Definitions

AGC. Automatic Gain Control. A term used for both video and sound. AGC increases the gain (amplification) to compensate for a weak signal.
Back light compensation (BLC). A feature on some cameras which brightens the picture to compensate for when your subject is too dim due to the background being too bright.
Board Camera. A small circuitboard with a miniature camera built onto it.
CCD (Charge Coupled Device). Typically provides a higher resolution picture than CMOS, with less picture noise, but need more power to run. CCD cameras can also be more sensitive, so can be used in lower light situations.
CMOS (Complimentary Metal-Oxide Semiconductor). Normally less expensive than CCD and need less power, so much better suited to battery operation. The downside of CMOS is that they typically have more picture noise.
Dome Camera. A miniture camera built inside a small plastic dome-shaped cover. Normally installed on the ceiling.
Nightvision. A camera equipped with infra-red sensing can see in total darkness.
NTSC (National Television Standards Committee). A video standard used in North America and Japan. 30 frames per second, 640x480 picture size. Many people claim the acronym stands for "Never Twice the Same Colour" because of the standard's inherent lack of good colour stability.
PAL (Phase Alternating Line). A video standard used almost everywhere in the world outside of North America and Japan. 25 frames per second, 768 x 576 picture size.
Pinhole Camera. A camera designed to view through a small hole, perhaps just 1mm across.
SECAM. A video standard used mainly in France.
Wired camera. A camera that transmits its video (and auido) signal along a cable. Wired cameras normally give a more stable picture than wireless cameras, and are less prone to interference.
Wireless camera. A camera that transmits its picture wirelessly to a receiver that is plugged into monitoring or recording equipment. Wireless cameras still need a power source, although they can be run off battery power. Wireless cameras can be much more convenient than wired cameras.

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