Hitachi, Ltd.

Other

Hitachi Video Engineering, Incorporated

Nippon Victor Kabushiki Kaisha

Masaharu Kobayashi

Takao Arai

Takaharu Noguchi

Hiroo Okamoto

Keizo Nishimura

Takashi Hoshino

Toshifumi Shibuya

Hiroyuki Kimura

Nobutaka Amada

Yasufumi Yumde

Hiromichi Tanaka

Takashi Takeuchi

Shigeru Yamazaki

Kuniaki Miura

Tsutomu Noda

Masami Nishida

Michio Masuda

Hiroaki Takahashi

Masahiro Ito

Shigeki Inoue

Harukuni Kobari

Chitoshi Hibino

Toshio Tanizoe

Hiroshi Endoh

Taihei Nakama

Yasufumi Yunde

Tsuneji Koshikawa

Yukio Nishimura

Eiji Okubo

Kazumasa Oiso

In an information recording/reproducing apparatus for recording/reproducing a digital audio signal on/from a magnetic medium, a modulator/demodulator for modulating/demodulating the digital signal by offset quadrature phrase shift keying (O-QPSK). This technique is particularly applicable to the multi-layer recording of video and audio signals in a video tape recording/reproducing system and has the advantage of avoiding interference between the recorded digital audio and video signals at the time of reproduction.

Magnetic recording/reproducing method and apparatus

A PCM audio signal recording and reproducing apparatus samples an audio signal with a sampling frequency having an asynchronous relation to a field frequency of a video signal; converts it to a PCM signal, adds error detection/correction data to a predetermined number of PCM data, forms a data frame by those signals, modulates it in accordance with a predetermined modulation system, and records the audio signal together with the video signal or just the audio signal on a record medium by using a rotary head type scanner which is controlled so as to have a synchronous relation to the field frequency of the video signal. A digital signal processing circuit having a memory of a predetermined capacity is provided, and the number of digital data to be recorded in one data frame is varied in accordance with a difference between the number of input data of the digital audio signal to the digital signal processing circuit and the number of output data supplied to the record medium for recording. In the recording mode, the PCM audio signal is sectioned into blocks, a data block address signal is added to each block to indicate a relative order of a block to the other blocks and is completely added in one track, certain number of blocks are combined to form a block set for processing signals, and an identification signal completing in the block and an interleave block address signal for indicating a relative order to other blocks are added to each block.

Method and apparatus for PCM recording and reproducing an audio signal

A rotary-head type magnetic tape recorder for recording a video signal and an audio signal on a magnetic tape by means of a rotary head controlled on the basis of the video signal. Difference is determined between a rate at which the digital audio signal is recorded on the recording medium and which is determined by the video signal and a rate of input data determined by a sampling frequency of the audio signal for a number N of samples of the digital signal to be included within one field period synchronized with the video signal. The number of samples for one field of input data is set by preparing on the basis of the result of detection of the difference in rate a first field containing a number of samples greater than the number N within and a second field containing a number of samples smaller than the number N. Blocks for recording the PCM audio signal on the recording medium are prepared by adding a first error detection/ correction code to the audio signal for every n symbols, while the symbols are imparted with amounts of delay differing from one another and subjected to diagonal incomplete interleave for thereby adding a second error detection/correction code. After addition of a block synchronizing signal, recording is performed on the tape. By adopting the variable fields, matching can be attained between the asynchronous audio and video signal fields. Reproduction capability notwithstanding of burst error is enhanced by incomplete diagonal interleave. Difference in time lag between the video signal and the audio signal involved in the reproduction thereof can be suppressed to a minimum.

Rotary head type recording/reproducing method and apparatus for

The present invention relates to an apparatus for recording a digitized signal. If a recording apparatus is switched from a recording mode to a non-recording mode and then switched from the non-recording mode to a recording mode, there is produced a portion between two records where the records are not continuous. When such a portion is reproduced, abnormal data come to be reproduced because of existence of discontinuity between the prior and subsequent data. And, if a digital audio signal is similarly recorded, it follows that an abnormal sound is generated when such a portion is reproduced. Then, by recording an anti-format signal in the discontinuous portion, the reproduction of abnormal data or generation of abnormal sound can be prevented from occurring.

Apparatus for recording digital signal

A rotary head type digital signal recording and/or reproducing apparatus wherein for 1/2 speed recording and/or reproducing from a magnetic tape, a tape feed speed is decreased to 1/2 times the normal speed, and a recording/reproducing interval becomes 2 times that of the normal mode of operation utilizing at least two rotary heads mounted at adjacent positions on a rotating cylinder with one of the rotary heads having a plus azimuth angle and the other having a minus azimuth angle. For 2 times speed recording/reproducing, a tape feed speed increases to 2 times the normal speed, and a recording/reproducing interval becomes 1/2 that of the normal mode of operation utilizing at least two rotary heads mounted on a rotating cylinder at opposite positions of a rotary axis of the cylinder, with one of the two rotary heads having a plus azimuth angle and the other having a minus azimuth angle.

Rotary head type digital signal recording and/or reproducing apparatus

A method and an apparatus for recording and reproducing a PCM audio signal either alone or together with a video signal, using a rotary-head type scanner. An analog audio signal is converted into a digital signal having a predetermined number of quantization bits in each predetermined sampling period. The digital signal is recorded on a recording medium such as a magnetic tape, and an analog audio signal is reproduced from the digital signal reproduced from the recording medium. In the reproducing mode, the signal reproduced from the tape is written into a memory where error detection, correction and deinterleaving are carried out, and the signal is then read from the memory and applied to a D/A converter. The write rate from the memory depends on the video field period, and the read rate depends on the sampling period. Accordingly, the difference between the write address and the read address of the memory depends on the difference between the field period and the sampling period. By changing a master clock, which defines the sampling period controlled by the read address, in accordance with the address difference, the difference between the video signal field period and the audio signal sampling period can be controlled and compensated.

PCM recording and playback with variable read and write speeds

In a recording and reproducing apparatus wherein a video signal and an audio signal are recorded on the same recording track, a signal subjected to a quadrature differential PSK modulation with PCM audio signal is generated as an audio recording signal. The audio recording signal is disposed between occupied bands of FM luminance signal and down converted chrominance signal in a video recording signal and also recorded on a track where the video recording signal is to be recorded.

Apparatus for recording and reproducing video signal and digital signal

When a PCM signal having a sampling frequency of 32 KHz, a quantization of 12 bits per sample, and 4 channel is to be recorded onto tape, the PCM signal undergoes, prior to being recorded onto the tape, such predetermined data dispersion that burst errors incurred in the reproduction operation may be compensated.

Method and apparatus for recording and/or reproducing PCM signals

A PCM signal recording and reproducing apparatus comprises first and second memory circuits, in which PCM signals are read and written using the first memory circuit, while PCM signals stored in the second memory circuit are error-corrected. At the end of writing by the first memory circuit, the first and second memory circuits are interchanged to read the error-corrected PCM signals stored in the second memory circuit. The read-out error-corrected PCM signals are then recorded on another magnetic tape.

PCM signal recording and reproducing apparatus including simultaneous

In a method of transmitting digital data including the steps of constructing one block by a plurality of digital data, constructing one frame by a plurality of blocks, adding two kinds of mutually different error detection and correction codes to these blocks and transmitting these digital data together with the codes that are added, the digital data are not interleaved, only the error detection and correction codes are interleaved and these interleaved codes are added to the digital data.

Method of transmitting digital data in which error detection codes are

In PCM signal recording method and apparatus using rotary heads for converting two channels of autio PCM signals each consisting of 12-bit words to a data consisting of 8-bit words and recording the converted data, there is provided means for converting the PCM signals to two data each consisting of eight high order bits of each of two words of the PCM signals, and an 8-bit data consisting of the remaining four low order bits of the respective words. The converted PCM data are recorded on a record tape in a format such that PCM signals having i words/channel which are to be recorded on first and second tracks are divided into a first half and a second half, even data in the first half and odd data in the second half constitute the data to be recorded on the first track, and odd data in the first half and even data in the second half constitute the data to be recorded on the second track.

Method and apparatus for recording PCM signal

In a recording operation by a rotary head type PCM recording/reproducing apparatus including at least two magnetic heads, the odd-numbered sample data and the even-numbered sample data are discriminatively extracted and stored. The stored data corresponding to an amount of data outputted from the A/D converter within a predetermined time is selectively read out and supplied to the two heads to thereby record the data in such a manner that the odd-numbered data and the even-numbered data are recorded separately on a track basis or alternatively recorded separately on a preceding half and a succeeding half of each track. The error detecting and correcting code is prepared on the basis of the data to be recorded in each track. In reproduction of the recorded data, upon detection of a drop-out of the data from one of the two heads, the drop-out data is corrected through interpolation procedure to thereby reconstitute the original analog signal.

Rotary head type PCM recording and reproduction method and system

Error detection/correction codes appended to a recording signal for a PCM recorder are so arranged as to ensure detection and/or correction of a dropout or error of a data block address in the reproduction of the recording signal. In recording digital signals on a recording medium, the digital signals are formatted in n-word blocks, each block further including a sync signal for providing a reference timing for the reproduction of the signal, control data related to the digital signals, a data block address for identifying the block of n-words, an error detection code for detecting an error in the control data and the block address, and an error detection/correction code for error detection and/or correction for the block address and the n-words. A recording system includes an error detection/correction code generating circuit which generates error detection/correction codes using a Reed Solomon code or b-adjacent code. The generated error detection/correction codes are combined by a multiplexer so that a recording signal is arranged, and recorded on the recording medium.

Method and apparatus for recording digital signals

This invention relates to an error correction upon reproduction of digital signals. The error correction is performed by decoding code words such as cross-interleaved Reed Solomon codes, in which first code blocks are formed by a plurality of information words which are in the first arrangement state and a plurality of first check words which are produced by codes associated with the plurality of information words with a Hamming distance of d.sub.1, and second code blocks are formed by a plurality of information words and a plurality of first check words which are in the second arrangement state and which consist of the said plurality of information words and the said plurality of first check words which are respectively included in the different first code blocks, and by a plurality of second check words which are produced by codes associated with the plurality of information words and the plurality of first check words with a Hamming distance of d.sub.2. At the first decoding stage, errors are detected and at the same time the flags indicative of the decoding states are added with respect to the second code blocks. At the second decoding stage, in accordance with the contents of the flags and on the basis of a combination of p.sub.2 and q selected from their combinations satisfying 2p.sub.2 +q.ltoreq.d.sub.1 -1, errors are detected and errors of p.sub.2 words are corrected and erasures of q words to which the flags were added are corrected with respect to the first code blocks.

Error correction method and system

The recording area of the magnetic tape is divided into a first area for recording a PCM converted audio signal and a second area for recording a PCM converted video information. In recording the audio signal and the video information which have been separately PCM converted, the magnetic tape is wrapped around the rotary heads so that a wrap angle of each of said first and second areas is less than 90.degree. with respect to the rotary heads of a predetermined diameter.

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Yokohama, Japan

Masaharu Kobayashi