Nobuyoshi Kouguchi

Experimental results of combined method of conventional and coherent Doppler sonar

Conventional (usually used) Doppler sonar, though unlimited by velocity range ambiguity, takes seconds to return valuable velocity readings. Coherent Doppler sonar has been proposed to provide accurate velocity with short time lag for current or turbulent. However the velocity ambiguity seriously limits its general application. In this paper, combined Doppler sonar is proposed to overcome the disadvantages of both conventional and coherent Doppler sonars. An adaptive algorithm is used for combined Doppler sonar to provide accurate and precise velocity information at a wide range of SNRs. Experiments are carried out to evaluate the performance of combined Doppler sonar proposed. Based on experimental results, with suitable ambiguity velocities, combined Doppler sonar can provide accurate and precise velocity information at a wide range of SNRs.

Experimental Results of Ship-To-Ship Lightering Operations Applied Velocity Information GPS

A ship-to-ship (STS) lightering operation takes place in order to transfer cargo (e.g. crude oil or petroleum products) between an ocean-going ship...

Navigator's decision-making and action model - synthetically subjective risk of collision

The aim of this study is to generate a standard ships navigators decision-making and action model that might become one index for safety navigation and navigational education area. It is important for a navigator to avoid targets and secure a navigation space for the prevention of collision. In this study, a navigator decision-making and action for avoidance is focused and navigators decision-making and action model is illustrated. And synthetically subjective risk of collision which is possible to be a new index of evaluation for avoidance is proposed and the example of application is shown.

Wave remote sensing system by GPS

It is well known that an observation of the long period gravity wave is very difficult to observe for its long period and small amplitude. In our recent research, an integrated wave remote sensing system utilizing multi-path GPS signals reflected from sea surface is proposed to measure accurate wavelength for long period gravity wave. The system is equipped with an arrayed GPS antenna that has a narrow fan beam directional pattern. It has a better performance to measure accurate wavelength than wide beam antenna in numerical simulation and it can acquire multi-path GPS signal reflected from specified sea surface in seaside experiments. In digital GPS signal processing, software GPS receiver is applied to estimate the relative time delays between multi-path GPS signals. In this paper, simulation results and seaside experiment results obtained by the wave remote sensing system are also presented.