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.