Anderson, A.L., D. S. Bailey. and R. J. Korinek. 1989.
Leak Detector and Locator Utilizing Time Domain Reflectometry and Sampling Techniques.
U. S. Patent No. 4,797,621.
(posted July 26, 1996)

A leak detector and locator utilizes an electrical cable disposed in proximity to fluid carrying pipes or other area wherein a leak may occur.  Pulses are applied to the cable and the reflected waveform is analyzed to detect changes in the characteristic impedance of the cable caused by fluid penetrating the insulation of the cable. A different portion of the waveform corresponding to a different point on the cable is sampled after each pulse is generated and stored until the entire waveform has been sampled and stored. Subsequent samples of the waveform are compared with the stored waveform and a leak is indicated if the subsequently sampled waveform differs from the stored waveform by a predetermined amount.