International Business Machines Corporation

Hiroaki Kubo

Naoyuki Kagami

Masahiro Murakami

Keiichi Okada

Masakuni Okada

Kazuto Yamafuji

Makoto Takekoshi

Takehito Sakuragi

Masahiro Hori

Norio Fujita

Noriaki Asamoto

Hideo Ueno

Katsuyuki Sugita

Kohji Nakase

A situation is circumvented where wireless communication becomes impossible in a wireless LAN system under the influence of a blocking object, noise caused by an electromagnetic wave, or the like. A wireless LAN system comprises: a relay which can communicate with an external system; a master which can communicate with the relay; and a plurality of slaves which can wirelessly communicate with the master, the plurality of slaves including a first group and a second group, the first group comprising an alternative slave having a function of transmitting, when a portion of the slaves cannot receive a synchronization signal from the master, an information signal received from the master to the portion of slaves, and the second group comprising non-alternative slaves and not having the function of transmitting the information signal to the portion of slaves.

Wireless local area network (LAN) system

The present invention enables an image signal processing that can improve color representation of an image signal converted from YCrCb 4:2:2 format to YCrCb 4:2:0 format. An image signal processing apparatusincludes a bufferfor retaining YCrCb 4:2:2 image signals captured by an image signal input, a frame and line recognizerfor determining whether the line from which the YCrCb 4:2:2 image signals are captured is a first line or a second line of an adjacent line pair based on frame and line information on the YCrCb 4:2:2 image signals captured by the image signal input, and a Cr and Cb data correctorfor, if the frame and line recognizerdetermines that the line is the second line, reading YCrCb 4:2:2 image signals for the pixels in the first line at the same horizontal positions as the pixels in the second line from the bufferand correcting Cr and Cb data on the YCrCb 4:2:2 image signals for the pixels at least in the first line of the first and second lines of the line pair based on Cr and Cb data on the captured YCrCb 4:2:2 image signals for the pixels in the second line.

Image signal processing method and apparatus

An apparatus to reduce effects on playback of moving picture data caused by variations in data transmission rate that occur on a communication line, a receiving and playing back apparatus includes a receiver for receiving moving picture data transmitted over a communication line; playback modules for playing back the received moving picture data; a second buffer for temporarily storing the moving picture data received by the receiver and outputting the stored moving picture data at a desired speed; and a first buffer for providing the playback modules with moving picture data required for playback processing.

Apparatus for receiving and playing back data

A format conversion circuitincludes a FIFO memoryfor writing and reading video data VD in synchronization with a sampling clock CK, a header generation circuitfor generating an MPEG2-TS packet header, and a synchronous timing detection circuitfor detecting a horizontal synchronizing signal for the video data VD. The format conversion circuitalso includes a counterwhich counts the number of bytes of packet header and the number of bytes of video data VD, and a switchwhich selects the packet header until the counted number of bytes reaches four bytes, and then selects the video data read out of the FIFO memory

Format conversion circuit

Provides methods and apparatus to reduce effects on playback of moving picture data caused by variations in data transmission rate that occur on a communication line, a receiving and playing back apparatus includes a receiver for receiving moving picture data transmitted over a communication line; playback modules for playing back the received moving picture data; buffer B for temporarily storing the moving picture data received by the receiver and outputting the stored moving picture data at a desired speed; and buffer A for providing the playback modules with moving picture data required for playback processing.

Method and apparatus for receiving and playing back data

Object To provide a highly accurate and stable pulse width modulation (PWM) pulse signal generation device compatible with high resolution images without increasing a basic frequency of an external oscillation circuit. Solving Means A PWM pulse signal generation device includes a first PLL control circuita ring oscillatorin which a plurality of basic delay elements are serially connected, and a delayed pulse generation circuit constituted by a delay ratio adjusting circuitand a delay circuit. The delay circuitis formed by setting one adjustment delay element having a delay ratio R that is adjusted by the delay ratio adjusting circuitat a first stage and a plurality of serially connecting basic delay elements. An output pulse signal from each delay element of the ring oscillatorand an output pulse signal from each delay element of the delay circuithaving a delay amount corresponding to the delay ratio are superimposed to perform pulse width modulation, whereby output pulses having various pulse widths can be generated.

Delay ratio adjusting circuit, delayed pulse generation circuit, and pulse width modulation pulse signal generation device

Wireless data communication method and apparatus using two electromagnetic signals having different polarizations. Codes related to relative values of the amplitudes of the two signals are generated in correspondence with data to be transmitted. The signals are modulated according to the codes using phase shift keying and amplitude shift keying. The amplitude shift keying modulates the two electromagnetic signals by changing the difference between their two amplitudes in accordance with data encodings. The two signals are transmitted to receiver, which decodes the phases and relative amplitudes to obtain the codes, and reproduces the data from the obtained codes.

Polarization modulation with amplitude differential

An apparatus for recording and reproducing digital data, which is capable of recording digital broadcast data while reproducing previously-recorded digital broadcast data is provided. An apparatusfor recording and reproducing digital data, which is capable of recording MPEG2-PES datagenerated from record control meansin recording meansby controlling the record control meansand reproduction control meansby time division control meanswhile reading the MPEG2-PES datarecorded in the recording meansby reproduction control means

Apparatus and method for recording and reproducing digital data

Satellite receiver and method and apparatus for adjusting the direction of satellite dish antenna

A method and device are provided for correcting an amplitude of a synchronizing signal. A pedestal voltage, Vped, (i.e., a reference level) may be detected which repetitively occurs at the same period as a synchronizing signal of an input composite video signal. A reference voltage, Vsync, may be generated corresponding to an amplitude of the synchronizing signal which meets a standard for the input composite video signal. A DC voltage, Vh, may be generated having a voltage level corresponding to a tip or peak level of the synchronizing signal which meets the standard for the input composite video signal based on the pedestal voltage, Vped, and the reference voltage, Vsync. The DC voltage Vh and the composite video signal may be switchably output in synchronism with the synchronizing signal extracted from the composite video signal.

Method for correcting amplitude of synchronizing signal of composite video signal and device therefor

When short MPEG2 data transfer streams, such as those used for commercials, are sequentially distributed within a short period of time, a decoder method synchronizes the transfer and prevents accumulation of data in a buffer and data losses. The synchronization method extracts sync data originating at the transmission source from a received data stream; acquires sync data for a decoder based on a reference clock; compares the sync data originating at the transmission source with the sync data for the decoder in order to sequentially obtain control values, sequentially updates the frequency of the reference clock for transfer synchronization for the received data stream; determines whether or not a data stream that differs from the received data stream has been received; and employs, when a different data stream has been received, the reference clock obtained when the received data stream has been received, to initiate transfer synchronization for the different data stream.

Synchronization method and decoder

The present invention is intended to provide a method for putting an optical head in a stationary state, and an optical disk drive apparatus for doing so without the need of a dedicated sensor for detecting an absolute position of the optical head in the radial direction of the optical disk or a device for fixing the head.

Method for putting an optical head in a stationary state and optical

An optical disk drive apparatus operable under track following mode and seek mode wherein, upon the detection of a track following operation error, a seek operation is initiated for seeking a new target track at a predetermined number of tracks distant from the current track. The seek operation is controlled to follow a velocity profile thus regaining control over an optical head that may have been jolted into an out of control velocity when the track following error occurred. The velocity profile provides for a reduced velocity as the target track is approached. The new target track is selected at a relatively large number of tracks distant from the current track if the head velocity is high and at a relatively small number of current tracks if the head velocity is low. If the current track is sensed to be an outer track, the new target track is selected toward the inner track and if the current track is sensed to be an inner track, the new target track is selected to be an outer track.

Apparatus for controlling a optical disk drive

An optical disk drive includes a gain control for controlling the gain of a focus servo loop in response to the seek velocity of an optical head. At a low seek velocity, the focus servo gain is reduced to minimize the influence of beam scattering on the groove of an optical disk onto a focusing error signal (FES) and a tracking error signal (TES).

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Shiga-ken, Japan

Hiroaki Kubo