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98 en | Glossary of CCTV Terms VG4 AutoDome Modular Camera System
F.01U.089.433 | 4.0 | 2008.09 User’s Manual Bosch Security Systems, Inc.
Focal Length The distance from the optical center of the lens to the image of an object located at an infinite
distance from the lens. Long focal lengths give a small field of view (e.g. telephoto effect),
while short focal lengths give a wide angle view.
F-Number The standard measure of the lens aperture, which is the iris diameter, divided by the focal
length of the lens. The lower the maximum aperture (or F-Number), the more light that passes
through the lens.
F-Stop See F-Number.
G
Gateway Address A node on a network that serves as an entrance to another network.
Guard Tour Allows recorded tours with a combined duration of 15 minutes. Recorded tours consist of
control commands and can be played back as needed. All camera position information is
stored for maximum flexibility (including pan, tilt, zoom, etc.).
H
Hybrid Streaming The ability to simultaneously stream IP video across a local or wide area network, and CVBS
video via coaxial or fiber optic cabling.
I
Image Stabilization An algorithm that virtually eliminates camera shake in both the vertical and horizontal axes,
resulting in exceptional image clarity.
Images per Second A measurement of the rate that pictures are displayed to create a video stream. A rate of 25
IPS (PAL) or 30 IPS (NTSC) is generally considered to be full motion video.
Infrared Illumination Electromagnetic radiation (light) with a longer wavelength than is visible to the naked eye. IR
illumination is prominent at dusk and dawn and in incandescent lamps. IR illuminators come
in the form of lamps with the appropriate filters, LEDs, or lasers. CCD sensors are less
sensitive to IR than visible light, but IR can significantly increase the total illumination level,
leading to a much better image at low light levels.
Institute of Radio Engineers
A measurement of video amplitude that divides the area from the bottom of sync to peak
white level into 140 equal units. 140 IRE equals 1V peak to peak. The range of active video is
100 IRE.
Intermodal Dispersion
See Modal Dispersion.
IP 66 The IP code (Ingress Protection) indicates the degree of protection provided by enclosures for
electrical equipment. The first number indicates protection of internal equipment against the
ingress of solid foreign objects. The second number indicates protection of internal
equipment against harmful ingress of water. Higher digits refer to higher levels of protection.
See also NEMA rating.
IP Address The address of a device attached to an IP network. Each device on an IP network must use a
unique address. Every IP data packet contains a source address (sender) and a destination
address (recipient). Each IP address consists of 32-bits that are arranged into four 8-bit
“octets” (x.x.x.x). IP addresses range from 0.0.0.0 to 255.255.255.255.