| 摘要 |
<p>A method of identifying and locating an underwater acoustic reflector having a shell surrounding a core by identifying if an object reflects a sonar interrogation of a search area with a double echo, measuring the separation of the two echoes, target strength of each echo, total target strength, acoustic width, frequency response and phase response of the object, which is accepted or rejected as being of interest if it matches known characteristics of an underwater acoustic reflector, such as minimum values. Acoustic diameter may be measured and compared to known diameters for acoustic reflectors within the search area. These steps may be carried out sequentially and/or in parallel. Objects may be measured with short pulses interspersed with long pulses that alternate between different frequencies and repeated three times, each from a different aspect. The second echo should be stronger than the first echo. An absolute position of the acoustic reflector in relation to the sonar receiver may be combined with the absolute GPS position of the sonar receiver to plot an absolute position of the acoustic reflector. Several reflectors may be attached to an oil pipeline and the pipeline route plotted.</p> |
