Sony Corporation

Koninklijke Philips Corporation N.v.

Yoshihide Shinpuku

Toshiyuki Nakagawa

Tatsuya Narahara

Gijsbert Joseph Van Den Enden

Kornelis A Schouhamer Immink

Kosuke Nakamura

Josephus A H M Kahlman

Satoru Higashino

Hiroyuki Ino

A DSV control bit determining/inserting unitinserts DSV control bits for execution of DSV control into an input data string and outputs the data string including the DSV control bits to a modulation unitThe modulation unitconverts the data string with a basic data length of 2 bits into variable length code with a basic code length of 3 bits in accordance with a conversion table and outputs the code resulting from the conversion to a NRZI encoding unitThe conversion table used by the modulation unitincludes substitution codes for limiting the number of consecutive appearances of a minimum run to a predetermined value and substitution codes for keeping a run length limit. In addition, the conversion table enforces a conversion rule, according to which the remainder of division of the 'count of an element in a data string by 2 having a value of 0 or 1 shall always be equal to the remainder of division of the '1' count of an element in the code resulting from conversion of the data string by 2.

Modulation apparatus/method, demodulation apparatus/method and program presenting medium

How to record and play back data at a high line density. A DSV control bit determining/inserting unitinserts DSV control bits for execution of DSV control into an input data string and outputs the data string including the DSV control bits to a modulation unit. The modulation unitconverts the data string with a basic data length of 2 bits into variable length code with a basic code length of 3 bits in accordance with a conversion table and outputs the code resulting from the conversion to a NRZI encoding unit. The conversion table used by the modulation unitincludes substitution codes for limiting the number of consecutive appearances of a minimum run to a predetermined value and substitution codes for keeping a run length limit. In addition, the conversion table enforces a conversion rule, according to which the remainder of division of the '1' count of an element in a data string by 2 having a value of 0 or 1 shall always be equal to the remainder of division of the '1' count of an element in the code resulting from conversion of the data string by 2.

A DSV control bit determining/inserting unit inserts DSV control bits for execution of DSV control into an input data string and outputs the data string including the DSV control bits to a modulation unit. This modulation unit converts the data string with a basic data length of 2 bits into variable length code with a basic code length of 3 bits in accordance with a conversion table and outputs the code resulting from the conversion to a NRZI encoding unit. The conversion table used by the modulation unit includes substitution codes for limiting the number of consecutive appearances of a minimum run to a predetermined value and substitution codes for keeping a run length limit. In addition, the conversion table enforces a conversion rule, according to which the remaineder of division of the '1' count of an element in a data string by 2 having a value of 0 or 1 shall always be equal to the remainder of division of the '1' count of an element in the code resulting from conversion of the data string by 2.

How to record and play back data at a high line density. A DSV control bit determining/inserting unit inserts DSV control bits for execution of DSV control into an input data string and outputs the data string including the DSV control bits to a modulation unit . The modulation unit converts the data string with a basic data length of 2 bits into variable length code with a basic code length of 3 bits in accordance with a conversion table and outputs the code resulting from the conversion to a NRZI encoding unit . The conversion table used by the modulation unit includes substitution codes for limiting the number of consecutive appearances of a minimum run to a predetermined value and substitution codes for keeping a run length limit. In addition, the conversion table enforces a conversion rule, according to which the remainder of division of the &ldquo;1&rdquo; count of an element in a data string by 2 having a value of 0 or 1 shall always be equal to the remainder of division of the &ldquo;1&rdquo; count of an element in the code resulting from conversion of the data string by 2.

A DSV control bit determining/inserting unit inserts DSV control bits into an input data string and outputs the string including the DSV control bits to a modulation unit which converts the string with basic data length of 2 bits into variable length code with basic code length of 3 bits in accordance with a conversion table and outputs the code resulting from the conversion to a NRZI encoding unit. The conversion table includes substitution codes for limiting the number of consecutive appearances of a minimum run and substitution codes for keeping a run length limit. The conversion table enforces a conversion rule: the remainder of division of the &ldquo;1&rdquo; count of an element in a data string by 2 having a value of 0 or 1 equals the remainder of division of the &ldquo;1&rdquo; count of an element in the code resulting from conversion of the data string by 2.

According to the present invention, in the demodulating device, demodulating method and transmitting medium, a channel bit sequence of a variable length code having a minimum run d of 1 or more was decoded to a data sequence, and a code assigned to limit the minimum run d from repeating a predetermined number of times in the channel bit sequence of the variable length code was decoded to a data sequence. Design is therefore easier from the viewpoint of clock reproduction. When all the elements in the table contain a &ldquo;1&rdquo; representing an edge, data can be decoded more reliably. Further, when omissions are made in the codes in the table up to d bits from the code sequence lengths of the restriction lengths, data can be decoded more reliably. Thus, a clock is stably reproduced.

Demodulating device, demodulating method and transmission medium

The present invention relates to an apparatus for azimuth-recording data on a magnetic recording medium. Heads (13a) and (13b) having azimuth angles different from each other are used and data are recorded on and reproduced from a plurality of adjacent tilted recording tracks on a magnetic tape T. A recording-system encoder (23) converts data to a code sequence in which null points of frequency spectrums are respectively provided at null points of waveform equalization characteristics of partial responses such as PR1, PR4, etc. For example, record-coding using a 8/10MSN code is performed. A reproduction-system equalizing circuit (28) performs waveform equalization based on the partial responses. Further, a data detector (29) detects the data by a Viterbi coding method for executing state transition during which the characteristic of the code sequence is adopted. Azimuth-recording in a narrow track width can be easily achieved while a reduction in effective recording speed due to an increase in the azimuth angle is being controlled.

Azimuth magnetic recording and reproducing apparatus and method

It is intended to reduce the rate of occurrence of prediction value judgment errors. Where a prediction value x'.sub.n-1 of a 1-clock preceding code is 0, a judgment circuit 1 outputs a value '1' as a prediction value x'.sub.n if a reproduction signal value y.sub.n sampled at time n is greater than or equal to a threshold value .eta. that is supplied from a threshold value generating circuit 6, and outputs a value '-1' as the prediction value x'.sub.n if y.sub.n &lt;.eta.. Where x'.sub.n-1 is not 0, the judgment circuit 1 outputs a value '0' as the prediction value x'.sub.n. Therefore, the control circuit 1 outputs a value '0' every other clock as a prediction value. During the interval between the first two clocks, the threshold value .eta. is set at 0. Then, when supplied with codes of a given pattern that are arranged at the start, a switch 2 selects the prediction value x'.sub.n that is supplied from the judgment circuit 1. An operation circuit 16 calculates a phase error .DELTA..tau..sub.n from the prediction value x'.sub.n and the sampled value y.sub.n. On the other hand, an operation circuit 17 calculates a level error .DELTA..gamma..sub.n from the prediction value x'.sub.n and the sampled value y.sub.n.

Information detecting apparatus and method

In a modulation processing unit, m bits of input data are converted to an n bit fixed length code. In an RML conversion unit, a restriction code which limits a minimum run d in a channel bit sequence after converting the fixed length code from repeatedly occurring a predetermined number of times, is converted to a data sequence. A clock is stably reproduced.

Modulating device, modulating device, demodulating device, demodulating

Clock is reproduced stably. If data (limiting code) containing a plurality of consecutive minimum inversion interval Tmin is contained in the data inputted from a shift register, a Tmin consecution limiting code detection unit detects such consecutive interval. A constraint length judgement unit judges the constraint length i to be the constraint length corresponding to the code for limiting the constraint length i when a detection signal is inputted from the Tmin consecution limiting code detection unit, and outputs the judged constant length to a multiplexer. The multiplexer selects the output of a converter corresponding to the constraint length supplied from the constraint length judgement unit out of converters 14-1 to 14-r, and supplies the selected output to a run detection processing unit through a buffer.

Device and method for modulation and transmission medium

A method for recording and/or reproducing a signal in which three regions of a magnetization region in which magnetization is effected in a certain direction, a magnetization direction in which magnetization is effected in the opposite direction to that of the former region and a random magnetization region in which magnetization is effected randomly are arranged on a recording medium and digital data are recorded in correspondence with the three regions. Upon reproduction, a calculation is effected by using a reproduced signal and an isolated waveform information derived from the recording medium, thereby obtaining anticipated data whose most likelihood value is high, and this anticipated data is employed as detected data. Accordingly, a large reproduced output can be obtained in accordance with the change of magnetization, and freedom of the code itself can be increased, thereby improving the recording linear density as compared with the prior art.

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Tokyo, Japan

Yoshihide Shinpuku