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Modulation/demodulation method, demodulation apparatus, and code modulation method

A technology of modulation, demodulation and coding, applied in coding, coding components, code conversion, etc., can solve the problems such as the inability to effectively utilize the resolution of the recording medium and the difficulty of coding judgment.

Inactive Publication Date: 2014-12-03
HITACHI-LG DATA STORAGE +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, when the binary data to be recorded (referred to as user data in this specification) is directly recorded in correspondence with the presence or absence of recording marks, the recorded bit interval is smaller than the diameter of the light spot, and due to the interference between adjacent bit codes, Code discrimination becomes dramatically difficult
As a result, the resolution of the recording medium cannot be effectively utilized

Method used

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  • Modulation/demodulation method, demodulation apparatus, and code modulation method
  • Modulation/demodulation method, demodulation apparatus, and code modulation method
  • Modulation/demodulation method, demodulation apparatus, and code modulation method

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Embodiment Construction

[0060] (Asymmetric Modem)

[0061] Among the technical problems described above, countermeasures are explained based on the present invention for demodulation errors caused by the occurrence of burst errors. First, use an asymmetric transformation. use Figure 7 An example of the pattern shown is described. In this example, a burst error occurs in which all edges in the channel word are shifted to the right by 1 channel bit. If the channel bit pattern generated as a result of a burst error is recorded in the conversion table, the demodulation result contains errors but the demodulation process after that part can continue. The problem is that the channel bit pattern resulting from the burst error is not recorded in the conversion table, so the demodulation process cannot continue if it remains in this state. So, if Figure 9 As shown, this problem can be solved by simultaneously searching the auxiliary pattern set 41 whose elements are the auxiliary pattern 40 which is a ...

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Abstract

Patterns that might be generated due to a burst error are prepared beforehand. These patterns are formed by shifting all “1”s in an original channel word. A list of these patterns generated as described above is retrieved in parallel with a general conversion table during demodulation. When the demodulation is interrupted due to the burst error, the result of the retrieval of the previous pattern is referred to, and when there is a hit, the error is regarded as the burst error of the original channel word, and the demodulation is continued.

Description

technical field [0001] The present invention relates to signal modulation and demodulation method, demodulation device and code modulation method, especially relates to the method of using light to record and reproduce information with high density. Background technique [0002] Part of the terminology in the following explanations uses the expression method used in Blu-ray (registered trademark) Disc (BD). These terms may use other names in systems other than BD. However, those skilled in the art should be able to easily understand. [0003] There are several ways to increase the recording capacity of an optical disc, one of which is coded modulation as described in Patent Documents 1 and 2. This scheme has been used in BD et al. For coded modulation, several effects can be expected. Among them, the line recording density improvement effect is one of the most expected effects, and run-length limited coding is known as a code used for this purpose. [0004] In an optica...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B20/14
CPCH03M13/6325H03M5/14H03M7/40H03M7/6052
Inventor 菊川敦
Owner HITACHI-LG DATA STORAGE