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Conditions for multiple acquisition of echoes from stationary targets in successive transmissions of active sonars

Kilian Lech, Schmidt Aleksander, Rudnicki Mariusz

Vibrations in Physical Systems

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2022

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Vol. 33, nr 3

art. no. 2022308

EN

In echolocation, the highest possible number of contacts with a detected target is clearly decisive on the possibilities of echo processing to optimise the estimation of distinctive characteristics of the observed target. In hydrolocation, the slow propagation of acoustic waves in water reduces the number of contacts of echosounders and sonars with detected targets. The article considers model conditions for acquiring multiple contacts with stationary targets detected by various sounding methods - with echosounders, classic active sonars and side looking sonars. Appropriate formulas explicitly linking the possible number of echo signals from the target in a specific geometry of the survey performed at the assumed speed are presented. These formulas are intuitively clear and not very complicated, but their value lies in the ability to instantly combine the vessel speed with the sounding effects, and may be a clear argument for imposing a low sounding speed, which make it difficult to steer the vessel.

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Numerical Model of Surface and Quasi-Spherical Sea Noise and Its Application to Analysis of DIFAR Systems

Rudnicki Mariusz, Salamon Roman, Marszal Jacek

Archives of Acoustics

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2021

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Vol. 46, No. 4

591--604

EN

Various types of passive sonar systems are used to detect submarines. These activities are complex and demanding. Therefore, computer simulations are most often used at the design stage of these systems. For this reason, it is also necessary to simulate the acoustic ambient noise of the sea. The article proposes a new numerical model of surface and quasi-spherical sea noise and presents its statistical parameters. The results of the application of the developed noise model to analyse the received signals of the DIFAR1 sonobuoy are also presented.

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Impact of Spatial Noise Correlation on Bearing Accuracy in DIFAR Systems

Rudnicki Mariusz, Marszal Jacek, Salamon Roman

Archives of Acoustics

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2020

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Vol. 45, No. 4

709--720

EN

DIFAR type underwater passive systems are one of the more commonly used tools for detecting submarines. At the design stage, which usually uses computer simulations, it is necessary to generate acoustic noise of the sea. It has been shown that correlating noise significantly reduces these errors compared to the assumption that noise is uncorrelated. In addition, bearing errors have been shown to be the same in systems with a commonly used antenna containing five hydrophones, as in a system without a central hydrophone, which may be useful in some DIFAR system design solutions.