Patent Document ID: 9702973
Application ID: 14647356
Patent Flag: 1

Claim One:
1. An environment measurement system comprising a first unit, the first unit including: a transmission unit which is located undersea and transmits an acoustic wave in a designated direction a plurality of times; a first reception unit which is located undersea and receives the acoustic wave reflected by a reflecting body at the sea surface or the seabed; a transmission direction setting unit which designates, to the transmission unit, transmission directions specified in advance by a user, so as to cause the transmission unit to transmit acoustic waves in the directions; a first necessary time measurement unit which, for each of the transmission directions, measures from transmission and reception times of the acoustic wave a time necessary for the acoustic wave to return, as a necessary time, and outputs an average of the measured necessary time as an average necessary time for each of the transmission directions; a layer setting unit which partitions between the sea surface and the seabed into layers each extending horizontally, at intervals of preset distances; a simultaneous equations set-up unit which sets up simultaneous equations using the transmission directions, the necessary times and the layer thicknesses and taking average sound velocities in the respective layers as unknown variables; a simultaneous equations solving unit which solves the simultaneous equations; an initial parameter setting unit which sets initial values necessary for the simultaneous equations solving unit to solve the simultaneous equations, as parameter initial values; a sound velocity profile output unit which creates a profile of sound velocities by determining solutions acquired by the simultaneous equations solving unit to be average sound velocities in the respective layers and arranging the average sound velocities in the respective layers in order of depth, and outputs the profile; a map holding unit which holds a seabed map including at least unevenness of the seabed as depth information; and a matching unit which derives seabed depths on the basis of the average necessary times for the respective transmission directions, corrects the seabed depths by unit of matching between the seabed depths and the seabed map, derives from which point of the seabed depths the acoustic wave is reflected, for each of the transmission directions, and thereby acquires corrected reflection depths, wherein the layer setting unit partitions between the sea surface and the seabed on the basis of the corrected reflection depths, where layer partitioning down to the smallest depth is performed at intervals of predetermined thicknesses, and layer setting from the smallest depth to the largest depth is performed on the basis of the reflection depths, allowing the number of layers and layer thicknesses to become different for different ones of the transmission directions.