Abstract

Satellite based communication either in GEO or LEO based system are prominently employed for voice, video, data communication. Demand of more traffic necessitates the data rate of satellite to be enhanced which can be implemented by the proper choice of modulation scheme. Presently ground systems are also wireless based which include direct broadcast satellite (DBS),television service, wireless local area networks (WLANs), global positioning satellite (GPS), radio-frequency identification systems which is either point-to-point or point-to-multipoint. Modern day communication systems are digital; based rather than analog to have better noise immunity. Further with the limited spectrum availability the choice of modulation scheme plays an important role for faithful transmission of the signal. The digital communication can be categorized as amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) whereas for higher bit data rate phase shift keying (PSK) such as BPSK, QPSK and OQPSK are employed. This article overview of various modulation schemes which are employed in satellite communication apart from its selection criteria along with the concept of bit error rate.