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Glossary |
AC refers to alternating current electricity. Many CCTV
products use 24 volts AC, for which a separate power transformer is
required.
AC/DC refers to changing between alternating current (AC) and
direct current (DC). To switch from AC power to DC a transformer can
easily be used to regulate the current. Power inverters convert DC
current to AC current.
Amps (A) are used to measure electrical current consumption.
1 amp (A) = 1000 milliamps(mA).
Analog indicates a particular electrical signal which conveys
electronic data (i.e. a video signal or audio signal). Information
carried over an analog signal is a representation of data by
continuously varying quantities. An analog electrical signal has a
different value of volts or amperes for electrical representation of
the original excitement (light, sound, etc.) within a dynamic range
specific to the analog device.
Automatic Gain Control (AGC) refers to a circuit within the
camera which regulates image brightness levels for optimum
performance and highest video quality.
Automatic Light Control (ALC) indicates the image sensor's
ability to automatically adjust in diverse lighting conditions to
yield the most vivid video image possible.
Auto-Iris Lens is a lens with a built-in method of
automatically controlling the lens aperature for the best video
quality under diverse and changing lighting conditions. Auto-iris
lenses can be especially helpful under very low light and bright
direct forward light.
BNC (Bayonet Neil-Concelman or British Naval Connector) is
the type of connector plug commonly found on CCTV devices for video
and audio input / output connections. BNC plugs are easily adapted
to standard consumer RCA connectors using a simple one-piece plug
adapter. Required for use with plug and play cable.
Bandwidth indicates the complete range of frequencies over
which a circuit or electronic system can function with minimal
signal loss. In effect, bandwidth indicates the amount of
information and its complexity which can be carried over a signal.
More complex information requires more bandwidth for an effective
signal.
Back Lighting Compensation (BLC) indicates the image sensor's
ability to automatically adjust in conditions where lighting is from
behind the camera to deliver the sharpest and highest quality video
image possible.
Black & White Camera is typically referred to as black and
white because video image produced is in shades of gray. Only black
and white CCD cameras have the ability to utilize IR infrared
lighting. Even without infrared lighting, a black & white camera
will generally perform better in low light conditions and deliver a
crisp image.
CCD (Charge Coupled Device) is one of the two main types of
image sensors used in digital cameras. When a picture is taken, the
CCD is struck by light coming through the camera lens. Each of the
thousands or millions of tiny pixels that make up the CCD convert
this light into electrons. The number of electrons, usually
described as the pixel accumulated charge, is measured, then
converted to a digital value. This last step occurs outside the CCD,
in a camera component called an analog-to-digital converter.
CMOS (Complementary Metal-Oxide Semiconductor) is one of the
two main types of image sensors used in digital cameras. Its basic
function is the same as that of a CCD. CMOS sensors are currently
found in only a handful of digital cameras.
Coaxial Cable is the most common types of cable used for
transmitting a video signal through copper wire. This type of wiring
has a coaxial cross-section where an outer shielding protects the
actual interior signal conductor from electromagnetic interference.
In the CCTV industry, the term "coax" usually refers to RG-59 cable
with BNC-type plug ends.
Color Cameras produce video images bearing the entire visible
spectrum of colors. The color in pictures appear vivid, crisp, and
distinguished on monitoring and playback of video.
DC refers to direct current electricity. Typically 12 volts
DC, which can easily be adapted from standard AC wall outlets using
a regulated AC/DC transformer. Unlike AC current, DC flows in only
one direction within a circuit and therefore requires the correct
+/- polarity.
Digital Video Recorder (DVR) device is capable of accepting
one or more video (and sometimes audio) input signals for recording
onto digital storage media. A DVR is basically a computer
specifically designed to gather and compress video into a digital
video format for storage on a hard disk drive or other form of
digital media. Some DVRs offer built-in motion detection recording
and can be viewed remotely and played back over the internet. Some
models may easily be backed up onto external media, such as built in
cd burners.
DVR Card is a device for installation in a home PC computer
which converts that PC into a DVR digital video recorder by
gathering video and compressing it into digital information onto a
computer's hard disk drive.
Ethernet/Modem indicates a network communication device for
computer-type devices. Most DVR video recorders come standard with
built-in ethernet LAN connection (with 'RJ-45' plug) to enable
remote internet viewing and/or network operation.
Frames per Second (FPS) describes the number of full video
frames displayed or recorded within one second. True realtime video
consists of 25 frames / sec. A complete frame of video is compiled
of two separate images (or fields), so the number of fields in one
second is always twice the number of frames per second.
Hard Disk Drive (HDD) is a magnetic media storage device for
recording digital information (like that used by computers or
digital DVR video recorders).HDD Capacity indicates the amount of
information which can be stored on hard disk drive. This figure is
measured in bytes: 1 GB = 1016 MB = 1032256 KB = 1048772000 bytes.
IR Infra Red Light is a frequency of light which is lower
than the human eye's visible spectrum (in the range of 850 ~ 950
nanometers). Color cameras CANNOT use infrared light whatsoever.
However, this special band of light CAN be detected by most black
and white CCD camera. Therefore, a black and white video camera in
combination with infra red lighting can see in pitch dark
conditions. An infra red light source appears just the same as any
visible light source on a black and white camera image.
Iris An adjustable opto-mechanical aperture built into a camera that
controls the amount of lights coming through the lens.
IP Cameras (IP / Network Cameras)- Cameras can be connected Ethernet
IP networks with a built-in 10Base-T/100Base-TX Ethernet connection
to allow you to monitor and control the units via an IP-protocol
network from a networked PC. The cameras can operate on multiple
protocols, including TCP/IP, HTTP, FTP, SMTP, DHCP, and others,
depending on model. This flexibility allows you to utilize existing
LANs, WANs, or Virtual Private Networks - and even the public
Internet - to monitor remote locations without installing standalone
video networks.
JPEG (Joint Photographic Experts Group) is a standard for
compressing image data. It is not a file format, It is a compression
method that is used within a file format. Some quality is lost in
achieving JPEG high compression rates. Usually, if a high-quality,
low-compression JPEG setting is chosen on a digital camera, the loss
of quality is not detectable to the eye.
Low Light (or low lux) Sensitivity refers to a camera's
performance under low lighting conditions. Sony 1/3 " Ex-View and
SuperHAD CCD chip sets have the best low light performance.
Lux is a measure of light in terms of candle power (measured
in foot candles). Lux is often given as a technical specification
for cameras to describe the lowest level of light required for the
camera to produce any kind of an image. However, this number lists
the absolute lowest level of light needed to move ANY of the image
sensor's pixels. A lower "lux" rating indicates performance in
darker conditions.
MPEG (Moving Picture Experts Group) A standard for a digital video &
audio compression.
Megabyte (MB) is a measurement of data storage equal to 1024
kilobytes (KB).
Milliamps (mA) is a measure of electical current power
consumption. 1 amp (A) = 1000 milliamps (mA).
Zero Lux Operation refers to video imaging in pitch black
(0.0 lux) lighting conditions. Black/White cameras can use IR
lighting to yield crisp and distinguishable video images when
absolutely no visible light is available.
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