Fujitsu Corporation

Yasuhiro Shibuya

Hiroyuki Kiyanagi

Toshiaki Suzuki

Koji Hirai

Takanori Iwamatsu

Hiroshi Suzuki

Manabu Miyamoto

Hideki Sonobe

Hiroyuki Miura

Yasuo Iwahashi

Masayuki Watabe

Masanori Iwatsuki

Shouichi Sato

Masayuki Oonuki

Kouichi Hayasaka

A wireless communication device performing wireless communication by switching between transmission timing and reception timing in time division, controls to supply a heater or a fan with power supplied from a power supply unit in the reception timing period, and controls to suspend supplying the heater or the fan with the power supplied from the power supply unit in the transmission timing period, in case that a temperature detected by a temperature detector is outside a specified temperature range while a time-division switchover between the transmission timing and the reception timing is performed.

Wireless communication device

A wireless communication apparatus according to the present invention is composed of a first section for carrying out wireless communication with a multichannel signal and a second section having a plurality of channel units each process a predetermined frequency signal as a channel signal. The wireless communication apparatus is arranged to have a plurality of variable attenuators each provided for corresponding one of the channel signals received from each channel unit of the second section, a combiner for combining outputs from the respective variable attenuators together and outputting the resultant combined signal to the first section, and a control unit for controlling the degree of attenuation of the individual variable attenuators according to the variation of the number of the channel signals. According to the arrangement, the wireless communication apparatus can not only communicate with an opponent station by transmitting a multichannel signal but also effectively suppress negative influence on existing channel even if a new channel unit is additionally provided.

Wireless communication apparatus

A communication device includes a number of transmitter/receiver/modem blocks installed in vertical positions. Each of the transmitter/receiver/modem blocks includes a supporting board having a front surface and a back surface, the supporting board including a plurality of fins on the front surface and a plurality of forced air-cooling fans on the supporting board. A front cover encloses the front surface of the supporting board, the front cover and the fins forming a plurality of ducts, the front cover and the front surface forming an internal opening under the fins. A back cover encloses the back surface of the supporting board. First heat-radiating circuit modules are provided at positions adjacent to the fins on the front surface. A second heat-radiating circuit module is provided within the opening. When the forced air-cooling fans operate, the fans produce a flow of air along the plurality of ducts to cool the first heat-radiating circuit modules, and the fans producing a flow of air within the opening to cool the second heat-radiating circuit board.

Communication device

The present invention is directed to a multiplex radio transmission/receiving system. The system includes a plurality of transmission sections provided so as to correspond to a plurality of channels, and a plurality of receiving sections provided so as to correspond to the plurality of channels. Each transmission section includes a modulation section, a first frequency conversion section, a first band-pass filter, a second frequency conversion section, and a second band-pass filter. Each receiving section includes a third band-pass filter, a third frequency conversion section, a fourth band-pass filter, a fourth frequency conversion section, and a demodulation section. By selection of an optimum value for a second intermediate frequency of a transmitter and for a third intermediate frequency of a receiver, a group of transmission radio frequencies (RF) signals and a group of local frequency signals are allocated without overlap. As a result, there can be prepared one type of band-pass filter which has broad band-pass characteristics and which is common among the transmission and receiving sections disposed within the multiplex radio transceiver or among repeaters, thus allowing use of common members.

Multiplex radio transmitter and multiplex radio transmission method, multiplex radio receiver and multiplex radio receiving method, and multiplex radio transceiver and multiplex transmission/receiving system

A space diversity receiver apparatus receives signals by two spatially separated antennas, controls the phase of the signal received by one of the antennas by a phase control circuit, combines the phase-controlled signal and the signal received by the other antenna by a combiner and outputs the combined signal. A digital detector digitally detects the center frequency level and the levels on high- and low-frequency sides of the center frequency of the combined signal. Phase is controlled in such a manner that the center frequency level will coincide with a set level and a deviation between the levels on the high- and low-frequency sides of the center frequency will become zero.

Space diversity receiving apparatus

Simple and low-cost linearizing circuit for compensating for amplitude and phase distortion produced in a power amplification stage of a radio transmitter apparatus that is required to have a high linearity. Amplitude distortion compensation means, disposed in an intermediate frequency amplifier, has a field-effect transistor whose gate bias voltage is set near to its pinchoff voltage and compensates for amplitude distortion produced in a radio frequency amplifier. On the other hand, phase distortion compensation means having a varactor diode and a branch-line hybrid is disposed in the radio frequency amplifier so as to compensate for phase distortion produced in the radio frequency amplifier. The phase distortion compensation means can be disposed in a local frequency oscillation circuit, alternatively.

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Sendai, Japan

Yasuhiro Shibuya