Illuminance:
is the amount of luminous flux falling on a surface area and is
measured in lux or foot candle.
Image intensified camera:
is a type of camera coupled with an image intensified tube
which generates additional photons. This tube allows the camera to be
used in low light areas.
Image intensifier:
is a device which intensifies light by using light sensitive
phosphor screens. It is used to improve camera performance under low
light conditions.
Impedance:
is the input and output characteristic of any electrical system
and is measured in ohms. For maximum signal transfer, the input and
output impedance should be the same. CCTV systems have a 75 ohm
impedance.
Incandescent light:
is a type of artificial light source invented by Thomas Eddison
in 1862. It has a good spectral response but low life and efficiency.
Index of refraction:
is a ratio between the angle of incidence to the angle of
refraction of light. It depends upon the density of a medium. A denser
medium will have a higher index of refraction and will also bend the
light more.
Infrared detector:
is a type of alarm which works on the principle of infrared
light to detect movement in a zone
Infrared illuminator:
is a type of light source which emits light in the infrared
frequency range.
Infrared link:
is a type of transmission medium in which video, data or audio
are modulated with infrared light and then transmitted into air to a
receiver in a remote location.
Infrared radiation:
is electromagnetic radiation with a wavelength of more than 750
nanometers. It is not visible to the human eye.
Interference:
is external energy which interferes with an electrical signal
causing picture distortions.
Interlacing:
is the process of combining even and odd fields to form a
frame.
Interline transfer chip:
is a type of chip used in most of the current CCTV cameras as
the charge read out method is more efficient than a frame transfer CCD
chip . Vertical streaking and small pixel size are some of the
shortcomings.
Iris:
is a part of a lens that can be adjusted to vary the amount of
light passing through the lens and falling on the CCD chip.
Iris plug:
is a type of connector which connects the camera to an auto
iris lens to provide power to the iris motor and to send the video
signal which controls the iris opening.
ISDN Integrated Services Digital Network:
is a type of telephone network which accepts digital signals. |