Narrow band partial response signal processing apparatus, signal processing method and information storage apparatus

A signal processing method of carrying out a signal processing for a partial response system, comprising:

• a code processing step of carrying out a (1−D) waveform processing for an input code;
• and
• an equalizing step of Nyquist equalizing the code string obtained by the waveform processing of the code processing section by setting ¼ of a maximum frequency determined by the code to be a Nyquist frequency.

An information storage apparatus for carrying out a signal processing for a partial response system through a recording medium, comprising:

• a recording means for converting an RZ input code into an NRZI code and recording the NRZI code in the recording medium through a write head, thereby giving a (1−D) waveform processing to the RZ input code;
• and
• an equalizing means for Nyquist equalizing a reproduction code reproduced from the recording medium through a read head based on an equalizing transmission characteristic obtained by dividing a cosine roll-off characteristic setting ¼ of a maximum frequency determined by the RZ input code to be a Nyquist frequency by a transmission characteristic of a magnetic recording and reproducing system.