Data encoding and demodulation system

A method of storing data in a storage device in the form of demodulation code words generated from an input string of data bits using a rate 1/2, run-length limited d=2, k=7 code, the method including the steps of:

• A. retaining in a buffer a predetermined number of bits of a previous demodulation code word, the retained bits being the code word bits which are at the end of the demodulation code word to which a next demodulation code word is to be appended;
• B. encoding the right-most bits of the input string to generate demodulation code words and preliminary code words in accordance with the following:
• ______________________________________ DATA BITS ______________________________________ DEMODULATION CODE WORD 01 0100 111 100100 0000 10000001 PRELIMINARY CODE WORD 00 000X 10 100X 011 10000X ______________________________________
• where the right-most bits of the data and the code words are the first in time;
• C. for each preliminary code word examining a predetermined number of the bits retained in the buffer,
• i. if the bits match a predetermined pattern, appending to the beginning of the preliminary code word a ONE bit to form a demodulation code word,
• ii. if the bits do not match the predetermined pattern, appending a ZERO bit to the beginning of the preliminary code word to form a demodulation code word,
• D. retaining in the buffer a predetermined number of bits of the demodulation code word formed in steps B and/or C, the retained bits being the demodulation code word bits which are at the end of the demodulation code word to which a next demodulation code word is to be appended, and eliminating from the buffer the bits of the previous demodulation code word;
• E. transmitting the demodulation code word to a storage device and appending the demodulation code word to the previous demodulation code word in the storage device;
• F. removing from the input string the data bits encoded in steps B and/or C;
• and
• G. repeating steps C-F until the input string has been encoded.

A method of retrieving, demodulation and decoding a data signal representing data which has been encoded in accordance with the following d=2, k=7 run-length-limited code:

• ______________________________________ DATA BITS DEMODULATION CODE WORD ______________________________________ 00 000X 01 0100 10 100X 011 10000X 111 100100 0000 1000000X ______________________________________
• where X is either a ONE or a ZERO, as appropriate to preserve the run-length of the code and the right-most bits of the data and the code words are the first in time, said method including the steps of:
• A. retrieving the data signal from a data storage device;
• B. synchronizing to the data signal and assigning bit values to the signal to produce encoded data;
• C. decoding the bits of the encoded data in groups as demodulation code words to reproduce data bits by--
• i. setting the first two bits of encoded data to ZEROS;
• ii. comparing the first eight bits of the encoded data with the eight-bit demodulation code word 10000000;
• iii. if the bits of the encoded data match the demodulation code word, decoding the eight bits to produce associated data bits;
• iv. if the eight bits of the encoded data do not match the demodulation code word, comparing the first six bits of the encoded data with the six-bit demodulation code words;
• v. if the first six bits of the encoded data match a demodulation code word, decoding the six bits of the encoded data and producing associated data bits;
• vi. if the six encoded bits do not match a demodulation code word, comparing the first four bits of the encoded data with the four-bit demodulation code words and if they match, decoding the four bits of the encoded and producing associated data bits;
• vii. if the first four bits of encoded data do not match a demodulation code word, asserting an error signal indicating an error in the first two data bits;
• D. transmitting the data bits or the error signal, respectively, to a device requesting the data;
• and
• E. repeating steps A--D until the data corresponding to the data signal is decoded.

A data storage system for storing data in the form of demodulation code words generated from an input string of data bits using a rate 1/2m, run-length-limited d=2, k=7 code, the system including:

• A. a buffer for retaining a predetermined number of bits of a previous demodulation code word, the retained bits being the demodulation code word bits which are at the end of the demodulation code word to which a next demodulation code word generated by the system is to be appended;
• B. an encoder for encoding the right-most bits of the input string, the encoder including--
• i. means for generating demodulation code words and preliminary code words in accordance with the following:
• ______________________________________ DATA BITS ______________________________________ DEMODULATION CODE WORD 01 0100 111 100100 PRELIMINARY CODE WORD 00 000X 10 100X 011 10000X 0000 1000000X ______________________________________
• where the right-most bits of the data and the code words are the first in time;
• and
• ii. means for forming a demodulation code word from a preliminary code word, the means examining, for each preliminary code word, a predetermined number of the bits retained in the buffer and appending to the beginning of the preliminary code word a ONE bit if the predetermined number of bits match a first pattern, or a ZERO bit if the predetermined number of bits do not match the first pattern,
• the encoder removing from the input string the encoded data bits;
• C. means for sending to the buffer a predetermined number of bits of the demodulation code word generated by the encoder, the bits being the demodulation code word bits which are at the end of the demodulation code word to which a next demodulation code word generated by the encoder is to be appended, the buffer retaining the bits of the generated demodulation code word and eliminating the bits of the previous demodulation code word;
• E. transmitting means for transmitting the demodulation code word;
• and
• F. a storage device for receiving the demodulation code word from the transmitting means, the storage device appending the demodulation code word to the previous demodulation code words and storing them on a storage medium in the form of a data signal;
• the system repeatedly encoding the remaining data bits until the entire input string has been encoded.

A data storage system for storing data in the form of demodulation code words generated from an input string of data bits using a rate 1/2, run-length-limited d=2, k=7 code, the system including:

• A. a buffer for retaining a predetermined number of bits of a previous demodulation code word, the retained bits being the demodulation code word bits which are at the end of the demodulation code word to which a next demodulation code word generated by the system is to be appended;
• B. an encoder for encoding the right-most bits of the input string, the encoder including--
• i. means for generating demodulation code words and preliminary code words in accordance with the following:
• ______________________________________ DATA BITS ______________________________________ DEMODULATION CODE WORD 01 0100 111 100100 0000 10000001 PRELIMINARY CODE WORD 00 000X 10 100X 011 10000X ______________________________________
• where the right-most bits of the data and the code words are the first in time, and
• ii. means for forming a demodulation code word from a preliminary code word, the means examining, for each preliminary code word, a predetermined number of the bits retained in the buffer and appending to the beginning of the preliminary code word a ONE bit if the predetermined number of bits match a predetermined pattern, or a ZERO bit if the predetermined number of bits do not match the predetermined pattern,
• the encoder removing from the input string the encoded data bits;
• C. means for sending to the buffer a predetermined number of bits of the demodulation code word generated by the encoder, the bits being the demodulation code word bits which are at the end of the demodulation code word to which a next demodulation code word generated by the encoder is to be appended, the buffer retaining the bits of the generated code word and eliminating the bits of the previous code word;
• E. transmitting means for transmitting the demodulation code word;
• and
• F. a storage device for receiving the demodulation word from the transmitting means, the storage device appending the demodulation code word to the previous demodulation code words and storing them on a storage medium in the form of a data signal;
• the system repeatedly encoding the remaining data bits until the entire input string has been encoded.

A data demodulation system for demodulating and decoding a data signal representing data which has been encoded in accordance with the following d=2, k=7 run-length-limited code:

• ______________________________________ DATA BITS DEMODULATION CODE WORD ______________________________________ 00 000X 01 0100 10 100X 011 10000X 111 100100 0000 1000000X ______________________________________
• where X is either a ONE or a ZERO, as appropriate to preserve the run-length of the code and the right-most bits of the data and the code words are the first in time, said method including the steps of:
• A. data retrieval means for retrieving the data signal from a data storage device;
• B. synchronzing means for synchronizing to the data signal and assigning bit values to the signal to produce encoded data;
• C. a decoder for decoding the bits of the encoded data in groups as demodulation code words to reproduce data bits, the decoder including--
• i. means for setting the first two bits of the encoded data to ZEROS;
• ii. comparing means for comparing the first eight bits of the encoded data with the eight-bit demodulation code word 10000000, the comparing means comparing the first six bits of the encoded data with the six-bit demodulation code words, if the eight bits do not match the code word, and if the six encoded bits do not match a demodulation code word, the comparator comparing the first four bits of the encoded data with the four-bit demodulation code words;
• iii. means for decoding the encoded data bits and producing associated data bits if the comparator determines that the bits match a demodulation code word;
• iv. error signal means for asserting an error signal indicating an error in the first two data bits if the first four bits of encoded data do not match a demodulation code word;
• the decoder continuing to decode the bits of the encoded data as demodulation code words until the data signal retrieved from the data storage device is decoded;
• and
• D. transmitting means for transmitting the decoded data bits or the error signal, respectively, to a device requesting the data.

A data demodulation system for demodulating and decoding a data signal representing data which has been encoded in accordance with the following d=2, k=7 run-length-limited code:

• ______________________________________ DATA BITS DEMODULATION CODE WORD ______________________________________ 00 000X 01 0100 10 100X 011 10000X 111 100100 0000 10000001 ______________________________________
• where X is either a ONE or a ZERO, as appropriate to preserve the run-length of the code and the right-most bits of the data and the code words are the first in time, the system including:
• A. data retrieval means for retrieving the data signal from a data storage device;
• B. synchronizing means for synchronizing to the data signal and assigning bit values to the signal to produce encoded data;
• C. a decoder for decoding the bits of the encoded data in groups as demodulation code words to reproduce data bits, the decoder including--
• i. first comparing means for comparing the first eight bits of the encoded data with the eight-bit demodulation code word 10000001;
• ii. first decoding means for decoding the first eight bits as a demodulation code word to produce four data bits if the comparator determines that the eight bits match the eight-bit-demodulation code word;
• iii. means for setting the first two bits of encoded data to ZEROS if the first comparing means does not determine a match;
• iv. second comparing means for comparing the first six bits of the encoded data with the six-bit demodulation code words, and if the six encoded bits do not match a code word, comparing the first four bits of the encoded data with the four-bit demodulation code words;
• iii. means for decoding the encoded data bits and producing associated data bits if the second comparator determines that the bits match the code word;
• iv. error signal means for asserting an error signal indicating an error in the first two data bits if the first four bits of encoded data do not match a demodulation code word;
• the decoder continuing to decode the bits of the encoded data as demodulation code words until the data signal retrieved from the data storage device is decoded;
• and
• D. transmitting means for transmitting the decoded data bits or the error signal, respectively, to a device requesting the data.

A method of demodulating and decoding a data signal representing data which has been encoded in accordance with the following d=2, k=7 run-length-limited code:

• ______________________________________ DATA BITS DEMODULATION CODE WORD ______________________________________ 00 000X 01 0100 10 100X 011 10000X 111 100100 0000 10000001 ______________________________________
• where X is either a ONE or a ZERO, as appropriate to preserve the run-length of the code and the right-most bits of the data and the code words are the first in time, said method including the steps of:
• A. retrieving the data signal from a data storage device;
• B. synchronizing to the data signal and assigning bit values to the signal to produce encoded data;
• C. decoding the bits of the encoded data in groups as demodulation code words to reproduce data bits by--
• i. comparing the first eight bits of the encoded data with the eight-bit code word 10000001;
• ii. if the bits match the code word, decoding the eight bits to produce associated data bits;
• iii. if the eight bits do not match the code word, setting the first two bits of encoded data to ZEROS;
• iv. comparing the first six bits of the encoded data with the six-bit demodulation code words;
• v. if the first six bits of the encoded data match a code word, decoding the six bits and producing associated data bits;
• iv. if the six encoded bits do not match a demodulation code word, comparing the first four bits of the encoded data with the four-bit demodulation code words and if they match, decoding the four bits and producing associated data bits;
• vii. if the first four bits of encoded data do not match a demodulation code word, asserting an error signal indicating an error in the first two data bits;
• D. transmitting the decoded data bits or the error signal, respectively, to a device requesting the data;
• and
• E. repeating steps A-D until the encoded data corresponding to the data signal is decoded.

A method of synchronizing to, demodulating and decoding a data signal representing data which has been encoded in accordance with the following d=2, k=7 run-length-limited code:

• ______________________________________ DATA BITS DEMODULATION CODE WORD ______________________________________ 00 000X 01 0100 10 100X 011 10000X 111 100100 0000 1000000X ______________________________________
• where X is either a ONE or a ZERO, as appropriate to preserve the run-length of the code and the right-most bits of the data and the code words are the first in the time, said method including the steps of:
• A. retrieving the data signal from a data storage device;
• B. synchronizing to the data signal and assigning bit values to the signal by locating at least one of the following patterns in the bit values:
• i. a single bit pattern of a ONE in an odd bit position followed by three ZEROS;
• ii. a ONE in an odd bit position followed by four or more ZEROS;
• iii. a bit pattern 00000100 starting at an odd bit position;
• or
• iv. a bit pattern 01000100 starting at an odd bit position;
• C. decoding the bit values in groups as demodulation code words to reproduce data bits by--
• i. setting the first two bits of encoded data to ZEROS;
• ii. comparing the first eight bits of the encoded data with the eight-bit code word 10000000;
• iii. if the bits match the code word, decoding the eight bits and producing associated data bits;
• iv. if the eight bits do not match the code word, comparing the first six bits of the encoded data with the six-bit demodulation code words;
• v. if the first six bits of the encoded data match a demodulation code word, decoding the six bits and producing associated data bits;
• vi. if the six encoded bits do not match a demodulation code word, comparing the first four bits of the encoded data with the four-bit demodulation code words and if they match, decoding the four bits and producing associated data bits;
• vii. if the first four bits of encoded data do not match a demodulation code word, asserting an error signal indicating an error in the first two data bits;
• D. transmitting the decoded data bits or the error signal, respectively, to a device requesting the data;
• and
• E. repeating steps A-D until the encoded data corresponding to the data signal is decoded.

A method of synchronizing to, demodulating and decoding a data signal representing data which has been encoded in accordance with the following d=2, k=7 run-length-limited code:

• ______________________________________ DATA BITS DEMODULATION CODE WORD ______________________________________ 00 000X 01 0100 10 100X 011 10000X 111 100100 0000 10000001 ______________________________________
• where X is either a ONE or a ZERO, as appropriate to preserve the run-length of the code and the right-most bits of the data and the code words are the first in time, said method including the steps of:
• A. retrieving the data signal from a data storage device and assigning bit values to produce encoded data;
• B. synchronizing to the data signal to the signal by locating at least one of the following patterns in the bit values:
• i. a single bit pattern of a ONE in an odd bit position followed by three ZEROS;
• ii. a ONE in an odd bit position followed by four or more ZEROS;
• iii. a bit pattern 00000100 starting at an odd bit position;
• or
• iv. a bit pattern 01000100 starting at an odd bit position;
• c. decoding the bits of the encoded data in groups as demodulation code words to reproduce data bits by--
• i. setting the first two bits of encoded data to ZEROS;
• ii. comparing the first eight bits of the encoded data with the eight-bit code word 10000000;
• iii. if the bits match the code word, decoding the eight bits and producing associated data bits;
• iv. if the eight bits do not match the code word, comparing the first six bits of the encoded data with the six-bit demodulation code words;
• v. if the first six bits of the encoded data match a demodulation code word, decoding the six bits and producing associated data bits;
• vi. if the six encoded bits do not match a demodulation code word, comparing the first four bits of the encoded data with the four-bit demodulation code words and if they match, decoding the four bits and producing associated data bits;
• vii. if the first four bits of encoded data do not match a demodulation code word, asserting an error signal indicating an error in the first two data bits;
• D. transmitting the decoded data bits or the error signal, respectively, to a device requesting the data;
• and
• E. repeating steps A-D until the encoded data corresponding to the data signal is decoded.

A data demodulation system for synchronizing to, demodulating and decoding a data signal representing data which has been encoded in accordance with the following d=2, k=7 run-length-limited code:

• ______________________________________ DATA BITS DEMODULATION CODE WORD ______________________________________ 00 000X 01 0100 10 100X 011 10000X 111 100100 0000 1000000X ______________________________________
• where X is either a ONE or a ZERO, as appropriate to preserve the run-length of the code and the right-most bits of the data and the code words are the first in time, the system including:
• A. data retrieval means for retrieving the data signal from a data storage device and assigning bit values to produce encoded data;
• B. synchronzing means for synchronizing to the data signal to the signal, the synchronizing means determining the beginnings of code words by locating at least one of the following patterns in the encoded data bits:
• i. a single bit pattern of a ONE in an odd bit position followed by three ZEROS;
• ii. a ONE in an odd bit position followed by four or more ZEROS;
• iii. a bit pattern 00000100 starting at an odd bit position;
• or
• iv. a bit pattern 01000100 starting at an odd bit position;
• the synchronizing means asserting an error signal if one of the bit patterns is not located;
• C. a decoder for decoding the bits of the encoded data in groups as demodulation code words to reproduce data bits, the decoder including--
• i. first comparing means for comparing the first eight bits of the encoded data with the eight-bit demodulation code word 10000001;
• ii. first decoding means for decoding the first eight bits to produce four data bits if the comparator determines that the eight bits match the eight-bit demodulation code word;
• iii. means for setting the first two bits of encoded data to ZEROS if the first comparing means does not determine a match;
• iv. second comparing means for comparing the first six bits of the encoded data with the six-bit demodulation code words, and if the six encoded bits do not match a code word comparing the first four bits of the encoded data with the four-bit demodulation code words;
• iii. means for decoding the encoded data bits and producing associated data bits if the second comparator determines that the bits match a demodulation code word;
• iv. error signal means for asserting an error signal indicating an error in the first two data bits if the first four bits of encoded data do not match a demodulation code word;
• the decoder continuing to decode the encoded data as demodulation code words until the data signal retrieved from the data storage device is decoded;
• and
• D. transmitting means for transmitting the decoded data bits or the error signal, respectively, to a device requesting the data.

A data demodulation system for synchronizing to, demodulating and decoding a data signal representing data which has been encoded in accordance with the following d=2, k=7 run-length-limited code:

• ______________________________________ DATA BITS DEMODULATION CODE WORD ______________________________________ 00 000X 01 0100 10 100X 011 10000X 111 100100 0000 10000001 ______________________________________
• where X is either a ONE or a ZERO, as appropriate to preserve the run-length of the code and the right-most bits of the data and the code words are the first in time, the system including:
• A. data retrieval means for retrieving the data signal from a data storage device and assigning bit values to the signal to produce encoded data;
• B. synchronizing means for synchronizing to the data signal, the synchronizing means determining the beginnings of code words by locating at least one of the following patterns in the encoded data bits:
• i. a single bit pattern of a ONE in an odd bit position followed by three ZEROS;
• ii. a ONE in an odd bit position followed by four or more ZEROS;
• iii. a bit pattern 00000100 starting at an odd bit position;
• or
• iv. a bit pattern 01000100 starting at an odd bit position;
• the synchronizing means asserting an error signal if one of the bit patterns is not located;
• C. a decoder for decoding the bits of the encoded data in groups as demodulation code words to reproduce data bits, the decoder including--
• i. first comparing means for comparing the first eight bits of the encoded data with the eight-bit demodulation code word 10000001;
• ii. first decoding means for decoding the first eight bits to produce four data bits if the comparator determines that the eight bits match the eight-bit demodulation code word;
• iii. means for setting the first two bits of encoded data to ZEROS if the first comparing means does not determine a match;
• iv. second comparing means for comparing the first six bits of the encoded data with the six-bit demodulation code words, and if the six encoded bits do not match a demodulation code word, comparing the first four bits of the encoded data with the four-bit demodulation code words;
• iii. means for decoding the encoded data bits and producing associated data bits if the second comparator determines that the bits match a demodulation code word;
• iv. error signal means for asserting an error signal indicating an error in the first two data bits if the first four bits of encoded data do not match a demodulation code word;
• the decoder continuing to decode the bit values as demodulation code words until the data signal retrieved from the data storage device is decoded;
• and
• D. transmitting means for transmitting the decoded data bits or the error signal, respectively, to a device requesting the data.