Research On VoIP-based VHF Communication System In VTS

With the rapid development of maritime traffic, the traffic density increased dramatically, There's a growing need for improving the maritime traffic safety management. Therefore, the Vessel Traffic Services(VTS) system is widely introduced by the maritime authorities of the current main ports to ensure the navigation safety of the ships. As an integral part of the VTS system, VHF(Very High Frequency Radiotelephony) communication subsystem plays the main role in providing voice communication to ensure the normal and effective contact between the VTS and the vessels within its region. However, the shortcomings of the traditional VHF communication system, such as low bandwidth efficiency, high cost and lack of on-duty manpower in the remote stations seem to make it fall behind the development of the modern VTS System.This thesis, in order to meet the demands of modernization VTS and aiming at the insufficient of traditional VHF communication system, is based on the the VHF communication subsystem researching in the project of "the branch project of Zhicheng bridge station and Badong station of Yichang vessel traffic management system" for Yichang maritime authorities. This thesis focuses on the basic theory and the key technologies of VoIP, As the application of the theoretical basis mentioned above, an VHF communication system based on VoIP is designed. This system makes the personnel in the operating center can establish conversation with the ships by connecting to the transceivers in the remote base stations via the IP packet switch network, and the remote watching for personnel on-duty is achieved. Meanwhile, the system also makes the corresponding digital voice management solution to achieve the voice compression and storage. By the assistance of IP network, voice replay remotely becomes possible which can help provide conclusive evidences in maritime affairs and authority surveillance, and it fully meets the VHF voice communication system modernization management needs.The thesis introduces modern advanced VoIP technology to the VHF communication system, in order to solve the voice transmission problems existing in the current VHF communication system. As a result, the important shift-from the unattended station to the personnel on-duty watch remotely is carried out, which can greatly expand the communication range of the VHF communication system and save the operating cost. Meanwhile, the voice communication system realized in the thesis can also serve as reference for other occasions needed, so it has high practical value.