A B C D E F G H I J K L M N O P Q R S T
U V W
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Enables the camera to open or close the diaphragm to
adjust the amount of light passing through the lens. It is useful in protecting the CCD image sensor from damaging
bright lights.
Automatic Gain Control
(AGC)
A circuit for automatically
controlling amplifier gains in order to maintain a constant output voltage with
a varying input voltage within a predetermined range of input-to-output
variation.
Balun is short for Balanced-Unbalanced. It is a device
used to interface between balanced lines and unbalanced lines. In CCTV, it is a
device that converts twisted pair to co-axial.
BNC
BNC is
the type of connector plug commonly found on CCTV devices for video and audio
input / output connections. BNC has a locking design, and are easily adapted to
standard consumer RCA connectors using a simple one-piece plug adapter.
BLC - Back Lighting
Compensation
BLC is a feature that automatically brings more detail to
darker areas of an image when bright lights (usually shining from behind)
obscure it.
The C-mount lens is found in older versions of security
cameras, and has a flange back distance of 17.5mm. In order to achieve a
focused image, a 5mm ring must be inserted between the camera and lens.
CCD – Charged Coupled
Device
CCD is a solid-state
semiconductor element that converts the light energy that enters a camera
into an electrical charge, which is then converted into an electronic image.
CCTV – Closed Circuit Television
CCTV is a private video system within a building (or complex) used to visually
monitor a location for security or industrial purposes. CCTV
pictures are viewed and/or recorded, but are not broadcast.
Coaxial cable (Coax Cable)
A cable with a central conductor that’s surrounded by a shield sharing
its same axis. Coax is
the same type of cable used by cable companies to send television into the
home.
Composite Video
Composite
video is the standard type of analog
video signal utilized by most CCTV video cameras. A composite video signal has the correct phase rate, luminance,
and chrominance information to be compatible with video format such as NTSC,
PAL, etc.
Compression
Compression refers
to the computer software technique the codec in a DVR system uses to convert
the video signal to digital format so it can be compressed and stored on digital
media like a hard disk drive, DVD, or CD.
Uncompressed video would require massive processing power and nearly
unlimited storage space and is, therefore, impractical in real-world
applications.
CS-Mount
CS mount lenses offer a longer focal distance than their C
mount predecessors. They have a flange back distance of 12.5mm.
Because they are more practical for compact cameras, CS mounts are used in most
modern cameras. A 5mm spacer ring (known as a C ring) enables CS cameras
to also use a C mount lens.
It is a camera that detects low light situations and
removes the IR cut filter automatically to function as an infrared camera. To avoid color distortions, the camera often
switches to black and white mode.
Digital Video
Digital Video is video that has
been compressed into digital information for storage onto digital storage media
like a hard disk drive, CD, or DVD. The quality of digital video will vary
depending on factors such as the camera quality and compression method.
It is the rotation of IP addresses such that every time a
user logs onto the Internet, their IP address changes. This is done for
Internet security purposes, either by the user or by their ISP.
A field is one half of a frame, with 262.5 lines in the
NTSC standard. Interlaced television
monitors display their images in two steps. The first step paints every
other line, while the second paints the remaining ones. Fields
per second and frames per second do not mean the same thing, which is a common
misconception. The number of fields per
second is always twice as high as the number of frames per second. Sixty fields are transmitted each
second on Real-Time display.
Fixed Lens
A fixed lens has a set focal
length with a specific field of view, which cannot be changed. Any camera
without a vari-focal or power zoom has a fixed lens. Cameras with fixed lenses
are focused to infinity, which means that although the user cannot manipulate
the field of view, everything in the picture beyond a few inches will be clear
and in focus.
Focal Length
Focal
length is the
distance between the optical center of the lens and the point on which it
focuses. A lower focal length results in less magnification with a
greater field of view, and vice versa for longer focal lengths. Security
cameras usually have a focal length of ¼”, 1/3”, or ½”.
Frame
The total area (occupied by the television picture) that
is scanned while the picture signal is not blanked.
FPS (Frames per Second) Display Rate
Also know as refresh rate, it indicates the number of
frames per second a device will display
on a monitor for simultaneous viewing.
The rate at which each camera is displayed differs from the number of
frames per second the recorder captures for playback.
FPS (Frames per Second)
Record Rate
It describes exactly how many frames per second a video recorder can
actually capture.
GUI –
Graphical User Interface
It refers to the graphical interface of a computer that
allows users to click and drag objects with a mouse instead of entering text at
a command line. Two of the most popular operating systems, Windows and the Mac
OS, are GUI-based.
It is a color filter that
blocks the infrared light from reaching the image sensor. Infrared light, which is invisible to the
human eye, can be detected by the image sensor and can distort color during
daylight. All color cameras has this
filter.
An adjustable aperture built into a camera lens to permit
control of the amount of light passing through the lens.
JPEG (Joint Photographic Experts Group)
It is one of the most common file formats for compressed
photo images. A small amount of data, though not noticeable enough to be
significant, is lost in the compression process, making JPEGs a lossy
compression algorithm.
Refers to the ability of a lens to transmit light,
represented as the ratio of the focal length to the diameter of the lens. A
fast lens would be rated <f/1.4; a much slower lens might be designated
as> f/8. The larger the f-number, the slower the lens.
Low Light (or low lux)
Sensitivity
It refers to a camera's performance under low lighting
conditions. Specifications offered by
CCD manufacturers list the absolute lowest light level at which some pixels
will be altered.
Lux
A lux is a unit of illumination. It measures the amount of
uniform light that falls on one square meter (expressed in one lumen per square
meter). Security camera specs use the lux to indicate how much light they
require to operate, with lower lux levels indicating a camera as more effective
in lower ambient light. The number lists the absolute lowest level of light
needed to move any of the image sensor's pixels.
Even though it’s not as efficient as MPEG-4, the MJPEG is
still an effective way of creating video from the sequencing of JPEG images.
MPEG (Moving Picture Experts Group)
One of the most common coding standards for internet transferable
video images, the MPEG format is playable on nearly all video players.
MPEGs use lossy data compression. MPEGs first predict the initial picture
content, and then code differences between that and the copy, as well as any
extra information.
MPEG4 has a newer codec and supports 3D content, low bit
rate encoding, and support for Digital Rights Management, which controls the
use of copyrighted digital work. MPEG4 is used for web streaming media,
broadcast television, videophones, and CD distribution. MPEG-4 is widely
used in video surveillance, and has recently been improved to the AVC standard.
Multiplexer
It is a video switching device
that accepts video input from multiple cameras and converts them to all display
on one monitor and / or video recorder.
NTSC
(National Television Standards Committee) standard
It is the standard color video format used in North
America, South Korea, Japan, Central America, and a number of South American
countries. In real-time it broadcasts
30 frames per second at 525 lines of resolution
It is the standard color video format used in most of
Europe, Asia, Israel, and many other places in the world. In real-time it
broadcasts 25 frames per second at 625 lines of resolution.
Pixel
Pixels are the smallest possible display unit of visual
information available for building a graphical image. It is also the
basic unit of a CCD chip, with most CCD chips being comprised of over 300,000
pixels.
PTZ stands for Pan, Tilt, and Zoom. PTZ cameras are
usually remotely controlled by software or a joystick. PTZ cameras are
used when active monitoring with the ability to point the camera’s viewing area
to a specific action or event is desired.
It is a
common connector plug for standard consumer video and audio equipment.
Real-Time Video
Any picture having 24 or more frames per second appears
continuous, or in real time. In NTSC
format, real-time is considered 30 FPS.
In PAL format, real-time is considered 25 FPS.
Resolution
It is the degree of sharpness
of a displayed or printed character or image. On screen, resolution is
expressed as a matrix of dots. For example, the resolution of 640x480 means 640
dots (pixels) across each of the 480 lines.
As each piece of CCTV equipment included within a system contributes to
the overall image quality, the resultant image can only be as clear as the
piece of equipment with the lowest resolution. If you are using a
high-resolution monitor together with a low-resolution camera, the monitor can
only display low-resolution images.
RS-232
This is the communication standard that applies to PC
serial communications. RS232 is commonly used as the mechanism for
sending instructions that control PTZ security camera movement.
The ratio between useful television signal and disturbing
noise or snow.
This is an IP address that doesn’t change. Any
computer can connect to it, thereby making video surveillance systems with
static IP addresses remotely accessible from any location on the Internet.
It is a type of lens that can
vary its focal length in order to zoom in on images. An auto-iris feature is needed to accomplish this.
Video Motion Detection
This is a software feature,
which can detect motion in a camera's field of view and begin recording based
on this motion detection. It can be adjusted in sensitivity, and can select and
deselect areas in each camera's view for motion detection function.