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US 5,633,632 AGranted
Data conversion method and apparatus imbedding pilot signal into converted data and reducing error propagation between datawords
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsKihei Ido, Masako Yamada, Hideaki Kosaka, Masayuki Ohta
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Abstract
A data conversion method, wherein a sequence of first r-bit datawords is divided into groups of x bits where x is the least common multiple of r and m, an arbitrary first dataword selected from x/r groups of first datawords is divided into x/m, an m-bit second dataword is formed by appending r/(x/m)-bit data, obtained by dividing the first dataword into x/m, to the LSB or MSB side of one or other of the non-divided first datawords, and the word-converted m-bit second dataword is converted to an n-bit codeword (m<n).
Claims53
A data conversion method for word-converting an r-bit first dataword to an m-bit second dataword (r<m) and converting the word-converted m-bit second dataword to an n-bit codeword (m<n) comprising the steps of:
- dividing a sequence of first datawords into groups of x bits and x/r first datawords where x is the least common multiple of r and m;
- dividing an arbitrary first dataword of each said group into r/(x/m) bit first dataword portions;
- and
- forming the m-bit second dataword by appending an r/(x/m)-bit first dataword portion to each remaining one of said x/r first datawords in each said group.
1 more element
An apparatus for converting r-bit first datawords into m-bit second datawords where r is less than m and into n-bit codewords comprising the steps of:
- dividing means for dividing each m-bit dataword into m1-bit and m2-bit dataword portions where a m1-bit dataword portion corresponds to a first dataword and where a m2-bit dataword portion corresponds to at least a portion of another first dataword;
- and
- assigning means for assigning to each m-bit dataword having m1-bit and m2-bit dataword portions first and second n-bit codewords each having n1-bit and n2-bit dataword portions corresponding to said m1-bit and m2-bit codeword portions, respectively, said first and second n-bit codewords having different CDSs (codeword digital sums) and forming n-bit codeword pairs, the possible number of codeword pairs which adhere to any run length limitation being sufficient to specify all possible said datawords, codes of at least one of said n1-bit and n2-bit codeword portions which adhere to any run length limitation being insufficient to uniquely encode said m1-bit and m2-bit dataword portions, respectively, and said assigning means assigning to each n1-bit codeword portion having a CDS of u, a pair of n2-bit codeword portions having CDSs of v and x respectively, such that u+v and u+x are said different CDSs, and wherein
- said assigning means first assigns n1-bit codeword portions and n2-bit codeword portions to said m1-dataword portions and said m2-bit dataword portions in unique one to one mappings, where possible, thereby minimizing error propagation between said n1-bit and n2-bit codeword portions, and
- where said unique one to one mappings to n1-bit and n2-bit codeword portions are not possible, said assigning means subsequently assigns unique combinations of n1-bit and n2-bit codeword portions to the m1-bit and m2-bit dataword combinations so that said n1-bit codeword portion must be known to decode the 2-bit codeword portion, or vice versa.
2 more elements
A magnetic recording/reproducing apparatus for recording multiple kinds of data formed by dividing digital data into 12-bit datawords and then converting the 12-bit datawords into 14-bit codewords having a most significant bit (MSB) side and a least significant bit (the) side said data being stored in partitioned areas, comprising:
- first means for converting digital data to codewords for recording on one or more areas within one track, the first means limiting the number of successive 0s between a 1 and another 1 in each said codeword to 4 or less within the codeword and to 2 or less at the MSB side of the codeword and to 1 or less at the LSB side of the codeword, codewords having a codeword digital sum (CDS) of 0 solely corresponding to each 12-bit dataword while for codewords having a CDS of +2 or -2, pairing the two codewords that differ only in MSB and which correspond to the 12-bit data, the two codewords being switched selectively by using polarity signals of the respective codewords;
- and
- second means for converting digital data to codewords in the other areas in the same track, the second means limiting the number of successive 0s between a 1 and another 1 in each said codeword to 4 or less within the codeword and to 2 or less at the MSB side of the codeword and to 1 or less at the LSB side of the codeword, codewords having a codeword digital sum (CDS) of 0 solely corresponding to each 12-bit dataword, while for codewords having a CDS of +2 or -2, pairing the two codewords that differ only in MSB and which correspond to the 12-bit data, the two codewords being switched selectively by using polarity signals of the respective codewords, said second means appending at least one bit to each 14-bit codeword to form a pair of codewords one having a CDS of +1 and the other having a CDS of -1, with the number of successive 0s between a 1 and another 1 in the code sequence being limited to 4 or less, and one or the other of the pair of codewords being selected in accordance with the DSV control signal so as to produce a pilot signal.
A data converting apparatus for word-converting an r-bit first dataword to an m-bit second dataword (r<m) and converting the word-converted m-bit second dataword to an n-bit codeword (m<n) comprising:
- means for dividing a sequence of first datawords into groups of x bits and x/r first datawords where x is the least common multiple of r and m;
- means for dividing an arbitrary first dataword of each said group into r/(x/m) bit first dataword portions;
- and
- means for forming the m-bit dataword by appending an r/(x/m)-bit first dataword portion to each remaining one of said x/r first datawords in each said group.
1 more element
A recording/reproducing apparatus for digital data, comprising:
- means for, when a plurality of data groups are recorded on a medium, recording each data group in respective divided areas each said data group including a plurality of datawords;
- means for converting each m-bit dataword to an n-bit (n>m) first codeword having a finite CDS (codeword digital sum);
- and
- means for generating an n+k-bit second codeword, where k is an integer greater than zero, the CDS of said second codeword being selected by a DSV (digital sum variation) control signal by appending a dummy k-bit to said first codeword so that a DSV of a sequence of said second codewords varies in synchronization with the DSV control signal, which has a same period as that of a pilot signal and instructs the DSV variation direction of said sequence of said second codewords, to produce a tracking control pilot signal;
- and
- wherein said tracking control pilot signal is generated in at least one or more data group areas.
3 more elements
A method of converting r-bit first datawords into m-bit second datawords where r/s less than m and subsequently into n-bit codewords, each of said datawords having a most significant bit (MSB) side and a least significant bit (the) side comprising:
- a) dividing a sequence of r-bit first datawords into groups of x bits and x/r first datawords, where x is the least common multiple of r and m;
- b) dividing one of said first datawords into r/(x/m)-bit first dataword portions;
- c) associating an r/(x/m)-bit first dataword portion with each of the remaining ones of said first datawords within each said group to develop m-bit second datawords, said step c) of associating placing every r/(x/m)-bit first dataword portion on the same one of said MSB or LSB side of the remaining ones of said first datawords within each said group.
A method of storing data in an m-bit dataword string as codewords encoded on tracks of a magnetic medium, comprising the steps of:
- a) converting m-bit datawords into a corresponding less than n bit codewords, at least some of said m-bit datawords being mapped into first and second less than n bit codewords having complementary CDSs (codeword digital sums);
- b) adding at least one additional bit to one end of each said less than n bit codewords to form an n-bit codeword including,
- i) developing a DSV (digital sum variation) control signal to control the DSV to a desired value,
- ii) developing the at least one additional bit under control of said DSV control signal,
- iii) adding the at least one additional bit to said less than n bit codeword to produce an n-bit codeword having a known CDS which produces a desired amount of change in DSV, said step b) adding a pilot signal to said data.
2 more elements
A method of storing data in an m-bit dataword string as codewords encoded on tracks of a magnetic medium, comprising the steps of:
- a) converting m-bit datawords into a corresponding less than n bit codewords, at least some of said m-bit datawords being mapped into first and second less than n bit codewords having different known CDSs (codeword digital sums);
- b) adding at least one additional bit to one end of each said less than n bit codewords to form an n-bit codeword, said step b) of adding being responsive to a DSV (digital sum variation) control signal to produce a periodically varying DSV as a pilot signal, said step b) embedding a pilot signal in the digital data signal by periodically varying the DSV of the codeword string by selecting between values of said at least one additional bit which produce n-bit codewords having complementary CDSs.
A method of storing data in an m-bit dataword string as codewords encoded on tracks of a magnetic medium, comprising the steps of:
- a) converting m-bit datawords into a corresponding less than n bit codewords, at least some of said m-bit datawords being mapped into first and second less than n bit codewords having complementary CDSs (codeword digital sums);
- b) during first portions of each track, selecting between said first and second less than n bit codewords so as to minimize dispersion and recording said selected less than n-bit codewords on said track;
- c) during second portions of each track, adding at least one additional bit to one end of each said less than n bit codewords to form an n-bit codeword including,
- i) developing a DSV (digital sum variation) control signal to control the DSV to a desired value,
- ii) developing the at least one additional bit under control of said DSV control signal,
- iii) adding the at least one additional bit to said less than n bit codeword to produce an n-bit codeword having a known CDS which produces a desired amount of change in DSV and
- iv) recording said n-bit codewords on said track said step c) adding a pilot signal to said data in said second portions of said track.
4 more elements
A method of converting r-bit first datawords into m-bit second datawords, where r/s less than m, and into n-bit codewords, comprising the steps of:
- a) dividing each m-bit dataword into m1-bit and m2-bit dataword portions where a m1-bit dataword portion corresponds to a first dataword and where a m2-bit dataword portion corresponds to at least a portion of another first dataword;
- b) assigning to each m-bit dataword having m1-bit and m2-bit dataword portions first and second n-bit codewords each having n1-bit and n2-bit dataword portions corresponding to said m1-bit and m2 bit codeword portions, respectively, said first and second n-bit codewords having different CDSs (codeword digital sums) and forming n-bit codeword pairs, the possible number of codeword pairs which adhere to any run length limitation being sufficient to specify all possible said datawords, codes of at least one of said n1-bit and n2-bit codeword portions which adhere to any run length limitation being insufficient to uniquely encode said m1-bit and m2-bit dataword portions, respectively, said step of assigning including,
- i) assigning to each n1-bit codeword portion having a CDS of u, a pair of n2-bit codeword portions having CDSs of v and x respectively, such that u+v and u+x are said different CDSs,
- said step i) first assigning n1-bit codeword portions and n2-bit codeword portions to said m1-dataword portions and said m2-bit dataword portions in unique one to one mappings, where possible, thereby minimizing error propagation between said n1-bit and n2-bit codeword portions,
- where said unique one to one mappings to n1-bit and n2-bit codeword portions are not possible, said step i) subsequently assigning unique combinations of n1-bit and n2-bit codeword portions to the m1-bit and m2-bit dataword combinations so that said n1-bit codeword portion must be known to decode the n2-bit codeword portion, or vice versa.
2 more elements
An apparatus for storing data in an m-bit dataword string as codewords encoded on tracks of a magnetic medium, comprising:
- a converter converting m-bit datawords into a corresponding less than n bit codewords, at least some of said m-bit datawords being mapped into first and second less than n bit codewords having different known CDSs (codeword digital sums);
- and
- developing means for adding at least one additional bit to one end of each said less than n bit codewords to form an n-bit codeword, said adding operation being responsive to a DSV (digital sum variation) control signal to produce a periodically varying DSV as a pilot signal, and said developing means for embedding a pilot signal in the digital data signal by periodically varying the DSV of the codeword string by selecting between values of said at least one additional bit which produce n-bit codewords having complementary CDSs.
An apparatus for converting r-bit first datawords into m-bit second datawords where r/s less than m, and subsequently into n-bit codewords, each of said datawords having a most significant bit (MSB) side and a least significant bit (the) side, comprising:
- first dividing means for dividing a sequence of r-bit first datawords into groups of x bits and x/r first datawords, where x is the least common multiple of r and m, and for dividing one of said first datawords into r/(x/m)-bit first dataword portions;
- and
- associating means for associating an r/(x/m)-bit first dataword portion with each of the remaining ones of said first datawords within each said group to develop m-bit second datawords, said associating means placing every r/(x/m)-bit first dataword portion on the same one of said MSB or LBS side of the remaining ones of said first datawords within each said group.
An apparatus for storing data in an m-bit dataword string as codewords encoded on tracks of a magnetic medium, comprising:
- a converter converting m-bit datawords into a corresponding less than n codewords, at least some of said m-bit datawords being mapped into first and second less than n bit codewords having complementary CDSs (codeword digital sums);
- developing means for adding at least one additional bit to one end of each said less than n bit codewords to form an n-bit codeword, for developing a DSV (digital sum variation) control signal to control the DSV to a desired value, for developing the at least one additional bit under control of said DSV control signal, for adding the at least one additional bit to said less than n bit codeword to produce an n-bit codeword having a known CDS which produces a desired amount of change in DSV and for adding a pilot signal to said data.
An apparatus for storing data in an m-bit dataword string as codewords encoded on tracks of a magnetic medium, comprising:
- a converter converting m-bit datawords into a corresponding less than n bit codewords, at least some of said m-bit datawords being mapped into first and second less than n bit codewords having complementary CDSs (codeword digital sums);
- a selector, during first portions of each track, selecting between said first and second less than n bit codewords so as to minimize dispersion and recording said selected less than n-bit codewords on said track;
- and
- developing means, during second portions of each track, for adding at least one additional bit to one end of each said less than n bit codewords to form an n-bit codeword, for developing a DSV (digital sum variation) control signal to control the DSV to a desired value, for developing the at least one additional bit under control of said DSV control signal, for adding the at least one additional bit to said less than n bit codeword to produce an n-bit codeword having a known CDS which produces a desired change in DSV, and said developing means including a recorder recording said n-bit codewords on said track;
- and wherein
- said developing means adds a pilot signal to said data in said second portions of said track.
3 more elements
A data conversion method for converting an m-bit dataword to a codeword consisting of a greater number of bits than m, comprising the steps of:
- a) converting each m-bit dataword into an n-bit codeword of codeword digital sum=0, +2, or -2;
- and
- b) adding at least one bit to each n-bit codeword produced by said step a) of converting to control the DSV to a desired value to produce a pilot signal.
Dependencies are inferred from the claim text.