MODELLING OF NON LINEARITY AND INTERMODULATION NOISE EVALUATION IN F.D.M.-A. SATELLITE COMMUNICATION SYSTEMS

Abstract

The unique feature of interconnecting a large number of ground stations through a single, satellite has given a very important place to multiple access systOms in the modern world of satellite communications. Two modes of multiple accesses presently used are fre.. quency division multiple access and time division mul-tiple access. Frequency division multiple access satellite communication systems -frequently employ a single T.W,T.A. for transmission. The nonlinear amplitude and phase characteristic of T.W.T.A. imposes many problems on transmission such as intermodul.ation, signal suppression etc. The basic purpose of the dissertation is to study the various models which have been proposed so far for charac-terizing the nonlinearity effects of T.W°.T.A.. The coefficients of the polynomial model and Fourier Bessel Series model are, nett, calculated using least square method of curve fitting, The intermodulation noise computation is, then made by Fourier Bessel Series model using the coefficients obtained.