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Abstract

Severe error detectors, methods, and computer program products use constellation specific error event thresholds to detect severe error events in a signal comprising symbols from a plurality of symbol constellations. In particular, a plurality of constellation thresholds are defined that correspond to a plurality of symbol or signal constellations. An output signal sample, which is associated with one of the plurality of symbol constellations, is received from a decision feedback equalizer. The absolute value of the output signal sample is compared with the constellation threshold that corresponds to the particular symbol constellation associated with the output signal sample. If the absolute value of the output signal sample exceeds the constellation threshold, then a severe error is recognized. The ITU V.90 Recommendation allows up to six different symbol or signal constellations to be used in the same communication session. The multiple constellations may be designed such that an error threshold suitable for one constellation may not be suitable for another constellation. As a result, a severe error detection circuit or module using a single constellation threshold for detecting severe errors may either under report or over report severe error events. Advantageously, multiple constellation thresholds may allow severe errors to be detected with greater precision than could be detected using a single constellation threshold.

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