Originally Posted by Pallavi
How the communication of UAV can be done from ground station without any delay??
There is always some delay, how ever fractional, things are rarely ever simultaneous to all observers. I doubt your planning a UAV for operation on the moon or Mars, but still something to concider (particularly if your using sat links).
So really the question is how much of a delay is acceptable. Digital video systems often have buffers, particularly on compressed video streams, as most compression systems work not just per frame, but across multiple frames, plus some sort of buffer on the receiving end to decompress and perhaps keep for smooth video playback, digital systems often have significant delays as most digital systems prioritise quality over lag.
Analog systems for example don't tend to have these issues by their inherent design, infact analog delay systems are usually quite complicated. The simplicity means you usually compromise resolution, picture quality, but you gain in immediacy.
Many small scale UAV projects that want to use a video feed to fly a UAV often use analog for video and flight controls, and digital for telemetry.