4. The satellite communication is most cost effective in remote and hilly areas, such as Ladakh, Himachal Pradesh etc.
5. The satellite communication permits transmission of data at rate.
6. The satellite communication is very accurate and economical search. rescue and navigation purposes.
Demerits of Satellite Communication
1. If a system on the satellite goes out of order due to environmental stresses, it is almost impossible to repair it.
2. In satellite communication, there is a time delay between transmission and reception, due to extremely large communication path length( greater than 2 x 36000 km). This delay causes a time gap during talking, which proves quite annoying.
Remote Sensing
It is a technique of observing or measuring the characteristics of the object at a distance. A polar satellite is utilized for this purpose.
Distance upto which a signal can be obtained from an antenna is given by
d = √2hR where, h is height of antenna and R is radius of earth.
LED and Diode Laser in Communication
Light Emitting. Diode( LED) and diode laser are preferred sources for optical communication links to the following features.
1. Each produces light of suitable power required in optical communication. Diode laser provides light which is monochromatic and coherent. This light is obtained as a parallel beam. It is used in very long distance transmission.