Abstract: The present invention provides accurate, unbiased adaptive gain control in high speed digital communications systems. The probability of receiving each of a plurality of symbols to be transmitted over a data communications channel is determined for the predetermined communications protocol used over that data communications channel. Based on the probability determined for each symbol, an adaptive gain control adjustment factor is established for each symbol. During active communications, symbols transmitted over the data communications channel are detected, and the adaptive gain control value is selectively adjusted using an adjustment factor established for the detected symbol. Accordingly, adaptive gain control updating in accordance with one embodiment of the invention employs different step sizes for incrementing and decrementing the adaptive gain control value depending on the magnitude of the symbol received.

Abstract: A method and apparatus for recovering a timing phase and frequency of a sampling clock signal in a receiver are disclosed for determining a desired timing phase by minimizing a mean squared error due to uncancelled precursor intersymbol interference. A detected symbol error is correlated with a signal obtained from the received signal. This correlation function provides an approximate of the time instant where the mean squared error approaches its minimum at which point an unambiguous zero crossing of the correlation function signal is obtained. From such an unambiguous zero crossing, e.g., only one zero crossing, a desired sampling timing instant is determined.