CCTV Security Cameras (Analog Cameras)

A CCTV camera transmits its video over coaxial cable using an analog composite video signal.  An analog color video signal contains luminance, brightness (Y) and chrominance (C) of an analog television image.  CCTV cameras still make up the majority of the security cameras used today.

 

Advantages

  • Cameras use industry standard coax cable (RG59 or RG6)
  • Cameras can transmit video using baluns over UTP cable (Cat5 or Cat6)
  • Power is carried over a Siamese pair of wires
  • CCTV technology is very inexpensive compared to IP security technology
  • Video can be transmitted over 1500ft. of cable
  • Large variety of cameras to choose from

 

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TV Lines

Resolution of CCTV security cameras is measured primarily in TVL (TV Lines).  TVL is the number of horizontal lines.  The higher the number of TV lines a camera can produce, the better the quality of image the camera can potentially produce.  TVL is an analog CCTV specification and cannot be directly translated to pixel resolution like IP cameras.  Ten years ago the standard was 400TVL – today the standard is between 700TVL and 1000TVL for CCTV installations.

 

CCTV Digital Recording Resolutions

Digital video recorders capture the CCTV image and digitizes it for live display and recoding.  Its capture and recording capabilities are measured in CIF (Common Intermediate Format).  CIF was part of the H.261 standard format used to standardize the horizontal and vertical resolutions in pixels of YCbCr sequences in video signals.  The most commonly used CIF resolutions are:

  • QCIF – 176 x 144 (0.02 Megapixel)
  • CIF – 352 x 240 (0.1 Megapixel)
  • 2CIF – 704 x 240 (0.17 Megapixel)
  • 4CIF – 704 x 480 (0.3 Megapixel)
  • D1 – 702 x 480 (0.3 Megapixel)

 

 

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Form Factors

CCTV cameras come in a variety of form factors. Which form factor to use depends on several circumstances including desired image quality, aesthetic requirements, desire for conspicuousness, vandalism potential and camera features. The most common form factors include:

  • MiniDome
  • Dome or Surface Dome
  • Turret Dome
  • Recessed Ceiling Mount
  • Bullet
  • Mini-Bullet
  • Recessed Wall Mount
  • Box
  • C-Mount
  • Semi-Recessed
  • Pan-Tilt-Zoom Dome (PTZ)
  • Enclosed Box
  • Covert (Hidden camera – takes on various form factors)


Camera Features

Each camera model has its own unique feature-set. Each feature is important in deciding which camera you require and depends on many factors including lighting conditions, object distance or mounted height of camera, desired image clarity, weather conditions for outdoor cameras, vandalism potential and accessibility.

 

Varifocal Lens

Some security cameras offer varifocal lenses. A varifocal lens is a camera lens with variable focal length (magnification). Varifocal lenses come in different magnification varieties. The numbers associated with the lens coincides with the amount of lens magnification. A typical varifocal lens might have a focal range of 2.8-12mm. The higher the number, the greater the magnification. The same type of lens formulas used for photography apply for security cameras.

 

Auto Focus

Autofocus is the ability for the camera to automatically adjust its own focus. This is done with a tiny motor attached to the lens and the camera uses an algorithm to determine when the focus is correct. Autofocus cameras are necessary for environments where cameras are difficult to access or where perfect focus is critical. The auto-focus feature on a security camera is generally a costly feature adding between 60 and 300 percent to the cost over manual focus cameras.

 

widedynamicrange

 

WDR (Wide Dynamic Range)

Most modern cameras come equipped with WDR (Wide Dynamic Range). Wide dynamic range is the ability to handle a wide range of lighting conditions within a single scene. For instance, the sunlight shining through the windows or glass door from inside a building would distort a camera view without WDR. WDR has the ability to filter out the various lighting conditions so that the image remains clear and consistently visible.

 

BLC (Backlight Compensation)

Most modern cameras are also equipped with BLC (Back Light Compensation). BLC works well in conjunction with WDR. BLC has a similar objective to WDR but is handled in a different way by the camera. Where a bright light source is behind the subject of interest, the subject would normally appear in silhouette. BLC adjusts the exposure of the entire image to properly expose the subject in the foreground.

 

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IR (Infrared) Illumination or Night-vision

Some cameras are equipped with IR illumination which gives the camera the ability to see in the dark. In complete darkness, the infrared light reflects back off objects giving the camera the ability to see without any visible light. IR illumination ranges in power (brightness), distance and angle.

 

Power Options

CCTV cameras are powered using either 12VDC or 24VAC.  Some cameras can support either voltage input (dual voltage camera).  12VDC is used most frequently, however 24VAC is required when cable runs are longer to compensate for voltage drop.

 

Vandal Resistance

In environments where vandalism might be an issue, a vandal resistant camera can be used. Vandal resistant cameras are made especially touch to resist vandalism attempts. Vandal-resistant or vandal-proof domes are with a special clear or smoke plastic that can withstand a hit from a blunt object. Vandal Resistance is measured in an IK index, an IK10 being the highest.

IK rate IK01 IK02 IK03 IK04 IK05 IK06 IK07 IK08 IK09 IK10
Energy at the impact (Joule) 0.14 0.2 0.35 0.5 0.7 1 2 5 10 20
Mass (Kg) 0.25 0.25 0.25 0.25 0.25 0.25 0.5 1.7 5 5
Stroke down (mm) 56 80 140 200 280 400 400 300 200 400

 

Operating Conditions

Cameras are manufactured for a specific operating condition range in temperature and humidity. Environments with higher temperatures and/or high humidity require cameras made to survive these environments. Especially cold environments also require specially made cameras.

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Evyn Security offers sales, service, installation and support for video surveillance, access control and alarm systems throughout northeastern Ohio including Cleveland, Lorain, Media, Sandusky, Akron and Canton. Our mission is to provide our customers with the best possible value in security products and services with a perfect balance of quality and price.

 

 

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