Fujitsu Corporation

Nippon Telegraph and Telephone Corporation

Yoshihito Aono

Takanori Iwamatsu

Morihiko Minowa

Sadao Takenaka

Hiroshi Nakamura

Yoshimasa Daidoh

Toshio Kawasaki

Nobutsugu Fujino

Kenzo Kobayashi

Yoshimasa Daido

Yukio Takeda

Naoto Tanabe

Toshiyuki Takizawa

Toshiaki Sakane

A cross polarization interference canceler includes a digital conversion circuit for subjecting a demodulated signal of one channel to an analog-to-digital conversion out of two channels which are independently formed using carriers having the same frequency but having planes of polarization which are mutually orthogonal. An interference cancelling circuit cancels interference caused by the other channel out of the two channels, with respect to the demodulated signal which is digitally converted by the digital conversion circuit. An integrator circuit performs an integration process with respect to the demodulated signal which is digitally converted by the digital conversion circuit so as to provide negative feedback to the digital conversion circuit.

Cross polarization interference canceler and cross polarization

A fractionally spaced cross-polarization interference canceller, wherein a compensation signal is generated through an adaptive filter operating in a frequency that is an integer multiple of a transmission data frequency. The cross-polarization interference canceller includes a mechanism for generating an error signal used to control coefficients of the adaptive filter in the integer multiple frequency. The mechanism is realized, for example, by using a waveform generator generating an estimate of a baseband signal in the integer multiple frequency using a plurality of estimates of transmission data and coefficients determined by an impulse response of a transmission path.

Fractionally spaced cross-polarization interference canceller

Digital demodulator apparatus

Decision timing control circuit

A digital communication system using a QAM signal and a honeycomb constellation multilevel signal. The digital communication system includes a modulator having a unit for transforming in-phase and quadrature-phase data arranged in a quadrature lattice constellation into two data arranged in a honeycomb constellation, and a unit for amplitude-modulating the transformed data. A demodulator demodulates a transmitted signal output from the modulator.

Multilevel amplitude modulation and demodulation communication system

Radio data transmission system

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.

Coordinate reading apparatus

Growing community of inventors

Kawasaki, Japan

Yoshihito Aono