Multiplex communications – Generalized orthogonal or special mathematical techniques – Quadrature carriers
Patent
1995-05-09
1998-03-24
Safourek, Benedict V.
Multiplex communications
Generalized orthogonal or special mathematical techniques
Quadrature carriers
370210, 370491, 370516, 375261, H04L 2734
Patent
active
057320683
ABSTRACT:
A signal transmitting apparatus using orthogonal frequency division multiplexing includes an inverse fast Fourier transform circuit for converting a digital information signal into a first multi-value QAM modulation signal. A guard interval setting circuit is operative for periodically generating a guard interval signal equal to a time segment of the first multi-value QAM modulation signal, and inserting the guard interval signal into the first multi-value QAM modulation signal to convert the first multi-value QAM modulation signal into a second multi-value QAM modulation signal. A clock signal generating circuit is operative for generating a first clock signal which drives the inverse fast Fourier transform circuit, and generating a second clock signal which drive the guard interval setting circuit. The inverse fast Fourier transform circuit is operative for generating a pilot signal which corresponds to a given-order carrier, and adding the pilot signal to the first multi-value QAM modulation signal. The pilot signal has a predetermined frequency and an angle modulation component which remains constant over a plurality of symbol periods. The pilot signal corresponding to a given integer times its wavelength is present in a guard interval occupied by the guard interval signal in the second multi-value QAM modulation signal. The pilot signal is continuously present over the guard interval and another interval.
REFERENCES:
patent: 5228062 (1993-07-01), Bingham
patent: 5345440 (1994-09-01), Gledhill et al.
patent: 5444697 (1995-08-01), Leung et al.
Sugiyama Kenji
Takahashi Nobuaki
Takahashi Susumu
Safourek Benedict V.
Victor Company of Japan Ltd.
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