Method and apparatus for computing and displaying sound rays of a sonar system

Claim 1

In a method for computing and displaying sound ray paths of a sonar system by an analog computing method, the improvement comprising the steps of, a. computing transmission loss (Nw) of sound waves at the same time as the computation of sound ray path, b. setting the value of a Figure of merit (NFM) of the sonar system c. comparing said transmission loss (Nw) with the value of a figure of merit (NFM) of the sonar system, and d. displaying the computed sound ray paths on a display unit discriminating the sound ray paths within the detection range of the sonar system where transmission loss (Nw) is equal to or smaller than the value of a figure of merit (NFM) from the sound ray paths out of the detection range of the sonar system where transmission loss (Nw) is larger than the value of a figure of merit (NFM).

Claim 8

An apparatus for analyzing and displaying sound ray paths, comprising an analog type ray path analyzer (A), a display unit (B), and a detection range unit (C), said detection range unit comprising a. means for computing propagation distance S from sound velocity C by the equation (S Integral Cdt); b. means for computing free transmission loss and absorption loss by sea-water by the equation (10 log S + 0.01f2S), where f is sound frequency; c. means for computing sea-surface reflection loss by the equation ( Beta Ns), where Beta is reflection loss at sea level and Ns is the number of reflection times at sea level from the source to the distance S; d. means for computing sea-bottom reflection loss by the equation ( gamma Nb), where gamma is reflection loss at sea bottom, and Nb is the number of reflection times at sea bottom from the source to the distance S; e. an adder for obtaining the analog value (10 log S + 0.01f2S + Beta Ns + gamma Nb); f. means for comparing the output of said adder with the value of a figure of merit NFM, and providing the output signal when the former exceeds the latter; and g. a modulator for modulating the intensity of said display unit according to the output of said comparison means, said display unit being connected to receive inputs from said analog type ray path analyzer and said modulator, and said detection range unit (C) being connected to receive inputs from said analog type ray path analyzer.

Claim 9

An apparatus for analyzing and displaying sound ray paths, comprising an analog type ray path analyzer (A), a display unit (B), and a detection range unit (C), said detection range unit comprising a. means for computing propagation distance S from sound velocity C by the equation (S Integral Cdt); b. means for computing free transmission loss and absorption loss by sea-water by the equation (10 log S + 0.01f2S), where f is sound frequency; c. means for computing sea-surface reflection loss by the equation ( Beta Ns), where Beta is reflection loss at sea level and Ns is the number of reflection times at sea level from the source to the distance S; d. means for computing sea-bottom reflection loss by the equation ( gamma Nb), where gamma is reflection loss at sea bottom, and Nb is the number of reflection times at sea bottom from the source to the distance S; e. an adder for obtaining the analog value (10 log S + 0.01f2S + Beta Ns + gamma Nb); f. means for comparing the output of said adder with the value of a figure of merit NFM, and providing the output signal when the former exceeds the latter; and g. a modulator for modulating the intensity of said display unit according to the output of said comparison means, said display unit being connected to receive inputs from said analog type ray path analyzer and said modulator, and said detection range unit (C) being connected to receive inputs from said analog type ray path analyzer.