# US 6,341,360 B1 · Decision feedback equalizers, methods, and computer program products for detecting severe error events and preserving equalizer filter characteristics in response thereto

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- Number: US 6,341,360 B1
- Document ID: US6341360B1
- Status: Granted
- Kind: B1
- Application number: 09/264,094
- Filed: 1999-03-08
- Granted: 2002-01-22
- Earliest claimed: 1999-03-08
- Web page: https://patentgrep.com/patent/US6341360B1

## CPC

- H04L 25/4927: {using levels matched to the quantisation levels of the channel}
- H04L 25/03057: {with a recursive structure (H04L25/03031 takes precedence)}
- H04L 2025/03363: {Multilevel (H04L2025/03369 takes precedence)}
- H04L 2025/03694: {Stop and go}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Decision feedback equalizers having a stabilization capability, and methods and computer program products for stabilizing a decision feedback equalizer under severe error conditions use output samples from an equalizer to determine whether a severe error event has occurred in accordance with predefined criteria. If a severe error occurs, then a determination is made to evaluate whether the number of severe errors that have occurred has exceeded a threshold. If the threshold has been exceeded, then the coefficients for the filter(s) in the decision feedback equalizer are preserved in their current state. Severe errors can cause the equalizer filter coefficients to be pulled away from their normal operating values, which can result in several modulation cycles passing before the coefficients are restored. By preserving the equalizer filter coefficients under severe error conditions, the present invention prevents sharp or dramatic changes to the coefficient values from their steady state values allowing the decision feedback equalizer to recover more quickly from the errors.