| 摘要 |
<p>A system for leak detection in underwater structures wherein each critical leakage test point is maintained dry by an enclosure and a test cable is led down through the series of enclosures 22a-22n in fluid-tight manner to support a test probe within the dry test point volume. The test cable 14 is a coaxial cable of selected characteristic impedance and each probe 36a-36n consists of a spirally wound, open-end dual pair supported on a plastic stub so as to constitute a parallel resonant circuit at a selected frequency. Thereafter, a test pulse is conducted down the coaxial cable and the impedance of any probe will be altered by the presence of water to produce a reflected pulse back up the coaxial cable to be detected and input to gating and counting circuitry to determine signal travel duration and, therefore, distance along the cable, as processing, printing and readout components provide output indications. <IMAGE></p> |
