Digital data recording and reproducing method
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorKousou Takeuchi
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Abstract
A digital data recording and reproducing method in which a digital data sequence is divided into 8-bit digital data sequences. When the divided 8-bit digital data sequences are encoded into 14-bit code, an 8-bit digital data sequence wherein the value of its DSV (digital sum variation) is limited to a predetermined range is selected from two codes which are assigned to correspond to the 8-bit digital data sequence. In the encoding process, the number of "0" bits which are inserted between two "1" bits in the code sequence is restricted to a number of from one to eight so that the DC component in the code sequence can be eliminated. A bit sequence which never arises in two successive 14-bit code words may then be used as a frame synchronizing signal.
Claims8
A digital data recording and reproducing method, comprising the steps of:
- dividing a string of inputted digital data into successive 8-bit information words;
- assigning to each 8-bit information word at least one 14-bit NRZI code word in which the number of "0" bits inserted between two successive "1" bits in each 14-bit NRZI code word is between one and eight, inclusive;
- determining the digital sum variation of the preceding 14-bit NRZI code words forming an NRZI coded waveform representative of successive 8-bit information words in said string of inputted digital data;
- and
- selecting one of said assigned 14-bit NRZI code words to represent the next 8-bit information word divided from said string of inputted digital data as a function of the polarity of an NRZI code word digital sum of said selected one 14-bit NRZI code word and the polarity of the determined digital sum variation sum that said selected one 14-bit NRZI code word tends to decrease the absolute value of the digital sum variation of the NRZI coded waveform.
An apparatus for recording and reproducing digital data, comprising:
- means for dividing a string of inputted digital data into successive 8-bit information words;
- means for assigning to each successive 8-bit information word at least one 14-bit NRZI code word in which the number of "0" bits inserted between two successive "1" bits in each 14-bit code word is between one and eight, inclusive;
- means for issuing a control signal for selecting one of said assigned 14-bit NRZI code words assigned to said 8-bit information words as a function of the polarity of an NRZI code word digital sum of said assigned 14-bit NRZI code words and the polarity of the digital sum variation of the preceding 14-bit NRZI code words forming an NRZI coded waveform representative of successive 8-bit information words in said string of inputted digital data such that said selected one 14-bit NRZI code word tends to decrease the absolute value of the digital sum variation of the NRZI coded waveform;
- and
- means responsive to said control signal for selecting said one assigned 14-bit NRZI code word to represent an inputted 8-bit information word divided from said string of inputted digital data.
Dependencies are inferred from the claim text.