CCTV Solutions

There are several reasons why a retailer might want to install CCTV, one reason is to capture shoplifters red-handed, but also an increasing reality in the retail industry is combating staff theft. Cameras can be placed around tills, stock rooms and staff exits in order to monitor the activities of retail staff.

ADT specialises in providing CCTV systems which meet the requirements of a variety of property types, such as retail premises, educational establishments, industrial sites and offices. CCTV can be simple or complex, for example to identify individuals or vehicles, to alert an operator to the presence of an individual or to visually patrol a pre-defined area. Once objectives have been agreed, an appropriate mix of system components can be recommended.

How do you know your Needs?

Surveillance-cameras: this article will show you the importance of selecting your surveillance camera according to the use to which you want to put your system, without spending a fortune in the process.

Surveillance-cameras have the task of capturing images by transforming the visible scene observed by a Camera Lens and projected upon an imager or Camera Sensor, into an electric signal to be further processed.

Surveillance cameras perform their function mostly unattended. That is why they should be selected so that their images are understood and useful most of times, even when no operator is there to optimize the viewing parameters.

For an informed decision when choosing from Surveillance-cameras the equipment for your CCTV video system you have to take into account a few considerations:

• The task that Surveillance-cameras systems are intended to perform (detection, assessment, alarm, identification, documentation).
• The overall characteristics of the system you specify according to the actual application (space to observe, details, sensitivity).
  See Fundamental Concepts.
• The light available at the selected location, its amount and variability.
• The environment, exposed or protected.
• The cost.

Conciderations

To consider the alternatives of the different types of Surveillance-cameras, you should examine the characteristics as follows:

1. Color vs. Black & White
2. Outdoor vs. Indoor environment
3. Fixed vs. PTZ
4. Dome vs. Bullet

Color vs. Black & White (Monochrome)

The amount of light available at any time on the scene, and its constancy in time will influence the choice of Black and White vs. Color.
Color Surveillance-cameras generally require a higher level of lighting than black & white.

Color produces a more natural, richer image than black & white. If the scene has to be monitored constantly, color may keep the observer's attention for longer periods of time. It may also make it easier to detect suspect persons. With a color system a viewer can easily distinguish colors, while on a black & white system any color would appear a similar shade of gray.

While the use of color cameras is growing, black & white Surveillance-cameras continue to offer some unique advantages because they are better suited for extremely low light situations and for IR (Infrared) illuminated scenes. At low illumination levels most color images look anyway like black & white on monitors.

Capturing good quality images in low light increases the cost of both black & white and color Surveillance-cameras. It is possible, and has to be determined, if low-light cameras (that is with increased sensitivity, lower lux rating) will cost less than the expense to increase and maintain lighting.

Day/Night color Surveillance-cameras are available that see colors during the day in full light, but switch to black and white for clearer pictures after dark.

Environment

It is quite sure that indoors applications poses to the Surveillance-cameras a much more friendly environment that what is likely to be found outdoor.

Given the object and the purpose of the surveillance one should select the most suitable equipment (Outdoor vs. Indoor). It is recommended to consider the options before performing the final selection.

For outdoors applications, Surveillance-cameras come with a more durable and watertight housing, usually sufficient for light rain, although not waterproof if immersed.

Outdoor Surveillance-cameras are designed to keep the camera's parts at an optimal temperature in outdoor weather conditions. If in a certain location environmental conditions may be occasionally extreme, provisions like internally mounted heaters and blowers can be selected to guarantee continuous operation.

For applications in conditions of high humidity, completely sealed cases may be needed to avoid condensation inside the camera at low temperatures.

In regions frequently subjected to lightning, the protection of properly installed nearby lightning rod should be assured.

Furthermore additional protectors should be selected for power supply and video signal cable. A grounding cable should be provided to the camera.

For interior use, cameras are more aesthetic, less protected. Even if in full view, cameras may match the interior decor without being unduly coarse.

Fixed vs. PTZ

A camera can be fixed in space so that its field of view is not going to change. This will probably be the case for most of home surveillance cameras except for those continuously monitored by operators.

Alternatively the camera may be given the motorized capability to pan (move from side to side to cover a panorama) to tilt (to search from floor to ceiling), and to zoom in (to enlarge the image and reduce the field of view) or zoom out (to reduce the image and enlarge the field of view) from near to far.

This faculty, called PTZ (Pan-Tilt-Zoom), needs be commanded by an operator with a joystick or through mouse and software in a PC based system. This is not normally the case for home security applications where the camera has to work unattended.

In principle PTZ Cameras can be programmed to run automatically through predetermined movements or be auto commanded if the system detects motion or if an alarm condition is determined.

However, given the complexity of the system, it could be considered for home surveillance only if a setup of a few fixed cameras (preferable) would not achieve the same effect at the same or lower price than the complex solution.

It is strongly suggested to avoid assuming that a single camera can perform spatial surveillance of a large space. That could better be performed by two or more dedicated cameras, each one centering on a spot of interest.

Dome vs. Bullet

Regular cameras come full size like a short tube (bullet), a cylindrical body, or a square section box. They may be either exposed or protected in a dark dome or a mirrored finish (which reduces some of the illumination and distorts color accuracy), or an elongated body dome to hide the real line of observation. For use in extreme low light conditions, a series of infrared lamps may surround the lens. See hereafter additional considerations.

Many PTZ cameras today are disguised in dark colored plexiglas housings called domes. Dome cameras are found practically everywhere. They are particularly popular wherever aesthetics are important.

The benefits of dome cameras are:
Deterrence: Domes in full view conceal where the camera inside it is pointed. Whoever sees the dome cannot know whether or not he/she is under surveillance.

Aesthetic appearance: A dome makes the collection of equipment more aesthetically acceptable, and does not detract from the interior design.

Mount

For installing Surveillance-cameras a suitable mount should be selected. Depending on the location fixing the mount to a wall, to the ceiling or to a pole may be most suitable. In general the camera should not be accessible without a ladder or a construction.

This is to avoid interference or sabotage or even remotion. If the selected camera has to be fixed in position, the mount should permit easy orientation and final permanent set.

Power

The usual power supply for most of the surveillance cameras is a simple adapter (transformer) providing 24 Volts of alternating current. It may be included in the package or else it may need separate purchase.

For multiple camera setups, depending on outlet locations, it may be more economic to procure a central adequate power supply with individual wires to the different cameras. In any case the power supply has to be plugged in a normal household outlet with a power cord of about 2 m (6 ft).

If the camera is placed far from available current taps but no more than 100 m (350 ft.), a pair of low voltage (24 V) power wires (speaker wire, 18 or 20 gage) is all that is needed.

Surveillance-cameras can be obtained plugging directly in house AC (alternating current) mains outlets (120 V in the USA, 220 V in Europe). If not readily available near the camera location, long lines may need to be laid down, which is probably a disadvantage.

Other Surveillance-cameras work with 12 Volt of direct current. They could receive their power supply from large batteries. This can be useful, especially for a car installation. Otherwise there would be a continuous need of substituting spent batteries with new ones. (Note: Four AA batteries providing 6 V, doubled internally by the supplier, would last for about four hours).

This solution cannot be used with long lines because of voltage drop. Also for multiple cameras it is not recommended because of the lack of synchronizing signals from the power supply. In case of alternating current power supply there is an integral signal used for synchronization with the mains frequency.

Coaxial cables (for video transmission) are available with power wires embedded in the insulation. Another combination system exists that lets the video signal and the power supply run on the same coaxial cable, especially convenient if the camera is to be driven from a central location. This solution may have some merits in certain situations, but it is definitely discouraged for simple do-it-yourself applications.