Patent ID: 7417921

Claim:
A method for classifying a type of bottom on a bottom under a liquid, which method comprises the steps of performing an acoustic reflection measurement, in which a first attribute is determined which represents a strength with which acoustic waves are reflected from a location on the bottom through the liquid in a reflection direction; characterized in that the method further comprises the steps of performing an acoustic scattering measurement, in which a second attribute is determined of acoustic waves that are scattered essentially from said location on the bottom; providing a search unit, which contains information with regard to different combinations of the values of the first and second attributes, and associates said combinations with respective bottom types; and identifying a bottom type of said location on the basis of the bottom type which the search unit associates with a combination of the first and second attributes, wherein, the performing the acoustic reflection measurement is performed by a first transmitter transmitting a wave perpendicular from the first transmitter to the bottom and back, and the performing the acoustic scattering measurement is performed by a second transmitter transmitting waves traveling at an angle relative to said perpendicular direction from the second transmitter to the bottom and back.