The Panasonic Pan/Tilt/Zoom security camera can be controlled via the RS-485 port but it also has option to control it somehow using the same co-ax as the video signal.
Can someone explain how this is done.
During vertical blanking time no video is shown ..
This interval effectively leaves open a chunk of bandwidth that can be used for data communication ..
To keep things simple, the horizontal lines are continued to be transmitted during the vertical blanking interval, but the lines do not contain video ..
Instead, each line, or group of lines contain data which is used to control camera ..