Design Of Low Cost Weather Facsimile/NAVTEX Integrated Receiver

Weather facsimile receivers and NAVTEX receivers are indispensable and important equipment for ships and other offshore platforms.The former can enable the ship to grasp the local meteorological information in time in each sea area of the world.The latter is an important part of GMDSS,which enables the ship to receive the warning information in the nearby sea area.With the development of navy in Our country,the independent research and development of ship communication equipment has been paid more and more attention.At present,most of the more mature receiver products in China are single-machine single-use,that is,a receiver can only receive naivotex information or meteorological facsimile images independently.For the meteorological fax /NAVTEX all-in-one machine development,only a small number of domestic institutions are in progress,and the all-in-one machine development cost is high,compared with foreign equipment,the market competitiveness is obviously insufficient.According to the current domestic development of all-in-one machine,this paper designs a low-cost weather facsimile /NAVTEX integrated receiver.In this paper,according to the functions of each part of the all-in-one machine,it is divided into three parts: rf front-end module,baseband signal processing module and system main control module.The rf front-end module adopts the classical superheterodyne architecture,which mainly performs multiple filtering,mixing and amplification processing on the weak RF signals received by the antenna,so as to obtain baseband modulated signals conforming to ADC sampling conditions.Baseband signal processing module used the dual-core processor,CPU1 and CPU2 nuclei using asynchronous parallel way of receiving treatment,at the same time use the dual-core processor chip ADC sampling baseband modulation signal,and then software demodulation of FSK digital signal after sampling,CPU2 nuclear also has carried on the decoding to NAVTEX information,effectively simplifies the hardware circuit,reduce the manufacturing cost.The main control module of the system adopts the microprocessor with low cost,and introduces the embedded operating system to realize and manage the functions of data receiving,information storage,image format processing,man-machine interaction and so on.In this paper,according to the functional requirements of the all-in-one machine,in terms of hardware,the hardware circuit design of three modules is mainly completed.In software,mainly completed the dual-core processor and microprocessor software program design,microprocessor program using embedded operating system.Finally,the function of the whole machine is tested,and the results show that the basic functions of the low-cost meteorological facsimile /NAVTEX integrated receiver,such as meteorological facsimile image and NAVTEX information receiving,uploading and displaying,can operate normally.