test cable length? On the older NetTool device, I find the measurement helpful, but not extremely accurate. For instance, on a 14.1 feet, I get a measurement of 16 feet with the NetTool. This is close enough for me, to help figure out where old wiring on a 36 acre facility goes. Just wondering how they do it.