JP2007149237A - Disk signal analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disk signal analyzer which is excellent in recording compensation and reproduction reliability and which has flexibility for coping with PRML processing. <P>SOLUTION: The analyzer is provided with an adaptive equalization part to which a digital value of an analog reproduction signal is input and which outputs adaptive equalization data equalized adaptively to ideal equalization data and an equalization error, a viterbi decoding part to which the adaptive equalization data is input and which decodes it using a viterbi algorithm, a data extraction part which searches the data decoded by the viterbi decoding part based on a prescribed extraction condition and which extracts the equalization error of data related to the retrieved data, a statistical operation part to which the extracted equalization error is input and which calculates and outputs a statistic value of the equalization error, and a display part which displays the statistic value which the statistic operation part outputs. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disk signal analyzing apparatus, and more particularly to a disk signal analyzing apparatus suitable for use in a write strategy analysis of a next generation high density optical disk that is decoded by PRML (Partial Response Maximum Likelihood) signal processing. .

  FIG. 11 shows the configuration of a conventional disk signal analyzing apparatus. A dotted line block represents a physical memory. In FIG. 11, the reproduction signal of the optical disc is input to the time measuring unit 11. The time measuring unit 11 includes a count counter, a T / V conversion circuit, a PLL circuit, etc., and binarizes the input reproduction signal and measures its code length (pulse width). This code length is stored in the code length memory 12. The extraction condition setting unit 13 sets an extraction condition for extracting a part of the reproduction signal. This setting is performed by key input from a key switch (not shown). The set extraction condition is stored in the extraction condition memory 14.

  The data extraction unit 15 is configured by software or the like, and the extraction conditions stored in the extraction condition memory 14 are input. The data extraction unit 15 searches the data stored in the code length memory 12, extracts data that matches the input extraction condition, and stores it in the extracted data memory 16.

  The statistical calculation unit 17 is configured by software or a DSP (Digital Signal Processor), calculates a statistical value of data stored in the extracted data memory 16, and stores it in the statistical value memory 18a. Further, the histogram of the extracted data is calculated and stored in the histogram memory 18b. The display unit 19 displays the data stored in the statistical value memory 18a and the histogram memory 18b on a CRT or a liquid crystal display.

  Next, the operation of the disk signal analyzing apparatus will be described with reference to the flowchart of FIG. In FIG. 12, time measurement is performed by the time measurement unit 11 in step (12-1). The time measuring unit 11 binarizes the input reproduction signal, measures the code length (pulse width), and stores the measurement result in the code length memory 12. FIG. 14A shows an example of a stored value of the code length memory 12, in which data of 110.25 nsec, 111.50 nsec... Is stored.

  FIG. 13 shows the relationship between the track of the optical disc and the binarized signal. FIG. 13A shows a track formed on the surface of the optical disk, and a blacked out portion is a track mark. By reading this track with an optical pickup, the reproduction signal shown in FIG. The time measuring unit 11 converts the reproduction signal into a binary signal shown in (C) by slicing the reproduction signal at a certain threshold level, and measures the code length of the binary signal.

  When the time measurement is completed, an extraction condition of, for example, “a space immediately after the 3T mark” is set in step (12-2). This extraction condition instructs to analyze the space (“0”) immediately after the 3T mark (code pattern “111”). Since DVD is T = 37 nsec, the length of the 3T mark is about 92.5 nsec to 129.5 nsec.

  Next, in the step (12-3), the code length memory 12 is searched based on the extraction condition, and data matching the extraction condition is extracted and stored in the extracted data memory 16. FIG. 14B shows an example of a stored value in the extracted data memory 16, in which data of a space immediately after 3T is stored. In this example, values of 111.50 nsec, 185.80 nsec... Are sequentially stored.

  Next, statistical calculation processing is performed in step (12-4). That is, the statistical calculation unit 17 classifies the extracted data stored in the extracted data memory 16 by code length, calculates an average value and a standard deviation for each code length, and stores them in the statistical value memory 18a. Further, the histogram of the extracted data is calculated and stored in the histogram memory 18b. FIG. 14C shows an example of stored values in the statistical value memory 18a. In this example, an average value and a standard deviation are stored for each code length. FIG. 14D is a graph of stored values in the histogram memory 18b. The code length distribution of the space from immediately after the 3T mark to 14T is stored. The vertical dotted line represents the ideal code length.

  And a result is displayed at a process (12-5). The display unit 19 reads the data stored in the statistical value memory 18a and the histogram memory 18b, and creates display data to be displayed in a list format as shown in FIG. 14C or a graph format as shown in FIG. . This display data is displayed on a CRT or a liquid crystal display. Finally, it is determined whether or not the analysis process is continued in the step (12-6). When continuing, the process returns to the step (12-2), and new spaces such as a space immediately before the 3T mark and a space immediately after the 14T mark are obtained. Set extraction conditions, and exit if you do not want to continue.

  FIG. 15 shows an example of intersymbol interference. (A) is a mark, and (B) is a binary signal generated by this mark. The mark size changes due to the thermal diffusion of the recording mark, and as a result, an edge shift occurs in the binarized signal.

  The write strategy of the optical disc apparatus can be determined using the histogram of FIG. In this figure, the histogram is shifted to the right with respect to the ideal code length (vertical dotted line) of 3T to 14T. For this reason, a write strategy such as increasing the laser irradiation time of the 2T mark or increasing the laser power at the edge is determined to reduce intersymbol interference. Further, another write strategy is examined according to the standard deviation value.

  In order to analyze an optical disk signal with high accuracy, time must be measured with high resolution. A technique for measuring time with high resolution and a technique for measuring jitter using a time measurement circuit are described in Patent Document 1 and Patent Document 2.

  An intersymbol interference analyzing apparatus that analyzes intersymbol interference, displays the result so that it can be intuitively understood, and can perform analysis efficiently is described in Patent Document 3. By using this analyzer, the write strategy can be analyzed.

  Patent Document 4 discloses a disk signal analyzer that can be applied to various PRML systems with a small circuit scale, can be applied to various PRML systems, and can appropriately perform histogram analysis even when errors are large. .

Patent Document 5 describes a PRML analyzer capable of obtaining a correlation with a PRML decoding system for signal evaluation of a next-generation optical disk.
Japanese Patent Laid-Open No. 7-27880 Japanese Patent Laid-Open No. 10-282165 JP 2001-126264 A JP 2003-203429 A JP 2005-182969 A

  However, such a disk signal analyzing apparatus has the following problems. In the next-generation high-density optical disc, the signal amplitude level of the reproduced waveform in the high range becomes small due to optical limitations. This will be described with reference to FIG. FIG. 16A shows an eye pattern of a reproduction signal of a conventional optical disc, and FIG. 16B shows an eye pattern of a reproduction signal of a next-generation high-density optical disc. The amplitude of the reproduction signal of the next-generation high-density optical disk has a small signal amplitude level of the reproduction waveform in the high band due to optical limitations. For this reason, there has been a problem that jitter when binarized and decoded increases.

  This will be described with reference to FIG. FIG. 17A shows a track of a next-generation high-density optical disc, FIG. 17B shows a reproduction signal thereof, and FIG. 17C shows a signal binarized at an appropriate threshold level. Since the reproduction signal has a lower quality than that of FIG. 13 and the amplitude is small, jitter increases when binarized and decoded. For this reason, when the write strategy analysis is performed by the conventional optical disk analysis apparatus shown in FIG. 11, optimum recording control cannot be performed.

  Therefore, next-generation high-density optical discs employ PRML decoding in order to improve reproduction reliability, thereby achieving both higher density and higher reliability. However, since it is not binary decoding, a write strategy analysis method has not been established, and there has been a problem that the reliability of a recordable or once-recorded disc cannot be improved.

  Therefore, an object of the present invention is to be used for write strategy analysis of next-generation high-density optical disks employing PRML decoding, and has excellent recording compensation, reproduction reliability, and flexible disk signal analysis suitable for PRML processing. To provide an apparatus.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
An AD converter for converting an analog reproduction signal into a digital value;
The digital value converted by the AD converter is input, and the adaptive equalized data adaptively equalized to the ideal equalized data and the equalization error that is the difference between the ideal equalized data and the adaptive equalized data are output. An adaptive equalization unit,
A Viterbi decoding unit that receives the adaptive equalization data and decodes it using a Viterbi algorithm;
A data extraction unit that retrieves data decoded by the Viterbi decoding unit based on a predetermined extraction condition, and extracts the equalization error of data related to the retrieved data;
A statistical calculation unit that inputs the extracted equalization error and calculates and outputs a statistical value of the equalization error;
A display unit for displaying the statistical value output by the statistical calculation unit;
Is provided. A disk signal analysis apparatus with high reliability and high degree of freedom in analysis can be obtained.

The invention according to claim 2 is the invention according to claim 1,
The data extraction unit is configured to extract equalization errors of all searched data. Equalization error data for the entire search position is obtained.

The invention according to claim 3 is the invention according to claim 1,
The data extraction unit extracts equalization errors of all searched data and outputs an average value thereof. Average equalization error data of the search position is obtained.

The invention according to claim 4 is the invention according to claim 1,
The data extraction unit is configured to extract equalization errors of data adjacent to all searched data. Equalization error data for a location adjacent to the search position is obtained.

The invention according to claim 5 is the invention according to claim 1,
The data extraction unit extracts equalization errors of all searched data, classifies them for each level, and outputs them. Equalization error data for each level of the entire search position is obtained.

The invention described in claim 6
An AD converter for converting an analog reproduction signal into a digital value;
An adaptive equalization unit that receives the digital value converted by the AD conversion unit and outputs adaptive equalization data adaptively equalized to ideal equalization data;
A Viterbi decoding unit that receives the adaptive equalization data, decodes it using a Viterbi algorithm, and outputs a difference metric;
A data extraction unit that retrieves data decoded by the Viterbi decoding unit based on a predetermined extraction condition, and extracts a difference metric of data related to the retrieved data;
A statistical calculation unit that inputs the extracted difference metric and calculates and outputs a statistical value of the difference metric;
A display unit for displaying the statistical value output by the statistical calculation unit;
Is provided. A disk signal analysis apparatus with high reliability and high degree of freedom in analysis can be obtained.

The invention according to claim 7 is the invention according to claim 6,
The data extraction unit is configured to extract a difference metric at a position determined by an extraction condition in the retrieved data. Difference metric data at an arbitrary position of the search data is obtained.

The invention according to claim 8 is the invention according to claim 6,
The data extraction unit is configured to extract a difference metric at a position adjacent to the retrieved data. Difference metric data of a position adjacent to the search position is obtained.

The invention according to claim 9 is the invention according to claim 1 or claim 8,
The statistical calculation unit outputs an average value and a standard deviation as statistical values. The state of the data of the extraction position can be immediately grasped.

The invention of claim 10 is the invention of claim 1 or claim 9,
The display unit creates and displays a histogram by code length of the data extracted by the data extraction unit. You can see the data distribution by code length.

The invention according to claim 11 is the invention according to claim 1 or claim 10,
The statistical calculation unit calculates a statistical value for each code length, and the display unit displays the statistical value in a list format. You can see the data distribution by code length.

The invention according to claim 12
An AD converter for converting an analog reproduction signal into a digital value;
An adaptive equalization unit that outputs adaptive equalization data obtained by adaptively equalizing ideal digital data with the digital value converted by the AD conversion unit;
A Viterbi decoding unit that receives the adaptive equalization data and decodes it using a Viterbi algorithm;
An error correction unit that receives data decoded by the Viterbi decoding unit, performs error correction processing on the data, and restores original data; and
An error rate that searches for data decoded by the Viterbi decoding unit based on a predetermined extraction condition, compares the data related to the searched data with the original data output by the error correction unit, and outputs an error rate A calculation unit;
A display unit for displaying the error rate calculated by the error rate calculation unit;
Is provided. A disk signal analysis apparatus with high reliability and high degree of freedom in analysis can be obtained.

The invention according to claim 13
An AD converter for converting an analog reproduction signal into a digital value;
An adaptive equalization unit that outputs adaptive equalization data obtained by adaptively equalizing ideal digital data with the digital value converted by the AD conversion unit;
A Viterbi decoding unit that receives the adaptive equalization data and decodes it using a Viterbi algorithm;
An external data capturing unit that reads original data corresponding to the data decoded by the Viterbi decoding unit;
An error rate that searches for data decoded by the Viterbi decoding unit based on a predetermined extraction condition, compares the data related to the searched data with the original data read by the external data capturing unit, and outputs an error rate A calculation unit;
A display unit for displaying the error rate calculated by the error rate calculation unit;
Is provided. A disk signal analysis apparatus with high reliability and high degree of freedom in analysis can be obtained.

The invention of claim 14 is the invention of claim 12 or claim 13,
The error rate calculation unit calculates an error rate using all data of the searched data. The error rate of the entire search position can be obtained.

As is apparent from the above description, the present invention has the following effects.
An adaptive equalization data is obtained from the disc playback signal, the adaptive equalization data is decoded by Viterbi decoding, the decoded data is searched based on a predetermined extraction condition, and an equalization error of a position related to the search position, The difference metric and error rate were selected and extracted and displayed. In addition, the statistical values of the equalization error and difference metric are calculated and displayed, and the histogram of the extracted data is created and displayed.

  Since an equalization error, a difference metric, and an error rate can be selected and handled as analysis parameters, there is an effect that a disk signal analysis apparatus having high reliability and high analysis freedom can be obtained. This is particularly effective when used for write strategy analysis of an optical disk drive using the PRML system adopted as a playback system for next-generation high-density optical disks.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a disk analyzing apparatus according to the present invention. In addition, the same code | symbol is attached | subjected to the same element as FIG. 11, and description is abbreviate | omitted. Further, as in FIG. 11, the dotted line block represents a physical memory.

  In FIG. 1, reference numeral 20 denotes a disk signal analyzing apparatus, which includes an extraction condition setting unit 13, an extraction condition memory 14, an AD conversion unit 21, an adaptive equalization unit 22, a Viterbi decoding unit 23, an equalization error memory 24, and a difference metric memory 25. The decoding data memory 26, the data extraction unit 27, the extraction data memory 28, the statistical calculation unit 29, the calculation data memory 31, and the display unit 32.

  The AD conversion unit 21 receives an optical disc reproduction signal. The AD converter 21 converts this reproduction signal into a digital value. The digital value converted by the AD conversion unit 21 is input to the adaptive equalization unit 22. The adaptive equalization unit 22 performs adaptive equalization processing on the digital value and outputs adaptive equalization data.

  The Viterbi decoding unit 23 receives adaptive equalization data output from the adaptive equalization unit 22. The Viterbi decoding unit 23 decodes the adaptive equalized data into a binary signal by the Viterbi algorithm and outputs the binary signal. The decoded binary signal is fed back to the adaptive equalization unit 22.

  The equalization error memory 24 stores an error of adaptive equalization data. This error is calculated while the adaptive equalization unit 22 performs the adaptive process. The difference metric memory 25 stores a difference metric (also called SAM) calculated by the Viterbi decoding unit 23 in the decoding process. The difference metric is obtained by calculating the difference between the next path metric and the adopted path metric for each bit. Since Viterbi decoding and difference metric (SAM) are described in Patent Document 4, the details thereof are omitted.

  The decoded data memory 26 stores a binary signal output from the Viterbi decoding unit 23. The extraction condition is set by the extraction condition setting unit 13 and stored in the extraction condition setting memory 14.

  The data extraction unit 27 searches the decoded data memory 26 for data that matches the extraction conditions stored in the extraction condition memory 14, and extracts the corresponding data from the equalization error memory 24, the difference metric memory 25, and the decoded data memory 26. To do. The extracted data is stored in the extracted data memory 28.

  The statistical calculation unit 29 performs predetermined statistical calculation processing on the data stored in the extracted data memory 28. This statistical calculation result is stored in the calculation data memory 31. The display unit 32 creates display data converted into a format that allows easy viewing of the data stored in the calculation data memory 31 and the extracted data memory 28. This display data is displayed on a CRT or liquid crystal display (not shown).

  Next, the operation of this embodiment will be described based on the flowchart of FIG. In FIG. 2, in step (2-1), the AD conversion unit 21 converts the reproduction signal into a digital value and outputs the digital value to the adaptive equalization unit 22. Next, in step (2-2), the adaptive equalization unit 22 performs adaptive equalization processing on the input digital value and outputs adaptive equalization data. That is, equalization processing is performed using an LMS (Least Mean Square) algorithm or the like so as to approximate the optical transfer response characteristic of the optical pickup.

  Generally, the characteristics of the optical disc are close to the response characteristics called PR (121) and PR (1221), but in this embodiment, it is assumed that the optical disk has the response characteristics of PR (1221). The adaptive equalization unit 22 operates adaptively so that the output waveform approaches the 7-value ideal equalized data in PR (1221), and outputs adaptive equalized data. At this time, an equalization error which is an error between the ideal equalization data and the adaptive equalization data (“ideal equalization data” − “adaptive equalization data”) is calculated, and this equalization error is stored in the equalization error memory 24. To do.

  Next, a Viterbi decoding process is performed in step (2-3). The Viterbi decoding unit 23 performs binary decoding from the adaptive equalized data using the Viterbi algorithm, and stores the difference metric data calculated in the decoding process in the difference metric memory 25 and the decoded data in the decoded data memory 26.

  Next, data extraction processing is performed in step (2-4). First, an extraction condition is set by the extraction condition setting unit 13 and stored in the extraction condition memory 14. The data extraction unit 27 searches the decoded data memory 26 for data that matches the extraction condition stored in the extraction condition memory 14, and extracts the corresponding data from the equalization error memory 24 and the difference metric memory 25.

  Next, statistical calculation processing is performed in step (2-5). The statistical calculation unit 29 reads the data stored in the extracted data memory 28, calculates the average value and the standard deviation, and stores them in the calculation data memory 31 in the format as shown in FIG. Next, the data stored in the calculation data memory 31 or the like in the step (2-6) is displayed. Then, in step (2-7), it is determined whether or not to continue the analysis. If so, the process returns to step (2-4) to set a new extraction condition.

  FIG. 3 is a diagram showing the adaptive equalized output waveform, decoded data, ideal equalized data, adaptive equalized data, equalization error, and difference metric for each clock. (A) is decoded data stored in the decoded data memory 26, (B) is ideal equalization data, (C) is adaptive equalization data calculated by the adaptive equalization unit 22, and (D) is ideal equalization data. And (E) is a difference metric calculated by the Viterbi decoding unit 23.

  The upper graph is a graph of ideal equalization data and adaptive equalization data, with white circles (◯) representing ideal equalization data and black circles (●) representing adaptive equalization data. The adaptive equivalent unit 22 operates adaptively so that the adaptive equalization data (●) approaches the ideal equalization data (◯). Levels L0 to L6 correspond to 7-value ideal equalization data 0 to 6, respectively. In addition, ∞ in the difference metric column of (E) comes from the 1-7 modulation code rule adopted in the next generation optical disc, and means that the path metric at the time of Viterbi decoding exists only on one side. .

  When the extraction condition is set to “4T mark total equalization error”, the data extraction unit 27 searches 4T (“1111”) from the decoded data and stores all the 4T equalization errors in the extraction data memory 28. In FIG. 3, 41 portions (data: 0.28, 0.26, 0.11, 0.20) are extracted. The data extraction unit 27 searches all data stored in the decoded data memory 26, extracts all equalization errors in the 4T portion, and stores them in the extracted data memory 28. An example of the extraction result is shown in FIG.

  When the extraction condition is set to “equalization error average of 4T mark”, the data extraction unit 27 retrieves 4T (“1111”) from the decoded data, and stores the average value of all retrieved equalization errors in the extracted data memory 28. Store. In FIG. 3, an average value 0.21 of 41 pieces of data (0.28, 0.26, 0.11, 0.20) is stored in the extracted data memory 28. The data extraction unit 27 searches all the data stored in the decoded data memory 26 and stores the average value of the equalization error of the 4T portion in the extracted data memory 28. FIG. 4B shows an example of the extraction result.

  When the extraction condition is set to “equalization error immediately after the 4T mark”, the data extraction unit 27 searches the decoded data for the 4T mark (“1111”) and extracts the data 0.08 immediately after that (42 in FIG. 3). And stored in the extracted data memory 28. An example of the extraction result is shown in FIG. In addition, not only immediately after but the adjacent position may be sufficient.

  When the extraction condition is set as “equalization error for each level of 3T space continuous after the 4T mark”, the data extraction unit 27 retrieves “1111000” from the decoded data memory 26, and the equalization error (43 in FIG. 3). ) Are classified by level and stored in the extracted data memory 28. An example of the extraction result is shown in FIG.

  When the extraction condition is set to “difference metric of rising edge of 2T mark after 2T space”, the data extraction unit 27 retrieves “0011” from the decoded data memory 26 and determines the difference metric (1st “1”) of the rising edge (first “1”). 44 of FIG. 3, data: 11.04, 9.79) are extracted and stored in the extracted data memory 28. An example of the extraction result is shown in FIG. In addition to the rising edge, an arbitrary position of data that matches the search condition may be designated. Various search conditions and detailed conditions can be set in addition to those described above.

  Next, operations of the statistical calculation unit 29 and the display unit 32 will be described. The statistical calculation unit 29 calculates the average value and standard deviation of the data stored in the extracted data memory 28 and stores it in the calculation data memory 31. FIG. 5 shows an example of statistical processing. FIG. 5A is an example of statistical processing whose detailed condition is “total equalization error”. An average value ave and a standard deviation σ are calculated. FIG. 5B shows an example of statistical processing whose detailed condition is “equalization error by level”. The average value ave and the standard deviation σ are calculated for each level. The display unit 32 displays these values in a text format.

  FIG. 6A shows an example of values stored in the calculation data memory 31 and a display displayed on the display unit 32 when the detailed condition is “total equalization error of 2T to 9T”. The lower row shows the average value ave and standard deviation σ for each code length (T), and the upper row shows a histogram for each code length. The dotted line in the histogram indicates a point with zero error.

  The data extraction unit 27 searches for data matching the extraction condition for each code length and stores it in the extracted data memory 28. The statistical calculation unit 29 reads the extracted data memory 28 and calculates an average value and a standard deviation for each code length as shown in the lower part of FIG. The display unit 32 displays these average values and standard deviations, and creates and displays a histogram for each code length with reference to the extracted data memory 28. Based on the shape of the histogram, the shift amount from the ideal value, the dispersion amount, etc., it is possible to study the optimum write strategy corresponding to the code length.

  FIG. 6B shows the result when “4T mark 3T space equalization error by level” is set as the extraction condition, and the average value, standard deviation and histogram are calculated and displayed for each level. The right side is the calculated value of the average value ave and standard deviation σ, and the left side is the histogram. A blacked-out 51 is a histogram extracted under the condition of a 4T mark 3T space, a solid line 52 is a histogram of all data, and a dotted line represents a zero error point.

  FIG. 6C shows the result when “2T space 2T mark rise difference metric” is used as the extraction condition, and the horizontal axis is the difference metric (SAM). A black-out portion 53 is a histogram of data extracted under the condition of “2T space 2T mark”, and a solid line 54 is a histogram of all data in which the ideal value of the difference metric is 10. Since the histogram 53 of the extracted data is shifted to the zero side with respect to the whole histogram 54, the write strategy may be optimized so that the difference metric approaches 10 ideal. ave is the average value of the difference metric, and σ is the standard deviation.

  In FIG. 6C, the average value, standard deviation, and histogram are one, but the extracted data may be classified by code length, and the average value, standard deviation, and histogram may be obtained for each code length.

  In the embodiment of FIG. 1, both the equalization error memory 24 and the difference metric memory 25 are provided, and both the equalization error and the difference metric are used. However, as can be seen from FIGS. 6B and 6C. Thus, the write strategy can be performed using either the equalization error or the difference metric. Accordingly, either the equalization error memory 24 or the difference metric memory 25 may be provided.

  FIG. 7 shows another embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same element as FIG. 1, and description is abbreviate | omitted. In FIG. 7, reference numeral 60 denotes a disk signal analyzing apparatus, which includes an extraction condition setting unit 13, an extraction condition memory 14, an AD conversion unit 21, an adaptive equalization unit 22, a Viterbi decoding unit 23, a decoded data memory 26, an error correction unit 61, An original data memory 62, an external data capturing unit 63, an error rate calculating unit 64, an error rate memory 65, and a display unit 32 are included.

  The error correction unit 61 receives the output of the Viterbi decoding unit 23. The error correction unit 61 performs error correction from the input data using a Reed-Solomon product code algorithm or the like, and generates original data serving as a reference for comparison with decoded data. This original data is stored in the original data memory 62.

  The external data capturing unit 63 captures original data serving as a reference for comparison with the decoded data using a communication unit such as a file or Ethernet (registered trademark), and stores the original data in the original data memory 62. The file is stored in an externally connected hard disk, optical disk, or USB memory.

  An extraction condition stored in the extraction condition memory 14 is input to the error rate calculation unit 64. The error rate calculation unit 64 compares the data that matches the extraction condition among the data stored in the decoded data memory 26 and the original data memory 62, and calculates an error rate that is a ratio that does not match. This error rate is stored in the error rate memory 65. The display unit 32 displays the contents of the error rate memory 65.

  The operation of this embodiment will be described with reference to the flowchart of FIG. In FIG. 8, the reproduction signal is converted into a digital value in step (8-1), and adaptive equalization processing is performed using the adaptive equalization unit 22 in step (8-2). In step (8-3), decoding is performed using the Viterbi decoding unit 23, and the decoded data is stored in the decoded data memory 26 and output to the error correction unit 61. The steps so far are almost the same as those in FIG.

  Next, error correction processing is performed in step (8-4). The error correction unit 61 performs error correction from the data input from the Viterbi decoding unit 23 using a Reed-Solomon product code algorithm or the like, generates original data, and stores the original data in the original data memory 62.

  Next, an error rate is calculated in step (8-5). Before calculating the error rate, the extraction condition setting unit 13 sets the extraction condition and stores it in the extraction condition memory 14. The error rate calculation unit 64 searches the decoded data memory 26 for data that matches the extraction condition stored in the extraction condition memory 14, and compares this data with the data stored in the original data memory 62 to calculate the error rate. And stored in the error rate memory 65. FIG. 10A shows an example of storing the error rate.

  Next, the error rate is displayed in step (8-6). The display unit 32 displays the error rate in a format such as that shown in FIG. Finally, it is determined whether or not to continue the analysis in step (8-7). When continuing, the process returns to step (8-5), and when not continuing, the process ends.

  FIG. 9 shows the decoded data and original data of this embodiment every clock. In FIG. 9, (A) is the decoded data output from the Viterbi decoding unit 23, (B) is the original data, black circles (●) are the adaptive equalization data output from the adaptive equalization unit 22, and white circles (○) Represents ideal equalization data.

  If the extraction condition is set to “error rate of 4T space continuous to 2T mark”, 71 is the extraction range. Since the number of data in this range is 6 and the number of error data is 1, the error rate is 17%. FIG. 9 shows a part of the data. Actually, there are other areas satisfying the “4T space continuous with the 2T mark”, so the error rate has a different value.

  In FIG. 7, both the configuration in which the error correction unit 61 reconstructs the original data and the configuration in which the original data is fetched from the external data fetching unit 63 are provided. .

In these embodiments, information for performing a write strategy is provided by the following four methods.
(1) Use statistical value / histogram of equalization error.
(2) Use statistic / histogram of difference metric.
(3) Using the error rate obtained by comparing the original data and the decoded data, the original data is created from the decoded data by error correction.
(4) The original data is input from the outside using an error rate obtained by comparing the original data and the decoded data.
These techniques may be used alone or in combination.

It is a block diagram which shows one Example of this invention. It is a flowchart which shows operation | movement of one Example of this invention. It is a characteristic view which shows an example of data. It is the figure which showed the example of the value stored in each memory. It is the figure which showed the example of the value stored in each memory. It is the figure which illustrated the display of a statistics value and a histogram. It is a block diagram which shows the other Example of this invention. It is a flowchart which shows operation | movement of the other Example of this invention. It is a characteristic view which shows an example of data. It is the figure which showed the example of storage of an error rate, and the example of a display. It is a block diagram of the conventional disc signal analysis apparatus. It is a flowchart which shows operation | movement of the conventional disc signal analysis apparatus. FIG. 4 is a waveform diagram showing the relationship between a track of an optical disc and a reproduction signal. It is the figure which showed the example of storage of each memory. It is a figure explaining that edge shift occurs by intersymbol interference. It is an eye pattern of a reproduction signal of an optical disc. It is a figure explaining that a jitter increases.

Explanation of symbols

DESCRIPTION OF SYMBOLS 13 Extraction condition setting part 14 Extraction condition memory 20, 60 Disk signal analyzer 21 AD conversion part 22 Adaptive equalization part 23 Viterbi decoding part 24 Equalization error memory 25 Difference metric memory 26 Decoded data memory 27 Data extraction part 28 Extracted data memory 29 Statistical Operation Unit 31 Operation Data Memory 32 Display Unit 41 to 44 Extracted Data 51 to 54 Histogram 61 Error Correction Unit 62 Original Data Memory 63 External Data Capture Unit 64 Error Rate Calculation Unit

Claims (14)

An AD converter for converting an analog reproduction signal into a digital value;
The digital value converted by the AD converter is input, and the adaptive equalized data adaptively equalized to the ideal equalized data and the equalization error that is the difference between the ideal equalized data and the adaptive equalized data are output. An adaptive equalization unit,
A Viterbi decoding unit that receives the adaptive equalization data and decodes it using a Viterbi algorithm;
A data extraction unit that retrieves data decoded by the Viterbi decoding unit based on a predetermined extraction condition, and extracts the equalization error of data related to the retrieved data;
A statistical calculation unit that inputs the extracted equalization error and calculates and outputs a statistical value of the equalization error;
A display unit for displaying the statistical value output by the statistical calculation unit;
A disc signal analyzing apparatus comprising:   2. The disk signal analyzing apparatus according to claim 1, wherein the data extracting unit extracts equalization errors of all searched data.   2. The disk signal analyzing apparatus according to claim 1, wherein the data extracting unit extracts equalization errors of all searched data and outputs an average value thereof.   2. The disk signal analyzing apparatus according to claim 1, wherein the data extracting unit extracts an equalization error of data adjacent to all searched data.   2. The disk signal analyzing apparatus according to claim 1, wherein the data extracting unit extracts equalization errors of all searched data, classifies them for each level, and outputs them. An AD converter for converting an analog reproduction signal into a digital value;
An adaptive equalization unit that receives the digital value converted by the AD conversion unit and outputs adaptive equalization data adaptively equalized to ideal equalization data;
A Viterbi decoding unit that receives the adaptive equalization data, decodes it using a Viterbi algorithm, and outputs a difference metric;
A data extraction unit that retrieves data decoded by the Viterbi decoding unit based on a predetermined extraction condition, and extracts a difference metric of data related to the retrieved data;
A statistical calculation unit that inputs the extracted difference metric and calculates and outputs a statistical value of the difference metric;
A display unit for displaying the statistical value output by the statistical calculation unit;
A disc signal analyzing apparatus comprising:   7. The disk signal analyzing apparatus according to claim 6, wherein the data extraction unit extracts a difference metric at a position determined by an extraction condition in the retrieved data.   7. The disk signal analyzing apparatus according to claim 6, wherein the data extracting unit extracts a difference metric at a position adjacent to the searched data.   9. The disk signal analyzing apparatus according to claim 1, wherein the statistical values calculated and output by the statistical calculation unit are an average value and a standard deviation.   10. The disk signal analyzing apparatus according to claim 1, wherein the display unit creates and displays a histogram by code length of the data extracted by the data extraction unit.   11. The disk signal analysis according to claim 1, wherein the statistical calculation unit calculates a statistical value for each code length, and the display unit displays the statistical value in a list format. apparatus. An AD converter for converting an analog reproduction signal into a digital value;
An adaptive equalization unit that outputs adaptive equalization data obtained by adaptively equalizing ideal digital data with the digital value converted by the AD conversion unit;
A Viterbi decoding unit that receives the adaptive equalization data and decodes it using a Viterbi algorithm;
An error correction unit that receives data decoded by the Viterbi decoding unit, performs error correction processing on the data, and restores original data; and
An error rate that searches for data decoded by the Viterbi decoding unit based on a predetermined extraction condition, compares the data related to the searched data with the original data output by the error correction unit, and outputs an error rate A calculation unit;
A display unit for displaying the error rate calculated by the error rate calculation unit;
A disc signal analyzing apparatus comprising: An AD converter for converting an analog reproduction signal into a digital value;
An adaptive equalization unit that outputs adaptive equalization data obtained by adaptively equalizing ideal digital data with the digital value converted by the AD conversion unit;
A Viterbi decoding unit that receives the adaptive equalization data and decodes it using a Viterbi algorithm;
An external data capturing unit that reads original data corresponding to the data decoded by the Viterbi decoding unit;
An error rate that searches for data decoded by the Viterbi decoding unit based on a predetermined extraction condition, compares the data related to the searched data with the original data read by the external data capturing unit, and outputs an error rate A calculation unit;
A display unit for displaying the error rate calculated by the error rate calculation unit;
A disc signal analyzing apparatus comprising: 14. The disk signal analyzing apparatus according to claim 12, wherein the error rate calculating unit calculates an error rate using all data of the searched data.

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