JPS5934750A - Method for encoding and decoding binary data - Google Patents

Abstract

PURPOSE:To attain the encoding where at least one ''0'' or two ''0s'' exist between a ''1'' and the next ''1'' in a 5-bit data train obtained through the conversion, by referencing data within 2-bit before and after a 2-bit data. CONSTITUTION:A data and a clock from terminals 2, 3 are inputted to a shift register and converted in parallel. A programmable logic array 4 performs the conversion of Q1=(-I3)+I3X(-I4)X(-5)XI6)X (-I7), Q2=I3XI4XI3X(-I4)X [I6+(-I5)+(-I6)], Q3=(-I3)X(-I4)+I3X (-I4)X(-I5)XI6+I1X(-I2)X(-I3)X I4, Q4=I3XI4+(-I3)XI4X(-I1)X(-I2)+I2, Q5=[I5+(-I5)X(-I6)]X[(-I4)+I1X (-I2)X(-I3)XI4]. A shift register 5 outputs a data to an FF6 in the clock being 5/2 times the original clock and a 5-bit data is obtained from a terminal 9. Thus, the ratio of the maximum magnetization inverting interval to minimum one is decreased as small as 1.5.

Description

DETAILED DESCRIPTION OF THE INVENTION When binary data is recorded on a recording medium such as a magnetic tape or a magnetic disk, or when reproduced from a recording medium, an original binary data string is suitable for recording. The encoding method (hereinafter referred to as the decoding method) for converting the converted 2 brigadier general code sequences into 1 side - r 2 4 i - I%I
It is something to do.

Conventionally, various encoding methods have been proposed and put into practical use when converting binary data to a recording medium such as a magnetic tape or a magnetic disk.

FIG. 1 is an explanatory diagram of an example of the conventional encoding method and the present invention. In the diagram, (5) is an example of the bit pattern of the original binary data string, and
An example of encoding using the IASE MARKl) method is shown. In addition, (q is the N RZ I signal waveform of the FM system, and this signal normally becomes the recording current waveform in the magnetic head.
This is an example of encoding using the dFM method.
pJi (z i waveform) of the signal. (F) is an example of encoding using the encoding method of the present invention, which will be explained later, and β) is the NRZ 1 waveform similarly according to the encoding method of the present invention. .

Now, in each method, when the pitch interval of the original data (A) is -ro, the maximum magnetization reversal interval of method 1 (
(hereinafter referred to as Tl1l a x), minimum sulfidation inversion interval (
FIG. 2 shows the wind mask margin of the above method, that is, the decoding phase margin during decoding (hereinafter referred to as T'w), and the number of patterns of magnetization reversal intervals. These parameters represent some of the capabilities in magnetic recording. ′ That is, if ′l′ m i n is small, it must be 11′
The A frequency band increases and the reproduction S/N ratio deteriorates. or,
When 'l' w is small, the phase margin during demodulation becomes small. Furthermore, if the Tmax/Tm1x ratio is large, the necessary recording and playback bands will increase, the ability to create a demodulation clock from the playback signal will be reduced, and waveform interference of +IG raw waveform will increase. Such adverse effects may occur.

This invention was made in consideration of W1 point among the conventional ones as mentioned above, and the T+nax/'I"min ratio is 1.
5, it is possible to use a band of 17/λ〈2, which was previously unusable in the digital magnetic recording system, and the decoding phase margin is Q, 4'l'o, which is almost equal to the theoretical limit, making it possible to The purpose is to provide a binary data encoding method and decoding method that has two types of pattern lengths, makes it easy to extract a reproduced clock, has little waveform interference, and allows for extremely easy configuration of hardware. It is said that

Hereinafter, an encoding method and a decoding method according to an embodiment of the present invention will be explained with reference to the drawings.

First, the algorithm 14 of the encoding method of the present invention and an example of its hardware configuration will be explained with reference to FIGS. 4 and 5.

In the encoding system of the present invention, the encoding algorithm for separating the original data into 2-bit units and converting them into 5-bit codes follows the 51 conversion table below.

S1 conversion table However, A and D are four types of patterns composed of 2-bit data, for example, A-1'-(JOJ, H-410J).

C2 "11", D-101".

Moreover, X is the complement logic of the bit immediately before the code bit X in the converted 44 columns, and is as follows.

The hardware configuration is shown in Fig. 4, where the original data is input manually (terminal -T121.signal '3 (=)) and the clock (terminal is), signal (b)), or the shift register (3) is used to convert the parallel signal to 6a. P L A (P ro gr
a+n m a old c LogicArray) +4
1, it is converted to 5 bits ↑9° using Fuku's algorithm.

(J+=(Ia(-Iax14xlbx16)x170
g = 18X14+l8X14X (16 ten 6XIg)
Og=Igx14+I+x14x16xlG)-! l
Xl2X 8×I404=I8X14+1llXI4X
(IIX-2 +12)06 = (It, +16XI
C) X (It-1-1 + x-work 2 , 1/2 of the original clock (b)
The data is taken in at that timing, and the clock (C) is 5/2 times the original clock (d).
), encoded data (e) is obtained. Note +7)
, (81 is each clock input terminal, (9) is an output terminal for encoded data.

Next, regarding the method for decoding encoded data, the configuration of a specific example thereof is shown in FIG. 6, and a timing diagram of the waveform is shown in FIG.

In FIG. 6 ζ, (101 is the input terminal for encoded data (g), +Il+ is the clock (') input terminal. Decoding must be performed every 5 bits, and t+3
1 is a synchronizing circuit (115<r) (output skin type (h)) for the y). Data (g) is the EXOR gate (1
2a) is output as a parallel signal by the shift register 20+. (141 is a circuit that extracts a specific pattern (Kari ~
With this specific pattern to be extracted, a special synchronization code pattern may be inserted for each certain number of data (blocks) of the original data. For example, [01000.

When inserting the pattern 10001.00010J, the logic circuit (141 is 01=IIXI'2XI11X ended)
is obtained by outputting . In addition, a specific fixed pattern is inserted into each block of the original take, and this encoding method (2
It is also possible to extract a pattern encoded using the 15 to 10,000 formula (tentatively named R). On the other hand, ;15) is cleared by the 5-bit same TrJ + signal fh), and the 20 ts (f) is 1
/2 decoding clock (in) generation circuit, (1
(to) is an output terminal of decoded data, and (IJ is an output terminal of decoded clock).

In this decoding circuit, the original data based on rlo, O1l/
XOloo, l0IOY J (However, Y is 1 or O
), the input data (g
) (This decoding circuit recognizes that the 2nd and 4th bits of the 5-bit data each indicate frame data, and that the encoded code has 3 0's and 1 The decoding process focuses on the two points that it is possible and good for two consecutive occurrences of
In the case of 0, 1010'l'J, the output of the shift register +7! X+, Xh, Xs
and the 5-hit synchronization signal Q are all positive logic, that is, due to the pattern of the 5-hit data string stored in the shift register +', O1, the output Xs of the shift register (support) j,
Xe, Xs are all 1, and data other than encoded data is input, and inputs X1 to X8 and X6 to X'l of the logic circuit (141) are all CO?i,
/' When the 5 frequency divider circuit (IC) output Q1・Sゝゝ1'', the output 1 of the 4-man power AND gate (16a) is
Output of shift register (up to R gate (12b))
Add to 7 and r > x o rtage - (12a)
According to the human power data (g), that is, - is written in 5 H I T 9
Column 1- X0IO0, 1(l IQyJ O)J”@,
Add it to the second bit (therefore, change the data string of the above 5 hits to l"X110t), change it to l0IIYJ,
1/2 frequency divider circuit (D flip-flop triggered by 15+!17)! Above this, the second . And the 4th bit is the symbol data (1). Also, the above 5 data string frXOIO
0, 1 (For cases other than J10YJ, addition is not performed in the EX Op-gate (12+) and the Oλ gate (1, 2b), and the D flip-flop (171) adds the second and fourth bits of each 5-bit data. This means that the bits are extracted as decoded data n.

Here, considering the characteristics of the method of the present invention using y (Fig. 32), the decoding phase margin 1'w during decoding is 0.8 compared to other methods (T'w = 0.5 To). times (
'I-w=0.4TO), but Tmax is 1.2 times that of the FM method (1,2'l'o), l'mi
Similarly, n is 1.6 times that of the FM method, and within the required band (
"'"j,'m"a'x-T' T m'i'ff
1-) is 0.8 times that of the FM method, and 0 of the M FM method.
, very small at 4 times. /J: It's very small. Also, Tma
The x/Tm1n ratio is 1.5, which is very small compared to the other two methods.

Now, within this required band and 1 mouth) ax / 1'min
Regarding the fact that the ratio is 15 when it is less than 2, it has an impact on magnetic recording, and IcCIE.
Otsushichi (5th self; Head gap in Ezuke (GL and,
+iLl! The relationship between the recording θ lamp length (λ) will be explained with reference to FIG.

・Figure 3 shows the recording wavelength (
λ) and the reproduction output characteristics due to the shadow powder of the reproduction Rad gap (g).1. ing. The output of one student is 7J'z using the generally known relational expression % (1), and the output has the minimum value of the reproduced output at the point g/λ=n (n is a positive integer). In Figure 1,
Let the curve of 0<g/λ<1 be (11-1), and t <
g/λ multiplied by 2 (1-1-2), 2 multiplied by g/λ multiplied by 3 (11
-3), the playback output +1"jl'lE (H-1
), (H-2), and (1(-3) are similar to the shape curve shown in the figure.Now, in the conventional magnetic recording/reproducing system, the (H-1) is It could only be used in the axis of the characteristic.As a cool note, the above 1'max/'
The l'min ratio is greater than 2, so the kerf (1
1-2) If the above characteristics are used, there will be a minimum point in the required area. In addition, conventionally, the reproduction output characteristic (H-2) has an extremely thick output value (g/λ・,=L'
Since g/λ is large, the reproduction of each color is
Factors that reduce the playback output between RAD and This often caused problems in terms of S/N.However,
Recently, with the development of new recording/reproducing heads and media such as perpendicular magnetic recording systems, the reproduction output in the (IL2) or (H-3) band has increased, and the effective use of this band has become more important. It has become necessary to record records. However, if the band (it-2) is to be used, the frequency band is (2) (relative velocity between the head and the tape) and tj, and the ratio is less than 2 and lJ is tj. This means that f
max c<l/Tm1n.

(From min oc l / Tmax, Trna
The x/Tm1n ratio must be less than or equal to 2.

From the above explanation, the Tmax/Tm1n ratio (
= 1.5) satisfies the conditions for use in the above (H-2) band. Therefore, it is said that the CH-2) band in Figure 2 can be used in digital magnetic recording, which has been unusable until now. There is a great advantage in the rear, and for this reason, the amount of information that can be recorded will be increased to dog 11J. Furthermore, there are two types of patterns in which magnetization reversal occurs, and there is an advantage that there is little mutual interference between the patterns.

Next, we will discuss how this method is extremely effective from five points from another information-theoretic perspective.

rained No1seless (:hann
el j by D,'1'','rang(1nf
Ormation and Control, 1
7,436-461 (1970)), in this method, d-1゜k=2 (however, d is the number of "O" bits between encoded "1" bits). Minimum and maximum 1
code phase margin '1' in the encoding method
The theoretical limit of w is 0.405'7 To (To is the bit interval of the original data). The ding W of the Honwa coding system is 0.
．． It is 4TO, which is 0.99 times the theoretical value limit, which is 1 shift, and in terms of information theory, it is almost the same as the 9° encoding method, which is close to μP.

As explained in Section 2 below, the encoding method of the present invention is T'n
i a x / ]−min ratio is 15, and fi
il' = Self-discipline 1' - The band of 1<g/l<2, which was previously unusable in the liquid recording system, can be used, and the decoding phase margin is Q, and jJ is equal to the theoretical limit of 41'o. There are two types of pattern lengths that are generated, the reproduction clock can be easily extracted, and the encoding method has less waveform interference. In addition, the hardware 1-square configuration is very simple and has great self-help properties.

[Brief explanation of the drawing]

11th:? 4j is a diagram showing encoding examples of the conventional and present invention encoding methods, FIG. 2 is a parameter diagram showing the capabilities of the conventional and present invention encoding methods, and FIG. 3 is a diagram showing reproduction gap length (g ) and a reproduction blade characteristic diagram due to the influence of the recording wavelength (λ), and FIG. 4 shows one embodiment of the encoding circuit of the present invention. Figure 5 is a time chart of the explanatory waveforms in Figure 4, No. 61 Zo 1 is a circuit diagram of a specific IqI of the decoding circuit according to the present invention, and No. 7 is a circuit diagram of the decoding circuit according to the present invention.
The figure is a time chart diagram of the explanatory waveform of FIG. 6. +1), 12) +(7), (8)...signal input terminal, (9)...100 output terminal, 13), 15)
...Shift register, :4)...t' 1-A
(Programmable e Logic Arra
y), 16)...l) 7 lipflop, (10
), tl+)...Shingo input terminal F, 1181,
Hit...1 Hatake output terminal, 12...Decoding circuit, 12
tll...shift register, (+71, f21)
...I) Flip-flop, +15), 113)
... Branch circuit, (16) ... 4-person AND circuit, (
14)...Logic circuit for synchronization detection, a...Input signal (
2-bit data), e...Encoded data (5-bit data), g...Encoded data (5-bit data), ■
]...Decoded data (2-bit data). Agent Tsutomu Kuzuno - Figure 3% Figure 4 Figure 5 (1) e

Claims (1)

[Scope of Claims] (1) An encoding method that divides a binary data string into every 2 bits and converts each of the divided 2-bit data into 5-bit data, in which the 3 to 2 bits to be encoded are Theta's +jiJ after 2 hits or more 1.
One bit 1 in the 5-bit data string obtained by conversion and the next bit 1 in the 5-bit data string 1fji l bit 0/J) Encode so that there is always one or two bits. A method of encoding binary data, characterized in that: A method for encoding binary data according to claim 1, characterized in that the conversion is performed using the following 51 conversion table during +21 J-code encoding. S1 conversion table where A and D are four different bit patterns consisting of 2 bits, X is the complement logic of the bit immediately before the code bit x in the converted code string, (3) A decoding method for decoding a binary data string consisting of 2-bit data from a data string encoded using the following sl < conversion table, in which the bit immediately before the 5-bit Inverted logic of , Y is 1 or 0), if it is continuous,
10, 01'', and except for consecutive cases as indicated by -, the 2nd bit data and the 4th bit data of the 5 bit data are made into 2 bit data. How to decrypt. S1 Variable Table However, A and D are four different bit patterns X each consisting of 2 bits, and are the complement logic of the bit immediately before the code bit l-X in the converted code string.