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.
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 遜 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.
A very popular feature of the PC Based Digital Video Recorders is that most
of them support remote viewing from any PC that is properly equipped by using
Windows Media Player or other remote viewing software. This can allow you to
check on your home or office from a remote location via the internet.
Which system is right for you? The final choice might come down to budget, or
custom features that you can live without, but whether you choose a tried and
true Time Lapse Recorder, or opt for a state of the art Digital Video Recorder,
you are sure to improve the safety and security of your home or office by
installing a Video Surveillance System.
