The Research And Implementation For Adaptive Frequency Hopping System Based On FPGA

Adaptive frequency hopping (AFH) communication is more effective communication technology for combating interference than normal frequency hopping(FH). Real-time communication link quality assessment, adaptive power control and adaptive frequency selection technology are used in adaptive frequency hopping communication systems to ensure the correctness of transmission and enhance the reliability of communication.In this paper,an adaptive frequency hopping communication system is designed by FPGA technology which works in short-wave band.The system is designed for military wireless communications which demands anti-jamming,confidentiality and electronic countermeasures.Author has deeply learned and researched the basic principle and key technologies of adaptive frequency hopping communication,and short-wave radio channel anti-jamming technology.Completed the adaptive frequency hopping communication system's design, and given the overall structure of the system and set the relevant performance parameters.According to design proposal,the system adopt FPGA development tools,firstly constructed the conventional frequency hopping communication system which include the source module,channel coding module,the pseudo-code generator module,frequency hopping module,modulation and demodulation module,low pass filter module,etc.On this basis, importantly researched and designed the channel estimation module and the adaptive frequency-replacement module which could fulfill adaptive frequency hopping according to real-time communication link quality assessment.In order to study the anti-jamming performance of adaptive frequency hopping system,designed and built a short-wave interference channel module.In setting the noise,fading and interference environment's short-wave interference channel.The bit error rate and signal's energy are measured.And obtain the relation-channel quality assessment's result.According to the result,replace bad single-frequency,bad multiple-frequency or the entire frequency band.Thus,adaptive frequency hopping feature could be achieved.Analyse the results of simulation-testing for the conventional frequency hopping communication system and the adaptive freque- ncy hopping system which work at the spectrum of 2MHz-5MHz and 6MHz～9MHz.Simulation and test results show that the adaptive frequency hopping communication system could achieve the correct channel assessment, adaptive frequency selection and other functions,Significantly enhanced anti-jamming ability of FH systems, and improved communication quality.