US Patent 7245675 Upstream data transmission

A process transmits digital data to an A/D converter via an analog channel. The process includes generating a sequence of output signals by preceding a sequence of input signal points to precompensate for ISI in the analog channel. In the preceding is matched to the ISI, at least one of the output signals would be distorted by the ISI to a signal representative of a signal point lying between quantization levels of the A/D converter. If the precoding is matched to the ISI, others of the output signals would be distorted by the ISI to signals representative of signal points that are quantization levels of the A/D converter. A majority of the input signal points are quantization levels of the A/D converter.