Automatic Switching Technique for Speech Enhancement in HF Communications

HF communication is widely used in radio broadcast, military, emergency relief and many other applications due to its flexibility, mobility, low cost of equipment, and low dependence on infrastructure. Meanwhile, it has a severe shortage that its communication channel is very unstable, which brings much noise into the transmitted speech. In this paper, an automatic switching system is proposed to enhance the shortwave speech signals, which includes an objective quality evaluation algorithm for low SNR speech, a multi-channel speech alignment algorithm, and multi-channel automatic switching strategies. This system does not only apply to the multi-channel switching of shortwave channel speeches, but can also contribute to that of other low SNR speeches. In order to verify the effectiveness of the system, we conduct two sets of experiments. The experiment results show that the proposed system can effectively enhance shortwave speech signals as expected.