CN101359973B - Encoding method and encoder for balanced code and fixed weight code - Google Patents
Encoding method and encoder for balanced code and fixed weight code Download PDFInfo
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Abstract
The invention relates to an encoding method and an encoder of a balanced code or a fixed-weight code in a storage or communication system, and the balanced code is that the number of bit 1 and the number of bit 0 are identical in an output digital data of the encoder; the fixed-weight code shows that the number of bit 1 and the number of bit 0 are non-identical in an output digital data of the encoder, but the proportion of the number of bit 1 and the number of bit 0 is fixed. The encoding mode of the balanced code or the fixed-weight code distinguishes all of the available codes to a plurality of mutual non-overlapping subsets (subset), the number of bits input to the encoder with one time is fixed and can be distinguished to two parts, the first part decides which subset is used through a zoom table, and the second part decides to use a legitimate output code of the subset as output of the encoder.
Description
Technical field
The present invention is the coding method and the encoder of a coding method and encoder, especially balanced code or fixed weight sign indicating number.
Background technology
Because communication and computer industry are progressive fast, it is very universal that the high-quality audio and video information and the interactive model of diversification become, but, the high-quality audio and video information and the interactive model of diversification need transmission speed and lot of data processing faster, therefore, one is read fast and the bigger storage facilities of capacity is just thirsted for having by the consumer.
It is data to be write in the disc in regular turn in the mode of one dimension store that the light of current trend stores, improve the capacity and the storage density of disc, just must be shorter with wavelength and lens that numerical aperture (Numerical Aperture) is bigger as the element of optical read/write head, the blue light disk system that for example SONY carried out, just be to use wavelength ratio dvd pickup short blue laser and the bigger lens of numerical aperture on first watch, dwindle the luminous point that projects on the disc, further increase the density that stores.But this practice has slowly been approached the limit physically, and unrenewable such method has further increased the capacity of disc.Because the shorter ultraviolet ray of wavelength ratio blue light can't be by the protective layer of disc, and the increase of numerical aperture also arrives the limit of industry soon.Therefore, will further increase storage density and storage volume just must change from basic physical principle, and holographic (full figure) storing technology is hoped the blue light disk that continues (Blu-ray Disk, BD) or high-quality digital multi disc (HD-DVD) afterwards, become next stocking system main flow from generation to generation, its storage volume and transmission speed can significantly surmount present optical memory system.Holographic storage can store so in a large number and the basic reason of making rapid transmission of information is: holophotal system has adopted the optical mode of three degree solid spaces to store with two optical modes of spending plane spaces and has read; Its storage area and the data number that once reads will be gone up many compared to existing optical memory system more.The holographic optics framework that stores can be shown in Fig. 1 (a) and Fig. 1 (b), the optical rack composition of Fig. 1 (a) when storing wherein, and the optical element of depicting dotted line among the figure as does not need the element that uses when being illustrated in storage; The optical rack composition of Fig. 1 (b) when reading, the optical element of describing of dotted line also is that representative does not need the element that uses when reading among the figure.When storing, the light beam of high-power laser 101 emission one same tones very high (high spatial and temporal coherence) arrives another direction through reflecting element 102 with beam steering, in this example, light beam after turning to is vertical with original light beam.But have the amount of the element 103 restricted passage light beams of aperture, only near the light beam aperture can pass through, and therefore, the light beam by aperture can be considered as a quite desirable point-source of light.Lens 104 can become directional light with the point-source of light by aperture.Spectroscope 105 (splitter) can be divided into single laser light two bundles, and a branch of for being used for the signal beams 106 (signal beam) of the data of carrying, another bundle is reference beam 107 (reference beam).Data is encoded with a kind of device of " light regulator between light " 108 (spatial light modulator) by name in signal beams, numerical data 0 and 1 translates to the form of bright spot and dim spot (light and dark pixels), and with array or the page or leaf (page) mode arrange, every page of contained bit number is along with designer's difference, may have very big variation, and every page only be the minimum unit when reading, therefore, such technology can reach storage volume and the transmission speed more high than present system easily.After the signal beams 106 process reflecting elements 109 and lens 111 through " spatial light modulator " 108, accumulate on the Storage Media 112 (holographic storage media), and another road light beam that produces through spectroscope is called reference beam 107, focus on the same point of Storage Media through another reflecting element 110 with different paths, this two bundle can be because interference from the light in different paths, produce interference figure, these patterns contain the required information of reconstruction data, and hologram medium just writes down these interference figures the storage action that can finish holographic data.When reading, shown in Fig. 1 (b), the medium that store usefulness are focused on part as for signal beams and reference beam, cover signal beams, only focus on interference figure in the Storage Media with reference beam, then interference figure can be converted to the data of an one page or an array via lens 113 by detector 114.
Holographic storage system and optical memory system something in common now are: the variation of signal strength signal intensity, can cause the bad influence of decoding end.Therefore, in design during chnnel coding, the designer can allow 1 to equate haply with 0 number, and just on electric signal, that finishes yard can cause signal very little or level off to zero at the composition of direct current signal (DC) or low frequency part.
Level off to zero requirement in order to reach low-frequency component, technology one (United States Patent (USP) 6 formerly, 016, No. 330) in, the encoding mechanism of a kind of balanced code (balanced code) is provided, through the later output of coding, the requirement that satisfied 1 number and 0 number equate, therefore, when data through behind the coding of spatial light modulator, the part of high brightness and the composition of low-light level equate, therefore, if high brightness is treated as signal level 1, low-light level is partly as signal level-1, after the signal level addition of all signals is averaged, is one and is in close proximity to zero numerical value, in decoding, we can judge the signal threshold (threshold) of high brightness and low-light level and utilize viterbi algorithm (Viterbi Algorithm) that the data of coding is decoded out from signal itself.
A kind of 8 bit (B that are input as are provided in the prior art one
0B
1B
2B
3B
4B
5B
6B
7), be output as 12 bit (B
0B
1B
2B
3B
4B
5B
6B
7b
8b
9b
10b
11) balanced code, in 12 bits of output, 6 bits are that 1,6 bit is 0.Therefore, the legal output character code (codeword) that meets has 924.Then, legal output character code is divided into 8 mutual unduplicated subclass (subset S
1, S
2S
8), each subclass has 64 character codes, appoints in these 64 character codes to get two and compare, and it is inequality having 4 bits at least, and just, the minimum Hamming code of this group character code is 4 apart from (minimum Hamming distance).Moreover i subclass satisfies following equation:
(b
1+2*b
2+3*b
3+4*b
4+5*b
5+6*b
6+7*b
7+8*b
8+9*b
9+10*b
10+11*b
11-i)mod12＝0
Please refer to Fig. 2, its illustrate is the encoder schematic diagram of known finite state.With prior art one is example, the input character code 303 of 8 bits inputs to coding circuit 301, coding circuit 303 determines a current state according to the input character code, and coding circuit 303 is according to input character code 303, current state, produce the legal output character code 304 of one 12 bits with previous state.Then, export this legal output character code 304 and current state to state buffer 302, and when next time input character code 303 inputed to coding circuit 301, the data in this state buffer 302 promptly were expressed as previous state.And store in the coding circuit 303 zoom table (look up table) make this coding circuit 303 can be according to input character code 303, current state, produce the legal output character code 304 of one 12 bits with previous state.
That is, be to use the encoder (finite state encoder) of finite state at coding side, use the reason of finite state encoder, mainly be because use the finite state encoder, could use viterbi algorithm to reach the best efficiency of maximum approximate (maximum likelihood) decoding in decoding end.
Disclosed embodiment in the technology one formerly, be that 8 bits input with single pen is divided into two parts, first partly has only 2 bits, these two bits can determine 4 finite state a (00), b (01), c (10), d (11) altogether, and coding can be made as initial state a (00) at first usually, by the state that present character code determined, and the state that previous character code determined, and, find the relative subclass that is used for encoding according to the corresponding relation that table one provided.For example: initial condition is a (00), and preceding two bits are 00 in 8 bits of the first stroke data, state a (00) just, it is a (00) that look-up table one obtains original state, current state still is a (00), pairing subclass is combined into S1, so choose S1, as code list of Hanzi, 64 character codes that S1 is contained are done an arrangement according to designer's planning, and each character code has the index code (index) of one 6 bits corresponding with it, and the second portion of input data is made of 6 bits, these 6 bits are so just just can form the sign indicating number of the legal output character code of decision.For example: the second portion of input data is 001000, expression, and Shu Chu character code is subclass S at last
1In the 8th character code.
The state of table one prior art one and the zoom table of subclass
Prior art two (JJAP, Vol 401 (2002) pp1763-1766) using identical principle and method, just relaxed in each character code the restrictive condition that the number of 1 number and 0 must equate, is example with encoding rate 9/12, the encoder of this sign indicating number is imported the character code B of 9 bits at every turn
0B
1B
2B
3B
4B
5B
6B
7B
8, output then is the character code b of 12 bits
0b
1b
2b
3b
4b
5b
6b
7b
8b
9b
10b
11, wherein legal output character code is " 0 " for 5 bits are arranged, and 7 bits are " 1 ", or have 7 bits to be " 0 ", and 5 bits are " 1 ".Therefore, available character code has 1584 kinds.
Moreover i subclass (Si) will satisfy following equation: (b
1+ 2*b
2+ 3*b
3+ 4*b
4+ 5*b
5+ 6*b
6+ 7*b
7+ 8*b
8+ 9*b
9+ 10*b
10+ 11*b
11-I) mod 12=0.According to above-mentioned rule, can select subclass S
0-S
7, with subclass S
0-S
7" 0 ", " 1 " exchange after, can obtain S
8-S
15Encoder is being received the input character code B of 9 bits
0B
1B
2B
3B
4B
5B
6B
7B
8The time, character code be will import and two parts, wherein B will be divided into
0B
1B
2As present state (Present State), add previous state (Previous State) and the table two that is stored in advance in the internal memory, the subclass S that can obtain choosing
i, according to the subclass S that chooses
iLatter half B with the input character code
3B
4B
5B
6B
7B
8Be used as index (index), find last legal output character code b
0b
1b
2b
3b
4b
5b
6b
7b
8b
9b
10b
11, this improvement is because relaxed the restriction of legal output character code, equates from the number of original " 1 " and " 0 " is essential, be loosened to standard from a plurality of character codes, the number of " 1 " and " 0 " will equate, this situation below is referred to as virtual balanced code (pseudo balance code).
When the restriction of coding when balanced code is loosened to virtual balanced code, the encoding rate of I/O can promote, the capacity that makes unit are or volume to store has increased.And the present invention is compared to prior art one and prior art two, and the performance behind (legal output character code is balanced code or virtual balanced code) under the identical restrictive condition its coding has further to promote.
The state of table two prior art two and the zoom table of subclass
Summary of the invention
The invention provides a kind of zoom table method for designing of finite state encoder, use the encoder in a finite state, this method comprises the following step: the bit number and the restrictive condition that at first determine the legal output character code of this encoder; The legal output character code of this restrictive condition is satisfied in collection; The bit number of the input character code of decision encoder; The character code that satisfies this restrictive condition is divided into the experimental process set according to a specific mathematical equation; Determine the character code number in each subclass; And the corresponding relation that determines this encoder current state, previous state and a certain group of character code subclass, this corresponding relation forms a zoom table, this zoom table has the subclass number that the uses state number greater than the finite state encoder, and less than the state number of the finite state encoder of twice.
In the method provided by the present invention, be to use in the encoder of finite state, and the state number of encoder can be 4 or 8.And the restrictive condition that all legal output character codes all satisfy is: the number of the bit 1 of legal output character code and the number of bit 0 equate that this is so-called balanced code (balanced code); Even the number of the number of bit 1 and bit 0 is unequal, also must satisfy, the bit 1 of legal output character code and the number ratio of bit 0 are fixed.After all possible legal output character code found out, next, these legal output character codes are divided into the experimental process set, the legal output character code in the identity set, its minimum Hamming code is apart from more than or equal to a specific natural number.And the method that legal output character code is distinguished into different subclass is: decide certain legal output character code can be sorted in which subclass by some bit and some additions, multiplying of input in the character code.And each subset word number of codes is determined by the state number of limited encoder and the bit number of input character code.That the corresponding relation of the current state in the finite state encoder, previous state and a certain group of character code subclass is linked together is a zoom table (lookup Table), the design condition of this zoom table is: make under the situation that hedge figure can restrain, with minimum subclass number, finish the design of zoom table.
The invention provides a kind of use comprises at the encoder that holography stores:
One first read-only memory, this read-only memory are deposited the legal output character code that is divided into the experimental process set; Also has one second read-only memory in addition, this read-only memory stores the zoom table of a state to subclass, the subclass number that this zoom table uses is greater than state number and less than the state number of twice, and the design of this zoom table is: make under the situation that hedge figure can restrain, with minimum subclass number, finish the design of coding schedule; Also have a buffer in addition, deposit the last time state variable of coding; And a coding circuit, can from this first read-only memory and this second read-only memory, find out the legal output character code of a regular length according to the input character code of a regular length and the content of this buffer.
Description of drawings
For further specifying concrete technology contents of the present invention, below in conjunction with embodiment and accompanying drawing describes in detail as after, wherein:
Fig. 1 (a) is that holography is stored in the optics framework when storing.
Fig. 1 (b) is that holography is stored in the optics framework when reading.
Fig. 2 is the schematic diagram of finite state encoder.
Fig. 3 is that state number is 4 hedge figure (Trellis Diagram).
Fig. 4 is that state number is 8 hedge figure.
Fig. 5 is the design procedure of encoder zoom table
Fig. 6 is the schematic diagram of finite state encoder of the present invention.
Embodiment
The present invention compares with prior art, first difference of the present invention is: the character code of preceding two row can repeat in the zoom table of state and subclass, in contrast to and adopt 4 * 4 the state and the zoom table (seeing Table) of subclass in the prior art one, prior art one has adopted eight kinds of different subclass S
0-S
7, and utilize hedge figure (trellis diagram) to find only to need 6 or 7 groups of different subclass just can allow hedge figure (trellis diagram) reach convergence.Moreover, ining contrast to 8 * 8 states that adopted in the prior art two and the zoom table (seeing Table two) of subclass, prior art has adopted 16 kinds of different subclass S
0-S
15And utilize hedge figure (trellis diagram) only need to find the different subclass of 12-15 group just can allow hedge figure (trellis diagram) reach convergence, therefore, our encoder does not just need so much group of different subclass, so can significantly reduce the needed internal memory number of zoom table in the encoder.
The present invention compares with prior art, and another special character of the present invention is: the subset of computations that is adopted in the prior art is closed S
iMode be: (b
1+ 2*b
2+ 3*b
3+ 4*b
4+ 5*b
5+ 6*b
6+ 7*b
7+ 8*b
8+ 9*b
9+ 10*b
10+ 11*b
11-i) mod 12=0.And and then find first bit b of legal output character code
0Irrelevant with the formula of determinant set, therefore, the present invention closes S with subset of computations
iMode change into:
(b
0+2*b
1+3*b
2+4*b
3+5*b
4+6*b
5+7*b
6+8*b
7+9*b
8+10*b
9+11*b
10-i)mod12＝0。Therefore, the bit number of legal output character code just can drop to 11 bits from 12 bits, so can more efficiently utilize available character code.
According to above feature, the invention provides the zoom table method for designing of a systematic a kind of finite state encoder, as shown in Figure 5, this method comprises the following step: at first determine this encoder a restrictive condition (step 501), with the bit number (step 502) of legal output character code, in the present invention, this restrictive condition is exactly that this encoder of decision is output as balanced code or fixed weight sign indicating number; After determining the bit number and restrictive condition of legal output character code, just can calculate and meet the legal output word number of codes of restrictive condition, this number can influence the bit number of the input character code of encoder.
Then, go to collect the legal output character code (step 503) that satisfies this restrictive condition (balanced code or fixed weight sign indicating number) with regard to the available computers program; When all legal output character codes collect finish after, can determine the bit number (step 504) of the input character code of (limited) state number of encoder and encoder; Then, to satisfy the legal output character code of this restrictive condition (balanced code or fixed weight sign indicating number) and be divided into experimental process set (step 505) according to a specific mathematical equation, the number of subclass is by the state number decision of encoder, if state number is 4, we need 6-7 subclass, if state number is 8, we need 12-15 subclass, formerly technology and embodiment that some the present invention the carried operator S set of falling into a trap
iMathematical equation be:
(b
1+2*b
2+3*b
3+4*b
4+5*b
5+6*b
6+7*b
7+8*b
8+9*b
9+10*b
10+11*b
11-i)mod12＝0。
Next, determine legal output word number of codes (step 506) in each subclass according to the state number of input bit number of character code and encoder; Determine this encoder current state with computer program at last, the corresponding relation of previous state and a certain group of character code subclass, this corresponding relation forms a zoom table (step 507), this zoom table is characterised in that: the subclass number that the uses state number greater than the finite state encoder is arranged, and state number less than the finite state encoder of twice, if the zoom table after the decision can allow hedge figure (Trellis Diagram) restrain (step 508), zoom table has just been finished (step 509), if can't allow hedge figure convergence, then change the corresponding relation that to restrain, till hedge figure convergence.
According to the coding method of balanced code of the present invention and fixed weight sign indicating number, the present invention proposes several embodiment:
First embodiment (encoding rate is 4/6 virtual balanced code):
In first embodiment, the input character code of encoder has four bit B
0B
1B
2B
3, legal output character code then has six bit b
0b
1b
2b
3b
4b
5, wherein, legal output character code has two kinds: a kind of is to have 2 bits to be " 1 " in the middle of 6 bits exporting, and other four bits are " 0 "; Another legal output character code then is to have 2 bits to be " 0 " in the position of exporting, and other four bits are " 1 ".When encoder is received an input character code B
0B
1B
2B
3The time, get B
0B
1As current state, therefore, have four kinds of possible state: a (00), b (01), c (10), d (11), these two kinds of legal character codes respectively have 15, always have 30 legal character codes, so we need one 4 * 4 zoom table, such zoom table needs 6-7 different subclass, therefore, we are divided into 7 subclass with 30 kinds of legal character codes.Character code in these 7 subclass satisfies smallest hamming distance and is 4 requirement.These 7 subclass and the character code that is contained are respectively:
S
0＝[000011；011101；101110；110000]；
S
1＝[000101；011110；100010；111001]；
S
2＝[000110；011011；100001；111100]；
S
3＝[001001；010111；100100；111010]；
S
4＝[001010；010001；101101；110110]；
S
5＝[001100；010010；101011；110101]；
S
6＝[001111；010100；101000；110011]；
When encoder is received an input character code B
0B
1B
2B
3The time, get B
0B
1As current state, therefore, have four kinds of possible state: a (00), b (01), c (10), d (11), and B
2B
3, then be an index, can be used as the foundation of choosing central certain the legal output character code of subclass.From the hedge figure of Fig. 3 as can be known, the previous state of this encoder has four kinds of possible states, and current state also is to have four kinds of possible states, and the previous state that each is possible all can arrive four kinds of different current states.Therefore after the convergence test through hedge figure, can obtain the zoom table of one 4 * 4 state subgroup set, this is shown as shown in Table 3:
The state of table three 4/6 virtual balanced code is to character code subclass zoom table
Wherein (p q) can be (4,5,5,4) or (4,6,5,6) for m, n ... or the like, can be according to the practical situation in when coding, choose a kind of Hamming code apart from bigger character code as output.For instance, in coding, if previous state is a (00), and the input character code of receiving is B
0B
1B
2B
3=1010, then encoder can be with B
0B
1=10 are used as present state, and just present state is c (10), and according to table three, we can learn S
2Be the subclass that is selected, and B
2B
3=10, expression S
2In the middle of index be that 10 character code can be selected, if the index of each subclass since 00, S
2In the 3rd character code (index is 10) can be selected and as the output of encoder.Therefore, in the case, encoder be output as 100001 at last.
Second embodiment: (encoding rate is 8/11 virtual balanced code)
Second embodiment is with 8 bit B
0B
1B
2B
3B
4B
5B
6B
7The input character code, change into the legal output character code b of 11 bits
0b
1b
2b
3b
4b
5b
6b
7b
8b
9b
10A kind of coding method.The characteristic of this coding method is: have 6 bits " 0 " or 5 bits to be " 0 " in the legal output character code; Legal output character code like this has 462 kinds.When encoder is received input character code B
0B
1B
2B
3B
4B
5B
6B
7The time, can be with first three bit B of input character code
0B
1B
2Be used as present state, therefore, contingent state has 8 kinds: a (000), b (001), c (010), d (011), e (100), f (101), g (110), h (111).Learn that from the hedge figure of Fig. 4 the previous state of this encoder has eight kinds of possible states, current state also is to have eight kinds of possible states, and the previous state that each is possible all can arrive eight kinds of different current states.In order to finish coding, we need one 8 * 8 zoom table, and such zoom table needs 12-15 different subclass at least, in order to allow internal memory use amount energy minimization, therefore 462 kinds of character codes is divided into 12 sub-S set
0-S
11, 32 legal output character codes are arranged in each subclass, legal its smallest hamming distance of output character code (minimum Hamming Distance) in the same subclass is 4, its practice is: the legal output character code that is assigned to certain subclass Si will meet:
(b
0+2*b
2+3*b
3+4*b
4+5*b
5+6*b
6+7*b
7+8*b
8+9*b
9+10*b
10+11*b
11-i)mod12＝0。Therefore, after the constringent test of hedge figure (Trellis Diagram), we are with previous state, current state and subclass S
0-S
11Make a zoom table, as shown in Table 4.
The state of table four 8/11 virtual balanced code is to character code subclass zoom table
The finite state encoder must be stored into the legal output character code of the content of table four and each subclass is used as zoom table in the internal memory.For instance, when coding, receive the B of 8 bits
0B
1B
2B
3B
4B
5B
6B
7=01001000 input character code is taken out the preceding 3 bit B of input character code
0B
1B
2=010 as current state, that is to say that current state is c (010), supposes that previous state is f (101), and according to table four, we can learn subclass S
8In legal output character code for output candidate's character code, then choose B
3B
4B
5B
6B
7=01000 as index, then at S
8In to choose index be that 01000 legal output character code is as legal output character code.
The 3rd embodiment: (encoding rate is 9/12 balanced code)
The 3rd embodiment is the input character code B with 9 bits
0B
1B
2B
3B
4B
5B
6B
7B
8Convert the legal output character code b of 12 bits to
0b
1b
2b
3b
4b
5b
6b
7b
8b
9b
10b
11Coding method.Have 6 bits to be " 0 " in the middle of the legal output character code of 12 bits, other 6 bits are " 1 ".The legal output character code that satisfies such restrictive condition has 924 kinds.When encoder is received input character code B
0B
1B
2B
3B
4B
5B
6B
7B
8The time, can be with first three bit B of input character code
0B
1B
2Be used as present state, therefore, contingent state has 8 kinds: a (000), b (001), c (010), d (011), e (100), f (101), g (110), h (111).Learn that from the hedge figure of Fig. 4 the previous state of this encoder has eight kinds of possible states, current state also is to have eight kinds of possible states, and the previous state that each is possible all can arrive eight kinds of different current states.In order to finish coding, we need one 8 * 8 zoom table, and such zoom table needs 12-15 different subclass at least, and in order to allow internal memory use amount energy minimization, we are divided into 12 sub-S set with this character code of 924 kinds
0-S
11, 64 legal output character codes are arranged in each subclass, the smallest hamming distance between these 64 character codes is 4.I sub-S set
iIn legal output character code must satisfy:
(b
0+2*b
1+3*b
2+4*b
3+5*b
4+6*b
5+7*b
6+8*b
7+9*b
8+10*b
9+11*b
10-i)mod12＝0。Therefore, we are with previous state, current state and subclass S
0-S
11Corresponding relation finish the convergence test of hedge figure after, can obtain a zoom table, as shown in Table 5.
The state of table five 9/12 balanced code is to character code subclass zoom table
The finite state encoder must be stored into the legal output character code of the content of table five and each subclass is used as zoom table in the internal memory.For instance, when coding, receive the B of 9 bits
0B
1B
2B
3B
4B
5B
6B
7B
8=010010000 input character code is taken out the preceding 3 bit B of input character code
0B
1B
2=010 as current state, that is to say that current state is c (010), supposes that previous state is f (101), and according to table four, we can learn subclass S
8In legal output character code for output candidate's character code, then choose B
3B
4B
5B
6B
7B
8=010000 as index, then at S
8In to choose index be that 010000 legal output character code is as legal output character code.
The 4th embodiment: (encoding rate is 9/12 fixed weight sign indicating number)
The 4th embodiment is the input character code B with 9 bits
0B
1B
2B
3B
4B
5B
6B
7B
8Convert the legal output character code b of 12 bits to
0b
1b
2b
3b
4b
5b
6b
7b
8b
9b
10b
11Coding method.There are 5 bits to be " 0 " in the middle of the legal output character code of 12 bits, have 7 bits to be " 1 ".The legal output character code that satisfies such restrictive condition has 792 kinds.When encoder is received input character code B
0B
1B
2B
3B
4B
5B
6B
7B
8The time, can be with first three bit B of input character code
0B
1B
2Be used as present state, therefore, contingent state has 8 kinds: a (000), b (001), c (010), d (011), e (100), f (101), g (110), h (111).Learn that from the hedge figure of Fig. 4 the previous state of this encoder has eight kinds of possible states, current state also is to have eight kinds of possible states, and the previous state that each is possible all can arrive eight kinds of different current states.In order to finish coding, we need one 8 * 8 zoom table, and such zoom table needs 12-15 different subclass at least, in order to allow internal memory use amount energy minimization, this character code of 792 kinds is divided into 12 sub-S set
0-S
11, 64 legal output character codes are arranged in each subclass, the smallest hamming distance between these 64 character codes is 4.I sub-S set
iIn legal output character code must satisfy:
(b
0+2*b
1+3*b
2+4*b
3+5*b
4+6*b
5+7*b
6+8*b
7+9*b
8+10*b
9+11*b
10-i)mod12＝0。Therefore, we are with previous state, current state and subclass S
0-S
11Corresponding relation finish the convergence test of hedge figure after, can obtain a zoom table, as shown in Table 6.
The state of table six 9/12 fixed weight sign indicating number is to character code subclass zoom table
The finite state encoder must be stored into the legal output character code of the content of table six and each subclass is used as zoom table in the internal memory.For instance, when coding, receive the B of 9 bits
0B
1B
2B
3B
4B
5B
6B
7B
8=0,100 10000 input character code is taken out the preceding 3 bit B of input character code
0B
1B
2=010 as current state, that is to say that current state is c (010), supposes that previous state is f (101), and according to table four, we can learn subclass S
8In legal output character code for output candidate's character code, then choose B
3B
4B
5B
6B
7B
8=010000 as index, then at S
8In to choose index be that 010000 legal output character code is as legal output character code.
The 5th embodiment (encoding rate is 8/12 balanced code):
Among the 5th embodiment, the input character code of encoder has 8 bits B
0B
1B
2B
3B
4B
5B
6B
7, legal output character code then has 12 bit b
0b
1b
2b
3b
4b
5b
6b
7b
8b
9b
10b
11, wherein, there are 6 bits to be " 1 " in the legal output character code, other 6 bits are " 0 ", so legal output character code has 924.When encoder is received an input character code B
0B
1B
2B
3B
4B
5B
6B
7The time, get B0B1 as current state, therefore, have four kinds of possible state: a (00), b (01), c (10), d (11), therefore we need one 4 * 4 zoom table, and such zoom table needs 6 different subclass at least, according to the method for prior art one, we deliberately are distinguished into 12 subclass with 924 legal output character codes of institute, and the legal output character code in i sub-S set i must satisfy:
(b
0+2*b
1+3*b
2+4*b
3+5*b
4+6*b
5+7*b
6+8*b
7+9*b
8+10*b
9+11*b
10-i)mod12＝0。Therefore, the number of subclass just is the twice that minimum needs number, and we can appoint and get wherein 6 subclass and make a zoom table, make another zoom table with 6 remaining subclass.When coding, import the input character code of one 8 bit at every turn, just having two different subclass can choose from, and can select the lower legal output character code of higher or wrong incidence of reliability as output according to the characteristic of channel.So, can under the requirement of identical encoding rate, reach,, have significantly and improve especially for error rate than prior art one better usefulness.
For instance, receive an input character code B when encoder
0B
1B
2B
3The time, get B
0B
1As current state, therefore, have four kinds of possible state: a (00), b (01), c (10), d (11), and B
2B
3, then be an index, can be used as the foundation of choosing central certain the legal output character code of subclass.Learn that from Fig. 2 the previous state of this encoder has four kinds of possible states, current state also is to have four kinds of possible states, and the previous state that each is possible all can arrive four kinds of different current states.So after the convergence test through hedge figure, can obtain the zoom table of two 4 * 4 state subgroup set, this table is shown in table six and table seven:
The state of table six 8/12 balanced code is to character code subclass zoom table
The state of table seven 8/12 balanced code is to character code subclass quick checking supplementary table
In coding, if previous state is a (00), and the input character code of receiving is B
0B
1B
2B
3B
4B
5B
6B
7=10001000, then encoder can be with B
0B
1=10 are used as present state, and just present state is c (10), and according to table three, we can learn that S2 or S9 are the subclass that is selected, and B
2B
3B
4B
5B
6B
7=00 1000, expression S
2Or S
9In index be that 001000 character code can be selected, we can choose a legal preferably output character code of the characteristic of channel from two legal output character codes, as output.
Please refer to Fig. 6, its illustrate is encoder of the present invention.That is to say above embodiment, all can utilize the encoder of Fig. 6 to realize, this encoder comprises: one first read-only memory 601 is used for depositing the legal output character code that is divided into as if most subclass; One second read-only memory 602 is used for storing the zoom table of a state to subclass; One buffer 603 is deposited previous state; And a coding circuit 604, can from this first read-only memory and this second read-only memory, find out the legal output character code of a regular length according to the input character code of a regular length and the content of this buffer.
That is, when input character code 605 inputs to coding circuit 604, coding circuit 604 determines a current state according to the input character code, and coding circuit 604 reads second zoom table that second read-only memory uses according to current state and previous state and closes to obtain a particular subset.Then, read first zoom table that first read-only memory uses to obtain the legal output character code of this regular length so that this particular subset is incompatible.And current state can be kept in to state and accounted for storage 603, and when next time input character code 605 inputed to coding circuit 604, the data in this state buffer 603 promptly were expressed as previous state.
According to method provided by the present invention; we can successfully solve the problem described in prior art; and reached the main purpose of the present invention's development; but the present invention invents to such an extent that thought and be to modify as all by the personage Ren Shi craftsman who has the knack of this skill, right neither content of taking off as the desire protection of attached claim institute.
Claims (9)
1. the zoom table method for designing of a finite state encoder is used at a finite state encoder, it is characterized in that this method comprises the following step:
Determine the bit number and a restrictive condition of the legal output character code of this finite state encoder;
Most legal output character codes of this restrictive condition are satisfied in collection, wherein this all satisfied restrictive condition of those legal output character codes is: the number of the bit 1 of legal output character code and the number of bit 0 equate, perhaps be: the ratio of the number of the bit 1 of legal output character code and the number of bit 0 is fixing, and this ratio is not equal to 1;
By the number of those legal output character codes, determine the bit number of the input character code of this finite state encoder;
By the bit number of the input character code of this finite state encoder and the bit number of legal output character code, determine the state number of this finite state encoder;
According to the state number of this finite state encoder, those legal output character codes that satisfy this restrictive condition are divided into most subclass according to a specific mathematical equation, wherein this mathematical equation is: (b
0+ 2*b
1+ 3*b
2+ 4*b
3+ 5*b
4+ 6*b
5+ 7*b
6+ 8*b
7+ 9*b
8+ 10*b
9+ 11*b
10-I) mod12=0;
Determine the legal output word number of codes in those subclass; And
Determine the corresponding relation of this encoder current state, previous state and a certain group of character code subclass, this corresponding relation forms a zoom table, this zoom table has the subclass number that the uses state number greater than the finite state encoder, and less than the state number of the finite state encoder of twice
Wherein determine the condition of the corresponding relation of this zoom table current state, previous state and a certain group of character code subclass to be: to make under the situation that hedge figure can restrain,, finish the design of zoom table with minimum subclass number.
2. the zoom table method for designing of finite state encoder as claimed in claim 1 is characterized in that, the legal output character code in the wherein same subclass, and its minimum Hamming code distance is more than or equal to a specific natural number.
3. the zoom table method for designing of finite state encoder as claimed in claim 1 is characterized in that, wherein the state number of the encoder of this finite state is 4.
4. the zoom table method for designing of finite state encoder as claimed in claim 1 is characterized in that, wherein the state number of the encoder of this finite state is 8.
5. the zoom table method for designing of finite state encoder as claimed in claim 1 is characterized in that, wherein this specific mathematical equation is made of some bit and some additions, multiplying of input in the character code.
6. a use is characterized in that at the finite state encoder that holography stores, and comprises:
One first read-only memory, this read-only memory are deposited most legal output character codes that are divided into most subclass, and wherein those legal output character codes are divided into this majority subclass according to a specific mathematical equation, and this mathematical equation is:
(b
0+2*b
1+3*b
2+4*b
3+5*b
4+6*b
5+7*b
6+8*b
7+9*b
8+10*b
9+11*b
10-i)mod12＝0；
One second read-only memory, this read-only memory stores one the zoom table of a state to this majority subclass, the subclass number that this zoom table uses is greater than state number and less than the state number of twice, and the design of this zoom table is: make under the situation that hedge figure can restrain, with minimum subclass number, finish the design of coding schedule;
One buffer is deposited the last time state variable of coding; And
One coding circuit, can be according to the input character code of a regular length and the content of this buffer, from this first read-only memory and this second read-only memory, find out the legal output character code of a regular length, wherein the number of the number of the bit 1 of the legal output character code of this finite state encoder and bit 0 equates, perhaps the ratio of the number of the number of the bit 1 of the legal output character code of this finite state encoder and bit 0 is fixing, and this ratio is not equal to 1.
7. the finite state encoder that use as claimed in claim 6 stores in holography, it is characterized in that, wherein be stored in most the legal output character codes in this first read-only memory, the legal output character code in the identity set, its minimum Hamming code distance is more than or equal to a specific natural number.
8. use as claimed in claim 6 is characterized in that at the finite state encoder that holography stores wherein the state number of the encoder of this finite state is 4.
9. use as claimed in claim 6 is characterized in that at the finite state encoder that holography stores wherein the state number of the encoder of this finite state is 8.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6016330A (en) * | 1996-10-18 | 2000-01-18 | International Business Machines Corporation | Encoding and detection of balanced codes |
| CN1308761A (en) * | 1998-05-05 | 2001-08-15 | 奥普蒂林克有限公司 | System and method for recording of information on a holographic recording medium, preferably an optical card |
| CN1728245A (en) * | 2004-07-29 | 2006-02-01 | 凌阳科技股份有限公司 | Optical memory and recording system, and processing method |
-
2007
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6016330A (en) * | 1996-10-18 | 2000-01-18 | International Business Machines Corporation | Encoding and detection of balanced codes |
| CN1308761A (en) * | 1998-05-05 | 2001-08-15 | 奥普蒂林克有限公司 | System and method for recording of information on a holographic recording medium, preferably an optical card |
| CN1728245A (en) * | 2004-07-29 | 2006-02-01 | 凌阳科技股份有限公司 | Optical memory and recording system, and processing method |
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