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 b) Outdoor applications may require the full range of environmental
housing protection devices. However, the system designer should consider
carefully the lower hardware costs with high maintenance levels required of
standard commercial housings which use mechanical fans for heating/cooling,
windshield wipers, etc. versus the higher hardware costs with lower
maintenance levels required for nitrogen pressurized housings which do not
require mechanical devices for environmental protection. Life cycle cost
analysis should be a serious consideration factor.
c) The ambient environment may dictate the type of housing
required. Strong sunloading in exterior applications may require the use of
a sunshade. High atmospheric dust content dictate no mechanical elements
due to lens scratching from windshield wipers, etc. The designer must
consider all aspects of the application in selecting a camera housing.
d) Dome housings are often used for surveillance applications. In
addition to being tamper resistant and providing environmental protection
for both the camera and PTZ mount, domes are generally equipped with smoked
or one-way glazing. This has the advantage of persons in the FOV not being
able to discern that the camera is "looking" in their direction. Domes
generally cost more than other enclosures, but are sometimes considered
worth the extra cost for specific applications.
6.2.4.4 Mounting. Two types of mountings are of concern for the CCTV
subsystem designer: lens mount and assembled camera mount (and housing).
For lens mounting, the "C" mounting is the industry standard. It is a
screw-in mount and has a sleeve one inch in diameter with threading of 32
threads per inch. Most lenses, even for specialized applications such as
concealed pin holes, are manufactured to this standard. Camera mounts are
available in many sizes and shapes and, like housings, are not manufactured
by the U.S. CCTV system manufacturers. Procurement of housing and mount
from the same manufacturer will assure proper mounting hardware alignment.
The prime consideration in camera mount selection is that the mount must
sturdily support the camera/lens/housing configuration. Vibrations, pole
movement, etc. will be magnified on the displayed CCTV picture. Wind
loading on larger camera housings should also be considered. Some large
lenses put an undue strain on lighter mountings, particularly with PTZ
platforms affixed. In camera mountings, the designer should remember that
for most Navy applications, heavy-duty camera mountings are most
cost-effective. Skimping in this area is false economy. For fenced
perimeters, if existing buildings, poles, etc. are unsuitable, specialized
camera poles with mounting included are available. The descriptions and
specifications of these items are available from the Naval Electronics
System Engineering Activity, St. Inigoes, MD 20684. This agency should
also be contacted for assistance on any large scale exterior CCTV system
design and procurement. The following additional design considerations
apply:
a) When computing the camera mount required, the total weight of
all components should be used. To this, an additional one to 2 pounds
should
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