Improvements in or relating to Methods and Apparatus for Recording the Contour Lines of Topographic Surfaces.

摘要

1,170,955. Echo-sounding. INSTITUT FRANCAIS DU PETROLE, DES CARURANTS ET LUBRIFIANTS. 18 Nov., 1966 [19 Nov., 1965], No. 51725/66. Heading H4D. In an echo-sounding system for the direct recording of contour lines, e.g. of the sea bed, transmitting devices or receiving devices are so spaced that wave interference occurs on transmission or reception, and the spacing and/or the wavelength to which the receiving devices respond is varied during the echo interval to satisfy the relationship where # is the wavelength, h is the spacing, #H is the required contour interval, and r is the slant range of a reflection point, M, producing the echo. In a first embodiment a strip of the sea bed at right-angles to the course of a ship is examined by a side-looking sonar having a transmitter which transmits an acoustic wavetrain at one second intervals. The echo from point M is arranged to be received in phase at a plurality of receivers R for all values of r by varying the receiver geometry during the echo interval. Thus, a number of receiver arrays of different geometry may be connected in turn to an echo-recorder during the echo interval. In a second embodiment the receiver geometry is constant but several ultrasonic frequencies are transmitted simultaneously as a wave-train and the receiving system is made responsive to each frequency in turn during the echo interval, thereby effectively varying # to maintain the required relationship. In a third embodiment both the receiver geometry and # are effectively varied. In a modification, receivers of fixed geometry and transmitters of variable geometry may be employed. When transmitters and receivers are mounted on a curved surface of the ship's hull, compensation for phase delays due to the curvature is provided. It is stated that the invention may also be applied to determining contours of the surface of the earth from an aircraft, using interference of radar beams, or contours of closer objects using laser beams.