Multiplex communications – Generalized orthogonal or special mathematical techniques – Quadrature carriers
Patent
1994-11-16
1997-02-11
Hsu, Alpus H.
Multiplex communications
Generalized orthogonal or special mathematical techniques
Quadrature carriers
370517, 375324, 375362, H04L 700
Patent
active
056028350
ABSTRACT:
An OFDM synchronization demodulation circuit includes a recovery circuit, an orthogonal axis demodulation circuit, a first and second delay circuit, a correlation calculation circuit, a guard timing detection circuit, and an OFDM signal demodulation circuit. The receiving circuit receives an orthogonal modulated wave based on an orthogonal frequency division multiplex (OFDM) modulated signal having an available symbol period and a guard period, where the guard period of the orthogonal modulated wave is based on a part of the available symbol period. The orthogonal axes demodulation circuit demodulates an in-phase axis detection signal and an orthogonal axis detection signal for the OFDM modulated wave from the receiving circuit using orthogonal detection. The first delay circuit delays the in-phase axis detection signal by the available symbol period, and the second delay circuit delays the orthogonal axis detection signal by the available symbol period. The correlation calculation circuit calculates coefficients of the correlations of the in-phase axis detection signal and the orthogonal axis detection signal from the orthogonal demodulation circuit with the output of the first or the second delay circuits. The guard timing detection circuit detects a timing of the guard period in the demodulation outputs from the orthogonal demodulation circuit. The OFDM signal demodulation circuit demodulates the OFDM modulated signal by extracting the available symbol period signal only from the demodulated output of the orthogonal demodulation circuit using the timing signal.
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Ishikawa Tatsuya
Seki Takashi
Sugita Yasushi
Hsu Alpus H.
Kabushiki Kaisha Toshiba
Rao Seema S.
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