Code conversion method and apparatus, code recording medium, code recording apparatus and code reproducing apparatus

A code conversion method comprising the steps of:

• scrambling an input main data unit based on any of plural types of pseudo-random number sequences;
• modulating the scrambled main data unit based on any of plural types of modulation data;
• producing an output main data unit from the modulated main data unit;
• obtaining a calculated value representing a difference between a number of 0 bits and a number of 1 bits included in the output main data unit;
• and
• selecting any of the modulation data dependent upon the calculated value,
• wherein the code conversion method further includes the steps of:
• determinant whether or not an absolute value of the calculated value has exceeded a predetermined threshold value;
• newly selecting another pseudo-random number sequence used for the step of scrambling if it is determined that the absolute value of the calculated value has exceeded the predetermined threshold value;
• and
• re-scrambling the input main data unit based on the newly selected pseudo-random number sequence.

A code conversion apparatus comprising:

• storage means for storing an input main data unit;
• scrambling means for scrambling the main data unit stored in the storage means based on any of plural types of pseudo-random number sequences;
• data and producing an output main data unit from the modulated main data unit;
• arithmetic means for obatining a calculated value representing a difference between a number of 0 bits and a number of 1 bits included in the output main data unit which has been produced by the modulation means;
• comparison means for determining whether or not the calculated value obtained by the arithmetic means is within a predetermined tolerance range;
• and
• control means for instructing the scrambling means to newly select another pseudo-random number sequence and to re-scramble the main data units stored in the storage means if the comparison means determines that the calculated value is out of the tolerance range.

A code conversion apparatus comprising:

• storage means for storing an input main data unit;
• scrambling means for scrambling the main data unit stored in the storage means based on any of plural types of pseudo-random number sequences;
• detection means for detecting a location of the main data unit which has been read out from the storage means;
• modulation means for modulating the scrambled main data unit based on any of plural types of modulation data and producing an output main data unit from the modulated main data unit;
• arithmetic mean for obtaining a calculated value representing a difference between a number of 0 bits and a number of 1 bits included in the output main data unit;
• comparison means for determining whether or not the calculated value obtained by the arithmetic means is within a predetermined tolerance range;
• and
• control means for instructing the scrambling means to newly select another pseudo-random number sequence and then to re-scramble a part of the main data units located prior to the location of the main data unit which has been detected by the detection means at a point in time when the comparison means has determined that the calculated value is out of the tolerance range.

A code conversion apparatus comprising:

• storage means for storing an input main data unit;
• scrambling means for scrambling the main data unit stored in the storage means based on any of plural types of pseudo-random number sequences;
• detection means for detecting a location of each frame of the main data unit stored in the storage means, every time each said frame is sequentially read out from the storage means;
• modulation means for modulating the scrambled main data unit based on any of plural types of modulation data and producing an output main data unit from the modulated main data unit;
• arithmetic means for obtaining a calculated value representing a difference between a number of 0 bits and a number of 1 bits included in the output main data unit;
• comparison means for determining whether or not the calculated value obtained by the arithmetic means is within a predetermined tolerance range;
• and
• control means for instructing the scrambling means to newly select another pseudo-random number sequence and then to re-scramble a plurality of frames located prior to the frame, the location of which has been detected by the detection means, at a point in time when the comparison means has determined that the calculated value is out of the tolerance range.

A code conversion apparatus comprising:

• storage means for storing at least one sector of input main data units;
• scrambling means for scrambling the at least one sector of main data units stored in the storage means based on any of plural types of pseudo-random number sequences;
• modulation means for modulating the scrambled main data units based on any of plural types of modulation data and producing output main data units from the modulated main data units;
• arithmetic means for obtaining a calculated value representing a difference between a number of 0 bits and a number of 1 bits included in each of the output main data units;
• comprison means for determining whether or not the calculated value obtained by the arithmetic means is within a predetermined tolerance range;
• and
• control means for instructing the scrambling means to newly select another pseudo-random number sequence and then to re-scramble the at least one sector of main data units stored in the storage means if the comparison means has determined that the calculated value is out of the tolerance range.

A code recording medium for recording/reproducing main data thereon/therefrom on a sector basis,

• wherein scramble data and scrambled main data are recorded in every sector,
• and wherein the scramble data is represented by any of initial values of predetermined pseudo-random number sequences for scrambling the main data,
• and wherein each of the pseudo-random number sequences is comprised of a plurality of random numbers beginning with an initial value of the pseudo-random number sequence,
• and wherein the main data has been scrambled by sequentially performing a logical operation on the pseudo-random number sequence representing the scramble data and the main data.

A code recording apparatus for scrambling and recording main data on a sector basis on a recording medium, comprising:

• scramble data generation means for generating scramble data represented by any of a plurality of predetermined pseudo-random number sequences;
• pseudo-random number sequence generation means for generating the pseudo-random number sequences in accordance with the scramble data, each of the pseudo-random number sequences being represented by the scramble data;
• scrambling means for scrambling the main data by sequentially performing a logical operation on the generated pseudo-random number sequence and a sector of main data;
• modulation means for modulating the scrambled main data;
• and
• recording means for recording the modulated main data together with the scramble data onto a sector on the recording medium.

A code recording apparatus for scrambling and recording main data on a sector basis on a recording medium, comprising:

• scramble data generation means for generating scramble data represented by any of a plurality of predetermined pseudo-random number sequences;
• pseudo-random number sequence generation means for generating the pseudo-random number sequences in accordance with the scramble data, each of the pseudo-random number sequences being represented by the scramble data;
• scrambling means for scrambling the main data by sequentially performing a logical operation on the generated pseudo-random number sequence and a sector of main data;
• modulation means for modulating the scrambled main data;
• recording means for recording the modulated main data together with the scramble data onto a sector on the recording medium;
• arithmetic means for obtaining a calculated value representing a difference between a number of 0 bits and a number of 1 bits included in the modulated main data;
• and
• a determination means for determining the calculated value.

A code reproducing apparatus for reproducing main data from a recording medium for recording/reproducing the main data thereon/therefrom on a sector basis, scramble data and scrambled main data being recorded in every sector, the scramble data being represented by any of initial values of predetermined pseudo-random number sequences for scrambling the main data, each of the pseudo-random number sequences including a plurality of random numbers beginning with a unique initial value, and the main data having been scrambled by sequentially performing a logical operation on the pseudo-random number sequence representing the scramble data and the main data, the code reproducing apparatus comprising:

• read means for reading out the scramble data from a sector of the recording medium;
• pseudo-random number sequence generation means for generating a pseudo-random number sequence for descrambling the scrambled main data in accordance with the read out scramble data;
• and
• de-scrambling means for restoring original non-scrambled main data by sequentially performing a logical operation on the pseudo-random number sequence and the sector of main data.

A method for scrambling input data, comprising the steps of:

• generating scramble data having a value which is randomly determined;
• generating a pseudo-random number sequence in accordance with the value of the scramble data;
• and
• generating scrambled data by performing a logical operation on the pseudo-random number sequence and said input data.

A method for recording information onto a recording medium, comprising the steps of:

• generating scramble data having a value which is randomly determined;
• generating a pseudo-random number sequence in accordance with the value of the scramble data;
• generating scrambled data by performing a logical operation on the pseudo-random number sequence and input data;
• and
• recording the scramble data and the scrambled data onto the recording medium.