| 摘要 |
A method for measuring relatively small water depths is described. Measuring equipment for transmission having a direction in a small angle alpha to the perpendicular of the water depth and for receiving laser pulses of lambda = about 0.5 mu m is used. A first reflection from the water surface is obtained and a second reflection from the bottom. By means of signal processing the signals corresponding to the reflections the water depth is calculated. In particular, the method is characterized in that the signal processing is made in such a way that the function signal-amplitude/time is scanned and a first portion of this function is approximated by a substantially straight first line, after which the function is further scanned to pass through a minimum of its first derivative (inflection point) to a second increasing portion of the function located before a maximum point, which is approximated by a substantially straight second line, whereafter the time interval between the lines that is related to said distance is used for determining it. |
