Analog CCTV fundamentals

A simple analog CCTV system consists of cameras connected to a recording equipment known as DVR (Digital Video Recorder) that converts the signals from analog to digital format for recording and monitoring over the network. Once the signal is digital, it can be stored on a hard drive or sent over the network. See the diagram below:

In the first block, it is possible to see analog cameras of different types such as box, dome, PTZ, and bullet. They are connected to the DVR using coaxial cables
Traditional analog CCTV cameras have their resolution measured in TVL (TV lines) which are converted by the DVR into digital information (known as pixel).