Methods and apparatuses for blind equalizers with multiple constant
modules. In one embodiment, a circuit, includes: a filter to produce an
output based on an input that represents a symbol being received, the
symbol being one of a Quadrature Amplitude Modulation (QAM)
constellation; a decision engine coupled to the filter to generate a
result indicating one region of a plurality of regions in a QAM
constellation diagram, the output of the filter being in the indicated
region which includes a plurality of symbols of different radii in the
constellation diagram; and an error reduction engine coupled to the
decision engine and the filter to reduce a difference between a selected
one of a plurality of constants and a modulus of the output; where each
of the plurality of constants correspond to one of the plurality of
regions; and the selected one of the plurality of constants is selected
according to the result of the decision engine.