Fujitsu Corporation

Katsuhiko Fukuda

Akiyoshi Uchida

Toru Fujiwara

Masakazu Taguchi

Akihiro Itakura

Kenichi Hamada

Satoshi Furuta

Takanobu Kashiwagi

The invention provides a data recording device comprising: an interval counter; an &#x3b1; counter; and a segment counter, wherein the interval counter and the &#x3b1; counter operate with a clock having a constant frequency which is independent of clock information, the interval counter is reset when division information is detected and, also, is reset and activates the &#x3b1; counter when it reaches a count value corresponding to a segment length, the &#x3b1; counter is reset when the division information is detected and, also, is reset and increments the count value of the segment counter when it reaches a count value corresponding to a predetermined length smaller than the segment length, and the segment counter increments its count value when the division information is detected and outputs a writing inhibition signal when it reaches a count value corresponding to the frame length.

Data recording device

An apparatus for reproducing data includes a branch metric computation unit and a plurality of parallel computation units. Each parallel computation unit includes path metric computation units that compute path metric values based on branch metric values. Path metric memories store the path metric values to be used in a next following path metric computation, and reliability computation units compute path reliability. Modified-path generating units generate an inverted path that is inverse to a path indicated by an output of the reliability computation units as having low reliability. If any one of the modified-path generating units generates the inverted path, a corresponding one of the path metric computation units stores a path metric value corresponding to the inverted path in a corresponding one of the path metric memories as a path metric value to be used in a next following path metric computation.

Data reproducing apparatus avoiding selection of incorrect path

An information recording and reproduction apparatus has a turbo decoder that decodes turbo encoded data. The turbo decoder has a number of likelihood ratio calculation units, forward direction path probability calculation units the number of which is less than the number of the likelihood ratio calculation units, and backward direction path probability calculation units the number of which is less than the number of the likelihood ratio calculation units. The likelihood ratio calculation units calculate in parallel the likelihood ratio for each of a plurality of data blocks. The forward direction path probability calculation units time-divisionally calculate probabilities of the forward direction paths for the data blocks. The backward direction path probability calculation units time-divisionally calculate probabilities of the backward direction paths for the data blocks.

Information recording and reproduction apparatus, optical disk apparatus and data reproduction method

A data reproduction device in conformity to Viterbi decoding includes an inverted-selected path generation part for receiving a selected path and an inverted candidate, selecting and modifying the selected path corresponding to the inverted candidate so as to produce a inverted-selected path that is an inverted version of the selected path, and outputting a number of the inverted-selected paths in parallel, the number corresponding to a number of the inverted candidates selected for the selected path of a predetermined data length and a second candidate data generation part for generating second candidate data from the inverted candidate. The device further includes a data selection part for selecting between the first and the second candidate data based on error detecting results.

Data reproduction device

A clock adjustment device for a data reproduction apparatus includes an edge detection part detecting an edge of a reproduced signal corresponding to a predetermined synchronization pattern based on a state of change of sampled values obtained in synchronism with a clock signal from the reproduced signal, a timing signal output part outputting a timing signal in a given cycle determined by the synchronization pattern from a timing at which the edge of the reproduced signal is detected, and a phase adjustment part adjusting a phase of the clock signal when the edge of the reproduced signal is detected and every time the timing signal is output.

Growing community of inventors

Kato, Japan

Katsuhiko Fukuda