Nonlinear Channel Transmission Code Identification Method

The purpose of this thesis is to recognize the codes in the signal via a nonlinear channel such as oil-pipe acoustic channel. In the first part of the thesis the properties of the oil-pipe acoustic channel and the signal in the receiver of the system are analyzed. Then, the idea of speech signal processing is introduced into the system. Afterwards, three kinds of endpoints detection algorithms and their performance are discussed. Finally, two algorithms and improved algorithms of signal enhancement are introduced. Their performance in noise canceling is also compared and their relations are analyzed in the dissertation. The conclusion is that improved algorithms have better performance in noise canceling, amplitude subtraction algorithm and power spectrum subtraction algorithm have the almost same performance, and they are effective for the white noise and color noise with Gauss distribution.