JP3338181B2 - Encoding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for encoding digital data used for recording and reproducing digital signals.

[0002]

2. Description of the Related Art Various encoding methods have been proposed for recording digital signals on recording media such as magnetic disks, magnetic tapes and optical disks. As one of the methods,
There is a well-known run-length control encoding method (RLL encoding).

[0003] This RLL encoding is disclosed in Japanese Patent Application Laid-Open No. 52-128024.
(G06F5 / 02), Japanese Patent Application Laid-Open No. 2-119434 (H03M7 / 46) and IEICE Technical Report, Technical Report of IEICE.
It is well known, as shown in MR92-46 (1992.10) Umemoto et al., "Basic study of digital VTR using 8-12 conversion recording code". In particular, (1,7) RLL encoding means that "0" is between adjacent "1" and "1" in an encoded bit string,
At least one and at most seven are always inserted. That is, the encoding is such that “1” does not continue. The conversion rules are well known as shown in FIGS. 1 (a) and 1 (b).

As is well known, the maximum signal inversion interval (T _max ) of the (1,7) RLL coding is 5.33T. Further, the minimum inversion interval (T _min ) is 1.33T, which has good characteristics.
The (1,7) RLL-coded data is recorded, for example, by NRZI modulation.

[0005]

However, as is well known,
Since the (1,7) RLL coding is a variable length code, its error propagation characteristic (EP) is generally worse than that of a fixed length code. The present invention proposes a coding method in which the maximum signal inversion interval (T _max ) and the minimum inversion interval (T _min ) are equal to each other and the error propagation characteristics are better than the conventional (1,7) RLL encoding. Is what you do.

[0006]

SUMMARY OF THE INVENTION The present invention is an encoding method for converting two bits of each data bit of a binary data string into a code composed of three channel bits. 00 ”” 01 ”” 10 ”” 11 ”are A, B,
Assuming that C and D are represented, in principle, A is "010" B
Is converted to "001" C to "100" D to "000", and B
Is followed by BCBC, the first B is converted to "001". Otherwise, when B is followed by CBC, the first B is set to "0".
In other cases, when B is followed by BC, the leading B is converted to "010". In other cases, B
Is followed by C and the last 3 bits of the channel bits converted from the 2 bits before B are 0, the first B is set to “0”
00 ", when C is followed by BCB, the last C is converted to" 100 "; otherwise, B is followed by C, and when BC is followed, the first C is replaced by" 100 ". 000 ”
In other cases, if the last bit of the 3 channel bits converted from the 2 bits before C is 1, C is converted to “000”. In other cases, B follows D or B followed by B. When CC follows, and at least one of the first two bits of the three channel bits converted from the first B or D is 1, the first C is converted to “001”. , B is followed by C, and even if B is A or C or B or D, even if the first two bits of the converted three channel bits are both 0, B
Is converted to “010”, otherwise, when B is followed by C, C is converted to “101”, D is followed by BCBC, and 2 before D When the last 3 bits of the converted channel bits are 0, D is converted to “101”. In other cases, D is followed by BC, and 2 bits before D are converted. When the last bit of the 3 bits is 0, D is converted to “100”; otherwise, D is followed by A or B or D, and 3 channel bits obtained by converting 2 bits before D When the last bit of is 0, D is converted to "101".

Further, the present invention relates to an encoding method for converting 2 bits of each data bit of a binary data string into a code composed of 3 bits of channel bits.
When "00""01""10""11" are respectively expressed as A, B, C, and D, they are converted by the following method: (i) When the current data is A, A is converted to “010.” (ii) When the current data is B and this current B is followed by BCBC, this current B is converted to “001”;
When B is followed by CBC, the current B is converted to “010”. In other cases, when BC is followed by current B, the current B is converted to “010”.
010 "; otherwise, channel bits 3 obtained by converting the current B, followed by C, and converting the two bits before current B.
When the last bit of the bit is 0, the current B is converted to “000”. In other cases, the current B is converted to “001”. (iii) When the current data is C and BCB is followed by current C,
This current C is converted to “100”. In other cases, B is followed by current C, and when BC follows, the current C is converted to “000”. In other cases, the current C is converted to “000”. When the last bit of the three channel bits obtained by converting the previous two bits is 1, the current C is converted to “000”. In other cases, B follows D or B followed by the current C and C followed and the first 2 of the 3 channel bits converted from the first B or D
When at least one of the bits is 1, the current C is set to “001”
In other cases, B is followed by the current C, and even before B is A or C or B or D, the first 3 bits of the converted channel bits When both bits are 0, the current C is converted to “010”; otherwise, when B is followed by the current C, the current C is converted to “010”.
Is converted to “101”. In other cases, the current C
Is converted to “100”. (iv) When the current data is D, the current D is followed by BCBC, and the last three bits of the channel bits obtained by converting the two bits before the current D are 0, the current D is converted to “101”. Otherwise, BC follows current D and 2
When the last bit of the three converted channel bits is 0, the current D is converted to “100”; otherwise, the current D is followed by A or B or D, and the current D is When the last three bits of the channel bits obtained by converting the two bits are 0, the current D is converted to “101”, otherwise, the current D is converted to “000”.

Further, according to the present invention, in each of the above-described encoding methods, when it is detected that a data string in which "1" continues in the converted data string is generated, the converted data string is converted into three.
It is characterized in that it is replaced with another data string in which "1" is not continuous in bit units.

Further, according to the present invention, in each of the above-mentioned encoding methods, when it is detected that a data string in which eight or more “0” s consecutively occurs in the converted data string, the converted data string is converted into three. It is characterized in that it is replaced with another data string in which eight or more “0” are not continuous in bit units.

Further, according to the present invention, in each of the above-described encoding methods, when it is detected that a data string in which "1" continues in the converted data string, the converted data string is converted into three.
When the data string is replaced with another data string in which “1” is not continuous in bit units, and it is detected that a data string in which eight or more “0” s continue occurs in the converted data string, the converted data string is Is replaced with another data sequence in which eight or more “0” s do not continue in units of 3 bits.

[0011]

[0012]

[0013]

[0014]

According to the present invention, in an encoding method for converting each data bit of a binary data string into a code composed of three channel bits, a binary data bit "0" is used.
When 0 ”” 01 ”” 10 ”” 11 ”are represented as A, B, C and D, respectively, in principle, A is“ 010 ”B is“ 001 ”C is“ 10 ”
0 “D” is converted to “000”, and when BCBC follows B, the first B is converted to “001”. In other cases,
When B is followed by CBC, the first B is converted to “010”. In other cases, when B is followed by BC, the first B is changed to “01”.
In other cases, if B is followed by C and the last 3 bits of the channel bits converted from the 2 bits before B are 0, the first B is converted to "000". If B is followed by C, the last C is converted to "100"; otherwise, B is followed by C, and if BC is followed, the first C is converted to "000". In other cases, when the last 3 bits of the channel bits converted from the 2 bits before C are 1, C is converted to “000”. In other cases, B is added after B or D. Followed by CC, and at least one of the first two bits of the three channel bits converted from the first B or D is 1,
The first C is converted to “001”, otherwise, the channel bit is converted even if B is followed by C, and B is A or C or B or D before B When the first two bits of the three bits are both 0, C after B
010 ”, otherwise, if B is followed by C, C is converted to“ 101 ”, D is BC, followed by BCBC, and the channel bits converted from 2 bits before D When the last bit of the 3 bits is 0, D is converted to “101”. In other cases, the last bit of the 3 channel bits obtained by converting the 2 bits before D and BC following D is 3 bits. When 0, D is converted to “100”; otherwise, D is followed by A, B, or D, and the last 3 bits of the channel bits obtained by converting the 2 bits before D are 0. When D
To “101”.

According to the present invention, in an encoding method for converting each two bits of each data bit of a binary data string into a code composed of three channel bits, a data bit "0"
When "0""01""10""11" are represented as A, B, C, and D, respectively, the conversion is performed by the following method: (i) When the current data is A, A is converted to “010.” (ii) When the current data is B and this current B is followed by BCBC, this current B is converted to “001”;
When B is followed by CBC, the current B is converted to “010”. In other cases, when BC is followed by current B, the current B is converted to “010”.
010 "; otherwise, channel bits 3 obtained by converting the current B, followed by C, and converting the two bits before current B.
When the last bit of the bit is 0, the current B is converted to “000”. In other cases, the current B is converted to “001”. (iii) When the current data is C and BCB is followed by current C,
This current C is converted to “100”. In other cases, B is followed by current C, and when BC follows, the current C is converted to “000”. In other cases, the current C is converted to “000”. When the last bit of the three channel bits obtained by converting the previous two bits is 1, the current C is converted to “000”. In other cases, B follows D or B followed by the current C and C followed and the first 2 of the 3 channel bits converted from the first B or D
When at least one of the bits is 1, the current C is set to “001”
In other cases, B is followed by the current C, and even before B is A or C or B or D, the first 3 bits of the converted channel bits When both bits are 0, the current C is converted to “010”; otherwise, when B is followed by the current C, the current C is converted to “010”.
Is converted to “101”. In other cases, the current C
Is converted to “100”. (iv) When the current data is D, the current D is followed by BCBC, and the last three bits of the channel bits obtained by converting the two bits before the current D are 0, the current D is converted to “101”. Otherwise, BC follows current D and 2
When the last bit of the three converted channel bits is 0, the current D is converted to “100”; otherwise, the current D is followed by A or B or D, and the current D is When the last three bits of the channel bits obtained by converting the two bits are 0, the current D is converted to “101”, otherwise, the current D is converted to “000”.

In the present invention, in each of the above encoding methods,
When it is detected that a data string in which "1" s are continuous occurs in the converted data string, the converted data string is replaced with another data string in which "1" s are not continuous in 3-bit units.

In the present invention, in each of the above encoding methods,
When it is detected that a data string in which eight or more “0” s consecutively occur in the converted data string, another data string in which eight or more “0” s do not continue in three-bit units is detected. Replace with

According to the present invention, in each of the above encoding methods,
When it is detected that a data string in which "1" s are continuous occurs in the converted data string, the converted data string is replaced with another data string in which "1" s are not continuous in 3-bit units, and the conversion is performed. When it is detected that a data string in which eight or more “0” s consecutively occur in the subsequent data string, the converted data string is converted into another data string in which eight or more “0” s do not continue in three bits. Perform both processes to perform the replacement process.

[0019]

[0020]

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 3 shows an encoding algorithm showing the features of this embodiment. That is, in this embodiment, the fixed-length conversion of the 2-3 conversion is performed by the algorithm of FIG.

That is, as shown in FIGS. 2 and 3, the two bit data (D0, D1) to be converted are converted into three bit data (M0, M1, M2). In the present invention, two bits of each data bit of a binary data string (the period of which is T) are converted into data composed of three channel bits. Then, this conversion is performed by converting two bit data (D
0, D1), the preceding 6-bit data (DF to DA), the subsequent 8-bit data (D2 to D9), and the converted sign bit (M
A, MB, ME, MF).

The encoded signal is further converted to NRZ
I-modulated and recorded. Therefore, the signal is inverted at "1". At the time of decoding, decoding is performed according to the algorithm of FIG. That is, decoding is performed by referring to a total of 16 bits of three channel data (M0, M1, M2), preceding 7-bit data (MG to MA), and subsequent 6-bit data (M3 to M8). .

The encoding of this embodiment will be described with reference to FIGS. For simplicity, the binary data bits (D0, D1) are “00”, “01”, “10” and “11” respectively.
A, B, C, and D are described below. FIG. 4 shows the principle of encoding by the 2-3 conversion. In FIG. 4, (NRZI)
Is a signal waveform when the converted data is NRZI-modulated.

In this embodiment, as shown in FIG.
In principle, A is converted to “010”. Convert B to “001”. Convert C to “100”. Convert D to "000".
Next, the conversion in a special case (special rule) will be described with reference to FIGS. In the case of A, there are no special rules,
Always converted to "010". Therefore, an example of encoding according to the special rules of B, C, and D will be described. FIG. 5 shows an example of the special rule of B. FIG. 6 shows an example of a special rule of C. FIG. 7 shows an example of the special rule of D. In FIG. 5 to FIG. 7, the data is to be converted. The current 2-bit data (D0, D1) is marked with “*”.

(A) Two bits of data to be converted at the present time
The case where (D0, D1) is A will be described below. In this case, this
A is always converted to “010”. (B) The case where two bits of data to be converted at the moment are B will be described below. As shown in FIG. 5A, when BCBC follows this B (referred to as the current B), the current B is converted to “001”.

As shown in FIG. 5B, when the current B is followed by the CBC, the current B is converted to "010". As shown in FIG. 5C, when BC follows the current B, the current B is converted to “010”. As shown in FIG. 5 (d), when the current B is followed by C, and the last 3 bits of the channel bits converted from the previous 2 bits are 0, the current B
Is converted to "000". Then, the current B other than the above is set to "00
Convert to 1 ”.

(C) The case where the current two bits of data to be converted is C will be described below. As shown in FIG. 6A, when this C (referred to as the current C) follows the BCB, the current C is converted to “100”. As shown in FIG. 6 (b), the current C follows the B, and the BC
Is changed, the current C is converted to “000”.

As shown in FIG. 6C, when the last 3 bits of the channel bits obtained by converting the 2 bits before the current C are 1, the current bit is 1.
Convert C to "000". As shown in FIG. 6 (d), B or D is followed by B, followed by the current C, followed by C, and at least one of the first two bits of the three channel bits obtained by converting the first B or D. When is 1, set the current C to “001”
And convert.

As shown in FIG. 6E, when B is followed by the current C, and before B is A or C, the current C is converted to "010". Also, even if the current C follows B and the preceding B is B or D, if the first two bits of the three converted channel bits are both 0, the current C is ”01
It is converted to “0.” As shown in FIG. 6F, when the current C follows the B, the current C is converted to “101”.

Then, the current C other than the above is converted to "100". (D) The case where the current 2 bits of data to be converted is D will be described below. As shown in FIG. 7 (a), the current D is followed by BCBC and the channel bits 3 obtained by converting the two bits before the current D
When the last bit of the bit is 0, the current D is converted to “101”. As shown in FIG. 7B, when the current D is followed by the BC and the last three bits of the channel bits obtained by converting the two bits before D are 0, the current D is converted to "100".

As shown in FIG. 7 (c), after the current D, A or B or
When D is continued and the last bit of three channel bits obtained by converting the two bits before the current D is 0, the current D is set to “101”.
And convert. Then, the current D other than the above is converted to “000”.

[0033]

According to the present invention, a code having good error propagation characteristics suitable for high-density recording can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a conventional (1,7) RLL conversion.

FIG. 2 is a diagram for explaining the operation of one embodiment of the present invention.

FIG. 3 is a diagram showing an encoding algorithm according to one embodiment of the present invention.

FIG. 4 is a diagram showing an example of encoding according to the basic rule of one embodiment of the present invention.

FIG. 5 is a diagram showing encoding according to a special rule of B in the embodiment.

FIG. 6 is a diagram illustrating encoding according to a special rule of C in the embodiment.

FIG. 7 is a diagram showing encoding according to a special rule of D in the embodiment.

FIG. 8 is a diagram showing a decoding algorithm of this embodiment.

[Explanation of symbols]

 (D0) (D1) 2-bit data, (M0) (M1) (M2) Converted 3-bit data.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshihiro Hori 2-5-1-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-52-128024 (JP, A) JP-A-2-119434 (JP, A) JP-A-4-51615 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03M 5/14 H03M 7/14

Claims (5)

(57) [Claims] 1. Each data bit of a binary data string is 2 bits.
Into a code consisting of three channel bits.
Encoding method, where the binary data bits "00""01""10""11"
When A, B, C, and D are represented, in principle, A is “010”, B is “001”, C is “100”, D is “00”.
If BBC is followed by BCBC, the first B is converted to "001". Otherwise, if B is followed by CBC, the first B is converted.
Is converted to “010”. In other cases, when B is followed by BC, the first B is replaced by “
010 ”; otherwise, B is followed by C and the two bits before B
The last 3 bits of the converted channel bits are 0.
When the first B is converted to “000”, when C follows BCB, the last C is converted to “100”. In other cases, C follows B, and BC follows. Continue
Channel where the first C is converted to “000” and the other two bits before C are converted.
When the last bit of bit 3 is 1, C is changed to “000”.
Conversion, and in other cases, B or C after them followed by B after D
The channel bit that follows C and converts the first B or D
At least one of the first two bits of the three
At this time, the first C is converted to “001”. In other cases, C follows B, and A is before B.
Or converted even if it is C or B or D
The first two bits of the three channel bits are both 0
When, C after B is converted to “010”, otherwise, when C follows B, C is converted to “101”.
The bit that has been converted, the BCBC follows D, and the two bits before D are converted.
When the last bit of the three channel bits is 0, D is set to “10
1 "; otherwise, BC followed by D and two
The last 3 bits of the converted channel bits are 0.
In this case, D is converted to "100". In other cases, D is followed by A or B or D, and
One D previous 2 bits converted channels Bit 3 Bit
When the last bit is 0, D is converted to “101”.
Encoding method, characterized in that that. 2. Each data bit of a binary data string is 2 bits.
Into a code consisting of three channel bits.
The data bits "00", "01", "10", "11" are A,
When expressed as B, C, D, the conversion method is as follows.
The encoding method to be used. (i) If the current data is A, convert this A to “010”
You. (ii) When the current data is B and BCBC follows this current B, this current B is changed to “001”.
And conversion, in other cases, when the CBC is followed current B, the current B
Is converted to “010”. In other cases, when the current B is followed by the BC, the current B
Is converted to “010”. In other cases, the current B is followed by the C and the current B is
The last 3 bits of the converted channel bits
Is 0, the current B is converted to “000”.
Otherwise, convert the current B to “001”. (iii) When the current data is C and the current C follows the BCB, the current C is converted to “100”; otherwise, the current C follows the B, followed by the BC.
At this time, the current C is converted to “000”. In other cases, the channel obtained by converting the two bits before the current C is converted.
When the last bit of the 3 bits is 1, the current C is set to “0”.
00 ”, otherwise B or D followed by B followed by
Channels that follow the current C and C and have converted the first B or D
At least one of the first two bits of the three bits
Is 1, the current C is converted to “001”; otherwise, the current C follows B and the current A before B
Or convert even if it is C or B or D
The first two bits of the three channel bits
If 0, the current C is converted to “010”; otherwise, when B is followed by the current C, the current C is changed to “10”.
In this case, the current C is converted to “100.” (iv) The current data is D, the current D is followed by the BCBC, and the two bits before the current D are converted. Converted
When the last bit of the three channel bits is 0,
Converts current D to "101", otherwise BC follows current D and precedes current D
Channel bits converted from 2 bits 3 bits last bit
Is 0, the current D is converted to “100”; otherwise, the current D is followed by A or B or D,
3 bits of channel bits converted from 2 bits before the current D
When the last bit of the data is 0, the current D is converted to “101”.
And, in the case of other than this, to convert the "000" the current D. 3. A series of "1" s in a converted data string.
When it detects that a data string will occur, it
Another data where "1" is not continuous in 3-bit data string
3. The method according to claim 1 or 2, wherein
Encoding method. 4. The data string after conversion has eight or more "0" s.
When a continuous data sequence is detected,
8 or more consecutive "0" in the converted data string in 3-bit units
Not replace with another data string
Item 3. The encoding method according to item 1 or 2. 5. A series of "1" s in a converted data string.
When it detects that a data string will occur, it
Another data where "1" is not continuous in 3-bit data string
Data that has been replaced by columns and has eight or more consecutive “0” in the converted data column
When it detects that a column occurs, it
Is another data in which 8 or more “0” s are not continuous in 3 bit units.
It is characterized by performing both processes of replacing with the data sequence
3. The encoding method according to claim 1, wherein