You've probably seen CCTV footage on the news or on America's Most Wanted-those crime scene videos that detectives use to identify and prosecute the culprits. CCTV (Closed Circuit Television)-a system of surveillance cameras hooked up to a monitor for security personnel to see-has long been a popular way to monitor banks, government facilities, shopping malls, and other public areas.
These days, CCTV systems are common enough-and affordable enough-that people have even begun to use them for private homes. Conventional CCTV systems have always used analog recording, where the footage is caught on tape with a VCR. Over the last several years, however, CCTV has been moving steadily towards digital. Digital cameras provide higher-resolution pictures than analog cameras and allow you to access them quickly and easily from any PC. There are two types of digital surveillance technology: digital video (DV), and closed circuit digital photography (CCDP).
DV-type surveillance is the type of digital CCTV most commonly in use. Digital video cameras record images in digital format, via either a digital video recorder (DVR) or a PC-based DV capture card. DVRs are basically digital VCRs-they receive and store the recorded material in digital format so you can send it to a PC. PC-based DV capture cards plug into the computer and compress the DV signal at the PC level-that is, the images go straight from the camera to the computer via the card. Many digital security cameras also have motion detectors, which means they only send images when something in the area moves.
While digital video has better resolution than analog video feeds, the various compression and/or file-conversion processes that the images have to go through to get to the monitor do take a toll on the final product-so although you're a step ahead of analog, the quality of digital videos is still fairly poor.
Closed circuit digital photography, or CCDP, is a new surveillance method that sends digital stills, taken on either a time-lapse or motion-detection basis, to your PC. Because still pictures are smaller than video files, they don't need to be compressed, so CCDP images have a higher resolution than DV images. This is helpful when you need to see specific details, such as facial features or lettering. Unlike DV systems, though, CCDP cameras aren't very effective for showing live video feeds; their main advantage lies in the quality of the images. In places that require continuous live monitoring-i.e., where a quick response makes a big difference-you're probably better off with a regular CCTV system. In places that don't need round-the-clock surveillance, though-private homes, for instance-a CCDP system gives you a sharper picture.
What to Look For in a Digital Surveillance Camera
Once you've decided which type of digital surveillance system best fits your needs, you need to decide on a camera. Here are a few things to consider when buying a digital security camera:
- Location. Where do you need to put the cameras? You may need more or fewer of them depending upon the size of the area and how much of it needs surveillance. Also, if it's outdoors or in an area with low lighting, you may want to invest in a day/night or infrared-sensitive camera.
- Focal length. How far away will the camera be from the target area? This will affect your choice of zoom lens.
- Field of view. You may want a narrower- or wider-angle lens depending on how much area you want to cover.
- Resolution. As mentioned before, some cameras produce clearer images than others. High-resolution pictures with greater detail may be a priority for you.
- Price. How much are you willing to spend? Higher-resolution cameras with advanced security features tend to cost more. Decide which features are important to you and shop accordingly.
One way or another, a security camera in plain view can be an effective deterrent for a burglar; chances are, burglars won't break in if they know they're being watched. Just in case, though, you want to make sure your digital camera is top notch, so if someone does break in, you know you've got them covered.