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Home > How do security cameras work? Understanding the basics will help you select the appropriate equipment
March 22, 2010
By: Lynn Bryant
Installing video surveillance cameras can be an excellent
way to boost security and give you peace of mind. There are
so many different options to choose from though; it can be
difficult deciding which equipment is appropriate for your
setting. It can be very beneficial to have a basic
understanding of how video surveillance equipment works
before you embark on the process of selecting equipment. In
an effort to facilitate this process, we will seek to answer
the basic question, how do security cameras work?
We will focus the answer to this question around these
four topics and terms: basic technology, analog vs. digital,
color vs. black and white, and resolution.
Basic technology
The core component behind all CCTV surveillance cameras
is a CCD, or charge coupled device, sensor. This sensor
converts the light that comes through the cameras lens into
an electrical signal. This electrical signal is then further
processed and converted into a video output. Video output
can then be recorded or displayed on a monitoring device.
How the video signal is created and transmitted varies
depending on whether the video camera is analog or digital.
We will explore the difference between the two in further
detail below.
Analog vs. digital
Digital surveillance cameras are the newest style on the
market. Prior to the onset of digital devices, all
surveillance cameras were strictly analog. In general,
digital security cameras produce a superior image quality as
compared to older analog versions. Digital surveillance
cameras generate video output using a process called Digital
Signal Processing, or DSP, by utilizing tiny computer
microchips. The analog electrical signal is passed through a
DSP chip that does analog to digital conversion, which
changes a voltage based electrical signal into binary based
digital data (ones and zeros). Analog cameras utilize
integrated circuits to process the video output, but it
remains a voltage based electrical signal. There are clear
advantages to the digital method. Images are typically of
higher quality, but more importantly there are a lot more
options for video storage and playback because the recorded
video is digital data.
Color vs. black and white
Surveillance cameras offer either black and white or
color images. In general, it is much easier to distinguish
images that appear in color, making color cameras a more
appealing choice. However, color cameras do not work well
for nighttime surveillance. A black and white camera should
be selected for operation in areas with low light
conditions. Infrared cameras that are designed for nighttime
use, often come with the ability to automatically switch
back and forth between color and black and white based on
the amount of light available.
Resolution
This is a term that is used to refer to how detailed the
picture is that a video camera can produce. Resolution is
usually measured in horizontal TV lines. A standard
resolution is typically around 350 to 400 lines. A high
resolution would be around 500. When purchasing surveillance
equipment it is important to ensure that all of the
equipment supports the highest resolution you are trying to
achieve. If your camera can achieve 500 lines of resolution,
but your monitor only displays 400, you will not gain the
image benefits gained from your high-resolution camera.
After reviewing this basic list of terms, you should have
a general understanding of some of the language used to
describe surveillance equipment. Understanding some of the
basics of surveillance technology will help you make a
better-informed purchase decision.
About the Author
Lynn Bryant is a successful freelance writer and
contributor to Video-Surveillance-Guide.com. Your
definitive guide to video surveillance equipment, CCTV
cameras and wireless security systems for home and business.
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