KR100545804B1 - Wobble signal detection apparatus and method in wobble phase locked loop - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for detecting a wobble signal in a wobble phase locked loop. In a wobble phase locked loop (Wobble PLL), an analog wobble signal of an optical disc is subjected to band pass filtering and A / D conversion, and then A Detects the slope of the wobble signal / D-converted, determines the peak point of the wobble signal, and detects the peak point of the wobble signal. Detects a slope by calculating and accumulating a change value of the wobble signal data sampled within a predetermined interval and a different weight set in advance, and detecting a slope to form a notch or spark shape in the analog wobble signal. It is a very useful invention that the slope detection error due to the induction of high frequency noise can be prevented in advance, so that a stable wobble signal can be detected.

Wobble Signal, Wobble Phase-Locked Loop, Slope Detection, Weight, Window

Description

Apparatus and method for detecting a wobble signal in wobble phase locked loop}             

1 shows a configuration for a typical wobble phase locked loop (Wobble PLL),

2 shows a waveform diagram for a PLL clock phase corrected by a typical wobble phase locked loop,

3 shows phase error in a typical wobble phase locked loop, PLL clock and time count values in a digitally controlled oscillator,

FIG. 4 is a waveform diagram of the wobble signals abnormally detected in a typical wobble phase locked loop.

5 illustrates a configuration of a wobble phase locked loop to which the wobble signal detecting apparatus and method according to the present invention are applied.

6 illustrates a slope detection process of a wobble signal according to the present invention.

7 illustrates a slope detection waveform diagram of a wobble signal according to the present invention;

8 illustrates a peak detection process of a wobble signal according to the present invention.

9 illustrates a peak detection waveform diagram of a wobble signal according to the present invention;

10 is a waveform diagram of wobble signals normally detected by the wobble signal detection apparatus and method according to the present invention.

11 illustrates a state in which a high frequency noise is included in a wobble signal input to a slope detector according to the present invention.

12 illustrates a slope detection process of a wobble signal according to another embodiment of the present invention,

13 illustrates a slope detection waveform diagram of a wobble signal detected according to another embodiment of the present invention.

※ Explanation of code for main part of drawing

10: band pass filter 11: A / D converter

12,22: wobble signal detector 13: phase error detector

14 loop filter 15 digitally controlled oscillator

16 bit detector 17 sync detector

18: address decoder 21: slope detector

100,200: wobble phase locked loop 300: main phase locked loop

According to the present invention, a write clock or a read clock generated and output in a main phase lock loop (Main PLL) for recording or reproducing data of an optical disc such as a recordable CD (CD) or a DVD (DVD) The present invention relates to an apparatus and method for detecting a wobble signal in a wobble phase locked loop for synchronizing with a wobble signal read from an optical disc.

First, FIG. 1 schematically illustrates a configuration of a general wobble phase locked loop. In the wobble phase locked loop 100 (hereinafter, referred to as a 'Wobble PLL'), a wobble signal detector 12 and a phase error are shown. A detector 13, a loop filter 14, and a digital controlled oscillator (DCO) 15 are included.

 On the other hand, the wobble signal read out from the recordable optical disc, for example, an optical disc such as DVD-RW (DVD-Rewritable), is filtered by the band pass filter (BPF) 10 as a push-pull signal, After the high frequency noise, the DC offset component, etc. are removed, the A / D converter 11 converts the digital signal into a digital signal.

In the wobble signal detector 12 of the Wobble PLL 200, the A / D converted wobble signal is sliced on the basis of a preset reference level, for example, a zero level. As shown in FIG. 2, the detection output is performed as a wobble signal in the form of a square wave, and the phase error detector 13 detects the PLL clock output from the digitally controlled oscillator 15 and the wobble signal detector 12. The phase error between the output wobble signals is calculated and output to the loop filter 14.

 The loop filter 14 generates a phase correction value for the PLL clock of the digitally controlled oscillator 15 based on the phase error value output from the phase error detector 13. The filter acts as a kind of low pass filter (LPF) such that the PLL clock output from the digitally controlled oscillator is synchronized with the wobble signal.

 The digitally controlled oscillator 15 corrects the oscillation frequency of the current PLL clock according to the phase correction value generated and output from the loop filter 14 to generate and output a PLL clock synchronized with the wobble signal. .

On the other hand, the PLL clock generated and output by the Wobble PLL 100 is applied to the bit detector 16 to which the A / D converted wobble signal is input, and the bit detector 16 uses the PLL clock. Thus, the A / D converted wobble signal is detected and converted into a bit stream having a value of 1 or 0.

The sync detector 17 which detects a sync pattern loaded on the wobble signal from the bit stream generates and outputs a sync signal corresponding to the sync pattern. In the address decoder 18 for decoding the physical address, the decoding operation is performed based on the synchronization signal of the synchronization detector 17 to output the physical address of the optical disc to the main synchronization phase loop 300.

On the other hand, in the phase error detector 13 of the general Wobble PLL 100 as described above, as shown in Figure 3, the A / D converted wobble signal is positive (positive) to negative (Zero) A phase error is detected at a point crossing point (NZCP: Negative Zero Crossing Point, hereinafter referred to as 'NZCP'), and a time count value for determining the oscillation frequency of the digitally controlled oscillator 15, for example, a free reduction. The (Free Down) time count value is always corrected by the phase error value detected at the NZCP time point.

At this time, when the phase of the PLL clock generated by the digitally controlled oscillator 15 is ahead of the phase of the A / D converted wobble signal (Lead Case), the phase error detector 13, as shown in FIG. Similarly, the positive phase error is detected, generated, and output to the loop filter 14. In the loop filter, a time count value for determining the clock frequency of the digitally controlled oscillator 15 is smallly corrected according to the positive phase error value. Done.

When the phase of the PLL clock generated by the digitally controlled oscillator 15 falls behind the phase of the A / D converted wobble signal (Lag Case), in the phase error detector 13, as shown in FIG. Similarly, a negative phase error is detected and generated and output to the loop filter 14, wherein the loop filter increases a time count value for determining a clock frequency of the digitally controlled oscillator 15 according to the negative phase error value. Will be corrected.

Accordingly, the Wobble PLL 100 detects a phase error value at the NZCP time point and corrects a time count value that determines the clock frequency of the digitally controlled oscillator 15 so that the PLL clock is synchronized with the wobble signal. The phase error correction operation is continuously performed.

However, in recent years, as the recording density of the optical disc becomes higher, the pitch of the recording track becomes more dense, so that the crosstalk effect due to the wobble signal of the adjacent track becomes larger, and the wobble output through the band pass filter 10. Since the signal-to-noise ratio of the signal becomes very small, there is a problem that the detection of the stable wobble signal cannot be achieved by the conventional method.

In addition, when the tracking servo and the focusing servo are unstable or surface vibration of the optical disk occurs, a low frequency wave component and a DC offset component are introduced into the wobble signal output through the band pass filter 10, or When the amplitude of the wobble signal is varied, for example, as shown in FIG. 4, when the wobble signal output through the band pass filter is output as a stable wobble signal having a predetermined amplitude (①), The stable wobble signal ② is normally detected by the wobble signal detector 12, but a low frequency wave component and a DC component offset component are introduced into the wobble signal output through the band pass filter (③), or the wobble signal. In the case where the variable amplitude of the signal and the DC offset component are introduced (⑤), abnormal wobble signals (④, ⑥) are detected by the wobble signal detector 12. There was a problem that the phase error correction operation in the wobble phase locked loop could not be performed normally.

Accordingly, the present invention was created to solve the above problems, and in the wobble phase locked loop (Wobble PLL), the analog wobble signal of the optical disc is subjected to band pass filtering and A / D conversion, and then the A / D conversion. Detects the slope of the wobble signal, determines the peak point of the wobble signal, and detects a wobble signal in the form of a square wave transitioning to a high level or a low level at the peak point, and sampled within a predetermined interval. The slope detection error due to the inflow of a notch or spark-like high frequency noise into the analog wobble signal is detected by calculating and accumulating the change value of and a preset different weight value and detecting the slope of the wobble signal. To provide an apparatus and method for detecting a wobble signal in a wobble phase-locked loop to be prevented in advance. A.

According to an aspect of the present invention, there is provided an apparatus for detecting a wobble signal in a wobble phase locked loop, comprising: A / D converting means for A / D converting an analog wobble signal read out from an optical disk and filtered through a band pass; Slope detection means for detecting a slope of the wobble signal according to the change value of the A / D converted wobble signal; And detecting a peak point of the wobble signal using the detected wobble signal slope, and then detecting and outputting a wobble signal in the form of a square wave transitioning to a high or low level based on the peak point. And the slope detection means calculates a change value of the wobble signal data sampled within a predetermined section in which the A / D-converted wobble signal is sampled at least two, and different preset weights. And accumulate, characterized in that for detecting the slope,

In addition, the wobble signal detection method in the wobble phase locked loop according to the present invention is a step 1 of bandpass filtering and A / D conversion of the analog wobble signal of the optical disk, and then detecting the slope of the A / D converted wobble signal ; Detecting a peak point of the wobble signal by using a slope of the detected wobble signal; And detecting and outputting a wobble signal in the form of a square wave transitioning to a high level or a low level based on the detected peak point of the wobble signal, wherein slope detection of the wobble signal is performed within a predetermined section. Comparing a plurality of wobble signal data, each sampled, with one reference wobble signal data, calculating the difference in magnitude, and multiplying the values by different weights, and comparing the accumulated value with a preset reference value. Characterized in that for detecting the slope.

Hereinafter, a preferred embodiment of an apparatus and method for detecting a wobble signal in a wobble phase locked loop according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 illustrates a configuration of a wobble phase locked loop to which a wobble signal detection apparatus and method according to the present invention are applied. The wobble PLL 200 includes a slope detector 21 and a wobble signal detector 22. And a phase error detector 23, a loop filter 24 and a digitally controlled oscillator (DCO) 25. In the slope detector 21, as described above with reference to FIG. A positive slope and a negative slope of the converted wobble signal are detected, and the wobble signal detector 22 detects a peak point of the wobble signal based on the positive slope and the negative slope. Peak Point) is detected and detected, and a wobble signal in the form of a square wave which is level-transitioned to a high level or a low level at each peak point is detected and output.

On the other hand, the phase error detector 23 compares and calculates the phase error between the PLL clock output from the digitally controlled oscillator 25 and the wobble signal in the form of a square wave which is level-shifted at the peak point, and thereby the loop filter 24. ), The loop filter 13 generates a phase correction value for the PLL clock of the digitally controlled oscillator 25 based on the phase error value output from the phase error detector 23, Output to the digitally controlled oscillator.

Accordingly, the digitally controlled oscillator 25 corrects the current PLL clock oscillation frequency according to the phase correction value generated and output from the loop filter 24 to generate and output a PLL clock synchronized with the wobble signal. The PLL clock generated and output by the Wobble PLL 200 is applied to the bit detector 16 to which the A / D converted wobble signal is input, and the bit detector 16 uses the PLL clock. The A / D converted wobble signal is detected and converted into a bit stream having a value of 1 or 0.

The sync detector 17 which detects a sync pattern loaded on the wobble signal from the bit stream generates and outputs a sync signal corresponding to the sync pattern. In the address decoder 18 that decodes the physical address, the decoding operation is performed on the basis of the synchronization signal of the synchronization detector 17 to output the physical address of the optical disc to the main synchronization phase loop 300. A series of phase error correction operations for synchronizing with the wobble signal are continuously performed. The wobble signal detection operation performed by the slope detector 21 and the wobble signal detector 22 will be described in detail as follows.

6 and 7 illustrate a slope detection process of a wobble signal and a slope detection waveform diagram of the wobble signal according to the present invention. As shown in FIG. 6, a band pass filter 10 is used. When the output analog wobble signal is A / D-converted by the A / D converter 11 and input to the slope detector 21, the slope detector 21 applies the wobble signal that is converted to the A / D conversion. In order to remove the mixed high frequency noise components, the data of the wobble signal that has been A / D converted for a predetermined time, for example, 10% of the wobble signal period, is not the data of the digital wobble signal that has been A / D converted immediately before. And its size is compared.

When the comparison value differs from a preset reference value, for example, two bits or more, the slope of the wobble signal is detected. As shown in FIG. In the state of being sampled with 70 wobble signal data, the data of the digital wobble signal currently A / D converted is '1101 10XX' (XX is ignored), and the data of the digital wobble signal sampled before 10% of the wobble signal period, That is, if the wobble signal data sampled before 7 is '1111 01XX' (XX is ignored), the comparison value (1101 10XX-1111 01XX) becomes the '(-)' value and is more than two bits different. At this time, the slope of the wobble signal is determined, and in this case, the negative slope is detected.

On the other hand, when the comparison value becomes a '(+)' value that differs by two bits or more, the wobble signal slope is detected as a negative slope, and thus, in the slope detector 21, as shown in FIG. The negative slope detection signal that becomes high when the comparison value is '(-)' and the positive slope detection signal that becomes high when the comparison value is '(+)' are respectively detected and output.

Therefore, the positive slope detection signal and the negative slope detection signal input to the wobble signal detector 22 have different waveforms as shown in FIG.

8 and 9 illustrate a peak detection process of the wobble signal and a peak detection waveform diagram of the wobble signal according to the present invention. In the wobble signal detector 22, as described above, the positive signal is positive. When the slope detection signal and the negative slope detection signal are input, a virtual window is generated from a predetermined length, for example, from the positive slope detection signal to the negative slope detection signal, and the value of the positive slope existing in the window. The values of the and negative slopes are accumulated, respectively, and the length of the window may be set to a half value T / 2 of one period 1T of the wobble signal.

In addition, when the accumulated values of the positive slopes are larger than the accumulated values of the negative slopes, the high values are output when the accumulated values of the positive slopes are compared with each other, and the accumulated values of the positive slopes are the negative slopes. If it is smaller than the cumulative value of, the output will be Low.

Accordingly, the wobble signal detector 22 detects and determines the peak point of the analog wobble signal according to the positive slope detection signal and the negative slope detection signal, and has a square wave shape that transitions from the peak point to a high or low level. Since the wobble signal is detected and output, the analog wobble signal, the positive slope, the negative slope, and the wobble signal detected and output by the wobble signal detector have waveforms as shown in FIG. 9.

Therefore, as shown in FIG. 10, when the wobble signal output through the band pass filter is output as a stable wobble signal having a certain amplitude (1 '), the wobble signal detector 22 provides a wobble signal. When the stable wobble signal ② 'that is level-shifted at the peak point of? Is normally detected, the low frequency wave component and the DC offset component are introduced into the wobble signal output through the band pass filter (③'), or the wobble signal. Even when the variable amplitude and the DC offset component are introduced (5 '), the wobble signal detector 22 detects and outputs stable wobble signals 4' and 6 'which are level shifted from the peak point of the wobble signal. .

For reference, a series of operations for correcting the phase error of the PLL clock by using the wobble signal detected through the above process may be replaced with various other embodiments, and also referred to as 'MSK' described in FIGS. 4 and 10. 'Signal' is a conventional wobble signal modulated by the 'Minimum Shift Keying' modulation method, which is one of various wobble signal modulation methods.

On the other hand, when a high frequency noise of notch or spark shape is introduced into the analog wobble signal filtered through the band pass filter 10, a slope detection error for the wobble signal occurs due to the high frequency noise. The slope detection method for preventing the case will be described in detail with reference to the accompanying drawings as follows.

First, as shown in FIG. 11, when noise of a high frequency component flows into an analog wobble signal (dotted line display) filtered through the band pass filter 10, the A / D converter 11 has a notch or A wobble signal (bold solid line display) containing spark-shaped high frequency noise is input.

Accordingly, the wobble signal data sampled and A / D converted by the A / D converter 11 has a data value that is irregularly increased or decreased by the notch or spark-shaped noise. As shown in Fig. 11, when the values of the wobble signal data obtained by sampling the wobble signal including the high frequency noise are sampled by X (0) to X (n) (Good Sampling Case), they correspond to the original wobble signal. Although the wobble signal data is normally output to the slope detector 21, the values of the wobble signal data obtained by sampling the wobble signal including the notch and the spark-shaped high frequency noise are X '(0) to X' (n). In the case of sampling with (Bad Sampling Case), wobble signal data different from the original wobble signal is output to the slope detector 21.

That is, as in the section 'A' shown in FIG. 11, the value X '(1) of the wobble signal data sampled in the n + 2 th is the value X of the wobble signal data sampled in the n + 3 th. Since it has a relatively large value as compared with (2)), when the wobble signal data values are compared and the slope is determined, the wobble signal decreases despite the increase of the original wobble signal. This is wrongly detected by the slope.

Therefore, in the slope detector 21, as shown in FIG. 12, a window of a predetermined section in which predetermined wobble signal data values X (0) to X (10) are sampled. ), The value of each wobble signal data (sequentially sampled), which is sequentially sampled, using the value of the first wobble signal data (X (0)) sampled in the window as a reference wobble signal data value. After comparison with X (10), the difference values are calculated, respectively, and the weights W (1) to W (10) are respectively multiplied with the difference values.

Then, after accumulating all the values multiplied by the different weights as described above, a positive threshold value previously set to detect a positive threshold value and a negative slope set in advance to detect the positive slope is set. Value), and detects and outputs a positive slope and a negative slope with respect to the wobble signal in the window.

In this case, the weights W (1) to W (10) may be the first wobble signal data value X (0) sampled in the window and values of each wobble signal data sequentially sampled thereafter. Preset to a value (W (1) <W (2) ... W (2) <W (10)) that increases in proportion to the time difference or separation distance between (X (1) to X (10)) do.

In addition, when the slope of the wobble signal in the corresponding window (Window 1) is detected through the above process, the window is shifted to the next window (Window 2), as shown in FIG.

Accordingly, in the slope detector 21, the values of the wobble signal data sampled in the corresponding window based on the first wobble signal data value X (1) in the shifted window (Window 2). By comparing (X (1) to X (11)), a series of operations of calculating the difference value and multiplying different weights are repeatedly performed.

-- 식 1

Equation 1

Where N is the size of data to accumulate, X (n) is sampled data, X (0) is sampled reference data, and W (n) is the weight of the slope of two sampled data, Sp (k) Is a value obtained by accumulating the weight of the positive slope of each sampled data based on X (0), Sn (k) is a value obtained by accumulating the weight of the negative slope of each sampled data based on X (0), Pth Is defined as the positive reference value, Nth is the negative reference value, and Slope (n) is the slope at X (0).

Accordingly, since the positive slope detection signal and the negative slope detection signal detected and output by the above-described equation and operation are output as a stable waveform from which high frequency noise components are removed, as shown in FIG. The wobble signal detector 22 can detect the peak point more accurately, and even when the analog wobble signal contains notched or spark-shaped high frequency noise, the slope detection error for the wobble signal is caused by the high frequency noise. Can be prevented from occurring.

The above-described preferred embodiment of the present invention has been disclosed for purposes of illustration, and the slope detector 21, the wobble signal detector 22, and the phase error detector 23 may be integrated into one configuration. In addition, it will be apparent to those skilled in the art that various other embodiments may be improved, modified, replaced, or added to within the spirit and scope of the present invention disclosed in the appended claims.

 The wobble signal detection apparatus and method in the wobble phase locked loop according to the present invention constituted and constructed as described above, in the wobble phase locked loop, perform a band pass filtering and A / D conversion of an analog wobble signal of an optical disc, and then A Detects the slope of the wobble signal / D converted to determine the peak point of the wobble signal, and detects a wobble signal in the form of a square wave transitioning to a high level or a low level at the peak point, but is sampled within a predetermined section. By detecting and accumulating the change value of the wobble signal data and different preset weights, the slope detection error due to the inflow of notch or spark high frequency noise into the analog wobble signal is not shown. It is a very useful invention that can be prevented, it is possible to detect a stable wobble signal.

Claims (13)

A / D conversion means for A / D converting the analog wobble signal read out from the optical disc; Slope detection means for detecting a slope of the wobble signal according to the change value of the A / D converted wobble signal; And Wobble signal detection means for detecting a peak point of the wobble signal using the detected wobble signal slope, and then detecting and outputting a wobble signal in the form of a square wave transitioning to a high level or a low level based on the peak point. Consists of including The slope detecting means detects a positive slope value and a negative slope value according to a change value of the wobble signal data sampled within a predetermined section in which the A / D converted wobble signal is sampled at least two or more, And the wobble signal detecting means detects a peak point of the wobble signal based on the positive slope value and the negative slope value. The method of claim 1, The slope detecting means compares a plurality of wobble signal data respectively sampled in the predetermined section with any one reference wobble signal data, calculates a magnitude difference, and multiplies the values by different weights. And comparing the accumulated value with a preset reference value to detect and output the positive slope and the negative slope of the wobble signal, respectively. The method of claim 2, The different weights are previously set to different values that are increased in proportion to a time difference or a separation distance between the reference wobble signal data value and each of the sampled wobble signal data values. Wobble signal detection device in a loop. The method of claim 2, The reference wobble signal data is first wobble signal data sampled in the predetermined section. The method of claim 2, And the predetermined section is limited by a window corresponding to a section length in which at least two or more wobble signal data are sampled. The method of claim 5, In the wobble phase synchronization loop, the slope detection means repeats the slope detection after shifting the window of the predetermined section so that the reference wobble signal data becomes the next sampled wobble signal data. Wobble signal detection device. A / D converting the analog wobble signal read out from the optical disc, and then detecting the slope of the A / D converted wobble signal; Detecting a peak point of the wobble signal by using a slope of the detected wobble signal; And And detecting and outputting a wobble signal in the form of a square wave transitioning to a high level or a low level based on the detected peak point of the wobble signal, The slope detection of the wobble signal may compare a plurality of wobble signal data, each being simplified within a predetermined interval, with any one reference wobble signal data to detect a positive slope value and a negative slope value. The wobble signal detection of the square wave form detects the peak point of the wobble signal based on the positive slope value and the negative slope value. delete The method of claim 7, wherein The reference wobble signal data is first wobble signal data sampled in the predetermined section. The method of claim 7, wherein The predetermined section is limited by a window corresponding to a section length in which at least two or more wobble signal data are sampled. The method of claim 10, After determining the slope in step 3, shifting the window corresponding to the predetermined interval so that the reference wobble signal data becomes the next sampled wobble signal data, and then repeatedly performing the slope detection. A wobble signal detection method in a wobble phase locked loop, characterized in that made. The method of claim 7, wherein Comparing the plurality of wobble signal data with the wobble signal data, calculating a magnitude difference, respectively, multiplying the weighted values by different weights, and comparing the accumulated wobble signal data with a preset reference value to determine the wobble signal. And detecting and outputting a positive slope and a negative slope of the wobble signal detection method. The method of claim 12, In the wobble phase lock loop, the different weights are previously set to different values that increase in proportion to a time difference or a separation distance between the reference wobble signal data and each of the sampled wobble signal data. Wobble signal detection method.

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