What is Ground wave ? When is it used for communication ?

What is "Spiegel" ? When is it used ?

Modern communication systems use

The waves used in telecommunication are

What is ground wave propagation ?

What does the term LOS communication mean? Name the types of waves that are used for this communication. Which of the two height of transmitting antenna and height of receiving antenna can effect the range over which this mode of communication remains effective?

Name the two basic modes of communication. Which one is used for telephonic communication?

In a video signal for transmission of picture. What value of bandwidth is used in communication system?

In a video signal for transmission of picture. What value of bandwidth is used in communication system?