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Maximum likelihood decoder and information reproducing device

A maximum likelihood and decoding device technology, applied in information storage, record information storage, digital recording/reproduction, etc., can solve problems such as failure to work normally, and achieve the effect of ensuring normal work

Inactive Publication Date: 2009-03-25
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] However, in the above-mentioned existing maximum likelihood decoding devices, oversampling (oversampling) is the premise. Therefore, there is the following problem: when undersampling (undersampling) occurs due to some chance, it cannot work normally.

Method used

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  • Maximum likelihood decoder and information reproducing device
  • Maximum likelihood decoder and information reproducing device
  • Maximum likelihood decoder and information reproducing device

Examples

Experimental program
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no. 1 approach

[0060] FIG. 1 shows a schematic diagram of a read channel (read channel) 100 as an information reproducing apparatus according to a first embodiment of the present invention. In this figure, digital data is recorded on an optical disc 101 . In the read channel 100, the recorded data and the clock synchronized with the recorded data are extracted. In addition, in this embodiment, although the optical disk 101 was used for the description, it is not limited to this optical disk 101, and the present invention can also be applied to magnetic disks and magneto-optical disks, or wireless communication and wired communication.

[0061] Next, the operation of the read channel 100 will be described. The flow of signals will be described in order. Digital data recorded on the optical disc 101 is read by an optical pickup (reader) 102, and output as an analog signal including recording timing information. The analog front end (analog waveform shaping unit) 103 performs amplitude adjust...

no. 2 approach

[0081] Next, a second embodiment of the present invention will be described.

[0082] Fig. 4 shows the internal structure of a Viterbi decoder 109' which is an information reproduction apparatus according to a second embodiment of the present invention.

[0083] In the Viterbi decoder 109' in this figure, a configuration is shown in which the vitctrl signal in FIG. 2 is used as an under sampling signal, and an over sampling signal (second selection signal) for notifying that recording data has been oversampled is input. , when the over sampling signal is received, the branch metric calculation method, the path metric calculation method, and the data signal calculation method in the branch metric calculation units 202 to 204, the path metric calculation unit 208, and the survivor path management unit 209 are changed, and Stop these parts from working.

[0084] Therefore, in this embodiment, it is possible to ensure normal operation not only when the recording data is undersamp...

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Abstract

In a maximum likelihood decoder, selectors (205 to 207) do not nay branch metric from branch metric calculating sections (202 to 204) when an undersampling occurs and select ''0'' values, and a path metric calculating section (208) calculates a path metric according to the ''0'' values and a path selection signal. In consideration of occurrence of undersampling that the selectors (205 to 207) select ''0'' value, an input signal wsdt_d to be subjected to maximum likelihood decoding and inputted into the branch metric calculating sections (202 to 204) is adjusted into a signal delayed by corresponding several clocks at the occurrence of undersampling. Therefore, even at the occurrence of undersampling, a correct decoding result is obtained, and thus normal operation is ensured.

Description

technical field [0001] The present invention relates to a Maximum Likelihood Decoder (Maximum Likelihood Decoder) using a Viterbi Algorithm (Viterbi Algorithm) and an information reproduction device having the Maximum Likelihood Decoder. Background technique [0002] Heretofore, as such a maximum likelihood decoding device, a maximum likelihood decoding device employing a synchronous sampling method is known. This method controls the sampling clock so that its frequency and phase are synchronized with the channel clock even if the initial state is shifted. [0003] FIG. 6 shows the overall configuration of a maximum likelihood decoding apparatus of the synchronous sampling method. In this figure, the input signal wsdt_d of the maximum likelihood decoding target is input to a plurality of branch metric (branch metric) calculators 402 to 404 to calculate branch metrics, and then these branch metrics are input to the The path metric calculation unit 408 calculates the path me...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B20/14H03M13/41
CPCG11B20/14G11B20/10009G11B20/10222H03M13/6569G11B20/10037G11B20/10296H03M13/4107H03M13/6577
Inventor 山本明
Owner PANASONIC CORP