Fujitsu Corporation

Kenzo Kobayashi

Takanori Iwamatsu

Takayuki Ozaki

Tomonori Gotoh

Hiroyuki Kiyanagi

Takehiko Fujiyama

Yasutaka Umemoto

Toshio Tamura

Toshio Kawasaki

Katsumi Tanaka

Takafumi Edanami

Masaki Miura

Yoshihito Aono

Kazuyuki Inomoto

Mitsuyo Hasegawa

Toshihiro Yamanaka

Noboru Matsubara

Takeshi Yagi

Toshiyuki Takizawa

Yutaka Iwagaki

Kazushi Suganuma

Hiroto Shingai

Yuitsu Ogata

Kazuyoshi Yamauchi

Hisao Narita

Takahiko Terakado

Disclosed is a network system capable of transferring data at a high speed between multicast-supported networks via a L2 network. The network system includes a multicast-unsupported L2 network, two multicast-supported network, two gateway devices for connecting one of the multicast-supported networks to the multicast-unsupported L2 network, and each of witch is capble of assembling, when a multicast data packet is transmitted from the side of the multicast-supported network, a L2-network packet in which a destination MAC address of the multicast data packet is translated into a MAC address of the other gateway device, and transmitting the L2-network packet over the L2 network.

Gateway device connecting multicast-supported network to multicast-unsupported L2 network

A multicast network system is provided with a multicast network unit that delivers data between independent multicast network domains. The multicast network unit includes an extraction part for extracting a multicast delivery destination address from received data, a holder part for holding conversion data where the multicast delivery destination address corresponds to a delivery source address, and a judgment part for judging whether the multicast delivery destination address is held and outputting the result of a judgment. The multicast network unit also includes a filtering part which, when the result of the judgment is holding, converts the multicast delivery source address to an arbitrary delivery destination address and, when it is non-holding, discards the received data. The multicast network unit further includes a transmitter part for transmitting data containing the converted multicast address to the domain.

Multicast network unit, multicast network system, and multicast method

A distortion compensating device provided in a receiver for compensating distortion which is added to a signal in a transmission path. The signal is generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram. The device includes a signal-point-position averaging circuit for producing an average signal point for each of a plurality of distributions of received signal points in the signal space diagram. A discrimination circuit in the device discriminates the average signal point closest to a received signal point from other average signal points in the signal space diagram.

Distortion compensating device

A video display control method comprises generating camera operation information concerning an operation of a camera operated by remote control, transmitting data of video captured by the camera and the camera operation information to a control apparatus via a network; and processing the data of the video based on the camera operation information to display an image of the video at the control apparatus.

Image display control system reducing image transmission delay

A method and an apparatus for transmitting data in a linear-type or ring-type network structured by a plurality of nodes and both-way transmission lines each connecting between adjacent nodes includes that each node operates as a left TE, a right TE, or an IE. The left and right TEs prepare token packets each including a transmission right and packet trailers each including data packet storage area. The left TE transmits the packet trailers on a right direction line of the both-way transmission line.

Method and apparatus for transmitting data in a linear-type or ring-type network

A plurality of image transmitting apparatuses are connected to the image transmitting side of a transmission line, a plurality of image receiving apparatuses are connected to the image receiving side of the transmission line, and a plurality of logical channels are set on the transmission line. A predetermined logical channel is fixedly allotted to each image receiving apparatus, and each image transmitting apparatus is provided with a function of transmitting an image to an image receiving apparatus through any logical channel. Each image transmitting apparatus transmits an image to a designated image receiving apparatus through a predetermined logical channel.

Image transmission method and image transmission system

A first camera having a fish-eye lens and a second camera having a fish-eye lens are disposed with the respective fish-eye lenses faced with each other. An image pick-up range of the first camera and an image pick-up range of the second camera are partially overlapped, and only a relatively narrow area at the backside of each camera becomes a blind area. A processor sets a frame F in the image pick-up area of the first camera and the image pick-up area of the second camera respectively corresponding to a set monitoring range. The image data within these frames F are taken out and distortions of the image due to the characteristics of the fish-eye lenses and are eliminated to obtain first and second transformed frame data. These transformed frame data are combined by an image combining unit to obtain image data corresponding the monitoring range free from any gap. The combined image data is displayed in a monitor through a PC

Monitoring system and monitoring method

The invention provides an automatic delay equalizer and an automatic delay equalization method which can detect a delay characteristic (delay distortion) of an input signal and automatically compensate for the delay characteristic. The equalizer includes an inclination delay equalization section for compensating for the delay characteristic of the input signal in accordance with an inclination delay characteristic, and a control section for discriminating a direction of variation of a value of a first one of a pair of digital demodulated signals of the input signal, detecting error information from a second one of the digital demodulated signals which is orthogonal to the first signal and outputting a control signal for the inclination delay equalization section based on a correlation between the error information and the direction of variation of the value of the first signal.

Automatic delay equalizer and automatic delay equalization method as well as automatic delay and amplitude equalizer and automatic delay and amplitude equalization method

A distortion compensating device provided in a receiver for compensating distortion which is added to a signal in a transmission path. The signal is generated in a multi-level modulator of a transmitter of which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram. The device includes discrimination circuits for discriminating a received signal according to threshold lines partitioning the signal space diagram into discrimination areas, the threshold lines being defined so that the discrimination areas on an outer side of the signal space diagram having each an area greater than an area of each of the discrimination areas on an inner side of the signal space diagram and a selection circuit for selecting one of a plurality of threshold line patterns based on a level of the received signal which is discriminated according to a selected threshold line pattern.

The invention provides an automatic amplitude equalizer for compensating an amplitude characteristic of an input signal, wherein a control signal for equalizing an inclination amplitude distortion of an input signal is detected making use of a pair of digital demodulated signals to compensate for the amplitude characteristic of the input signal with a high degree of accuracy and which can be constructed with a reduced circuit scale and at a reduce cost. The automatic amplitude equalizer includes a first-order inclination amplitude equalization section for compensating for an amplitude characteristic of an input signal in accordance with a first-order inclination amplitude characteristic, and a control section for discriminating a direction of variation of a value of a first one of a pair of digital demodulated signals originating from the input signal, detecting error information from the other, second one of the digital demodulated signals which is orthogonal to the first signal, and outputting a control signal for the first-order inclination amplitude equalization section based on a correlation between the error information and the direction of variation of the value of the first signal.

Automatic amplitude equalizer

Cross polarization interference canceler and cross polarization

In the case where a received multi-level orthogonal amplitude signal is not synchronized with a local carrier frequency signal, a digital multiplexing radio receiver recognizes that an adaptively-equalized data exist in a specified area on the phase plane of Ich and Qch orthogonal coordinates. The receiver controls an operation of amplifying Ich and Qch demodulated signals to a fixed level, based on the data of which exist in the specified area. Similarly, the receiver controls a phase of the local carrier frequency signal based on the data of existing in the specified area, and controls tap coefficients of an adaptive transversal filter which equalizes the received multi-level orthogonal amplitude signal. In the specified area, a distance between signal points of multi-level orthogonal amplitude signal is large so that influence caused by a phase rotation is small. Accordingly, the digital multiplexing radio receiver can rapidly and stably return to a synchronous mode.

Radio receiver for use in the reception of digital multiplexing signals

A microwave digital communication system PSK-modulates a microwave carrier by using a main signal and, further, frequency-modulates it by using a service channel (SC) signal for monitoring and controlling the system. An intermediate relay station employing a space diversity reception system converts a received microwave into an intermediate frequency (IF) to extract the SC signal, and converts the IF signal into a microwave to transmit, thus performing heterodyne relay. The intermediate relay station generates a phase error signal corresponding to the frequency deviation of the IF received signal, by using the IF received signal and an IF reference signal having a fixed frequency equal to the carrier frequency of the IF received signal, and extracts the phase error signal as an SC signal. The SC signal is inputted as a control signal to a VCO for generating a receiving-side local oscillation signal so that the frequency of that follows the variation of the frequency deviation of the received microwave. Thereby, the IF received signal is phase-locked by the IF reference signal, thus suppressing the frequency modulation component of the IF received signal caused by the SC signal. Because the intermediate relay station causes no increase in the frequency modulation factor while adding an SC signal, this relay station facilitates easily regeneration of the carrier performed by the receiving terminal station.

Intermediate relay station of a digital microwave communication system

A fractionally spaced cross-polarization interference canceller, wherein a compensation signal is generated through an adaptive filter operating in a frequency that is an integer multiple of a transmission data frequency. The cross-polarization interference canceller includes a mechanism for generating an error signal used to control coefficients of the adaptive filter in the integer multiple frequency. The mechanism is realized, for example, by using a waveform generator generating an estimate of a baseband signal in the integer multiple frequency using a plurality of estimates of transmission data and coefficients determined by an impulse response of a transmission path.

Growing community of inventors

Kawasaki, Japan

Kenzo Kobayashi