Updated June 25, 2006
Closed Circuit Video Surveillance (CCTV)
Closed Circuit Television (CCTV) has been around for many years, using the old 'Vidicon' image tubes, that produced grainy black and white images, and where very temperature sensitive. Outdoor cameras had to have high power heaters for winter temperatures, and blowers (fans) to attempt to dissipate the heat during the summer from these tube type cameras. The outdoor housings were very large, and required a lot of heavy hardware to move the camera and keep it safe from weather extremes. Look at old buildings with some of the original CCTV equipment and you realize what we are talking about. Many times you would have a $1000 camera housed in Pan-Tilt-Zoom units (PTZ) that cost upwards of $5000.00 and weighed nearly 100 lbs.
With the advent of CCD's (charge-coupled devices) the term used for an electronic light sensor used in digital cameras, the size of cameras began to shrink. As you may know, full color cameras can now be part of a pair of sunglasses, and even smaller.
For commercial applications, the size falls somewhere in the middle…big enough to do the job, and small enough to be unobtrusive.
Another big change has come from the advent of 'Digital' video. That allows video to be recorded as a series of 1's and 0's and stored on a computer type hard drive. The old way was with a "time lapse video tape recorder" with the video tape creeping along in able to get up to 960 hours of recording on a 160 length tape. Most facilities would hook this up to a "multiplexer" that then connects to upwards of 16 different cameras.
Have you ever noticed while watching a replay of some images recorded on a video tape is how the image jumps with a loss of motion, or images that are many seconds apart? It's all a matter of mathematics, and tape speed. Another 'dirty' secret is those time lapse tape recorders need to be cleaned and serviced every 6 months at a minimum. If they aren't, many times the images are unuseable.
(Keep an eye on this page...it's still under construction with a lot of information still being gathered.)
