In this entry, we would like to share some important information and tips when selecting the solution for CCTV security camera system. This is the basic guideline before you made decision on purchasing the system.
We always heard people said "Analog camera is cheaper than IP camera", That statement would only be right if people comparing low resolution camera with higher resolution camera. In fact, if you do visit CCTV online retailers, they always putting a cheap price which bundled with cameras+DVR. People tend to quickly grab the deals by just looking the word "H.264" or "Full 960H" or "HD".
Before we go further explanation, first thing you should know is about TVL.
TVL (Television Line) is the specification of an analog camera or the screen's horizontal resolution power. This is the main factor in determining the CCTV resolution.
Resolution is the "overall picture sharpness" and measured by counting horizontal line and vertical line of an image. (the white line is also counted as a line in an image).
To make it quick understanding:
a) Horizontal Line
- it depends on the camera specification (which stated in analog camera model spec)
- also depends on display capability
- and bandwidth used
b) Vertical Line
- independent to system bandwidth
- depend primarily on the number of scanning lines per pictures.
But in most cases, when you buy a cheap camera, they don't put the TVL as part of the camera's specification (as customers may know that it is a low quality camera). Instead, the advertise the camera as, for example "960H/WD1" or "QCIF", "CIF" etc.
Table shown below may help you to further understand the relationship between these term and pixel :
And table below shown the relationship between TVL and pixels count:
For the next tips on selecting CCTV security camera system, please do visit our next entry.
Thanks.
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