KR20030083041A - Method for demodulating wobble signal on optical disc - Google Patents

Abstract

PURPOSE: A wobble signal demodulating method for an optical disc is provided to generate physical address information of ADIP words with reference to packet data of ADIP units and precisely generate pseudo packet data corresponding to packet data to generate, thereby carrying out the demodulating operation of wobble signals by a simple hardware and algorithm in a short time. CONSTITUTION: A wobble signal demodulating method for an optical disc includes the steps of initiating a bit clock count value output from a clock detector to zero(S30), and checking a bit clock output from the clock detector(S31). A level of a peak detecting signal output from a peak detector is checked when the bit clock transits from a high level to a low level. The bit detector outputs a data bit of '0' or '1' according to the level of the bit clock and such output data bits are temporarily stored in an address decoder in sequence(S32). The bit detector accumulates and increases the count value of the bit clock by one(S33). When the count value of the bit clock reaches '56', the data bits are compared with preset 8 ADIP units(S34). As an equal ADIP unit is detected, a packet data corresponding to the detected ADIP unit is stored in sequence(S35). Otherwise, it is regarded as a detection error of wobble signals caused by defects of an optical disc, so that a current packet data position is checked(S36) and a pseudo packet data is generated correspondingly(S37). The address decoder temporarily stores such generated 83 packet data in sequence(S38) and ADIP words are generated with reference to the packet data(S39).

Description

Demodulation method of optical disc wobble signal {Method for demodulating wobble signal on optical disc}

The present invention relates to an optical disc wobble signal demodulating method for demodulating a wobble signal recorded as physical address information on an optical disc such as a recordable CD (CD) or a DVD (DVD).

In general, a recordable optical disc, for example, an optical disc such as a DVD-RAM or a DVD-RW (Re-Writable), has a recording surface of an optical disc for controlling a spindle servo operation or providing a clock for recording and reproducing data. Physical address information must be recorded in advance on the screen. A wobble addressing method for recording the physical address information as a wobble signal on an optical disc will now be described.

First, the wobble addressing method using the Complementary Allocated Pit Addressing (CAPA) method is used in the case of the DVD-RAM, and the wobble addressing method using the Land Pre-Pit Addressing method in the case of the DVD-RW. A method and the like have been used. In recent years, a wobble addressing method using a minimum shift keying (MSK) modulation method has been proposed.

On the other hand, in the MSK modulation scheme, a block diagram, the in-phase messages from a wobble data to be recorded as a physical address information on the optical disc, as shown in _{1 (m I: Inphase messageof wobble} data) and quadrature phase messages (m _Q: Quadrature message By the combination of the wobble data, two different frequencies (f ₁ , f ₂ ) and two phases (P ₁ , P ₂ ), respectively, are determined, and by the two different frequencies and two phases, 4 To generate wobble signals of two different waveforms, wherein the two different frequencies, for example, the first frequency f ₁ , have a frequency value higher than the center frequency fc and the second frequency f. ₂ ) has a frequency value lower than the center frequency f _c ,

The two different phases, for example, the first phase P ₁ have a zero phase, and the second phase P ₂ has a 180 degree phase π. As described above, four different waveforms generated according to the first and second frequencies and the first and second phases, that is, , , , And The MSK wobble signal having? Is expressed by the following equation.

-Formula (1)

Here, T _b represents the wobble data bit duration. For example, as shown in FIG. 2, when the wobble data to be recorded on the optical disc is bit string data of '11010000', the in-phase the combination of the message (m _I) and quadrature phase messages (m _Q) is always so should be (m _I, m _Q), (m _I, m _Q) of the first bit '1', the second bit ' Combination with 1 'results in (1,1), and ( m _I , m _Q ) for the second bit' 1 'becomes (0,1) in combination with the third bit' 0 '. .

Since ( m _I , m _Q ) for the third bit '0' becomes (1,0) by combination with the fourth bit '1', eventually ( m _I , m _Q ) becomes (1 , 1), (1,0), (0,1), (0,0), and the pulse signal corresponding thereto is different from two different frequencies as shown in FIG. You will have four different waveforms with two phases.

Therefore, the MSK wobble signal S _MSK (t) has a smoothly continuous pulse waveform by summing the pulse signals, so that the wobble signal can be recorded more accurately on the optical disc.

On the other hand, in the demodulation device for demodulating the MSK wobble signal read out from the optical disc, as shown in Fig. 3, the analog mixers 10 and 11, the interval integrators 12 and 13, the phase determiners 14 and 15, and logic are shown. A circuit 16 is included. In the analog mixers 10 and 11, the wobble signal read out from the optical disc includes the first and second encoding frequencies ( , ), The wobble signal of the corresponding frequency is extracted, and the interval integrators 12 and 13 integrate the extracted wobble signal of the corresponding frequency in a predetermined section, and in the phase determiner 14 and 15, The integral value is compared with a preset reference value (Threshold = 0) to determine a phase.

The logic circuit 16 interleaves the determined phases to restore and output binary sequence bit string data, that is, original wobble data. Therefore, the MSK wobble signal recorded in the pulse waveform which is naturally continuous by the MSK modulation method is demodulated and output as wobble data without high frequency noise by the demodulation device configured as described above.

However, when the rotational speed of the optical disk is changed by the spindle servo operation in the optical disk device, since the frequency of the wobble signal read out from the optical disk is variable, the first and second encodings applied to the analog mixer 20 respectively. Frequency must be varied, which requires a complex hardware configuration and demodulation algorithm.

Therefore, the present invention was created to solve the above problems, and when demodulating the MSK wobble signal, the demodulation operation of the optical disc wobble signal can be performed more accurately and quickly by using simple hardware and algorithm. SUMMARY OF THE INVENTION An object of the present invention is to provide a demodulation method of an optical disc wobble signal for compensating for a detection error of a wobble signal due to a defect or the like.

1 is a table illustrating equations and conditions applied to a general MSK wobble signal modulation method.

2 is a waveform diagram of an MSK wobble signal modulated by a general MSK wobble signal modulation method.

3 illustrates a configuration of a demodulation device of a general MSK wobble signal.

4 illustrates a configuration of an apparatus for modulating an optical disc wobble signal according to the present invention.

5 is a waveform diagram of an MSK wobble signal modulated by the optical disc wobble signal modulation method according to the present invention.

6 shows a configuration of an apparatus for demodulating an optical disc wobble signal according to the present invention.

7 shows each signal and wobble data detected by the optical disc wobble signal demodulation method according to the present invention;

8 is a flowchart illustrating a method for detecting a bit clock in a clock detector according to the present invention.

9 illustrates an embodiment of a bit clock detection process in a clock detector according to the present invention;

10 illustrates MSK binary sequences applied to an optical disc wobble signal demodulation method according to the present invention;

11 is a flowchart illustrating an operation of a method for demodulating an optical disc wobble signal according to the present invention.

12A and 12B show binary sequences of ADIP units detected by the demodulation method of an optical disc wobble signal according to the present invention,

FIG. 13 is a table showing the structure of an ADIP word applied to an optical disc wobble signal demodulation method according to the present invention;

14 is a flowchart illustrating an operation of generating and outputting pseudo packet data by the method for demodulating an optical disc wobble signal according to the present invention.

※ Explanation of code for main part of drawing

10,11: analog mixer 12,13: interval integrator

14,15: phase determination unit 16: logic circuit

20: I / Q message combination unit 21: frequency and phase determination unit

22: wobble signal recording unit 30: band pass filter

31: A / D converter 32: slope detector

33: peak detector 34: clock detector

35 bit detector 36 address decoder

In the demodulation method of an optical disc wobble signal according to the present invention for achieving the above object, at the falling edge of the bit clock of a predetermined period, the level value of the peak detection signal is checked, and the data of the binary signal corresponding to the level value is checked. Detecting a bit; Comparing the detected predetermined number of data bits with a plurality of preset ADIP units and detecting packet data of an ADIP unit whose type matches each other; And outputting an ADIP word, which is physical address information, with reference to the packet data of the detected ADIP unit.

In addition, the demodulation method of the optical disc wobble signal according to the present invention, when generating pseudo packet data, refers to at least one or more packet data previously detected or generated to determine the type of packet data to be generated at present. Confirming step 1; When the type of the checked packet data corresponds to the data unit Data_x among a plurality of preset ADIP units, it is determined whether the data bit '11' is detected second from the beginning of the predetermined number of data bits sequentially stored. Two steps to confirm; And when the data bit '11' is detected for the second time, generating pseudo packet data of different data units according to the detected position.

Hereinafter, a preferred embodiment of a method for demodulating an optical disc wobble signal according to the present invention will be described in detail with reference to the accompanying drawings.

4 shows a configuration of an apparatus for modulating an optical disc wobble signal according to the present invention. The modulation device includes an in-phase and quadrature message combiner 20, a frequency and phase determiner 21, and an MSK wobble signal recorder 22. The in-phase and quadrature message combiner At 20, as described above, the in-phase message m _I and the quadrature message m _Q of the wobble data to be recorded as the physical address information of the optical disc are always combined into ( m _I , m _Q ). .

On the other hand, in the frequency and phase determination unit 21, a combination value of ( m _I , m _Q ), that is, (1,1), (1,0), (0,1), (0,0) Depending on which one determines two different frequencies f ₁ , f ₂ and two phases P ₁ , P ₂ , four different waveforms, i.e. , , , And The MSK wobble signal is generated, wherein the first and second frequencies are determined to be values satisfying the following equation.

--- Equation (2)

--- Equation (3)

Here, K and P are natural numbers and K-P = 1 is satisfied.

That is, the frequency and phase determiner 21 determines the first and second frequencies f ₁ and f ₂ as values satisfying equations (2) and (3) defined by the MSK modulation scheme, respectively. However, if the values of K and P are natural and at the same time determine to have a value satisfying KP = 1, the minimum value of the MSK wobble signal is satisfied when the condition (K, P is a natural number, KP = 1) is satisfied. Alternatively, the maximum peak point is always formed at the time when the first frequency and the second frequency are changed.

For example, when the first frequency and the second frequency satisfy K = 3, P = 2, and KP = 1 , The case is determined in detail as follows.

First, as shown in FIG. 5, when the wobble data to be recorded on the optical disc is '00110' bit string data, the combination of the in-phase message m _I and the quadrature message m _Q is always ( m _I). , m _Q ), so that ( m _I , m _Q ) for the first bit '0' becomes (0,0) by combining with the second bit '0' and the second bit '0' For ( m _I , m _Q ) is (1,0) by combination with the third bit '1'.

Thus, by ( m _I , m _Q = 0,0) for the first bit '0', the second frequency f ₂ has a 180 degree phase π. Is generated, and has a first frequency (f ₁ ) and a zero phase by ( m _I , m _Q = 1,0) for the second bit '0'. Pulse signal is generated.

In addition, by ( m _I , m _Q = 1,1) for the third bit '1', a second frequency f ₂ and a zero phase are obtained. Pulse signal is generated and has a first frequency f ₁ and a 180 degree phase π by ( m _I , m _Q = 0,1) for the fourth bit '1'. Pulse signal is generated.

That is, when the values of K and P are natural numbers and have a value satisfying K-P = 1, the MSK wobble signal has a minimum / maximum peak point when the first frequency and the second frequency are changed.

On the other hand, as shown in Fig. 6, the demodulation device for demodulating the MSK wobble signal modulated and recorded as described above includes a band pass filter 30, an A / D converter 31, a slope detector 32, and a peak detector ( 33), a clock detector 34, a bit detector 35, and an address decoder 36, wherein the band pass filter 30 is configured for the push-pull signal read out from the optical disk. The analog wobble signal is band filtered to a predetermined frequency band, for example, 0.8 MHz to 2.2 MHz to remove high frequency noise components, and the A / D converter 31 converts the band pass filtered analog wobble signal into a digital wobble signal. Will be converted to.

The slope detector 32 monitors and detects the slope of the A / D-converted digital wobble signal, and the peak detector 33 minimizes the point where the detected slope is changed from negative to positive. The peak point is detected, the point where the detected slope is changed from positive to negative is detected as the maximum peak point, and the corresponding peak detection signal is output.

For example, as shown in FIG. 7, when the original wobble bit data '0100111011' is calculated by using an exclusive logical OR (XOR) and precoded, the precoded data becomes '110100110', which is the first code. When modulating an analog wobble signal by the frequency and the second frequency, the levels of the start peak and the end peak are opposite to each other or have the same pulse waveform.

Therefore, the peak detection signal detected and output by the peak detector 33 has two kinds of periods in which the periods of the level transition points are different from each other. In this case, the clock detector 34 determines the level transition points. Each cycle is detected, and a bit clock signal having a constant cycle which is the least common multiple of two different cycles is detected and output.

On the other hand, as shown in Fig. 7, the bit clock of the constant period becomes a clock signal having the same period as the bit transition point of the original wobble bit data. In the bit detector 35, the bit clock signal falls. At the edge, the level value of the peak detection signal detected and output from the peak detector 33 is detected and confirmed.

At this time, the bit detector 35, at the falling edge of the detected bit clock signal, if the level value of the peak detection signal is Low (0), if the high (Wol), the wobble data of '1' Detection output.

Therefore, since the decoded data output by the address decoder 36 is demodulated to a value of '0100111011' which is the same as the original wobble data sequence as shown in FIG. 7, the wobble PLL circuit is replaced as described above. It does not need to be used, and also the configuration of algorithms and hardware for discriminating modulation frequency and phase can be omitted.

On the other hand, in the clock detector 34 described above with reference to Figs. 6 and 7, the level shift period of the peak detection signal detected and output from the peak detector 33 is monitored so that the bit clock signal of a certain period is accurately corrected. The bit clock detection method for detecting will be described in detail as follows.

First, in the clock detector 34, as shown in Figs. 8 and 9, time counts are performed between the edges of the peak detection signal, and the cumulative average value T _avg for the time count value is continuously maintained. In operation S10, since the pulse values of short periods in the MSK wobble signal are only less than about 10% of the total, the cumulative average value is the time count for the long period of the MSK wobble signal. Gradually, it's almost like a value.

On the other hand, the clock detector 34 time-counts between falling edges of the peak detection signal, and compares the time count value T _ff with the cumulative average value T _avg (S11). .

For example, as shown in FIG. 9, the time count value T _1-3 between the first falling edge 1 and the next falling edge 3 of the peak detection signal is 120, and the cumulative average value is 120. When (T _avg ) is 174, the bit detector determines that the time count value T _1-3 between the falling edges 1-3 is smaller than a cumulative average value (T _1-3 <T _avg ), The next rising edge 4 is detected, and the time count value T _1-4 until then is again compared with the cumulative mean value, wherein the time count value is greater than the cumulative mean value 174. In the case of a large 180, the bit clock is level shifted and the time count value T _1-4 is initialized to zero (S12).

Subsequently, time counting is performed between rising edges. If the time count value T _1-3 between the falling edges is larger than the cumulative average value (T _1-3 > T) _avg ), the clock detector level shifts the bit clock, initializes the time count value (T _1-3 ), counts the time between the next falling edges (3-5) and counts the time A series of operations of comparing the values T _3-5 with the cumulative average value T _avg is repeated (S13).

On the other hand, in the clock detector, if the time counting between the rising edge (Rising Edge) through the above process, for example, as shown in Figure 9, the second rising edge (4) from the next The time is counted between the rising edges 6, and the time count value T _4-6 is compared with the cumulative average value (S14).

In addition, when the time count value T _4-6 is 120 and the cumulative average value T _avg is 174, in the clock detector, the time count value T ₄ between the rising edges 4-6 is measured. _-6 ) determines that it is smaller than the cumulative average value (T _4-6 < T _avg ), and detects the next falling edge 7, and accumulates the time count value T _4-7 until then. When the time count value is 180 which is greater than the cumulative average value 174, the bit clock is level shifted and the time count value T _4-7 is initialized to zero. (S15).

In addition, thereafter, time counting is performed between falling edges again. If the time count value T _4-6 between the rising edges is larger than the cumulative average value (T _4-6 > T _avg ), the clock detector level shifts a bit clock, initializes the time count value T _4-6 , and then counts the time between the next rising edges 6-8 to determine the time. A series of operations of comparing the count value T _6-8 with the cumulative average value T _avg is repeatedly performed (S16).

Therefore, the clock detector repeats the above-described process, and thus accurately detects and outputs a bit clock signal of a predetermined period as shown in FIG. 9.

Meanwhile, as described above, the address decoder 36 sequentially stores 56 binary signals continuously detected from the bit detector 35, and is set in advance as shown in FIG. 10. Each of the eight types of Address In Pre-Groove Word (ADIP) units are compared.

That is, the monotone unit, the data start indication information unit, the synchronization signal units Sync 0 to 3, and the data units Data 0 and 1, which are differently represented by 56 data bits. And 56 binary signals continuously detected from the bit detector 35 are compared with each other to detect any one type of ADIP unit that matches.

Thereafter, one ADIP word (ADIP Word = 83 ADIP Units), which is physical address information, is generated and output with reference to the 83 ADIP units detected as described above.

First, FIG. 11 is a flowchart illustrating a method of demodulating an optical disc wobble signal according to the present invention. In the bit detector 35, a count value of a bit clock output from the clock detector 34 is zero. (S30), and when the bit clock output from the clock detector 34 is detected (S31), at the time when the bit clock transitions from the high level to the low level, from the peak detector 33 The level of the peak detection signal output is checked to detect and output a data bit of '0' or '1'. At this time, the address decoder 36 detects and outputs a '0' from the bit detector 35. Alternatively, the data bits of '1' are temporarily stored sequentially (S32).

In addition, when the bit detector 35 accumulates and increments the count value of the bit clock output from the clock detector 34 one by one (S33), when the cumulatively increased count value of the bit clock is '56'. (S33), the address decoder 36 compares the temporarily stored data bits, that is, 56 data bits, sequentially with the eight types of ADIP units described above with reference to FIG. Will detect any one type of ADIP unit that matches.

That is, as shown in FIGS. 12A and 12B, the types of the detected 56 data bits are identified, and an ADIP unit corresponding to the type is a monotone unit or a data start instruction. It is detected whether any one of the information unit (Reference Unit), the synchronization signal units (Sync 0 to 3), and the data units (Data 0, 1) matches the ADIP unit (S34).

When any one type of ADIP unit is detected through the above process, packet data corresponding to the type of the ADIP unit is detected and sequentially stored (S35).

On the other hand, when the 56 data bits are compared with the eight types of ADIP units, and a matched type of ADIP unit is not detected, the address decoder 36 may cause a defect due to an optical disc. It is determined that an error in detecting the wobble signal has occurred, and the current packet data position is confirmed (S36).

For example, the previous packet data normally detected through the above process is a data unit (data_x) corresponding to the 10th (ADIP unit number 9) of 83 ADIP units, as shown in FIG. In this case, the packet data corresponding to the current ADIP type to be detected is determined as the data unit data_x corresponding to the 11th (ADIP unit number 10) of 83 ADIP units, and the corresponding pseudo packet data (Pseudo Packet) Data) is generated (S37).

In addition, the address decoder sequentially stores the 83 packet data detected or generated as described above (S38), and then refers to the 83 packet data to store one ADIP word, which is physical address information. 83 ADIPUnits) to perform a series of operations to generate and output (S39).

Meanwhile, in the address decoder 36, valid sync units Sync_0, Sync_1, Sync_2, and Sync_3 are continuously detected as shown in FIG. 13 while generating and temporarily storing pseudo packet data as described above. In this case, the generation and processing operation of the ADIP word, which is physical address information, is ignored, and after the valid synchronization units are detected, the operation of newly generating and processing the ADIP word is performed again with reference to the packet data detected or generated. do.

Accordingly, it is possible to fundamentally prevent incorrect physical address information from being output by randomly generated pseudo packet data.

In addition, when the pseudo decoder data is generated in the address decoder 36 as described above, in particular, when generating the pseudo packet data corresponding to the data unit Data_x, a dictionary of 'Data 0' or 'Data 1' is used. Only pseudo packet data corresponding to any one of the ADIP units set in, for example, pseudo packet data of the ADIP unit corresponding to 'Data 0' is repeatedly generated.

In this case, as described above, the pseudo packet data corresponding to the data unit has a probability of 50%. In the following, the accuracy of the pseudo packet data corresponding to the data unit can be improved higher than 50%. The method will be described in detail.

Fig. 14 shows an operation flowchart for generating pseudo packet data corresponding to a data unit by the optical disc wobble signal demodulation method according to the present invention. In the address decoder 36, as described above, the bit detector When 56 data bits detected from (35) are compared with eight types of ADIP units, and a matching type of ADIP unit is not detected among them, a wobble signal detection error is caused by a defect of an optical disk or the like. Is determined, and the current packet data position is checked (S50).

E.g. If the previous packet data normally detected is packet data data_x of the type corresponding to the tenth (ADIP unit number 9) of 83 ADIP units, the ADIP unit to be detected now The packet data corresponding to the packet data corresponding to the packet data (data_x) corresponding to the eleventh (ADIP unit number 10) of the 83 ADIP units is determined and confirmed (S51).

At this time, the address decoder 36 detects whether a second data bit '11' exists in the 56 temporarily stored data bits (S52), and the second data bit '11' When it is detected, it is determined whether to generate pseudo packet data corresponding to 'Data 1' or 'Data 0' according to the detection position.

That is, when the position where the second '11' exists in the 56 data bits exists at a position spaced 10 data bits away from the first data bit '11', as shown in FIG. 12A, the 'Data' If it is determined to generate pseudo packet data corresponding to 1 'and exists in a position spaced apart by 12 data bits from the first data bit' 11 ', generation of pseudo packet data corresponding to' Data 0 'is performed. It is determined (S53).

On the other hand, when '10' or '01' is detected instead of the second data bit '11', the second detected position of '1' is 10 or 11 from the first data bit '11'. It is checked whether the data exists at positions spaced apart by the data bits (S55), and it is determined whether to generate packet data corresponding to 'Data 1' or 'Data 0' according to the check result.

For example, in the address decoder 36, when the second detected position of '1' exists at a position spaced apart by 10 or 11 data bits from the first data bit '11', 'Data 1' It is determined to generate the packet data corresponding to '(S56), and when present in a position further than 10 or 11 data bits from the first data bit' 11 ', corresponding to' Data 0 ' The generation of the packet data is determined (S57).

On the other hand, when the second data bit '11', as well as '10' or '01' is not detected, any one of the preset packet data, that is, 'Data 0' or 'Data 1', which is previously set It is determined to generate pseudo packet data corresponding to one data unit, for example, pseudo packet data of an ADIP unit corresponding to 'Data 0'.

Thereafter, the address decoder generates pseudo packet data corresponding to the data unit determined through the above process, or if the current packet data position does not correspond to the data unit, the pseudo of the corresponding ADIP unit. A series of operations for generating packet data is performed (S59).

Accordingly, the pseudo packet data corresponding to the data unit has a probability much higher than 50%.

Or more, preferred embodiments of the present invention described above, which is posted for the purpose of illustration, those skilled in the art to improve the various other embodiments within the spirit and technical scope of the present invention disclosed in the appended claims below Changes, substitutions or additions will be possible.

The optical disc wobble signal demodulation method according to the present invention constituted and constructed as described above comprises a plurality of preset ADIP units for a predetermined number of data bits to be detected based on a predetermined period of a bit clock and a level value of a peak detection signal. Compared with the present invention, after detecting the packet data of the ADIP unit, referring to the packet data of the ADIP unit, generating and outputting the ADIP word, which is physical address information, and generating the pseudo packet data, By identifying the type of packet data to be generated, and generating the corresponding pseudo packet data more accurately, using a simple hardware and algorithm, more accurate and faster demodulation of the optical disc wobble signal is possible, as well as a defect of the optical disc. It is possible to compensate the detection error of the wobble signal due to Very useful inventions that allow.

Claims (5)

When necessary to generate pseudo packet data, identifying a type of packet data to be currently generated by referring to at least one or more packet data previously detected or generated; When the type of the checked packet data corresponds to the data unit Data_x among a plurality of preset ADIP units, it is determined whether the data bit '11' is detected second from the beginning of the predetermined number of data bits sequentially stored. Two steps to confirm; And And a second step of generating pseudo packet data of different data units according to the detection position when the second data bit '11' is detected secondly. The method of claim 1, The first step compares 56 bit data with eight types of preset ADIP units, and if no one ADIP unit whose type matches each other is detected, it is necessary to generate pseudo packet data. And demodulating the optical disc wobble signal. The method of claim 1, In the third step, when the second detected position of the data bit '11' is spaced apart from the first detected data bit '11' from the first of the 56 stored data bits by 10 data bits, Generating and outputting pseudo packet data corresponding to Data 1, and generating and outputting pseudo packet data corresponding to 'Data 0' when spaced apart by 12 data bits from the first data bit '11'. An optical disk wobble signal demodulation method. The method of claim 1, In step 3, when the data bit '11' is not detected twice, instead '10' or '01' is detected, the detection position of the '1' is the first detected data bit '11'. 10 or 11 data bits spaced apart from each other, and generate and output packet data corresponding to 'Data 1', and 10 or 11 data bits from the first data bit '11'. If present in a more spaced position, the optical disk wobble signal demodulation method, characterized in that for generating and outputting the packet data corresponding to 'Data 0'. The method of claim 1, In the third step, when the second data bit '11' is not detected and '10' or '01' is not detected, any one of 'Data 0' or 'Data 1' is set in advance. And generating and outputting pseudo packet data corresponding to the data unit.