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Coaxial Cable
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A cable with a central conductor that’s surrounded by a
shield sharing its same axis is called a coaxial cable.
It’s used primarily for carrying high frequency or
broadband signals. RG59 video coaxial cable is
used for digital video recorder (DVR) installations.
Covert
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A CCTV surveillance system that uses hidden cameras and
lenses is considered to be covert.
Ethernet
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Ethernet can send information either wirelessly (known
as WiFi) or, more commonly, over wires. It runs at
10mbps, and all terminals connect to a single common bus
(sometimes called a highway). It serves as the
IEEE (Institute of Electrical and Electronics Engineers)
802.3 standard, which ensures that networks adhere to a
particular set of technical standards. A new
type, known as Fast Ethernet, or 100Base-T, runs at
100Mbps, and the newest type, Gigabit Ethernet, runs at
1gigabit per second.
Field of View
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This is the total height and width of the view seen
through the lens.
Focal Length
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Focal length is measured in mm or inches, and 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.
fps (Frames Per Second)
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In the field of video surveillance, fps means the number
of frames a DVR is able to capture per second.
Three steps are required: video capture, compression,
and storage. Each step affects a DVR’s true fps
number. The use of DSP chips in both IP cameras
and DVRs can assist in the optimization of fps.
Frame
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One complete picture is called a frame, and it contains
525 lines (NTSC) or 625 lines (PAL).
Impedance
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Measured in ohms, impedance describes the input and
output characteristic of an electrical system. For
the best signal quality, both input and output
impedances should be equal, with CCTV systems having
75-ohm impedance throughout.
Infrared camera
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These cameras are well suited for surveillance of low
light areas or areas with no light at all.
Infrared LED’s surround the lens and shine infrared
light, illuminating the scene. They usually have a
fixed focal length lens and present b/w images during
low light (though some offer color in the day and b/w at
night).
Iris
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The section of the lens adjusted to control how much
light passes through it and onto the CCD chip is called
an iris.
JPEG (Joint Photographic Experts Group)
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This 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.
Lens
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This is the device responsible for focusing the image on
the CCD, and most offer adjustable focal length and
aperture.
Lux
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Used more often than lumens when discussing security
cameras, 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. Look for 0.2 lux or less when choosing a
low-light camera, and 2 lux or higher for daylight
cameras.
MPEG-4
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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
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A video surveillance device with multiple video inputs
and one video output is called a multiplexer.
Multiple security cameras are connected to it and their
images can be presented on one monitor. A front
panel displays the buttons that toggle each camera, and
the signal from one camera or a combination thereof can
be displayed. Multiplexers are simpler to use as
compared with similar procedures on a DVR which normally
requires a system login, operating a keyboard and
controlling a mouse.
Network Camera
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Also known as a Network IP Camera, this is a stand-alone
camera that uses a standard web-browser to view live,
full motion video from a computer network, including
over the Internet. They often feature an embedded
OS (operating system) and features like: FTP of
images, web server capability, and built-in motion
detection.
Outdoor Camera Housing
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A protective shell for security cameras to be placed in
outdoor environmental conditions, these housings
typically include cooling fans for summer use and
heaters for winter use. The heaters also eliminate
fogging of the glass anytime this occurs.
Outdoor Dome Housing
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This housing is dome shaped for insertion of dome
security cameras, is very tamper resistant, and allows
for PTZ.
Passive
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If a system component is non-powered, it is considered
passive.
Pelco-D
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This Pelco created protocol is used to control PTZ
security camera movement.
Pinhole Camera
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Perfect for covert surveillance, this quarter sized
camera is nearly impossible to detect. With it’s
small size comes limited abilities though, primarily a
small lens and limited zoom capabilities.
Pixel (Picture
Element)
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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.
Power supply
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Most security cameras utilize 24V AC or 12V DC power
supplies. A power supply is usually plugged into a
regular electrical outlet or part of a centralized power
supply.
PTZ Camera
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PTZ stands for Pan, Tilt, and Zoom. These cameras
are usually remotely controlled by software or a
joystick. PTZ cameras are used when active real
time monitoring with the ability to point the camera’s
viewing area to a specific action or event is desired.
PTZ controller
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The controller used to control PTZ camera movement,
usually software or a joystick.
Quad
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Utilizing digital video, this piece of equipment
displays signals from four surveillance cameras on one
monitor.
Regulated power supply
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A DC power supply with a minimal ripple factor is
considered to be regulated.
Remote monitoring
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This allows an off site user to monitor surveillance
camera feeds, so a user can survey a site regardless of
their location from it. The transfer of data from
camera to user can be either over the Internet or the
Ethernet, with IP cameras being suited to the task.
RF (Radio Frequency)
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In order to be broadcast across a wireless network,
video signals must be modulated into a RF signal.
RG-59
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More commonly used than RG-11 for CCTV, this coaxial
cable transmits video signals of up to 230m.
Sequential switcher
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A sequential switcher enables the simultaneous display
or recording of multiple surveillance cameras.
Siamese Cable
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RG59 Siamese cable is a heavily shielded cable which
contains both the video (COAX) cable and the power cable
(18 gauge 2 conductor) in one jacket. The advantages to
using this cable is that its more durable, and you can
run it long distances without interference. Also, you
can cut each camera run for the exact length that you
need. The disadvantages are that it doesn't contain an
audio cable (so you have to run that separate if you
need it) and its a little more involved to use.
Telephoto lens
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In order to make distant objects appear larger, cameras
require a telephoto lens.
Tracking
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A zoom lens that can stay in focus while zooming from
wide angle to telephoto position is said to be
tracking.
UPS (Uninterruptible Power Supply)
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Justifiably popular with many electronics users, a UPS
stores electricity in a battery and supplies power to a
system (allowing a user to shut down w/out losing data
or continue for a specific time period) during a power
failure.
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