| Chinese fishery have the characteristics of high risk and high motality rate. These properties reflect that fishery communication is closely related to the life and property of many people. The present fishery ultra-short wave radio set have many faults, such as poor voice quality, long call setup time, single function and available spectrum is limited. At the post-PC age, with the development of computer technology and communication technology and internet application are used more and more widely,the embedded technique have become one of the most potential technologies in the future time,will develop quickly and can be widely used. Linux system is a multi-user, multi-task and multi-platform operating system which observes the POSIX standard and 32-bit (or 64-bit) open source. From it was invented, only a few years, Linux had grown into the second largest operating system.In this paper, firstly, in accordance to the《request of universal technical standard of VHF frequency radiotelephone that used by fishery marine》and cooperation company, aiming at the low drivers and remote calls the article put forward the overall scheme and implementation method .The scheme used embedded Linux technology to scheduling task,were easy to operate This paper mainly introduced the embedded system and the low drivers which communicatied with DSP using the double channel RAM, at the same time, this paper puts forward a implement method on the design of remote calling system. Due to the need, internet phone use half-duplex communication. This means when one party send message, it is unacceptable. When one party accept message, it's unable to send. Video recording and sending are treated differently by thread, broadcast and accept are treated differently by thread too. At the same time, double buffers is used for buffer data, fully independent task scheduling. There have no insiderable influence between them, implementing half-duplex network functions. |
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