CCTV Surveillance & Types
Closed-circuit television (CCTV), also known as video Surveillance, is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly transmitted, though it may employ point to point (P2P), point to multipoint (P2MP), or mesh wireless links. Though almost all video cameras fit this definition, the term is most often applied to those used for Surveillance in areas that may need monitoring such as banks, schools, airports, hospitals, military installations, and convenience stores. Videotelephony is seldom called "CCTV" but the use of video in distance education, where it is an important tool, is often so called.
In industrial plants, CCTV equipment may be used to observe parts of a process from a central control room, for example when the environment is not suitable for humans. CCTV systems may operate continuously or only as required to monitor a particular event. A more advanced form of CCTV, utilizing digital video recorders, (DVRs), provides recording for possibly many years, with a variety of quality and performance options and extra features (such as motion detection and email alerts). More recently, decentralized IP cameras, some equipped with megapixel sensors, support recording directly to network-attached storage devices, or internal flash for completely stand-alone operation. Surveillance of the public using CCTV is particularly common in many areas around the world. In recent years, the use of body worn video cameras has been introduced as a new form of Surveillance.
Chip Sets
The two most common security camera types are CMOS, which stands for Complementary Metal Oxide Semiconductor, and CCD, or Charge Couple Device. Both types capture images using computer chips measuring 1/4, 1/3 or 1/2 inches. In general, larger chip sizes produce better image quality, with 1/3-inch chips serving as the industry standard.
Lens
A security camera's lens determines the overall Surveillance field. Larger lenses provide a narrower, more zoomed field of view, while smaller lenses offer a wider perspective. Typical lens sizes range from 3.6 mm to 18 mm. Lenses also come in either fixed or variable focal length and may be designed to work in low-light conditions.
Resolution
A security camera's resolution indicates the captured image's detail level; cameras with high resolutions produce crisper, cleaner images. Manufacturers typically measure security camera resolution in TVL, which represents the number of horizontal TV lines. TVL provides a more accurate depiction of a camera's resolution.
Wired vs. Wireless
Security cameras come in either wired or wireless models. Wired cameras are the most cost effective and also offer the best, most reliable video quality, because there is never a problem with signal interference.
Colour vs. B&W
Continued technological advances have made colour security cameras far more affordable, positioning them as viable rivals to traditional black-and-white security cameras.
PZT
Law enforcement operations and high-risk environments such as casinos typically employ PZT cameras, which stands for Pan/Zoom/Tilt. These advanced features allow for greater visual coverage and enhanced image detail.