非合作短波通信接收机关键技术研究.pdfVIP

Abstract Abstract No matter in civilian communication or military communication, non-cooperative communication receiver has very great application value. Due to the channel uncertainty and receiver unpredictability of non-cooperative communication, higher performance of receiver technologies is required in practical application. Especially in High frequency (HF) communication, the channel environment is very poor, the received signal is seriously distorted, which makes the research of the key technologies of non-cooperative HF receiver is a challenge. Supposed the modulation mode recognition and symbol rate estimation had been done, this article studies the key technologies of non-cooperative HF communication receiver, including the carrier restoration, symbol synchronization, and blind equalization. The main jobs and innovations of this paper are as follow: (1) The carrier frequency offset estimation and phase estimation algorithms of the carrier restoration technology are studied. Most of the existing researches of blind frequency offset estimation are in the precondition that symbol synchronization had been done. However, this paper study the frequency offset estimation algorithms of HF communication before finishing the symbol synchronization, including MM algorithm and FFT based algorithm. The simulation results show that in non-synchronous symbol environment, MM algorithm has poor performance. The FFT based algorithm has good performance, but its performance is not so good when the signal noise tolerance becomes small. For the phase estimation algorithm, this paper mainly discusses the classic algorithms: VV algorithm and proposes an improved algorithm. Then,