Fujitsu Corporation

Yukio Takeda

Takaharu Nakamura

Hiroshi Nakamura

Takeshi Takano

Eisuke Fukuda

Yasuyuki Oishi

Yoji Ohashi

Yoshiaki Kaneko

Susumu Sasaki

Masafumi Shigaki

Takenori Ohshima

Kazumi Kasai

Sadao Takenaka

Yoshimasa Daido

Yoshihito Aono

Naoto Tanabe

Yasunobu Watanabe

Akihiko Kimura

A device includes a dielectric, wherein a front and a back of the dielectric for reflecting and transmitting an electromagnetic wave are defined by a first surface and a second surface, the first or second surface forming a half mirror, the first surface has a height that changes in spiral as leaving from the second surface, and the second surface has a height that changes in spiral as leaving from the first surface.

Device to reflect and transmit electromagnetic wave and antenna device

A digital two-way radio communication system including first and second radio stations. Each radio station includes an antenna, a data transmission unit, a data reception unit, and a switching circuit. Both radio stations are radio-connected by a single frequency. When a first data transmission unit transmits data to the second radio station, a first switching circuit in the first radio station forms a transmission path between the first data transmission unit and a first antenna, and a second switching circuit in the second radio station forms a reception path between a second antenna and a second data reception unit in the second radio station, or vice versa.

Digital two-way radio-communication system using single frequency

An FSK demodulation circuit which receives as input an FSK modulated reception signal, obtains two quadrature pulse trains, i.e., a first pulse train and a second pulse train, from a phase detection circuit, is provided with at least two sampling means which use the edge of one of the pulse trains and sample the logic of the other pulse train, produces two or more sample outputs at different timings, and determines the logic of the reproduced data from a combination of the logics '1' and '0' of the sample outputs.

FSK demodulation circuit

A radio communication system using a QAM system. In the transmission system, the data of each channel to be transmitted is divided into data groups having frame slots. When the polarity of the mean value of a data summed in a present data group is the same as the polarity of the mean value of the deviation of all data group coming before, all data in the present data group is inverted, a direct current component and a lower frequency component near the direct current component are suppressed, and carrier waves are injected after encoding. In the receiving system, a decoder decodes a received signal to obtain the original data before the encoding by the transmission system.

Radio communication system

A receiver unit in a radio communication system in which a transmitter unit outputs transmission data, modulated in accordance with a multilevel QAM method and containing a leakage carrier by addition of a DC offset signal to either one of the quadrature components forming the transmission data, to the receiver unit through a transmission line, including: means for receiving the transmission data; means for branching a signal received at the transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of .pi./2 radian; first channel means for demodulating the first branched signal component and including a first synchronous detection circuit and a first discriminator; second channel means for demodulating the second branched signal component and including a second synchronous detection circuit and a second discriminator; and means for recovering the carrier including a control circuit, for cancelling a noise component contained in the output signal from either one of the first and second synchronous detection circuits and for providing only a DC component representing a phase difference between a leakage carrier and a reference carrier, and a phase-locked loop (PLL) circuit, for controlling the phase difference to zero and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of .pi./2 radian, to the first and second synchronous detection circuits.

Receiver unit in radio communication system

A feedback amplifier circuit includes an inversion circuit, a level shift circuit, and a feedback resistive element. The inversion circuit includes an input active element and a load element connected in cascade with respect to a voltage source. The level shift circuit includes a field effect transistor having a gate connected to the output of the inversion circuit, a diode or diodes, a constant current active load connected in cascade with respect to the voltage source, and the feedback resistive element is connected between the output of the level shift circuit and the input of the inversion circuit.

Feedback amplifier

A coordinate reading apparatus for reading positions on a tablet, having magnetic-field generating coils, with a magnetic-field detector. The magnetic-field detector produces an analog electric signal corresponding to a desired position to be read on the tablet in response to the magnetic fields induced by the magnetic-field generating coils. The analog electric signal generated by the detector is composed of both a fundamental wave component signal and an n-th order harmonic wave component signal (n being an integer equal to or larger than 2). A processing unit for receiving the analog electric signal from the magnetic-field detector and produces coordinate data corresponding to the desired position to beread on the tablet by analyzing a first rotating magnetic-field vector induced by the fundamental wave component signal and a second rotating magnetic-field vector induced by the n-th order harmonic wave component signal. The phase component of the fundamental wave component signal and the phase component of the n-th harmonic wave component signal are processed so that the coordinate data can be read by the processing unit.

Growing community of inventors

Zama, Japan

Yukio Takeda