KR100470026B1 - 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 two types, and coding states belonging to two 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 converted into a first or second kind of n-bit codeword if the previous m-bit information word is converted into an n-bit codeword of the first type. If the previous m-bit information word has been converted to the n-bit codeword of the second type, it is converted to the first kind of n-bit codeword. In the inverse transformation process, an n-bit codeword is decoded into an m-bit information word by using a conversion table. In forming the conversion table, the n-bit codeword is converted into a coding state and a next coding state. By grouping the same things together, the amount of memory needed for the conversion table is reduced.

Description

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

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, i.e., m / n. Given this, 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 = 1. For the (1,7) code set, as shown in FIG. 1, the Shannon capacity C (1,7) has a value of 0.67929. This means that code rates greater than 0.67929 cannot be achieved when using the (1,7) codeset.

In practice, implementations of code appear to be fractional fractions. The (1,7) codes known so far have a code rate of 2/3. The code rate of 2/3 is only slightly smaller than the Shannon capacity of 0.67929, so the (1,7) code is a fairly efficient code. In order to achieve a code rate of 2/3, two bits of unqualified data are converted into three bits of conditional bits.

Means for implementing a (1,7) code having a code rate of 2/3 and associated encoders and decoders, for generating a noise free sliding block code for a (1,7) channel at a code rate of 2/3, and US Patent No. 4,413, 251 entitled Method and Apparatus for Generating A Noiseless Sliding Block Code for a (1,7) Channel with Rate 2/3. This patent is patented by 'Adler' and the like and discloses an encoder which is a finite-state machine having five internal states.

4,488,142, entitled Apparatus for Encoding Unconstrained Data onto a (1,7) Format with Rate 2/3, for encoding condition-nonconforming data in (1,7) format. The patent, patented by 'Franaszek' as inventor, discloses an encoder with eight internal states.

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

It is an object of the present invention that the information word of m-bits is converted into codewords of n-bits at a rate higher than 2/3 so that the same amount of information can be recorded in a smaller space, thereby providing information Allow the density to improve.

It is still another object of the present invention to reduce the size of the conversion table necessary for decoding an n-bit codeword into an m-bit information word.

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

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 to 4H show a complete conversion table according to an embodiment for converting a 9-bit information word into a 13-bit codeword.

FIG. 5 illustrates conversion of a series of information words into a series of code words using the conversion table of FIGS. 4A to 4H.

6 illustrates a structure of a conversion table for coding an information word,

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

8 illustrates a recording medium and a modulated signal according to the present invention;

9 illustrates a transmission apparatus according to the present invention,

10 illustrates a decoding apparatus according to the present invention,

11A and 11B illustrate the structure of a lookup table for obtaining coding state values from coding words, respectively.

12A and 12B illustrate the structure of a conversion table for converting a coding word into an information word, respectively.

13 illustrates a playback apparatus according to the present invention,

14 illustrates a receiving device according to the present invention.

※ Explanation of code for main part of drawing

54, 109: Buffer Memory 50: Converter

56: parallel-to-serial converter 58: modulation circuit

100: decoder

102, 104: Lookup Table

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

124: coding apparatus 125: detection circuit

150: transmitter 160: receiver

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

In the conversion table to be used for decoding, n-bit codewords are grouped with codewords having the same coding state, and also coded groups with the same coding state with which the next n-bit codeword is to be selected are used. Writing of the coding state for each n-bit codeword is unnecessary and thus saves space in the memory.

In one embodiment according to the present invention, the n-bit codeword of the first type ends in 0, the n-bit codeword of the second type ends in 1, and the first kind of n− Bit codewords begin with zero, and the second kind of n-bit codewords begin with zero, or one. Furthermore, in the embodiment according to the present invention, the n-bit codewords satisfy the condition dk of (1, k) in which at least one and 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 are adapted for receiving information transmitted via 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 greater than 2/3. The codewords are divided into two types, a first type including a codeword ending in zero and a second type including a codeword ending in one. Accordingly, the first type codeword is divided into two subgroups E00 and E10, and the second type codeword is divided into two subgroups E01 and E11.

Codeword subgroup E00 has codewords starting with 0 and ending with 0, codeword subgroup E01 has codewords starting with 0 and ending with 1, and codeword subgroup E10 starts with 1 and ends with 0 With words, codeword subgroup E11 has codewords that start with 1 and end with 1.

The codewords are also divided into at least one first kind of state and at least one second kind of state. A state belonging to the first kind has only codewords beginning with zero, and a second kind of state has codewords beginning with zero or one.

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 9-bit information word is converted into a 13-bit codeword. The codeword satisfies the condition of (1, k), and is divided into three states of the first kind and two states of the second kind. So the whole has five states. To mitigate k-limiting conditions, codewords such as 0000000000000, 0000000000001, and 0000000000010 are prohibited in the conversion table. When the codewords are distributed, there are 231 in the subgroup E00, 144 in the subgroup E10, 143 in the subgroup E01, and 89 codewords in the subgroup E11.

To perform encoding, each 13-bit codeword in each state is associated with a coding 'state direction'. 'State direction' indicates the next state to select a codeword in the encoding process. The state direction causes a codeword ending in zero (i.e., codewords in subgroups E00 and E10) to be associated with a state direction pointing to any one of r (= 5) states, while a codeword ending in 1 ( In other words, the codewords of the subgroups E01 and E11) are assigned to the codeword in such a way as to be associated with the state direction indicating one of the first kind of states. This is to satisfy the condition that d = 1, i.e., the codeword following the codeword ending in 1 must start with 0.

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 E10 and E00 may be assigned five times to other information words in one state, and codewords in subgroups E01 and E11 may be assigned three times to other information words in one state. Can be

For the first type of codeword, there are 231 codewords in subgroup E00 and 144 codewords in subgroup E10. Therefore, 1875 (= 5 * (231 + 144)) codeword-state directions There are 143 combinations of codewords of the second type, and there are 143 codewords in subgroup E01 and 89 codewords in subgroup E11, so there are 696 (= 3 * (143 + 89)) codeword-state directions. A combination of Thus, there are a total of 2571 (= 1875 + 696) 'codeword-state directions' combinations.

For m-bit information words, there are 2 ^m information words. Therefore, for the 9-bit information word, there are 512 (= 2 ⁹ ) information words. Since there are five states in the encoding embodiment, a combination of 2560 (= 512x5) 'codeword-state directions' is required, and the combination of the obtained 'codeword-state directions' is 2571 and thus 11 ( There are two margins.

The codewords available in the various subgroups are distributed to each state in the first and second kind to meet 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, and 3 belong to the first kind, and states 4 and 5 belong to the second kind. For example, with 230 subgroups E00, there are 76 codewords in states 1, 2, and 3, and 1 codeword in states 4 and 5, respectively. In the state 1 as an example, the number of combinations of 'codeword-state direction' is 512 (= 5x76 + 3x44), which means that an information word of 6 bits can be allocated.

Each codeword of the first type can be used five times in one state, since the state direction can be assigned to any of five different states, and each codeword of the second type is d = Because of the constraint of 1, it can be assigned to only one of three states of the first kind as the state direction, and thus can be used three times within one state.

Of the r (= 5) coding states shown in FIG. 2, it can be proved that any one has a codeword that can be assigned to at least 512 information words that can accommodate an information word of 9 bits. In the manner described above, any random series of 9-bit information words can be converted into a unique series of code words corresponding thereto.

4A-4H show a complete conversion table according to this embodiment for converting a 9 bit information word into a 13 bit codeword. In the conversion table of FIGS. 4A to 4H, the state direction assigned to each codeword is indicated. In particular, in FIGS. 4A-4H, the first column represents the decimal representation of the information word in the second column, and the third, fifth, seventh, nineth and eleventh columns represent states 1, 2, 3, 4, and 5 Denotes a codeword (also referred to as 'channel bit' in the art) assigned to an information word. Columns 4, 6, 8, 10, and 12 are the numbers 1, 2, 3, 4, and 5, respectively, indicating the state directions associated with the codewords in columns 3, 5, 7, 9, and 11, respectively. have.

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 9-bit 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 table of Figs. 4A to 4B, and the fifth column shows the state direction associated with the codewords of the fourth column, which is also the conversion table of Figs. 4A to 4B. Is determined by.

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 0000000000100 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 0000000000100 for the decimal number 1 of the state 1 is the 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 0001010001010. In this way, information words of decimal numbers 5, 12, and 19 are also converted in order.

The method of decoding the n-bit codeword (13-bit word in this embodiment) received from the recording medium will now be described with reference to Figs. 4A to 4H.

For convenience of explanation, for example, it is assumed that word values of a series of consecutive codewords received from a recording medium are 0000000000100, 0001010001010, and 0101001001001. From the conversion tables of Figs. 4A to 4H, it is understood that the first codeword 0000000000100 is assigned to the information words 0, 1, 2, 3, and 4, and that the corresponding state directions are 1, 2, 3, 4, and 5, respectively. Can be. The next codeword value is 0001010001010, which belongs to the codeword set of state 2. This means that the first codeword 0000000000100 was in state direction 2. The first codeword 0000000000100 with state direction 2 represents an information word with decimal one. Thus, the first codeword 0000000000100 is determined to represent the 9-bit information word of 000000001 with decimal one.

And, the third codeword 0101001001001 is an element of state 4. Thus, in the same manner as above, the second codeword 0001010001010 is determined to represent an information word having a decimal number of three. In the same manner, 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.

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 five, s becomes three.

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). 6 illustrates a structure of a conversion table stored in the read-only memory. In preparation for the number of 2 ^m information words, an n-bit codeword and a s-bit (2 ^s > = r) state word are required for each state r. In one embodiment of the present invention, since m = 9, n = 13, r = 5, the size of the conversion table is 5,120 bytes {= 2 ⁹ x5x (13 + 3) bits}.

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, an m input is connected to a first bus 51 for receiving an m-bit input word, and at the output of the converter 50, an n output carries an n-bit codeword. It is connected to the second bus 52 for. The s input is then connected to a third bus 53 of s-bit 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 the m-bit information word and the 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. Therefore, 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 status word. That is, one item of the combination of the m-bit codeword and the s-bit status word of FIG. 6 is determined.

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, as shown in FIG. The converter 50 outputs the n-bit codeword of the determined item 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 a 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 the next processing necessary for recording or transmission.

Recorder

FIG. 7 shows a recording apparatus for recording information, including the coding apparatus 124 of FIG. 3 according to the present invention.

As shown in FIG. 7, m-bit information is converted into a modulated signal through the coding device 124. The modulated signal generated by the coding device 124 is transferred to the write control circuit 123. The recording control circuit 123 may use the optical pickup or the laser diode 122 according to a modulation signal applied to the recording control circuit 123 so that a mark pattern corresponding to the modulation signal may be engraved on the recording medium 110. Any of the general control circuits for controlling is possible.

8 shows an example of a recording medium 110 according to the present 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. 8, the recording medium 110 according to an embodiment of the present invention includes an information pattern arranged on the track 111. In particular, FIG. 7 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

FIG. 9 illustrates a transmission apparatus for transmitting information, including the coding apparatus 124 of FIG. 3 according to the present invention. As shown in FIG. 9, the m-bit information word is converted into a modulated signal by the coding device 124. 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

10 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 drawing, 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 conversion table stored in the first searcher 102 may have a structure as shown in FIG. 11A. The conversion table structure of FIG. 11A is for the case where the codeword selected in the embodiment of FIG. 2 is used, and a total of 605 inputs (120 for states 1, 2, and 3, 122 for state 4, and state) 5 bits and 123 codeswords correspond to 3 bits in the coding direction. Therefore, the conversion table of FIG. 11A is 605x (13 + 3) bits in size, requiring 9680 bits.

In order to reduce the amount of memory used for the conversion table, the codewords are preferably classified and grouped in advance according to the coding states. In this configuration, the structure of the conversion table of the first searcher 102 is as shown in Fig. 11B. The size of the conversion table in FIG. 11B is 605x13 bits, 7865 bits, resulting in 18.75% memory savings compared to the conversion table in FIG. 11A. In the case of using the conversion table structure of FIG. 11B, when one of the 605 codewords is retrieved, the state of the codeword is state 1 if the position of the retrieved codeword is 120 or less, and state 2 from 121 to 240. , State 241 through 360, state 3 from 361 to 482, and state 5 from 483 to the end. This decision is implemented as a simple logic circuit.

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 specific one of the information words is selected using the state information from the first searcher 102 and the stored conversion table.

The conversion table stored in the second searcher 104 may have a structure as shown in FIG. 12A. The conversion table structure of FIG. 12A is for the case where the codeword selected in the embodiment of FIG. 2 is used. For the total number of 2560 combinations (= 2 ⁹ x 5) of the input code word and the state direction, the conversion table structure is 9 bits. The information words are associated with each other. Therefore, the conversion table of FIG. 12A needs 8 KBytes {= 2 ⁹ x 5x (13 + 3 + 9) bits} in size.

In order to reduce the amount of memory used for the conversion table, the codewords are preferably classified by state directions, and then grouped and stored in each state direction. That is, the next state is classified by the same codeword, and then divided and stored in order. For example, find the codewords 604 of the state direction 1 in the conversion table of FIGS. 4A-4H, store them in order from the beginning of FIG. 12B, and then in the conversion table of FIGS. 4A-4H. These two codewords (605) are found and stored. In this manner, the conversion table of FIG. 12B is completed by completing the codeword string of FIG. 12B and storing the corresponding information words in the next column.

In this configuration, the conversion table structure of FIG. 12A is reduced as shown in FIG. 12B. The size of the conversion table in FIG. 12B is (604 + 605 + 605 + 373 + 373) x (13 + 9) = 56,320 bits, i.e., 7,040 bytes, which saves 12% of the memory size compared to the conversion table of FIG.

In the case of using the conversion table structure of Fig. 12B, the second searcher 104 is presently determined according to the coding state value of the (K + 1) th codeword determined and input from the first searcher 102. The coding block of FIG. 12B to search the input K-th codeword is determined. In other words, if the coding state is 1, up to 604, 2 is 605 to 1209, 3 is 1210 to 1814, 4 is 1815 to 2187, and 5 is 2188 to the end. .

The determination of this search block is implemented by a simple logic circuit. When the search section is designated as described above, the K-th codeword is searched within the section, and the information word corresponding to the matching codeword is determined as decoded data.

For the purpose of supplementing the description only, assume that the n-bit codeword is a 13-bit codeword made using the conversion table of FIGS. 4A-4H. Referring to FIG. 5, if the (K + 1) th 13-bit codeword is 0001010001010, the first searcher 102 determines the state of the codeword as state 2 from the search of the conversion table in FIG. 11A or 11B. Further, if the K-th 13-bit codeword is 0000000000100, the second searcher 104 determines that the K-th 13-bit codeword is one of 9-bit information words having a value of decimal 0, 1, 2, 3, or 4. Determine that it represents.

And since the next state or state direction, which is state 2, is applied from the first searcher 102, the second searcher 104 uses the 13-bit codeword 0000000000100 associated with state 2 from the conversion table of FIG. 12A or 12B. It is understood that the 9-bit information word indicating the value of decimal 1 is indicated and based on this, it is determined that the K-th 13-bit codeword is a 9-bit information word indicating the value of decimal 1.

Playback device

FIG. 13 illustrates a playback apparatus including the decoder 100 of FIG. 10 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 the decoder 100 can receive according to a conventional method. The decoder 100 decodes the binary signal to obtain an m-bit information word.

Receiver

14 illustrates a receiving apparatus including the decoder 100 of FIG. 10 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 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 reduces the size of the conversion table required for decoding while making the recording medium or transmission 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. What's more, the smaller the required memory, the lower the cost of the hardware.

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 (20)

receiving an n-bit (n is integer) codeword; And And converting the n-bit codeword into an m-bit (m is an integer less than n) information word with reference to a first and second conversion table. One m-bit information word is represented by the first or second kind of n-bit codeword if the previous n-bit codeword was of the first type, and the previous n-bit codeword If n was the second type, the n-bit codewords are divided into two types and coding states belonging to two kinds, and codes belonging to different coding states, so that they are represented by the first kind of n-bit codewords. The word set is assigned to each m-bit information word so that it does not contain any common codeword, each of the n-bit codewords has a different associated state direction, and each state direction is one m-bit. When an information word is coded with the n-bit codeword, the first conversion table is assigned to indicate the next coding state among a plurality of coding states, to obtain a next n-bit codeword. N-bit codewords with the same coding state And the grouping is organized by the second conversion table, said state itdoe direction are grouped by the same n- bit code words, The second conversion table is composed of only n-bit codewords that are duplicated and allocated to different groups at least once and information words corresponding to each codeword. -The total number of bit codewords is '2mx (number of coding states)'. delete delete delete The method of claim 1, wherein the n-bit codeword is divided into p coding states of the first type and q coding states of the second type, wherein p and q are integers greater than or equal to 1, The converting step determines, by referring to the first conversion table, which of the p and q states the next n-bit codeword belongs to, and designates a search block of the second conversion table from the determined coding state value. Thereafter, the current n-bit codeword is found in the search block, and the decoding method is output as an m-bit information word corresponding thereto. delete 6. The converting method according to claim 5, wherein the converting step finds a codeword that matches an n-bit codeword in the first conversion table, and determines a corresponding coding state from a position in the conversion table of the codeword. Decoding method. 8. The method of claim 7, 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. A maximum number of zeros between consecutive ones. 9. A decoding method according to claim 8, wherein m / n is greater than 2/3, d = 1 and p + q is 5. 6. The method of claim 5, wherein the n-bit codeword of the first type ends in 0, the n-bit codeword of the second type ends in 1, and is in a coding state within the first kind. And the n-bit codewords starting with 0 and the n-bit codewords in the second type of coding state start with 0 or 1. Receives an n-bit (n is an integer) codeword and converts the n-bit codeword into an m-bit (m is an integer less than n) information word with reference to the stored first and second conversion tables. Including a transducer, One m-bit information word is represented by the first or second kind of n-bit codeword if the previous n-bit codeword was of the first type, and the previous n-bit codeword If n was the second type, the n-bit codewords are divided into two types and coding states belonging to two kinds, and codes belonging to different coding states, so that they are represented by the first kind of n-bit codewords. The word set is assigned to each m-bit information word so that it does not contain any common codeword, each of the n-bit codewords has a different associated state direction, and each state direction is one m-bit. When an information word is coded with the n-bit codeword, the first conversion table is assigned to indicate the next coding state among a plurality of coding states, to obtain a next n-bit codeword. N-bit codewords with the same coding state And the grouping is organized by the second conversion table, said state itdoe direction are grouped by the same n- bit code words, The second conversion table is composed of only n-bit codewords that are allocated at least once in different groups and information words corresponding to each codeword, and n- which is allocated at least once in different groups. And the total number of bit codewords is 2mx (number of coding states). delete delete delete 12. The method of claim 11, wherein the n-bit codeword is divided into p coding states of the first type and q coding states of the second type, wherein p and q are integers greater than or equal to 1, The transformer determines, with reference to the first conversion table, which of the p and q states the next n-bit codeword belongs to, and designates a search block of the second conversion table from the determined coding state value. And a current n-bit codeword is found in the search block and then output as an m-bit information word corresponding thereto. delete 16. The decoding of claim 15, wherein the converter looks up a codeword in the first conversion table that matches an n-bit codeword, and determines the coding state from a position in the conversion table of the codeword. Way. 18. The method of claim 17, 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. 19. The decoding apparatus of claim 18, wherein m / n is greater than 2/3, d = 1, and p + q is 5. 16. The method of claim 15, wherein the n-bit codeword of the first type ends in 0, the n-bit codeword of the second type ends in 1, and is in a coding state within the first kind. Wherein the n-bit codeword begins with 0 and the n-bit codeword in the second type of coding state starts with 0 or 1.