Video Surveillance Glossary of Terms [W - X - Y - Z]

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• » WAN (Wide Area Network) [top]
  A WAN is a communications network serving a geographically large area using satellite communications or telephone lines. The Internet is a WAN.  Network IP Cameras are capable of utilizing WAN systems.
  
• » Wavelength [top]
  Wavelength is how far an electro magnetic wave travels during one cycle.  When discussing DVR, the term refers to the color of light, which every color having a different wavelength.
  
• » Wavelet [top]
  This type of image compression is mainly used for single images and not video streams.  Because it’s superior to JPEG compression, it is however used in some video surveillance codecs, though there isn’t a universally adopted standard for usage of this codec.
  
• » WDM (Wavelength Division Multiplexing) [top]
  This economical procedure enables data from different sources to be simultaneously transmitted over the same fiber optic link.  It achieves this by assigning a unique wavelength to each data channel, resulting in many possible wavelengths traveling across one link, which allows one fiber link to do the same work as two or more.
  
• » Webcam [top]
  Webcams are cameras that connect to the Internet, either via PC or directly, and that allow remote user access.  An IP camera is a popular webcam for video surveillance that does not need a PC connection.
  
• » White balance [top]
  CCD security cameras feature this adjustment to compensate for ambient light color.  Since there’s a color difference between standard light bulb light and sunlight, white balance adjusts to ensure a more realistic picture.  This feature may be set by manual adjustment, or it may have preset settings for the most common situations.
  
• » Wide angle lens [top]
  This lens enables a wide view of the scene, with a magnification ratio less than 1. 
  
• » Wireless [top]
  The wireless transmission of video signals can be carried out over both short and long ranges, with 2.4 to 5 GHz devices for short distances and high-power line dedicated site solutions for several miles or more.
  
• » Y/C [top]
  Occasionally known as s-video, this video signal splits chrominance (c) and luminance (y) onto two separate signal wires for better composite video picture quality.
  
• » YIQ (Luminance In-Phase Quadrature) [top]
  The color space used in NTSC is called the YIQ. 
  
• » YUV (Luminance Chrominance) [top]
  YUV is the color space used in PAL, and is preferred for video signals.  YUV and RGB can be converted back and forth. 
  
• » Zoom lens [top]
  A zoom lens has the advantage of offering a variable focal length to view both wide angle to telephoto scenes.
  
• » Zoom ratio [top]
  This measures the ratio between the maximum and minimum focal length that a zoom length is capable of.

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