Optimal frequency in acoustic location

The choice of operating frequency in acoustic location is highly problematic and is found by compromise. From the one side, the frequency should be as higher as possible so that to achieve the high accuracy and directivity. From the other side, the lower is the frequency, the weaker are oscillations in the medium and the more is the sonar range, the lower is the thermal noise level. In this paper the optimal frequency for location in a water medium is found in a marine and river medium. As an optimal criterion for defining f_opt we took the ratio of intensity of echo signal to the sum of noise intensity and reverberation. We received a general ratio and formulas for typical instances