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What type of
security camera do I need?
A security camera can
come in many different styles including dome,
bullet,
infrared
and c-mount.
The security camera that will work best for your
application will depend on several factors such
as whether you will use the security cameras
inside or out, during the day, nighttime, or
both.
Bullet style security cameras are
the most popular. They can be used inside or
out. These security cameras come in black and
white or color and come with all of the required
mounting hardware. The security camera casings
are weather resistant and don't require added
external protection. Most security cameras have
a fixed 4mm lens that allows you to see facial
features out to about 35 feet and provides a 70
degree angle of view. This is the widest angle
you can have without distorting the
picture.
Resolution levels for
black and white security cameras are about 400
lines, any higher and the benefits are minimal.
For color cameras, the higher the resolution the
better.
Infrared security cameras are
also very popular as they allow an image to be
seen in little or no lighting conditions. Most
infrared security cameras are bullet style and
can be used inside or out. The cameras have
infrared lighting installed around the outer
edge of the lens which allows the security
camera to see in no light for up to 25 feet -
even further with a little bit of light (like
street lighting or an outside light).
A
relatively new type of security camera to the
market is the day
/ night security camera. These types of
security cameras have an extra sensitive imaging
chip which allows it to capture a good picture
in low light situations without using infrared
leds. This is especially handy in outdoor
applications because infrared security cameras
do not do well in outdoor housings. Unless the
infrared security camera is installed flush up
to the glass of the housing, the infrared lights
can reflect off of the glass of the housing
which degrades the image.
The advantage
to c-mount security cameras is that the lens can
be changed. You'll want a special camera lens if
you need to see further than 35 ft. The color
c-mount security camera allows you to change
lenses on the camera giving you the ability to
zoom into a particular area. Varifocal camera
lenses allow you to adjust the focus from 5 to
50 mm. These lenses can be used inside only
unless you put it in special housing for outdoor
use.
Dome security cameras basically
provide a different look. Also, if you have any
concerns about tampering, check out our Infared
Armor Dome Security Camera. It will
withstand a 10 lb sledgehammer blow and can be
used inside or out, daytime or nighttime.
How does a
CCTV digital video recorder
work?
A CCTV digital
video recorder (or “DVR” for short) is
essentially a computer that saves security video
images to a hard drive. Most security cameras in
use today capture an analog picture. The DVR
converts the analog signal to digital and then
compresses it.
Many cameras can be
connected to one DVR. DVRs generally come with
4, 8, 16, or 32 camera inputs. The DVR will
allow you to view all of these images at once or
one at a time, and all of the video is saved to
the hard drive. Additional switches, quads, or
multiplexors are not required.
How big a
hard drive do I need?
The amount of hard
drive space is very important because it will
limit how many days of recording you can store
before the system has to start recording over
the oldest video. Each DVR will have its storage
capacity listed in the specifications. But this
calculation is just a rough estimate as there
are many factors that affect hard drive use. The
most critical factor being the compression
format used by the DVR. But also the type of
cameras that are connected to the DVR make a
difference (specifically the chip size and
resolution) and also the features that are
selected on the DVR. If you use the scheduling
or motion detection features or tune down the
frame rate that will extend the storage capacity
of the unit. Even the field of view (what you
are recording) will affect the storage capacity
- the more complex the image, the more hard
drive space it will take to capture the
complexity.
What features should I look for
in a CCTV Digital Video Recorder
(DVR)?
All DVRs are
definitely not made equal! There
are several factors that are critical to
consider when purchasing a DVR, especially when
comparing price. The most important factors to
look at are the number of cameras supported,
frames per second (fps), compression technology,
hard drive space, network connection / remote
viewing capability, motion detection,
scheduling, and ability to save video and audio
to a CD or flash drive. You should also look for
easy and comprehensive search capabilities
(check out our 'Smart Search' technology) and
audio support. The setup and user interface
should be intuitive and easy to operate. The
price range varies from as little as $1049 for
a basic four camera DVR up to $4399
for a 16 camera input real time
DVR.
What is frames per
second?
The frames per second (fps) relates to
how many pictures the DVR will record in a
second. Real time recording is about 30 fps on
each camera. To calculate the fps per camera
take the total fps in the system and divide it
by the number of video inputs. For example, a 60
fps digital video recorder with 4 video inputs
would result in about 15 fps per camera. The
technology has finally gotten to the point now
where real time recording is affordable. If you
are recording cash registers or something
similar then you should definitely invest in
real time recording.
What is 'Smart
Search'?
Our PC-based DVRs come standard with
smart search capability. This allows you to
highlight one area of a captured image and look
for changes just to that area. For example, if
an item is stolen off of a counter... you can go
to a moment in the video where the item is still
on the counter, then highlight the area around
the item and search automatically through the
video for the moment in time when that
particular area changes, that is precisely when
the item is removed and then view that part of
the video. Pretty slick!
Are security digital video
recorders hard to
install?
Not at all. You simply plug the cameras
into the back of the unit. For the PC-based:
Plug in the power, monitor, keyboard and mouse -
just like a regular computer. You will receive
instructions on how to set up the machine with
your shipment.
What is
the difference between a PC-based DVR and an
Embedded DVR?
A PC-based
digital video recorder is basically a personal
computer that has been modified with hardware
and software to work as a DVR. An embedded
digital video recorder is a machine that has
been manufactured specifically to work as a DVR.
In embedded DVRs there is typically one circuit
board with software burned into the chip.
There used to be
significant differences in features between the
PC-based and the embedded machines. But with
recent advancements in the embedded DVR
technologies the differences are becoming less.
The advantages of an embedded digital video
recorder is that they are extremely stable and
reliable since they contain fewer parts. The
software is often written in basic machine code
or Linux code which tends to be more stable than
Windows software. The advantages of the PC-based
digital video recorders is that they are easier
to interact with because you use the on-screen
menus and a mouse (as opposed to embedded which
you interact with more like a VCR - via
buttons). And you tend to have more features and
options on the PC-based machines.
How do I see pictures from a remote
site?
You can view the camera video over the
internet using a modem which is slow but can
display 1 or 2 frames every 5 seconds. Better is
a DSL or cable modem connection which can
generally display 1 frame per second. When
viewing remotely, the refresh rate is restricted
by the communications medium (your internet
connection speed). When viewing or playing back
locally, the display is dependent of the unit's
frame rate (fps). You will need a static ip
address available to assign to the DVR (more
about this in your documentation).
Should I purchase the card and
software and build my own digital video recorder
or buy one pre-built?
It is much better to purchase a DVR system
pre-built than to build one yourself. There are
many compatibility issues with DVR cards and
related software. They are very sensitive to the
type of motherboard in the computer, the cpu,
the memory, even the video card makes a
difference! You also don't want to be
running any other software on the computer that
your DVR is running on so you need a dedicated
computer anyway.
Analog (VCR) VS Digital
(DVR)
The most common problem for analog
systems is the degradation of the videotapes.
All too often this problem isn't recognized
until a problem occurs and the tape is unusable.
When a videotape degrades the picture becomes
grainy and blurry - this can make it impossible
to make out important details.
The effective life of a videotape depends on
the time-lapse speed of the VCR. A general rule
of thumb is to take the number 2000 and divide
that by the speed of the recorder. For example,
if the recorder is set to tape in 96-hour mode,
then the videotape will start to degrade after
only 20 uses. And the VCR itself should be
overhauled every 10,000 hours. This is precisely
why many business owners are switching to
digital video recorders (DVR) instead of
VCRs.
Since digital video recorders have very few
moving parts they require less maintenance than
a VCR. Also when there is a problem with the DVR
it is usually more evident. For example, the
system will start crashing a lot or it will stop
working altogether.
Cameras can go bad over time as well. But
again, these problems are usually fairly
evident. Periodically take the time to review
all of your cameras and make sure that the
picture on each one is crisp and
clear. |
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