Underwater depth measurement method with ultrasonic pulse echo timing - using probe with sensor of slowly-varying depth filters for depth sensor and heave compensator

摘要

A signal (10) from a depth sensor attached to the vessel, and the output (12) of a heave compensator are subjected to respective digital low-pass and high-pass filtering (9,11) before addn. (14) to the signal from the echo sounder (6). The latter is delayed (13) by the same amount as the signals passing through the filters (9,11) which areprogrammed by the same microprocessor. The high-pass filter (11) eliminates the low-frequency decay of the integrated signal from the electronically-corrected heave compensator, with deviation of the gyroscopic platform from the horizontal as a consequence of accelerations e.g. during changes of course.