ADCP Real-Time Ocean Current Information Displaying On Electronic Navigation Chart

Real-time ocean current information plays an important role in guaranteeing the safety of lives and property, and improving enter efficiency when ships enter the seaports. Combined with the Electronic Chart(ENC)and precise positioning information, the real-time ocean current information can provide navigators with a clear picture of the current status in the seaports, which can not only save navigators'time to calculate the current value from Current Table, but also help navigators to determine the time and the way of enterting the seaport by considering the magnitude and direction of the ocean current.This is a good way to guarantee the safety of the lives and property, and improvetransit efficiency.In this article, taking the real-time ocean current information displayed on the ENC as research objects, the author tries to investigate wire-less transmission scheme for real-time ocean current information which has been measured by the ADCP(Acoustic Doppler Current Profiler). After the original data measured by the ADCP has been parsed, the quality and veracity of the data has been controlled and garanteed. Timer is also added to the ECDIS to update real-time current information.In this article,the author has done the following things:(1)ADCP real-time ocean current information collection and decoding:Using WorkHorse Series Rio Grande ADCP of RDI company to measure the current, and transmit data that measured by far-away ADCP using wireless radio. Introducing ADCP coordinated system and parsing ADCP measurement data, the data which has been parsed contains latitude and longitude of the measurement site, each water layer current magnitude, direction, data correlation, the percent-good data and so on.(2) Quality Control and storage of ADCP real-time current information:By analyzing the system and random error of ADCP measurement data, combined with data correlation, the percent-good data, the change of current magnitude in the adjacent water layer and other information, a program of data quality control has been designed which based on data quality control theory:the original measurement data is marked and divided and then the data which meet the quality control has been inserted into SQL Server database.(3)Ocean current information which according with IHO S-52 production specification displaying on ECDIS:In accordance with the IHO S-52 production specification requirements for nongravity current, when draw the current symbol on ECDIS the current size should be converted from millimeter units to pixel units.And the current colour should also be converted from the Lab color model of the International Standards Committee on Illumination (CIE)to the RGB (red, green and blue) color model which has been usually used by computer graphoscope.Basing on the theory described above the ocean current symbol has been designed.The two-dimensional graphic rotation theory in computer graphics and the usage of the font type in MFC CFont class have been used to achieve the displaying of current direction and current magnitude.(4)The ECDIS installing on ships updating ocean current information automatically and regularly:Setting timer in the client ECDIS to make the client ECDIS to access the server that storage the ocean current data regularly, get ocean current information in the recent moment, and add the current information on ECDIS basing on ocean current symbol and using a new layer to achieve current data updated in real time.