Although the application
of CCTV security have not changed very much over the past years,
the tools and equipment have significantly. Cameras became smaller,
cheaper and better, but the major breakthrough happened in recording
equipment.
Therefore many customers
shopping for complete CCTV monitoring and recording systems are
confused by such a verity of available products. Goal of this
article is to guide buyers toward best possible and most economical
type of CCTV equipment, based on intended implementation and requirements.
Selecting
the right cameras.
It is virtually impossible
to describe all types of available security cameras in this short
article. We will focus our attention on most popular and widely
used camera types instead.
CCTV security cameras
produce images using CMOS or CCD (Charge Couple Device) chips.
Tiny, very low price CCTV cameras usually use CMOS technology,
produce poor quality images and have very poor light sensitivity.
Decent quality CCTV cameras use CCD technology. The size of the
CCD chip is normally 1/4", 1/3" or 1/2". As a rule
of thumb, the larger the size, the higher the quality of the image
produced and the higher the price. However, higher density 1/4"
and 1/3" CCD chips can now produce as good an image as many
1/3" or 1/2" chips.
The number of TV lines
in the security camera image is a measure of picture resolution
(sharpness). The larger the number of TV lines, the better the
resolution and hence, overall picture quality. Standard resolution
camera may have 350-380 lines, over 400 TV Lines is generally
considered good resolution while over 500 TV lines is considered
high resolution. B/W chip cameras produce greater resolution and
better light sensitivity, therefore suitable for use in dark areas
where light conditions are poor most of the time.
On the other hand color
cameras offer more realistic and natural picture. CCTV cameras
are usually divided into different types based on the body of
the camera used.
Professional
grade cameras.
Have box type body
with the ability to use different types and size of lenses. Exchangeable
lenses enable this camera, to monitor objects from virtually any
distance.
Although for indoor
use, they can be used for outdoor when combined with weatherproof
housing. They are considered to be the most flexible and widely
used by professionals for commercial installations.
Bullet
cameras.
Bullet cameras are,
as the name suggest contained inside bullet shaped housing.
Most bullet cameras
are weatherproof and sealed without the ability to use different
lenses. Great advantage of bullet camera is the small size and
integrated design, some bullet cameras will even have infrared
LED future built-in. Infrared technology is simply LED light in
infrared spectrum (not visible to human eye). This light will
illuminate viewing area, making possible monitoring in complete
darkness. This is great future, but it only works up to certain
distance (usually between 10 and 50 ft. depending on model) Vary
simple to install and esthetically designed, bullet cameras are
great choice for residential and do-it-yourself installations
where monitoring objects are within about 25ft from the camera
location (with standard 3.6mm lens).
Board
Cameras.
Board Cameras are basically
fixed lens mounted on a circuit board. These cameras may be packaged
in a small case (Mini Cameras) or dome (Mini Dome) or simply sold
unpackaged, for mounting by the purchaser. Lenses in these cameras
are either of a normal industry aperture or a "pinhole"
lens of very small aperture. Pinhole lens cameras are often called
"spy" cameras and may be mounted in a concealed way
for covert surveillance purposes. The most popular examples of
covert board cameras are smoke detector and motion detector cameras.
Since the lenses in
board cameras are pre-mounted, have a fixed iris and are usually
of a short focal length (i.e. wide angle), their flexibility of
usefulness is limited. However, this type of camera can provide
a low cost solution in the right situation, particularly in a
home environment.
We have shortly described
most popular types of cameras, lets now discus, how and where
they mite be used.
Professional type cameras
with C/CS mount lens attachment generally offer best performance
and many important futures, like lens control output, Back Light
Compensation and many more…
Distance from monitoring
object to the camera is not an issue, that is why ability to select
different lenses, based on camera location is so important. Installation
is bit complicated and professional installation strongly recommended.
We recommend this type of security cameras for commercial installations.
Most Bullet cameras
in comparison, do not offer high resolution and lens selection
flexibility, but are likely to be weatherproof, some will have
infrared light built-in and most of all they are relatively easy
to implement.
Bullet cameras usually
come with 3.6mm lens witch are considered to be suitable for most
standard installations (good for covering small to medium size
room or equivalent).
For larger rooms or
longer distances, cameras with 6mm or higher lens may be required.
They are great choice
for any do-it-yourself installation.
Board cameras in contrast
are widely used in covert camera installations, sometimes called
Spy Cameras. Many wireless cameras are basically board cameras
with built-in transmitter.
We are not going to
go into wireless cameras right now, as this would be enough material
for completely new article.
Board cameras are sold
as plain circuit board, for integrating into hidden camera devices.
They are also available in dome housing, as vary popular Dome
Camera or integrated with Smoke Detector, Motion Detector, Exit
Sign and so on.
Most board cameras
also come with 3.6mm lens although some will allow lens to be
replaced.
Over the time, most
practical design has been Dome Camera with its esthetic appearance
it blends into surroundings, especially with drop down sealing,
great for use in stores, lobbies, gas stations and other public
places. Practical solution for covert installation are also, Motion
and Smoke Detector cameras, they are absolutely not substitute
for your security alarm or fire protection.
Cameras should always
be selected based on the location of the camera (inside/outside),
distance from the monitoring object, light condition and budget.
When shopping for security
cameras, customers are faced with the fact that they will need
to select one or another recording device.
The days of well-known
CCTV time-lapse VCR recorder are almost over.
Although some customers
still prefer this old fashioned recording solution, it is well
worth to invest some extra money to purchase a good quality digital
video recorder (DVR). Digital recorder transfers analog camera
video feed into digital format, and stores it on hard drive. There
are two major types of digital recorders on the market right now.
PC
Based Systems.
A special board and
software installed on the computer will allow camera inputs and
store video on the hard drive.
Many people are under
the misconception that personal computer with additional hardware
installed, will do the job. This explains the hundreds of companies
that have hung up a sign, taken out some ads and begun working
out of basements and garages, holding themselves out to be DVR
manufacturers and security specialists. The main problem with
this type of CCTV recorders lies in the main component of it…
Yes, it is a computer, designed to do unlimited tasks, but non
well. The truth is that any computer based digital video recorder
is, and will always be vulnerable to software crashes, hang-ups,
system instability, virus related problems etc…
Stand
Alone Systems.
Very similar in appearance
and control functions to standard VCR recorders, are truly remarkable
devices. Most video processing is done by hardware, therefore
eliminating system crashes, video is also stored on hard drive
in digital format. The basic operating system, usually Linux,
is permanently stored on special processor, witch is impossible
to overwrite or corrupt. Designed and manufactured with single
application in mind, it is by far better in performance and reliability
to its PC based rival.
Some DVR systems will
even have remote monitoring capability, useful when monitoring
is required in different locations thru Internet or network. Most
important futures to look for when selecting the right DVR recorder
are motion detection and frame speed. The higher the frame speed
the more fluent video recording. Motion detection will allow recording
video from each camera only when motion is detected; this is great
for extending video recording time.
Security
Monitors.
Video from Security
recorder could be displayed on regular TV monitor. It is OK to
do it this way, for baby monitoring or residential application,
when quality of the picture is not that important. However for
professional installation, security monitors are as much important
as cameras. They offer extended life of picture tube (necessary
with any static picture, that can cause picture burnout) and much
grater resolution.
Cables
and wiring.
Finally any camera
installation will require proper wiring. Good quality cable will
prevent video degradation over long distance runs. It is recommended
to use RG59 or RG6 coaxial cables as it is fully shielded and
will prevent video loss up to 400 ft. Coaxial cables will require
BNC connectors and proper installation possibly done by experienced
technician. In short runs plug and play non-coaxial cables with
factory installed BNC connectors may be used (up to 150 ft.).
The plug and play cables are easy enough to install by not experienced
users.
Cables for CCTV cameras
consist of two cables bundled in one jacket. One cable for video
and one for power delivery.
Conclusion.
Every CCTV system is
as good and reliable as its weakest component. With this in mind,
investing on highest quality and performance cameras, while purchasing
low performance recorder, from economical and practical standpoint
just does not make sense.
For example, why use
cameras with 500 TV lines of resolution with monitor that offers
only 380 or less. All the benefit of high-resolution camera is
effectively sacrificed by limited capability of monitor. Asking
questions is important before purchasing video security system,
and your vendor will probably be able to give more details and
recommend equipment for specific needs and requirements.
Article
Source:
http://ezinearticles.com/?expert=Robert_Moskal
