Information recording and reproducing apparatus and method and signal decoding circuit having improved noise processing characteristics

An information recording and reproducing apparatus comprising:

• an equalizer having an equalization target in which noises obtained after an equalization become close to white noises by training;
• a noise correlation arithmetic operating unit which calculates a deviation of noises for a present time point which depend on input signal patterns of the present time point and input signal pattern of the past or future in response to an input signal from said equalizer;
• a storing unit which stores said deviation of said noises;
• and
• an input signal arithmetic operating unit which calculates an input signal of a decoder from said deviation stored in said storing unit,
• the input signal pattern of the present time point referencing an input signal being processed at present, the input signal pattern of the past denoting a first input signal series of a first predetermined number of bits which is time-precedent to the present time point, the input signal pattern of the future denoting a second input signal series of a second predetermined number of bits which is time-subsequent to the present time point.

An information recording and reproducing method comprising the steps of:

• obtaining a deviation of noises and a correlation of the noises for a present time point which depend on input signal patterns of the present time point and input signal patterns of the past or future by training and storing them;
• obtaining white noise values for said input signal patterns in which colored noises are converted into white noises by using said correlation and deviation of the noises;
• and
• calculating an input signal of a decoding process from said white noise values and a deviation of the white noises.

An information recording and reproducing method comprising the steps of:

• calculating a deviation of noises at a present time point which depend on input signal patterns of the present time point and input signal patterns of the past or future by training, with respect to an equalized signal in which noises obtained after an equalization become close to white noises as a target and storing said deviation;
• and
• calculating an input signal of a decoding process from said stored deviation,
• the input signal pattern of the present time point referencing an input signal being processed at present, the input signal pattern of the past denoting a first input signal series of a first predetermined number of bits which is time-precedent to the present time point, the input signal pattern of the future denoting a second input signal series of a second predetermined number of bits which is time-subsequent to the present time point.

A signal decoding circuit comprising:

• a noise correlation arithmetic operating unit which calculates a deviation of noises and a correlation of the noises for a present state which depend on input signal patterns of the present state, and past or future states by training;
• a storing unit which stores said correlation and deviation of said noises;
• a white noise arithmetic operating unit which obtains white noise values for said input signal patterns in which colored noises are converted into white noises by using said correlation and deviation of the noises which were stored in said storing unit;
• and
• an input signal arithmetic operating unit which calculates an input signal of a decoder from said white noise values and a deviation of the white noises,
• the present state referencing an input signal being processed at present, the past state denoting a first input signal series which is time-precedent to the present state input signal pattern, the future state denoting a second input signal series which is time-subsequent to the present state input signal pattern.

A signal decoding circuit comprising:

• an equalizer having an equalization target in which noises obtained after an equalization become close to white noises by training;
• a noise correlation arithmetic operating unit which calculates a deviation of noises for a present time point which depend on input signal patterns of the present time point and past or future in response to an input signal from said equalizer;
• a storing unit which stores said deviation of said noises;
• and
• an input signal arithmetic operating unit which calculates an input signal of a decoder from said deviation stored in said storing unit,
• the input signal pattern of the present time point referencing an input signal being processed at present, the input signal paffern of the past denoting a first input signal series of a first predetermined number of bits which is time-precedent to the present time point, the input signal pattern of the future denoting a second input signal series of a second predetermined number of bits which is time-subsequent to the present time point.