JP2009527069A - Signal quality evaluation apparatus and method, and optical disk driver - Google Patents

Abstract

The present invention relates to a signal quality evaluation apparatus and method for evaluating the quality of an input signal, and an optical disk driver having the signal quality evaluation apparatus. The apparatus according to the present invention detects a level value of an input signal by a binary signal of the input signal. A level value detection unit, an input signal configuration unit that configures a plurality of input signals using a detected level value and a predefined binary signal, and a quality of the input signal by calculation between the plurality of input signals. The required quality calculation unit is provided.

Description

  The present invention relates to a signal quality evaluation apparatus and method for evaluating the quality of an input signal, and an optical disk driver having a signal quality evaluation apparatus.

  The input signal is an analog signal such as an RF signal reproduced from the recording medium. For example, even if an RF (Radio Frequency) signal read from the disk has an analog signal property due to the disk characteristics and the optical characteristics of the optical disk driver, the disk is a recording medium on which a binary signal is recorded. Therefore, the optical disk driver can perform a binarization process for changing the RF signal into a binary signal. The binarization process can be performed using the comparator 100 as shown in FIG.

  FIG. 1 is a functional block diagram showing a general binarization process. Referring to FIG. 1, the binarization process is performed using a comparator 100 and a low-pass filter 110. The comparator 100 compares the input RF signal with the slicing level and outputs the result. The input RF signal is an RF signal read from the disk. The output of the comparator 100 is transmitted to the low pass filter 110 at the same time as being transmitted to other processing blocks. The low pass filter 110 performs low pass filtering on the output of the comparator 100. The output of the low pass filter 110 is transmitted as the slicing level of the comparator 100.

  The existing optical disk driver converts the RF signal read from the disk through the binarization process shown in FIG. 1 into a binary signal, and the signal converted into the binary signal is transferred to a phase lock loop (PLL). The system clock is applied to reproduce the data read from the disk using the binary signal and the system clock. At this time, there is a slight difference or jitter between the phase of the RF signal and the system clock. 2A to 2C are examples in which jitter occurs between the RF signal from which the offset has been removed and the system clock, and are based on the falling edge of the system clock. In an ideal case, the edge portion of the system clock and the zero crossing point of the RF signal exactly coincide. However, the edge portion of the system clock and the zero point crossing point of the RF signal do not actually coincide with each other, and a slight difference occurs in time. This difference is called jitter.

  Existingly, a jitter value, which is the difference between the RF signal and the system clock, is used to evaluate the quality of the RF signal. That is, in an ideal case, since the zero crossing point of the RF signal is accurately located at the edge of the system clock, the jitter value is hardly measured. However, when noise or an abnormal situation occurs in the RF signal, the zero point crossing of the RF signal cannot be accurately positioned at the edge of the system clock, so that the jitter value is measured. Therefore, the quality of the RF signal can be confirmed based on the measured jitter value.

  However, as the recording density of the disk increases, the magnitude of the RF signal corresponding to a binary signal having a short T (where T is an interval of 1 pit) is gradually decreasing. As a result, in the case of an RF signal corresponding to a short T binary signal, even if a little noise is added, the signal distortion is relatively large, or an incorrect jitter value is located near the zero point. Can be measured. Therefore, the quality of the RF signal read from the high-density disk cannot be evaluated using the jitter value measured based on the difference between the RF signal and the system clock.

  A technical problem to be solved by the present invention is a signal quality evaluation apparatus and method capable of accurately evaluating the quality of an input signal (or reproduction signal or RF signal) regardless of recording density, and an optical disk driver having a signal quality evaluation apparatus. There is to offer.

  Other technical problems to be solved by the present invention include an input signal level value based on the relationship between the input signal and the binary signal of the input signal, and an ideal input signal based on a predefined binary signal. And an optical disk driver having a signal quality evaluation device and a signal quality evaluation device capable of evaluating the quality of an input signal using the above.

  In order to achieve the above-described technical problem, the present invention includes a level value detection unit that detects a level value of the input signal by a binary signal of the input signal, and a plurality of pre-defined levels of the detected level value. An input signal composing unit that configures a plurality of ideal input signals using a binary signal, and a quality arithmetic unit that obtains the quality of the input signal by an arithmetic operation between the plurality of ideal input signals. A signal quality evaluation apparatus is provided.

  In order to achieve the above technical problem, the present invention uses an input signal reproduced from a disc, a binary signal of the input signal, and a plurality of predefined binary signals, from the disc. Provided are a signal quality evaluation device that evaluates the quality of a reproduced input signal, and an optical disk driver that includes a system control unit that corrects a focusing position while finely adjusting a focus offset according to the evaluated quality of the input signal. .

  In order to achieve the above-mentioned technical problem, the present invention uses an input signal reproduced from a disc, a binary signal of the input signal, and a plurality of predefined binary signals to generate the input signal. A signal quality evaluation apparatus for evaluating quality, and a disk drive comprising a system control unit for finely adjusting tilt correction according to the evaluated quality of the input signal.

  In order to achieve the above-mentioned technical problem, the present invention uses an input signal reproduced from a disc, a binary signal of the input signal, and a plurality of predefined binary signals to generate the input signal. An input signal quality evaluation apparatus for evaluating quality, and a disk driver including a system control unit that finely adjusts the detrack offset while changing the detrack offset according to the evaluated quality of the input signal.

  In order to achieve the above-mentioned technical problem, the present invention uses an input signal reproduced from a disc, a binary signal of the input signal, and a plurality of predefined binary signals to generate the input signal. An input signal quality evaluation apparatus for evaluating quality, and a disk driver including a system control unit for finely adjusting recording conditions while changing recording conditions for the disk according to the evaluated quality of the input signal.

  In order to achieve the above-mentioned technical problem, the present invention includes a step of detecting a level value of the input signal by a binary signal of the input signal, and a plurality of binary signals predefined with the detected level value. Are used to construct a plurality of ideal input signals, and to obtain the quality of the input signals by calculating between the plurality of ideal input signals.

  The objects of the present invention are not limited to the objects mentioned above, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 3 is a functional block diagram of the input signal quality evaluation apparatus according to the present invention. Referring to FIG. 3, the input signal quality evaluation apparatus includes a level value detection unit 300, an input signal configuration unit 310, and a quality calculation unit 320.

  The level value detection unit 300 detects a level value of the input signal using a binary signal of the input signal (hereinafter referred to as a binary signal). At this time, the detected level value can be defined as a level value representing the current channel state.

  The level value detection unit 300 classifies the input signal into a plurality of levels based on the binary signal, and detects a level value for the input signal by a method of obtaining an average value for each level. Therefore, the level value detection unit 300 can be configured as shown in FIG. FIG. 4 is a detailed view of the level value detection unit 300 shown in FIG. Referring to FIG. 4, the level value detection unit 300 includes an input signal separation unit 400 and a level value detection unit 440.

  The input signal separation unit 400 separates the input signal into a plurality of levels using the binary signal. For this, the input signal separator 400 includes an input signal processor 410, a binary signal processor 420, and a selection unit 430.

  The input signal processor 410 includes n delay units 410_1 to 410_n. The n delay devices 410_1 to 410_n are for synchronizing the input signal and the binary signal.

The binary signal processor 420 outputs a selection signal combined with the input binary signal. For this purpose, the binary signal processor 420 includes j delay units 421_1 to 421_j and a selection signal generator 422. That is, in the case of FIG. 4, the binary signal processor 420 includes j delay units 421_1 to 421_j, so that the selection signal generator 422 can generate 2 ^{j + 1} selection signals. For example, if the binary signal processor 420 includes two delay devices, select signal generator 422 can generate two ^three selection signals. The 23 selection signals that can be generated are 000, 001, 010, 011, 100, 101, 110, and 111.

  The selection unit 430 selectively transmits the signal output from the input signal processor 410 according to the signal output from the binary signal processor 420. For example, if a “000” value is output from the binary signal processor 420, the selection unit 430 outputs level 0 for the signal output from the input signal processor 410. If the “111” value is output from the binary signal processor 420, the selection unit 430 outputs a level m for the signal output from the input signal processor 410. At this time, level m corresponds to level 7.

  In this way, the input signal level corresponding to the binary signal (one of level 0 to level m) is output from the input signal separation unit 400. At this time, the level output from the input signal separation unit 400 can be regarded as an ideal signal estimation value. The level output from the input signal separation unit 400 is transmitted to the level value detection unit 440.

  The level value detection unit 440 obtains an average value for each level, and detects the obtained average value as the level value of the input signal. For this purpose, the level value detection unit 440 includes m + 1 average value filters 440_0 to 440_m. Therefore, the level value detection unit 440 can be defined as a filter unit. The average value filters 440_1 to 440_m can obtain an average value during a long section with respect to the input level. For example, the average value filters 440_1 to 440_m can obtain the average value for each level according to the equation (1).

Updated level value = previous level value + (delayed input signal−previous level value) / constant (1)
The level value updated by Expression (1) is an average value obtained by each of the average value filters 440_1 to 440_m. In Equation (1), the previous level value is an average value obtained previously by each of the average value filters 440_1 to 440_m, and can be held by each of the average value filters 440_1 to 440_m. The input signal delayed by Expression (1) is a level output from the input signal separation unit 400.

  In Equation (1), the constant can be determined experimentally in consideration of the processing speed of the signal quality evaluation apparatus. That is, as the constant is set to a larger value in Equation (1), the updated level value becomes smaller, and the processing speed of the signal quality evaluation apparatus is generally reduced. The constant may be set to 256, for example. When calculating the average value as in equation (1), if the delayed input signal is the same as the previous level value, the updated level value is the same as the previous level value.

  Further, the average value filters 440_1 to 440_m can be configured to obtain an average value using a low-pass filter.

  The input signal configuration unit 310 configures a plurality of ideal input signals using the level value detected from the level value detection unit 300 and the binary signal defined in advance. The quality calculation unit 320 obtains the quality of the input signal based on the calculation between a plurality of ideal input signals.

  Therefore, the input signal configuration unit 310 and the quality calculation unit 320 can be configured as shown in FIG. FIG. 5 is a detailed diagram of the input signal configuration unit 310 and the quality calculation unit 320 shown in FIG.

  Referring to FIG. 5, the input signal configuration unit 310 includes a first binary table 510, a second binary table 530, a first selector 520, and a second selector 540, and the quality calculation unit 320 is a distance calculator. 550.

  The first and second binary tables 510, 530 have preset binary signals. The first selector 520 selects one of the level values transmitted from the level value detection unit 300 based on the binary signal provided from the first binary table 510, and selects the selected signal as one ideal signal. To the quality calculation unit 320 as a typical input signal. The second selector 540 selects one of the level values transmitted from the level value detection unit 300 based on the binary signal provided from the second binary table 530, and selects the selected signal as the other signal. One ideal input signal is transmitted to the quality calculation unit 320. Thus, the input signal configuration unit 310 configures a plurality of ideal input signals.

  The binary signals provided from the first binary table 510 and the second binary table 530 have different binary signals. This is because a plurality of different input signals are configured in order to measure an error occurring in the input signal. That is, the binary signal provided from the second binary table 530 may be a binary signal shifted by 1 bit with respect to the binary signal provided from the first binary table 510. For example, when the binary signal provided from the first binary table 510 is “0000111”, the binary signal provided from the second binary table 530 may be “0001111”. In addition, the binary signal provided from the second binary table 530 may be a binary signal shifted by 2T with respect to the binary signal provided from the first binary table 510. For example, when the binary signal provided from the first binary table 510 is “00011000”, the binary signal provided from the second binary table 530 may be “00001100”. In addition, the binary signal provided from the second binary table 530 may be a binary signal that is continuously shifted by 2T with respect to the binary signal provided from the first binary table 510. For example, when the binary signal provided from the first binary table 510 is “00011001100”, the binary signal provided from the second binary table 530 may be “00001100110”.

  When the binary signal provided from the first binary table 510 is “0000111” and the binary signal provided from the second binary table 530 is “0001111”, the first selector 520 has a level value of 2. The second selector 540 can select and transmit the level value 3.

  The quality calculation unit 320 includes a distance calculator 550 as shown in FIG. The distance calculator 550 calculates the sum of the squares of the differences between the level values transmitted from the selector 520 and the selector 540 provided in the input signal configuration unit 301, and outputs the calculated sum as the quality of the input signal. it can. Further, the distance calculator 550 can obtain a square root of the sum of squares of differences between the level values transmitted from the selector 520 and the selector 540, and can output the obtained square root as the quality of the input signal. The distance calculator 550 obtains a value obtained by dividing the square root of the sum of the squares of the differences between the level values transmitted from the selector 520 and the selector 540 by the amplitude of the input signal, and inputs the obtained value. Output as signal quality.

The principle of how to obtain signal quality from an ideal input signal will be described as follows. The principle of generating an input signal will be described with a simple example. If a PR (Partial Response) channel is described, the PR (1, 2, 1) channel obtains a signal that has passed through a digital filter having filter coefficients 1, 2, and 1 when a binary signal is input. It means that you can. This will be described with reference to a hardware configuration as shown in FIG. FIG. 6 is a hardware configuration example diagram of the PR (1, 2, 1) channel. At this time, if the input binary signal is assumed to be -1 or 1 so that the DC value becomes 0 for convenience, three binary signals constitute one output, so the number in all cases is taken into account. the number of cases of about 2 ³ if occurs. The output signals at this time are as shown in Table 1.

表１で３番目及び６番目は１Ｔが出る場合であるが、ＢＤ（ブルーレイ ディスク）やＨＤ−ＤＶＤ（Ｈｉｇｈ Ｄｅｆｉｎｉｔｉｏｎ−ＤＶＤ）の場合には、二進信号自体に１Ｔが存在しないため、０という出力は出られない。例えば、入力信号の二進信号が次の通りである時、図６のデジタルフィルタから出力される信号は下記の通りである。

In Table 1, the third and sixth are cases where 1T is output, but in the case of BD (Blu-ray Disc) or HD-DVD (High Definition-DVD), 1T does not exist in the binary signal itself, so 0. There is no output. For example, when the binary signal of the input signal is as follows, the signal output from the digital filter of FIG. 6 is as follows.

Binary signal: -1-1-1-1 + 1 + 1-1-1 + 1 + 1 + 1 + 1 + 1 + 1
Output signal: -4-4-2 + 2 + 2 + 2-2-4-2 + 2 + 4 + 4 + 4 + 4
A graph of the output signal when the binary signal changes from -1 to 1 is as shown in FIG. FIG. 7 is a graph of the output signal when the binary signal changes from −1 to 1. In FIG. 7, a dotted line represents a binary signal, and a solid line represents an output signal. The response characteristic when the binary signal goes from -1 to 1 is generally called a step response. That is, as the binary signal changes, the output signal does not change immediately, but has a response characteristic of about 3 lengths (because it has 3 taps), and has a form characteristic determined by the tap coefficient.

  Generally speaking, ISI (Inter Symbol Interference) is intersymbol interference in the lexicographic sense, but the specific meaning of this is that when the step input is input as shown in FIG. In other words, it means that the length 3 and the deformation corresponding to the shape are affected by the influence of the front and rear signals. Since the ISI is a variable depending on the laser spot shape and the pit length in the case of an optical disc, the length of the ISI is exactly proportional to the storage capacity of the disc in the case of the same spot shape. Then, it is necessary to analyze what distribution the ideal input signal should have when viewed from the viewpoint of obtaining an ideal binary signal in the presence of ISI.

  In order to analyze this, when a binary signal shifted by 1 bit is input to PR (1, 2, 1), the waveform of the output signal is checked. In particular, when the input binary signal is shifted by 1 bit, the output signal of FIG. 6 is also shifted by 1 bit. In this case, in the case of an input signal (output signal of FIG. 6) obtained by an actual circuit, it is located between the signal constituted by the solid line and the signal constituted by the dotted line in FIG. When using PRML (Partial Response Maximum Likely Hood), which is frequently used recently, a signal is determined by checking whether an input signal is actually closer to a dotted line or a solid line.

  At this time, the probability of error occurrence in the distribution of ideal input signals decreases as the distance between the solid line signal and the dotted line signal in FIG. 7 increases. The reason is that the basic principle of PRML is to determine whether the input signal is close to the solid line or the dotted line in FIG. 7, but basically the farther the distance between the solid line waveform and the dotted line waveform in FIG. This is because it is possible to clearly determine which input signal is closer to.

  In general, the Euclidean distance may be obtained as the distance between the two waveforms, and the Euclidean distance may be obtained by adding all the squared signals obtained by subtracting two signals entering every unit time.

For example, in the case shown in FIG. 8, when the distance between both waveforms is obtained, 0.5 ² +1 ² +0.5 ² = 1.5 mm is obtained. This means that as the distance of 1.5 mm increases, the signal becomes easier to distinguish. FIG. 8 is a change diagram of an output waveform when one waveform is shifted by 1 bit with respect to another waveform. Then, an ideal waveform distribution (in other words, a level distribution) in the case of 3 taps can be obtained in the form of PR (a, b, a) in the case of a general 3-tap PR model. And b need the following conditions.

1. a <b (spot distribution condition of optical disc, distribution in which the central part of the spot is larger than the other part of the spot)
2. a + b + a = 1 (general FIR filter condition)
3. a> 0, b> 0
If this condition is specifically described, it can be expressed by a condition of b = 1-2a and a condition of 0 <a <0.5. In this case, Table 1 must be modified as shown in Table 2 below.

図８のような場合に両波形の距離を求めれば、（−２ａ）^２＋（２ｂ）^２＋（２ａ）^２と求めることができる。ここでｂを消去すれば、２４ａ^２−１６ａ＋４に式を簡略化できる。

If the distance between the two waveforms is obtained in the case of FIG. 8, it can be obtained as (−2a) ² + (2b) ² + (2a) ² . If b is deleted here, the equation can be simplified to 24a ² -16a + 4.

According to FIG. 9, when the maximum value is a = 0 with respect to the condition of 0 <a <0.5, the expression 24a ² -16a + 4 has a value of 4, and the minimum value is a = 1/3. , It can be seen that the expression 24a ² -16a + 4 gives a value of 4/3. FIG. 9 is a distance graph of both waveforms according to changes in the a value.

  Therefore, when the 3-tap PR channel is PR (0, 1, 0), the detection performance for the input signal is the best, and when it is PR (1/3, 1/3, 1/3), the detection for the input signal is performed. It turns out that the performance is the worst. If this is analyzed with a level distribution, if the 3-tap PR channel is PR (0, 1, 0), it means that the level distribution of the input signal is exactly the same as an ideal rectangular wave, and the 3-tap PR channel Means that the closer to PR (0, 1, 0), the better the detection rate for the input signal.

  As another example, if PR (1,2,1) and PR (1,8,1) are compared, the Euclidean distance of 1.5 mm in PR (1,2,1) Since 1,8,1) has a Euclidean distance of 1.76 mm, it can be said that PR (1,8,1) has a better detection rate for the input signal. This shows that the performance of PRML becomes more advantageous as the modulation size of 2T becomes larger.

  Accordingly, the level value of the input signal is detected from the binary signal and the input signal through the circuits of FIGS. 4 and 5, and two ideal input signals are configured by the detected level value and the predefined binary signal. Later, we want to determine the distance between two ideal input signals and thereby try to evaluate the quality of the input signals.

  That is, a value called distance can be defined as an example of signal quality. That is, as shown in FIG. 10A and FIG. 10B, an equation for obtaining the distance between two signals that have a difference can be defined as equation (2). FIG. 10A shows the case of PR (1, 2, 1), and FIG. 10B shows the case of PR (1, 8, 1).

式（２）でＲＦ_ｔｒｕｅは、図１０Ａ及び図１０Ｂで実線で図示した波形であり、ＲＦ_{ｆａｌｓｅ}は、図１０Ａ及び図１０Ｂで点線で図示した波形である。式（２）の物理的な意味は図１１Ａ及び図１１Ｂと同じである。図１１Ａは、ＰＲ（１，２，１）の場合であり、図１１Ｂは、ＰＲ（１，８，１）の場合である。式（２）でＮＲＺＩ_{ｄｉｆｆｅｒｅｎｃｅ}は、入力信号を構成する二つの二進信号列のうち他の部分が何ビットであるかを表す数値である。

In Equation (2), RF _true is a waveform illustrated by a solid line in FIGS. 10A and 10B, and RF _false is a waveform illustrated by a dotted line in FIGS. 10A and 10B. The physical meaning of equation (2) is the same as in FIGS. 11A and 11B. FIG. 11A shows the case of PR (1, 2, 1), and FIG. 11B shows the case of PR (1, 8, 1). In Expression (2), NRZI _difference is a numerical value indicating how many bits are in the other parts of the two binary signal sequences constituting the input signal.

  On the other hand, another signal quality evaluation method for obtaining an SNR (Signal Noise Rate) using the level value detection unit 300, an input signal, and a binary signal can be defined as Equation (3).

式（３）は、レベルから得られた信号であるので、便宜上ＬＳＮＲ（Ｌｅｖｅｌ ＳＮＲ）と表現する。ＬＳＮＲ演算に基づいた入力信号品質評価装置は、図１２に示したように構成できる。図１２は、ＬＳＮＲ演算に基づいた入力信号品質評価装置の詳細図であり、入力信号分離部１２００、レベル値検出部１２４０、選択器１２５０及び品質演算器１２６０を備える。

Since the expression (3) is a signal obtained from the level, it is expressed as LSNR (Level SNR) for convenience. The input signal quality evaluation apparatus based on the LSNR calculation can be configured as shown in FIG. FIG. 12 is a detailed diagram of an input signal quality evaluation apparatus based on the LSNR calculation, and includes an input signal separation unit 1200, a level value detection unit 1240, a selector 1250, and a quality calculator 1260.

  The input signal separation unit 1200 has the same configuration as the input signal separation unit 400 shown in FIG. Accordingly, the input signal separation unit 1200 includes an input signal processor 1210 including n delay units 1210_1 to 1210_n, a binary signal processor 1220 including j delay units 1221_1 to 421_j, and a selection signal generator 1222. A selection unit 1230 for selectively transmitting a signal output from the input signal processor 1210 according to a signal output from the base signal processor 1220 is provided.

  The level value detection unit 1240 has the same configuration and operation as the level value detection unit 440 shown in FIG. The selector 1250 selects and transmits one of the level values output from the level value detector 1240 according to the signal output from the binary signal processor 1220.

  The quality calculator 1260 calculates the quality of the input signal based on the LSNR calculation, and outputs the calculated result.

  When the signal quality evaluation apparatus of FIG. 3 and the signal quality evaluation apparatus of FIG. 12 are combined, it is possible to measure the signal quality fairly accurately. That is, when the distance obtained by the quality calculation unit 320 in FIG. 3 and the result calculated by the quality calculator 1260 in FIG. 12 are calculated as in Expression (4), accurate signal quality can be measured.

New parameter = sqrt (distance) * LSNR (4)
Based on equation (4), the quality evaluation unit 320 of FIG. 3 may be combined with the quality evaluation unit 126 of FIG. New parameter in equation (4) can be defined as the estimated signal quality.

  In general, LSNR is an index representing how many noise components appear in an input signal. The larger the value, the better the quality of the input signal, and the distance represents the output characteristics depending on the frequency of the input signal from which the noise component has been removed, so the larger the value, the better the quality of the input signal. means. Therefore, when these two parameters are combined, the quality of the input signal can be measured accurately. FIG. 13A is a relationship diagram between the signal quality by the LSNR calculation and the bit error rate, FIG. 13B is a relationship diagram between the signal quality by the distance and the bit error rate, and FIG. 13C shows the LSNR calculation and the distance calculation. FIG. 6 is a relationship diagram between signal quality and bit error rate when combined. FIG. 13C can measure a more accurate signal quality than FIGS. 13A and 13B.

  Therefore, according to the object of the present invention, the quality calculation unit 320 of FIG. 3 can be modified to determine the quality of the input signal based on the distance and LSNR obtained based on the two ideal signals. Since the distance defined by Equation (2) is the sum of the squares of the differences between the two signals, since the geometric distance average is obtained by converting the average distance only after taking the square root, Equation (4) Is obtained by performing sqrt calculation on the distance.

  In some cases, in order to compensate for the magnitude of the input signal, the work of formalizing the quality of the signal obtained by Equation (4) with the maximum amplitude of the input signal may be used. In this case, equation (4) can be redefined as equation (5).

New parameter = sqrt (distance) * LSNR / input signal amplitude (5)
In equation (5), “New parameter” may be defined as the estimated signal quality.

  In addition, the signal quality evaluation defined in Equation (4) can be defined again as in Equation (6).

信号品質は、２信号間の距離に基づいて式（６）により得られる。すなわち、信号品質を得るために、式（６）のようにノイズ信号の自乗の和が２信号間の距離の和と共に計算される。式（６）のログ（ｌｏｇ）は、ｄＢを表すために使われる概念である。したがって、ログがｄＢを表すために必要でなければ、式（６）で１０ｌｏｇ_１０は削除されうる。式（６）で“Ｎｅｗ ｐａｒａｍｅｔｅｒ”は、評価された信号品質である。

Signal quality is obtained by equation (6) based on the distance between the two signals. That is, in order to obtain signal quality, the sum of squares of noise signals is calculated together with the sum of the distances between the two signals as in equation (6). The log (log) in equation (6) is a concept used to represent dB. Therefore, 10log ₁₀ can be deleted in equation (6) if the log is not needed to represent dB. In equation (6), “New parameter” is the evaluated signal quality.

  Since the signal quality evaluation apparatus according to the present invention has an advantage that the signal quality can be accurately evaluated even in the case of a high-density disk, the quality evaluation value can be obtained by, for example, focus correction, tilt correction, detrack correction, This can be used to optimize recording signals.

  For example, in the focus correction in the optical disk driver, the focus portion having the optimum performance is searched for after the signal quality reproduced from the disc is measured while changing the focus portion desired to be corrected. Therefore, the optical disk driver can be configured as shown in FIG. That is, the optical disk driver 1400 evaluates the quality of the reproduction signal based on the relationship between the reproduction signal picked up from the disk 1401 through the pickup unit 1402 according to the present invention, the binary signal of the reproduction signal, and a plurality of ideal reproduction signals. Signal quality evaluation device 1403 that performs the focus adjustment of the focus drive unit 1404 by adjusting the focus offset of the focus drive unit 1404 in detail based on the evaluation result of the signal quality evaluation device 1403, and the focus control unit 1404 that focuses on the focusing portion having the optimum performance 1405 may be provided. The focusing portion having the optimum performance may be a point where the New parameter of the formula (4) or the formula (5) is maximized. According to the object of the present invention, the optical disk driver 1400 of FIG. 14 can be reconfigured so that the signal quality evaluation device 1403 is provided in the system control unit 1405.

  Tilt correction by an optical disk driver searches for a tilt portion having an optimum performance after measuring a signal quality reproduced while changing a tilt portion desired to be corrected. Therefore, the optical disk driver can be configured as shown in FIG. That is, the optical disk driver 1500 evaluates the quality of the reproduction signal based on the relationship between the reproduction signal picked up from the disk 1501 through the pickup unit 1502 according to the present invention, the binary signal of the reproduction signal, and a plurality of ideal reproduction signals. And a system control unit 1505 for controlling the tilt adjustment unit 1504 according to the evaluation results of the signal quality evaluation device 1503 and finely adjusting the tilt to search for a tilt part having optimum performance. it can. The portion having the optimum performance may be a point where the new parameter of the formula (4) or the formula (5) is maximized. The optical disk driver in FIG. 15 can be reconfigured so that the signal quality evaluation device 1503 is provided in the system control unit 1505.

  In the detrack correction by the optical disk driver, the signal quality is measured while changing the detrack portion desired to be corrected, and the detrack portion having the optimum performance is searched. Therefore, the optical disk driver can be configured as shown in FIG. That is, the optical disk driver 1600 evaluates the quality of the reproduction signal based on the relationship between the reproduction signal picked up from the disk 1601 through the pickup unit 1602 according to the present invention, the binary signal of the reproduction signal, and a plurality of ideal reproduction signals. System control for searching for a detrack portion having optimum performance by controlling the detrack adjustment unit 1604 so that the detrack offset is finely adjusted according to the evaluation result of the signal quality evaluation device 1603 and the signal quality evaluation device 1603 A portion 1605 can be provided. The portion having the optimum performance may be a point where the new parameter of the formula (4) or the formula (5) is maximized. According to the object of the present invention, the optical disk driver 1600 of FIG. 16 can be reconfigured so that the signal quality evaluation device 1603 is provided in the system control unit 1605.

  In order to optimize the recording signal by the optical disk driver, recording is performed while changing the recording condition, the recorded signal is read and the signal quality is measured, and then the recording condition is adjusted to a portion having the optimum performance. Therefore, the optical disk driver can be configured as shown in FIG. That is, the optical disk driver 1700 evaluates the quality of the reproduction signal based on the relationship between the reproduction signal picked up from the disk 1701 through the pickup unit 1702 according to the present invention, the binary signal of the reproduction signal, and a plurality of ideal reproduction signals. And a write strategy waveform generation unit under a recording condition corresponding to a signal having the highest quality among signals reproduced from the disc 1701 while changing a recording condition according to an evaluation result of the signal quality evaluation apparatus 1703. A system control unit 1705 can be provided to control 1704 to generate a recording waveform. The recording condition corresponding to the signal having the highest quality can be a condition in which the New parameter of the equation (4) or the equation (5) is maximized. The optical disk driver in FIG. 17 can be reconfigured so that the signal quality evaluation device 1703 is provided in the system control unit 1705.

  FIG. 18 is an operation flowchart of an input signal quality evaluation method according to another embodiment of the present invention. Referring to FIG. 18, the method according to the present invention detects the level value of the input signal using the binary signal and the input signal, similar to the level value detection unit 300 of FIG. 3 (step 1801). That is, in step 1801, the input signal is separated into a plurality of levels using a binary signal, an average value for each level is obtained for each of the input signals separated into the plurality of levels, and the average value is determined as the level of the input signal. Detect as value.

  Next, a plurality of ideal input signals are constituted by the detected input signal level values and a plurality of predefined binary signals (step 1802). The configuration of a plurality of ideal input signals is similar to that described in the input signal configuration unit 310 of FIG. That is, based on the plurality of binary signals defined in advance, the level value of the input signal detected in step 1801 is selected to configure the plurality of ideal input signals.

  The quality of the input signal is obtained by calculating between a plurality of ideal input signals (step 1803). The calculation between a plurality of ideal input signals for the purposes of the present invention is similar to that described for the quality calculation unit 320 of FIG. Alternatively, a calculation between a plurality of ideal input signals can be performed in a manner similar to a combination of the quality calculation unit 320 of FIG. 3 and the quality calculation unit 1260 of FIG.

  That is, in step 1803, the square root of the sum of the squares of the differences between a plurality of ideal input signals can be obtained, and the obtained square root can be obtained as the quality of the input signal. Alternatively, in step 1803, a value obtained by dividing the square root of the sum of squares of differences between a plurality of ideal input signals by the amplitude of the input signal can be obtained, and the obtained value can be obtained as the quality of the input signal. . Alternatively, the 1803 step further includes a step of calculating an LSNR using the input signal and the binary signal, and calculating a calculation result between the LSNR calculation result and a plurality of ideal input signals to obtain a quality of the input signal. Can be requested.

  Alternatively, the step 1803 further includes a step of calculating an LSNR using an input signal and a binary signal, and a calculation result between a result obtained by formatting the LSNR calculation result with the amplitude of the input signal and a plurality of ideal input signals. The result can be calculated to determine the quality of the input signal.

  The program for performing the signal quality evaluation method according to the present invention can be embodied as a computer readable code on a computer readable recording medium. Computer-readable recording media include all types of storage devices that store data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc., and carrier wave (for example, transmission over the Internet). Including those embodied in form. The computer-readable recording medium may be distributed in a computer system connected to a network, stored as a computer-readable code in a distributed manner, and executed.

  As described above, the present invention can accurately evaluate the quality of the input signal (or reproduction signal or RF signal) regardless of the recording density.

  Also, using the signal quality obtained by the present invention, the present invention is an optical disk driver that can accurately follow the focus offset, an optical disk driver that can accurately follow the tilt, or an optical disk driver that can accurately follow the detrack, or An optical disk driver in which accurate recording conditions can be understood can be provided.

  The present invention has been mainly described with reference to the preferred embodiments. Those skilled in the art will appreciate that the present invention may be embodied in variations that do not depart from the essential characteristics of the invention. Accordingly, the disclosed embodiments should be considered in an illustrative, not a limiting sense. The scope of the present invention is shown not in the foregoing description but in the claims, and all differences within the equivalent scope should be construed as being included in the present invention.

It is a functional block diagram which shows a general binarization process. It is a figure which shows the example of the jitter which generate | occur | produced between RF signal from which offset was removed, and a system clock. It is a figure which shows the example of the jitter which generate | occur | produced between RF signal from which offset was removed, and a system clock. It is a figure which shows the example of the jitter which generate | occur | produced between RF signal from which offset was removed, and a system clock. It is a functional block diagram of the input signal quality evaluation apparatus by one Embodiment of this invention. FIG. 4 is a detailed view of the level value detection unit shown in FIG. 3. FIG. 4 is a detailed view of an input signal configuration unit and a quality calculation unit shown in FIG. 3. It is a hardware structural example figure of PR (1, 2, 1) channel. It is an output graph when the binary signal of an input signal changes from -1 to 1. It is a change figure of an output waveform in case one waveform has the relationship shifted 1 bit with respect to another one waveform. It is a graph which shows the distance between both waveforms by the change of a value. It is a graph which shows the distance between both waveforms in case a 3 tap PR channel is PR (1, 2, 1). It is a graph which shows the distance between both waveforms in case a 3 tap PR channel is PR (1, 8, 1). It is a figure which shows the physical meaning in the case of FIG. 10A. It is a figure which shows the physical meaning in the case of FIG. 10B. FIG. 6 is a detailed view of an input signal quality evaluation apparatus based on LSNR calculation according to still another embodiment of the present invention. It is a correlation diagram by signal quality. It is a correlation diagram by signal quality. It is a correlation diagram by signal quality. It is an example of the functional block diagram of the optical disk driver by embodiment of this invention. It is another example of the functional block diagram of the optical disk driver by other embodiment of this invention. It is another example of the functional block diagram of the optical disk driver by other embodiment of this invention. It is another example of the functional block diagram of the optical disk driver by other embodiment of this invention. 4 is an operation flowchart of an input signal quality evaluation method according to an embodiment of the present invention.

Claims (34)

A level value detection unit for detecting a level value of the input signal by a binary signal of the input signal;
An input signal configuration unit that configures a plurality of ideal input signals using the detected level values and a plurality of predefined binary signals;
A signal quality evaluation apparatus comprising: a quality calculation unit that obtains the quality of the input signal by calculation between the plurality of ideal input signals. The level value detection unit includes:
An input signal separation unit for separating the input signal into a plurality of levels using the binary signal;
The signal quality evaluation apparatus according to claim 1, further comprising: a level value detection unit that obtains an average value for each of the input signals separated into the plurality of levels and detects the average value as a level value of the input signal. .   The input signal separation unit includes one or more delay units that delay the input signal to synchronize the input signal and the binary signal before separating the input signal into the plurality of levels. The signal quality evaluation apparatus according to claim 2.   3. The signal quality evaluation apparatus according to claim 2, wherein the level value detection unit obtains the average value using a low-pass filter. The level value detection unit obtains the average value based on the following formula,
Updated level value = previous level value + (delayed input signal−previous level value) / constant The level value updated in the above formula corresponds to the average value, and the previous level value corresponds to the average value obtained previously. The signal quality evaluation apparatus according to claim 2, wherein: The input signal configuration unit is:
The signal quality evaluation apparatus according to claim 1, comprising a plurality of binary tables having the binary signals defined in advance. The input signal configuration unit is:
A plurality of level values are selected from the level values detected from the level value detection unit according to predefined binary signals of the plurality of binary tables and transmitted as the plurality of ideal input signals. The signal quality evaluation apparatus according to claim 6, further comprising a plurality of selectors.   The plurality of binary tables include a first binary table that outputs a first binary signal of the predefined binary signal, and the predefined binary table different from the first binary signal. The signal quality evaluation apparatus according to claim 7, further comprising a second binary table that outputs a second binary signal of the signal.   The quality calculation unit calculates a sum of squares of differences between a plurality of level values transmitted from the plurality of selectors, and outputs the obtained sum as a quality of the input signal. Item 8. The signal quality evaluation apparatus according to Item 7.   The quality calculation unit calculates a square root of a sum of squares of differences between a plurality of level values transmitted from the plurality of selectors, and outputs the obtained square root as a quality of the input signal. The signal quality evaluation apparatus according to claim 7, wherein the apparatus is a signal quality evaluation apparatus.   The quality calculation unit obtains a value obtained by dividing a square root of a sum of squares of differences between a plurality of level values transmitted from the plurality of selectors by an amplitude of the input signal, and the obtained value is input to the input unit. 8. The signal quality evaluation apparatus according to claim 7, wherein the signal quality evaluation apparatus outputs the signal quality.   2. The signal according to claim 1, wherein the quality calculation unit calculates a level signal-to-noise ratio (LSNR) using the input signal and a binary signal, and causes a higher value of the LSNR to correspond to a better signal quality. Quality evaluation device. The signal quality evaluation apparatus according to claim 12, wherein the quality calculation unit calculates the LSNR by performing the following mathematical formula:

  13. The signal quality evaluation apparatus according to claim 12, wherein the quality calculation unit calculates the quality of the input signal by calculating the calculated LSNR and the calculation between the plurality of ideal input signals. . The quality calculation unit performs the following mathematical formula to obtain the quality of the input signal,
New parameter = sqrt (distance) * LSNR
15. The signal quality evaluation apparatus according to claim 14, wherein New parameter corresponds to the quality of the input signal, and the distance corresponds to a distance between two ideal input signals.   The quality calculation unit obtains the quality of the input signal by performing the calculation between the plurality of ideal input signals and calculating the LSNR standardization result for the amplitude of the input signal. The signal quality evaluation apparatus according to claim 12. The quality calculation unit performs the following mathematical formula to obtain the quality of the input signal,
New parameter = sqrt (distance) * LSNR / Amplitude of input signal In the above formula, New parameter corresponds to the quality of the input signal, and distance corresponds to the distance between two ideal input signals. The signal quality evaluation apparatus according to claim 16. The quality calculation unit performs the following mathematical formula to obtain the quality of the input signal,

The signal quality evaluation apparatus according to claim 1, wherein New parameter corresponds to the quality of the input signal, and distance corresponds to a distance between two ideal input signals. Detecting a level value of the input signal by a binary signal of the input signal;
Configuring a plurality of ideal input signals using the detected level values and a plurality of predefined binary signals;
Obtaining a quality of the input signal by calculating between the plurality of ideal input signals. The level value detecting step includes
Separating the input signal into a plurality of levels using the binary signal;
Obtaining an average value for each level for each of the input signals,
The signal quality evaluation method according to claim 19, wherein the average value is a level value of the input signal.   The signal quality evaluation according to claim 19, wherein the input signal configuration step configures the plurality of ideal input signals by selecting the level value according to the predefined binary signal. Method.   The step of obtaining the quality of the input signal comprises obtaining a sum of squares of differences between the plurality of ideal input signals, and outputting the obtained sum as the quality of the input signal. Signal quality evaluation method described in 1.   The step of obtaining the quality of the input signal includes obtaining a square root of a sum of squares of differences between the plurality of ideal input signals, and outputting the obtained square root as the quality of the input signal. The signal quality evaluation method according to claim 19.   The step of obtaining the quality of the input signal obtains a value obtained by dividing the square root of the sum of the squares of the differences between the plurality of ideal input signals by the amplitude of the input signal, and obtaining the obtained value as the input signal. The signal quality evaluation method according to claim 19, wherein the signal quality is output as the quality of the signal.   The step of obtaining the quality of the input signal includes a step of calculating an LSNR using the input signal and a binary signal, and a higher value of the LSNR corresponds to a better signal quality. The signal quality evaluation method described. Determining the quality of the input signal comprises:
26. The signal quality evaluation method according to claim 25, further comprising a step of calculating the calculated LSNR and an operation between the plurality of ideal input signals.   26. The step of obtaining the quality of the input signal further includes a step of performing an operation on the calculation result between the plurality of ideal input signals and the LSNR standardization result with respect to the amplitude of the input signal. Signal quality evaluation method. Determining the quality of the input signal comprises:
Including the step of performing the following formula:

20. The signal quality evaluation method according to claim 19, wherein the distance corresponds to a distance between two ideal input signals.   A computer-readable recording medium encoded by the method according to claim 19 and embodied by a computer. A signal quality evaluation device for evaluating the quality of an input signal reproduced from an optical disc regardless of the recording density of the optical disc;
An optical disk driver comprising: a system control unit that adjusts the conditions while changing the conditions for recording and / or reproducing data to / from the optical disk according to the quality of the input signal. The signal quality evaluation device
A level value detection unit for detecting a level value of the input signal by a binary signal of the input signal;
An input signal configuration unit that configures a plurality of ideal input signals using a plurality of predefined binary signals and the level values;
The optical disk driver according to claim 30, further comprising: a quality calculation unit that calculates quality of the input signal by calculation between the plurality of ideal input signals.   The optical disk driver according to claim 30, wherein the system control unit corrects the focusing position while finely adjusting a focus offset according to the quality of the input signal.   The optical disk driver according to claim 30, wherein the system control unit finely adjusts the tilt correction according to the quality of the input signal.   The optical disk driver according to claim 30, wherein the system control unit finely adjusts a detrack offset according to the quality of the input signal.

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