Nippon Telegraph and Telephone Corporation

Nihon Dengyo Kosaku Co., Ltd.

Tadashi Shirato

Yoshifumi Suzuki

Takashi Okada

Toshiaki Takao

Minoru Furukawa

Hideaki Matsue

Takehiro Murase

Hiroyuki Ohtsuka

A power regeneration device includes an extraction unit and a high frequency-to-DC converter. The extraction unit is provided on a transmission path. The transmission path is provided for transmitting a high-frequency wave from a high-frequency wave source to a high-frequency load. The extraction unit extracts a reflected high-frequency wave generated by reflecting the high-frequency wave from the high-frequency load. The high frequency-to-DC converter converts the reflected high-frequency wave extracted by the extraction unit into DC power.

Power regeneration device, method of regenerating power, power storage system, method of storing power, and high frequency device

A clock timing recovery circuit for recovering the clock timing from a baseband signal obtained by detection of a received signal. The clock timing is rapidly established using a clock signal which has been phase-shifted from the desired clock timing to sample the baseband signal, and by obtaining the optimum phase from the sampled signal obtained as a result. A clock-timing recovery circuit according to this invention does not require oversampling and provides easy optimization of circuit constants.

Clock timing recovery methods and circuits

A modulation and demodulation method for communication between a transmitting side and a receiving side includes a step of at the transmitting side, producing a modulating signal, an amplitude ratio of a current instantaneous amplitude of the modulating signal and an instantaneous amplitude at n symbols previously in time (n is a natural number) of the modulating signal being set to correspond to a code to be transmitted, a step of at the transmitting side, modulating a carrier with a radio frequency or an intermediate frequency by the modulating signal to provide and transmit a modulated signal, a step of at the receiving side, receiving the transmitted modulated signal to provide a received signal, and a step of at the receiving side, deciding the transmitted code from an amplitude ratio of an instantaneous amplitude of a signal point in a signal space and an instantaneous amplitude of the signal point in the signal space n symbols previously in time with respect to the received signal. A first amplitude ratio value equal to or smaller than 1 and a second amplitude ratio value equal to or greater than 1 are prepared. The amplitude ratio is selected one of the first and second amplitude values so as to prevent the modulating signal from converging to zero and from diverging.

Modulation and demodulation method, modulator and demodulator

A digitized quadrature modulator receives an I-channel input digital signal and Q-channel input digital signal, and quadrature modulater the I-channel and Q-channel input digital signals by digital signal processing. The modulator has a digital filter (504) for shaping the spectrum of the I-channel and Q-channel input digital signals to provide I-channel and Q-channel output signals. The output signals have a predetermined phase shift between the I-channel and the Q-channel so as to compensate a phase difference based upon the quadrature modulation by the digital signal processing. Complementers (505a, 505b) for taking the complement of the I-channel and Q-channel output signals to provide I-channel and Q-channel complement signals. A multiplexer (505c) multiplexer the I-channel and Q-channel output signals from the digital filter and the I-channel and Q-channel complement signals from the complementers to provide a quadrature modulated output signal.

Digitized quadrature modulator

In a digital demodulation system (FIGS. 2, 3, 4, 7, 8) in a dual polarization radio system, having a first demodulator (4) and a first A/D converter (14) for a main signal, a second demodulator (5) and a second A/D converter (15c) for an interference signal (cross polarization signal), a transversal filter (18) for providing a compensation signal for cancelling an interference component in the main signal depending upon the demodulated interference component; the second A/D converter (15c) for providing the interference component in digital form is operated with a clock signal (102) regenerated in the main signal branch (4, 14) so that system operates correctly even when the main signal and cross polarization signal are in an asynchronous condition. The A/D converter (14, 15c, 105) is provided with an attenuator (104) for compressing amplitude of an input signal to avoid saturation of the circuit (105) in case of fading and/or distortion, and a ROM table (107) for correcting digitalized output after equalization and/or cancellation. Tap coefficients of the transversal filter (18) are obtained by a control (19) through a ZF method when inter-symbol interference is small, and a MLE method when inter-symbol interference is large. Further, an integration constant for the coefficients is adaptive depending upon inter-symbol interference.

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Tokyo, Japan

Tadashi Shirato