KR20090012422A - Method and apparatus of modulating data, and method and apparatus for recording data - Google Patents

Abstract

A data modulating method and apparatus, and a recording method and apparatus are provided to perform stable recording and/or reproduction of data by replacing a part of channel sequence with a subsidiary sequence when the generated channel sequence violates the RMTR limit. A data modulating method comprises a step of producing a channel sequence by using a first table including a code word corresponding to input data(10) and information designating the next state, and a step of replacing a part of channel sequence with a subsidiary sequence when the generated channel sequence violates the RMTR(Repeated Minimum Transition Run-length) limit, where the subsidiary sequence cannot be generated from the first table.

Description

Data modulation method, modulation device, recording method and recording device {Method and apparatus of modulating data, and method and apparatus for recording data}

The present invention provides a data modulation method and a modulation device. The present invention relates to a recording method and a recording apparatus, and more particularly, to a method, an apparatus, and a recording method and apparatus for modulating data recorded on an optical recording medium or data reproduced from an optical recording medium.

Recording media for recording information such as video and audio information are produced in the form of discs with fast random access. Data recorded on such a disk is modulated and recorded in a code sequence suitable for a recording medium. In this case, a modulation scheme for generating a code sequence has a high code conversion efficiency, a stable playback clock, and a jitter margin for securing stable data. In addition, the modulation scheme needs to generate a code sequence capable of stabilizing the operation of a servo system such as a tracking servo when recording digital signals and stabilizing a reproduction clock during reproduction.

It is an object of the present invention to provide a data modulation method capable of stable data recording and reproduction.

Another object of the present invention is to provide a modulation method having high code conversion efficiency and stabilizing the operation of a servo system.

Another object of the present invention is to provide a modulation code having a low repeated minimum transition run-length (RMTR).

In order to achieve the above object, a data modulation method according to the present invention comprises generating a channel sequence using a first table including a codeword corresponding to input data and information specifying a next state, and a generated channel sequence. If a violation of the Repeated Minimum Transition Run-length (RMTR) restriction occurs, replacing at least a portion of the channel sequence with an auxiliary sequence included in the second table.

The auxiliary sequence may be a sequence that cannot be generated by the first table. At this time, the RMTR restriction may be four.

In this case, a code having a minimum run length of 1 and a maximum run length of 7 may be generated. It is also possible to generate code with a minimum run length of 1 and a maximum run length of 11.

The first table includes four levels of states, and each state can designate a three-bit codeword corresponding to two bits of input data.

Meanwhile, the data modulation apparatus according to the present invention includes a first table including a codeword corresponding to input data and information specifying a next state, and an auxiliary sequence for limiting the RMTR of the channel sequence generated by the first table. It includes a second table.

On the other hand, the data recording method according to the present invention comprises the steps of generating a channel sequence using a first table including a codeword corresponding to the input data and information specifying the next state, the generated channel sequence violates the RMTR restriction In this case, the method includes replacing the at least part of the channel sequence with an auxiliary sequence to generate modulated data and storing the modulated data on the recording medium.

On the other hand, the data recording apparatus according to the present invention includes a modulation unit for generating modulation data for the input data and a recording unit for storing the modulation data generated by the modulation unit on a recording medium, the modulation unit and the code word corresponding to the input data; A first table includes information specifying a next state, and a second table including an auxiliary sequence for RMTR restriction of a channel sequence generated by the first table.

The present invention provides a data modulation method that can stably record and / or reproduce data. In addition, the present invention provides a modulation method having high code conversion efficiency and stabilizing the operation of the servo system. In addition, it is possible to provide a modulation code having low RMTR and excellent DC suppression efficiency.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of a data modulation method and a recording and reproducing apparatus according to the present invention as described above will be described in detail. The term " recording / reproducing device " means any device capable of recording data or reproducing recorded data using a recording medium. The term " recording medium " means any medium in which data is recorded or can be recorded, and specifically, an optical disk can be given. In addition, the terminology used in the present invention was selected as a general term that is widely used at present, but in some cases, the term is arbitrarily selected by the applicant, and in this case, since the meaning is described in detail in the corresponding part of the present invention, a simple term is used. It is to be understood that the present invention is understood as a meaning of terms rather than names.

An embodiment of a data modulation method according to the present invention will be described in detail with reference to the drawings. In the present specification, a case consisting of four registers is described as an example for convenience of description, but the present invention is not limited to the present embodiment.

The modulation device 100 included in the recording apparatus according to the embodiment of the present invention includes a modulator 12, a modulation table 14, and an NRZI converter 16, as shown in FIG.

The modulator 12 is a portion for generating a codeword by modulating the input data 10 corresponding to the modulation table 14 of the present invention. In this case, the modulation table 14 includes at least one register, and each register includes a first table and information indicating a next register and a codeword corresponding to the input data 10 and a repeated minimum transition (RMTR). A second table for limiting run-length) The configuration of the modulation table 14 will be described later.

The NRZI converter 16 converts the modulated codeword to NRZI and provides it to the recording unit 18. In this case, the NRZI conversion refers to a conversion operation for indicating that 0 written in binary according to input data has no change in the recording medium, and 1 written in binary indicates a transition in the opposite direction from the recording medium.

In this case, the modulator 100 may further include a control bit selector (not shown) for inserting control bits at predetermined intervals into the input data 10 according to the sum of the generated NRZI signals.

The codeword generated in the modulation device 100 generates a modulation code. The recording unit 18 such as the optical pickup records the modulation code on the recording medium 20.

Meanwhile, as shown in FIG. 2, the demodulation device 200 according to the embodiment of the present invention includes a readout unit 22, an equalizer 24, a PLL circuit 26, a demodulator 28, and a demodulation table ( 30). The reading unit 21 such as the optical pickup reads the codeword from the demodulation table 18 and provides it to the equalizing unit 24.

The equalizer 24 equalizes the codeword received from the reader 21 and provides it to the PLL circuit 26.

The PLL circuit 26 provides the received data to the demodulator 28, which converts the received codeword sequence into output data 26 with reference to the demodulation table 30. The demodulation table 30 is the same as using the above-described modulation table 14 in reverse, and the detailed description is replaced with the description regarding the structure of the modulation table 14 which will be described later.

A method of modulating data according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4 and Tables 1 to 3. For convenience of description, in the present specification, a case where a code rate is 2/3, that is, a codeword of 3 bits is generated for an input bit of 2 bits is used as an example. Listen and explain. In addition, although the modulation method in the case where the first table includes four registers each divided into four states is described as an example, the present invention is not limited thereto. Table 1 shows an example of the first table.

First, a specific example of a method of modulating data using the first table illustrated in Table 1 will be described with reference to FIG. 3.

Assume that the input data is [01 01 11 11] and the set initial value is state 1. Thus, as shown in Fig. 3, it starts from state 1 set to an initial value.

As shown in Table 1, when the input bit in state 1 is 01, the corresponding codeword is 010. Therefore, the output codeword is 010, and the next state is 2. When the input bit in state 2 is 01, the corresponding codeword is 101.

Therefore, the output codeword is 101, where the next specified value is state 4. When the input bit in state 4 is 11, the corresponding codeword is 000. Therefore, the output codeword is 000, and the next specified value is state 3. When the input bit in state 3 is 11, the corresponding codeword is 000. Therefore, the output codeword is 000, and the next designated value becomes state 2. The modulation code generated in this way is [010 101 000 000].

As described above, the modulation code generated by the first table has the following characteristics.

First, a modulation code generated using a modulation table is a run-length-limited (RLL) code. This is a code that limits the run length in the modulated code string, where run is the number of consecutive zeros between one and one.

In the RLL (d, k) code, d has a condition in which at least d zeros are added between consecutive data 1, and k must not exceed 0 between consecutive data 1 and 1. . Here, d, which limits the minimum run length, is for removing interference between symbols generated by a group of pulses to be reproduced when a series of 1 data is continuously recorded. And k, which limits the maximum run length, is for recovering the clock from the reproduction data by locking a phase lock lop (PLL) to the transition of the reproduction signal. If the string of consecutive zeros is too long, the clock reproduction PLL is out of sync.

The modulation code generated in this embodiment is an RLL (1,7) code. That is, the number of consecutive zeros between 1 and 1 is at least 1 and at most 7 is always established. For example, as described above, a modulation code of [010 101 000 000] is generated for the input data of [10 11 00 01], and the number of consecutive zeros between 1 and 1 in the modulation code is 1 and 7 is maximum. It becomes a dog. The first table is generated to establish such a rule, and the first table has the following characteristics.

As shown in Fig. 4, four registers composed of state 1 to state 4 output a codeword corresponding to the input data and designate the next state. At this time, each state is configured to designate the next state in consideration of the generated codeword.

For example, if the codeword generated next when generating a modulation code of [010 101 000 000] with respect to the input data of [01 01 11 11] is 00x, the number of consecutive zeros is 8 or more. The maximum run length limit is violated. At this time, the last state 2 specified does not include 00x in the generated codeword.

As another example, if the initial value is state 4 and the input bit is [11 00], a codeword is generated as follows. That is, in state 4 of Table 1, when the input bit is 11, the corresponding codeword is 000. Therefore, the output codeword is 000, and the next designated value is state 3. In state 3 of Table 1, when the input bit is 00, the corresponding codeword is 000. Therefore, the output codeword is 000, and the next designated value is state 1. State 1 specified here does not generate a codeword of 00x. Therefore, the maximum run length limit is not exceeded.

The modulation table thus generated designates the next state as shown in FIG. That is, state 1 designates different states according to the input data, but does not designate state 4 as the next state.

State 4 also specifies different states depending on the input data, but does not designate state 4 as the next state. This is because, when state 1 outputs 100, specifying state 4 may violate the maximum run length limit.

Also, if the end of the generated codeword is 1, the next state specifies state 3 or state 4 that does not begin with 1.

In addition, the transform table may generate the same codeword for different input data. For example, in the state 1 of Table 1, the codeword of 010 is output in the same manner as in the case where the input data is 01 and 10. However, even in this case, different input data can be distinguished by differently designating the next state as 1 or 2.

Second, codewords specified in each state of the modulation table are interchangeable. That is, in the same state, even if three-bit codewords corresponding to two-bit input data are interchanged, the RLL (1,7) rule is established. However, the next state specified by the generated codeword cannot be changed.

For example, unlike Table 1, in the state 1, 100 may be output when the input data is 00, and 010 may be output when the input data is 11. However, even in this case, when the generated codeword is 010, the next state specifies 1. When the generated codeword is 100, the next state specifies 3. In other words, when the codeword for the input data is changed, the next state is also changed. Even in this case, the same rule holds.

Accordingly, the first table may generate different modulation codes by designating different codewords for input data within each state.

Meanwhile, in Table 1, codewords of 010 and 101 may be repeatedly generated. For example, if the input data is [01 01 01] and the initial state is 4, the channel sequence generated in Table 1 is [010 101 010 101]. In other words, the pattern of 2T is repeated continuously. In this case, the Repeated Minimum Transition Run-length (RMTR) according to the first table becomes infinite.

Thus, in such a case, the RMTR is limited by the second table that replaces a part of the channel sequence generated by the first table.

Table 2 shows an example of the 2nd table which designs 2/3 (1, 11, 4), and Table 3 shows an example of the 2nd table which designs 2/3 (1, 7, 4).

In this case, the channel sequence generated to limit the RMTR in the channel sequence generated in the first table may be replaced with a sequence that cannot be generated in the first table. As a result, the codes having the small RMTR presented in the present invention are only a part, and by adding the replacement tables as shown in Tables 2 and 3 based on the first table, the modulation codes having a small RMTR and excellent DC suppression side can be obtained. Can design

The data modulation method according to an embodiment of the present invention generates a modulation code controlled by a DC component by using the first and second tables. When a DC component is included in the modulated code sequence, various error signals such as tracking errors generated in the servo control of the disk driver are biased or jitter easily occurs. Therefore, it is necessary to use a signal having no DC component so that continuous tracking control is not disturbed by signal recording.

As a method for preventing the DC component from being included in the modulated sequence, a DSV (Digital Sum Value, hereinafter referred to as "DSV") or RDS (Running Digital Sum, hereinafter referred to as "RDS") control method may be used. This is an indicator indicating the DC component included in the sequence string, and controls the DC component by inserting a control bit, for example, a parity bit, into the input data at regular intervals.

1 is a block diagram of a modulation device according to an embodiment of the present invention.

2 is a block diagram of a demodulation device according to an embodiment of the present invention.

3 is a block diagram illustrating an example of a process of generating a modulation code according to a modulation table.

4 is a block diagram showing next state designation according to a modulation table.

* Description of the symbols for the main parts of the drawings *

10: input data 12: modulator

14: modulation table 16: NRZI converter

18: recording unit 20: recording medium

22: reader 24: equalizer

26: PLL circuit 28: demodulator

30: demodulation table 32: output data

100: modulation device 200: demodulation device

Claims (14)

Generating a channel sequence using a first table comprising a codeword corresponding to the input data and information specifying the next state; And If the generated channel sequence violates a Repeated Minimum Transition Run-length (RMTR) restriction, replacing at least a portion of the channel sequence with an auxiliary sequence Modulation method of the data comprising a. According to claim 1, And said auxiliary sequence is a sequence that cannot be generated by said first table. The method of claim 2, And the RMTR restriction is 4 in the substituting with the auxiliary sequence. The method of claim 3, wherein A modulation method of data for generating a code having a minimum run length of 1 and a maximum run length of 7. The method of claim 3, wherein A modulation method of data generating a code having a minimum run length of 1 and a maximum run length of 11. According to claim 1, And said first table comprises four levels of states, each state designating a three-bit codeword corresponding to two bits of input data. A first table comprising codewords corresponding to the input data and information designating the next state; And A second table including an auxiliary sequence for RMTR restriction of a channel sequence generated by the first table Modulator for data comprising a. According to claim 1, And the auxiliary sequence is a sequence that cannot be generated by the first table. The method of claim 8, And a data modulation device of which the RMTR limit is four. The method of claim 9, A modulator for data generating a code having a minimum run length of 1 and a maximum run length of 7. The method of claim 9, A modulator of data generating a code having a minimum run length of 1 and a maximum run length of 11. The method of claim 7, wherein And said first table comprises four levels of states, each state designating a three-bit codeword corresponding to two bits of input data. Generating a channel sequence using a first table comprising a codeword corresponding to the input data and information specifying the next state; If the generated channel sequence violates the RMTR restriction, generating modulated data by replacing at least a portion of the channel sequence with an auxiliary sequence; And Storing the modulated data on a recording medium Data recording method comprising a. A modulator for generating modulated data for the input data; And A recording unit for storing the modulation data generated by the modulation unit on a recording medium Including, The modulator may include a first table including a codeword corresponding to input data and information designating a next state; And A second table including an auxiliary sequence for RMTR restriction of a channel sequence generated by the first table Data recording device comprising a.

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