Combo tuners

This is similar to a hybrid
tuner, except there are two
separate tuners on the card.
One can watch analog while
recording digital, or vice
versa. The card operates as
an analog tuner and a digital
tuner simultaneously. The
advantages over two
separate cards are cost and
utilization of expansion slots
in the computer. As many
regions around the world
convert from analog to
digital broadcasts, these
tuners are gaining
popularity.
Like the analog cards, the
Hybrid and Combo tuners can
have specialized chips on the
tuner card to perform the
encoding, or leave this task
to the CPU. The tuner cards
with this 'hardware
encoding' are generally
thought of as being higher
quality.[citation needed]
Small USB tuner sticks have
become more popular in
2006 and 2007 and are
expected to increase in
popularity. These small
tuners generally do not have
hardware encoding due to
size and heat constraints.
While most TV tuners are
limited to the radio
frequencies and video
formats used in the country
of sale, many TV tuners used
in computers use DSP, so a
firmware upgrade is often all
that's necessary to change
the supported video format.
Many newer TV tuners have
flash memory big enough to
hold the firmware sets for
decoding several different
video formats, making it
possible to use the tuner in
many countries without
having to flash the firmware.
However, while it is
generally possible to flash a
card from one analog format
to another due to the
similarities, it is generally not
possible to flash a card from
one digital format to another
due to differences in decode
logic necessary.
Many TV tuners can function
as FM radios; this is because
there are similarities
between broadcast
television and FM radio. The
FM radio spectrum is close to
(or even inside) that used by
VHF terrestrial TV broadcasts.
And many broadcast
television systems around
the world use FM audio. So
listening to an FM radio
station is simply a case of
configuring existing
hardware.