Digital Modulation Techniques

Abstract

Living in the era of communication every thing may be video, audio or any information in the form of electrical signal is termed as data and there is an enormous requirement of data transfer between two or more point through the world wide web, every moment of the clock, which is a big threaten to the existing communication systems because of the problems like spectral congestion, severe adjacent and co-channel interference problems and noise corrupted data reception etc. This has resulted in serious need for the research work all around the world for the development of the communication systems which can handle the above said problems, where each aspect of the communication systems is dealt with the development of new encoding techniques, modulation techniques, possibilities for newer transmission channels and of course the demodulation and decoding techniques. The design of a communication system is application oriented and is dependent on the type of the signal. The choice of digital communication technique over its analog counter part becomes more evident of the fact that it provide larger immunity to noise for even at the price of large bandwidth requirements, where as the requirement of video, audio and data over the computer network or the mobile telephony network termed as the third generation (3G) mobile communication poses a serious problem for the bandwidth. So the existing modulation techniques need to be modified for the purpose where it can handle both the situations of noise and bandwidth efficiency. The major advantage of using digital modulation technique is that the use of digital signals reduces hardware noise and interference problems as compared to the analogue signal where large number of waveforms will be required resulting in a larger bandwidth for the symbol to be transmitted.