Method of measuring the acoustic backscatter property of the floor of bodies of water

Claim 1

A method of measuring an acoustic backscatter property of a floor of a body of water, with the use a ship having vertical and longitudinal axes and moving in a travel direction, wherein a multibeam echosounder is installed on the ship and includes a transmitting and receiving apparatus and a transmitting antenna and a receiving antenna, said a method including: (a) successively exposing a plurality of narrow transmission target strips on the sea floor that extend essentially vertically beneath a center of the transmitting antenna and transversely to the travel direction of the ship to sonic pulses by the transmitting antenna; (b) forming, with the receiving antenna, a fan of narrow receiving strips extending in the travel direction and arranged side-by-side transversely to the travel direction for each transmission target strip, the receiving strips each having a section which covers the associated transmission target strip, of which sections there is a plumb section that lies essentially vertically beneath the center of the receiving antenna; (c) measuring sonic backscatter from the sections of the receiving strips that cover the transmission target strips respectively exposed to a sonic pulse and forming first sonic backscatter values from the measured sonic backscatter; (d) correcting the first sonic backscatter values of said measuring step by: (d)(1) pivoting, at selected points in time, the transmission target strip and the fan of receiving strips respectively by 90° around the vertical axis of the ship from a measuring position into a calibrating position such that the transmission target strip extends essentially vertically beneath the ship along the longitudinal axis of the ship and the receiving strips extend transversely of the longitudinal axis of the ship; (d)(2) measuring sonic backscatter from individual sections of sea floor successively covered by both the transmission target strips and receiving strips defined in said pivoting step and forming second sonic backscatter values corresponding to the individual sections; (d) (3) constructing a calibration curve for each of said plumb sections of the sea floor defined in said measuring step (b) and covered by individual receiving strips during said pivoting step, in which curve the second sonic backscatter values measured from the plumb section in the individual receiving strips are allocated to the respective receiving strips; and (d) (4) correcting the first sonic backscatter values obtained during said measuring step (c) with the calibration curves constructed for each plumb section.

Claim 2

A method of measuring an acoustic backscatter property of a floor of a body of water, with the use a ship having vertical and longitudinal axes and moving in a travel direction, wherein a multibeam echosounder is installed on the ship and includes a transmitting and receiving apparatus and a transmitting antenna and a receiving antenna, said a method including: (a) successively exposing a plurality of narrow transmission target strips on the sea floor that extend essentially vertically beneath a center of the transmitting antenna and transversely to the travel direction of the ship to sonic pulses by the transmitting antenna; (b) forming, with the receiving antenna, a fan of narrow receiving strips extending in the travel direction and arranged side-by-side transversely to the travel direction for each transmission target strip, the receiving strips each having a section which covers the associated transmission target strip, of which sections there is a plumb section that lies essentially vertically beneath the center of the receiving antenna; (c) measuring sonic backscatter from the sections of the receiving strips that cover the transmission target strips respectively exposed to a sonic pulse and forming first sonic backscatter values from the measured sonic backscatter; (d) correcting the first sonic backscatter values of said measuring step by: (d)(1) pivoting, at selected points in time, the transmission target strip and the fan of receiving strips respectively by 90° around the vertical axis of the ship from a measuring position into a calibrating position such that the transmission target strip extends essentially vertically beneath the ship along the longitudinal axis of the ship and the receiving strips extend transversely of the longitudinal axis of the ship; (d)(2) measuring sonic backscatter from individual sections of sea floor successively covered by both the transmission target strips and receiving strips defined in said pivoting step and forming second sonic backscatter values corresponding to the individual sections; (d) (3) constructing a calibration curve for each of said plumb sections of the sea floor defined in said measuring step (b) and covered by individual receiving strips during said pivoting step, in which curve the second sonic backscatter values measured from the plumb section in the individual receiving strips are allocated to the respective receiving strips; and (d) (4) correcting the first sonic backscatter values obtained during said measuring step (c) with the calibration curves constructed for each plumb section.