Pulse or digital communications – Receivers – Angle modulation
Reexamination Certificate
2004-08-02
2008-07-29
Phu, Phuong (Department: 2611)
Pulse or digital communications
Receivers
Angle modulation
C375S327000, C375S324000, C375S325000, C375S376000, C348S726000
Reexamination Certificate
active
07406137
ABSTRACT:
A carrier recovery system includes an in-phase mixer for mixing an incoming signal with an in-phase reference signal to produce an in-phase baseband signal; a quadrature-phase mixer for mixing the incoming signal with a quadrature-phase reference signal to produce a quadrature-phase baseband signal; a DC detector for measuring a DC offset of the quadrature-phase baseband signal; and a frequency synthesizer for generating the in-phase reference signal and the quadrature-phase reference signal according to the DC offset measured by the DC detector. The quadrature-phase reference signal is the in-phase reference signal phase-delayed by ninety degrees. The DC offset of the quadrature-phase baseband signal is caused by a pilot tone of the VSB signal for a selected carrier in an Advanced Television Systems Committee (ATSC) digital television (DTV) receiver. By minimizing the DC offset, the carrier recover system locks the quadrature-phase reference signal and the in-phase reference signal to the selected channel.
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Bretl.W. Sgrignoli.G. Snopko.P., “VSB modem subsystem design for Grand Alliance digital television receivers”, Aug. 1995, p. 773-786, IEEE Transactions on Consumer Electronics.
Huang Cheng-Yi
Peng Bao-Chi
Wang Wei-Ting
Hsu Winston
Phu Phuong
Realtek Semiconductor Corp.
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