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CCTV
(Closed Circuit Television ) Explained In Plain
English
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CCTV, Colour and
monochrome video cameras to time lapse VCR's,
switchers and multiplexers, remote movement control,
telephone video transmission systems ... need
some plain English? - look no further, here is
a simple guide to CCTV.
The very presence of CCTV (Close Circuit Television)
cameras deters criminal activity. In business
video recordings have been effective in helping
employers and police identify criminals whilst
conducting crimes including; armed robbery, burglary,
car park robbery, credit card fraud, colleage
harrasment, computer abuse, customer returns fraud,
employee theft, shoplifting, vandalism, and more.
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Picture
courtesy of
Monarch
CCTV Ltd.
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CCTV has
its place in the home too, from watching the perimeter
and entrances to monitoring nurseries and childrens'
play areas. Often covert
( hidden ) cameras are essential at home and at work.
Hidden cameras are often a short term measure for
targeted surveillance operations and specialist advice
from CCTV Experts
should be sought and an understanding of the Data
Protection Act is essential.
Because
CCTV cameras are becoming an important part of many
company's business management and loss prevention
programs it is essential to have a reasonable understanding
of your requirements - or more importantly, deploy
the skills of a reputable CCTV
consultant.
Picture
courtesy of
Monarch
CCTV Ltd
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The benefits of implementing
a quality CCTV system include: Minimising the
risk of theft and other illegal activities. Protecting
your premises from threats such as arson, terrorism
and vandalism. They are not just there for crime
prevention and detection! Monitoring individual
employees work performance helps improve business,
Improving customer service by observing peak periods
and planning the staff rotas. By observing staff
activity CCTV can assist in staff training too
by pinpointing areas which need addressing..
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We are
laden with Acts of Parliament, Laws, Rules and Regulations
which can bring heavy fines upon us if we fail to
maintain them. CCTV can help by enhancing health and
safety standards and ensuring employees comply with
legal obligations. In so many cases a well-designed
CCTV system can help by doing the work of a much larger
guarding team, thus leaving people free to deal with
situations that arise in a more efficient and cost-effective
manner.
Choosing the right
CCTV system and having it professionally installed
is essential - it will provide you with superior
results and will ultimately save you time and
money. Remember that CCTV systems don't come in
ready made kits, so each component can be provided
especially for your needs. We will take a look
at each one of those items.
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Picture
courtesy of
Monarch
CCTV Ltd
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CCTV pictures
are displayed on monitors. Small desktop monitors
or large hanging multiscreen monitors, they show the
end product of your system - live and recorded pictures.
Monochrome, colour or high definition colour, monitors
are available in a range of sizes. Contrary to popular
belief, larger monitors do not show a wider picture,
they merely display in larger formats. In selecting
monitor size, the distance from viewer to screen will
dictate the required monitor size. Reception desks,
counters, etc. Will normally be fitted with 9"
or 12" monitors, whereby a wall or ceiling mounted
monitor showing a multiscreen display will need to
be quite large. A good surveyor will recommend a monitor
to best suit its environment.
Picture
courtesy of
Monarch
CCTV Ltd
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Medium
Resolution Monochrome, ( black & white
) with good sharp images of around 400 lines and
light sensitive down to 0.1 lux these are excellent
all-round cameras which can easily meet smaller
budgets.
High Resolution Monochrome with premium
digital technology performance of 580 line and
0.05 lux ensure superb pictures even in very dim
lighting conditions. |
Medium
Resolution Colour: Never before have colour cameras
been as good or as accessible to smaller budget systems.
Excellent for retail and good quality general surveillance,
with typical 350 lines and 1.5 lux performance.
High Resolution Colour: Full digital colour cameras
offer premium pictures with crisper definition and
excellent performance to 480 lines and 1 lux.
Day/Night Cameras: All day and all night -
one camera. Using the latest digital intelligent sensing,
these cameras offer the full performance of the high-resolution
colour cameras by day, then automatically switches
to high-resolution monochrome camera when light levels
fall. For premium installations.
What
is lux?
Lux is the standard
measurement of light. Typical levels of lighting
as recommended by the lighting industry are:
Indoor -
Warehouses
20- 75 lux -
Emergency stairs 30-75 lux -
Corridors and stairs 75- 200 lux -
Shops 75-300 lux -
Offices and reception areas 300 -500 lux
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Banks and offices 200-1000 lux -
Assembly lines 300-1000 lux
And
outdoors..... -
Full sunlight 10,000-1,000,000 lux -
Overcast day 100-10,000 lux -
Twilight 1-10 lux
Full moon 0.1-1 lux -
Overcast night 0.01-0.1 lux -
Star light, clear 0.001-0.01 lux -
Star light, overcast 0.0001-0.001
lux
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(pan/tilt) cameras can take the place of many
fixed cameras. Generally fitted with a zoom
lens, they can be remotely controlled to cover
a wide area. Used predominantly in larger retail
and commercial perimeter protection, the benefits
of a carefully positioned camera are vast. Often
housed within a dome, these cameras can spin
round and round to any position faster than
any subject being viewed, and zoom in for a
close-up picture. They can be 'taught' to 'tour
your premises, viewing key areas much more effectively.
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How
Much Will My Camera See ?
Different
lenses provide different angles of coverage.
A typical chart below will serve as a guide
but a good surveyor and a good engineer will
know what lens is best for the job. Good
CCTV engineers carry a large stock of lenses
so the correct size needed to give optimum coverage
will be fitted.
Lens size
- 2.6mm 88º
- 4mm 60º
- 8mm 30º
- 16mm 15º
- 50mm 5º
- 75mm 3º
This list is not restrictive, as most engineers
have Varifocal lenses, i.e. 2.3-6mm, 5-40mm,
to get the best available picture. It is important
to realise that wide angle does not mean the
best coverage. Detail can become too small if
too far away. An experienced engineer will fit
the correct lens to concentrate on the desired
area only, and eliminate "waste" areas.
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Picture
courtesy of
Monarch
CCTV Ltd |
By far the most
popular recording medium for CCIV. Time-lapse
VCRs using standard VHS tapes are able to provide
longer recording times than that of standard
VCRs. From smaller machines providing 24 hours
recording from one tape up to larger machines
offering recording up to 20 days or more. All
are built for industrial use and are happy working
24 hours a day, 7 days a week. Popular makes
are; Panasonic, Sony, Mitsubishi, JVC. Super
VHS (S-VHS) is now becoming more popular than
ever. Enhanced quality over standard VHS recording,
S-VHS is highly recommended for superior recorded
information. |
| Good CCTV operations
should have a tape library. These can be marked
up, allowing easy tape rotation and management.
Good CCTV installers can also provide storage
cabinets with easy tape access. Monarch
CCTV Ltd informed us that most VCR problems
they attend to are tape-related, i.e. poor/dirty
storage causing internal VCR faults. They are
are changing this through good information and
education. After all - it is your systems' performance
at risk from compromised recording quality.
Recording Digital - New advances in hard disk
recording (HDR) have made multi-camera recording
onto hard disk a natural progression from tape
based systems. - Pictures are stored directly
onto a hard disk, and when this memory is full
the information is then transferred to digital
tape for storage. |
What
if I have more than one camera?
| Where two or
more cameras are installed at a site, a means
of control is used. From simple camera switchers
to large multiplexers allowing multiscreen displays,
we can design the best option for your requirements.
Camera switchers allow manual or automatic switching
of pictures when recording. What you see is
what you record. This is the simplest and cheapest
form of control but restrictive in that information
can be lost when other pictures are displayed.
Multiplexers are a large step forward from switchers.
They allow all cameras to be recorded to tape
simultaneously, regardless of the pictures being
displayed. Multiplexers can also provide multiscreen
displays of many cameras. |
Picture
courtesy of
Monarch
CCTV Ltd |
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