Equalizer with perturbation effect based adaptation

Abstract

Equalization methods and equalizers employing discrete-time filters are provided with dynamic perturbation effect based adaptation. Tap coefficient values may be individually perturbed during the equalization process and the effects on residual ISI monitored to estimate gradient components or rows of a difference matrix. The gradient or difference matrix components may be assembled and filtered to obtain components suitable for calculating tap coefficient updates with reduced adaptation noise. The dynamic perturbation effect based updates may be interpolated with pre-calculated perturbation effect based updates to enable faster convergence with better accommodation of analog component performance changes attributable to variations in process, supply voltage, and temperature.

Description

Background technique [0001] Digital communications occur between a sending device and a receiving device through an intermediate communications medium or "channel" (eg, fiber optic cable or insulated copper wire). Each transmitting device typically transmits symbols at a fixed symbol rate, while each receiving device detects the (possibly corrupted) symbol sequence and attempts to reconstruct the transmitted data. A "symbol" is a state or salient condition of a channel that persists for a fixed period of time, referred to as a "symbol interval". For example, a symbol may be a voltage or current level, an optical power level, a phase value, or a specific frequency or wavelength. A change from one channel state to another is called a symbol transition. Each symbol may represent (ie, encode) one or more binary bits of data. Alternatively, data may be represented by symbol switching, or by a sequence of two or more symbols. [0002] Many digital communication links use only on...

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Problems solved by technology

[0002] Many digital communication links use only one bit per symbol; a binary "0" is represented by one symbol (e.g., a voltage or current signal in a first range), and a binary "1" is represented by another symbol (e.g., , a voltage or current signal in the second range), but higher order signal constellations are known and frequently used

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