MOORING TESTS OF THE SHIPThe measurements were carried out in Gdańsk Bay waters in the area free from disturbances generated by marine industry, merchant and naval ports and fairways. Schematic diagram of the testing range is presented in Fig. 1.

In this work we were interested in the use for the localization of the ship noise sources in the water environment. Particular interest was dedicated to identifying of narrow band contribution to the total spectra of the ship hydroacoustic noise. The analyses were performed in time and frequency domain. The diesel engine, the electric motor and the propeller have notably been studied and the different frequencies connected to these devices have been listed. Extensive measurements were made of the underwater radiated noise of K1 and K2, small vessels powered by an electric and diesel engines. The discrete Fourier transform and the short time Fourier transform and sound intensity method were used for a precise analysis. The coherence function was also performed to associate each component of underwater noise with the vibrating part of the engine, which generates it. The measurement results obtained here have been later analyzed and a criticism of each method has been done, focusing on its advantages in the field of the identification of the noise sources.

No abstract

ABSTRACT

It is possible to track a source of noise by determining the intensity of sound that informs about the sound energy ow direction. One of the methods of determining the sound intensity of acoustic signals is the so-called gradient method in which the pressure is measured with the use of two hydrophones placed close to each other. Tetrahedral antenna consists of four hydrophones spaced at regular tetrahedron vertices so that distances between hydrophones are the same. The tetrahedral antenna determines six virtual points in the middle of each edge and allows using sound intensity calculation algorithm to determine the noise source bearing. In our experiment, the antenna was located 23 meters below the sea surface and a source of noise was moving over it. The object that was moving along a straight line with a specic course was equipped with a GPS receiver. This allowed comparison of the obtained targeting results with the real track of moving object. The paper presents the object tracking algorithm which was implemented in the MATLAB environment as well as some of the results of research carried out on passive source noise tracking.