CCTV or Closed Circuit Television refers to a visible or covert video system intended for only a limited number of viewers. In Closed Circuit TV (CCTV),
the picture is viewed or recorded, but not broadcast. It was initially
developed as a means of security for banks and casinos; however, today
it has been developed to the point where it is simple and inexpensive
enough to be used with Home Security Systems, and for everyday surveillance.
More specifically, CCTV is a television transmission system in which live or prerecorded
signals are sent over a closed loop to a finite and predetermined group
of receivers, usually as scrambled radio waves that are unscrambled at
the point of reception. CCTV takes numerous forms and performs a wide range of functions ranging
from image enhancement for the partially sighted to the transmission of
pay-per-view broadcasts. Although cable television is technically a
form of Closed Circuit TV,
the term is generally used to describe systems with more specialized
applications than a standard broadcast or cable television. Such
specialized systems are not subject to regulation by the Federal
Communications Commission (FCC); however, Security Cameras using scrambled radio waves are in fact subject to common carrier tariffs and FCC conditions of service.
CCTV is most commonly used for surveillance. Security Cameras are now universally featured in many public and private institutions,
from a correctional facility to the convenience store. In prisons, reduce the costs of staffing and operating observation towers and make
it possible to maintain a constant watch on all areas of the facility.
CCTV has become so much less expensive over the years that both large
and small stores are able to install cameras as a deterrent against
theft and robbery, a practice, which municipal authorities have adopted
as a way of curtailing crime in public housing and even on city
streets. In many areas of the country as well as in Europe, Security Cameras have been placed in highly crowded public areas as a security measure against terrorism.
CCTV has many industrial and scientific applications outside of the
world of surveillance. Electron microscopy, medical imaging and
robotics are all common uses of CCTV, however, the term "Closed Circuit TV" does in fact most often refer to security and surveillance camera systems. Other common forms of CCTV include live on-site video displays for special events such as various
conventions, arena sports and concerts as well as pay-per-view
telecasts of sporting events such as boxing and pro wrestling. Also a
common user of CCTV is "in-house" television channels that broadcast to very small and
specific receivers such as in hospitals, airports, racetracks, schools,
malls, grocery stores, and municipal buildings.
In-Line: These are the most simple model and thought of as the traditional CCTV. The monitor or video display is mounted over the camera.
Out-of-Line: These models have a camera unit and
generally use a television as their display. They are not "portable" in
the sense that the camera unit is a full size camera and the devices
should be used on a desk. The camera unit would sit beside the monitor,
or "out of line."
CCTV's that use Computer Monitors: These CCTV’s
connect simply to a computer monitor. They are not interchangeable with
a television, but are made specifically for integration with a monitor.
They offer access to the print material, the computer application, or
both using a split screen function.
Portable: These CCTV’s can be considered portable in that you do not have to use a television
with them. You can purchase a display that will allow you more freedom
in how it is used.
Hand Held: A Hand Held CCTV is not always portable. Most models depend on the use of a television
unlike the purely portable CCTV’s. Generally, the ability to write
using a hand held or Portable CCTV is not as functional as with In-Line or Out-of-Line models.
There are four types of lenses for CCTV use:
Fixed Aperture, Manual Iris, Auto Iris, and Zoom. If the area you wish
to observe experiences infrequent changes in light, use a manual iris
lens, which can be adjusted for light only by hand. If the area the Security Camera will be observing experiences frequent changes in light, use an
auto-iris lens. These lenses adjust to light changes automatically.
Auto-iris lenses come in Video or DC, and cameras generally support one
format or the other. Be sure your lens matches the camera. To perform
close-ups, get a zoom lens, manual and motorized zoom lenses are easily
available from most retailers.
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