| 摘要 |
<p>PURPOSE:To enable the efficient employment of a memory in a data recorder, by conducting logging for a certain time and at a prescribed time interval by a clock in a towing unit. CONSTITUTION:On the occasion of investigation of a seabed structure, a deep- sea towing unit 3 positioned in the vicinity of the seabed is so set as to conduct logging for a data recorder 6 for a prescribed time and at a prescribed time interval without depending on an external signal. On a towing ship 1, on the other side, measurement of a distance between the ship and the towing unit 3 is executed. Based on the measured distance and in consideration of a time required for an acoustic wave to reach the towing unit 3, a sound source is oscillated so that the acoustic wave can reach the towing unit 3 just after the start of the logging. As the result, a direct wave (first wave) reaches the towing unit 3 just as the time point when data recording is started. Together with the direct wave, reflection waves reflected on the seabed 5 and a part below the seabed and returned are detected by a hydrophone 8, and necessary data are recorded in the data recorder 6.</p> |
