The Design And Implementation Of Communication Module In Fast HF Frequency Selection And Link Establishment System

As an important communication technology of modern wireless communication, HF communication has the advantage of flexible usage and long distance transmission, which is widely used in daily life. Especially with the proposal of the 3G-HF communication standard, the research enthusiasm of HF system is greatly inspired. But HF communication is of its own disadvantage. Because of depending on ionosphere, HF system has realized its long distance transmission. However, the poor channel environment of the ionosphere has brought some difficulties to HF communication. So it's necessary to design an effective channel detection system.Firstly, a Fast HF Frequency Selection and Link Establishment System is given in this thesis, which can receive signal on 30 channels within a single dwelling time. This system can effectively shorten the time for frequency selection and link establishment. The signal processing module in the system is mainly studied based on the TMS320C6455+FPGA platform in this thesis. The hardware design of the system is discussed. The network interface module, the DDR2 module and UART module in hardware system are mainly discussed.Then, the Fast HF Frequency Selection and Link Establishment System is discussed,including the structure of the whole system and two important communication stage:Blind-Scan stage and fixed-frequency communication stage. The system flowchart is presented afterwards. Next, the software design and the implementation of the communication module are specially introduced, including configuration of the DSP/BIOS system used in the above platform, the way to use the NDK software, the design of the multi-thread programs, the method to boot the DSP/BIOS program, etc. Then, system designs is confirmed by test.Finally, based on the Fast HF Frequency Selection and Link Establishment System, a new broadband HF data transmission protocol is designed according to the old data transmission protocol used in laboratory. When there is no data to send, the blanks are transmitted to keep communication instead of EOM transmission, which can improve the real-time performance of the system. The new protocol also simplifies the data transmission which can reduce redundancy when exchanging data and improve the performance of the system. At last, the new protocol is test.