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equipment, storage devices, and auxiliary equipment. servers, cameras, and software algorithms that have been
Generally speaking, most commercially available designed for more commercial applications.
products have been designed to operate in an office type
environment. The harsh environments present within a A. Architecture
substation requires video monitoring equipment that is
significantly more robust and which contains specialized Figure 1 illustrates a typical video monitoring architecture
components that are less susceptible to failure and for electric utilities. It illustrates the most common
which can compensate for less than ideal conditions, to components of a solution and highlights the distributed
ensure that the system remains operational and reliable. nature of the infrastructure. Substations that need to be
In addition, the uncontrolled environments of many sites monitored are generally located in remote areas with
(eg. temperature, EMI, humidity, poor and inconsistent no personnel onsite and many times with only a low
lighting, rain, snow, etc.) make it impractical to utilize video bandwidth channel for communications. This dispersed
infrastructure raises a problem for video streaming.

B. Digital Video Server access control, digital I/O, and SCADA capabilities.
A digital video recorder (DVR) is a device that records video
in a digital format to a disk drive or other medium. DVRs C. Cameras
have become the main way to record video from analog Cameras capture and transmit live images and fall into two
and IP camera as it provides for longer recording times classes, Analog and IP.
than the previously used VCRs. DVRs are typically located Analog cameras are currently the most widely deployed
in close proximity to the cameras as there is generally a video surveillance equipment. They use a CCD or CMOS
direct connection from the camera to DVR. However with image sensor and produce an analog video signal that
the proliferation of IP cameras, a direct connection is no is transmitted through a cable to a subsequent viewing
longer required as video can be transferred over an IP station or other processing equipment. The analog camera
network through switches and routers. Sometimes these is a one directional signal carrier that terminates at a video
types of DVRs are called Network Video Recorders (NVRs).
monitor or recording device. Analog cameras do not allow
remote access, but with the use of video encoders, these
Digital Video Servers (DVSs) are a new class of DVRs cameras can be added to an IP network.
that have all the capabilities of DVRs and NVRs, but they An IP camera captures live video similar to an analog
also make it possible to integrate IP and analog cameras camera, but incorporates the video encoding to transmit
together and can provide additional functionality, such as
INDUSTRY JOURNAL 41