With IP cameras transmission is accomplished through unshielded, twisted-
pair cabling as part of a structured telecommunications cabling system. Fiber
optic cable is utilized for exceptionally long cable runs or for exterior cameras
where lighting protection is a concern. The distance between the camera and
the headend equipment, as well as cost, security of signal, and resolution,
may be considered in selecting the physical transmission media.
Wireless transmission can be used for cameras where cable is impractical or
costly. Wireless can be deployed rapidly but it may require power and line of
sight between locations; it may also be susceptible to interference. Wireless
technologies include “Wi-Fi,” infrared, microwave and free-span optic (FSO)
systems.
Video Processing
Video processing codes or encrypts video signals from surveillance cameras.
The processing allows multiple cameras to be displayed on a single monitor
or multiple camera views to be cycled on a monitor. Two products, both of
which are remnants of analog video systems, have typically been used to
accomplish this: a cross-point matrix and multiplexer.
The basic functionality of the older cross-point matrix is to switch
camera feeds to different outputs. It takes the feeds or inputs from the video
surveillance cameras and “binds” any input to any output or to multiple
outputs.
Older video multiplexer functionality can be summarized as taking multiple
video feeds and combining them into a single video feed. This allows multiple
cameras to be viewed on a single monitor. Multiplexing does so by lowering
the resolution of each video feed and rescaling it to a screen, typically showing
the views of 4, 9, or 16 cameras.
In a digital system with IP cameras and a network server replicating a cross-
matrix and multiplexer functionality is significantly enhanced through a soft-
ware-dependent approach rather than the hardware-dependent approach of
traditional analog systems.
Recording
One of the first components of video surveillance systems to go digital was the
digital video recorder (DVR) introduced to replace the older, tape-based video
cassette recorder (VCR). The VCR worked with analog video and typically
86 Smart Building Systems for Architects, Owners, and Builders