JPH05258474A - Coder/decoder - Google Patents

Abstract

PURPOSE:To provide the coder/decoder requiring a minimum amount of redundancy to complete the modulation/demodulation without missing information in the fixed-length block. CONSTITUTION:Recording data is supplied to a timing circuit 5 and given to ROM 1 comprising the first conversion table and to ROM 2 comprising the second conversion table. When the timing circuit 5 detects the block boundary of recording data, the first conversion table switches the output from the first sign string to the output from the second sign string.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding device and a decoding device suitable for use in digitally recording and reproducing data on a recording medium.

[0002]

2. Description of the Related Art In a magnetic recording / reproducing system, for example, the frequency characteristic of a signal is generally a differential characteristic, and there is deterioration in a high frequency range. This is due to, for example, a loss due to a head gap, a loss due to a space between head media, a loss due to a medium thickness, and a low frequency loss due to a rotary transformer. Further, noise such as crosstalk noise from adjacent tracks, noise from the medium, and overwrite noise will cause random errors. In order to accurately record / reproduce data regardless of such loss or noise, digital information is encoded and recorded on a recording medium so as to be compatible with the recording / reproducing system, and the reproduced data from the recording medium is decoded. More information can be stored in a more stable manner. For this reason,
Data (recording signal) is converted into a recording code (channel code) according to a predetermined rule.

Among such recording codes is a block code. This block code is to block a data string into m × i bits each and convert this data word into a recording code of n × i channel bits according to a predetermined code rule. When i = 1, it becomes a fixed length code, and when i is larger than 1 and the constraint length r is larger than 1, it becomes a variable length code. The block code is also called a (d, k; m, n; r) code. Here, d shows the minimum continuous number of 0, and k shows the maximum continuous number of 0.

[0004]

By the way, for example, considering a variable length code (4, 22; 2, 5; 5) as an example,
As shown in FIG. 4, there are five types of variable length codes having conversion input data lengths of 2, 4, 6, 8 and 10 bits. In addition, there are 10 ways to extend the block length as shown in FIG. In FIG. 6, a vertical line k at the center indicates a block boundary. In this situation, if the demodulation is attempted to be completed only within the block, that is, in FIG.
If demodulation is attempted only with the shaded area, it may be impossible to demodulate or an error may occur in the demodulation result unless the modulation code is devised. Also, when modulation is performed over two blocks, when a sudden block demodulation is attempted, the code of the previous block does not exist,
It may be impossible to demodulate.

FIG. 7 shows an example of the case where the demodulation cannot be performed or an error occurs in the demodulation result. That is, when encoding and decoding are performed across the block boundary as shown in FIG. 6, first, for the recording data shown in (A), the code existing in the left column of FIG. Based on this, the code is converted into the code shown in the right column. In this case, according to FIG.
11 ”is“ 0100000010 ”as shown in the right column.
It is encoded into a variable length code as "0000100000". This state is shown in FIG. 7B. When the variable length code is to be decoded, the code of "0100000010" in the block is However, the code in this case is not applicable in the table shown in Fig. 4 and cannot be demodulated (decoded) as shown in Fig. 7C. The outside "0000100000" is decoded as "0100" according to the table shown in FIG. 4, but as a result, this becomes different from the input data, that is, the recording data.

The present invention has been made in view of such a point, and in a variable length modulation code, there is no loss of information in a fixed length block, and modulation / demodulation is completed with minimum necessary redundancy. An object of the present invention is to provide an encoding device and a decoding device capable of performing the above.

[0007]

The encoding device according to claim 1 of the present invention, which has been made to achieve the above object, uses a record data as an input, and manages a timing for detecting a boundary between blocks of the record data. Input means and recorded data,
First converting means for converting the input record data into a first code string according to a first conversion table, and inputting the record data,
Second conversion means for converting the input record data into a second code string according to the second conversion table, a first code string converted by the first conversion means, and a second code string converted by the second conversion means are supplied. When the timing management means detects a block boundary of the recording data, the first means is provided to the multiplexing means.
From the first code string by the conversion means to the second by the second conversion means
It is characterized in that a control signal for switching the output to the code string is transmitted.

A decoding device according to a second aspect of the present invention has a variable length code as an input, a timing management means for detecting a specific code string in the variable length code, and a variable length code as an input, and an input variable. First conversion means for converting a long code into first demodulated data according to a first conversion table and second conversion means for inputting a variable length code and converting the input variable length code into second demodulated data according to a second conversion table. Means and first
The first demodulated data and the second converted by the conversion means
Second multiplexing means for supplying the second demodulated data converted by the converting means, when the timing managing means detects a specific code string in the variable length code, the second converting means is provided to the multiplex means. It is characterized in that a control signal for switching the output from the second demodulated data by the above to the first demodulated data by the first conversion means is sent.

[0009]

In the encoding device according to the first aspect of the present invention, the recorded data is first recorded by the first and second conversion means.
Conversion table and second conversion table according to the first
It is converted into a code string and a second code string and supplied to the multiplex means. Then, when the timing management means detects the boundary of the block of the recording data, the timing management means supplies a control signal to the multiplex means, and outputs the multiplex means from the first code string by the first conversion means. It is configured to switch to the second code string by the two conversion means. By such an action, the record data can be converted into a variable length code which completes the modulation with the minimum required redundancy.

Further, in the decoding device according to the second aspect, the variable length code is converted by the first and second conversion means into the first conversion table and the second conversion table, respectively, and accordingly the first demodulated data and the second demodulated data. It is converted into demodulated data and supplied to the multiplex means. When the timing management means detects a specific code string in the variable length code, the timing management means supplies a control signal to the multiplex means, and the output from the multiplex means is used as the second demodulated data by the second conversion means. To the first demodulated data by the first conversion means.
By such an action, demodulated data without loss of information can be obtained.

[0011]

The present invention will be described below with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of an encoding apparatus of the present invention. In this embodiment, the record data is supplied to the ROM 1 as the first conversion means and the ROM 2 as the second conversion means, and the table 1 constituting the first conversion table stored therein.
The recording data is encoded according to Table 2 which constitutes the second conversion table. ROM
1 and the code string output from the ROM 2 are supplied to a multiplexer (MUX) 3 as a multiplexing means.

The output of the MUX3 is configured to be supplied to the MUX4, and a synchronization signal (SYNC) is supplied to the MUX4 from a circuit (not shown). Further, the recording data is also supplied to a timing circuit 5 which constitutes a timing management means, and the timing circuit 5 monitors the recording data and detects a block boundary (k) of the recording data. When the timing circuit 5 detects a block boundary of the recording data, the timing circuit 5
A control signal is sent to the MUX 3 so that the MUX 3 switches the output from the first code string converted by the ROM 1 to the second code string converted by the ROM 2. When the timing circuit 5 detects a block boundary of the recording data, the timing circuit 5 causes the MUX 4 to
To the control signal.

The ROM 1 has a table 1 shown in FIG.
Is remembered. That is, this table 1 shows the recording data of 2 bits, 4 bits, 6 bits, 8 bits or 10 bits shown on the left side of FIG. 4 and the recording data of 5 bits, 10 bits, 15 bits, 20 bits or 25 bits shown on the right side thereof. Convert to recording code. Further, the ROM 2 stores a table 2 shown in FIG. That is, this table 2 has 2 bits, 4 bits shown on the left side of FIG.
The 6-bit or 8-bit recording data is converted to the 5-bit, 10-bit, 15-bit or 20-bit recording code shown on the right side thereof.

Table 1 shown in FIG. 4 is for converting print data that fits within a block boundary as a unit for processing print data, while table 2 shown in FIG. 5 is for processing print data. The print data is converted when a block as a unit of is written.

In the above structure, the timing circuit 5 in FIG. 1 monitors the supplied recording data and manages the timing. If the recorded data is contained in the block, the modulated data converted according to the conversion rule of the table 1 stored in the ROM 1, that is, the encoded data is selected and output.

Here, the recording data is, for example, "000".
When 10111 ″ arrives and the timing circuit 5 determines that the 4-bit portion becomes a block boundary, the timing circuit 5 sends a control signal to the MUX 3, and the 4-bit data in the block, that is, “ 000
For "1", data "010000100" converted according to the conversion rule of table 2 stored in ROM2
0 ". The remaining 4 bits," 011 "
The data of "1" is converted into the code string of "0100000000" according to the conversion rule of the table 1 stored in the ROM1.

FIG. 3 illustrates the operation at this time, where (A) shows recording data and (B) shows converted encoded data. Therefore, the recording data “00010101” that extends over the block boundary in 4 bits
As a result, "1" is "01000010010001000".
It is converted into a code string of "00000". At this time, a synchronization signal (SYNC) indicating a break of a block is inserted via the MUX 4 as needed.

Next, FIG. 2 is a block diagram showing the configuration of an embodiment of the decoding apparatus of the present invention. In this embodiment, the reproduction data, that is, the variable length code is supplied to the ROM 11 as the first conversion means and the ROM 12 as the second conversion means, and the table 1 and the table 1 constituting the first conversion table stored therein are stored. Playback data is decoded in accordance with Table 2 which constitutes the second conversion table. ROM11 and ROM1
The first and second demodulated data output from 2 are supplied to the MUX 13 as a multiplexing means.

On the other hand, the reproduced data is the sync signal detection circuit 14
And a timing circuit 15 as timing management means
The timing circuit 15 monitors the output of the sync signal detection circuit 14 and the reproduction data, and when a specific code string is detected in the reproduction data, the timing circuit 15 sends a control signal to the MUX 13. Send out.
The MUX 13, which has received the control signal, is stored in the ROM 12
The output is switched from the second demodulated data converted by the above to the first demodulated data converted by the ROM 11. In other words, if the timing circuit 15 does not detect a specific code string in the reproduction data, the ROM 1
The second demodulated data converted by 2 is output.

That is, as shown in FIG. 4, the last 5 characters of the data converted by the ROM 1 are all "0000".
In contrast to 0 ", as shown in FIG. 5, the last 5 characters of the data converted by the ROM 2 are" 00000 ".
It's not. Therefore, the last 5 characters are "0000"
It can be identified by which table the data is converted depending on whether or not it is "0".

The ROM 11 and the ROM 12 constitute an inverse conversion circuit of the tables stored in the above-mentioned ROM 1 and ROM 2 (a circuit for converting the code on the right side of FIGS. 4 and 5 into the code on the left side).

FIGS. 3 (B) and 3 (C) explain the conversion action at this time. That is, (B) of FIG.
The reproduction data shown as is detected by the timing circuit 15, and the timing circuit 15 determines the end of the block with "00000" which is a specific code string (whether the end of the block is the next synchronization signal or not). (Determinable) data is completed. As shown in FIG. 3B, the last reproduced data of the block is “0100001000”, and therefore the reproduced data is decoded as demodulated data by the second conversion means in the ROM 12, and the decoded data of “0001” is can get.

Further, the reproduction data at the head of the next block (head excluding the sync signal) is "0100000000", and at this time, the timing circuit indicates that the data ends at "00000" which is a specific code string. Detected at 15. Therefore, the reproduced data at this time is decoded as demodulated data by the first conversion means in the ROM 11, and decoded data of "0111" is obtained.

[0024]

As is apparent from the above description, claim 1
According to the encoding device described in (1), when the timing management means detects the boundary of the block of the recording data, the timing management means supplies a control signal to the multiplex means, and the first code by the first conversion table. The output is switched from the column to the second code sequence according to the second conversion table. Therefore, it is possible to convert the recorded data into a variable-length code whose modulation is completed with the minimum required redundancy.

Further, according to the decoding device of the second aspect, when the timing management means detects a specific code string in the variable length code, the timing management means supplies a control signal to the multiplexing means. , The output is switched from the second demodulated data by the second conversion table to the first demodulated data by the first conversion table. Therefore, it is possible to obtain decoded data without information loss or demodulation error.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an encoding device of the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of a decoding device of the present invention.

FIG. 3 is a conceptual diagram showing an example in which data is normally demodulated in a decoding process.

FIG. 4 is a ROM1 and a ROM in FIGS. 1 and 2;
It is a figure explaining the content of the table memorize | stored in FIG.

FIG. 5 is a ROM 2 and a ROM in FIGS. 1 and 2;
12 is a diagram illustrating the contents of the table stored in FIG.

FIG. 6 is a conceptual diagram showing a relationship between a conversion input data length and a block length.

FIG. 7 is a conceptual diagram showing an example of a case where data cannot be demodulated or an error occurs in the decoding process.

[Explanation of symbols]

 1 ROM (1st conversion table) 2 ROM (2nd conversion table) 3,4 Multiplexer (multiplex means) 5 Timing circuit (timing management means) 11 ROM (1st reverse conversion table) 12 ROM (2nd reverse conversion table) ) 13 multiplexer (multiplex means) 14 synchronization detection circuit 15 timing circuit (timing management means)

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshiyuki Nakagawa 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (2)

[Claims] 1. An encoding device for encoding recording data into a variable-length code, wherein the recording data is input, timing management means for detecting a boundary of a block of the recording data, and the recording data is input, and input recording is performed. First conversion means for converting data into a first code string according to a first conversion table; and second conversion means for inputting the recording data and converting input recording data into a second code string according to a second conversion table. A multiplex means to which the first code sequence converted by the first conversion means and the second code sequence converted by the second conversion means are supplied, and the timing management means controls the block of the recording data. When a boundary is detected, an output is switched from the first code string by the first converting means to the second code string by the second converting means for the multiplexing means. Encoding apparatus characterized by being adapted to deliver the changing control signal. 2. A decoding device for decoding a variable-length code, wherein the variable-length code is input, timing management means for detecting a specific code string in the variable-length code, and the variable-length code is input. First conversion means for converting a variable length code into first demodulation data according to a first conversion table; and a first conversion means for converting the input variable length code into second demodulation data according to a second conversion table. 2 conversion means and multiplex means to which the first demodulated data converted by the first conversion means and the second demodulated data converted by the second conversion means are supplied, and the timing management means is variable. When a specific code string in the long code is detected, the first demodulating means converts the second demodulated data by the second converting means into the first means by the first converting means. Decoding apparatus characterized by the tone data so as to deliver a control signal for switching the output.