CCTV System Basics
A basic surveillance system consists of the following:
||Cameras, lenses, protective housings and mounts.
||A video processor such as a multiplexer that allows you to record more than one camera at the same time.
||A recording device such as a digital video recorder. Digital Video Recorders have multiplexers built into the recording unit.
||One or more video monitors for viewing live or recorded video.
||Transmission lines such as coaxial cable and connectors that connect all of the above components together.
||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 low resolution indoor cameras with fixed lenses (low cost), high resolution cameras, outdoor 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), cameras with built in infrared illuminators that see in complete darkness, vandal-resistant cameras, Dome cameras with pan/tilt and zoom functions and a variety of specialty, high end cameras.
Lower lighting conditions require more sensitive cameras, faster lenses and possibly infrared illuminators for nighttime recording in very low to no light conditions. Varying light conditions require auto-iris lenses that automatically adjust for light variations. Aspherical lenses compensate for focal aberrations 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 infrared cameras compensate for lower light conditions to some extent, but nothing is better for creating quality video than a well lighted viewing area.
Scene Detail and Facial Recognition
If facial identification is required, then more cameras are needed to cover a specific area for greater detail as compared to one camera with a wide angle lens covering a larger area with less detail. A common error in designing an effective CCTV system is not using enough quality cameras to produce a quality video recording that would be acceptable in court.
The camera image in fig. 1a and the enlarged view in fig. 1b would be more acceptable for indentification than figures 1c and 1d.
Digital Video Recorders record video on hard drives which can store video information for up to 30 days or more depending on the size of the hard drive, the number of cameras being recorded, the resolution desired as well as the number of frames per second required for a specific application.
A casino, for example, would require the highest degree of video quality and frames per second (real-time video at 30 frames per second). Recording more frames per second produces more fluid motion pictures (video) and requires larger video files, larger hard drives and larger, more expensive Digital Video Recorders.
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, DVD drive or USB port on the DVR allows you to burn video clips directly onto a disk or drive that can be played on any PC with a windows operating system. The disk can be given to law enforcement as evidence of a criminal act. The video is encrypted and cannot be altered.
DVR digital video processing allows you to search for video by time and date, by motion or alarm event, and in some models, by a specific area within a scene.
REACTIVE monitoring or video verification service is available when your CCTV is connected to the internet. If our Central Station receives an alarm signal from your building security system, the operator can bring up the video and provide the Police with specific details and descriptions of the crime in real time.
PROACTIVE monitoring is based on a specific look-in schedule to replace or augment security guard or drive-by patrols.
Home surveillance systems may consist of a stand-alone system that uses a separate video monitor or an integrated system that is connected to your home TV system using a modulation device. Connecting to just one existing TV eliminates the need for a modulation device, a separate video monitor and additional wiring.
Residential cameras and housings are usually smaller and more discreet than their commercial counterparts.
a Camera System
An effective camera system requires professional design and product knowledge in order to produce a quality video recording that would be useful to law enforcement and acceptable in court. A quality video recording requires professional quality equipment. If you shop for price only, you may be disappointed by the results.