Based on Chinese Beidou Satellite Navigation and Positioning System,
Beidou Vessel Network is compatible with GPS satellite navigation system and has lots of functions including all-dimensional and all-day communication contacts with fishing boats and mastering of accurate fishing boat location. Its scope of communication covers the whole state and other countries and regions nearby. It can also effectively make up the dead zones that cannot be monitored by overseas vessels, and effectively protect the life and property safety of numerous fishermen.
Besides, it also sets up an effective communication and information interaction means for different fishery competent departments and oversea fishing boats, with which the fishery competent departments can catch fish cross borders in sensitive waters through system alert and warning, and the fishermen can seek help in time if disturbed, making it convenient for promptly mastering the offshore conditions, and composing a dispute.
The following three items shall be constructed for the Project: Beidou shipborne terminal, Beidou vessel data center & relevant network platforms, and application system.
1. Beidou shipborne terminal
According to the Project’s background and demands, the shipborne terminal shall be designed according to different functional unit (i.e. display control unit, Beidou communication unit, and maritime affairs unit) modules, including positioning, Beidou short message communication, voice communication, management, alarming, display, electronic chart, etc.
2. Beidou vessel data center & relevant network platforms
It is necessary for Beidou Vessel Network to construct Beidou vessel data center, provincial monitoring & command center, first-class fishing ports at the municipal, district, county level, monitor terminals in townships, towns and villages, and relevant network links, so as to offer direct services to administrative departments at different levels, relevant government sectors, maritime search and rescue centers and other institutions.
3. Application system
Beidou Public Location Service Platform shall be utilized for relevant positioning service capabilities necessary for the application system of Beidou Vessel Network. The business functions shall be customized and developed based on specific demands. According to the investigation and analysis, application demands of the system include basic display of electronic chart, vessel data management, vessel supervision, accident investigation, vessel service, receive-disposal alarm function, remote terminal settings, system expansion, etc.
1. Terminal control frequency variation technology
As the vessel is moving, the satellite system will arrive at the ground through the ionized layer, and generate Doppler effect, causing certain deviation to the satellite frequency received by the terminal. In the base band algorithm, the clock frequency of radio frequency module is controlled by figuring out the frequency deviation between the local oscillator clock and the received satellite signal, and controlling AFC voltage through digit circuit, so as to maintain the clock frequency of the terminal consistent with the deviation to the received satellite frequency.
2. Open data exchange technology
Besides system operation, a complex system sharing one data interface with several business systems shall be capable of integrating with other business systems. The system provides a data exchange mode based on XML technology as well as the integration capability based on WEB embedded technology and the business system.