A radio receiver uses the same tuner for receiving a selected digital
television (DTV) signal, irrespective of whether it is a
quadrature-amplitude-modulation (QAM) or a vestigial sideband (VSB)
signal. The tuner supplies a final IF signal in a 6-MHz-wide frequency
band, the lowest frequency of which is not appreciably more than 2.69 MHz.
The final IF signal is digitized at a rate that is a multiple of both the
symbol frequencies of the QAM and VSB signals, for synchrodyning to
baseband, with the 2.69 MHz difference between the carrier frequencies of
QAM and VSB signals being taken into account in the digital synchrodyning
circuitry. The carrier frequencies of the QAM and VSB final IF signals are
regulated to be submultiples of the multiple of both the symbol
frequencies of the QAM and VSB signals by applying automatic frequency and
phase control signals developed in the digital circuitry to a local
oscillator of the tuner.