GRASS VALLEY Ignite SDC Series Instruction Manual page 114

Glossary
S/N (Signal to Noise) Ratio
The amount of desired signal as compared to
undesired signal. A way of measuring how
good a picture or a sound will be. The higher
the ratio between the desired type of signal
and the unwanted noise, the better the re-
sults.
Source
1) An external device providing video. A
source may provide only one video signal, or
it may provide two signals (key fill and key
cut).
2) The video signal(s) from a source, along
with the source definition information asso-
ciated with that source. See Source Defini-
tion.
Subnet Mask
In the Internet Protocol (IP), a subnet (or sub-
network) is a division of a classful network.
Subnetting allows a single large network to
be broken down into what appear (logically)
to be several smaller ones. A network mask,
also known as a subnet mask, netmask or
address mask, is a bitmask used to tell how
many bits in an octet(s) identify the subnet-
work, and how many bits provide room for
host addresses. They are typically used to de-
termine whether to send a packet to the
MAC address of the default gateway (for
packets with destinations outside the subnet)
or of the actual machine (for inside the sub-
net).
Switcher
A device that accepts inputs from a variety of
video sources and allows the operator to se-
lect a particular source to be sent to the
switcher's output(s). Also does transitions
between sources and special effects (video
mixing, wiping, keying, and such).
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Sync
(1) General term for a synchronizing signal
or signal component. Digital systems gener-
ally employ an analog external timing refer-
ence signal (such as color black or tri-level
sync) to synchronize different pieces of
equipment. Within the digital signal itself,
however, synchronizing information is car-
ried by special digital codes inserted at the
beginning and end of each active line.
(2) In analog television systems, sync is the
portion of the video signal which occurs dur-
ing blanking and is used to synchronize the
operation of cameras, monitors, and other
equipment. Horizontal sync occurs within
the blanking period in each horizontal scan-
ning line, and vertical sync occurs within the
vertical blanking period. A color black signal
is often used for synchronizing different
pieces of analog equipment.
T
Tally
A lighted indication that the associated vid-
eo source is in use. Tally lights may be in
front of a camera to show that it is the camera
being used at that moment, or they may be
used to light up the pushbuttons of video
switchers.
Terminate, Termination
To complete a circuit by connecting a resis-
tive load to it.
TFT
Thin-film Transistor. Often called "active
matrix" display, this is the brightest, most
viewable kind of LCD flat-panel display. It is
also more expensive than "passive matrix"
screens. In a TFT display, each pixel is active-
ly controlled by one or more transistors.
Ignite Glossary