JPS6043263A - Encoding and decoding system - Google Patents

Abstract

PURPOSE:To obtain an encoding system which facilitates a self-clocking by converting some of 0 code in a code word string having a maximum inversion interval in a 3PM system into 1 code for encoding into a binary data string, and reconverting the data string for decoding. CONSTITUTION:And encoder 13 converts a data word with 3-bit length into a code word with 6-bit length according to a conversion rule and a logical operation is performed. When a code word 101 is detected, the output of the encoder 13 and the output 101 of a 6-bit register 16 are converted into 010 with the output of a detector 15. The code conversion from a table (a) to a table (b) is carried out by detectors 17, 20, and 21 and exclusive ORs 23, 24, 25, 26, 27, and 29, and a code word string wherein the maximum number of 0s between the adjacent 1s is limited to 8 is outputted to a terminal 30. Thus a specific pattern is detected when the number of 0s between the adjacent 1s is large and converted into a code word pattern that the 3PM system does not have to limit the number with the succeeding 0s by this encoding system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to information 1. This invention relates to a digital encoding/decoding method used in an input-C output system.

[Technical background of the invention and its problems]

As an example of an encoding/decoding method used in a magnetic recording/reproducing device, Geo-V.
``A New Look-Ahe Code to Increase Data Density'' by Jaco, Ky.
ad Code for Increased Data
Density) J (IEEE Transactions on Magnetics IVIAG-13 No. 5,
September 1977, page 1202 et seq.) is 3PM (Thrce
This paper outlines an encoding/decoding method known as the Po5tion Modulation method. This aP
In the M method, data is separated into 3-bit units and the 3-bit data word is converted into a 6-bit code word using the conversion rules shown in Table 1, and then the code word 1 is converted into a 6-bit code word.
01 is converted to 010, and further inversion (transition) is performed at the code word "1". Various similar encoding/decoding systems have been proposed in the past, including Japanese Patent Laid-Open No. 54-80726. When performing magnetic recording and reproducing using these encoding/decoding methods, the longer the minimum reversal interval Tm1n between two adjacent reversals, the higher the data recording density, which is preferable, and the shorter the maximum reversal interval Tmax, the higher the clock recovery becomes easy. In the case of the aPM method, when the period of a pit cell of a data word is T, the minimum inversion interval Tmin is 1.5T, and the maximum inversion interval Tmax is 6T. Therefore, when a data string is encoded and recorded using this 3PM system, there is a drawback that self-clocking during reproduction is difficult because the maximum inversion interval is large.

Table 1 [Object of the Invention] The present invention was made in consideration of the above circumstances, and its purpose is to provide an easy-to-use self-clock system with a long minimum inversion interval and a shorter maximum inversion interval than the 3PM system. The purpose of this invention is to provide a unique encoding/decoding method.

[Summary of the invention]

In the present invention, the block length of the data word is 3 bits,
After converting to codewords according to the same conversion rules as in the aPM method, some of the 0'' codes in the codeword sequence that indicate the maximum inversion interval in the aPM method are changed from the ones that exist in the conventional aPM method due to the relationship with the preceding and succeeding groups. Convert to 1” code so that the code word pattern is not
A value data string is encoded, and the encoded codeword string is decoded by performing the inverse transformation of the above transformation.

〔Effect of the invention〕

Thus, according to the invention, the number of 60'' between adjacent '°1'' of the codeword sequence is at least 2 and at most 8.
When this is inverted where the code word 1'' exists, the minimum inversion interval Tm1n is 1.5T.
The maximum reversal interval Tmax is 4.5T.

However, T is the bit cell period of the data word.

Therefore, it is possible to record information with a sufficiently short maximum inversion interval while keeping the minimum inversion interval the same as that of the 3PM method, which has the advantage that self-clocking during reproduction is easy.

[Embodiments of the invention]

Hereinafter, a variation of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of an information recording/reproducing apparatus constructed by applying the encoding/decoding method of the present invention, where 1 is an encoding apparatus and 2 is a decoding apparatus. The encoding device @1 encodes the input binary data string into a codeword string as explained below, and the recording device 3 inputs the codeword string and records 1''' in the codeword string. Each time the recording medium 4 is detected, the recording medium 4 is inverted and the information is recorded on the recording medium 4.The information recorded on the recording medium 4 is transferred to the reproduction device
The reproduced data is reproduced by the decoding device 2, and the original binary data string is reproduced by skipping the code conversion process that is the reverse of the encoding process.

By the way, encoding in this method is performed as follows. In the encoding device 1, first, the input binary data string was divided into 3-bit data words, and converted into 6-bit code words using the conversion rules shown in Table 1, which are similar to the 3PM method. After the code word "101'" is "0"
From the relationship between the codewords of the groups before and after the codewords converted in this way, the codeword string of 17Q 2 (a) is further converted into the codeword string of Table 2(b). Convert to

Here, P 1+ P 2 to P6 are the current codeword group, P 11P2 to P6 are the code words of the previous group, and P+, P2 to P6 are the code words of the next group.

! (The x in 2 represents the bit of neglect in par 1'' or u071. In the conversion of Table 2, td is tl 1
At the time of 71, both P+ and P2+P3 become 0", so P
4+P s +P 6+P If 1+P2 are both 1 "0", convert Ps and P6 from 0" to "1". Also, P
When 6 is u1'', both P a + P41 P s become II OI+, so P 6 + P 1 * P
2 are both 10718, Ps is changed from 0” (11j
Convert to l. When PI and Ps are ``1'', P2
, Ps 1P31P4 are both 41011, so P
4. If Ps 1P61PI IF5 are both 0'', convert P6 and Ps from °0'' to °゛1'',
Convert P et al. from °゛l" to "0". Through such conversion, the maximum number of "0"s between adjacent 1"s in the codeword string is reduced, and after the conversion according to Table 2, the maximum number of "0"s is reduced to 8. Individually, the maximum reversal interval Tmax is reduced from 6.0T in the 3PM system to 4.5T. Therefore, we set the minimum reversal interval to 15
T is the same as the aPM method, and the maximum reversal interval is 4.5T.
Since it can be made sufficiently short, 1 of the codeword string
When recording information by inverting the recording signal each time `` is detected, the recording density is high, and self-clocking during normal operation is easy.

Such encoding processing is performed as follows in FIG. 2. The input binary data string is input in series from a terminal 11 to a 3-bit shift register 12, outputted in parallel as 3 bits, and applied to an encoder 13. encoder 13
is a circuit that converts a 3-bit long data word into a 6-bit long code word according to the conversion rules shown in Table 1.
3! Codeword P 1 + P 2 + P 3
If r P 4 + P 5 + P 6 is shifted, the following logical operation is performed. P6 is always 0''.

PI = AB + AC (11 P2 = AB (2) P3 = ABC (3) P4 = ABC + ABC (41 P5 = ABC + ABC + ABCf5) The output Pl of the encoder 13 is output to the exclusive OR 14 and the detector 15, and the output P2 is a 6-bit register. 16 and the output P31P41P51P6 to the detector 17 is added to the 6-bit register 16. Ps, P of the 6-bit register 16
The output of 6 is applied to the detector 15 to detect 1 of the codeword sequence.
01 is detected. 6-bit register P 5 + P
The output of 6 is exclusive or 18.19 respectively.
and when the code word 101 is detected by the detector,
The output of the detector 15 causes the output P1 of the encoder 13 and 6
Output P5 of bit register 16. P6 is changed sign and 101 is converted to 010.

The outputs P 1 + P 2 of the 6-bit register are both sent to the detector 20° 21 and the 6-bit register 22, the output P3 is sent to the exclusive OR 23, and the output P4 is sent to the detector 17 and the 6-bit register 22.
Exclusive OR 1 added to bit register 22
The output of 8.19 is exclusive OR 24.
25 to the 6-bit register 22. Further, the output of exclusive OR 23 is applied to 6-bit register 22 via exclusive OR 26 and 27. The outputs of Pl, P4, and Ps of the 6-bit register 22 are connected to the detector 21 and the 6-bit shift register 28 with parallel inputs.
The output of P2°Ps is applied to the 6-bit shift register 28, and the output of P6 is applied to the 6-bit shift register 28 via the detectors 17, 20. Detector 17 connected in this way
is P6=I in Table 2 P4=P5=Pe=Pt=P
This is a circuit that detects 2=0, and its output is connected to exclusive OR 23.25 to change the sign of Ps and P6 to "0".
” to “1”. The detector 20 converts P in Table 2.
6=1. This circuit detects P6=P1; P2=0, and its output is connected to the exclusive OR 26 to convert the sign of Ps from 0" to 1". Unfortunately, the detector 21 has P1=Ps=1, P4=P5=P6= in Table 2.
This is a circuit that detects P]=p2=o, and its output is added to Ex/-Sivor 24, 27.29 to output P6 and Ps.
change the sign of Ps from 0'' to 11'' and change the sign of Ps from Pa1# to I'
Convert to 0#. That is, detectors 17, 20 . ．． The sign conversion from (a) to (b) in Table 2 is performed by A code word string limited to eight pieces is output to terminal 3o.

In this way, the encoding process according to this method
When there are many 0#s in between, a specific pattern is detected from the codewords of the groups before and after, and the aPM method replaces it with a non-existent codeword pattern to limit the number of consecutive 0''s. .

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, the initial code conversion is performed using Table 1, but the correspondence between the eight types of data words and code words can be determined arbitrarily; the key is to set the correspondence on a one-to-one basis. That's fine. Then, the logical processing algorithm i1'11 may be changed according to the correspondence relationship. In other words, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a recording/reproducing apparatus to which the method of the present invention is applied, and FIG. 2 is a block diagram of an encoding apparatus. 1... Encoding device, 2... Decoding device, 12...
3-bit shift register, 16.22... 6-bit register, 15.17, 20.21... detector, 14.18, 1
9, 23, 24, 25, 26, 27.29... exclusive OR, 28... 6-bit shift register.

Claims (1)

[Claims] A binary data string is divided into 3-bit data words, and the 8 data words are (0, 0, 0, 0, 1°0).
, ((1,0,0,1,0,0) ,(0,1,0,
0,0,0), (0,1,0,0,1,0)(0,0
,1,0,0,0),(1,0,0,0,0,0),
(1,0,0,0,1,0). a first converting means for converting each data word obtained by dividing a Thfl binary data string into a code word in correspondence with a code word consisting of (1, 0, 0, 1, 0, 0); a second conversion means for converting (1, 0, 1) in the converted code word string to (0, 1, 0); 0), the 6th bit of the codeword in the previous group is (1), and the 1st and 2nd bits of the codeword in the later group are both (0), then (0,0 ,0,0,0,0)
is converted to (0,0,1,0,0°■), the converted codeword is (0,0,0,0,0,1), and the 6th bit of the codeword of the previous group is ( 0) at (0,0
, 0, 0, 0, 1) is converted to (0, 0, 1, 0, 0, 1), and the further converted code word is (0, 0, 0, 0° 1.0), which is the previous code word. When the codeword of a group is (1,0°0.0,0.0), the codeword of the previous group is changed to (1,0,0,0,0,1), and the above (0,0,0 ，
0, 1, 0) to (0°0.1, O, 0, 0), the binary data string is encoded, and the encoded data string is inverted according to the above correspondence relationship. An encoding/decoding method characterized by converting and decoding.