B & P Security Services
CCTV BS EN 5013-7 Design Guidelines
Selected Extracts from BS EN 5013-7
7.0 System Design Criteria
To minimise response times, cameras, monitors, video recorders,
etc. Should be continuously on, and the system should not generate
more information than the operators can effectively manage.
7.1 Surveillance Zone Determination Criteria
A CCTV surveillance equipment installation is designed to
monitor events of fundamental importance. These events might be hold
up theft, sabotage/vandalism, hazard, evacuation, etc.
Typical examples of monitoring applications are:
a) Perimeter surveillance
b) Access control
c) Safety
d) Property protection
7.2 Criteria for Determining the Number of
Cameras & their Location
Once zones and objects requiring camera surveillance have
been identified the number of cameras required can be determined by
the fields of view of the cameras equipment and system resolution
and the nature of the zones to be surveyed. Picture detail should be
consistent and adequate for the required level of service.
The operational requirement of the system and its
use, as well as site constraints and service access, may restrict
the security camera location and increase the possibility of
further cameras being required.
7.4 Camera Selection
The selection criteria should take into account the following:
a) The security camera equipment should
satisfy the operational requirement under all specified
environmental conditions
b) Safety regulations relating to the site
Points to take into consideration:
a) White balance of colour cameras
b) Electronic iris in relation to picture degrading for highlights
c) Long exposure times in relation to movement blur
d) Spectral sensitivity in relation to the type of illumination
e) External synchronisation
f) Back-up power supply
7.5 Lens Selection
Selection of the correct lens type is as important as the camera
selection. A poor lens performance can significantly detract from
the overall performance of the system. When selecting the lens the
following should be taken into account:
a) The lens field of view (indicated in the
manufacturer’s nominal figure tables) may be reduced by any overscan
in the display device
b) The illumination of the sensor in the camera is defined by the
aperture number of the lens & its transmission number, which is
dependent on the design of the lens
c) Internal lens reflections & ghosting can significantly impair the
image
d) Some zoom lenses are subject to ramping whereby the effective
aperture number of the lens increases as the focal length is
increased
e) Accuracy of the preset shots if fitted
NOTE: Having selected the camera-lens
combination, it is recommended that, for difficult scenes, a camera
of the type selected should be evaluated in conditions similar to
those to be encountered at the installation.
7.6 Recommended Object Sizes
The size of an object (target) on the monitor screen should have
a relation to the operator task, e.g. identification, recognition,
detection or monitoring. If the target is a person and the CCTV
system has an installed limiting resolution of better than 400
tv lines, the recommended minimum sizes of this target are:
a) For identification the target should represent
not less than 120% of screen height
b) For recognition the target should represent not less than 50% of
picture height
c) For detection of an intruder the target should represent not less
than 10% of picture height
d) For crowd control (monitoring) the target should represent not
less than 5% of picture height
7.8 Evaluation of Scene & Illumination
The existing lighting should be evaluated for the level,
direction and spectral content. Optimal light sources are those
which have a spectrum that best matches the camera imaging device
response.
If additional lighting is required, the number,
type, siting and power of the light sources should be determined.
7.9 Selection of the Video Transmission System
There are many methods of video transmission and
the suitability of a particular method for a given application
should be carefully evaluated.
Security video transmission may be as
simple as a single coaxial cable or as complex as a microwave link
or a mix of different transmission means.
Consideration should be given to prevailing and
potential environmental conditions in those areas where the
equipment and/or cables are to be installed.
7.9.1 Main Video Transmission Systems are:
a) Coaxial cable: The type of cable chosen should have a
characteristic impedance of 75 Ohms. For long cable runs amplifying
or amplifying plus video equalising equipment may be required to
meet the above performance
b) Twisted pair transmission: The system uses standard twisted pair
cable, typically 120-150 Ohm balanced pairs, which requires
specialised transmission & receiving equipment
c) Microwave & radio frequency transmission: Correct alignment of
transmitting and receiving equipment is essential. Systems normally
need regulatory authority approval
d) Infra red and laser transmission: This is a line of sight system
applicable only to unobstructed signal paths
e) The output of some transmitting devices can cause eye damage
therefore warning labels must be fitted according to the appropriate
safety standards. Alignment & rigidity of transmitting & receiving
equipment is important. The transmission may be affected by fog,
rain, snow etc. & the range can be reduced by such phenomena a& this
should be taken into account
f) Fibre optic transmission: Commonly available types, together with
the appropriate fibre optic connectors should be used. The
transmission system should have sufficient dynamic range to overcome
all likely system losses & a minimum of 3 cable repairs
g) Slow scan transmission: A system suitable for both public &
private telephone & data networks. Many systems are available with
widely varying connection & transmission speeds & resolution. System
selection should be carefully evaluated against the operational
requirement
7.9.2 Selection Criteria for Video
Transmission
Considerations for the selection of a transmission means or a
combination of different means are:
a) Bandwidth of the transmission path
b) Signal to noise ratio
c) Signal distortion
d) Distance to be covered
e) Interference immunity
f) Security of communication
g) Constraints in physical installation
NOTE: Signal to noise ratio and signal distortion
are cumulative and can cause picture degradation.
7.10 Control Centre Configuration
The operational requirement and personnel available are the
factors determining the number of control locations and equipment
configuration of the control centre.
7.10.3 Number of Monitors & their Screen Size
The number of monitors should be sufficient to display the
maximum number of simultaneous alarms as stated in the operational
requirement.
The monitor screen size should be selected in
relation to the viewing distance. The recommended viewing distance
is approximately 5 times the displayed picture diagonal.
The extracts above are printed with the
permission of the British Standards Institute.
Request information B & P Security Services
- Intruder alarms access control door entry
CCTV integrated security systems closed
circuit television BSEN50132/7 1996
Technical information associated with:
CCTV - BS EN 5013-7 - Design Guidelines
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