| Letter A-Z |
|
AC Power
|
Alternating Current Power. In the United States, the standard AC
Power is single-phase 117VAC/60Hz and is provided from power outlets
in the house. 24V AC power can be produced from an AC Adapter. |
| AC/DC Power Adaptor |
Such as power adaptor with input:AC220V,output:DC12V. |
Angle of View
|
The scene angle that a video camera lens can show on the monitor,
like Diagonal Angle, Horizontal Angle and Vertical Angle, usually
described in degree. |
Aperture
|
The light gathering area of a lens, controlled by the iris. |
Auto-Focus Lens
|
Automatically adjusts the lens focus from surrounding scene and
keeps a moving object in focus. |
Automatic Gain Control (AGC)
|
This is a feature of many CCTV cameras that helps keep the strength
of the output signal constant, even when the light level changes.
In other words, it boosts the signal strength at low light levels,
and caps it at higher levels. |
Auto Iris (AI)
|
Cameras with an Auto Iris feature, have the ability to compensate
for large variations in light levels. Particularly useful for cameras
that need to compensate for changes from bright sunlight to dark shadows.
The auto iris circuitry is normally linked to a motorised iris drive
that physically opens and shuts the iris on the lens. Closing a physical
iris is a much better way to protect a camera from being damaged by
bright sunlight then simply using electronics to reduce the signal
strength. |
Automatic White Balance (AWB)
|
This is a feature of some cameras that automatically adjusts the
color settings to maintain the quality of the white areas of the image. |
Back Light Compensation (BLC)
|
This is a feature of cameras that automatically adjusts the image
to compensate for bright sunlight or bright lights, to give more detail
on the darker areas of the image. For example to focus on the detail
of a face of a person that has the sunlight shining from behind. |
BNC Connector
|
BNC is a bayonet style connector for coaxial cable that is most
commonly used for CCTV installations. |
Brightness Control
|
The manual bias control on a cathode ray tube or other display device
that controls the average brightness and the contrast of a picture. |
Camera Format
|
Video camera's CCD chips format; 1/3", 1/4", 1/8",
etc. |
Camera Sensor
|
"Video image sensor. CCD or C-MOS chip.CMOS sensor is a kind
of sensor that is normally 10 times less sensitivity then CCD sensor.
As human eye can see object under 1 lux illumination (full moon night
). CCD sensor normally will see better or as good as human eye in
the range of 0.1 ~3 lux and are 3 to 10 times more sensitive then
CMOS sensor. " |
CCD
|
Charge Coupled Device. One of the two main types of image sensing
device used in cameras. It operates by converting light energy into
electrical charge. |
CCIR
|
International Radio Consultative Committee; has made the technical
recommendation for the European 625 line standard for video signals. |
CCTV
|
Closed Circuit Television. It does not broadcast TV signals but
transmits them over a closed circuit through electrically conducting
cable or wireless transmitter and receiver. |
CCTV Camera
|
A unit containing an imaging device that produces a video signal
in the baseband form, usually with synchronization pulses and color
information (composite video). |
Chip
|
An integrated circuit in which all the components (resistors capacitors
and semiconductors) are micro-fabricated on a tiny piece of silicon
or specialist material (silicon on sapphire. Often used to refer to
the detector in a CCD camera. |
C Mount Lens & CS Mount Lens
|
CCTV lenses are available in two different lens mounts. "C-mount"
lenses have a flange back distance of 17.5mm vs. 12.5mm for "CS-mount"
lenses. Many of today's cameras can accept either type of lens, but
it is important to make sure that camera and lens. |
Coaxial Cable
|
This refers to cable that has a central conductor, surrounded by
a shield sharing the same axis. The shield can be made from a variety
of materials including, braided copper, or lapped foil. |
Composite Video
|
A combined signal in a television transmission. Standard format
such as NTSC, PAL or SECAM. The picture signal, blanking signal, and
vertical/horizontal synchronizing signals are all combined.
|
Compression
|
Digital video pictures can be compressed with a number of techniques.
These include, JPEG, M-JPEG, MPEG and Wavelet. |
Day and night camera
|
These cameras incorporate IR cut filters which automatically move
over the CCD sensor for daytime(color) usuage, to prevent IR light
to the CCD. At night time, the filter will be removed automatically
to bring in IR right to the CCD, and maximize the low light sensitivity
with black and white image. |
DC Power
|
Direct Current Power; can be derived from an AC adapter or from
a battery. Among DC voltages of 6, 9, 12, 24, 28, 12VDC is most common
in the CCTV industry. |
Decibel (dB)
|
The power or voltage ratio of two signals.
|
Digital Video Recorder (DVR)
|
Also known as a personal video recorder (PVR) or hard disk video
recorder. DVRs store recordings on a large hard drive, and most let
you pause and replay live television. When used with an electronic
program guide service, you can find and record shows automatically. |
DNS
|
Domain Name System. A general purpose distributed, replicated, data
query service. Its principal use is the lookup of host IP addresses
based on host names. |
DSP
|
Digital Signal Processing. It usually refers to the electronic circuit
section of a camera capable of processing or enhancing signals. |
EIA
|
Electronic Industries Association. American standard for B/W camera
system. |
Electronic Iris (EI)
|
This is an electronic implementation of an auto iris. It uses electronics
to simulate the effect of opening and closing the iris, by increasing
or decreasing the effective shutter time of the camera. |
Electronic Shutter (ES)
|
Compensates for moderate light changes in indoor applications without
the use of auto iris lenses. |
External Sync.
|
An external sync allows a piece of equipment to take its video synchronisation
from another unit, so that it can align itself with the system as
a whole. |
Field
|
One video frame is composed of two fields; one field consists of
the odd numbered lines in the frame and the other field consists of
the even numbered lines. |
Focal Length (FL)
|
The distance between the optical centre of a lens and the principal
convergent |
Format
|
The size of the cameras imager. Current standards are 1/3, 1/4 inches. |
Frame
|
A whole video image; is composed of two interlaced fields. A CCD
chip produces 30 frames per second at NTSC system and 25 frames at
PAL. |
Gamma
|
Degree of contrast in a video picture between output magnitude and
input magnitude. |
HAD
|
Hole Accumulated Diode. A type of CCD sensor with a layer designed
to accumulate holes (in the electronic sense), thus reducing noise
level. |
Image Device
|
The detector in the camera, either a tube or CCD solid state device. |
Image size
|
Reference to the size of an image formed by the lens onto the camera
pickup device. The current standards are: 1/4" and 1/3"
measured diagonally. |
Interlace
|
PAL video signals transmit odd and even lines alternately. This
is a 2:1 interlace. The two sets of lines are combined to form each
single frame. |
Internal Sync.
|
Devices with internal sync, have an internal crystal to provide
sync pulses, without needing reference from any external device.
|
Infra Red (IR)
|
Low frequency light below the visible spectrum. This is often used
for covert or semi-covert surveillance to provide a light source for
cameras to record images in dark or zero light conditions. |
IP
|
Internet Protocol. A set of rules to send and receive messages at
the Internet address level. |
IR LED
|
A light-emitting diode (LED) is a semiconductor device that emits
visible light when an electric current passes through it. The light
is not particularly bright, but in most LEDs it is monochromatic,
occurring at a single wavelength. The output from an LED can range
from red (at a wavelength of approximately 700 nanometers) to blue-violet
(about 400 nanometers). Some LEDs emit infrared (IR) energy (830 nanometers
or longer); such a device is known as an infrared-emitting diode (IRED). |
Iris
|
This is a mechanical device that adjusts to vary the amount of light
passing through the lens of a camera.
|
JPEG
|
JPEG is a standard for coding/compression of still pictures. It
is used in the CCTV systems to compress and store individual frames
of video. |
Lens
|
An optical device for focusing a desired scene onto the imaging
device in a CCTV camera. One camera can be with lenses with different
focus,such as 3.6,6,8,12mm etc .If you are not sure what lens you
should choose,please mail us for answer in detail.
|
Line Lock
|
In CCTV, this usually refers to multiple cameras being powered by
a common |
Lux
|
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 m2.
It is also known as lumens per square meter. One lux is equal to approximately
0.09290 foot candle.
|
Matrix Switcher
|
This is a device that allows any of its camera inputs to be switched
to one or more of its monitor outputs. The outputs can of course also
be video recorders. |
Monitor
|
The device used to view video pictures. These devices do not normally
have television RF frequency receivers. They normally have composite,
or component video inputs. |
Monochrome
|
This refers to a black and white image rather than a color one.
|
Motorized Lens
|
A camera lens equipped with small electric motor that enables focusing
lens, opening or closing the iris diaphragm, or changing the focal
length. |
MPEG
|
MPEG is a standard used for coding and compression of moving images.
It was developed by the Moving Pictures Experts Group. It is now used
widely for the compression of video images. However MPEG isn't just
one standard. They have developed several standards for different
uses. For example MPEG-2 is used for DVD's and set top boxes. MPEG-4
was developed for multi-media applications for fixed and mobile web
applications. |
Multiplexer
|
This is a device that takes inputs from 2 or more video channels
and combines them into one signal. This is often done by using time
division multiplexing, which interleaves frames from each channel
in such a way that they can be split out again. Frequency division
multiplexing uses different frequencies to achieve the separation
of the signals. |
Network Camera
|
This refers to a camera that is designed to record pictures and
transmit them directly over a computer network or dialup internet
connection. Network cameras normally do not have any analogue video
outputs. The images are encoded directly in one of the standard compression
techniques, such as JPEG or MPEG. |
