Method of modulating and demodulating digital data and digital data modulator/demodulator

A method of modulating digital data to be used for transmitting or recording N-bit data, comprising steps of:

• inputting an N-bit data;
• converting the input N-bit data into an M+K-bit data selected out of a group of L.times.2.sup.M M+K-bit data according to a predetermined rule, the group of L.times.2.sup.M M+K-bit data being obtained by adding K-bit error correction checking symbols generated on the basis of L error correcting generation polynomials to M-bit data (N<M) on a one by one basis and in terms of Hamming distance greater than a predetermined value;
• and
• outputting the converted M+K-bit data.

A method of modulating digital data to be used for transmitting or recording N-bit data, comprising steps of:

• inputting an N-bit data;
• converting by means of a converting method selected out of R different converting methods the input N-bit data into an M.sub.i +K.sub.i -bit data selected out of a group of 2.sup.Mi M.sub.i +K.sub.i -bit data according to a predetermined rule, the group of 2.sup.Mi M.sub.i +K.sub.i -bit data being obtained by adding K.sub.i -bit error correction checking symbols (K.sub.i being 0 or a positive integer) to M.sub.i -bit data (N<M.sub.i ;
• i=0, 1, 2, 3, . . . , R-1) on a one by one basis;
• and
• outputting the converted M.sub.i +K.sub.i -bit data along with information data showing the selected converting method.

A method of demodulating an M+K-bit digital data into an N-bit data, where the M+K-bit digital data has been obtained by a digital data modulating method of converting the N-bit into an M+K-bit data selected out of a group of L.times.2.sup.M M+K-bit data according to a predetermined rule, the group of L.times.2.sup.M M+K-bit data being obtained by adding K-bit error correction checking symbols generated on the basis of L error correcting generation polynomials to 14-bit data (N<M) on a one by one basis and in terms of Hamming distance greater than a predetermined value, said method of demodulating comprising steps of:

• carrying out one of an error correcting operation and an error detecting operation on the M+K-bit data corresponding to each of the L error correction generation polynomials;
• demodulating the L M+K-bit data subjected to the one of the error correcting operation and the error detecting operation into L N-bit data;
• and
• selecting a most likely N-bit data out of the demodulated L N-bit data and outputting the selected N-bit data with corresponding demodulation error identifying information.

A method of demodulating an M.sub.i +K.sub.i -bit digital data into an N-bit data, where the M.sub.i +K.sub.i -bit digital data has been obtained by a digital data modulating method of converting by means of a converting method selected out of R different converting methods the input N-bit into an M.sub.i +K.sub.i -bit data selected out of a group of 2.sup.Mi M.sub.i +K.sub.i -bit data according to a predetermined rule, the group of 2.sup.Mi M.sub.+K.sub.i -bit data being obtained by adding K.sub.i -bit error correction checking symbols (K.sub.i being 0 or a positive integer) to M.sub.i -bit data (N<M.sub.i ;

• i=0, 1, 2, 3, . . . , R-1) on a one by one basis, and where the digital data modulating method included a step of outputting the obtained M.sub.i +K.sub.i -bit digital data along with information data showing the selected converting method, said method of demodulating comprising steps of:
• extracting the information data showing the selected converting method;
• extracting the M.sub.i +K.sub.i,-bit data according to the extracted information data;
• and
• demodulating the extracted M.sub.i +K.sub.i -bit data into the N-bit data according to the extracted information data.

A digital data modulator to be used for transmitting or recording N-bit data, comprising:

• an input terminal for inputting an N-bit data;
• a converting section for converting the input N-bit data into an M+K-bit data selected out of a group of 2.sup.M M+K-bit data according to a predetermined rule, the group of 2.sup.M M+K-bit data being obtained by adding a K-bit error correction checking symbol to M-bit data (N<M);
• and
• an output terminal for outputting the converted M+K-bit data.

A digital data modulator to be used for transmitting or recording N-bit data, comprising:

• an input terminal for inputting an N-bit data;
• a converting section for converting the input N-bit data into an M+K-bit data selected out of a group of L.times.2.sup.M M+K-bit data according to a predetermined rule, the group of L.times.2.sup.M M+K-bit data being obtained by adding K-bit error correction checking symbols generated on the basis of L error correcting generation polynomials to M-bit data (N<M) on a one by one basis and in terms of Hamming distance greater than a predetermined value;
• and
• an output terminal for outputting the converted M+K-bit data.

A digital data modulator to be used for transmitting or recording N-bit data, comprising:

• an input terminal for inputting an N-bit data;
• a converting section for converting by means of a converting method selected out of R different converting methods the input N-bit data into an M.sub.i +K.sub.i -bit data selected out of a group of 2.sup.Mi M.sub.i +K.sub.i -bit data according to a predetermined rule, the group of 2.sup.Mi M.sub.i +K.sub.i -bit data being obtained by adding K.sub.i -bit error correction checking symbols (K.sub.i =0, 1, 2, 3, . . . ) to M.sub.i -bit data (N<M.sub.i ;
• i=0, 1, 2, 3, . . . , R-1) on a one by one basis;
• and
• an output terminal for outputting the converted M.sub.i +K.sub.i -bit data along with information data showing the selected converting method.

A digital data demodulator for demodulating an M+K-bit digital data into an N-bit data, where the M+K digital data has been obtained by a digital data modulating method of converting the N-bit into an M+K-bit data selected out of a group of L.times.2.sup.M M+K-bit data according to a predetermined rule, the group of L.times.2.sup.M M+K-bit data being obtained by adding K-bit error correction checking symbols generated on the basis of L error correcting generation polynomials to M-bit data (N<M) on a one by one basis and in terms of Hamming distance greater than a predetermined value, said demodulator comprising:

• an error correcting section for carrying out one of an error correcting operation and an error detecting operation on the M+K-bit data corresponding to each of the L error correction generation polynomials;
• a demodulating section for demodulating the L M+K-bit data subjected to the one of the error correcting operation and the error detecting operation into L N-bit data;
• and
• an output section for selecting a most likely N-bit data out of the demodulated L N-bit data and outputting the selected N-bit data with corresponding demodulation error identifying information.

A digital data demodulator for demodulating an M.sub.i +K.sub.i -bit digital data into an N-bit data, where the M.sub.i +K.sub.i -bit digital data has been obtained by a digital data modulating method of converting by means of a converting method selected out of R different converting methods the input N-bit into an M.sub.i +K.sub.i -bit data selected out of a group of 2.sup.Mi M.sub.i +K.sub.i -bit data according to a predetermined rule, the group of 2.sup.Mi M.sub.i +K.sub.i -bit data being obtained by adding K.sub.i,-bit error correction checking symbols (K.sub.i being 0 or a positive integer) to M.sub.i -bit data (N<M.sub.i ;

• i=0, 1, 2, 3, . . . , R-1) on a one by one basis, and where the digital data modulating method including a step of outputting the obtained M.sub.i +K.sub.i -bit digital data along with information data showing the selected converting method, said demodulator comprising:
• an information data extracting section for extracting the information data showing the selected converting method;
• a bit data extracting section for extracting the M.sub.i +K.sub.i -bit data according to the extracted information data;
• and
• a demodulating section for demodulating the extracted M.sub.i +K.sub.i -bit data into the N-bit data according to the extracted information data.

A method of modulating digital data to be used for printing and recording an N-bit data on a predetermined medium as an optically readable code pattern, wherein

• the code pattern is formed by arranging a plurality of blocks having a predetermined area adapted to hold a predetermined volume of data, each block comprising:
• a pattern formed by a plurality of dot images arranged in correspondence with the held data;
• a marker arranged with a predetermined positional relationship with the dot image pattern to determine a reference position for reading the dot image pattern;
• and a block address pattern for indicating positions of the blocks of the code pattern;
• and
• when an N-bit data is converted into an M-bit data selected out of a group of 2.sup.M M-bit data (N<M) according to a predetermined rule and data values of the M-bit data are caused to correspond to respective dot images of predetermined colors, a total number of dot images contained in each of the blocks is made equal to a value obtained by multiplying M by an integer.