In this day and age, most people are very familiar with Video Surveillance systems. From small two and four camera systems used to monitor homes and convenience stores to gigantic systems with hundreds and perhaps thousands of cameras, the use of video surveillance is increasing daily. Some studies have shown that an average person will be recorded on a video surveillance system at least four times every day.

So you want to install your own Video Surveillance System? Ten years ago, I would have never supported the idea, but recent innovations in Video Surveillance Technology have made it relatively easy to install your own surveillance system. The first step is to understand the different technologies available for recording video.

The effectiveness of your Video Surveillance system is based around one thing, the quality of the recorded images. There are currently three types of head end recording solutions currently being offered in the video surveillance market. They are the Analog/Time Lapse Recorder (VCR) Systems, the Digital Hard Drive Recording Systems which operate like a VCR but utilize hard-drives to store video and the top of the line PC Based Digital Video Recording Systems or DVR’s.

The use of Time Lapse Video Tape Recorders in the video surveillance industry started a little over 25 years ago. The first systems required a Video Recorder and a monitor for every camera. Innovations in the industry included the video multiplexer and splitters that allowed multiple cameras to be viewed and recorded on a single video tape. Until 4 or 5 years ago, this technology was still the most prevalent form of recording video.

A Time Lapse Recorder has a single video input that allows you to record the incoming video signal. A standard VCR records and plays back video at about 30 frames per second, which on a standard T-160 video tape allows you to record 2-hours of video. A time lapse video recorder slows down the rate at which the images are recorded. Some Recorders allow you to extend the recording up to 960 hours onto a single video tape.

Be aware that when you are recording 960 hours on one VCR tape you are only recording 1 frame or picture every 9 seconds. When programming a time lapse recorder I strongly recommend you do not set the recording duration for more than 3 days or 72 hours. This setting allows you to record over a weekend without changing the tape. Three days of recording on one tape records 1.5 frames or pictures per second. Not great, but not bad considering this is a 20 year old technology.

This works O.K. for a single camera system. Let’s say for example you need 4, 8 or even 16 cameras to watch your property. You could either purchase a monitor and a time lapse recorder for each camera, or you can add a video multiplexer.

A video multiplexer allows you to view and record multiple cameras on a single time lapse recorder and video monitor. Multiplexers are offered in color or black & white in 4, 9 or 16 camera configurations. A video multiplexer works by digitally separating the incoming video signals and dividing them out, one at a time, to a time lapse recorder. It sends the image from camera 1 to frame 1, camera 2 to frame 2, camera 3 to frame 3 and so on. An added benefit of multiplexers is the ability to view multiple cameras simultaneously on a single CCTV Monitor.

A major drawback is that during the digitizing of the incoming video signals, about ½ of the information contained in the image is lost. Also remember that you are now limiting the total number of images per second for any given number of cameras. With 16 cameras recording on a single video tape for 72 hours, you are now getting about 1 frame of video from each camera about every 3 seconds.

If a video is recorded on a time lapse recorder through a multiplexer, you must use a time lapse recorder and a multiplexer for playback. A standard VCR cannot process the digital multiplexing encoded in the time lapse format and will not provide a useful playback.

With the advent of the digital age, manufacturers soon devised a way to combine the best features of the Time Lapse Recorder and the Video Multiplexer into a single system that utilizes hard drives rather than VCR tapes to store the recorded images.

Hardware based digital video recorders operate much like a VCR, complete with shuttle and jog controls. Most will utilize some type of traditional CCTV or SVGA Video monitor to view the video.

These units are built from the ground up to perform one specific function, record video. While they do operate some software internally, the video processing is hardware based. It is this hardware which provides the live viewing and high resolution recording. Many of these systems can record high resolution video from 16 or more cameras at up to 160 images per second.

No more VCR tapes are required as all of the video is recorded onto hard drives. How long the video can be stored is merely a function of the total images per second being recorded, the size of the image files and the total size of the installed hard drive(s).

In addition, these recorders utilize a process called first-in first-out to process video (FIFO). They will record video until the designated amount of disk space has been used. Then the system will delete the oldest clips and record the new video. This provides a continuous loop of recordings at anytime.

Some other interesting benefits of digitally processing the video are features such as motion or event based recording options and advanced playback capabilities. In the old days of VCR’s & Multiplexers, it could literally take many hours to try and find an event that occurred overnight. Now, the advanced digital search functions allow you to find archived video in seconds, not hours.

A PC based DVR is comprised of a computer, video capture cards and a software package that allows full motion video to be recorded and played back on a standard personal computer. Due to their superior processing speeds, some of these 16 camera systems are capable of recording up to 480 images per second, which equates to 30 images per second, or real time video for every camera connected to the system.

Many people consider the PC based Digital Video Recorders to be much easier to use and more flexible than the Digital Hard Drive Recorders, and they offer selectable recording resolution that is up to 4 times greater than the resolution of the old Time Lapse Recorders.

PC based DVR’s are programmed and operated with a keyboard and mouse. The video is recorded to the computers hard drive in a compressed format. This compression allows a huge amount of video to be stored. On average, a four camera system recording continuously will record about 30 days of video on one single 80 gig hard drive. To double the recording days simply add another 80 gig hard drive.

PC based DVR’s are designed so they do not require any scheduled actions or maintenance to provide uninterrupted video recordings. Recorded video is played back on the computer monitor and it can be printed, saved to a floppy disk or burned to a CD. These systems allow you to view and playback any combination of cameras without interrupting the systems recording process.

By yanam49

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