Channel Estimation And The Lfm Interference Detection, Short-wave High-speed Frequency Hopping System

The mature Shortwave Frequency-Hopping System is widely used in the martial anti-jamming communication because in the shortwave channel, the signals can be transmitted within a long distance and the transmitter-receiver is small. The Frequency-Hopping System performs well in anti-capturing and anti-jamming.The shortwave channel plays an important role for the reliability and quality of the communication. The research on the channel is very useful to improve the performance of the communication system. There are two types of factors we need to study-the natural part and man-made part. The former is mainly affected by the transmitting path. The characteristics of the shortwave channel such as multipath, fading and Doppler frequency shifting need to be estimated. The estimation of the fading is mainly studied in this paper. Meanwhile, there may be various man-made jamming signals between the transmitter and receiver. Linear Frequency-Modulated signal is one of them. It is important to detect the jamming signal for us to restrain it. This paper has done some research on the detection of LFM jamming.This paper mainly does some research on the channel estination and LFM jamming detection in Shortwave FFH(Fast Frequency-Hopping) System. Several methods are compared.Chapter 1 briefly introduces the characteristics of the shortwave channel, the theories of the Shortwave FFH System, and something about channel estimation and LFM detection;Chapter 2 introduces the basic theories and arithmetics of channel estination especially the pilot-based channel estimation. Considering the characteristics in Shortwave FFH system, we make use of the correlation in the time domain to do the channel estimation;Chapter 3 mainly researched the channel estimation in shortwave FFH system, including LS, feedback LS and feedback LMMSE . The simulation results are discussed. And the advantages and disadvantages of each algorithm are compared here. Chapter 4 introduces the LFM jamming signal and gives its mathematical model. The time-frequency characteristics are described and its effect on the shortwave FFH system is analized;Chapter 5 introduces several methods of LFM jamming detection in shortwave FFH system, such as Radon-Wigner Transform, Radon-Ambiguity Transform and FrFT Transform, including the detection of sigal-component and multi-componet. The simulation results are discussed;Chapter 6 is the summing-up of this dissertation and proposed the following research direction.