FH Signals Blind Parameter Estimation Algorithms Research

Frequency-hopping (FH) communication technology has been widely used in military communication field on account of its good anti-interference, low interception rate and other advantages. Nowadays, many military radio stations have made good use of FH technology. Military HF/HF and VHF/HF radios play an important role in communications, simultaneously which become a great challenge to communication countermeasure. In the field of communication countermeasure, deeply researching the FH communication to find a method of intercepting and identifying the FH signal becomes an urgent problem to be solved.The parameters estimation of communication signals is a part of Radio Communication Technology Detection, whose aim is to get technical parameters of enemy's communication facilities, such as communication systems' type, frequency, modulation, and so on. These parameters can be used to configure interfere equipments. Estimation parameters algorithms can be divided into single-antenna and arrays-antenna according to the type of antenna receiving equipment. In this dissertation, researches on these two areas are presented as follows:For single-antenna FH signal parameter estimation, algorithms in public papers are analyzed and summarized. Then different algorithms based on Time-Frequency analysis, which don't need to know the prior knowledge of the FH signals, are carried out in this dissertation. First of all, two kinds of classic algorithms based on Time-Frequency analysis concerning high-speed signals and low-speed signals are implemented. They have some disadvantages, such as relying much on the signal hop speed and bad assessment performance in the low SNR. To solve these problems in the algorithms, an improved parameters estimation algorithm based on speed forecast and time-frequency matrix processing is proposed. The simulation results show that when SNR is greater than or equal to -6dB, the parameters estimation performance has been greatly improved.For array-antennas signal parameters estimation, one classic method is simulated and analyzed. And the separation of mixed signals is completed. For constant frequency signal, the estimation of carrier frequency and identification of modulation type are completed; for FH signals, the separation of two kinds of FH signals and parameter estimation are also fulfilled. The results show that when the receiver array is the uniform circular array and SNR is greater than or equal to -5dB, the FH signals can be separated correctly. And using plane array to receive and SNR is greater than or equal to -3dB, the FH signals can be separated correctly. After the separation, the FH signal parameters are estimated. With error analysis, conclusions about algorithm performance with SNR and hop speed are found. This algorithm is more suitable for low speed signals.Finally, the prospect of the estimation parameters of FH signals and communication countermeasure technologies are presented. Some further developing way which might worth researching is given.