Examples of hidden dome Cameras
CCTV is a television system that operates on a 'closed
loop' basis. Unlike broadcast television, which is available
to anyone with a suitable receiver, CCTV pictures are only
available to those connected directly into the loop.
CCTV was first used in the 1950's and has since become an
essential element in any professional security system. It
allows both premises and the people within them to be constantly
surveyed, giving security teams and property managers' tighter
control over access and a means of meeting the challenges
posed by the rising crime rate.
In most installations, the loop is a physical link - a cable
that carries the picture from the camera(s) to the viewer(s).
Increasingly manufacturers are able to increase the flexibility
of CCTV systems by replacing all or part of the physical link
with microwave, laser, or other connections.
As well as the wide range of property security applications,
CCTV offers benefits in many other areas:
- Assisting Police authorities in the monitoring of traffic
flows and the implementation of prompt action in the case
of accidents and other emergencies.
- Supporting process industry managers as they control the
flow of work, identify bottlenecks and take corrective action.
- Monitoring of hostile environments that are not accessible
to man, such as nuclear reactors, furnaces, etc.
The versatility of CCTV is being applied to a growing range
of commercial and scientific applications, helping organisations
to improve performance and security and control costs at the
WHEN AND WHERE SHOULD IT BE USED?
Security and surveillance are the most accepted applications
for CCTV systems. With the aid of CCTV managers and supervisors
can control risks and minimise costs efficiently and with
the minimum of disruption.
As well as an effective deterrent, CCTV helps managers to
- Access to secure or private areas
- Unauthorised activities
- Theft or criminal damage
- Personal safety
CCTV has many applications in public safety; helping officials
to monitor changing conditions and decide on corrective action
in areas such as:
- Traffic control
- Crowd control
- Public access
- Staff control
- Car park security
- Shopping precinct security
- Industrial process control
CCTV offers organisations increased efficiency and the faster
detection of problems. As a result, its benefits include:
- Reduced security running costs
- Faster response to problems
- Increased peace of mind Simplicity and reliability
- Improved quality of environment for owners, operators,
and the public
- Easier identification of suspects
Many systems are available from small, one camera modulated
B & W systems which connect into the television sets within
the home, through video gate/door cameras/intercoms with individual
screens to specific rooms, to full, time-lapse recorded, multi-camera
colour systems giving surveillance and identification capabilities
from a central control point, and even signal transmission
newly developed digital recorders (see example at right),
reviewing the recorded footage has become fast and simple
along with built in features such as full multiplexing facilities,
motion detection / activation, 100Gb expandable hard drive
archive, time-lapse recording, motion activated recording,
split screen review and zoom features. Simply type in the
time and date the review is to start from and the recorder
will instantly locate and play the desired footage. The ability
to rapidly fax or email an image, (using the appropriate interfaces),
to Security or Police can be a major factor in apprehending
The comparison between standard VHS VCR time-lapse and digital
recorders is exactly the same as the difference between music
cassette and CD players with all the same benefits of instant
search, fast review etc.
In larger premises, cameras are often less visible. Covert
cameras may be mounted in smoke detectors, sprinkler heads,
thermostats or clocks. It is popular to mount cameras in ceiling
tile domes (see example at right), they are bubble-like
and tinted so no one can see where the camera is pointed.
From this vantage point, a pan / tilt / zoom camera can be
moved to follow someone around the premises. (If security
is not monitoring and operating the camera, it can be set
up to operate automatically but will not follow someone around
Video cameras used for security purposes don't look anything
like the video camera your family has at home - they're becoming
smaller and more specialized. A standard surveillance camera
might be in the neighbourhood of 4 inches long by 2 1/2 inches
wide with a lens on the end.
In circumstances requiring surveillance of trouble areas,
more obvious cameras mounted in clear domes or special outdoor
housings are generally proposed due their deterrent effect.
For reasons of security and protection we recommend that
cameras be mounted in such a way that they give a complete
field of view over the trouble areas. This generally means
that a higher position on a pole or building is better.
The human eye and the camera lens operate on completely different
lines. Although the human eye adjusts automatically to varying
light conditions, the camera is inherently less flexible.
In a CCTV system, lighting has to be 'designed in' from the
beginning if the best results are to be obtained. The type
of lighting used, and the correct positioning are vital to
Everyday 'white light' is actually a mixture of colours of
different frequencies. CCTV is more receptive to certain colour
combinations than others. The best results are usually obtained
by matching the spectral response of the camera to the light
illuminating the scene.
The amount of light reflected from an object determines how
'bright' it appears. Below are some typical reflective figures:
10 - 20%
50 - 75%
To assist in achieving good quality recordings of the subjects,
it is strongly recommended that lighting throughout the complete
area covered by the camera is of a better standard than required
as a minimum for the camera operation, (i.e. a good quality
black and white camera will require 0.05 lux at F1.2
and a good quality colour camera will require 0.7 lux at
F1.2. To give you an idea of what lux means see the table
||Typical side road lighting
||Minimum security risk lighting
||Well lit office
||Minimum for easy reading
||Clear full moon
||Passageway / outside work area
||Typical moonlight / cloudy sky
||Good main road lighting
||Typical starlight / cloudy sky
As you can see 300 lux is generally considered to be the
minimum required for easy reading, and good main road lighting
is about 15 lux, so we recommend that a minimum of 2 lux be
maintained over the total coverage area, (including at the
periphery), to ensure that you achieve your objective.
DVR NETWORKING STRUCTURE
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