| 01.AGC |
|
| Automatic gain control.
A section in an electronic circuit that has feedback
and regulates a certain voltage level to fall within
predetermined margins |
| |
| 02.ALC |
|
| Automatic light control
A part of the electronics of an automatic iris lens
that has a function similar to backlight compensation
in photography. |
| |
| 03.Aperture |
|
| The opening of a lens that
controls the amount of light reaching the surface of
the pickup device. The size of the aperture is controlled
by the iris adjustment. By increasing the F- stop number(
F / 1.4, F / 1.8, F / 2.8, etc.) less light is permitted
to the pickup device. |
| |
| 04.Auto
iris ( AI ) |
|
| An automatic method of
varying the size of a lens aperture in response to changes
in scene illumination. |
| |
| 05.Back-focus |
|
| A procedure of adjusting
the physical position of the CCD - chip / lens to achieve
the correct focus for all focal length settings (especially
critical with zoom lenses). |
| |
| 06.BNC |
|
| BNC stands for Bay9onet
- Neil - Councilman connector, and it is the most popular
connector in CCTV and broadcast TV for transmitting
a basic bandwidth video signal over a coaxial cable. |
| |
| 07.Brightness |
|
| In
NTSC and PAL video signals, the brightness information
at any particular instant in a picture is conveyed by
the corresponding instantaneous DC level of active video.
Brightness control is an adjustment of setup ( black
level, black reference ). |
| |
| 08.CCD |
|
| Charge-coupled device.
The new age imaging device, replacing the old tubes.
When first invented in the 1970s, it was initially intended
to be used as a memory device. Most often used in cameras,
but also in telexing, fax machines, scanners, etc. |
| |
| 09.CCIR |
|
| Committee Consultative
International des Radio communique or, in English, Consultative
Committee for International Radio, which is the European
standardization body that has set the standards for
television in Europe. It was initially monochrome; therefore,
today the term CCIR is usually used to refer to monochrome
cameras that are used in PAL countries. |
| |
| 10.CCTV |
|
| Closed circuit television
A television system intended for only a limited number
of viewers, as opposed to broadcast TV. |
| |
| 11.C-mount |
|
| The first standard for
CCTV lens screw mounting. It is defined with the thread
of 1" ( 2.54mm ) in diameter and 32 threads/inch, and
the back flange-to-CCD distance of 17.526mm ( 0.69"
). The C-mount description applies to both lenses and
cameras. C-mount lenses can be put on both C-mount and
CS-mount cameras, only in the latter case an adaptor
is required. |
| |
| 12.Coaxial
cable |
|
| The most common type of
cable used for copper transmission of video signals.
It has a coaxial cross-section, where the center core
is the signal conductor, while the outer shield protects
it from external electromagnetic interference. |
| |
| 13.CS-Mount |
|
| A newer standard for lens
mounting. It uses the same physical thread as the lenses
made smaller, more compact and less expensive.CS-mount
lenses can only be used on CS-mount cameras. |
| |
| 14.dB |
|
| Decibel A logarithmic ratio
of two signals or values, usually refers to power, but
also voltage and current. When power is calculated the
logarithm is multiplied by 10, while for current and
voltage by 20. |
| |
| 15.DSP |
|
| Digital signal processing.
It usually refers to the electronic circuit section
of a device capable of processing digital signals. |
| |
| 16.EIA |
|
| Electronics Industry Association,
which has recommended the television standard used in
the U. S¡FCanada and Japan, based on 525 lines
interlaced scanning. Formerly known as RMA or RETMA. |
| |
| 17.F-number |
|
| In lenses with adjustable
irises, the maximum iris opening is expressed as a ratio
( focal length of the lens )/( maximum diameter of aperture
). This maximum iris will be engraved on the front ring
of the lens. |
| |
| 18.Focal
length |
|
| The distance between the
optical center of a lens and the principal convergent
focus point. |
| |
| 19.Gain |
|
| Any increase or decrease
in strength of an electrical signal. Gain is measured
in terms of decibels or number of tines of magnification. |
| |
| 20.Gamma |
|
| A correction of the linear
response of a camera in order to compensate for the
monitor phosphor screen nonlinear response. It is measured
with the exponential value of the curve describing the
non-linearity. A typical monochrome monitor's gamma
is 2.2, and a camera needs to be set to the inverse
value of 2.2( which is 0.45 )for the overall system
to respond linearly ( I. e; unity ). |
| |
| 21.Gen-lock |
|
| way of locking the video
signal of a camera to an external generator of synchronization
pulses. |
| |
| 22.Horizontal
resolution |
|
| Chrominance and luminance
resolution (detail) expressed horizontally across a
picture tube. This is usually expressed as a number
of black to white transitions or lines that can be differentiated.
Limited by the bandwidth of the video signal or equipment. |
| |
| 23.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 infrared region of the light
spectrum. |
| |
| 24.Iris |
|
| A means of controlling
the size of a lens aperture and therefore the amount
of light passing through the lens. |
| |
| 25.Lens |
|
| An optical device for focusing
a desired scene onto the imaging device in a CCTV camera. |
| |
| 26.Line-locked |
|
| In CCTV, this usually refers
to multiple cameras being powered by a common alternative
current (AC) source (either 24V AC, 110V AC or 240V
AC) and consequently have field frequencies locked to
the same AC source frequency (50 Hz in CCIR systems
and 60Hz in EIA systems). |
| |
| 27.Lox
[Ix ] |
|
| Light unit for measuring
illumination. It is defined as the illumination of a
surface when luminous flux of 1 lumen falls on an area
of 1 m. It is also known as lumen per square meter or
meter-candelas. |
| |
| 28.NTSC |
|
| National Television System
Committee. American committee that set the standards
for color television as used today in the U.S., Canada,
Japan and parts of South America. NTSC television uses
a 3.57945 MHz sub-carrier whose phase varies with the
instantaneous hue of the televised color and whose amplitude
varies with the instantaneous saturation of the color.
NTSC employs 525 lines per frame and 59.94 fields per
second. |
| |
| 29.Output
impedance |
|
| The impedance a device
presents to its load. The impedance measured at the
output terminals of a transducer with the load disconnected
and all impressed driving forces taken as zero. |
| |
| 30.PAL |
|
| Phase alternating line.
Describes the color phase change in a PAL color signal.
PAL is a European color TV system featuring 625 lines
per frame, 50 fields per second and a 4.43361875-MHz
sub-carrier. Used mainly in Europe, China, Malaysia,
Australia, New Zealand, the Middle East and parts of
Africa. PAL-M is a Brazilian color TV system with phase
alternation by line, but using 525 lines per frame,
60 fields per second and a 3.57561149-MHz sub-carrier. |
| |
| 31.Pan
and tilt head (P/T head) |
|
| A motorized unit permitting
vertical and horizontal positioning of a camera and
lens combination. Usually 24V AC motors are used in
such P/T heads, but also 110V AC, i.e., 240V AC units
can be ordered. |
| |
| 32.Pan
unit |
|
| A motorized unit permitting
horizontal positioning of a camera. |
| |
| 33.Peak-to-peak
(pp) |
|
| The amplitude (voltage)
difference between the most positive and the most negative
excursions (peaks) of an electrical signal. |
| 34.Pixel |
|
| Derived from picture element.
Usually refers to the CCD chip unit picture cell. It
consists of a photo sensor plus its associated control
gates. |
| |
| 35.Protocol |
|
| A specific set of rules,
procedures or conventions relating to format and timing
of data transmission between two devices. A standard
procedure that two data devices must accept and use
to be able to understand each other. The protocols for
data communications cover such things as framing, error
handing, and transparency and line control. |
| |
| 36.PTZ
camera |
|
| Pan, tilt and zoom camera. |
| |
| 37.PTZ
site driver (or receiver or decoder) |
|
| An electronic device, usually
a part of a video matrix switcher, which receives digital,
encoded control signals in order to operate pan, tilt,
zoom and focus functions. |
| |
| 38.Resolution |
|
| A measure of the ability
of a camera or television system to reproduce detail.
The number of picture elements that can be reproduced
with good definition. |
| |
| 39.Remote
control |
|
| A transmitting and receiving
of signals for controlling remote devices such as pan
and tilt units, lens functions, wash and wipe control
and similar. |
| |
| 40.RG-58 |
|
| A coaxial cable designed
with 50-ø[ impedance; therefore, not suitable
for CCTV. Very similar to RG-59, only slightly thinner. |
| |
| 41.RG-59 |
|
| A type of coaxial cable
that is most common in use in small to medium-size CCTV
systems. It is designed with an impedance of 75-ø[.
It has an outer diameter of around 6 mm and it is a
good compromise between maximum distances achievable
(up to 300 m for monochrome signal and 250 m for color)
and good transmission. |
| |
| 42.RS-232 |
|
| A format of digital communication
where only two wires are requited. It is also known
as a serial data communication. The RS-232 standard
defines a scheme for asynchronous communications, but
it does not define how the data should be represented
by the bits, i.e., it does not define the overall message
format and protocol. It is very often used in CCTV communications
between keyboards and matrix switchers or between matrix
switchers and PTZ site drivers. The advantage of RS-232
over others is its simplicity and use of only two wires. |
| |
| 43.RS-485 |
|
| This is an
advanced format of digital communications compared to
RS-422. The major improvement is in the number of receivers
that can be driven with this format, and this is up
to 32. |
| |
| 44.Signal-to-Noise
ratio (S/N) |
|
| An S/N ratio can be given
for the luminance signal, chrominance signal and audio
signal. The S/N ratio is the ratio of noise to actual
total signal, and it shows how much higher the signal
level is than the level of noise. It is expressed in
decibels (dB), and the bigger the value is, the crisper
and clearer the picture and sound will be during playback.
An S/N ratio is calculated with the logarithm of the
normal signal and the noise RMS value. |
| |
| 45.Twisted-pair |
|
| A cable composed of two
small-insulated conductors twisted together. Since both
wires have nearly equal exposure to any interference,
the differential noise is slight. |
| |
| 46.White
balance |
|
| An electronic process used
in video cameras to retain true colors. It is performed
electronically on the basis of a white object in the
picture. |
| |
| 47.Y/C |
|
| A video format found in
Super-VHS video recorders. Luminance is marked with
Y and is produced separate to the C, which stands for
chrominance. Thus, an S-VHS output Y/C requires two
coaxial cables for a perfect output. |
| |
| 48.Zoom
lens |
|
|
A camera lens that
can vary the focal length while keeping the object
in focus, giving an impression of coming closer to
or going away from an object. It is usually controlled
by a keyboard with buttons that are marked zoom-in
and zoom-out.
|
| |
