Capabilities to use passive measurement systems to detect objects moving in a water region

Abstract

The increase in the use of sea water is the basis for the development of the existing security systems in given areas. Monitoring the navigational situation in a given water area is one of the most important tasks aimed at ensuring the necessary level of safety in maritime traffic. Marine surveillance systems at sea are used for this purpose. As an interesting approach related to the study of the movement of vessels, this paper proposes a method based on the measurement of physical field disturbances generated by objects moving in the sea water. These disturbances can be referred to the upper (air space) and lower (underwater) hemisphere. In the upper hemisphere the motion of the object generates disturbances of the thermal field while in the lower hemisphere disturbances of the acoustic, hydrodynamic, magnetic, electric and seismic fields are generated. Detection of the floating objects and determination of movement parameters is realized mainly by active systems. There are radiolocation systems in the upper hemisphere (radar systems) and echo ranging systems in the lower hemisphere (sonars and echosounders). Monitoring of the upper hemisphere of sea vessels traffic is conducted in a comprehensive manner. The lower hemisphere is in the most cases omitted. Therefore, it is recommended to develop underwater observation systems as a source of additional information about floating objects and thus complement the existing systems used in navigation. However, at present, despite the technological progress, there is a noticeable lack of the comprehensive solutions in the area of monitoring the vessels movement in the underwater space. Therefore, appropriate action should be taken to recognize this technology gap and increasing the safety of vessel traffic. The aim of the article was to present a fully passive, mobile underwater observation system that uses a number of sensors to monitor the underwater environment parameters, the research methodology and analysis of the obtained results. The method of deploying the measurement system at the selected geographical position and the measurement method are described. Based on obtained results, the analysis of sound pressure disturbances caused by passing ships was performed. A feature extraction method was developed to identify a passing vessel based on low frequency signal parameters.