Frequency Hopping Signal Parameter Estimation And Modulation Recognition

Frequency Hopping Communication System (FHCS) has become more and more popular these years especially in the military field because of its outstanding anti-jamming capability. So the researches on jamming of FHCS are a key part of electronic warfare. Among many areas of research in jamming, the parameter estimation is extremely important. Because it directly affects the follow-up processes.In this dissertation, my main work is to estimate the parameters, recognize the modulation and study the synchronization signals of intercepted frequency-hopping (FH) signals. It includes the following several aspects.1) We described the basic principle of FHCS, the components of this system,the commonly used jamming methods and synchronization methods. At last, we also carried on the computer simulations.2) We made a profound research on three mainstream approaches of non-stationary random signal analysis, including Short-Time Fourier Transform (STFT), Wigner-Ville Distribution (WVD) and Wavelet Transform (WT), and fully understood their strengths and weaknesses. We also used these approaches to analyze frequency-hopping signals.3) After an in-depth analysis on STFT, WVD and WT, we proposed an algorithm based on Short-Time Fourier Transform & Least Square & Kay (STFT-LS-Kay) to balance the accuracy and efficiency. The simulation results indicated that this algorithm was a good real-time processing method for high speed frequency hopping signals.4) We carried on the modulation recognition of 2FSK, BPSK and QPSK signals on the conditions of slow speed frequency-hopping.5) We focused on the research of synchronization method of commonly-used frequency hopping radios and finally found an operational technique of jamming these radios by interfering with their synchronization signals. So when designing the synchronization signals of FH radios, this jamming technique should be considered in order to improve their counter interference capability.