| 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. |
