As the introduction of the Global Maritime Distress and safety system(GMDSS), the marine wireless communication was changed from basis on the analogue communication method to basis on the digital communication method, such as Inmarsat, Navtex, Narrow band direct printing(NBDP), digital selective calling(DSC) etc.
Recently, the most high value-added new building ship has the computer network system, engine monitoring system, special cargo monitoring system etc. Above systems are implemented by the digital signal processing & digital communication technology.
The ship's inboard broadcasting & wire communication system is largely divided to public address system, telephone system and communal aerial system. And the telephone system is divided to the auto telephone system using the auto exchanger, common battery telephone system using the ship's emergency power source(DC24V) and sound power telephone system that no need the external power source input.
In case of the common battery telephone system, it is used as duplicated telephone system with the auto telephone system and the telephone normally installed in the important place for navigation such as wheel house, engine room, engine control room(ECR), steering gear room etc. The system is consisted of maximum 12 number of telephone and operated as the hot-line communication.
Now, the produced common battery telephone is used the analogue communication technology yet and when increased the telephone number composed system, the core of connection cable between the telephones is increased.
On this study, the calling transmitting & receiving method of the common battery telephone is implemented by the micro processor and power line communication(PLC). So, the needed connection cable core to interface between the telephones is only 3 cores and it is able to compose 12 number of telephone like as the analogue communication system.