Bulking Up Surveillance
Fiber plays key role in securing cabling distances
- By Mark S. Wilson
- Sep 01, 2010
With the transition from analog to digital
video surveillance marching forward, there
remains a crucial requirement for reliable
transmission of the video signal -- especially during
today’s period of coexistence. With many legacy installations,
coaxial cable is used to transmit images
from a camera for monitoring or recording, or both.
Coax has its limitations, including restricted transmission
distance, signal degradation over long cable
runs and interference.
Networking and digital and IP technology have
ushered in Cat-5/unshielded twisted pair cables and
high-speed Ethernet, employing IP to carry the digitized
video images. In some installations, wireless
transmission -- such as radio frequency, microwave,
Wi-Fi and mesh networks -- plays a role. Most enterprise
security video designs are not totally wireless.
Instead, the technology is applied to meet certain geographic
or operational challenges.
Finally, there is fiber-optic cabling, with its interference
immunity, better inherent security, robust cabling
distances and huge bandwidth capability.
With all these choices, security end users, designers,
integrators and installers must consider and balance
the methods with the needed functionality of
cameras in regard to maximum cable run distances,
power requirements, installation issues, installation
time, quality of video, integration with other systems
Coax Can’t Go the Distance
Coaxial cabling has, for years, been the traditional
transmission method of video surveillance traffic. The
presence of a coax BNC connector on nearly every security
camera underlines this traditional method for
signal transmission. The most common coax cable is
RG-59U. It provides what many believe is an acceptable
quality video path from a camera to the head-end
out to 750 feet.
When it comes to powering the camera, many installations
employ a “Siamese” cable -- a single RG-
59U wedded to an attached 18/2 cable for both power
and video. Still, some distances will increase voltage
drop, and it is necessary to select a power supply and
cabling that match necessary voltage to distances. Today,
when it comes to new and upgraded installations
with scores of cameras, a minority uses coaxial while
a majority boast Cat-5/UTP and fiber optics.
In some ways, the security shift has been spurred
by the popularity of local area networks in most enterprises.
Information technology’s means of transmission
gravitated to Cat-5/UTP wiring, as well as fiber
optics, often as an overall communications backbone.
Cameras can be more
easily installed using existing
UTP cabling or fiber
previously laid for enterprise
network use. Corporate and
government IP-based platforms
have accelerated the transition.
That naturally has swung security
to such designs, especially when it
involves video surveillance.
UTP cabling is lighter and
easier to install, which lowers end-user installation
costs, and the material itself is less expensive than
comparable lengths of RG-59U. However, there still
remain challenges and costs when pushing analog
video signals through UTP cable. It requires conversion
of the camera’s unbalanced BNC output into a
balanced signal that can be carried on one pair of the
UTP. When reaching a head-end or recorder, the signal
must be reconverted to handle a standard BNCtype
This requires the use of a balun, which is a device
that connects a balanced line to an unbalanced line.
It allows one impedance value to be transmitted over
a cable that uses a different impedance value. A video
balun lets users send video signals over a cable not
meant for video. A common situation involving video
baluns is use with Cat-5 cable. Coax cable, which
transmits video, has an impedance of 75 ohm, while
Cat-5 has an impedance of 100 ohm.
Thus, baluns convert the original impedance to
the impedance of the cable and back. They are used
in pairs; one on each end of the cable. Transmitting
video over Cat-5 without the use of video baluns produces
ghosting images due to delays in the signal.
Both passive and active baluns are available. Passive
baluns convert the signal while active baluns
impart an amplification method to increase transmission
distance. UTP/balun uses a single pair of a
typical four-pair cable to handle the video so three
pairs can potentially provide power and pan/tilt/
zoom from a head end to a camera. Such combinations
of baluns are called hubs.
How Fiber Optics Help
Fiber-optic technology, a method of sending and
receiving information over great distances using light
as the carrier, boasts significant advantages.
The advantages of fiber-optic technology include
better quality transmission; no interference from lightning
strikes, short circuits, “cross talk,” EMI or RFI;
high voltages in fluorescent lights, card access door
strikes and outdoor lighting systems; a light weight;
stability within a wide temperature range; long service
life; more security (they are not easily tapped into or
interfered with); high bandwidth; and tech growth --
ongoing developments will increase the amount of
Considering Transmission Loss
Attenuation in fiber optics, also known as transmission
loss, is the reduction in intensity of the light
beam -- or signal -- with respect to the distance traveled
through a transmission medium. It is far less
than the equivalent loss in copper cables, leading to
long-haul fiber connections with repeater distances of
43 to 93 miles.
There is no doubt that fiber optics can handle massive
amounts of digital information across vast distances,
securely and with immunity to interference.
Such functionality is built into fiber. A cross section
of fiber cable shows a Kevlar inner wrap. Because of
this strong nonmetallic component, the cable cannot
carry lightning pulses or transient voltages from an
outdoor camera into a facility. Plus, within the fiber
core, which is composed of glass strands, a blinking
LED or laser light is unaffected by electrical and radio
With fiber, physical security can have its own
strands in the shared fiber bundle, thus achieving a
stand-alone posture while also being part of the overall
Fiber-optic cabling comes in two basic types: multimode
and single mode. Multimode fiber has a core
size of either 50 or 62.5 microns and commonly provides
connections between telecommunications systems
within a building or campus. Preferred for most
physical security applications, multimode uses lowcost
LEDs or inexpensive lasers for transmission. It is
easier to terminate and test. However, multimode has
a distance limitation -- usually out to three miles -- as
compared to single-mode. The latter fiber, with a core
size of 7 to 10 microns, typically handles longer distances of more than 50 miles in highbandwidth
Fiber is superior to copper cabling
in all performance measures. Available
bandwidth of standard multimode fiber
is estimated at 45 times that of Cat-5
UTP, while the maximum bandwidth
capacity of single-mode fiber has yet to
be reached, according to fiber-optic experts.
This is especially important when
scores of cameras can transmit their signals
over only one or two fiber strands.
Whatever the mode, fiber knocks out
Cat-5/UTP. But even though IP-based
video is gaining users, there remains a
serious distance limitation with UTP
cabling infrastructure, hindering placement
For example, if a camera is located
1,000 feet from the head end, without
any active signal conditioning at some
cost, about 37 percent of the information
will be lost in transmission, not
counting the need and cost for signal
amplification, ground fault correction
and surge protection.
Opening the Application Doorway
Almost unlimited capabilities exist for
security video transmission and PTZ
controls. In addition, since a single-fiber
strand offers bidirectional signaling, one
fiber between two points can carry multiple
streams of security video in one direction,
while PTZ control can go in the
opposite direction, all simultaneously.
Fiber within most buildings is multimode.
Some infrastructures have a combination
of multimode and single mode.
No matter the mode, there needs to be a
way to convert the video signal over to
an optical format and back again. Therefore,
devices that are part of a fiber-optics
transmission system, including receivers
and transmitters, can be combined into
transceivers, video-to-fiber converters,
connectors and adapters.
Fiber connectors come in several
common styles, such as ST (round), SC
(square) and LC (square). Devices for
interfacing physical security equipment
to fiber-optic links usually can be ordered
with either the ST or SC connector.
Various adapters convert connections,
such as connecting an ST video
fiber encoder to an SC connector on a
network fiber patch panel.
When implementing a coexistence
system of analog and digital IP, consider
the cost of analog to fiber. However,
the increasing speed of an organization’s
migration to IP will continue to
change that equation.
For example, in addition to providing
a means for transparently connecting
one type of media to another, media
conversion provides a cost-effective
method for integrating a hybrid video
security system into one seamless and
manageable whole. Cost savings can be
realized thanks to an existing, analogbased
security video infrastructure,
while coexisting with the latest technology
of IP-based cameras for video
capture, storage or analysis and for expanded
application of megapixel and
HD cameras at added locations.
In coexisting analog/IP security video
applications and when all-digital and IP
take over, fiber optics
lights the way.
This article originally appeared in the September 2010 issue of Security Today.
Mark S. Wilson is the vice president of marketing for Infinova.