Abstract: A method for measuring a contour of the ground by means of a transmitting arrangement for the directed emission of sound signals and by means of a receiving arrangement including at least two transducers for receiving the sound signals reflected from the contour of the ground. Sound signals are emitted consecutively using a plurality of N soundings from predetermined positions P1, P2, P3, P4, . . . , PN having different aspect angles ?N in relation to and distances rN from the contour of the ground. A phase difference, the path differences resulting therefrom, the corresponding angles of incidence, and the coordinates of incidence are ascertained from the receive signals of the transducers for a plurality of sampling times and for the N soundings. Afterwards, the data density is ascertained within a predefined range containing the coordinate of incidence.

Abstract: A method for measuring a profile of the ground involves using a transmitting arrangement, which is attached to a watercraft, for the directed emission of sound signals into an underwater area and a receiving arrangement having at least two transducers for receiving sound waves reflected by the profile of the ground.

Abstract: A method for measuring a profile of the ground involves using a transmitting arrangement, which is attached to a watercraft, for the directed emission of sound signals into an underwater area and a receiving arrangement having at least two transducers for receiving sound waves reflected by the profile of the ground.

Abstract: A method for measuring a contour of the ground by means of a transmitting arrangement for the directed emission of sound signals and by means of a receiving arrangement including at least two transducers for receiving the sound signals reflected from the contour of the ground. Sound signals are emitted consecutively using a plurality of N soundings from predetermined positions P1, P2, P3, P4, . . . , PN having different aspect angles ?N in relation to and distances rN from the contour of the ground. A phase difference, the path differences resulting therefrom, the corresponding angles of incidence, and the coordinates of incidence are ascertained from the receive signals of the transducers for a plurality of sampling times and for the N soundings. Afterwards, the data density is ascertained within a predefined range containing the coordinate of incidence.

Abstract: A method and apparatus for determination of a Doppler frequency shift 30 between a transmitted signal 4 and a received signal 20 resulting from this transmitted signal. A plurality of relative frequency shifts are carried out, in each case by a real frequency shift value, in that either at least one shifted discrete amplitude spectrum 8 of the transmitted signal 4 and at least one shifted discrete amplitude spectrum 22 of the received signal 20, or a plurality of shifted amplitude spectra of the transmitted signal 4 or of the received signal 20 are produced. Quality measures are determined for these frequency shifts, indicating the quality of the match between the shifted signals. That quality measure which corresponds to the highest quality of the match is determined, and the frequency shift value associated with this quality measure is equated to the Doppler frequency shift 30 to be determined.

Abstract: A method is provided for measuring the acoustic backscatter property of the floor of a body of water in which an acoustic multibeam echosounder employed on a ship is used to measure the sonic backscattered from a narrow transmission target strip on the sea floor that extends essentially vertically beneath the center of the transmitting antenna, transversely to the travel direction of the ship and which is successively exposed to sonic pulses by the transmitting apparatus. The measured backscatter is converted into sonic backscatter values allocated to receiving strips (115) of the multibeam echosounder. Calibration curves are constructed for all floor elements along the course line of the ship by echosounder measurements during a calibrating operation following a 90.degree. pivot of the echosounder around the vertical axis of the ship.

Abstract: For mapping and exploring bodies of water, fan depth finders are used that emit ultrasound pulses and receive-echo pulses in a number of tightly-bundled receiving sectors. Because the predominant number of receiving directions is oriented diagonally downward instead of straight down, these ultrasound pulses propagate on bent paths due to sound refraction. Sound refraction is caused by different sound velocity layers, the precise knowledge of which is necessary for determining an average sound velocity. The method of the present invention does not require a separate measuring probe to measure the sound velocity at different depths; rather, the average sound velocity is determined using a regression method based on the travel time measurements of the ultrasound pulses. In this method, first the floor profile that forms the basis of the measured travel times is determined with an assumed average sound velocity and compared with a floor profile model composed of partial functions modeled in a specific manner.