Video Surveillance Introduction
From a single camera and monitor to
complex video surveillance systems with hundreds of cameras,
multiple operators, and digital recorders, closed circuit
television (CCTV) systems can provide security for a wide
range of businesses.
A good CCTV system can make your
business safer, more efficient, and less prone to theft and
accidents. Specifically, CCTV can provide many benefits:
- reduce shrinkage by catching
shoplifters
- deter potential thieves
- monitor cash registers
- record evidence to prevent bogus accident claims
- identify visitors and employees
- monitor hazardous work areas
- increase security in and around business premises and
parking lots
- meet insurance requirements
The most basic CCTV setup would be a
single camera connected directly to a monitor and a recorder
to store the video. While a setup like this could help
security in some cases, it is unlikely to be enough for most
businesses. Most situations call for multiple cameras. In
some cases, you may even want a moveable camera to cover a
large area. This Buyer's Guide will help you
understand what goes into a CCTV system and how to make a
successful purchase.
Evaluating your CCTV needs
Before starting to compare systems or
choose potential vendors, sit down and consider your CCTV
needs carefully.
First, consider what you want to
monitor. General comings and goings? Vehicles? Do you want
to see faces, merchandise, crowds? Once you decide what you
want to see, choosing components will become easier.
Next, decide what picture quality you
need. Quality can refer to both how detailed the image is
and how fast the frame rate is. Frame rate is simply a
measure of how many individual pictures make up the video.
"Full motion", what you see on television and on VHS tapes,
is 30 frames per second, or fps. Most often, security
systems record at slower rates, which result in more
jerky-looking images but saves tape or hard drive space,
allowing longer periods of time to be recorded.
Think about how your system will be
monitored. Will you simply record at all times, and only
review the tape when a problem occurs? Or will you have a
dedicated employee watching for trouble? Also, with multiple
cameras, you have the option of connecting each to its own
monitor, or combining multiple images onto one monitor.
You should also decide whether your
priority is to deter potential crimes or to catch
perpetrators. Both can be important, but your priority will
influence your purchasing decisions. If you are more
interested in deterring certain activities, large, visible
cameras are your best bet. Trying to catch criminals on tape
without them being aware of it requires hidden cameras,
which cost more both for hardware and for installation. If
your monitoring target is internal, you run the added cost
of having to hide and secure the recorder and monitor as
well.
There are many technical terms and
specifications that dealers will refer to when discussing
security cameras as part of a CCTV system.
The basic technology behind most
security cameras is the Charge Coupled Device (CCD). CCDs
convert the images that come through the camera's lens into
electronic impulses. CCDs provide a good combination of low
price and quality picture for security applications.
Camera formats are measured in
inches: most cameras fall between 1/4" and 1". This refers
to the usable image size created inside the camera. For most
security systems, a small size is fine - 1/4" or 1/3"
cameras dominate CCTV sales. Larger formats do not
necessarily result in better images, but can be advantageous
in dimly lit situations since they are able to gather more
light.
Color vs. black and white
Since prices have dropped significantly, many businesses
today opt for color cameras over their black and white
models. For security and evidence purposes, color cameras
are better--sending security guards after "the man in the
blue coat," for example, is much more difficult when you can
not tell what color the coat is.
While black and white cameras can
operate better than color cameras in extremely low light
situations, most small to medium sized businesses use CCTV
in well-lit indoor environments. In addition, many
high-quality color cameras today can switch to black and
white mode when necessary. Some vendors do not even sell
black and white cameras any more.
Resolution
Resolution refers to how detailed a picture the camera can
see. The measurement to look for is horizontal TV lines (TVL).
A normal CCTV picture is around 350 to 400 TVL, with high
resolution getting up to 480 or 550. Upgrading a camera's
resolution can cost as little as $50.
You need to make sure your entire
system is capable of supporting that resolution. If your VCR
records 350 lines and your monitor displays 400, the money
you spent to upgrade to a camera with 500 lines is
completely wasted. In the end, the small cost to upgrade
your camera may be multiplied by the costs to upgrade other
equipment.
Note: do not be impressed by pixel
measurements in the hundreds of thousands. TVL is a more
consistent measurement.
Other specs Signal
to noise ratio (s/n) indicates how much "signal," or actual
picture information, the camera transmits, as opposed to
"noise," which comes across as static. A s/n ratio of 40db
indicates that the signal is 100 times the noise, which
results in an acceptable picture with some fine grain or
snow. 30db results in a poor picture, and 60db produces an
excellent picture with no static visible. Keep in mind that
noise can be introduced by other components in addition to
the camera.
Sensitivity to light is measured in
lux. A sensitivity of 2 lux means the camera can see fairly
well by the light of a 40W fluorescent bulb; 0.5 lux cameras
can make out images outside on a dim night. Your needs will
depend on the lighting in the area being filmed, but lux
ratings should not be the most important aspect of your
camera decision.
Surveillance Camera Peripherals
Along with your CCTV camera, you need
several peripherals to get your video surveillance system
working.
Lenses
As with regular cameras, the lens on a security camera
determines how wide an image is created and how much light
is let in. Lenses are generally sold separately from
cameras.
The lenses you purchase should match
the format of your camera: 1/4" lenses work best with 1/4"
cameras. It is possible to use a larger format lens than the
camera calls for, but it is not recommended.
You also need to decide what type of
lens you need. Fixed focal length lenses offer only one set
field of view and are the least costly. To change the
resulting image, you need to switch lenses. Variable focal
length lenses and zoom lenses offer greater flexibility,
allowing you to adjust your image's field of view. Motorized
zoom lenses, the most costly type available, give you the
ability to control your cameras remotely. If you want to
zoom out for general surveillance and in for detail when you
spot suspicious activity, motorized zooms are the way to go.
If you will be using the CCTV camera
outdoors, look for a lens with an automatic iris. As in the
human eye, the iris of a lens is what controls the amount of
light coming in to the camera. Automatic irises can
significantly improve performance for outdoor cameras, where
light levels vary considerably. However, you can save money
and use a manual iris lens when the scene illumination never
changes, for example in an illuminated store or office.
Pan, Tilt, Zoom
For advanced security applications, you may want a pan,
tilt, zoom (PTZ) camera. With the right equipment, a camera
operator can pan (scan left and right), tilt (look up and
down), and zoom in and out. The significant catch is the
cost: PTZ systems are considerably more expensive than fixed
cameras.
Housings
Cameras may need to be protected from potential vandalism or
from the elements. Housings can range from simple coverings,
to impact-resistant protection, to outdoor housings that
include heaters and blowers for cooling. A more specialized
type of housing is the dome: tinted Plexiglas hemispheres
that prevent subjects from seeing which direction a camera
is pointing. Choose the right housing based on the placement
of the camera and its expected usage.
CCTV Security Camera Monitors
Selecting a monitor for your CCTV
system is a relatively minor decision, but there are a
couple of important points to keep in mind.
First, make sure to purchase a
monitor specially to handle the type of use it will receive.
Televisions are not good monitors, since TVs are built to be
on for a few hours per day, not the 8 to 24 hours per day
they will endure. In some cases, computer monitors do make
acceptable substitutes. Flat-panel LCD screens make great
CCTV monitors for larger systems because they take up little
space, have excellent resolution, and generate less heat
than regular monitors.
As discussed earlier, make sure your
monitor resolution matches your cameras. Buy a monitor with
lower resolution and your camera's capabilities will not
come through; buy one with higher resolution and you are
throwing money away. And of course, make sure you buy color
monitors if you opt for color cameras.
Also consider the size: a 9" monitor
may be sufficient if the operator is sitting directly in
front of it, but a 15" monitor is the smallest you should
choose if you plan to combine images from multiple cameras
onto one monitor. Merging multiple images onto one screen
can be an effective way to save space, and appropriate if
there is a dedicated employee who has the ability to zoom in
on suspicious activity.
Video Security System Recorders
Recording is essential to the
effectiveness of any security system. Without recording, you
need to have an employee watching a monitor at all times -
hardly a cost-effective solution. And even if you spot
suspicious activity, without a recording, you have nothing
to use in court.
Almost all CCTV systems include some
sort of recorder to store the images the cameras capture.
Only a few years ago, the universal solution was the
familiar VCR. However, the introduction of digital video
recorders (DVRs), which record onto hard drives instead of
tape, has dramatically changed the situation.
DVRs offer so many advantages over
VCRs that they have rapidly taken over as the CCTV recording
solution of choice:
· Ease of locating events - Instead
of fast-forwarding through hours of tape, DVRs can instantly
retrieve images from any specific time or date, or
automatically skip to the point on a recording when
something changed.
· Storage quality - Like all tapes,
video cassettes start deteriorating almost immediately once
you record on them - and the problem gets worse every time
you reuse them. DVR recordings have no degradation at all
since they are stored onto a hard drive.
· Multitasking - While analog VCRs
can either record or play, most DVRs can do both at the same
time, letting you review images while still recording.
· Smart monitoring - The DVR can be
set to take one picture per second or less - just enough to
create a running record. However when it detects motion, it
can automatically bump the recording speed up to full (30
frames per second), getting every detail of the unauthorized
activity.
For businesses that do not want to
constantly change tapes, DVRs are definitely the way to go.
While security VCRs usually offer a time-lapse mode that
lets them for long periods of time, the resulting images are
not a good record of events - they record only one snapshot
every eight seconds. To get higher quality, you need to
change tapes every day or more often. DVRs, on the other
hand, can record for weeks or even months.
DVRs are more considerably more
expensive than VCRs, which is their only major drawback.
However, the DVR prices have fallen considerably over the
last year and will continue to do so. Already, low-end DVRs
and high-end VCRs are in similar price ranges, and most
manufacturers have stopped introducing new VCR models.
Despite the increased cost, we recommend CCTV system buyers
purchase a DVR whenever possible.
Choosing a DVR
As part of your CCTV shopping preparations, decide how much
quality you need out of your recorder. There is no magic
number or spec here: you need to decide how "good" the
recorded picture needs to be, either for your own use later
or possibly to use in court. Once you decide this, you will
be able to look at samples on the DVRs you are evaluating
and see if they meet your standard. Vendors may be eager to
throw compression settings, pixel counts, and other
statistics at you - but those numbers are irrelevant if the
picture itself does not offer the detail you need for legal
or investigatory purposes.
The size of the hard drive will
dictate how much you can record. On the low end, an
80-gigabyte (GB) hard drive will store about five to eight
days of full-motion video from one camera. Most of the time
you will not be recording full motion, so this is much more
than it might seem. For most businesses, spending a little
extra to get 120 or 240 GB is a worthwhile investment. Units
expand up to 18 terabytes or more, which can store many
cameras' worth of data for long periods of time.
Replaceable hard drives are a cheap
way to boost storage capacity. With some DVRs, you can buy
additional hard drives for as little as $100 and swap them
in and out as you need. This gives you the advantage of
being able to store your data separately from the main
security system.
You will also need to consider how
many cameras you want to connect to the DVR. Keep your
future expansion needs in mind - buying a higher-grade model
to get more inputs and more storage space can save you
considerable money in the future. The DVR will also function
as a multiplexer, putting up to 16 cameras on one display
and allowing operators to call up any one image for closer
inspection.
Also, if you ever have to use your
security images - in court or in other ways - you will need
to be able to export the video. This is an important
consideration: some systems let you create industry-standard
.avi files, which can be played on any PC, and burn them to
CD. Others only allow you to export proprietary formats that
can only played on the same brand player. Most DVRs do offer
the option to connect a standard VCR - this allows you to
simply tape the digital recording onto a standard VHS
cassette.
Choosing a VCR If
you decide to save money by going with a VCR, make sure you
purchase a model built for security system usage, not a
consumer VCR. Purpose-built security VCRs offer far more
reliable operation than home models, so they can stand up to
constant operation.
The main feature to look for in a VCR
is how many hours it can record: models range up to 960
hours on a standard tape. Remember, though, that these
extended recording times result in fewer frames per second.
Be aware of the hidden and ongoing
costs of VCRs. Buying, rotating, and replacing VCR tapes can
be expensive and time consuming. Constant usage creates
quite a bit of tape debris inside the machine, requiring
expensive regular maintenance. And in addition, if you have
multiple cameras, you will need a multiplexer - a separate
piece of hardware that combines multiple video images into
one - to avoid purchasing a separate VCR for each camera.
Connecting a CCTV Surveillance
Camera
There are several ways to connect
cameras to the rest of your CCTV system.
The most common is standard coaxial
cable, the same cable used to connect video equipment in
your home. Some installers use unshielded twisted pair (UTP)
cables, like the CAT5 cable used in many computer networks,
because they can reduce interference caused by electrical
currents. A simple switching device called a balun can be
used to connect coaxial lines to UTP, so you can combine
both in a single system. UTP is cheaper than coaxial cable,
so for very long runs, this may be an advantage.
Casinos or banks with complex systems
consisting of many cameras may want to upgrade to fiber
optic connections. With this setup, bandwidth is
considerably greater, allowing many signals to be carried on
the same wire. In addition, security is improved because
tapping a fiber optic line is very difficult to do without
disrupting the signal.
Wireless In most
cases, wireless connections are not recommended for video
surveillance systems. While wireless technology has taken
off in recent years, it simply has not reached the level of
reliability that CCTV users demand. The frequencies they use
are subject to interference from cordless telephones, air
conditioning, fluorescent lighting, and almost anything with
an electric motor. Users will have to expect interference,
usually resulting in a snowy picture. In addition, cameras
need electrical power - so you will have to run one wire to
the camera even if the video connection is wireless.
There are situations where wireless
is the way to go: connecting across a public street, for
example, where digging a trench is not a practical solution.
Wireless systems are also better suited for rural areas,
where there are fewer potential sources of interference. In
these cases, wireless transmitters can make expensive or
potentially impossible installations feasible.
Installation of wireless systems
requires specific expertise to diagnose problems and
fine-tune the setup, so make sure your vendor is experienced
with wireless setups if you choose to go this route.
Choosing a CCTV Integrator
The overall success of your CCTV
system can hinge on the expertise of the installers who set
it up. There are many important factors to take into
consideration that require an expert understanding of
lighting, optics, wiring, security, and more. In other
words, your experience connecting your home TV to the DVD
player does not mean you should set up your business
security system!
In the CCTV industry, businesses
typically buy from integrators or dealers. These vendors
usually work with multiple manufacturers to offer a range of
products, as well as installation and support. As with most
business purchases, there are several key factors to look
for when choosing a CCTV vendor.
Experience
A vendor's experience in the industry is a significant
indicator of the firm's reliability and long-term stability.
You will want to be able to work with your chosen vendor on
an ongoing basis as you expand or upgrade your system, so
choosing someone who will be around next year is important.
Specific experience with businesses of your size and in your
industry is also desirable: large warehouses may present
problems that a vendor who specializes in small retail shops
may not be prepared to address.
Installation
The quality of a CCTV installation can have lasting effects
on your business. Qualified installers will not take a
standardized approach to installation: they will analyze
your needs and make sure you get a system that is customized
to your location and business needs. They will also provide
enough training and documentation to make sure your staff
fully understands the operation and maintenance of your
system.
Facilities
Visiting vendors' facilities can be a great way to get a
sense of their operations. You will be able to check out
their repair shop and get a sense of how busy they are. You
may want to ask for an organizational chart or a tour of
their help desk. Depending on your support needs, proximity
may or may not be important to you - if you plan to rely on
telephone support and shipping components back for repair,
it will not matter, but if you expect field technicians to
come to you, distance from the vendor can be a factor.
Demonstrations
Nothing will give you a better sense of how well a CCTV
system achieves your goals than seeing it in action. Some
vendors conduct on-site demos, which gives you the added
advantage of being able to see how the hardware looks in
your location. Others will invite you to try the system in
their office, which gives you that facilities tour we
discussed, or will set up on online demo, which is helpful
if you plan to view images remotely.
References
Another familiar way to investigate CCTV systems integrators
for your business is to ask for references to other
customers - make sure to ask for references that are in
business similar to yours. Of course, you will be referred
to the vendor's most satisfied customers, but you can still
learn quite a bit from them. Here are some sample questions
to ask the references:
- How has the CCTV system
accomplished the goals you set for it?
- Are you happy with the overall
quality of the images, both live and recorded?
- Was the initial installation
sufficient for your needs? Or did you have to add components
or upgrade?
- What do you wish you had done
differently?
- Have you needed any support or
repairs? How did the vendor respond?
- Do you know of any one else who
uses this system? This can get you additional references to
speak to, some of whom might be more candid.
- If you had to say one negative
thing about the system/dealer, what would it be?
Video Security Systems Pricing
There are many components to a CCTV
system: cameras, monitors, recorders, and cabling to connect
the system. Add in the need for a quality installation, and
it should be apparent that shopping by price alone is not a
good approach. Some dealers will put together low-end
packages to try to lure price-conscious shoppers - these
systems suffer from lower quality, shaky reliability, and
will not last for years and years the way higher quality
systems will.
On the Internet, you can find
complete CCTV packages of 4 to 16 cameras, including a
monitor and VCR. Often they look like great deals - and most
of the time, they are too good to be true. Low-quality
components and a lack of support combine to create an offer
that can do more harm than good to your business.
A very rough rule of thumb to use for
pricing a complete, installed system is $500 to $1000 per
camera, plus the cost of your recording device. This depends
quite a bit on the types of hardware you choose and how you
set it up - read on for a more thorough breakdown.
Cameras and lenses
Basic CCTV cameras are not very expensive. Because the
hardware cost is fairly low, it is worth spending a little
extra money to get better system performance. Brand name
cameras can be found for $150 to $250, and are often a
better investment than a no-name camera. Prices vary
according to features as well -- larger formats, higher
resolution, and better sensitivity all drive prices up.
Hidden cameras, concealed in everyday
objects like clocks, smoke detectors, and calculators, run
$100 to $200. PTZ cameras are far more expensive, running
$800 to $5,000 for one camera.
- Know what you want to see. Knowing
exactly what you want to see in the monitor and on
recordings - both the scene and the quality - is the single
best way you can prepare for.
- Avoid dummy cameras. While they may
deter some problems, they also can create a legal liability
by creating an expectation of safety when none exists.
- Put up signs. Highly visible
signage that lets customers and employees know that they are
being filmed can greatly increase the deterrent effect.
|