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 electronicsignal 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 onfrequency, dielectric
material around conductors, physical relationshipbetween conductors and external factors.
Impedance is often referred to with the letter Z. Itis 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 rangefrom one or two
characters to full-screen alphanumeric text. Usually, such generators use theincoming video
signal sync pulses as a reference point for the textinsertion position, which means if the video
signal is of poor quality, the text stability will alsobe of poor quality.
Interference. Disturbances of an electrical or electromagnetic nature that introduceundesirable
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 linesinterleaving each other, hence
interlace. This type of television picture creationwas proposed in the early days of television to
have a minimum amount of information yetachieve 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 anenclosure 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 sensitivityin 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 signalbandwidth is not expressed in kHz, but rather with
a transmission speed). This is much fasterthan a normal PSTN telephone line. To use the
ISDN network youhave 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).