| 摘要 |
A preceding system to achieve rates higher than 33.6 kbps in the analog modem to digital modem direction. The preceding system modifies the standard THP algorithm to adapt it for use in PCM modems. The present invention overcomes the above-described difficulties by preceding an upstream signal before transmission. In one aspect of the invention, the present invention provides a precoder for generating a mapped constellation signal from an input signal. In one embodiment, the precoder includes a processor configured to generate the mapped constellation signal from the input signal by mapping input signals in a plurality of distinct ranges onto a basic level. The processor is configured to map the plurality of distinct ranges onto the basic level following different arithmetic rules for at least two of the plurality of distinct ranges.
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