JP2002251824A - Method of sampling many-valued recording data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit sampling of many-valued recording data of regenerative signals having a high recording density and to perform exact sampling capable of dealing with momentary changes of many-valued data periods. SOLUTION: When the absolute value of the difference between two pieces of the data of a prescribed time interval below the period of the many-valued data detected by a sampling timing detection section 6 is above a prescribed value and the maximal value and minimal value on the outer side of two pieces of the data exist within the prescribed time interval, the time interval of the maximal value and minimal value is determined as the many-valued data period and the maximal value and/or the minimal value thereof is detected as a reference position of the sampling time and a data extraction section 4 performs the sampling of the data obtained by analog-to-digital conversion at the many- valued data periods from the reference position detected by the sampling timing detection section 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of sampling multi-valued recording data useful for reproducing multi-valued data recorded on a recording medium such as an optical disc in an information recording / reproducing apparatus such as an optical disc apparatus. About.

[0002]

2. Description of the Related Art Conventionally, in quantizing a multi-valued information reproduction signal from a recording medium, a technique of changing a reference level for quantization by using a reproduction signal corresponding to a level synchronization code (for example, Japanese Patent Laid-Open No. 5-266588). There has also been proposed a method of sampling multi-valued recording data in which a pattern that indicates the cycle of multi-value data is added to a synchronization signal, and at the time of reproduction, the multi-value data is sampled at a cycle detected from the pattern.

[0003]

However, in the conventional multi-valued recording data sampling method, since the sampling timing of the multi-valued data is determined by a method of detecting a change point of the reproduction signal, the reproduction signal waveform has a staircase. When the recording density is further increased, the reproduction signal waveform becomes a gentle sine wave shape, and it becomes difficult to detect a change point (see FIG. 9). As a result, there is a problem that it is not possible to determine an accurate sampling timing of the multi-value data. Further, if the sampling timing is determined only from the pattern of the synchronization signal, it is not possible to cope with the instantaneous change of the multi-value data cycle due to uneven rotation of the disk or the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to sample multi-valued recording data of a reproduction signal having a high recording density, and to cope with an ever-changing multi-valued data period. It is an object of the present invention to perform as accurate sampling as possible.

[0005]

According to the present invention, in order to achieve the above object, a reproduction signal from a recording medium on which multi-valued data is recorded is converted from analog to digital based on a clock having a predetermined period, and the analog / digital conversion is performed. In the method of sampling multi-valued recording data obtained by performing digital conversion, the absolute value of the difference between two data at a predetermined time interval equal to or less than the cycle of the multi-valued data is equal to or more than a predetermined value, and When the maximum value and the minimum value outside the data exist within a predetermined time interval, the time interval between the maximum value and the minimum value is set as a multi-value data cycle, and the maximum value and / or the minimum value are set as a reference position of the sampling timing. And performs sampling of the data obtained by performing the above-described analog-to-digital conversion from the detected reference position in a multi-value data cycle.

A method of sampling multi-valued recording data obtained by performing analog-to-digital conversion on a reproduction signal from a recording medium on which multi-valued data is recorded based on a clock having a predetermined period, and performing the analog-to-digital conversion. Wherein the absolute value of the difference between two data at predetermined time intervals equal to or less than the cycle of the multi-valued data is equal to or greater than a predetermined value, and the time interval between the maximum value and the minimum value outside the two data values is multi-valued When the data coincides with one cycle of the data, the maximum value and / or the minimum value are detected as a reference position of the sampling timing, and the analog-digital conversion is performed at the multi-value data period from the detected reference position. Data sampling may be performed.

Further, in the above-described method of sampling multi-valued recording data, if the maximum value and the minimum value outside the two data do not exist within a predetermined time interval,
It is preferable to perform sampling of data obtained by performing analog-to-digital conversion in a multi-value data cycle from the reference position detected in the previous sampling timing detection operation.

In the above-described multi-value recording data sampling method, if the maximum value and the minimum value outside the two data do not coincide with one cycle of the multi-value data, the previous sampling timing It is preferable to perform sampling of data obtained by analog-to-digital conversion in a multi-value data cycle from the reference position detected by the detection operation.

Further, in the above-described method of sampling multi-valued recording data, the first sampling timing obtained by the sampling timing detecting operation and the detection of the sampling timing after detecting one cycle of the multi-valued data. It is preferable to compare the second sampling timing detected by the operation and, if the difference is equal to or greater than a predetermined value, to perform subsequent data sampling at the first sampling timing.

In the above-described method of sampling multi-valued recording data, the first sampling timing obtained by the sampling timing detection operation and the detection of the sampling timing after one cycle of the multi-valued data are detected. It is preferable to compare the second sampling timing detected by the operation and, if the difference is equal to or less than a predetermined value, perform subsequent data sampling at the second sampling timing.

Further, in the above-described method of sampling multi-valued recording data, the magnitude of the absolute value of the difference between two data at a predetermined time interval of one cycle or less of the multi-valued data is set to be greater than or equal to the multi-level level difference. Good to do.

Further, in the above-described method of sampling multi-valued recording data, the multi-valued recording data may be
When the value of n is a positive integer as described above, if the magnitude of the absolute value of the difference between two data at a predetermined time interval equal to or less than the cycle of the multi-valued data is equal to or more than the (n-2) value level difference Good.

[0013]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of an optical disc apparatus that executes a method of sampling multi-valued recording data according to an embodiment of the present invention. FIG. 2 is a diagram showing a reproduction signal waveform of multi-valued recording data according to one embodiment of the present invention. 3 and 5 to 8
FIG. 3 is a reproduction signal waveform chart for explaining a method of sampling multi-valued recording data according to the embodiment. FIG.
FIG. 3 is a signal waveform diagram used for describing the operation of the sampling timing detection unit in FIG. 1.

As shown in FIG. 2, a quaternary (level 0 to 3) signal is used as a reproduced signal of the multi-valued recording data in this embodiment, and the reproduced signal is analog-digital (A / A / D). D) The signal after conversion and further waveform equalization processing. In the sampling method of the multi-valued recording data of this embodiment, the period of the multi-valued data is detected from the signal to sample the multi-valued recording data.

As shown in FIG. 1, the A / D converter 1 A / D converts a reproduced signal with a clock having a fixed period shorter than the multi-value data period from the oscillator 5, and a waveform equalizer 2 performs waveform conversion. After the conversion (see FIG. 3), the data is stored in the memory 3. Sampling timing detector 6
Is determined by detecting a multi-value data cycle and a sampling reference point from the data on the memory 3. After that, the data extracting unit 4 extracts and outputs multi-value data in the memory 3 based on the sampling timing determined by the sampling timing detecting unit 6.

Next, the operation of the sampling timing detecting section will be described. Since the time interval between point A (multi-level 3) and point B (multi-level 0) in the signal in FIG. 2 indicates the cycle of the multi-value data, points A and B are detected by the following method. First, a difference “d2” between two data points C and D at a time interval “t1” shorter than a reference multilevel data cycle is sequentially calculated, and its absolute value is set to a predetermined value (for example, the difference between adjacent multilevel levels). If it is equal to or more than twice (d1), it is regarded as a change from level 3 to 0 or from 0 to 3 of the multilevel data.

Next, the maximum value and the minimum value of the signal outside the points C and D are obtained. If d2 is positive, A / D after point D
The difference between adjacent data of the converted data is sequentially calculated, and the data before the sign of the difference is inverted becomes the maximum value. On the other hand, as for the minimum value, the difference between the data adjacent to the A / D conversion data before the point C is sequentially calculated, and the data before the sign of the difference is inverted becomes the minimum value. When the maximum value and the minimum value obtained by the above-described processing are within the time interval “t2” longer than the reference multi-value data cycle including t1 at the center, the maximum value and the minimum value are respectively set to the point A. Let it be point B (process according to claim 1 of the present invention).

The reason that the maximum value and the minimum value are within the time interval "t2" is as follows. For example, as shown in FIG. 4, the maximum value and the minimum value cannot be obtained at the changing point when the maximum value and the minimum value of the multilevel level are continuous as shown in FIG. In such a case, the data cycle from the previous reference position obtained by the same detecting means is used without calculating the data cycle (the process according to claim 3 of the present invention).

It is determined whether the time interval between the maximum value and the minimum value matches the reference multi-valued data period, and if they match, the maximum value and the minimum value are set to point A and point B, respectively ( Processing according to claim 2 of the present invention). Further, when the time interval between the maximum value and the minimum value does not coincide with the reference multi-value data cycle, the data cycle from the previous reference position obtained by the same detection means is used (claim 4 of the present invention).
Related processing).

Further, the time interval between the point A and the point B obtained in the above processing is set as a multi-value data cycle, and the sampling timing based on the point A or the point B is determined. 4). At this time, the currently determined sampling timing is compared with the previous sampling timing, and only when the difference is equal to or smaller than a predetermined value (see FIGS. 5 to 7), the currently determined sampling timing may be used. (Processing according to claim 6 of the present invention). On the other hand, when the difference is equal to or greater than the predetermined value (see FIG. 6), the sampling timing determined by the previous detection operation may be used as it is (the processing according to claim 5 of the present invention).

If d2 is set small, the noise component may be recognized as a reproduced signal, and the sampling interval and sampling timing may be detected incorrectly (see FIG. 8). Therefore, it is preferable to set d2 to be equal to or larger than the multilevel level difference (processing according to claim 7 of the present invention).

Further, as described above, in the case of a four-valued [n-value] signal (n is a positive integer of 2 or more), the magnitude of the absolute value of d2 is determined by (multi-value level 4—multi-value level 2). [N-2] (difference 2) or more. Then, it is determined that the maximum value and the minimum value obtained by the subsequent operations indicate the maximum value (multi-value level 3) and the minimum value (multi-value level 0) of the multi-value level (see FIG. 2). Let these be points A and B, respectively (processing according to claim 8 of the present invention). Since the level difference is as large as possible in this way, it is possible to detect more accurate sampling timing for noise. In the case of an eight-level signal, the magnitude of d2 may be equal to or more than six multilevel level differences.

As described above, according to the multi-valued recording data sampling method according to the first embodiment of the present invention, the sampling timing can be determined again even when the sampling timing of the multi-valued data in the reproduction signal is shifted. Therefore, it is possible to accurately sample multi-value data even for a reproduction signal having a high recording density, and to cope with a momentary change in a multi-value data cycle.

[0024] Further, claim 2 of the present invention of this embodiment.
In the multi-valued recording data sampling method according to the above, the sampling timing can be determined again even when the sampling timing of the multi-valued data in the reproduced signal is shifted, so that the multi-valued data can be accurately reproduced even for the reproduced signal of high recording density. Sampling can be performed, and it is possible to cope with an ever-changing multi-value data cycle.

Further, in the method of sampling multi-valued recording data according to claim 3 of the present invention, the reproduced signal has a maximum value and a minimum value within a predetermined time interval as shown in FIG. If not, by using the sampling timing obtained in the previous processing, multi-valued data can be sampled without interrupting the processing, and it is possible to cope with the ever-changing multi-valued data cycle.

Further, in the present embodiment, claim 4 of the present invention is provided.
In the multi-valued recording data sampling method according to the above, if the time interval between the maximum value and the minimum value obtained by the sampling timing detection operation does not match the reference multi-value data cycle, the sampling timing obtained in the previous process is used. By using this, multi-valued data can be sampled without interrupting the processing, and it is possible to cope with the ever-changing multi-valued data cycle.

Further, in the method for sampling multi-valued recording data according to claim 5 of the present invention, the currently determined sampling timing is compared with the previous sampling timing, and when the difference is greater than a predetermined value, Since the previously determined sampling timing is used, disturbance of the sampling timing due to a signal abnormality due to a partial defect of the optical disk or the like can be prevented, and accurate multi-valued data can be sampled without interrupting the operation. (See FIG. 6).

Further, according to a sixth aspect of the present invention,
In the multi-valued recording data sampling method according to the above, the currently determined sampling timing is compared with the previous sampling timing, and only when the difference is equal to or less than a predetermined value, the currently determined sampling timing is used. Disturbance in sampling timing due to a signal abnormality due to a partial defect of the optical disk or the like can be prevented, and accurate sampling of multi-value data can be performed (see FIGS. 5 to 7).

Further, in the multi-valued recording data sampling method according to claim 7 of the present invention, if d2 is set too small, a noise component is recognized as a reproduced signal, and the sampling interval and sampling timing are reduced. Since d2 may be erroneously detected (see FIG. 8), by setting d2 to be equal to or larger than the multilevel difference, accurate multilevel data can be obtained without being affected by small noise components smaller than the multilevel difference. Data sampling is possible.

Further, in the sampling method of multi-valued recording data according to claim 8 of the present invention, the maximum change point of the multi-valued data in the reproduction signal is detected, and the sampling timing of the multi-valued data is determined. Because it is determined, it is hard to be affected by noise, and it is possible to accurately sample multi-valued data even for playback signals with high recording density, and to respond to the ever-changing multi-valued data cycle. it can.

[0031]

As described above, according to the multi-valued recording data sampling method of the present invention, multi-valued recording data of a reproduced signal having a high recording density can be sampled, and the multi-valued data period is sometimes changed. Accurate sampling capable of responding to ever-changing changes can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part of an optical disc device that executes a method of sampling multi-valued recording data according to an embodiment of the present invention.

FIG. 2 is a diagram showing a reproduction signal waveform of multi-level recording data according to an embodiment of the present invention.

FIG. 3 is a reproduction signal waveform diagram for describing a method of sampling multi-valued recording data according to the embodiment of the present invention.

FIG. 4 is a signal waveform diagram for describing an operation of the sampling timing detection unit in FIG. 1;

FIG. 5 is a reproduction signal waveform diagram for explaining a method of sampling multi-valued recording data according to the embodiment of the present invention, similarly to FIG. 3;

FIG. 6 is a reproduction signal waveform diagram for explaining a method of sampling multi-valued recording data according to the embodiment of the present invention, similarly to FIGS. 3 and 5;

FIG. 7 is a reproduction signal waveform diagram used for describing a method of sampling multi-valued recording data according to the embodiment of the present invention, similarly to FIGS. 3, 5 and 6;

FIG. 8 is a reproduction signal waveform diagram for explaining the method of sampling multi-valued recording data according to the embodiment of the present invention, similarly to FIGS. 3, 5 to 7;

FIG. 9 is a signal waveform diagram for explaining a conventional method of sampling multi-valued recording data.

[Explanation of symbols]

 1: A / D converter 2: Waveform equalizer 3: Memory 4: Data extractor 5: Oscillator 6: Sampling timing detector

Claims (8)

[Claims] An analog-to-digital conversion of a reproduction signal from a recording medium on which multi-valued data is recorded based on a clock having a predetermined period, and a method of sampling multi-valued recording data obtained by performing the analog-to-digital conversion. The absolute value of the difference between two data at a predetermined time interval equal to or less than the cycle of the multi-valued data is equal to or more than a predetermined value, and the maximum value and the minimum value outside the two data are within a predetermined time interval. If present, the time interval between the maximum value and the minimum value is set as a multi-value data cycle, the maximum value and / or the minimum value is detected as a reference position of the sampling timing, and the multi-value data cycle is determined from the detected reference position. Sampling the data obtained by the analog-to-digital conversion in step (a). 2. A method of sampling multi-valued recording data obtained by performing analog-to-digital conversion on a reproduction signal from a recording medium on which multi-valued data is recorded based on a clock having a predetermined period, and performing the analog-to-digital conversion. The absolute value of the difference between two data at a predetermined time interval equal to or less than the cycle of the multi-valued data is equal to or greater than a predetermined value, and the time interval between the maximum value and the minimum value outside the two data values is multi-valued. When the data coincides with one cycle of the data, the local maximum value and / or the local minimum value are detected as a reference position of the sampling timing, and the analog-to-digital conversion is performed at the multi-value data period from the detected reference position. A method of sampling multi-valued recording data, characterized by sampling data. 3. The sampling method according to claim 1, wherein if the maximum value and the minimum value outside the two data do not exist within a predetermined time interval, the previous sampling timing is detected. A method of sampling multi-valued recording data, wherein data obtained by performing analog-to-digital conversion in a multi-value data cycle from a reference position detected by an operation is sampled. 4. The multi-level recording data sampling method according to claim 2, wherein if the maximum value and the minimum value outside the two data do not coincide with one cycle of the multi-value data, the previous sampling timing Sampling the data obtained by analog-to-digital conversion in a multi-value data cycle from a reference position detected by the detection operation of (1). 5. The multi-valued recording data sampling method according to claim 1, wherein a first sampling timing obtained by the sampling timing detecting operation and one cycle of the multi-valued data. Comparing the second sampling timing detected by the detection operation of the sampling timing after the detection, and if the difference is equal to or more than a predetermined value, perform subsequent data sampling at the first sampling timing. A method of sampling multi-valued recording data, characterized in that: 6. The multi-valued recording data sampling method according to claim 1, wherein a first sampling timing obtained by the sampling timing detecting operation and one cycle of the multi-valued data. Comparing the second sampling timing detected by the detection operation of the sampling timing after the detection, and if the difference is equal to or less than a predetermined value, perform subsequent data sampling at the second sampling timing. A method of sampling multi-valued recording data, characterized in that: 7. The multi-valued recording data sampling method according to claim 1, wherein an absolute value of a difference between two data at predetermined time intervals equal to or less than one cycle of the multi-valued data is calculated. A method of sampling multi-valued recording data, wherein the size is equal to or larger than the multi-level level difference. 8. The multi-valued recording data sampling method according to claim 1, wherein the multi-valued recording data is a positive integer of 4 or more, and A method of sampling multi-valued recording data, wherein the magnitude of the absolute value of the difference between two data at predetermined time intervals equal to or less than the cycle of the value data is equal to or more than the (n-2) value level difference.