Design And Implementation Of Fast Frequency Hopping System Module Based On FPGA

Because of the strong ability of anti-jamming, anti-fading, as well as confidentiality and other advantages, fast frequency hopping(FFH) communication system has been widely used both in military areas and civilian areas, result in broad prospects for development. This paper makes a deep research on the key technologies of the FFH systems, designing and implementing each module based on FPGA, which has high practical value.At first the development history, research situations and future trends of FFH system were introduced, followed by the theoretical basis and key technologies, including the frequency synthesizer, hopping sequence and synchronization. This makes a strong foundation for the following research.Secondly the main technical difficulties of FFH system were analyzed, namely high precision frequency synthesizer and fast synchronization technology, which can determine the quality of the entire system performance. A dedicated DDS chip was used as frequency synthesizer, configured by serial programming. After comparing three different acquisition methods and two tracking methods by simulation in performance and implementation complexity, the fast-out acquisition technology and early-late gate energy comparison tracking technology were considered to use in hopping synchronization module. Then the FSK modulation and demodulation techniques, diversity combining techniques and bit synchronization techniques were researched.At last the scheme and parameters were designed. Each module in transmitter and receiver was achieved base on FPGA and ISE software platform using Verilog language, especially including hopping acquisition, hopping tracking, 2FSK modulating and demodulating, bit synchronization esc. With the help of chipscope, oscilloscope and spectrum analyzer to verify the correctness of each module, a 2FSK/FFH communication system was complemented in the end.