Atr Optical & Radio Communications Research Laboratories

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Atr Adaptive Communications Research Laboratories

Atr Optical and Radio Communications Research Labs

Yoshio Karasawa

Isamu Chiba

Ryu Miura

Tetsuya Miyazaki

Minoru Yoshida

Nobuaki Imai

Toyohisa Tanaka

Keizo Inagaki

Kazuhiro Kimura

Toshikazu Gozen

Yu Ji

In an optical amplifier apparatus for amplifying an incident signal light having wavelengths of 1.06 &mgr;m band, a first optical isolator makes an incident signal light pass therethrough in one direction from an input end to an output end. An optical fiber includes a core mainly composed of silica glass and doped with a predetermined rare-earth element and the other elements, and a cladding of silica glass, and transfers in a single mode the signal light output from the first optical isolator. An optical multiplexer multiplexes an excitation light having an excitation wavelength of 0.8 &mgr;m band with the signal light transferred by the optical fiber, by outputting the excitation light to the optical fiber, and further transfers and outputs the signal light having wavelengths of 1.06 &mgr;m band amplified by induced emission in the optical fiber due to the rare-earth element excited by the excitation light. Further, a second optical isolator makes the signal light outputted from the optical multiplexer pass therethrough in one direction from an input end thereof to an output end thereof, and outputs the signal light as an amplified signal light.

1.06 &mgr;m band optical amplifier apparatus utilizing induced emission in optical fiber by excited rare-earth element

Disclosed is an optical control type phased array antenna apparatus having an array antenna of antenna elements. An optical signal processor optically processes input high-frequency signals, and outputs optically processed signals including signal components having phases corresponding to directions in which radio wave signals come and having frequencies equal to those of the input high-frequency signals. Then, each frequency converter mixes a received signal with the optically processed signal in correspondence with the antenna element, and outputs a frequency-converted signal having a frequency of a difference between a frequency of the received signal and a frequency of the optically processed signal. Further, a combiner combines the frequency-converted signals. When reference signals each having a frequency that differs from the frequency of the corresponding radio wave signal by an intermediate frequency are inputted to the optical signal processor as the input high-frequency signals, intermediate frequency signals having the intermediate frequencies and corresponding to the radio wave signals are outputted as received signals from the combiner.

Optical control type phased array antenna apparatus equipped with

A satellite communication system has a double-layered earth orbit satellite constellation with a lower first orbit altitude and a higher second orbit altitude. In the satellite communication system, first and second communication satellites are deployed in respective earth orbits located at the first and second orbit altitudes to each have first and second satellite communication stations, respectively. Small terminals and large terminals are further provided as earth stations on the earth. Each first satellite communication station communicates with the small terminals and communicates with the first satellite communication stations of adjacent first communication satellites within the same earth orbit and the second satellite communication stations, and each second satellite communication station communicates with the large terminals and communicates with the second satellite communication stations of adjacent communication satellites within the same earth orbit, the second satellite communication stations of the second communication satellites of both adjacent earth orbits, and the first satellite communication stations.

Satellite communication system having double-layered earth orbit

In an apparatus and method for controlling an array antenna comprising a plurality of antenna elements arranged so as to be adjacent to each other in a predetermined arrangement configuration, a plurality of received signals received by the antenna elements is transformed into respective pairs of quadrature baseband signals, using a common local oscillation signal, wherein each pair of quadrature baseband signals is orthogonal to each other. Then predetermined first and second data are calculated based on each pair of transformed quadrature baseband signals, and are filtered using a noise suppressing filter. Respective elements of a transformation matrix for in-phase combining are calculated based on the filtered first and second data, and the received signals obtained from the each two antenna elements are put in phase based on the calculated transformation matrix. Thereafter, a plurality of received signals which are put in phase are combined in phase, and an in-phase combined received signal is outputted.

Apparatus and method for controlling array antenna comprising a

In an apparatus for adaptively controlling an array antenna of M antenna elements, a multi-beam forming circuit calculates N beam field strengths in a known manner, and a beam selecting circuit selectively outputs beam field strengths not smaller than a predetermined threshold value by comparing the N beam field strengths with the threshold value. At least two adaptive control processors calculate N weight coefficients corresponding to N beams according to a constant modulus algorithm, respectively multiplies the calculated beam field strengths by the calculated N weight coefficients, and combines in phase respective signals of multiplication results, outputting the combined signal as a reception signal. In an initial state of one adaptive control processor, a weight coefficient thereof corresponding to the maximum beam field strength is set to a predetermined initial value not zero, and weight coefficients corresponding to the other beam field strengths are set to zero. In an initial state of the other adaptive control processor, a weight coefficient of the other adaptive control processor corresponding to at least a beam field strength having the second greater level is set to the initial value, and weight coefficients corresponding to the other beam field strengths is set to zero.

Apparatus and method for adaptively controlling array antenna comprising

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Nara, Japan

Yoshio Karasawa