Andrews, J.R. 1994.
Time Domain Reflectometry.
Proceedings of the Symposium on Time Domain Reflectometry in Environmental, Infrastructure, and Mining Applications, Evanston, Illinois, Sept 7-9, U.S. Bureau of Mines, Special Publication SP 19-94, NTIS PB95-105789, pp.4-13
(posted September 23, 1996)

Time Domain Reflectometry, or TDR, is an electrical measurement technique that has been used for many years to determine the spatial location and nature of various objects. An early form of TDR was radar. This paper discusses the principles of TDR with an emphasis on TDR within coaxial transmission lines. Since the 1960's, the major oscilloscope companies have all built dedicated TDR instruments or oscilloscopes that include TDR capabilities. By the late 60's, instruments were available which had 35 ps risetime capabilities. Many of these older instruments with risetimes from 1 ns to 35 ps have been discontinued, but are still available, relatively inexpensively, on the used equipment market. The TDR instruments built today by the oscilloscope companies are completely digital, programmable instruments with many features. There are also several smaller companies making specialized TDR instruments. A review is made of very fast (<200 ps) coaxial TDR instruments commercially available from Iwatsu, Le-Croy, HYPERLABS, Tektronix, Hewlett-Packard and Picosecond Pulse Labs.