Apparatus and method of generating reference level of viterbi decoder

A method of generating a reference level of a Viterbi decoder, the Viterbi decoder receiving an input signal and outputting an output signal according to the reference level, the method comprising:

• receiving the input signal and the output signal from the Viterbi decoder;
• detecting a first reference level of the Viterbi decoder using a first delayed input signal and the received output signal;
• detecting second reference levels using the output signal from the Viterbi decoder and a second delayed input signal and a third delayed input signal input one clock cycle after and before the first delayed input signal;
• respectively calculating a first square level error for the first reference level and second square level errors for the second reference levels;
• and
• selecting as the reference level for the Viterbi decoder according to a result of a comparison between the calculated first square level error and the second square level errors.

An apparatus for generating a reference level of a Viterbi decoder which converts an input signal to an output signal using the reference level, the apparatus comprising:

• a first reference level detection unit to detect a first reference level using a first input signal and the output signal of the Viterbi decoder, and to calculate a first error using the detected first reference level and the input signal of the Viterbi decoder;
• a second reference level detection unit to detect a second reference level other than the first reference level using a second input signal and the output signal, and to calculate a second error using the detected second reference level and the input signal of the Viterbi decoder, the second input signal being temporally different from the first input signal;
• and
• a control unit to select the first reference level to be the reference level used by the Viterbi decoder where the calculated second error is more than the calculated first error, and to select the second reference level to be the reference level used by the Viterbi decoder where the calculated second error is not more than the calculated first error.

A method of generating a reference level of a Viterbi decoder which converts an input signal to an output signal using the reference level, the method comprising:

• detecting a first reference level using a first input signal and the output signal of the Viterbi decoder;
• calculating a first error using the detected first reference level and the input signal of the Viterbi decoder;
• detecting a second reference level other than the first reference level using a second input signal and the output signal, the second input signal being temporally different from the first input signal;
• calculating a second error using the detected second reference level and the input signal of the Viterbi decoder;
• selecting the first reference level to be the reference level used by the Viterbi decoder where the calculated second error is more than the calculated first error;
• and
• selecting the second reference level to be the reference level used by the Viterbi decoder where the calculated second error is not more than the calculated first error.