Study Of DSC Communication Protocols And Implementation On DSP Application Board

DSC (Digital Selective Calling) is a terminal for distress alert in GMDSS's ground communication and also has digital selective calling functions. It is also an important method to establish communication link between radio equipments in GMDSS ground system and is more effective for radio communication.Most DSC shipborn equipments are made abroad, although few domestic companies are developing or producing DSC equipments, their products either have not reached practical level or do not meet all DSC technology requirements. As to the application of DSC technology in maritime mobile services, ITU gave two corresponding recommendations: ITU-R M.493-11 (technique characteristic) and ITU-R M.541.9 (operation characteristics).Previous research carried out in the Signal and Image Processing Institute of DMU used personal computers as the simulating DSC terminal, and realized the ITU recommendation ITU-R M.493-11 and recommendation ITU-R M.541.9. For the sake of developing practical DSP terminals, this thesis introduces the development of DSC terminal based on TMS320C5416 DSP.In this thesis, DSC coding method and the application of error-detecting and error-correcting method briefly are introduced first. Then the sequence format and calling sequences for different calling functions stated in recommendation ITU-R M.493-11 and different calling processing functions discribed in ITU-R M.541.9 are discussed and analysed. Basing on DSP developing environment CCS and SEED-MMI5402 DSP application board, a DSC terminal is developed with user interface according to the user menu of STR—6000A(Marine DSC/VHF Radio Telephone). The programs are developed with C and assembly language mixing programming, which realize calling sequence writing, calling sequence coding and transmitting, message receiving and decoding, analyzing and displaying functions, etc. The thesis implemented communication simulation using the port McBSP1 on SEED-MMI5402 DSP. Two simulating tests are also conducted. The first test is made by one single SEED-MMI5402 DSP, the single simulating DSC terminal transmits calling sequences and it can receive the call sequences. It can implement call relay, acknowledgement and other calling functions. The second test is carried out between two simulating DSC terminals. Each simulating DSC terminal can both send data to and receive data from the other terminal, implementing distress call, urgency call and safety call functions.