The Automatic Receiver Of Safe Information On The Sea

NAVTEX is an international automated direct-printing service for issue of navigational and meteor on logical warnings and urgent information to ship. It will fulfill an integral role in the GMDSS (Global Maritime Distress and Safety System) developed by the International Maritime Organization and is already contributing to safety on the sea.Software Radio is a new architecture of communication system that is brought forward these years in radio area. It breaks through the localization of traditional radio in simple function and bad expansibility, and it focuses on the new design idea which is based on open and common board and use updateable and reconfigurable internet applications to realize all kinds of radio function.In this paper, the Chinese NAVTEX receiver based on Software Radio are studied and implemented. Based on the performance requirement of the system, an analog-to-digital conversion circuit is adopted to sample the NAVTEX signal directly according as band-pass sampling theorem and the samples are processed in DSP. Through a digital band-pass filter, the signal in low frequency is obtained and taken out. The whole process of demodulation and decoding is completed after the samples are timed and detected. A novel algorithm to detect the 2FSK (Frequency-Shift Keying) signal is adopted to make the signal receiving simple, that is the Fast Fourier Transform algorithm. The study in this paper is adapted to the development and change of current maritime communication technology and provides some theoretic foundation for more develop of Chinese NAVTEX receiver by using the Soft Radio technology. It is provided with definite practicality. The significance of the paper is that it adopts the advanced digital technology and digital circuit design to meet the needs about high integration and steady performance of the system. That is to accomplish the system performance with the hardware as more simple as possible.