HYDROAKUSTISK KOMMUNIKASJONSUTSTYR FOR SEISMISKE UNDERSOEKELSER TIL SJOES.

摘要

Apparatus and method for transmitting and receiving hydroacoustic pulses used to determine the spatial separations between pairs of such apparatus. According to a preferred embodiment, the apparatus transmits hydroacoustic pulses having a selected shape and frequency at specific times and also determines the time of arrival of received hydroacoustic pulses having a known shape and carrier frequency. Included is a transducer for converting the hydroacoustic energy received from a body of water into electrical energy and for converting electric pulses into hydroacoustic pulses which are then coupled into the body of water. Electric pulses having a selected shape and carrier frequency are digitally synthesized in response to a count comparator. A first electrical transmission path is provided by the apparatus for conducting the electrical pulses from the synthesizer means to the transducer, and a second electrical path is provided for receiving the electrical energy from the transducer and converting the electrical energy into a sequence of digital samples representative of the amplitude of the received electrical energy and consequently of the received hydroacoustic energy. Also included is a detection means which correlates the sequence of digital samples with a set of coefficients representative of the known shape and carrier frequency of the received hydroacoustic pulses. The detection means further computes a sequence of correlation values from the coefficients and selects from these values a group of relative maximum correlation values which indicate the reception of hydroacoustic pulses.