Fujitsu Corporation

Yoichi Endo

Yoshiaki Kumagai

Eiji Itaya

Hideyuki Kannari

Yutaka Oda

Naoki Ninagawa

In a wireless transmitting/receiving device of TDD system etc., a transmission signal is detected on the transmitting side in a specified transmission period, a signal reflected from an antenna through a circulator is detected on the receiving side in the transmission period and a reception signal is detected on the receiving side in a specified reception period. In this case, in a part of the transmission period a transmission signal having been detected on the transmitting side is selected while in the remaining part of the transmission period a reflection signal having been detected on the receiving side through a circulator from an antenna is selected, and in the reception period a reception signal having been detected on the receiving side through the circulator from the antenna is selected and outputted.

Wireless transmitting/receiving device

A shared bus system includes a bus, a first circuit which accesses the bus, a second circuit which shares the bus with the first circuit, and accesses the bus, a counter circuit which is provided in the second circuit, and performs a counting operation each time the second circuit accesses the bus, and an arbiter circuit which arbitrates requests for a right to use the bus between the first circuit and the second circuit, wherein the second circuit releases the right to use the bus in response to detection of a predetermined number of counting operations performed by the counter circuit after acquiring the right to use the bus from the arbiter circuit.

Avoidance of extended bus occupancy through simple control operation

An automatic frequency control (AFC) circuit receives input signals and generates converted signals by mixing the input signals with a local oscillation signal. An extraction circuit extracts a pilot signal, if present, from the input signals and provides the pilot signal to a switch. A frequency divider divides a frequency of the local oscillation signal output from a voltage control oscillator, and provides the frequency-divided local oscillation signal to the switch. The output of the switch is compared with a reference frequency in a phase comparator which generates a comparison result which controls the voltage controlled oscillator. If the pilot signal is not present, the switch selects the frequency-divided oscillation signal, to construct a phase-locked loop to stabilize the frequency of the local oscillation signal. Alternatively, an AFC circuit includes a frequency divider for selectively dividing a frequency of a pilot signal included in the converted signal. Various frequencies of the pilot signal can be received by altering a division number in the frequency divider.

Automatic frequency control circuit selectively using frequency-divided

An automatic frequency control circuit which can set a local oscillator synthesizer to a small frequency division number, without requesting the exact required frequency. The automatic frequency control circuit includes a voltage source for producing a desired voltage to offset the oscillation frequency of a voltage controlled oscillator, and an adder for adding the output from the voltage source to a frequency control signal of the voltage controlled oscillator. The automatic frequency control circuit is applicable to the receiver for a satellite telecommunications apparatus.

AFC circuit having local oscillator phase locked loop

A signal transmission device having ALC function includes a detection circuit for output level detection when used in a multi-carrier :system where the number of carriers changes. The signal transmission device further has a variable attenuator for controlling a level of a transmission signal. A transmission circuit is coupled to the output of the variable attenuator for modulating a local oscillation signal with the output of the variable attenuator and for generating a modulated output signal. The detection circuit is provided with the modulated output signal for generating a detection voltage. The detection circuit includes a diode having a square-law characteristic region. A reference voltage generating circuit receives an information signal indicative of the number of carriers for generating a reference voltage corresponding to the number of carriers. A first control circuit is provided, receiving the detecting voltage and the reference voltage, for generating and supplying, to the variable attenuator, a first control signal of a difference between the detection voltage and the reference voltage. A second control circuit is supplied with the information signal indicative of the number of carriers, for generating and supplying, to the detection circuit, a second control signal corresponding to the number of carriers, whereby the square-law characteristic region of the diode in the detection circuit is shifted responding to the second control signal.

Signal transmission device having an automatic transmission level

An automatic transmission level control device used in a multi-carrier communication system includes a gain controller for controlling a level of a transmission signal, a transmitter for amplifying the transmission signal, and a hybrid circuit for extracting a part of power of the transmission signal from the transmitter. A level control circuit adjusts a gain of the gain controller on the basis of a magnitude of the transmission signal and data indicating a number of carriers included in the transmission signal. A carrier detection unit filters the transmission signal and generates the data indicating the number of carriers included therein.

Automatic transmission level control device

A signal generator having a switching function includes a first oscillation circuit, a second oscillation circuit, a frequency-division circuit and a combination circuit. The first oscillation circuit outputs a first frequency signal having a first frequency and a reset signal synchronized with the first frequency signal. The second oscillation circuit outputs a second frequency signal having a second frequency which is N times higher than the first frequency. The frequency-division circuit frequency-divides the second frequency signal by N, resets a value for frequency-division based on the reset signal and generates a divided second frequency signal. The combination circuit combines the first frequency signal and the divided second frequency signal and outputs a combined signal.

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Kawasaki, Japan

Yoichi Endo