Researches On Reconnaissance And Frequency-Hopping OFDM Anti-Jamming Technique In Communication Counter-Measure System

Reconnaissance and Anti-jamming for communication is an important component of communication counter-Measures. The purpose of reconnaissance is to take a variety of measures to detect and identify the technical parameters, characteristics and locations of enemy's communication signals, the functions and components of enemy's communications network. The purpose of Anti-jamming is to eliminate or weaken the hazards of enemy's jam for communication, protect equipments and functioning of our communication systems.This dissertation researches the algorithm of carrier frequency measurement, signal bandwidth measurement and modulation scheme recognition by analyzing basic principle of reconnaissance for communication. Furthermore, the algorithm is implemented on Digital Signal Processor (DSP) using signal processing technology. Fast Fourier Transform (FFT) is applied to achieve multi-signal carrier frequency measurement and bandwidth measurement, and decision-theoretic approach is applied to achieve modulation scheme recognition. The test result demonstrates that the simulation algorithm achieved on MATLAB can be effectively transplanted to DSP.On Anti-jamming, this dissertation discusses the OFDM technologies and frequency-hopping communication technologies, and simulates the performance of OFDM signal and frequency-hopping signal respectively associated with widely used jamming techniques in communication counter-Measures, such as partial-band jamming, multitone jamming and so on. Firstly, the anti-jamming performances of OFDM under partial-band jamming and multitone jamming are analyzed. Then Subcarrier-Hopping OFDM is proposed. Moreover, the anti-jamming performances of Subcarrier-hopping OFDM in same jamming conditions are also analyzed. By comparison with OFDM, it demonstrates that the anti-jamming performance of Subcarrier-hopping OFDM is better than that of OFDM in both environments.