The Study of Transducer Attitude Bias of the Single Beam Echo Sounder related with Sounding Error
Date Issued
2014
Date
2014
Author(s)
Hsu, Ming-Yi
Abstract
For the bathymetry, using single beam echo sounder and multi-beam echo sounder is the most common approach. Its source of errors include positioning, vehicle’s attitude, acoustic speed variation, and some others. Recently, by reason of quite full coverage for bathymetric data and making it easier to achieve the accuracy requirements for topographic differences works, multi-beam echo sounder is the popular way in the nearshore areas. Nevertheless, at shallow depths less than several meters, reaching complete coverage needing denser survey lines, and the high risk of multi-beam’s transducers colliding with the ocean bottom due to high-priced of the transducers, which are the reason that surveyors are the lower willingness in using a multi-beam sounder in the nearshore areas. Consequently, to take into account the costs and businesses will, single beam echo sounder is still the mainstream for variation in the environment of the project. The main problem of bathymetry by using single beam echo sounder for representation of data is from the lack of resolution capabilities of topography. In addition to the larger sound beam width, the resolution will deteriorate with the survey area becoming deeper, and distribution of the sounding beams will not make data complete coverage. For the survey work in the nearshore areas, survey vessels often change, and the instrument will need to reinstall for each survey vessel. There are the expected measuring errors due to the fact that setting up from human factors. This study is to analyze that the installation of transducer without pointing form surface to the seabed vertically produce poor results. Besides, we will discuss how influence of accuracy affects when dynamic motion sensor and transducer are not put the same level. Therefore, these two factors will cause the bias of the angle of ship by the wave swing. Then, the output data of dynamic motion sensor is not corrected by the centrifugal, which caused the unpredictable sounding errors in the turning of the vessel or changing the survey line. In this study, we propose the solution to the above problems, and the method is to improving the differences in survey lines of the distribution of data. Thereby, it is improved the accuracy of the measured values by calculating the bias of angle between the transducer surface and horizontal plane.
Subjects
單音束測深
姿態參數
誤差
Type
thesis
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