Hitachi, Ltd.

Hitachi Denshi Kabushiki Kaisha

Morito Rokuda

Seiichi Mita

Morishi Izumita

Hidehiro Kanada

Yoshizumi Eto

Masuo Umemoto

Hideo Nishijima

Nobukazu Doi

Michio Masuda

Hiroyasu Ohtsubo

Hitoshi Katayama

Hitoaki Owashi

Kaneyuki Okamoto

Masataka Sekiya

Yuichi Michikawa

Kohji Minabe

Hiroshi Shiono

Yuuichi Michikawa

Masuo Umenoto

Hitoshi Takagi

This invention relates to a method and apparatus for processing a color video signal. The processing method separates an input composite color video signal into a luminance signal and chrominance signal, demodulates the separated chrominance signal into color difference signals, stores the separated luminance signal and color difference signals in a memory, reads out the luminance signal and color differnece signals in units of 1-field period from the memory, implements the extension or reduction of the field period length alternately for every certain number of fields in reading out the luminance signal and color difference signals from the memory thereby to fix the phase relation between a residual chrominance signal component in the luminance signal read out of the memory and a chrominance signal produced by modulating the color subcarrier with the color difference signals read out of the memory, implements an intended signal processing for the readout signals, modulates the color subcarrier with processed color difference signals to produce a chrominance signal, and mixes the chrominance signal with processed luminance signal to produce a composite color video signal.

Method and apparatus for processing a color video signal

A picture synthesizing apparatus in which a main picture is displayed with a part inlaid with a subsidiary picture. The apparatus includes an AGC circuit for regulating the gain of the main video signal and an AGC circuit for regulating the gain of a subsidiary video signal. Alternatively, the chrominance signal level of the subsidiary video signal can be regulated in accordance with the chrominance signal level of the main video signal.

Picture synthesizing apparatus with gain control system

Number data affixed to individual digital data divided into a plurality of data blocks are sequentially read out from a recording medium to be used for determining the write-in positions of the digital data in a memory. For determining the write-in positions of the digital data, the number data of the next write-in position is estimated on the basis of the number data of the current write-in position. Judgment is made as to whether or not the number of times of continuous non-coincidence between the estimated number data and the successively read-out number data exceeds a predetermined setting, and, also judgment is made as to whether or not the number data read out each time falls within a predetermined range. Depending on the results of these judgments, one of the read-out number data and the estimated number data is selected to determine the next write-in position.

Digital data playback system

An apparatus for regenerating original signals comprising: means for introducing a first signal that is produced as an original signal passes through a system that cuts off predetermined frequencies; a first circuit means which produces a third signal obtained on an open loop responsive to said first signal and a second signal which is regenerated from a signal of a predetermined frequency that is cut off by said system; and a second circuit means which regenerates the original signal by converting said third signal into a binary signal.

Apparatus for regenerating original signals

An improved 8-8 mpping table system in digitally and magnetically recording video signals. Video signals coded into natural binary codes consisting of 8 bits are converted into different binary codes consisting of 8 bits constituted by patterns in which a continuous number of the 1's or the 0's does not exceed a predetermined number. In these codes, the continuous number of the 1's or the 0's is so limited that a maximum magnetization interval is reduced in magnetically recording the signals. Therefore, erroneous code is prevented from occurring in reproducing the signals.

Method of magnetically recording coded digital video signals and an

Parity bits (check bits) having a relatively high redundancy are added to upper significant bits of a digital signal, and parity bits having a relatively low redundancy, are added to the lower significant bits of the digital signal. The signal and the parity bits are recorded on a recording medium. The position of an error in a data block group of the lower bits reproduced from the recording medium is estimated as existing in a block in which the error is detected by the check of the data block group of the upper bits, and in the blocks preceding and subsequent to the former. This error correction method is most suitable for a recording and reproduction system of digital video signals.

Method of correcting errors of digital signals in the recording and

The present invention relates to a method and an apparatus for decoding double-encoding codes in which the information to be decoded comprises a first data and a second data. The operation for decoding double-encoding codes is achieved through two stages. A decoder of the first stage checks the first data, and when an error is found in the first data, all symbols of the first data are assumed to be wrong. The first-stage decoder then adds an erasure flag to all symbols to generate erasure symbols. As a result, these erasure symbols include the symbols which are actually erroneous and those which are correct. A decoder of the second stage is used to perform an error correction on the second data. For this purpose, the second-stage decoder detects the number of erasure symbols which are contained in the second data and which are actually erroneous. If the number of actually erroneous symbols does not exceed the maximum number of correctable symbols which can be corrected by the decoder of the second stage, the error correction is effected; otherwise, the decoder detects an error without conducting the error correction.

Method for decoding double-encoding codes and apparatus using the same

In the code modulation system for converting input data levels into an output signal in the form of code words by providing M input levels among N input levels assigned to input data with stairlike code weights on the basis of the input levels, (N-M) input levels which are the difference between said N input levels and said M input levels are respectively disposed near transition points where said stairlike code weight is changed, and the code weights are provided with hysteresis in the ascent process and the descent process of the input data level.

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Katsuta, Japan

Morito Rokuda