A novel Doppler shift estimation via optimum bandwidth filtering in HF/VHF communications

In HF/VHF communications, the received signal is easily overwhelmed by various noise and interference signals, which has seriously affected the estimated accuracy of Doppler frequency shift, the band-pass filter (BPF) is used to suppress noise and interference effectively. Nearly everyone agrees that the more noise suppression and the more accurate the estimated results. Nevertheless, in this paper, through theoretical analysis and simulation results for the classical methods such as level crossing rate (LCR), we educe a conclusion that there exists an optimum bandwidth ratio to minimize the estimated error of Doppler frequency shift, and appropriate bandwidth noise is helpful to improve estimation performance. Therefore, in order to ensure the accuracy estimation of Doppler frequency shift under low signal-noise-ratio (SNR) conditions (γ<;0dB), the optimum bandwidth ratio of BPF is deduced and determined, with which the estimation performance of proposed method is always superior than 2~5dB, comparing with current methods.