Security cameras are no exception and in fact, the many different specifications and functions available quite often confuses the average buyer. As this is a guide made for the not-so-technically-inclined, we won’t bore you with the details about how the image sensors absorb light and transfer them into electronic signals or how TV lines are related to bandwidth.
2. ◦ Security cameras are no exception and in fact, the many different
specifications and functions available quite often confuses the
average buyer. As this is a guide made for the not-so-technically-
inclined, we won’t bore you with the details about how the image
sensors absorb light and transfer them into electronic signals or how TV
lines are related to bandwidth. Instead, we bring you the meat, the
details, and important facts you can use.
3. 1. Image Sensors
CMOS
◦ Uses only 1/5 to 1/10 as much power as CCDs
◦ Cheap due to low cost of production
◦ Great for battery-powered wifi cameras
CCD
◦ Less electronic noise than a CMOS
◦ Better image quality
Super HAD CCD
◦ Twice as sensitive as traditional type of CCD
◦ Has a 6 db better smear rejection ratio than the
formal traditional type of CCD
◦Interline CCD
◦High resolution
◦Large pixels for high sensitivity
◦High frame rates with multiple outputs
◦Fast line dump for faster sub-sampling
◦Low image lag and smear
◦Great for machine vision, microscopy, fluoroscopy,
and other applications that demand high imaging
performance.
4. ◦ In the end, which is best? You might quickly vote for the Interline CCD, and you might
be right, but recent advances in technology have minimized any quality differences
between CMOS and CCD, so to a beginner I would say: It’s pretty much the same
since image quality does not solely depend on the image sensor. Look at the other
specifications too.
5. 2. TV Lines
◦ “TV Lines” refer to the horizontal resolution measured in relation with the picture’s height.
That is, for a standard 4:3 aspect ratio, your 720 pixels accross the screen divided by 4/3
would give a max of 540 TV lines in theory. Of course, it depends on the lens, the ccd, the
camera output direct to a monitor, etc. The important thing to know is: The more the better.
◦ Causes for low TVL :
1.A poor quality or badly set-up camera.
2.A poor quality or poorly focussed lens.
3.Poor quality video cables. These can cause distortion of the high frequency analog signals.
4.The network bit rate used to transmit the video. If the bit rate is too low then TVL will be
reduced.
5.Product quality. Poor design of the analog to digital conversion electronics can greatly
reduce TVL.
6.
7. 3. Wired/Wireless
◦ There are many reasons to choose wired security cameras and many reasons to choose
wireless security cameras. When making that decision, there are plenty of factors to
consider: the size of your home or property, the placement of the cameras, the cost, even
weather and network interference. Wireless security cameras with long signals are very
convenient because you can place them in many different, hard-to-reach spots, without
worrying about wires or cords. The signals can also go up to 1000 feet, which means you can
have your wireless security cameras in areas that didn’t have the proper outlets for regular
wired security cameras. Wired security cameras, on the other hand, tend to be more cost
effective. You never have to worry about dropping the signal or worry about obstructing or
otherwise affecting the wired security cameras signal. One is obviously not inferior to the
other, there is only one better for your needs.
