The ABC's of CCTV    

 

The following "How To" guide is designed to help less experienced CCTV dealers become accustomed to basic systems design. However, always remember, the "Helpful and knowledgeable" staff at , Inc. is always just a toll free call away!

 

WHAT GOOD IS IT?

 

Advances in CCTV technology are turning video surveillance into one of the most valuable loss prevention, safety/security and management tools available today. Retailers use CCTV to monitor for shoplifters and dishonest employees, compile recorded evidence against bogus accident claims and monitor merchandising displays in stores that may be hundreds of miles away. Manufacturers, governments, hospitals and universities use CCTV to identify visitors and employees, monitor hazardous work areas, thwart theft and ensure the security of their premises and parking facilities. New opportunities for CCTV are growing as fast as the technology and security environments are phenomenal.

 

Security Applications:

 

Observe and record theft or violence by overtly monitoring retail floor space, office

buildings,

building perimeters, warehouses, loading docks, and parking garages.

Monitor sensitive areas, where infrequent activities, occur {i.e. confidential records, safes,

ect.)..)..)..)..)..).

Monitor point‑of‑sale exceptions {cash register voids, over‑rings, ect.)..)..)..)..)..) to reduce

cashier theft

Observe and record shoplifting activities.

"Walk a beat" by programming a moving camera to pan, tilt, and zoom within a defined

pattern.

Perform covert surveillance Where legally applicable).

Integrate with access control systems to provide video of persons entering and leaving the

premises

Complement asset tracking systems to provide video when a tagged asset leaves the

premises.

 

Safety Applications:

 

· Allow operators to see into areas where the environment is hazardous to life or health {i.e. hazardous materials, chemical toxins, ect.)..)..)..)..).).

 

· Monitor potential accident areas.

 

· Monitor residence halls, common areas, or high‑risk areas to ensure safety of an educational institution's students and faculty.

 

· Help reduce the severity of some incidents by the timely dispatch of security, police, fire and emergency medical personnel.

 

Management Tool:

 

· Train employees, check stock on store shelves and monitor retail sales floor coverage, production lines, ect.)..)..)..)..)..

 

· Demonstrate management's due diligence towards protecting employees, clients, and visitors, and perhaps avert or minimize litigation and negative publicity.

 

· Document video images on magnetic tape or optical hard discs to record events. This information may be reviewed and later presented as evidence for prosecution of criminals, or as a training tool.

 

When integrated with access control, asset tracking, fire systems and other life safety and security measures, CCTV's "silent witness" provides an additional advantage: the ability to see and review the impact of these systems on people and property.

 

 

 

LETS GET STARTED

 

Many elements must be considered when designing/installing a CCTV system.

 

1.

 

2. 3. 4. 5. 6.

 

Scene and lighting

The cameras

The lens

Video transmissions

methods

The monitor

Peripheral equipment

 

The Scene and

Light

 

The scene refers to the objects or area to be observed and the total environment in which they exist.

 

A scene often contains different colors, surfaces and materials that reflect varying levels of light. To select proper equipment, it is necessary to determine the minimum lighting level (day or night) that will arrive from the scene to the camera lens. The "available" light will affect everything from picture clarity to focus (see figure 1).

 

A scene or target area can be illuminated by natural or artificial light sources. Natural sources include the sun, the moon and stars. Artificial sources include incandescent, sodium, fluorescent, infrared, and other man‑made lights. An axiom in CCTV security applications is: The better the light, the better the picture.

 

Figure 1. Cameras respond the amount of light reflected from the scene

 

Color vs. Black &

White

 

Color cameras generally require a higher level of lighting than their monochrome {black & whited counterparts.

 

Color produces a more natural, richer image than black & white and may keep the operators' interest for longer periods of time. It also makes it easier to detect subjects. For example, with a color system a viewer can easily distinguish a red car from a green one, while on a black & white system both cars would appear a similar shade of gray. In retail applications, a color system can help security personnel identify shoplifters and their clothing more easily and convincingly. Color accuracy is extremely important in gambling casinos, where hundreds of dollars can ride on the ability to recognize the difference between a maroon chip and a red one.

 

( wearing ) red??

 

 .

 

 

 

 

While the use of color cameras is growing, black & white cameras continue to offer some distinct advantages. Black & white cameras are better suited for extremely low light situations.

 

The ability to capture good quality images in low light situations increases the cost of both black & white and color cameras. Before purchasing cameras, organizations should consider the crossover point between lighting costs and camera costs. It's possible that low‑light cameras (which are expensive) will cost less than paying to increase the lighting in a parking lot.

 

The Camera

 

Cameras convert the visible scene captured by a lens into an electric signal and transmit that signal to a monitor for viewing

 

Several considerations should be taken into account when choosing the proper camera/lens for any video system:

 

The purpose of the video system (detection, assessment, identification, ect.)..)..)..).

 

· The overall sensitivity of the camera needed based upon the actual application.

 

· The amount and varying levels of light available at the scene.

 

The environment in which the camera will operate (indoors/outdoors).

 

· The f

 

The lens

 

· Cost.

 

of view (((FOV))) required by the application (see figure 3).

 

Monitor

 

~ F.O.V.

 

Figure 3. Field of view.

 

Camera performance depends largely upon the reflected light at the scene and the quality of the cameras imager (see figure 4).

 

Where the level of available light can change dramatically, a camera equipped with automatic iris control can help assure consistent image quality. Automatic iris control enables cameras to open or close an auto iris lens to adjust the amount of light passing through the lens. On a bright, sunny day, for example, an auto iris camera will close the lens' iris to prevent strong light from reaching the camera's imager. At night, the camera will open the iris to allow a greater amount of light into the camera.

 

Cameras are available in various "formats" expressed as' 1/2,, 1/3, or /4 inches. These measurements represent the overall usable size of the camera's imager. In general, you should match the camera's format to the lens format. For example, a half‑inch camera should be paired with a half‑inch lens.

 

 

 

Today, thanks to design improvements, high quality images are possible with smaller formats.

 

Figure 4. The imager (or chip ).

 

Fixed and PTZ Cameras

 

CCTV cameras can be fixed or have pan, tilt and zoom ((PTZ)) capability. Fixed cameras are mounted on a fixed bracket and cannot move in response to operator commands. PTZ cameras are motor driven and can pan left and right, tilt up and down and zoom in and out for close‑up or wide‑angle viewing. (See figure 5)

 

Pan

 

Tilt

 

Scan

 

Figure 5. PTZ camera.

 

A cameras housing protects the camera and lens from vandalism and the environment. It also can enhance the appearance of the camera installation and conceal the equipment from casual observation. All outdoor cameras require a housing of some type. The National Electrical Manufacturers Association (((NEMA))) rates housings on their ability to withstand environmental conditions. Protection from cold, heat, dust, dirt or other elements is needed to ensure optimum performance and extend the life of the camera.

 

Dome Cameras

 

Many PTZ cameras today are disguised in dark colored Plexiglas housings called domes. Dome cameras are found practically every major department store and in many industrial/commercial locations, hospital, colleges and government facilities (See figure 6). They are particularly popular wherever aesthetics are valued.

 

 

 

Dome cameras provide three primary benefits:

 

1. DETERRENCE ‑ Domes make it virtually impossible for suspects to determine where the camera is pointed. individuals planning to commit criminal activity are unable to detect whether or not they are under active surveillance.

 

2. ECONOMY ‑ Domes equipped with a camera, lens, and pan/tilt unit can be augmented with "drones" that have the same outward appearance, but have no equipment inside. The result is more apparent camera coverage with a much lower system expense.

 

3. AESTHETIC APPEARANCE ‑ An exposed camera, lens, pan/tilt unit and associated wires are unsightly. A dome makes the collection of equipment more aesthetically acceptable, and does not detract from the interior design of a retail or business office environment.

 

Placing a mirrored finished or smoked bubble around the dome con conceal a dome camera further. However, when this is done, the bubble has the effect of sunglasses, reducing the amount of light reaching the lens and affecting the color accuracy picked up by the camera.

 

(Indoor. ceiling mount)                

 

Optional plexiglass bubble

 

(Outdoor mount with  clear bubble)

 

Figure 6. Dome cameras.

 

The Lens

 

Lenses (Optics} play an important role in the design of a CCTV system. Their primary function is to collect reflected light from a scene and focus a clear, sharp image on the camera's imager. Typically, the more light that passes through a lens, the better the quality of the picture.

 

Selection of a lens is especially critical because it directly affects the size, shape, and sharpness of the image to be displayed on the imager. Factors such as distance from the scene, focal length, desired field of view, lighting and format affect the size and clarity of the image on the camera's imager.

 

Field of View

 

The field of view ((FOV)) is the actual picture size (height and width) produced by a specific lens. field of view is not suitable, you may consider using a different lens (wide angle, telephoto, etc.) to increase or decrease the field of view. Tables are available to calculate the proper imager size, lens and distance combination needed to produce a desired field of view. See page 92 of this catalog.