| 摘要 |
A method for detecting nonlinear distortion over communication channels. The method utilizes moment invariants in determining whether nonlinear distortion exists. The method is particularly applicable to detecting the presence of nonlinear distortion over telephone lines that are used for modem communications. The detection of the presence of nonlinear distortion is important in order that appropriate processing operations be performed which are required in the presence of such distortion. The particular processing operations that are performed in the presence of nonlinear distortion function to improve the reliability of data transfer especially at higher data rates. The nonlinearity distortion is detected by calculating high order moment invariants of the error magnitude present at the input to the slicer stage in the receiver. The method of the invention is effective, in part, because the probability density function of the noise is different, i.e., has a different shape, for a channel that contains nonlinear distortion than for one that contains linear, i.e., Gaussian, distortion. In addition, the moment invariant is more sensitive to the size of the error and not necessarily the energy level of the noise.
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