KR100752880B1 - Method and apparatus for coding/decoding information - Google Patents

Abstract

The present invention relates to an apparatus and method for information coding in which a DC component is suppressed in the converted data while the data to be converted for recording or transmission has an improved information density. It is divided into three types and coding states belonging to three kinds, and codeword sets belonging to different coding states do not have a common codeword. Under such divided conditions, one m-bit information word is the first, second or third kind of n-bit code if the previous m-bit information word has been converted to an n-bit codeword of the first type. If converted to a word, and the previous m-bit information word is converted to a second type of n-bit codeword, the first or third kind of n-bit codeword is converted, and the previous m-bit information word is converted to a third. If converted to an n-bit codeword of type, it is converted to an n-bit codeword of the first kind. In order to suppress the DC component, the codewords belonging to each coding state are codewords that are parity preserved as long as the number of codewords is allowed. In order to suppress the generation of components, a minimum number of bits is added to a predetermined number of information words and converted into n-bit codewords.

Modulation, DSV, coding, type, type, conversion table, state, coding rate

Description

Method and apparatus for coding / decoding information {Method and apparatus for coding / decoding information}             

1 is a table of Shannon capacity C (d, k) according to k value when d = 2,

2 is an example illustrating how codewords of various subgroups are allocated to various states in an embodiment of the present invention.

3 is an embodiment of a coding apparatus according to the present invention,

4A and 4B show a complete conversion table according to an embodiment for converting a 6-bit information word into an 11-bit codeword,

5 illustrates converting a series of information words into a series of code words using the conversion tables of FIGS. 4A and 4B.

6A and 6B show a complete conversion table in which codewords are newly assigned to each information word so that parity is preserved under the same conditions as those for selecting codewords in the conversion tables of FIGS. 4A and 4B.

7 is a diagram schematically illustrating a process of converting a 1-bit DC component control bit into an 11-bit codeword for every four 6-bit information words.

FIG. 8 shows an embodiment of a coding apparatus using the code conversion table of FIGS. 6A and 6B and inserting a DC component control bit.

9 shows an embodiment of a recording apparatus according to the present invention,

10 illustrates a recording medium and a modulated signal according to the present invention.

11 illustrates a transmission apparatus according to the present invention,

12 illustrates a decoding apparatus according to the present invention,

FIG. 13 illustrates an embodiment of an apparatus for decoding data coded by the coding apparatus of FIG. 8.

14 illustrates a playback apparatus according to the present invention,

15 illustrates a receiving device according to the present invention.

※ Explanation of code for main part of drawing

41: DSV controller 42, 54, 109: buffer memory

50: converter 56: parallel-to-serial converter

58: modulation circuit 100: decoder

102, 104: Look-up Table 108: Bit Eliminator

122: optical pickup (or laser diode) 123: recording control circuit

124 and 224 coding device 125 detection circuit

150: transmitter 160: receiver

200: decoding device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to information coding, and more particularly, to an apparatus and method for information coding with improved information density and suppressing direct current components.

The invention also relates to producing a modulated signal from the coded information, having the record carrier have such coded information, and to the record carrier itself.

The invention also relates to a method and apparatus for decoding a modulated signal and / or coded information from a record carrier.

When data is transmitted through a transmission path or recorded on a recording medium such as a magnetic disk, an optical disk, or a magneto-optical disk, the data is modulated with a code matching the transmission path or recording medium before transmission or recording.

Run length restriction codes, commonly denoted as (d, k) codes, are widely and successfully applied to today's magnetic and optical recording systems, and implement the codes and the codes. The means for doing this are described in detail by KA Schouhamer Immink in a book entitled Codes for Mass Data Storage Systems "(ISBN 90-74249-23-X, 1999).                         

The runlength restriction code is an extension of the initial non return to zero (NRZ) code, where zeros written in binary indicate no (magnetic flux) change in the recording medium, whereas binary 1 ( Ones indicate that the magnetic flux has shifted from one direction to the other in the recording medium.

In the above (d, k) code, in addition to the above-described recording rule, at least '0' must be added between d consecutive data '1' by 'd', and '0' between consecutive data '1'. These k have additional conditions that should not be exceeded. The first condition is for eliminating interference between symbols generated by a group of pulses to be reproduced when a series of '1's are continuously recorded. The second condition is to transition a PLL (Phase Lock Loop) to a reproduction signal. Locking in to recover the clock from the playback data.

If the string of consecutive '0's in which' 1 'is not interleaved is too long, the clock reproduction PLL is out of sync. For example, the code (2,7) should have at least two '0's between the' 1's recorded and no more than seven consecutive '0s' between the '1s' recorded. do.

A series of encoded bit strings is converted into a modulated signal consisting of bit cells having a high or low signal value through modulo-2 intergration, in which the modulated signal Bit '1' represents a change from high to low, or vice versa, and bit '0' represents no change in the modulation signal.

The information transfer efficiency of the code is expressed as the ratio of the number of bits m of the information word to the number n of bits of the code word, that is, m / n. Given the values of d and k, the theoretical maximum code rate that can be obtained is called Shannon capacity. FIG. 1 is a table of Shannon capacities C (d, k) according to k values when d = 2. For the (2,7) code set, as shown in FIG. 1, the Shannon capacity C (2,7) has a value of 0.5174. This means that code rates greater than 0.5174 cannot be achieved when using the (2,7) codeset.

In practice, implementations of code appear to be fractional fractions. The (2,7) codes known so far have a code rate of 1/2. The code rate of 1/2 is only less than the Shannon capacity of 0.5174, so the (2,7) code is a fairly efficient code. In order to achieve a code rate of 1/2, one bit of unqualified data is converted into two bits of conditional bits.

Means for implementing a (2,7) code with an associated code rate 1/2 and associated encoders and decoders are US patents entitled Sequential Encoding and Decoding for Variable Length and Fixed Rate Data Codes. 4,115,768. The patent is patented by inventors 'Eggenberger' and 'Hodges', and publishes an encoder that satisfies runlength constraints imposed by the output sequence.

However, there is a need for even more efficient codes, i.e., codes that can improve the density of the information recorded on the record carrier or transmitted through the transmission path.

When data is transmitted through the transmission line or recorded on the recording medium, the data is modulated into a code sequence suitable for the transmission line or the recording medium before transmission or recording. However, if a DC component is included in the modulated code sequence, various error signals such as a tracking error generated in the servo control of the disk driver may be biased or jitter easily occurs.

Therefore, a signal without direct current component should be used because the first reason is that the recording channels typically do not respond to low frequency components. Suppressing low frequency components in a signal is an optical recording in which the signal is recorded in a track. It works very advantageously when reading signals from the medium, since the continuous tracking control can be prevented from being disturbed by the recording signal.

And, by sufficiently suppressing low frequency components, it is possible to perform improved tracking in which audible noise is reduced. For these various reasons, it is necessary to make a lot of effort to ensure that the modulated sequence does not contain direct current components as much as possible.

As a method for preventing the DC component from being included in the modulated sequence, a DSV (Digital Sum Value) control method has already been proposed. The DSV is the total value obtained by adding the bit string to the bit string, which is the result of NRZI modulation of the channel bit string. It is an indicator representing a component.

If the value for which you are calculating the DSV is virtually constant, it means that the low frequency component is not included in the frequency spectrum of the signal. DSV control is generally not applied to sequences generated by standard (d, k) codes. DSV control for the standard (d, k) code is achieved by calculating the DSV of the encoded bit string after being modulated for a set time and inserting a preset number of DSV control bits into the encoded bit string. At this time, in order to improve the code efficiency, it is preferable to select the number of the DSV control bits as small as possible.

In information recording as well, there is a steady request for reading and increasing the recording speed. However, in order to increase the recording speed, a high servo band width of the tracking mechanism is required, which in turn requires satisfying more stringent restrictions that the low frequency component of the recording signal should be limited.

In addition, the improvement to suppressing low frequency components also has the advantage of reducing the occurrence of audible noise from the tracking mechanism.

Therefore, it is important to ensure that the modulated signal does not contain low frequency components. New code that is developed to improve the density of information is also a challenge to be solved.

It is an object of the present invention that an information word of m-bits is converted into an n-bit codeword at a rate higher than 1/2 so that the same amount of information can be recorded in a smaller space, thereby providing information It is an object of the present invention to provide a method and apparatus for coding / decoding information that allows for improved density.

Another object of the present invention is to convert an information word into an n-bit codeword for improving the density of information, the method of coding / decoding information such that the DC component of the converted codewords is suppressed; It is to provide a device.

In order to achieve the above object, in the present invention, n-bit codewords are divided into three types, and each coding state belonging to three kinds. Under such divided conditions, one m-bit information word is the first, second or third kind of n-bit code if the previous m-bit information word has been converted to an n-bit codeword of the first type. If converted to a word, and if the previous m-bit information word is converted to the n-bit codeword of the second type, it is converted to the first or third kind of n-bit codeword, the previous m-bit information word is the third If converted to an n-bit codeword of type, it is converted to an n-bit codeword of the first kind.

Also, codeword sets belonging to different coding states do not have a common codeword.

In order to suppress the DC component of the n-bit codewords to be converted, codewords belonging to each coding state are codewords that are parity preserved as long as the number of codewords is allowed, and the number of codewords is used. In order to suppress the generation of a DC component due to a codeword in which a parity preservation code cannot be written due to the limitation of C, a minimum number of bits is added to a predetermined number of information words and converted into an n-bit codeword.

In one embodiment according to the invention, the n-bit codeword of the first type ends in 00, the n-bit codeword of the second type ends in 10, and the n-bit codeword of the third type Ends with 01 And the first kind of n-bit codeword starts with 00, the second kind of n-bit codeword starts with 00, 01, or 10, and the third kind of n-bit codeword starts with 00 Or start with 01. Furthermore, in the embodiment according to the present invention, the n-bit codewords satisfy the condition dk, which is (2, k) in which at least two up to k '0's are inserted between consecutive' 1's.

In another embodiment according to the present invention, a coding method and apparatus according to the present invention are employed to record information on a record carrier and to make a record carrier according to the present invention.

In another embodiment according to the invention, a coding method and apparatus according to the invention is adopted for transmitting information.

In the decoding method and apparatus according to the present invention, an n-bit codeword generated by the coding method and apparatus is decoded into an m-bit information word. The decoding has a process of determining the coding state of the next n-bit codeword, and the current n-bit codeword is converted into an m-bit information word based on the state determination.

In another embodiment according to the present invention, the decoding method and apparatus according to the present invention are adapted for reproducing information from a record carrier.

In another embodiment according to the invention, the decoding method and apparatus according to the invention is adapted for receiving information transmitted over a medium.

A general coding method according to the present invention is described from one specific embodiment of this coding method. Next, a general decoding method according to the present invention is described with respect to the embodiment. Various devices according to the invention will also be described next. In particular, the coding apparatus, recording apparatus, transmission apparatus, decoding apparatus, playback apparatus, and receiver apparatus according to the present invention will be described.

Coding Method

According to the present invention, the m-bit information word is converted into an n-bit codeword such that the code rate m / n is larger than 1/2. The codewords are divided into three types: a first type comprising a codeword ending in 00, a second type comprising a codeword ending in 10, and a third type comprising a codeword ending in 01. . Therefore, the codeword of the first type is divided into three subgroups E0000, E1000, and E0100, and the codeword of the second type is divided into three subgroups E0010, E1010, and E0110, and the codeword of the third type. Are divided into three subgroups E0001, E1001, and E0101.

Codeword subgroup E0000 has codewords that start with 00 and end with 00, codeword subgroup E0100 has codewords that start with 01 and end with 00, and codeword subgroup E0010 starts with 00 and ends with 10 With words, codeword subgroup E1010 has codewords starting with 10 and ending with 10, codeword subgroup E0110 has codewords starting with 01 and ending with 10, codeword subgroup E0001 starts with 00 Has a codeword ending in 01, codeword subgroup E1001 has a codeword starting with 10 and ending with 01, and codeword subgroup E0101 has a codeword starting with 01 and ending with 01.                     

The codewords are also divided into at least one first kind of state, at least one second kind of state, and at least one third kind of state. A state belonging to the first kind has only codewords beginning with 00, a second kind of state has codewords beginning with one of 00, 01, and 10, and a third kind of state begins with 00 or 01. Have codewords.

In addition, there is no common codeword between codeword sets belonging to different coding states. In other words, the different states do not contain the same codeword.

Coding method according to an embodiment

In one preferred embodiment of the present invention, the 6-bit information word is converted into an 11-bit codeword. The codeword satisfies the condition of (2, k), and has four (r1) states of the first kind, three (r2) states of the second kind, and two of the third kind ( r3). So the whole has nine states (r = r1 + r2 + r3). To mitigate k-limiting conditions, codewords such as 0000000000000 are prohibited in the conversion table.

To perform encoding, each 11-bit codeword in each state is associated with a coding state direction. The state direction causes a codeword ending in 00 (ie, codewords in subgroups E0000, E1000, and E0100) to be associated with a state direction that points to any one of r (= 9) states, while ending in 10 Codewords (i.e., codewords of subgroups E0010, E1010, and E0110) are assigned to codewords in such a way that they are associated with a state direction indicating one of the first or third types of states. Codewords ending in 01 (ie, codewords of subgroups E0001, E1001, and E0101) are associated with a state direction indicating one of the first kind of states. This is to satisfy the constraint of d = 2.

In addition, as described in detail below, the same codeword may be assigned to different information words within the same state, but may not include the same codeword between different states. In particular, codewords in subgroups E0000, E1000, and E0100 may be assigned nine times to other information words in one state, and codewords in subgroups E0010, E1010, and E0110 may be different information words in one state. Can be assigned six times. In addition, the codewords of the subgroups E0001, E1001, and E0101 may be assigned four times to another information word in one state.

For codewords of the first type, there are 18 codewords in subgroup E0000, 13 in subgroup E1000, and 9 codewords in subgroup E0100, resulting in 360 (= 9 * (18 + 13 + 9)). Combinations of 'codeword-state directions' are generated, and for the second type of codewords, there are nine codewords in subgroup E0010, six in subgroup E1010, and four codewords in subgroup E0110. 6 * (9 + 6 + 4)) combinations of 'codeword-state directions' are generated, and for the third type of codeword, 11 in subgroup E0001, 9 in subgroup E1001, and subgroup E0101. Since there are six codewords, there are 104 (= 4 * (11 + 9 + 6)) combinations of 'codeword-state directions'. Thus, there are a total of 578 (= 360 + 114 + 104) 'codeword-state directions' combinations.                     

For m-bit information words, there are 2 ^m information words. Therefore, 64 (= 2 ⁶ ) information words exist for the 6-bit information word. Since there are nine states in the encoding embodiment, a combination of 576 (= 64x9) 'codeword-state directions' is required, and the combination of the obtained 'codeword-state directions' is 578, so 2 ( = 578-576).

The codewords available in the various subgroups are distributed to each state in the first, second and third kind in accordance with the above constraints. 2 is an example showing how codewords of various subgroups are allocated to various states in this embodiment. As shown in Fig. 2, in this embodiment, states 1, 2, 3, and 4 belong to the first kind, states 5, 6, and 7 belong to the second kind, and states 8 and 9 belong to the third kind. Taking subgroup E0000 with 18 as an example, there are six codes in state 1 and four codewords in state 2, 3 and 4, respectively. In state 1 as an example, in state 1, the number of combinations of 'codeword-state direction' becomes 64 (= 9x6 + 6x1 + 4x1), which means that 6-bit information words can be allocated. do.

Since each codeword of the first type can be assigned to any of nine other states as the state direction, it can be used nine times within one state, and each codeword of the second type is d = Due to the two-person constraint, it can be assigned to one of six states of the first kind and the third kind as the state direction, and thus can be used six times in one state. Further, each codeword of the third type can be assigned to one of the four types of the first kind as the state direction, due to the constraint that d = 2, and therefore can be used four times within a single state.

Any of the r (= 9) coding states shown in FIG. 2 can prove to have a codeword that can be assigned to at least 64 information words that can accommodate 6 bits of information words. In the manner described above, any random series of 6-bit information words can be converted into a unique series of code words corresponding thereto.

4A and 4B show a complete conversion table according to this embodiment for converting a 6 bit information word into an 11 bit codeword. In the conversion tables of FIGS. 4A and 4B, the state direction assigned to each codeword is indicated. In particular, in Figures 4A and 4B, the first column represents the decimal representation of the information word, and the second, fourth, sixth, eightth, tenth, fourteenth, sixteenth, and eighteenth columns represent states 1, 2, 3, and 4. , Codewords (also referred to in the art as 'channel bits') assigned to the information words at 5, 6, 7, 8, and 9. Columns 3, 5, 7, 9, 11, 13, 15, 17, and 19 are the numbers 1, 2, 3, 4, 5, 6, 7, 8, and 9, and the second, 4, 6, The state directions associated with 8, 10, 12, 14, 16, and 18 codewords are shown.

Conversion of a series of information words into a series of codewords will be described further with reference to FIG. 5. The first column of FIG. 5 shows a series of consecutive information words from top to bottom, and the second column shows the decimal values of these information words in parentheses. The third column shows a coding state to be used for the conversion of the information word, which is transmitted when the previous coding word is determined, which is the state direction of the previous code word. The fourth column shows the codewords assigned to the information words according to the conversion tables of FIGS. 4A and 4B, and the fifth column shows the state direction associated with the codewords in the fourth column, which is also the conversion of FIGS. 4A and 4B. It is determined by the table.

The first word from the series of information words shown in the first column of FIG. 5 has a word value of 1 in decimal notation. It is assumed that the coding state when the conversion of a series of information words is started is state 1 (S1). Then, the first word is converted into codeword 00000000100 in accordance with the codeword set of state 1 of the conversion table. At the same time, the next state becomes state 2 (S2). This is because the state direction assigned to the codeword 00000000100 for the decimal number 1 of state 1 is state 2. This means that the next information word (decimal 3) will be converted using the codeword of state 2. As a result, the next information word of decimal 3 is converted into codeword 00001000100. In this way, information words of decimal numbers 5, 12, and 19 are also converted in order.

In the above coding, a preferred embodiment of a method of suppressing and coding a DC component will be described.

In order to suppress the DC component, the codewords selected as shown in FIGS. 4A and 4B are arranged such that corresponding information words and parities are preserved. The parity preservation code was introduced in the invention of International Application No. PCT / IB99 / 00948, and the codeword is assigned to the information word so that the parity between the information word and the code word is the same or opposite.

6A and 6B are conversion tables in which codewords are newly assigned to each information word so as to preserve parity under the same conditions as those for selecting codewords in the conversion tables in FIGS. 4A and 4B. Each codeword in the conversion table has a parity opposite to that of the information word. That is, if the number of one information word is odd, the number of ones of the codewords is even, and if the number of ones of the information words is even, the number of ones of the codewords is odd.

However, the parity of codewords assigned to each state is not divided in half. For example, there are 10 types of codewords assigned to state 1, 00001000100, 00000000100, 00000010010, 00000010000, 00000001001, 00000001000, 00000010001, 00000000010, 00000100001, and 00001000001, of which the code with even parity is 00001000100 , 00000010010, 00000001001, 00000010001, 00000100001, 00001000001, and codes with odd parity are 00000000100, 00000010000, 00000001000, 00000000010. The number of combinations of 'codeword-state directions' that can be used as codewords with even parity is 9 for 00001000100, 6 for 00000010010, 4 for 00000001001, 00000010001, 00000100001, and 00001000001, respectively, and therefore 31 ( = 9 + 6 + 4 x 4). Conversely, the number of combinations of 'codeword-state direction' that can be used as codewords with odd parity is 9 for 00000000100, 00000010000, and 00000001000, 6 for 00000000010, and so 33 (= 3x9 + 6) It becomes a dog.

Since the 6-bit information words have 32 odd parities and even parities, the number of combinations of 'codeword-state directions' that can be allocated to the even parity information words is insufficient. Therefore, in this embodiment in which the parity of the information word and the codeword is opposite to each other, it is impossible to assign the codeword that is parity preserved to one of the information words of the odd parity. An example of codewords not allocated in this way is the information word decimal 61 (= 111101) in FIG. 6B. The parity of this information word is odd, and the parity of the codeword is also assigned 00000010000 which is odd.

In the case of the codeword of state 9, the number of combinations of 'wordword-state direction' of odd parity is 36 as 9x2 + 6x1 + 4x3, while the 'codeword-state direction' of even parity is The number of combinations of 9x2 + 6x1 + 4x1 is 28. Therefore, codewords that are parity preserved are not assigned to information words of four odd parities. In FIG. 6B, the codewords assigned for the information words with decimal values 56, 59, 61, and 62 correspond to this.

The combination of the 'codeword-state direction' colored in the latter conversion table of FIG. 6B is a codeword in which no parity is preserved, that is, the parity of the informationword and the assigned codeword are not opposite. In the embodiment of Figs. 6A and 6B, the number of colored codeword items for which no parity is preserved is a total of 39, which is about 6.8% {= 39 / (64x9)} in the total 'codeword-state direction' combination. This means that the probability that codewords that are parity preserved are allocated to the informationwords is 93.2%. Therefore, in the embodiment of Figs. 6A and 6B, since less than 10% of codewords are not DSV controlled by parity non-preservation, the DSV of the codeword is added by adding control information for DSV control once every 10 information words. Probability can be estimated that control is possible.

In order to make the codewords that cannot be preserved parity as small as described above, when the information word size is m bits, the set of codewords must be 2 ^m or more in each state of the combination of 'codeword-state direction' in each state. Are distributed, but the number of each codeword of odd and even parity multiplied by the number of possible state directions is as even as possible, that is, the number of combinations of 'codeword-state direction' of each parity as close as possible or greater than 2 ^{m −1} . It is preferable to arrange a codeword in each state so that

On the other hand, in the codeword conversion table selected as shown in Figs. 6A and 6B, DC components can be generated when converting an m-bit information word into an n-bit codeword by codewords that are not parity preserved. do. To suppress this, use the following method.

Pre-check P blocks of 1 or more m-bit information words to be converted into n-bit codewords, and insert DC control bits of 1 or more c-bits into the block at the first, middle, or trailing positions. . In this case, the value of the inserted c bit is determined as a value in which the DSV of the bits of the P m-bit information words is constant, for example, 0 is maintained. That is, if c is 1 bit, the control bit is determined to be 0 when the DSV calculated for P information words has a positive value and 1 when the negative value is negative. In this manner, the DC component control bit c slices the bit string inserted for each P m-bit information word block by m-bits, and, for each word of each sliced m-bit, shown in FIGS. 6A and 6B. The conversion table is converted into n-bit codewords.

FIG. 7 schematically illustrates a process of coding information rewards as described above for the case where P is 4, c is 1, m is 6, and n is 11. FIG.

If the unit of the information word to which the DC component control bit is added is set large, that is, if the P value is large, the control bit c may be allocated to two or more bits instead of one bit.

Decoding method

The method of decoding the n-bit codeword (an 11-bit word in this embodiment) received from the recording medium is now described with reference to Figs. 4A and 4B.

For convenience of explanation, it is assumed, for example, that the word values of a series of consecutive codewords received from a recording medium are 00000001000, 00010010000, 10000100100. From the conversion tables of FIGS. 4A and 4B, the first codeword 00000001000 is assigned to the information words 9, 10, 11, 12, 13, 14, 15, 16, and 17, and the corresponding state directions are 1, 2, It can be seen that 3, 4, 5, 6, 7, 8, and 9. The next codeword value is 00010010000, which belongs to the codeword set of state 3. This means that the first codeword 00000001000 was in state direction 3. The first codeword 00000001000 with state direction 3 represents an information word with decimal number 11. Therefore, the first codeword 00000001000 is determined to represent the information word having decimal number 11.

And, the third codeword 10000100100 is an element of state 6. Thus, in the same manner as above, the second codeword 00010010000 is determined to represent the information word having the decimal number 14. In this way other codewords can be decoded. Note that in order to convert the current codeword into a unique information word, the current codeword and the next codeword must be identified.

On the other hand, when the parity preservation code conversion table of FIGS. 6A and 6B is used to suppress the DC component in the coding process, a pure information word should be output by removing the inserted bit c for DC component suppression. Thus, when (P + 1) codewords are first decoded and converted into (P + 1) informationwords, c bits, e.g., one bit, at a given position are removed, and then P m-bit informationwords are removed. Are sequentially output, and the remaining (m-1) bits sequentially constitute the {Pxm + (m-1)} bits when the next P information words are obtained. Then, one bit at a predetermined position is removed from the bit block of (Pxm + 1) from the beginning, and are sequentially output as P m-bit information words. The remaining (m-2) bits are output as m-bit information words in the above manner once the next decoded word is obtained. In this way, a pure information word can be obtained from the codeword coded using the conversion table of FIGS. 6A and 6B and the c-bit DC component control bit.

The process of converting from the conversion tables of Figs. 6A and 6B to the information word into which the c-bit DC component control bits are inserted is exactly the same as the method described above with reference to the conversion tables of Figs. 4A and 4B.

Coding Device

3 shows an embodiment for the coding device 124 according to the present invention. The coding device 124 converts the m-bit information word into an n-bit codeword. Here, the number of different coding states r is represented by s bits. For example, when the number of coding states r is 9, s becomes 4. As shown, the coding device 124 includes a converter 50 for converting the binary input signal of (m + s) into a binary output signal of (n + s). In a preferred embodiment, the converter 50 addresses the conversion table based on a read-only memory (ROM) storing a conversion table according to at least one embodiment of the invention and an m + s binary input signal. an address circuit for addressing). However, instead of read-only memory, the converter 50 may comprise a combinational logic that allows to achieve the same results as in the conversion table according to at least one embodiment of the invention.

At the input of the converter 50, the m input is connected to a first bus 51 for receiving an m-bit input word, and at the output of the converter 50, the n output carries n-bit codewords. It is connected to the second bus 52 for. The s input is then connected to a third bus 53 for receiving a status word indicating the instantaneous coding state. The status word is transferred from a buffer memory 54 which contains, for example, s flip-flops. The buffer memory 54 has s inputs connected to a fourth bus 55 for receiving a state direction to be loaded into itself as a state word. The s output of the transducer 50 is used to convey the state direction to be loaded into the buffer memory 54.

The second bus 52 is connected to the parallel input terminal of the parallel-to-serial converter 56. The parallel-to-serial converter 56 converts the codeword received through the second bus 52 into a serial bit string. The signal line 57 applies the serial bit string to the modulation circuit 58. The modulation circuit 58 converts the bit string into a modulation signal. The modulated signal is transmitted through the signal line 60. The modulation circuit 58 may be any known circuit, such as a modula-2 integrator, which converts binary data into a modulation signal.

For the purpose of synchronizing the operation of the coding device, the coding device generates, for example, a clock signal for controlling the timing of the parallel-to-serial converter 58 and the loading of the buffer memory 54. A conventional type of clock generator (not shown).

In operation, the converter 50 receives an m-bit information word and an s-bit status word from the first bus 51 and the third bus 53, respectively. The s-bit state word indicates a state in a conversion table used when converting an m-bit information word. Thus, based on the value of the m-bit information word, the n-bit codeword is determined from the codeword in the state identified by the s-bit statusword.

In addition, the state direction associated with the n-bit codeword is also determined. The state direction, ie its value, is converted to an s-bit binary word. Alternatively, the state direction is stored as an s-bit binary word in the conversion table. The converter 50 outputs the n-bit codeword to the second bus 52 and the s-bit state direction to the fourth bus 55, respectively. The buffer memory 54 stores the s-bit state direction as a state word, and receives the s-bit state word through the third bus 53 to receive the next m-bit information word of the converter 50. It is applied to the converter 50 in synchronization with the time point. As described above, this time synchronization is performed based on a clock signal of one of the well-known methods.                     

The n-bit codeword on the second bus 52 is converted into serial data by the parallel-to-serial converter 56, and the converted serial data is converted into a modulated signal by the modulator 58. The modulated signal undergoes subsequent processing for recording or transmission.

FIG. 8 illustrates a coding apparatus 224 for inserting c-bit DC component control bits using the code conversion table of FIGS. 6A and 6B to suppress the DC component of the codeword. As shown, the coding device 224 includes the coding device 124 of FIG. Then, before applying the information word to the coding device 124, the DSV is calculated by inputting the m-bit information word into P units, and the DSV inserts c-bit, for example, 1-bit DC component control bits. Controller 41. In addition, a buffer memory 42 for temporarily storing DS information for the input information words is calculated for P and sequentially transferred to the coding apparatus of FIG. 3.

The DSV controller 41 sequentially stores the information word in the buffer memory 42 when the information word is input. When the number of information words to be stored becomes P, the DSVs are calculated to determine the value of the one-bit DC component control bit for the DSV to be a constant value and inserted into the head, middle or tail of the P information words. Then, the m-bits are sliced into intermediate words, and then loaded on the first bus 51 of the coding apparatus 124 and transferred to the converter 50 in order.

Since the bit to be output is (Pxm + c) when the input data is Pxm bits, the DSV controller 41 must provide the data to the converter 50 at a clock rate as fast as this ratio. Initially, while waiting for the next P information words to be completed for DSV calculation of the next P information words, the first P intermediate words (words in which the control bit c is inserted) are transferred to underrun ( It is preferable to start the transmission of the intermediate word to the converter 50 after reception of at least 2P information words so that no underrun occurs.

Instead of checking the DC components of the P m-bit information words as described above, the DC components of the (Pxm-c) bit strings are examined and the control bits are added to c bits to form Pxm bits, and then the converter It is also possible to apply P m-bit intermediate words in m-bit order to (50).

The converter 50 converts the applied m-bit intermediate words into codewords in the same manner as described above using the conversion tables of FIGS. 6A and 6B.

Recorder

9 shows a recording apparatus for recording information, including the coding apparatus 124 or 224 of FIG. 3 or 8 according to the present invention.

As shown in FIG. 9, m-bit information is converted into a modulated signal through the coding device 124 or 224. The modulated signal generated by the coding device 124 or 224 is transferred to the write control circuit 123. The write control circuit 123 controls the optical pickup or the laser diode 122 according to a modulation signal applied to the optical pickup or laser diode 122 so that a mark pattern corresponding to the modulation signal can be engraved on the recording medium 110. Any of the general control circuits is possible.

10 shows by way of example a record carrier 110 according to the invention. The recording medium 110 shown is an optical disc of a read-only type. However, the recording medium 110 according to the present invention is not limited to the read-only type optical disc, and may be any type of optical disc such as a write once optical disc, a rewritable optical disc, or the like. Further, the recording medium 110 is not limited to an optical disc, but may be any type of recording medium such as a magnetic disc, a magneto-optical disc, a memory card, a magnetic tape, or the like.

As shown in FIG. 10, the recording medium 110 according to an embodiment of the present invention includes an information pattern arranged on the track 111. In particular, FIG. 10 shows the track 111 enlarged along one direction 114 of the track 111. As shown, the track 111 includes a pit region 112 and a non-pit region 113. In general, the pit and non-pit regions 112 and 113 represent a constant signal interval (0 in a codeword) of the modulation signal 115, and the transition between the pit and non-pit regions is a change in the logic state in the modulation signal 115. (1 in the codeword).

As described above, the recording medium 110 may be obtained by first generating a modulated signal and then recording the modulated signal. Alternatively, if the recording medium is an optical disc, the recording medium 110 may also be made by known mastering and copying techniques.

Transmission

11 illustrates a transmission apparatus for transmitting information, including the coding apparatus 124 or 224 of FIG. 3 or 8 according to the present invention. As shown in Fig. 11, the m-bit information word is converted into a modulated signal by the coding device 124 or 224. The transmitter 150 performs the necessary processing to convert the modulated signal into a form for transmission depending on the communication system to which it belongs, and then converts the converted modulated signal into air (or space) or optical fiber. It transmits through communication media such as cable, conductor and so on.

Decoding device

12 illustrates a decoder according to the present invention. The decoder 100 performs a reverse process of the converter 50 of FIG. 3 and converts an n-bit codeword into an m-bit information word according to the present invention.

As shown, the decoder 100 has a first lookup table (LUT) 102 and a second searcher 104. The first and second searchers 102 and 104 store conversion tables used to generate n-bit codewords to be decoded. In the figure, K represents time, and the first searcher 102 receives the (K + 1) th n-bit codeword, and at the same time, the second searcher 104 performs the first searcher 102. Receive the output of and the K th codeword. Thus, the decoder 100 acts like a sliding block decoder. At every block time instant, the decoder 100 decodes one n-bit codeword into one m-bit information word and is called the next n-bit codeword (also called a 'channel bit stream') of serial data. Proceed to).                     

In operation, the first searcher 102 determines the state of the (K + 1) th codeword from the stored conversion table and outputs the determined state to the second searcher 104. The output of the first searcher 102 is a binary number with a range of change from 1 to r (r is the number of states in the conversion table). The second retriever 104 determines the possible m-bit information word associated with the K th codeword, using the stored conversion table, and then the possible m-bits represented by the n-bit codeword. A particular one of the information words is selected using the state information from the first searcher 102 and the stored conversion table.

Just for supplementary explanation, assume that the n-bit codeword is an 11-bit codeword made using the conversion table of FIGS. 4A and 4B. Referring to Fig. 5, if the (K + 1) th 11-bit codeword is 00001000100, the first searcher 102 determines the state of the codeword as state2. In addition, if the K-th 11-bit codeword is 00000000100, the second searcher 104 determines that the K-th 11-bit codeword is a decimal 0, 1, 2, 3, 4, 5, 6, 7, or 8 value. It is determined that it represents one of the 6-bit information word having a. And, since the next state or state direction of state 2 is applied from the first finder 102, the second finder 104 has an 11 bit codeword 00000000100 associated with state 2 indicates the value of decimal one. Based on pointing to a bit information word, it is determined that the K-th 11-bit codeword is a 6-bit information word representing the value of decimal one.

Fig. 13 is a decoding for decoding the data coded by the coding device 224 using the code conversion table of Figs. 6A and 6B and inserting c-bit DC component control bits to suppress the DC component of the codeword. The apparatus 200 is illustrated.

As shown, the decoding apparatus 200 includes the decoder 100 of FIG. 12. The decoder 100 in the apparatus 200 converts the input codewords into intermediate words (words in which a c-bit DC component control bit is inserted) using the conversion tables of FIGS. 6A and 6B. In addition, the decoding apparatus 200 checks the buffer memory 109 for temporarily storing the intermediate words output from the decoder 100 and the intermediate words temporarily stored in the buffer memory 109. If the bit block is larger than the predetermined (Pxm + c), the c bit of the predetermined position, the beginning, the middle, or the tail of the bit string of (Pxm + c) is removed from the front, and the (Pxm) bit string is stored in the buffer. And a bit remover 108 for reading out from the memory 109 and sequentially outputting the output bus 106 in units of bits. Even during the output operation of the bit remover 108, intermediate words output by the decoder 100 are continuously stored after the previously stored bits.

After outputting the (Pxm) bits, when the bits of the residual data stored in the buffer memory 109 and the data added by the decoding operation become (Pxm + c) again, the control bits of the c bit at the predetermined position By removing the output to the output bus 106 in order.

Instead of removing the control bits for the bits of (Pxm + c) as described above, when the bit stored in the buffer memory 109 becomes (Pxm), the double c bits are removed and (P-1) m-bits. The bit removing operation of outputting the information word may be performed. This depends entirely on the number of bits of the information word in which the coding device 224 described above inserts the c-bit DC component control bits.

Playback device

14 illustrates a playback device including the decoder 100 of FIG. 12 or the decoding device 200 of FIG. 13 according to the present invention. As shown, the reproducing apparatus includes an optical pickup 122 of a known type that reads the recording medium 110 according to the present invention. The record carrier 110 may be any type of record carrier as discussed above.

The optical pickup 122 generates an analog read signal modulated according to an information pattern on the recording medium 110. The detection circuit 125 converts the read signal into a binary signal in a form that can be received by the decoder 100 or the decoding apparatus 200 according to a conventional method. The decoder 100 or the decoding apparatus 200 decodes the binary signal to obtain an m-bit information word.

Receiver

15 illustrates a receiving apparatus including the decoder 100 of FIG. 12 or the decoding apparatus 200 of FIG. 13 according to the present invention. As shown, the receiver includes a receiver 160 for receiving a signal transmitted through a medium such as air (or space), an optical fiber, a cable, a conductor, or the like. The receiver 160 converts the received signal into a binary signal in a form that the decoder 100 can accommodate. The decoder 100 or the decoding apparatus 200 decodes the binary signal to obtain an m-bit information word.

The above-described method and apparatus for coding / decoding information according to the present invention suppresses the DC component of the coded data to be recorded or transmitted while at the same time making the recording medium or the transmitted data have an improved information density. Therefore, there is an advantage that the capacity of the recording medium can be increased and the information transmission speed is relatively high. Moreover, due to the DC component suppression, an error occurrence rate can be significantly lowered when the recorded or received code is restored.

The present invention has been described in detail with particular reference to preferred embodiments thereof. However, modifications and variations may be effected within the spirit and scope of the present invention.

Claims (39)

Receiving data; Inserting a control bit of c-bit which calculates a DC component value for the Q bits of the received data and makes the value small in an absolute sense; And Converting the control bit-inserted data into an n-bit (n is an integer greater than m) codeword in m-bit (m is integer) information word units. The n-bit codewords are divided into three types and coding states belonging to three kinds, and sets of codewords belonging to different coding states do not include any common codewords. A large number of codewords belonging to a coding state are assigned to each m-bit information word so that each possible value and parity of the m-bit information word is preserved, and one m-bit information word is assigned to the previous m- If the bit information word is converted into an n-bit codeword of the first type, it is converted into an n-bit codeword of the first, second or third kind, and the previous m-bit information word is n-bit of the second type. If converted to a codeword, converts to a first or third kind of n-bit codeword, and if the previous m-bit information word is converted to a third type of n-bit codeword, then the first kind of n-bit code Conversion room characterized by converting into words . The method of claim 1, wherein the converting step converts the m-bit information word into an n-bit codeword that satisfies a dk constraint, wherein d is a minimum of one consecutive one in the n-bit codeword. A number of zeros, wherein k is a maximum number of zeros between consecutive ones in said n-bit codeword. 3. The r-bit codeword of claim 2, wherein the n-bit codeword is divided into r1 coding states of the first type, r3 coding states of the second type, and r3 coding states of the third type, respectively. , r2, and r3 are integers greater than or equal to 1, and each of the r1, r2, and r3 coding states is an n-bit code different from the n-bit codewords in other r1, r2, and r3 coding states. And a word. The conversion method according to claim 3, wherein m / n is larger than 1/2, d = 2, and r1 + r2 + r3 = 9. 4. The n-bit method according to claim 3, wherein for any n-bit codeword, the case of the next coding state and the number of combinations of the n-bit codewords must be 2 ^m or more for each coding state. Distribute a set of codewords, and in the next coding state, codewords are arranged in each coding state such that the number of odd parity multiplied by the number and the number of codewords of even parity is as close to or greater than 2 ^{m < -1} > Conversion method. The conversion method according to claim 1, wherein Q is P x m (P is an integer of 1 or more) and c is 1. The conversion method according to claim 1, wherein Q = P x m1 (P is an integer of 1 or more), and c is 1. 2. The method of claim 1, wherein the n-bit codeword of the first type ends in 00, the n-bit codeword of the second type ends in 10, and the n-bit codeword of the third type Ending in 01, the n-bit codeword in the coding state within the first kind starts with 00, and the n-bit codeword in the second kind of coding state starts with 00, 01 or 10, and And the n-bit codeword in the third type of coding state begins with 00 or 01. The method of claim 1, wherein m is 6 and n is 11. The conversion method according to claim 1, further comprising generating a modulated signal from the n-bit codeword and recording the result on a recording medium. The method of claim 1, further comprising generating and transmitting a modulated signal from the n-bit codeword. A controller that receives the data and calculates a direct current component value for the Q bits of the received data and inserts a c-bit control bit that makes the value small in an absolute sense; And And a converter for converting the control bit-inserted data into an n-bit (n is an integer greater than m) codeword in m-bit (m is integer) information word units. The n-bit codewords are divided into three types and coding states belonging to three kinds, and sets of codewords belonging to different coding states do not include any common codewords. A large number of codewords belonging to a coding state are assigned to each m-bit information word so that each possible value and parity of the m-bit information word is preserved, and one m-bit information word is assigned to the previous m- If the bit information word is converted into an n-bit codeword of the first type, it is converted into an n-bit codeword of the first, second or third kind, and the previous m-bit information word is n-bit of the second type. If converted to a codeword, converts to a first or third kind of n-bit codeword, and if the previous m-bit information word is converted to a third type of n-bit codeword, then the first kind of n-bit code Coding length, characterized by converting to a word . The coding apparatus according to claim 12, wherein the converter receives a coding state together with each m-bit information word and converts the m-bit information word into the n-bit codeword based on the coding state. . 14. The apparatus of claim 13, further comprising a buffer for supplying said coding state to said transformer, said transformer determining a coding state for a next m-bit information word as part of said conversion process. And storing in the buffer. 15. The coding apparatus according to claim 14, further comprising a modulator for generating a modulated signal from said n-bit codeword, and recording means for recording said modulated signal on a recording medium. 13. The coding apparatus of claim 12, further comprising a modulator for generating a modulated signal from the n-bit codeword and a transmitter for transmitting the modulated signal. The coding apparatus according to claim 12, wherein Q is P x m (P is an integer of 1 or more), and c is 1. 13. The coding apparatus according to claim 12, wherein Q is P x m-1 (P is an integer of 1 or more) and c is 1. Receiving at least one n-bit (n is integer) codeword; Converting an m-bit (m is an integer less than n) information word for each n-bit codeword received; And And removing the c bit at a predetermined position from Q + c (Q + c is m or more and Q and c are Q> c integers) bits in the converted one or more information words. Understand, If one m-bit information word has been converted from a previous m-bit information word to an n-bit codeword of the first type, the first, second or third kind of n-bit codeword In other words, if the previous m-bit information word has been converted to the n-bit codeword of the second type, the first or third kind of n-bit codeword, and the previous m-bit information word is the n-bit of the third type. If converted into a codeword, the n-bit codeword is divided into three types and coding states belonging to three kinds, and codewords belonging to different coding states so as to be converted into a first kind of n-bit codewords. The set does not contain any common codewords, and many of the codewords belonging to each coding state are such that each possible value and parity of the m-bit information word is assigned to each m-bit information word to be preserved. A decoding method characterized by the above. 20. The apparatus of claim 19, wherein the n-bit codeword is divided into r1 coding states of the first kind, r3 coding states of the second kind, and r3 coding states of the third kind, , r2, and r3 are integers greater than or equal to 1, and each of the r1, r2, and r3 coding states is n-bit different from the n-bit codewords in other r1, r2, and r3 coding states. And a codeword. 21. The method of claim 20, wherein the converting step determines which of the r1, r2, and r3 states the next n-bit codeword belongs to, and based on the determined coding state, determines the current n-bit codeword. A decoding method characterized by converting the m-bit information word. 22. The method of claim 21, wherein at least one of the r1, r2, and r3 coding states comprises one or more identical n-bit codewords, each of the same n-bit codewords having a different associated state direction; And each state direction is one of the following states of the r1, r2, and r3 coding states to obtain a next n-bit codeword when the m-bit information word is converted into the n-bit codeword. Decoding method characterized in that. 23. The method of claim 22, wherein the n-bit codeword meets a dk constraint, wherein d is a minimum number of zeros between consecutive ones in the n-bit codeword, and k is within the n-bit codeword. A maximum number of zeros between consecutive ones. 24. The decoding method according to claim 23, wherein m / n is greater than 1/2, d = 2, and r1 + r2 + r3 = 9. 23. The method of claim 22, wherein the set of n-bit codewords is distributed such that the number of combinations of n-bit codewords and each state direction is necessarily 2 ^m or more for each coding state, but the number of the following coding states And a codeword arranged in each coding state such that the number of each codeword of the multiplied odd parity and the even parity is as close to or greater than 2 ^{m < -1 &gt}; 20. The method of claim 19, wherein the n-bit codeword of the first type ends in 00, the n-bit codeword of the second type ends in 10, and the n-bit codeword of the third type Ends with 01, and the n-bit codeword in the coding state within the first kind begins with 00, and the n-bit codeword in the second kind of coding state begins with 00, 01 or 10. And the n-bit codeword in the third type of coding state begins with 00 or 01. 20. The method of claim 19 further comprising receiving a modulated signal and demodulating the modulated signal into at least the n-bit codeword. 20. The method of claim 19, further comprising: reproducing a modulated signal from a recording medium; And demodulating the modulated signal into at least the n-bit codeword. 20. The method of claim 19, wherein c is one. A converter that receives one or more n-bit (n is integer) codewords and converts each received m-bit codeword into an m-bit (m is an integer less than n) information word; And And a bit remover for removing c bits at a predetermined position from Q + c (Q + c is an integer greater than m and Q and c are Q> c) bits in the converted one or more information words. , The n-bit codeword may be a first, second or third type if one m-bit information word has been converted to a first type of n-bit codeword. kind) n-bit codeword, if the previous m-bit information word has been converted to the second type of n-bit codeword, then the first or third kind of n-bit codeword, the previous m-bit information word If is converted to the n-bit codeword of the third type, the codeword is divided into three types and coding states belonging to the three types so as to be converted to the first type of n-bit codewords. The set does not contain any common codewords, and a number of codewords belonging to each coding state are assigned to each m-bit information word so that each possible value and parity of the m-bit information word is preserved. Decoding apparatus characterized in that. 31. The r-bit codeword of claim 30, wherein the n-bit codeword is divided into r1 coding states of the first type, r3 coding states of the second type, and r3 coding states of the third type. , r2, and r3 are integers greater than or equal to 1, and each of the r1, r2, and r3 coding states is an n-bit code different from the n-bit codewords in other r1, r2, and r3 coding states. And a word decoding device. 32. The apparatus of claim 31, wherein the transformer determines which of the states r1, r2, and r3 belongs to the next n-bit codeword, and m based on the determined coding state. -Decoding device, characterized by converting into a bit information word. 33. The method of claim 32, wherein at least one of the r1, r2, and r3 coding states comprises one or more identical n-bit codewords, each of the same n-bit codewords having a different associated state direction; And each state direction is one of the following states of the r1, r2, and r3 coding states to obtain a next n-bit codeword when the m-bit information word is converted into the n-bit codeword. Decoding apparatus characterized by pointing to. 34. The method of claim 33, wherein the n-bit codeword satisfies a dk constraint, wherein d is a minimum number of zeros between consecutive ones in the n-bit codeword, and k is within the n-bit codeword. And a maximum number of zeros between consecutive ones. 35. The decoding apparatus of claim 34, wherein m / n is greater than 1/2, d = 2, and r1 + r2 + r3 = 9. 31. The method of claim 30, wherein the n-bit codeword of the first type ends in 00, the n-bit codeword of the second type ends in 10, and the n-bit codeword of the third type Ends with 01, and the n-bit codeword in the coding state within the first kind begins with 00, and the n-bit codeword in the second kind of coding state begins with 00, 01 or 10. And the n-bit codeword in the third type of coding state begins with 00 or 01. 31. The decoding apparatus according to claim 30, further comprising a demodulator for receiving a modulated signal and demodulating the modulated signal into at least the n-bit codeword. 31. The decoding apparatus according to claim 30, further comprising reproducing means for reproducing a modulated signal from a recording medium and demodulating the modulated signal into at least the n-bit codeword. 31. The decoding apparatus of claim 30, wherein c is one.

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