| 01.AGC |
|
| Automatic
gain controlĦOA 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 photographyĦO
|
| |
| 03.Aperture |
|
| The
opening of a lens that controls the amount of light reaching the surface
of the pickup deviceĦOThe size of the aperture is controlled by
the iris adjustmentĦOBy increasing the F- stop number( F / 1.4ĦMF
/ 1.8ĦMF / 2.8ĦMetcĦO) less light is permitted to the pickup
deviceĦO |
| |
| 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)ĦO |
| |
| 06.BNC |
|
| BNC
stands for Bay9onet - Neil - Councilman connectorĦMand it is the
most popular connector in CCTV and broadcast TV for transmitting a
basic bandwidth video signal over a coaxial cableĦO |
| |
| 07.Brightness |
|
| In
NTSC and PAL video signalsĦMthe brightness information at any particular
instant in a picture is conveyed by the corresponding instantaneous
DC level of active videoĦOBrightness control is an adjustment of
setup ( black levelĦMblack reference ). |
| |
| 08.CCD |
|
| Charge-coupled
deviceĦOThe new age imaging deviceĦMreplacing the old tubesĦOWhen
first invented in the 1970sĦMit was initially intended to be used
as a memory deviceĦOMost often used in camerasĦMbut also in telexingĦMfax
machinesĦMscannersĦMetcĦO |
| |
| 09.CCIR |
|
| Committee
Consultative International des Radio communique orĦMin EnglishĦMConsultative
Committee for International RadioĦMwhich is the European standardization
body that has set the standards for television in EuropeĦOIt was
initially monochromeĦQthereforeĦMtoday the term CCIR is usually
used to refer to monochrome cameras that are used in PAL countriesĦO |
| |
| 10.CCTV |
|
| Closed
circuit television A television system intended for only a limited
number of viewersĦMas opposed to broadcast TVĦO |
| |
| 11.C-mount |
|
| The
first standard for CCTV lens screw mountingĦOIt is defined with
the thread of 1Ħ( 2.54mm ) in diameter and 32 threads/inchĦMand
the back flange-to-CCD distance of 17.526mm ( 0.69Ħ)ĦOThe C-mount
description applies to both lenses and camerasĦOC-mount lenses can
be put on both C-mount and CS-mount camerasĦMonly in the latter
case an adaptor is requiredĦO |
| |
| 12.Coaxial
cable |
|
| The
most common type of cable used for copper transmission of video signalsĦOIt
has a coaxial cross-sectionĦMwhere the center core is the signal
conductorĦMwhile the outer shield protects it from external electromagnetic
interferenceĦO |
| |
| 13.CS-Mount |
|
| A
newer standard for lens mountingĦOIt uses the same physical thread
as the lenses made smallerĦMmore compact and less expensiveĦO
CS-mount lenses can only be used on CS-mount camerasĦO |
| |
| 14.dB |
|
| Decibel
A logarithmic ratio of two signals or valuesĦMusually refers to
powerĦMbut also voltage and currentĦOWhen power is calculated
the logarithm is multiplied by 10ĦMwhile for current and voltage
by 20ĦO |
| |
| 15.DSP |
|
| Digital
signal processingĦOIt usually refers to the electronic circuit section
of a device capable of processing digital signalsĦO |
| |
| 16.EIA |
|
| Electronics
Industry AssociationĦMwhich has recommended the television standard
used in the UĦOSĦFCanada and JapanĦMbased on 525 lines interlaced
scanningĦOFormerly known as RMA or RETMAĦO |
| |
| 17.F-number |
|
| In
lenses with adjustable irisesĦMthe maximum iris opening is expressed
as a ratio ( focal length of the lens )/( maximum diameter of aperture
)ĦOThis maximum iris will be engraved on the front ring of the lensĦO |
| |
| 18.Focal
length |
|
| The
distance between the optical center of a lens and the principal convergent
focus pointĦO |
| |
| 19.Gain |
|
| Any
increase or decrease in strength of an electrical signalĦOGain is
measured in terms of decibels or number of tines of magnificationĦO |
| |
| 20.Gamma |
|
| A
correction of the linear response of a camera in order to compensate
for the monitor phosphor screen nonlinear responseĦOIt is measured
with the exponential value of the curve describing the non-linearityĦOA
typical monochrome monitor's gamma is 2.2ĦMand a camera needs to
be set to the inverse value of 2.2( which is 0.45 )for the overall
system to respond linearly ( IĦOeĦQunity )ĦO |
| |
| 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-´[ 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-´[. 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. |
| |
