Data recording method recorder and data reproducing method and device

A recording apparatus comprising:

• a head unit for scanning a recording medium having pre-recorded thereon data obtained on modulating M-bit data into N-bit data, where M<N, as a pattern of crests and recesses composed of bit parts and land parts between said bit parts;
• a controller for controlling whether or not discrimination data is to be recorded based on data read out from said head unit;
• and
• a signal processing unit for processing said discrimination data for recording, and for supplying output data to said head unit;
• said head unit recording said discrimination data so that said certain bit or bits of said N-bit data are changed, with the remaining bits of said N-bit data being fixed.

A method for reproducing data modulated from M bit data to N bit data, where M<N, from a recording medium having said data pre-recorded thereon, said recording medium also having further data recorded thereon so that a certain bit or bits of said N-bit data are changed, with the remaining portion of the bits of the N-bit data being fixed, said method comprising:

• reading out the data from said recording medium;
• extracting the remaining portion of the bits of the N-bit data of the read-out data;
• determining whether or not the remaining portion of the bits of the N-bit data extracted is of a fixed value;
• and
• giving a decision that there is no error if the extracted remaining portion of the N-bit data is of a fixed value.

A method for reproducing data modulated from M bit data to N bit data, where M<N, from a recording medium having said data pre-recorded thereon, said recording medium also having further data recorded thereon so that a certain bit or bits of said N-bit data are changed, with the remaining portion of the bits of the N-bit data being fixed, said method comprising:

• reading out the data from said recording medium;
• extracting the remaining portion of the bits of the N-bit data of said read-out data;
• determining whether or not the remaining portion of the bits of the N-bit data extracted is determined to be of a fixed value;
• and
• reproducing said further recorded data if the extracted remaining portion of the N-bit data is of said fixed value.

A method for reproducing data modulated from M bit data to N bit data, where M<N, from a recording medium having said data pre-recorded thereon, said recording medium also having further data recorded thereon so that a certain bit or bits of said N-bit data are changed, with the remaining portion of the bits of the N-bit data being fixed, said method comprising:

• reading out the data from said recording medium;
• detecting whether or not said certain bit or bits of the N-bit data read out is of a fixed value;
• and
• reproducing the further recorded data if said certain bit or bits is not of said fixed value.

A reproducing apparatus comprising:

• a head unit for reading out data modulated from M bit data to N bit data, where M<N, from a recording medium having said data pre-recorded thereon, said recording medium also having further data recorded thereon so that a certain bit or bits of said N-bit data are changed, with the remaining portion of the bits of the N-bit data being fixed;
• a demodulating unit for demodulating the data read out by said head unit;
• and
• a controller for extracting the remaining portion of the bits of the N-bit data read out by said head unit, verifying whether or not the remaining portion of the bits of the N-bit data extracted is of a fixed value, and for supplying said further recorded data to said demodulating unit if the extracted remaining portion of the bits of the N-bit data is verified to be of said fixed value.