The
CCTV
Glossary
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I
IDE. Interface Device Electronics.
Software and hardware communication standard for
interconnecting peripheral devices
to a computer.
I/O. Input/Output.
I/P. Input.
A signal applied to a piece of electric apparatus or the terminals on
the
apparatus
to which a signal or power is applied.
I2R.
Formula for power in watts (W), where I is current in amperes (A), R is
resistance in
ohms.
IEC. International
Electrotechnical Commission (also CEI).
Imaging device. A
vacuum tube or solid state-device in which the vacuum tube light
sensitive
face plate or solid-state light
sensitive array provides an electronic signal
from which an
image can be created.
Impedance. A property
of all metallic and electrical conductors that describes the total
opposition to current flow in an
electrical circuit. Resistance, inductance, capacitance
and
conductance have various influences
on the impedance, depending on frequency,
dielectric
material around conductors, physical
relationship between
conductors and external factors.
Impedance is often referred to
with the letter Z. It is
measured in ohms, whose symbol is the
Greek letter omega.
Input. Same as I/P.
Inserter (also alphanumeric
video generator).
A device for providing additional information,
normally superimposed on the picture
being displayed; this can range from
one or two
characters to full-screen alphanumeric
text. Usually, such generators use the incoming
video
signal sync pulses as a reference
point for the text insertion
position, which means if the video
signal is of poor quality, the
text stability will also be
of poor quality.
Interference. Disturbances
of an electrical or electromagnetic nature that introduce
undesirable
responses in other electronic equipment.
Interlaced scanning.
A technique of combining two television fields in order to produce a
full
frame. The two fields are
composed of only odd and only even lines, which
are displayed one
after the other but with the physical
position of all the lines interleaving
each other, hence
interlace. This type of television
picture creation was
proposed in the early days of television to
have a minimum amount of information
yet achieve flickerless
motion.
Interline transfer.
This refers to one of the three principles of charge transferring in CCD
chips. The other two are
frame transfer and frame-interline transfer.
IP. Index of Protection.
A 2, (sometimes 3) digit numbering system that describes the quality
of protection of an
enclosure from outside influences,
such as dust and moisture (the third digit
relates to impact).A
IRE. Institute of
Radio Engineers. Units of measurement dividing the area from the
bottom
of sync to peak white level into
140 equal units. 140 IRE equals 1Vpp. The
range of active
video is 100 IRE.
IR. light.
Infrared light, invisible to the human eye. It usually refers to
wavelengths longer
than 700 nm. Monochrome (B/W)
cameras have extremely high sensitivity in
the near
infrared region (715 to 800nm)
of the light spectrum.
Iris. A means of controlling
the size of a lens aperture and therefore the amount of light
passing through the lens.
ISDN. Integrated Services
Digital Network. The newer generation telephone network, usually
ISDN2e which has 2 x B channels
each of 64 kbps speed of transmission giving a total
of
128kbps (being a digital network,
the signal bandwidth
is not expressed in kHz, but rather with
a transmission speed). This
is much faster than a
normal PSTN telephone line. To use the
ISDN network you
have to talk to your communications
provider, but in general a special
interface unit called a terminal
adaptor is required, modems cannot be used on an ISDN line.
ISIT.
Intensified Silicon Intensified Target. A type of detector tube
for
use in very low light
conditions such as starlight.
ISO. International
Standardization Organization.
ITU. International
Telecommunications Union (also UIT).
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