Advantages and disadvantages of Satellite Communications

Until the advent of communication satellites, the long distance communication through space could be done by using cascaded radio relays, very low frequency radio and high frequency or short wave radio. The latter two are inherently low capacity media, suitable only for specialized applications and the cascaded radio relays were limited to overland spans. Thus the satellite has filled a huge void in the sense that has been capable of transmitting high capacities over long distances, either overland or water.

Also because of its unique geometry, it is inherently a broadcast medium with a natural ability to transmit simultaneously from one point to an arbitrary number of other points within its coverage area.

The Advantages of satellite communications are,

1.  Satellite relays are inherently wide-area broadcast i.e. the point-to-multipoint, whereas all the terrestrial relays are point to point.
2. The satellite circuits can be installed rapidly. Once the satellite is in position, the earth stations can be installed and communication may be established in days or even hours. Thus a station may be removed relatively quickly from one location and reinstalled elsewhere. The terrestrial circuits of any kind would require a time consuming installation.
3. The mobile communications can be easily achieved by satellite communications as it has unique degree of flexibility in interconnecting mobile vehicles.
4. The satellite costs are independent of distance whereas the terrestrial network costs are proportional to the distance.
5. In satellite communication, the quality of transmitted signal and the locations of stations sending and receiving information are independent of distance.
6. For search, rescue and navigation efforts satellite offer the advantages which no other systems can offer.

The disadvantages of satellite communications are,

With satellite in position the communication path between the terrestrial transmitter and the receiver is approximately 75000km long. Since the velocity of EM waves is 3*10⁵ km/s,there is a delay of 1/4 second between transmission and reception of a signal. Thus between talks there is an elapse of 1/2 second.
The delay exacerbates echo which actually is caused by an imperfect impedance matching. Though  a variety of echo suppressors have been deployed  in satellite communications, one may still feel the echo.
The time delay of 1/2 second also reduces the efficiency of satellite in data transmission and long file transfers.