1. A signal detector for detecting channel data in an input signal, the signal detector comprising: preprocessor circuitry responsive to the input signal and an output of a nonlinear detector to adapt at least one parameter used by the nonlinear detector to calculate a branch metric; and loading circuitry to normalize the at least one parameter by computing a term comprising a function of the at least one parameter and other parameters and an offset term, wherein the function includes a comparison operation of the at least one parameter and the other parameters.