Home' RTCA Documents for Review : DO-230H FRAC Contents 167
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Camera detector performance is non-linear, dropping as the quantity of photons delivered by the objective
Camera, filter and lens selection must deal with these issues for night surveillance to be successful,
especially if video analytic functions are used because they require clear, sharp images in most instances.
For monitoring the fenced perimeter at night, distance considerations will often dictate the use of long focal
length lenses. Lens focal length and camera field-of-view are inversely related; as the focal length increases,
the field-of-view decreases.
For perimeter surveillance, camera format should be selected to provide the desired horizontal field
coverage when matched with an objective lens having the focal length and the relative aperture needed for
the viewing distances. These conditions generally favor the use of 1⁄2-in or larger format cameras.
Stabilization software is also available which significantly improves the ability view video when the camera
is shaking due to weather, mobile device in motion, etc.
Cameras may be installed in fixed positions or on motorized pan-tilt (PT) platforms, with the cameras fitted
with motorized zoom objective lenses. The PTZ arrangement provides great flexibility in adapting to
varying scene distances and target motions. PTZ control can be exercised manually, from the Security
Operations Center, or can be pre-programmed to “tour” preset positions. For critical monitoring of a single
location consider using a home preset to return a camera to its critical monitoring position if moved
Mount cameras at safe height to prevent damage and provide good field of view. Also if possible, mount
cameras inside secure areas and provide tamper protection if the camera is subject to tamper.
Firm mounting masts are required to prevent motion by wind or pan / tilt unit movement. This is particularly
important for higher power lens used for looking longer distances.
Appropriate camera housings should be provided for worst-case environmental conditions – outdoor, high
temperature, cold, wind, hazardous conditions, etc.
Solid State Video Detectors
Most surveillance cameras employ CCD (charge coupled device) or CMOS (complementary metal oxide
semiconductor) detectors. CCD detectors tend to have better sensitivity but require external support chips,
whereas CMOS detectors tend to have greater dynamic range and are less expensive to manufacture, due
to greater on-chip integration. Both types have a place in airport video surveillance systems and should be
considered during system design.
CCD-equipped video cameras are available which provide nearly full resolution monochrome imagery at
night under conditions approximately equal to full moon illumination without using image intensifier tubes.
This is especially true for airports which are located in or near city centers, where the combination of
exterior lighting and night sky glow enables these cameras to perform at a level acceptable for security
purposes. Dispensing with image intensifier tubes results in better resolution, improved camera reliability,
and lower camera cost.
CMOS-equipped video cameras can exploit the wide dynamic range performance of CMOS detectors to
operate in both high illumination and low illumination conditions that are frequently found at airports. An
example is opening a terminal door from a well-lit interior area onto a dimly lit ramp area.
For a video camera to realize its performance, it must be fitted with a proper objective lens. Target distance,
target size, and the resolution of target details will determine the focal length of a lens. Ambient illumination
will determine the light gathering capability of a lens, as measured by the lens relative aperture (f/#).
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