Key Technologies Research And Implementation Of FSK High-speed Frequency Hopping Link

The frequency hopping technology is commonly used in spread spectrum communication systems. It is a kind of information transmission technology which has a time-varying carrier. Because of its good performance of anti-fading and anti-jamming, FH(frequency hopping) communication is firstly applied and developed in military communications and many military powers are attracted to invest a lot of money and manpower to research it. With the development of military FH communication, FH communication begins to enter the field of commercial communicaitons, such as: Home RF, GSM and Bluetooth.As an important indicator of FH, a stronger ability will be achieved on anti-jamming and anti-interception with a higher hopping rate. So the development of high speed and ultra wide bandwidth FH systems has obvious significance for our military and civilian communications. In this paper, we research on a FH system whose hopping rate is up to thirty-five thousands per second, after which design and implementation of the system are both completed according to requirements, and tests of the function and performance of the system are done on the experimental platform.Firstly, the solutions of key technologies are given:(1) The hopping sequence is generated based on the TOD and cipher key. Theperiodicity, the uniformity, the interval size and the Hamming correlationcharacteristics of sequence are analyzed;(2) Schemes of frequency hopping synchronization are achieved. Synchronizationsolutions include hopping capture, hopping tracking and synchronizationcontrol protocols. Hopping capture is based on the TOD. Hopping tracking isbased on correlation of PN code. Synchronization control protocols control thetransfer of synchronization states;(3) The frame structure and the baseband signal processing algorithm areproposed. According to the frame structure and baseband signal processingalgorithm, a simulation of FH link is completed. The simulation performanceis consistent with the theoretical performance;Secondly, the detailed designs of the link on the FPGA are presented. We divide the link into different modules according to different functions. From input-output interfaces definition to processing procedures, every module is analyzed and implemented on FPGA;Thirdly, the function and performance of the FH link are measured on the experimental platform. The results indicate that the FH link can transfer files correctly, and can resist 8 k Hz frequency offset; also its performance is only worse than simulation’s by 2 d B in AWGN channel. When Eb/N0 equals to 14.3 d B, the bit error rate is 7.99×10-7.The fast FH link discussed in this paper enriches the research of ultra-fast, ultra-wideband FH communications and can meet the needs of FH radio in a certain extent. It can be a reference for further study of ultra-fast FH communications.