Victor Company of Japan, Limited

Kazunari Matsui

Keiichi Kaneko

Takaro Mori

Katsumi Takaoka

Takaaki Saiki

Takumi Hayashiyama

Non-compensation signal points are determined in a two-dimensional plane without considering a signal error caused by digital quadrature modulation. The two-dimensional plane is defined by a real axis and an imaginary axis. The real axis corresponds to real-part signal components. The imaginary axis corresponds to imaginary-part signal components. Compensation signal points are determined in the two-dimensional plane in response to a signal error caused by digital quadrature modulation if the non-compensation signal points are used. The non-compensation signal points and the compensation signal points are point-symmetry. Digital information signal pieces are sequentially assigned to one of the compensation signal points in response to contents of the digital information signal pieces. The digital information pieces are subjected to a modulation process including digital quadrature modulation in response to the above-mentioned assignment to generate a radio-frequency transmission signal.

Method and apparatus for generating transmission signal by processing which includes digital quadrature modulation

Data pieces representative of in-phase components and quadrature components of a digital-modulation-resultant signal are assigned to frequencies for inverse fast Fourier transform. The inverse fast Fourier transform is executed at a predetermined sampling frequency Fs to convert the data pieces into a real-part signal and an imaginary-part signal. Phases of the real-part signal and the imaginary-part signal are shifted. Each of the phase-shifted real-part signal and the phase-shifted imaginary-part signal is divided into a sequence of even-numbered samples and a sequence of odd-numbered samples. A digital quadrature-modulation-resultant signal is generated from further manipulation of the even-numbered and odd-numbered samples.

Method and apparatus for modulation and demodulation related to orthogonal frequency division multiplexing

A first orthogonal-multi-carrier signal is generated through N-point inverse discrete Fourier transform. The first orthogonal-multi-carrier signal has &ldquo;N&rdquo; or less orthogonal multiple carriers, where &ldquo;N&rdquo; denotes a predetermined natural number equal to or greater than 2. Every 1-unit time segment of the first orthogonal-multi-carrier signal is repeated &ldquo;M&rdquo; times to generate every 1-symbol time segment of a second orthogonal-multi-carrier signal. The second orthogonal-multi-carrier signal has a thinned set of &ldquo;N&rdquo; or less orthogonal multiple carriers spaced at M-carrier intervals, where &ldquo;M&rdquo; denotes a predetermined natural number equal to or greater than 2.

Generation and decoding of multi-carrier signal

A DSV (Digital Sum Value) control system for use in conversion of a sequence of m-bit digital data codes into at least first and second sequences of n-bit digital modulation codes using a plurality of modulation tables under the DVD (Digital Video Disc) standards, for example. The DSV control system outputs a sequence of modulation codes produced by selecting, in time sequence, one of the codes of the first sequence or one of the codes of the second sequence according to a select signal SB. The select signal SB is provided based on a DSV control enable flag indicating that DSV control enable codes of the first and second sequences will appear at a following address and a select signal SA indicating which of the DSV control enable codes of the first and second sequences should be selected in order to optimize a DSV of the outputted sequence of modulation codes.

DSV control system

When information signals are recorded on an information signal recording medium formed with circular information signal tracks, the information signals are recorded after being scrambled with scrambling signals of cyclic codes. The period at which the scrambling signal makes a round is determined longer than a time length of an information signal quantity recorded on the maximum recording capacity (e.g., the outermost tracks), or a part of the scrambling signals are used repeatedly. The information signal recording method can remove the correlation between the adjacent tracks, and thereby enable a stable tracking control.

Method and apparatus for recording an information signal with scrambling

Digital modulating method and apparatus are provided which converts m-bit data codes, in sequence, into digital modulation codes each consisting of n channel bits (n&gt;m) to form a modulation code sequence using connection codes. Bit patterns of portions of the modulation code sequence and the connection codes are changed or additional bit patterns are inserted into the modulation code sequence so as to meet given conditions of a minimum transition interval, a maximum transition interval, and a Digital Sum Value. Demodulating method and apparatus performing a reverse modulation operation are also described.

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Yokosuka, Japan

Kazunari Matsui