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1
Content available Noise effect on parameters of quiet sonar with code modulation
Salamon Roman, Marszal Jacek, Jedel Andrzej
Vibrations in Physical Systems
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2023
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Vol. 34, nr 1
art. no. 2023109
EN
Earlier publications of the paper authors have shown that the use of code keying mixed with the CW FM sound signal allows the significant reduction in the distance measurement error, compared to classic silent CW FM sonar. In addition to the code modulation parameters, the magnitude of this error is influenced by the received input acoustic noise. The article shows the dependence of the input signal-to-noise ratio and the sound signal parameters on the target distance measurement error and the detection conditions, such as the output signal-to-noise ratio and the side lobe level. The results of the analysis were compared to the same parameters of the CW FM silent sonar without code modulation.
2
Content available 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.
3
Content available Underwater navigation system based on Doppler shift – measurements and error estimations
Ostrowski Zawisza, Salamon Roman, Kochańska Iwona, Marszal Jacek
Polish Maritime Research
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2020
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nr 1
180--187
EN
A new acoustic navigation system was developed to determine the position and speed of moving underwater objects such as divers and underwater vehicles. The path of an object and its speed were determined by the Doppler shifts of acoustic signals emitted by a transmitter placed on the object and received by four hydrophones installed at the periphery of the monitored body of water. The position and speed measurements were affected by errors mainly caused by acoustic reflections (returns) from the water body boundaries and surface reverberations. This paper discusses the source of the disturbances with the results of a simulation test and experimental measurements. It was demonstrated that the magnitude of the errors could be acceptable in most of the potential applications of the acoustic navigation system.
4
Content available 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.
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