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Hitachi-kokusai Electric Inc.

Kunihiko Kondo

Yoshiro Kokuryo

Nobuo Tsukamoto

Nobuo Hirose

Tetsuomi Ikeda

Hiroyuki Ando

Kenji Terada

Atsushi Mizuno

A demodulation method, and apparatus, for reproducing data from a received signal. The demodulation method includes the steps of: receiving a signal including a series of frames each containing a training signal for automatic equalization processing and a data signal; controlling an amplitude of the received signal by AGC processing so as to make the amplitude a predetermined level; conducting demodulation processing on the signal subjected to the AGC processing; periodically conducting automatic equalization processing so as to adapt the modulated signal to characteristics of the signal transmission path based on each training signal of the frame; and setting values of a time constant of the AGC processing and an update repetition period of the automatic equalization processing so as to satisfy a predetermined relation.

Signal demodulation method and apparatus for reproducing data from received signal

An encoder and a decoder each having an error correcting operation, and a data transmission apparatus using them for data transmission in a multilevel modulation system. In transmission data is converted into parallel data. One bit thereof is inputted to a convolutional encoder to output two bits. Two bit data and another signal of the parallel data not inputted to the convolutional encoder are respectively separated into real part and imaginary part to independently decide signal points for the parallel data. In reception an area is similarly decided independently for real and imaginary parts and metric is assigned for the data. Real and imaginary parts are combined with each other for Viterbi decoding. Result thereof is fed to a convolutional encoder similar in constitution to that on transmission side. Using convolutional encoding output and decided area, transmission data is decoded.

Coder with error correction, decoder with error correction and data transmission apparatus using the coder and decoder

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Kodaira, Japan

Kunihiko Kondo