Mitsubishi Denki Kabushiki Kaisha

Kihei Ido

Masayuki Ohta

Hideaki Kosaka

Masako Yamada

Kenji Maeno

Ken Onishi

Taketoshi Hibi

Makoto Kumano

Keiji Hatanaka

Ikuo Ohkuma

Shinobu Ueda

Akiyoshi Hirano

Takashi Shiroshita

A data conversion method from m bits of data words into n bits of code words in recording or transmission, in which n is larger than m. A number of bit '0' arranged between one bit '1' and a next bit '1' is restricted to at most 4 in a code string of each code word, and a pair of groups of the n bits of code words corresponding to CDSs (code word digital sum) of two codes +1 and -1 are allowed to correspond to the m bits of data words. One of the two codes +1 and -1 is selectively used according to a DSV (digital sum variation) control signal to convert the m bits of data word into the n bits of code word. A pilot signal formation method using the data conversion method for obtaining a tracking error signal in a magnetic recording and reproducing apparatus, and a rotary magnetic head device for use in a magnetic recording and reproducing apparatus are also disclosed.

Data conversion method, pilot signal formation method using the same

A data conversion method, wherein a sequence of first r-bit datawords is divided into groups of x bits where x is the least common multiple of r and m, an arbitrary first dataword selected from x/r groups of first datawords is divided into x/m, an m-bit second dataword is formed by appending r/(x/m)-bit data, obtained by dividing the first dataword into x/m, to the LSB or MSB side of one or other of the non-divided first datawords, and the word-converted m-bit second dataword is converted to an n-bit codeword (m&lt;n).

Data conversion method and apparatus imbedding pilot signal into

The method and apparatus records/reproduces multiple kinds of digital signals having different data amounts per unit time on a recording medium. The multiple kinds of digital signals are organized into a plurality of blocks. At least two of the multiple kinds of digital signals are organized into blocks having different lengths. A synchronizing signal is appended to each of the plurality of blocks. The synchronizing signal identifies a length of each of the plurality of blocks. This method an apparatus increase the recording rate, and is therefore suitable for higher density recording. In reproduction, synchronization protection is performed for variable synchronization periods based on the length of the blocks being reproduced.

Recording/reproducing apparatus for recording and reproducing multiple

A data conversion apparatus which converts an m-bit data into plural n-bit codes having different CDS values to obtain an intense spectrum at frequencies with a period of p bits has a CDS control signal generator which generates data of a known CDS in codeword with one period which is the least common multiple (q) of n and p, an error detector which detects differences between values of charge in codeword at intervals of (r) bits (where r is the greatest common divisor of n and p) and the data of the known CDS in codeword and detects a sum of absolute values (.DELTA.CDS) of the differences, and a minimum value hold circuit which selects a code having the smallest sum of absolute values (.DELTA.CDS), from the plural n-bit codes having different CDS values.

Data conversion apparatus and encoding apparatus

When recording HD video signals, twice the number of tracks are used as compared to recording the conventional NTSC video signals, and video signals are recorded in the audio sector. HD video signals are encoded with the same number of checks as the error-correcting code of the present video signals, with the number of information symbols being increased. When recording HD video signals and present video signals, these signals are encoded so that the shortest recording wavelength is the same with either signal.

Video signal recording/reproduction apparatus and method for

Method and system using encoded periodic digital sum variation (DSV) as

In program retrieval using a magnetic tape in which programs are classified by index signals recorded on the tape, an image at the beginning of each program is displayed in a list on a multi-screen, and a desired program is directly selected using a count value of index signals. In recording, an index signal is recorded at a starting point of recording. When preparing a multi-screen at the time of reproducing, an image reproduced a predetermined time after detection of an index signal is reduced and stored in a memory.

Recording and reproducing apparatus

M sets of digital data obtained by adding a control bit to an n-bit data string are collected to generate 2.sup.m kinds of m(n+1)-bit data strings, with I-NRZI modulation being applied to these data strings to generate m kinds of I-NRZI modulated data strings and the I-NRZI modulated data strings are subject to spectrum analysis for the desired frequency components, in order to supply one of the I-NRZI modulated data strings as a recording signal based on the result of the spectrum analysis.

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Nagaokakyo, Japan

Kihei Ido