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. |
