WO2005031743A1 - 評価装置および評価方法 - Google Patents
評価装置および評価方法Info
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- WO2005031743A1 WO2005031743A1 PCT/JP2004/014711 JP2004014711W WO2005031743A1 WO 2005031743 A1 WO2005031743 A1 WO 2005031743A1 JP 2004014711 W JP2004014711 W JP 2004014711W WO 2005031743 A1 WO2005031743 A1 WO 2005031743A1
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- signal
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- 238000000034 method Methods 0.000 title description 15
- 238000011156 evaluation Methods 0.000 claims description 39
- 238000007476 Maximum Likelihood Methods 0.000 claims description 22
- 238000001914 filtration Methods 0.000 claims description 4
- 230000003044 adaptive effect Effects 0.000 description 15
- 238000010586 diagram Methods 0.000 description 11
- 230000007704 transition Effects 0.000 description 11
- 230000001276 controlling effect Effects 0.000 description 10
- 238000013441 quality evaluation Methods 0.000 description 10
- 230000003287 optical effect Effects 0.000 description 8
- 230000008859 change Effects 0.000 description 5
- 238000012854 evaluation process Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000013459 approach Methods 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/10009—Improvement or modification of read or write signals
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/10009—Improvement or modification of read or write signals
- G11B20/10046—Improvement or modification of read or write signals filtering or equalising, e.g. setting the tap weights of an FIR filter
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/10009—Improvement or modification of read or write signals
- G11B20/10046—Improvement or modification of read or write signals filtering or equalising, e.g. setting the tap weights of an FIR filter
- G11B20/10055—Improvement or modification of read or write signals filtering or equalising, e.g. setting the tap weights of an FIR filter using partial response filtering when writing the signal to the medium or reading it therefrom
- G11B20/10111—Improvement or modification of read or write signals filtering or equalising, e.g. setting the tap weights of an FIR filter using partial response filtering when writing the signal to the medium or reading it therefrom partial response PR(1,2,2,1)
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/10009—Improvement or modification of read or write signals
- G11B20/10481—Improvement or modification of read or write signals optimisation methods
Definitions
- the present invention relates to signal processing for decoding original digital information recorded on a recording medium by a maximum likelihood decoding method, and in particular, optimally demodulates a signal based on signal quality evaluation.
- a signal has been used as an index value for evaluating the quality of a reproduced signal.
- the correlation between the error and the error is not so much in the case of jitter.
- the index value DMSAM d--Minimum Sueed Amplitude UdeMargin: DMS AM is described in detail later.
- FIG. 11 shows a configuration of a conventional reproduction signal quality evaluation device 400.
- the reproduction signal quality evaluation device 400 is disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. Hei 10-21651 (p. 6, FIG. 6)).
- the playback signal quality evaluation device 400 is used as an index for evaluating the quality of the playback signal
- the reproduction signal quality evaluation device 400 includes a data generator 1101 for generating data, a recording / reproduction device 1102 for recording / reproducing data, and a maximum likelihood decoder for performing maximum likelihood decoding on reproduced data and demodulating a data sequence. 1103, a sync pattern detector 1104 for detecting a sync pattern from the demodulated data sequence, and a recording state detection for detecting a data sequence having a path having a minimum distance from the detected data pattern. An output unit 1105, a standard deviation calculator 1106, and a minimum value judgment unit 1107 are provided.
- the standard deviation calculator 1106 calculates the difference between the selected path and the selected path when the data sequence having the path with the minimum Euclidean distance is demodulated by the maximum likelihood decoder 1103; Calculate ( ⁇ —Am) / (_ ⁇ ) based on the standard deviation of ( ⁇ —Am) and the average of the difference between the selected path and the unselected path (— ⁇ ).
- the minimum value determiner 1107 determines the minimum value of ( ⁇ -Am) / ( ⁇ _ Am). ( ⁇ - ⁇ ) / (_ ⁇ ) indicates the quality of the reproduced signal.
- Maximum likelihood decoder 1103 includes an adaptive equalization filter.
- the adaptive equalization filter usually consists of a FIR filter to remove the linear distortion contained in the reproduced signal.
- the adaptive equalization filter filters the signal so that the distortion of the reproduced signal is minimized even when the reproduction state of the recording / reproducing apparatus changes.
- the adaptive method of the adaptive equalization filter is, for example, the LMS method (LeastMeanSquare method).
- the LMS method updates the filter coefficient based on the error between the output of the adaptive equalization filter and the target value.
- the LMS method is widely used because of its simple algorithm and good convergence characteristics.
- the output of the adaptive equalization filter diverges.
- the adaptive equalization filter of the reproduction signal quality evaluation device 400 corrects the output of the adaptive equalization filter even when the recording medium has a large individual difference. For this reason, DMS AM cannot be used as an index for evaluating the signal quality of a recording medium.
- the present invention has been made in view of the above problems, and has an evaluation device and an evaluation method for constructing a stable demodulation system by limiting a control range of a fill-in characteristic (tap coefficient) of a digital filter, and a recording method.
- An evaluation device is an evaluation device including a digital filter, wherein the digital filter filters a signal in accordance with a tap coefficient of the digital filter, and the evaluation device includes: Detecting means for detecting an index for evaluating the quality of the signal based on the obtained signal, and a value of the detected index includes an optimal value of the index, and The digital filter further includes control means for controlling the tap coefficient, whereby the object is achieved.
- the digital filter includes a plurality of taps, and the control unit controls the plurality of tap coefficients so that the plurality of tap coefficients of the plurality of taps have symmetry. Is also good.
- the evaluation device further includes a maximum likelihood decoding unit that performs a maximum likelihood decoding on the filtered signal and generates a binary signal indicating a result of the maximum likelihood decoding. Detecting the index based on the binarized signal, the digital filter includes a first tap, a second tap, a third tap, a fourth tap, and a fifth tap, and the control unit includes:
- the tap coefficient k of the first tap When a tap coefficient 1 ⁇ of the second tap, and the tap coefficients k 2 of the third tap, the tap coefficients k 3 of the fourth tap, even by controlling the tap coefficients k 4 of the fifth tap Good.
- r indicates the frequency characteristic of the digital filter.
- An evaluation method includes: a step of filtering a signal in accordance with a tap coefficient of a digital filter; and a step of detecting an index for evaluating the quality of the signal based on the filtered signal. And controlling the tap coefficient of the digital filter within a predetermined range so that the detected index includes an optimum value of the index, whereby the object is achieved.
- FIG. 1 is a diagram showing a configuration of a reproducing apparatus 100 according to Embodiment 1 of the present invention.
- Figure 2 is a diagram showing the state transitions of the modulation code RLL ( ⁇ , 7) and PR (1, 2, 2, 1).
- FIG. 3 is a diagram showing a configuration of the video decoder 110.
- FIG. 4 is a diagram showing a configuration of the DMSAM detector 111.
- FIG. 5 is a diagram showing a configuration of the FIR filter 108.
- FIG. 6 is a diagram illustrating filter characteristics of the FIR filter 108 on the z-plane.
- FIG. 7 is a diagram showing the relationship between the filter characteristics of the FIR filter 108 and the values of DMSAM.
- FIG. 8 is a diagram showing the frequency characteristics of the FIR filter 108.
- FIG. 9 is a diagram illustrating a configuration of a reproducing apparatus 200 according to Embodiment 2 of the present invention.
- FIG. 10 is a diagram illustrating a configuration of an FIR filter 901.
- FIG. 11 is a diagram showing a configuration of a conventional reproduction signal quality evaluation device 400.
- FIG. 1 shows a configuration of a reproducing apparatus 100 according to Embodiment 1 of the present invention.
- the playback device 100 is configured to allow the optical disc 101 to be inserted.
- the playback device 100 detects the light reflected on the optical disc 101 by dividing the light into four.
- a PIN diode 102 a preamplifier 103 that adds reflected light detected by dividing into four, a high-pass filter 104 with a cutoff frequency of 10 kHz, a Butterworth low-pass filter 105 with a cutoff frequency of 30 MHz, and an evaluation device 150 Including.
- the evaluation device 150 has a variable gain amplifier 106 that adjusts the amplitude of the analog signal, an AZD converter 107 that digitizes the analog signal, and a digital signal that is filtered according to the tap coefficient to correct the distortion of the digital signal.
- a DMSAM detector 111 that detects a DMSAM value based on the evening signal and the binarized signal, and a FIR within a predetermined range so that the DMSAM value includes the optimal value of the DMSAM.
- a coefficient controller 112 for controlling the tap coefficient of the filter 108.
- the DMSAM detector 111 detects a DMSAM based on a metric difference between a plurality of specific paths.
- the coefficient controller 112 controls the coefficient of the FIR filter 108 so that the value of DMS AM is minimized.
- Embodiment 1 of the present invention using RLL (1, 7) modulation as a recording modulation method and equalizing the transmission path of reproduction to PR (1, 2, 2, 1)
- the operation of the reproducing apparatus 100 in the form of performing PR + Viterbi decoding will be described.
- Light reflected by the optical disk 101 is detected by the PIN diode 102.
- the reflected light is divided into four and detected for focus control and tracking control (a focus / tracking control system is not shown), and the PIN diode 102 generates four types of signals.
- the four types of signals are added by the preamplifier 103 and amplified to a desired level.
- the high-pass filter 104 removes low-frequency noise from the output of the pre-amplifier 103, and the low-pass filter 105 removes high-frequency noise from the output of the pre-amplifier 103.
- the variable gain amplifier 106 controls the signal from which noise has been removed to an appropriate level, and the 8/0 converter 107 converts the output (analog signal) of the variable gain amplifier 106 into a digital signal.
- the digital signal has a digital value (sampling value y;).
- FIR filter 108 equalizes the digital signal. The details of the FIR filter 108 will be described later.
- the PLL 109 detects a zero cross point of the equalized digital signal and generates a clock synchronized with the channel clock. Viterbi decoder 110 demodulates the equalized digital signal.
- Figure 2 shows the state transition of the modulation codes RLL (1, 7) and PR (1, 2, 2, 1).
- Sn (a, b, c) represents the n-th state.
- Arguments a, b, and c are the 3-bit input demodulated data before the n-th state.
- the target value I j is a value that can be taken when the sampling value y k makes a state transition from n to n + 1
- the value d is a demodulated data value determined by the sampling value.
- FIG. 3 shows the configuration of the Viterbi decoder 110.
- the Viterbi decoder 110 consists of a branch metric calculator 201 and an ACS block. (Add Comp are elect block) 202, path metric memory 203, and path memory 204.
- Viterbi decoder 110 The operation of the Viterbi decoder 110 will be described with reference to FIG. 2 and FIG.
- the branch metric calculator 201 calculates a branch metric according to Equation 4.
- BM k (j) indicates the k-th branch metric.
- ACS block 202 selects the most likely path according to Equation 5.
- the value in the path memory 204 is updated based on the values of the paths PSS 0 to PSS 3 selected by the ACS block 202.
- the surviving path in the path memory 204 is demodulated as the maximum likelihood path.
- FIG. 4 shows the configuration of the DM SAM detector 111.
- the DM SAM detector 111 includes a delay unit 401 that delays the sampled signal yi by a certain amount to detect a difference in path metric, Metric difference detector 402 that detects a metric difference with the metric of the metric, a pattern detector 403 that detects a pattern that minimizes the Euclid distance, and a metric difference detector 402 that detects the metric difference detected by the metric difference detector 402.
- a variance calculator 404 for calculating the variance, and an average target difference detector 405 for calculating the difference between the average value of the metric differences and the target value are included.
- the DMSAM is an index based on the filtered signal and the binarized signal.
- the DMSAM detector 111 detects a recording sequence in which a path having the minimum Euclidean distance in the maximum likelihood decoding exists, and does not select the metric of the path selected when demodulating the detected reproduced signal sequence by the maximum likelihood decoder. The difference between the metric of the path and the metric difference is calculated, and the variance of the metric difference is calculated to obtain the DMSAM.
- the state detector 404 detects a pattern with the minimum Euclidean distance based on the signal decoded by the Viterbi decoder 110 and converted into a binary signal (see Equation 9).
- the metric difference detector 402 detects a metric difference between the metric of the selected path and the metric of the non-selected path of the pattern having the minimum Euclidean distance, based on the detected pattern. At this time, a delay of a fixed time occurs in demodulation in the Viterbi decoder 110, so that the delay unit 401 delays the sampled signal yi for a fixed time.
- the metric difference detector 402 calculates a metric difference DSAMV between the metric of the selected path and the metric of the non-selected path according to Equation 7.
- (yi-IA;) indicates the branch metric of the path A
- (Yi-IBi) indicates the branch metric of the path B.
- Variance calculating unit 404 the minimum output of the metric difference detector 402 (DSAMV) - based on the Kuritsudo distance d mi n, according to equation 12 to calculate the DMSAM. (Equation 9)
- the value of DMSAM is greatly affected by the coefficient of the FIR filter. Therefore, in the embodiment in which the FIR filter is configured by an adaptive filter according to the LMS algorithm, there is a problem that when an abnormal signal is input to the FIR filter, the output of the adaptive filter is diverged. Also, the filter characteristics of the FIR filter composed of the adaptive filter change over a very wide range as the filter coefficient changes. Therefore, the conventional reproduction quality evaluation device 400 can correct the output of the adaptive equalization filter even when the individual difference of the optical disk is large. As a result, there has been a problem that DM SAM cannot be used as an index for evaluating the signal quality of an optical disc that requires constant characteristics.
- variable range of the filter characteristic (tap coefficient) of the FIR filter 108 is limited, and the equalization that minimizes the value of DMSAM is performed. It can be performed.
- FIG. 5 shows the configuration of the FIR filter 108.
- FIG. 6 shows the filter characteristics of the FIR filter 108 on the z plane.
- FIR filter 108 has five taps. In a normal FIR filter, five tap coefficients of five taps can be freely set, so that filters having various characteristics can be configured. If the degree of freedom of the tap coefficient can be limited, an FIR filter that operates within a certain range can be realized and the stability will increase, and the characteristics of the FIR filter will be predictable. DMS AM can be used.
- the degree of freedom of the filter characteristic is limited in the FIR filter 108, and the FIR filter 108 satisfies the characteristic that the DMSAM has the same value as the adaptive FIR filter.
- FIR filter for processing reproduced signals without distortion The group delay of 108 is desirably flat, and the FIR filter 108 has a symmetrical tap coefficient so that it is not affected by nonlinear distortion of the light beam traveling direction caused by recording conditions. desirable. Due to constraints (symmetrical taps coefficients), five tap coefficients of the FIR filter 1 0 8 (k G, k have k 2, k 3, k 4) is three tap coefficients (k 0, k 2 ) become.
- Equation 10 When the degree of freedom of the tap coefficient is changed from 5 to 3, and the filter characteristics of the FIR filter 108 that satisfies the constraint condition are expanded on the Z plane, the complex conjugate solution with the radius S at the position of radius r and 1 / r at angle S Is placed (see Fig. 6). If the solution on the Z plane is ⁇ , ⁇ , ⁇ , then ⁇ , HI ', ⁇ , ⁇ , are expressed by Equation 10:
- the tap coefficient of the FIR filter 108 is calculated based on Equations 10 and 11 (see Equation 12).
- the tap coefficients of the FIR filter 108 can be represented by two variables (r, ⁇ ) by the above constraint conditions, and the degree of freedom can be reduced to two.
- FIG. 7 shows the relationship between the filter characteristics of FIR filter 108 and the value of DMS AM.
- the horizontal axis shows the value r, and the vertical axis shows the value 0.
- the NA of the reproducing apparatus 100 is 0.85, and the wavelength of the light beam is 405 nm.
- the optimal FIR filter is constructed as the playback condition. I have. At this time, the DM SAM value was 7.9%, and the FIR filter according to the conventional LMS method was 8.2%.
- the FIR filter 108 according to the first embodiment of the present invention has better filter characteristics than the conventional FIR filter. This means that while the conventional FIR filter adapts the reproduction level to the desired value for all patterns, the FIR filter 108 changes the filter characteristics so that the DMS AM value is minimized. It is caused by doing. Conventionally, all playback levels are re-set to the desired value.
- Embodiment 1 of the present invention detects only the pattern with the shortest Euclidean separation (that is, the pattern in which error is most likely to occur). The characteristics of the FIR filter 108 are adjusted so that the reproduced signal of this pattern has a desired value. That is, in the first embodiment of the present invention, since the characteristics of FIR filter 108 are optimized only for a pattern that easily causes an error, a reproduction system with less errors can be realized.
- the characteristics of the FIR filter 108 can be determined by controlling only the value r.
- a sufficiently low DMSAM can be realized despite the fact that the degree of freedom of the FIR filter 108 is greatly limited. It is more desirable that the value r be in the range of 0.21 ⁇ r ⁇ 0.27 at which the value of DMSAM is 9% or less (see FIG. 7).
- FIG. 8 shows a frequency characteristic of the FIR filter 108.
- the horizontal axis indicates the normalized frequency of the FIR filter 108.
- FIR Phil Evening Black The lock frequencies 1 and 2 are represented by 1.
- the vertical axis indicates the amplitude [dB].
- the coefficient controller 112 controls the tap coefficient so that 0.21 ⁇ r ⁇ 0.27 is satisfied, so that the value of DMSAM is minimized.
- the characteristics of the FIR filter 108 do not significantly change. Therefore, stable operation can be performed against defects and the like. While limiting the characteristic variable range of the FIR filter 108 to a narrow region, a DMSAM value having better characteristics than the conventional FIR filter can be obtained. As a result, according to the reproducing apparatus 100 of the first embodiment of the present invention, it is possible to evaluate the signal quality of a recording medium that requires constant characteristics.
- the reproducing apparatus 100 according to the first embodiment of the present invention has been described above with reference to FIGS.
- Embodiment 1 of the present invention in FIR filter 108 having a constant group delay and a target filter coefficient, a predetermined range is set so that the value of DM SAM includes the optimal value of DM SAM.
- the filter coefficient of the FIR filter 108 was controlled within.
- the control range of the filter coefficient of the FIR filter is The control is performed by the conventional LMS method, and the control range of the filter coefficient is limited to a predetermined range.
- FIG. 9 shows a configuration of a reproducing apparatus 200 according to Embodiment 2 of the present invention. 9, the same components as those of the playback apparatus 100 shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.
- the playback device 200 is configured so that the optical disc 101 can be inserted.
- the reproducing apparatus 200 includes a PIN diode 102, a preamplifier 103, a high-pass filter 104, a butter-mouth single-pass filter 105, and an evaluation device 250.
- the evaluation device 250 includes a variable gain amplifier 106, an A / D converter 107, an FIR filter 901, a PLL 109, a Viterbi decoder 110, a DMSAM detector 111, an LMS controller 902, and a tap coefficient limiter 903.
- FIG. 10 shows a configuration of the FIR filter 901.
- FIR fill 901 has five taps. 5 taps of the FIR filter 901 has tap coefficients (k., K x, k 2, k 3, k 4).
- the LMS controller 902 controls the tap coefficients (k 0 , k x k 2 , k 3 , k 4) of the FIR filter 901 by the LMS method so as to minimize the DM SAM value detected by the DM SAM detector 111. ) Control. That, LMS controller 902, tap coefficients of the FIR full I le evening 901 (k., K 2, k 3, k 4) successively updates the.
- the LMS controller 902 controls the tap coefficient of the FIR filter 901 appropriately,
- the setup coefficient is determined so that the DMS AM value is minimized. Advance by performing reproduction of signals in the proper state, such that the output of the FIR filter 901 is appropriately converged, can determine the tap coefficient (k., K have k 2, k 3, k 4 ).
- a signal reproduced in a stress state assumed at the time of operation of the drive is given to the FIR filter 901 in advance, and the range of the tap coefficient (ko, k k 2 , k 3 , k 4 ) Ask for.
- stress can occur during drive operation. Defocus and the variation of the spherical inclination of the disk. In addition, changes in power and strategy during recording are also stresses.
- control range of the tap coefficients to operate the pre-LMS controller 9 0 2 (k., K 2, k 3, k 4).
- the control range of the tap coefficients can be easily determined by preliminary experiments during drive design.
- Tap coefficient limiter 9 0 3 limits Tatsu flop coefficient control range of the tap coefficients determined by prior experimentation (k., K have k 2, k 3, k 4 ). Therefore, the fill characteristics of the FIR fill 901 do not significantly change from the fluctuation range assumed in the design stage in advance. As a result, the reproducing apparatus 200 can operate stably against a defect or the like.
- the reproducing apparatus 200 according to the second embodiment of the present invention limits the optimum value of the DM SAM while limiting the filter characteristic variable range of the FIR filter 901 to a predetermined range, similarly to the reproducing apparatus 100. Obtainable. Therefore, the reproducing apparatus 200 according to Embodiment 2 of the present invention can evaluate the signal quality.
- the evaluation device 150 or the evaluation device 250 corresponds to the “evaluation device having a digital filter”
- the filter 901 corresponds to a “filter for filtering a signal according to a tap coefficient”
- the DMSAM detector 111 corresponds to a “filter for evaluating signal quality based on a filtered signal”.
- ⁇ detection means for detecting indices '' the coefficient controller 1 12 or LMS controller 9 02 and tap coefficient limiter 9 0 3 ⁇ make sure that the detected index value contains the optimal value of the index.
- the optical disc device of the present invention is not limited to the one shown in FIG.
- An optical disk device having an arbitrary configuration can be included in the scope of the present invention as long as the functions of the above-described units are achieved.
- the index for evaluating signal quality is not limited to DMSAM.
- Other indicators may be used as long as the indicators can evaluate the signal quality.
- Other indices are, for example, SAM (Seuenced Amplitude Maegin) and SAMER (Seuenced Amplitude Maegin Error).
- SAM represents the difference (metric difference) between the metric of the selected path and the metric of the unselected / selected path in the Viterbi decoder. The higher the SAM value, the better the playback signal.
- SAMER indicates the number of metric differences where the difference (metric difference) between the metric of the selected path and the metric of the non-rejected path in the Viterbi decoder is equal to or less than a preset threshold. The smaller the value of SAMER, the better the playback signal.
- the reproducing apparatus 100 includes an S ⁇ M detector in addition to or instead of the DMSAM detector 111.
- the SAM detector detects the difference between the metric of the selected path and the metric of the unselected path in the Viterbi decoder.
- a SAMER detector is provided in addition to the reproducing apparatus 100 or the DMSAM detector 111 or in place of the DMS AM detector 111.
- the SAMER detector detects the difference between the metric of the selected path and the metric of the non-selected path in the Viterbi decoder, and counts the number of differences where the detection result is equal to or less than a preset threshold.
- the conventional reproduction signal quality evaluation device 400 controls the amplitude of the reproduction signal so that the amplitude of the reproduction signal becomes a predetermined constant level.
- this control is not necessarily the control of the amplitude to minimize the DMSAM.
- the reproducing apparatus 100 may control the amplitude of the reproduced signal so that the DMSAM value approaches the optimal value of the DMSAM.
- FIG. 1 FIG. 1
- FIG. 4 and FIG. 9 a reproducing apparatus 10 according to an embodiment of the present invention will be described.
- An example in which 0 and the playback device 200 control the amplitude of the playback signal so that the DMSAM value is minimized will be described.
- the DMSAM detector 111 includes a dispersion calculator for calculating DMSAM, which is a variance of DMSAMV, and a target error calculator 405 for calculating the average value of DMS AMV and the difference between d m and n .
- the average target difference calculator 405 detects the difference between the DMSAMV average and d min .
- the average target difference calculator 405 outputs an error signal indicating the detected difference (error) to the variable gain amplifier 106.
- the variable gain amplifier 106 controls the amplitude of the reproduced signal so that the DM SAM value approaches the optimal value of DMSAM. For example, variable gain amplifier 106, the average value of DMSAMV is closer to d mi n, controls the amplitude of the reproduced signal. Accordingly, since the average value of the DM SAM V becomes equal to d min , the amplitude control can be performed so that the DMSAM becomes the maximum] compared to the conventional amplitude control.
- the amplitude control of the present invention improves the DM SAM value by about 1% over the conventional amplitude control.
- the reproduction device 100 is configured to control the output of the DMSAM detector.
- the amplitude of the reproduction signal is controlled based on the difference between the average values of the above, the control example of the amplitude of the reproduction signal is not limited to this. Control of the amplitude of the reproduced signal can be realized by AGC processing using the reproduced signal itself, or by digitally multiplying the sampling point after A / D conversion by a coefficient to make the amplitude uniform.
- each means described in the embodiment shown in FIGS. 1 and 9 may be realized by hardware, may be realized by software, or may be realized by hardware and software. Is also good.
- the evaluation processing of the present invention can be executed regardless of whether it is realized by hardware, software, or by hardware and software.
- the evaluation processing of the present invention includes a “step of filtering a signal according to a tap coefficient of a digital filter” and a “step of detecting an index for evaluating the quality of a signal based on a filtered signal”. And “controlling the evening filter coefficient of the digital filter within a predetermined range so that the detected indicator includes the optimum value of the indicator”.
- the evaluation process of the present invention may have any procedure as long as the above-described steps can be executed.
- the evaluation device of the present invention may store an evaluation processing program for executing a function of the evaluation device.
- the evaluation processing program may be stored in advance in a storage unit included in the evaluation device when the computer is shipped.
- the access process may be stored in the storage unit after the computer is shipped.
- the user may download the evaluation process from a specific website on the Internet for a fee or free of charge, and install the downloaded program on a computer.
- the evaluation process is recorded on a computer-readable recording medium such as a flexible disk, CD-ROM, DVD-ROM, etc., the evaluation process may be installed in the computer using the input device. Good.
- the installed evaluation process is stored in the storage unit.
- Item 1 An evaluation device for evaluating signal quality
- Maximum likelihood decoding means for performing maximum likelihood decoding on the signal and generating a binary signal indicating a result of the maximum likelihood decoding
- Detecting means for detecting an index for evaluating the quality of the signal based on the signal and the binarized signal
- Amplitude control means for controlling the amplitude of the signal so that the value of the detected index approaches the optimal value of the index
- Evaluation method including:
- the DMS AM value can be minimized to the same extent as when decoding is performed by an adaptive equality filter using a conventional LMS without greatly changing the characteristics of the FIR filter. I can do it.
- ADVANTAGE OF THE INVENTION it is possible to limit the characteristics of a signal equalizer, which is pre-processing for Viterbi decoding, within a predetermined fixed range, and evaluate the signal of a recording medium that could not be used conventionally. DMS AM can be used. Further, in the reproducing apparatus of the present invention, since the adaptation range of the signal equalizer can be limited to a constant value, it is necessary to configure a stable demodulation system even when a signal is lost due to a defect of a recording medium or the like. Can be.
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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US10/595,239 US20070140088A1 (en) | 2003-09-30 | 2004-09-29 | Evaluating apparatus and evaluating method |
JP2005514325A JPWO2005031743A1 (ja) | 2003-09-30 | 2004-09-29 | 評価装置および評価方法 |
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US (1) | US20070140088A1 (ja) |
JP (1) | JPWO2005031743A1 (ja) |
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EP2136369A2 (en) | 2008-06-18 | 2009-12-23 | Hitachi Ltd. | Optical information recording method, optical information reproduction method and optical disk device |
WO2010119722A1 (ja) * | 2009-04-14 | 2010-10-21 | 日立コンシューマエレクトロニクス株式会社 | 記録条件の調整方法,光ディスク装置,再生方法および情報の記録方法 |
WO2011089735A1 (ja) * | 2010-01-20 | 2011-07-28 | 日立コンシューマエレクトロニクス株式会社 | 記録条件の調整方法、光ディスク装置及び情報記録方法 |
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EP2136369A2 (en) | 2008-06-18 | 2009-12-23 | Hitachi Ltd. | Optical information recording method, optical information reproduction method and optical disk device |
US8208358B2 (en) | 2008-06-18 | 2012-06-26 | Hitachi, Ltd. | Optical information recording method, optical information reproduction method and optical disk device |
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WO2010119722A1 (ja) * | 2009-04-14 | 2010-10-21 | 日立コンシューマエレクトロニクス株式会社 | 記録条件の調整方法,光ディスク装置,再生方法および情報の記録方法 |
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US8085640B2 (en) | 2009-04-14 | 2011-12-27 | Hitachi Consumer Electronics Co., Ltd. | Adjusting method for recording condition and optical disc device |
US8264932B2 (en) | 2009-04-14 | 2012-09-11 | Hitachi Consumer Electronics Co., Ltd. | Adjusting method for recording condition and optical disc device |
WO2011089735A1 (ja) * | 2010-01-20 | 2011-07-28 | 日立コンシューマエレクトロニクス株式会社 | 記録条件の調整方法、光ディスク装置及び情報記録方法 |
JP2011150748A (ja) * | 2010-01-20 | 2011-08-04 | Hitachi Consumer Electronics Co Ltd | 記録条件の調整方法及び光ディスク装置 |
US8483028B2 (en) | 2010-01-20 | 2013-07-09 | Hitachi Consumer Electronics Co., Ltd. | Method for adjusting recording condition, optical disc device, and information recording method |
US8743671B2 (en) | 2010-01-20 | 2014-06-03 | Hitachi Consumer Electronics Co., Ltd. | Method for adjusting recording condition, optical disc device, and information recording method |
Also Published As
Publication number | Publication date |
---|---|
CN1886794A (zh) | 2006-12-27 |
US20070140088A1 (en) | 2007-06-21 |
JPWO2005031743A1 (ja) | 2006-12-07 |
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