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

Abstract

A code conversion method and apparatus is provided for scrambling and modulating data. The method and apparatus includes scrambling an input main data unit based on any of plural types of pseudo-random number sequences, and modulating the scrambled main data unit based on any of plural types of modulation data. An output main data unit is produced from the modulated main data unit, and 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 is obtained. Any of the modulation data is then selected dependent upon the calculated value. The method and apparatus further includes determining whether or not a variation of the calculated value has exceeded a predetermined threshold, newly selecting another pseudo-random number sequence used for the step of scrambling if it is determined that the variation 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.

1. 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 step of: 
 determining whether or not a variation 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 variation 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.  
 
 
     
     
       2. A code conversion method according to  claim 1 , wherein the step of modulating the scrambled main data unit is performed by a first modulation having M types of modulation data,
 and wherein the step of producing the output main data unit is performed by a second modulation, N types of modulation data out of the M types of modulation data causing an increase of the calculated value.  
 
     
     
       3. A code conversion method according to  claim 2 , wherein, in the step of modulating, the first modulation is a pit position modulation having M types of modulation data,
 and wherein, in the step of producing, the second modulation is a pulse width modulation,  
 and wherein N types of modulation data out of the M types of modulation data causing an increase of the calculated value.  
 
     
     
       4. A code conversion method according to  claim 2 , wherein, in the step of determining, if the variation of the calculated value becomes equal to or larger than the threshold value K during a first period L, an output main data unit having a bit pattern which has caused the increase of the calculated value is included in a plurality of main data units to be output during the first period L,
 and wherein if the pseudo-random number sequence applied to the main data unit which has caused the increase of the calculated value is called a first pseudo-random number sequence, the first pseudo-random number sequence is changed into any of a plurality of predetermined second pseudo-random number sequences,  
 and wherein the plurality of second pseudo-random number sequences are pseudo-random number sequences making it possible to obtain a plurality of main data units not having the bit pattern as the main data units to be produced by the step of re-scrambling and to be output during the first period L at a ratio equal to or larger than (M−N)/M.  
 
     
     
       5. A code conversion method according to  claim 4 , wherein if a period during which a series of output main data units are produced by the step of scrambling using the first pseudo-random number sequence is called a second period H,
 the number of the plurality of second pseudo-random number sequences is at least equal to H/L=J.  
 
     
     
       6. A code conversion method according to  claim 1 , wherein, in the step of determining, if the variation of the calculated value has exceeded the threshold value, a part of the main data units which have been previously input before the point in time and have a predetermined length is re-scrambled after another pseudo-random number sequence is newly selected for the part. 
     
     
       7. A code conversion method according to  claim 1 , further comprising the steps of:
 obtaining a calculated value of an output main data unit corresponding to the input main data unit having a predetermined length;  
 newly selecting another pseudo-random number sequence and re-scrambling the input main data unit if the variation of the calculated value has exceeded the threshold value; and  
 obtaining a pseudo-random number sequence causing the variation of the calculated value to be equal to or smaller than the threshold value.  
 
     
     
       8. 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.  
 
 
     
     
       9. A code conversion method according to  claim 8 , wherein the step of modulating the scrambled main data unit is performed by a first modulation having M types of modulation data,
 and wherein the step of producing the output main data unit is performed by a second modulation,  
 and wherein N types of modulation data out of the M types of modulation data causing an increase of the calculated value.  
 
     
     
       10. A code conversion method according to  claim 9 , wherein, in the step of modulating, the first modulation is a pit position modulation having M types of modulation data,
 and wherein, in the step of producing, the second modulation is a pulse width modulation,  
 and wherein N types of modulation data out of the M types of modulation data causing the increase of the calculated value.  
 
     
     
       11. A code conversion method according to  claim 9 , wherein, in the step of determining, if the absolute value of the calculated value becomes equal to or larger than the threshold value K during a first period L, an output main data unit having a bit pattern which has caused the increase of the calculated value is included in a plurality of main data units to be output during the first period L,
 and wherein if the pseudo-random number sequence applied to the main data unit which has caused the increase of the calculated value is called a first pseudo-random number sequence, the first pseudo-random number sequence is changed into any of a plurality of predetermined second pseudo-random number sequences,  
 and wherein the plurality of second pseudo-random number sequences are pseudo-random number sequences making it possible to obtain a plurality of main data units not having the bit pattern as the main data units to be produced by the step of re-scrambling and to be output during the first period L at a ratio equal to or larger than (M−N)/M.  
 
     
     
       12. A code conversion method according to  claim 11 , wherein if a period during which a series of output main data units are produced by the step of scrambling using the first pseudo-random number sequence is called a second period H,
 the number of the plurality of second pseudo-random number sequences is at least equal to H/L=J.  
 
     
     
       13. A code conversion method according to  claim 8 , wherein, when the absolute value of the calculated value exceeds the threshold value, a part of the main data units which have been previously input before the point in time and have a predetermined length is re-scrambled after another pseudo-random number sequence is newly selected for the part. 
     
     
       14. A code conversion method according to  claim 8 , further comprising the steps of:
 obtaining a calculated value of an output main data unit corresponding to the input main data unit having a predetermined length;  
 newly selecting another pseudo-random number sequence and re-scrambling the input main data unit if the absolute value of the calculated value has exceeded the threshold value; and  
 obtaining a pseudo-random number sequence causing the absolute value of the calculated value to be equal to or smaller than the threshold value.  
 
     
     
       15. 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.  
 
     
     
       16. A code conversion apparatus according to  claim 15 , further comprising recording means for recording output data of the modulation means,
 wherein the control means outputs a conversion failure signal if the comparison means has determined that the calculated value is out of the tolerance range,  
 and wherein the recording means re-starts recording the output data of the modulation means, in response to the conversion failure signal.  
 
     
     
       17. 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.  
 
     
     
       18. A code conversion apparatus according to  claim 17 , further comprising recording means for recording the output main data unit,
 wherein the control means outputs a conversion failure signal if the comparison means has determined that the calculated value is out of the tolerance range,  
 and wherein the recording means re-starts recording the output main data unit, in response to the conversion failure signal.  
 
     
     
       19. 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.  
 
     
     
       20. A code conversion apparatus according to  claim 19 , further comprising recording means for recording the output data of the modulation means,
 wherein the control means outputs a conversion failure signal if the comparison means has determined that the calculated value is out of the tolerance range,  
 and wherein the recording means re-starts recording the output data of the modulation means, in response to the conversion failure signal.  
 
     
     
       21. 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.  
 
     
     
       22. A code conversion apparatus according to  claim 21 , further comprising recording means for recording the output main data units,
 wherein the control means outputs a conversion failure signal if the comparison means has determined that the calculated value is out of the tolerance range,  
 and wherein the recording means re-starts recording the output main data units, in response to the conversion failure signal.  
 
     
     
       23. 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.  
 
     
     
       24. A code recording medium according to  claim 23 , wherein each of the pseudo-random number sequences is a maximum length sequence. 
     
     
       25. A code recording medium according to  claim 23 , wherein the scramble data indicates whether or not a sector of main data is scrambled. 
     
     
       26. A code recording medium according to  claim 23 , wherein the scramble data is set based on the random numbers. 
     
     
       27. A code recording medium according to  claim 23 , wherein the scramble data is set in accordance with how many times main data has been rewritten on the same sector. 
     
     
       28. 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.  
 
     
     
       29. 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.  
 
     
     
       30. A code recording apparatus according to  claim 28 , wherein the pseudo-random number sequence generation means generates the pseudo-random number sequences in accordance with not only the scramble data but also sector identification data for identifying each sector of the recording medium. 
     
     
       31. A code recording apparatus according to  claim 29 , wherein the pseudo-random number sequence generation means generates the pseudo-random number sequences in accordance with not only the scramble data but also sector identification data for identifying each sector of the recording medium. 
     
     
       32. A code recording apparatus according to  claim 28 , wherein the scramble data generation means outputs the respective pseudo-random number sequences in a predetermined order. 
     
     
       33. A code recording apparatus according to  claim 29 , wherein the scramble data generation means outputs the respective pseudo-random number sequences in a predetermined order. 
     
     
       34. A code recording apparatus according to  claim 28 , wherein the scramble data generation means selects each of the pseudo-random number sequences based on the random numbers and then outputs the scramble data representing the selected pseudo-random number sequence. 
     
     
       35. A code recording apparatus according to  claim 29 , wherein the scramble data generation means selects each of the pseudo-random number sequences based on the random numbers and then outputs the scramble data representing the selected pseudo-random number sequence. 
     
     
       36. 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.  
 
     
     
       37. 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.     
     
     
       38. A method according to  claim 37 , wherein the value of the scramble data is randomly determined on a data unit basis, and each data unit has a predetermined size. 
     
     
       39. A method according to  claim 37 , further comprising the steps of:
   modulating the scrambled data;        obtaining a calculated value of representing a difference between a number of  0  bits and a number of  1  bits included in the modulated scrambled data;        determining whether or not a variation of the calculated value has exceeded a predetermined threshold value;        newly generating further scramble data having a value which is randomly determined;        newly generating a further pseudo - random number sequence in accordance with the value of the newly generated scramble data; and        newly generating further scrambled data by performing the logical operation on the newly generated pseudo - random number sequence and the input data.     
     
     
       40. 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.     
     
     
       41. A method according to  claim 40 , wherein the value of the scramble data is randomly determined on a data unit basis, and each data unit has a predetermined size. 
     
     
       42. A recording medium for recording information thereon,
   wherein scramble data and scrambled data are recorded onto the recording medium,        the scramble data has a value which is randomly determined,        and the scrambled data is obtained by generating a pseudo - random number sequence in accordance with the value of the scramble data and by performing a logical operation on the pseudo - random number sequence and input data.     
     
     
       43. A recording medium according to  claim 41 , wherein the value of the scramble data is randomly determined on a data unit basis, and each data unit has a predetermined size.