CCTV System Basics

A basic surveillance system consists of the following:

1. Cameras, lenses, protective housings and mounts.

2. A video processor such as a multiplexer that allows you to record more than one camera at the same time.

3. A recording device such as a time-lapse tape recorder (VCR) or a digital video recorder (DVR). Digital video recorders normally have multiplexers built into the recording unit.

4. One or more video monitors for viewing live or recorded video.

5. Transmission lines such as video coaxial cable and connectors that connect all of the above components together.

6. Power supplies, power cables and a UPS backup power supply that supplies power to the recorder when the electricity is out.

Cameras & Lenses

Cameras range in price from hundreds of dollars to thousands depending on the application. Some types include standard low resolution cameras (low cost), standard medium resolution cameras (moderate cost), Day/Night high resolution cameras that change from color to black and white as the amount of light decreases, Wide Dynamic range cameras that compensate for a wide variety of lighting conditions (especially back-lighting situations) and Dome cameras with pan/tilt and zoom functions. Resolution is a measure of picture quality-the higher the resolution, the better the picture quality.

Lower lighting conditions require more sensitive cameras, faster lenses and possibly infrared (IR) illuminators for nighttime recording in very low to no light conditions. Varying light conditions require auto-iris lenses that automatically adjust for light variations. Auto-iris, aspherical lenses also compensate for the different focal points of color for better picture clarity.

Lighting is Essential

Sufficient indoor and outdoor lighting is crucial for producing high quality video. As light decreases, video becomes “grainy”, the depth of field decreases (the amount of viewing area that remains in focus); and, eventually, the video becomes unusable. More sensitive and wide-dynamic cameras compensate for lower light conditions to some extent, but nothing is better for creating quality video than a well lighted viewing area.

Digital Recorders vs. Time-lapse Tape Recorders

Digital video recorders (DVR’s) are now replacing time-lapse tape recorders (VCR’s) as the standard method of recording and storing video. Video tapes normally need to be changed daily because of the limited storage capability of a video cassette tape, and they need to be replaced regularly due to wear that eventually results in video degradation. The VCR recording heads and belts also wear out every few years, and the entire unit will then need to be replaced.

Digital Video Recorders, on the other hand, record video on hardrives which can store video information for up to 30 days or more depending on the size of the hardrive, the number of cameras being recorded, the resolution desired as well as the number of pictures per second required for a specific application. A casino, for example, would require the highest degree of video quality and pictures per second (real-time video at 30 frames per second). More pictures per second relates to larger video file sizes, larger hardrives and larger, more expensive DVR's.

Remote Viewing/Creating Video CD's/Video Search

Digital Video Recorders can be connected to a network and viewed from individual PC work stations. When connected to a broadband connection, video from the recorder can be viewed from a PC anywhere in the world that has an internet connection with broadband capability.

A built-in CD-R drive on the DVR allows you to burn video clips directly onto a CD that can be played on any PC with a Windows operating system. The CD can then be given to law enforcement as evidence of a criminal act. The video is encrypted and cannot be altered.

Besides being able to store up to a month or more of video, DVR digital video processing allows you to search for a specific time and date as well as a specific viewing area. Searching a video tape from a tape recorder, however, requires hours of tedious rewinding and searching.

Choosing a Camera System

An effective camera system requires professional design and product knowledge in order to produce a quality video recording that will be acceptable in court. A quality video recording requires professional quality equipment.

The smart CCTV shopper will find out what type of CCTV system will accomplish his surveillance goals, and then decide if the cost is within his budget requirements. If you shop for price only, you may be disappointed with the results.