| 摘要 |
A system for sonically probing a seabed comprises at least one row (14, 100) of transducers (22, T1, T2, TZ) that each can produce a sonic beam, and a corresponding row of sonic detectors (24, D1, D2). Each transducer is independently energized to produce a narrow sonic beam (40), with resulting seabed or subsea echoes being detected to produce one pixel of a display (60 , 80, 90, 150) formed by an X-Y array of pixels, before a next transducer is energized and its echoes are detected to produce another pixel of the displa y. When the system detects a large change in echo amplitude at adjacent seab ed locations, then scanning at those locations is accentuated by analysis and b y additional sonification at different frequencies. The transducers are closel y spaced, at a center-to-center distance (G) of typically about 3.5 cm, to provide good horizontal resolution. Each transducer is energized to produce a sonic pulse which, dependent on the application, has a carrier frequency (32) such as 2mHz, 1 mHz, 500kHz or 100kHz. This results in an optimized narrow sonic beam, with each pulse having a duration (A) on the order of 10 to 100 microseconds to produce a modulation frequency on the order of 200kHz to 5Khz, and with each pulse having a high maximum energy to create a wide frequency bandwidth in the seabed.
|
