The Simulation Of Chinese NAVTEX System

NAVTEX is the system that broadcasts and automatically receives the maritime safety information by means of a Narrow Band Direct Printing telex (NBDP), which is the important part of the Global Maritime Distress and Safety System (GMDSS), too. The system uses the single frequency of 518 kHz to broadcast maritime safety messages in the English. If it is necessary, it may also use the frequency of 490 kHz to do in the local language.The paper introduces the concept, characteristic and service of NAVTEX system in detail. The simulation of system is did by means of the MATLAB software, and the result is same as the theory.Moreover, the paper discourses upon the basic theory, system structure of Chinese NAVTEX system, coding and encoding method. Then the simulating design gives a correct result. Every Chinese character is expressed by 3-English alphabet, so the transmission efficiency is improved by 40%. At the same external noise condition, the Horizontal-Vertical parity check code mode decreases two to three orders of magnitudes than the present ones.The results come up with significant improvement of diversity using Chinese Character Code of NAVTEX system, in terms of irreducible bit error, by using same diversity design. This paper also investigates the performance of ASCII code from these simulations.