1) Notes on camera installation positions and orientation.
This section describes precautions designers should bear in mind when installing cameras in one area.
(a) An ultra-wide angle lens is required regardless of the room size when monitoring a whole room.
(b) The use of an ultra-wide lens makes a subject smaller.
(c) Two or more cameras are required to display a subject in a close-up and monitor a whole room.
(d) If space does not permit multiple cameras to be installed, use pan/tilt heads or zoom lenses.
(e) Avoid backlight conditions. (Be aware of windows facing east or west.) When necessary, use cameras that provide backlight compensation such as the Wide Dynamic Range OSD cameras.
(f) When planning a small system, a camera and monitor can be used to select the optimal location for camera placement. There are methods of simulating the picture range to be displayed on the monitor using a PC and the appropriate software such as the TOA CMS software.
2) Installation environments
Following the determination of the camera installation location, take care to completely understand the environment where the cameras are to be installed, then specifically select the necessary equipment. First, select the camera, lens, housing, and motorized pan/tilt head. Conditions that you should know are as shown in Table 2-2.
The camera to be used also needs to be considered depending on the brightness of the subject to be monitored. Monochrome cameras require brightness of at least 100 lux, while color cameras require that of over 300 lux in terms of recommended subject illumination. When wishing to monitor subjects in low light conditions, consider turning on lights or using high-sensitivity or infrared ray cameras. To maintain visibility in smoky conditions, thermal cameras other than the infrared ray cameras can also be used.
(a) High-sensitivity Camera
This camera achieves high sensitivity with minimum subject illumination (0.03lx) by slowing down shutter speed and using signal accumulation. One drawback of this camera is that the signal accumulation method causes a frame-by-frame image advance or lingering afterimage.
(b) Infrared Camera
This camera uses a CCD sensitive to light in the near-infrared region of the spectrum. In surveillance applications, it may be used in conjunction with a near-infrared emitter to enable nighttime surveillance even in pitch darkness. Note, however, that the video images thus produced are monochrome and the range of observation may be limited depending on the near infrared emitter capabilities.
(c) Thermal Camera
This camera uses a CCD sensitive to light in the far-infrared region of the spectrum. It was originally developed for monitoring temperature distribution in medical and research applications. In the past this type of camera was typically expensive and somewhat difficult to handle, particularly due to its cooling components, newer versions that are easier to handle and more economical have lately become commercially available.
4) Temperature and Humidity
The operating temperature range for cameras in general is 14°F to 122°F(-10°C to 50°C). A protective housing will be required for any camera installed in a place where temperatures outside this range are anticipated. Two types of housing are available, one being a simple housing only, the other housing outfitted with temperature-adjustment devices like heaters and/or fans.
Cameras can be equipped to endure even higher temperatures if necessary, by outfitting them with housings incorporating electronic coolers (for ambient temperatures up to 150°F or 70°C) or water coolers (for ambient temperatures up to 212°F or 100°C).
The most hazardous condition affecting camera operation is the formation of dew resulting from rapid increases in relative humidity. Such dew condensation occurs when moisture in the air condenses into water droplets on a solid surface. If this takes place inside the camera or lens, it can cause the metallic parts to rust or corrode, eventually leading to malfunction or early failure of the camera. Consequently, it is necessary to house cameras within a sealed case.
If a camera or its wiring is installed outdoors in a region frequently subject to lightning strikes, steps must be taken to protect the equipment from lightning damage. Protection from direct lightning strikes generally requires large-scale measures like lightning rods, without which it is difficult to counter the risk of damage. However, it is possible to protect the equipment from the lesser hazard of lightning striking the ground in the vicinity by installing a video signal protector. A CCTV system generally requires three different types of
protectors, one each to protect the video signal, power supply, and control signal.
6) Electromagnetic Waves
If cameras are installed under high-voltage power lines or in the vicinity of a broadcasting station, noise may appear on the monitor due to induction. The high frequencies, such as video signals, make it very difficult to eliminate such noise entirely, but some improvement may be gained by using a video transformer. With coaxial-cable superimposition (single-cable) type cameras, however, such a transformer must be of the DC passing type to
allow installation. Another convenient counter-measure is to equip the camera with a grounding wire.
Because most of the CCD elements used in cameras are vulnerable to radiation, cameras installed in nuclear power plants are usually based on image-pickup tubes or incorporate special radiation-resistant CCD’s. In medical radiology labs, CCD cameras can be used because the intensity of the radiation is lower than in nuclear power plants, but they are still affected over time and must be replaced at regular intervals.
In x-ray photography rooms and cobalt treatment rooms, the surface of the camera lens typically discolors brown
over time, blurring the video image, and the camera image itself is affected by white spots that eventually expand to fill the whole screen. Therefore, such cameras are usually installed within a protective housing, the front glass of which is regarded as a consumable part to be replaced as needed.
Protecting cameras against corrosive environments is very difficult. The required measures, such as coating or sealed construction, can be very expensive. If surveillance is required in corrosive environments, the only possible protective measure is to minimize corrosion by choosing the best (minimum exposure) installation placement.
In locations near the seashore, salt-carrying sea breezes are likely to corrode metallic parts.
In swimming pool facilities the culprit is likely to be chlorine vapor rising from the pool water.
Cameras are also vulnerable to corrosive gases including ammonia, hydrochloric acid, sulfur dioxide, hydrogen sulfide, chlorine, fluorine and carbon disulfide. Particular care may be required in factories handling or processing paper pulp, fertilizers, non-ferrous metals,soda, sulfuric acid and synthetic fibers.
9) Explosion-Proof Areas
In operations like petrochemical plants and tunnel-excavation sites where flammable liquids are handled or there is a strong danger of flammable gas leakage, strict regulations are applied to all installed equipment and electrical works. When installing surveillance camera systems in such places, it is absolutely necessary to select camera models with appropriate specifications meeting local legal and regulatory requirements, for example
those with explosion-proof housings.
10) Rain and Dust
The rainproof outdoor housings are used wherever cameras might be exposed to precipitation such as: where water sprinklers are used for cleaning, or where considerable exposure to water droplets is likely (e.g. swimming pools). Similarly, dustproof indoor housings are used in dusty indoor locations, not only for the camera, but also to protect relay boxes and other peripheral equipment.
Depending on ambient temperature and humidity, the front glass panel of the camera casing can become clouded by condensation or frost. Defrosters are available to handle such conditions. Similarly, wipers may be used for surveillance in the rain. Both defrosters and wipers may be turned on and off by the remote controller as needed.