Development of a Prototype Direct Digital Synthesized QAM Modulator using Code Composer Studio Forapplication in Mobile Communication Systems

With the increase in the spectral congestion and dramatic enhancement in the numbers of mobile telephone users, many approaches are being considered to reduce the bandwidth requirement of each user. One approach is the use of quadrature amplitude modulation (QAM) for mobile radio applications. QAM multilevel modulation can offer an attractive solution to current bandwidth restriction in microcellular networks. The conventional method of QAM synthesis is analog and quite cumbersome. In this paper an attempt has been taken for the experimental synthesis of 8-QAM using the principle of direct digital synthesis (DDS) with the help of digital signal processor (DSP) TMS320VC5416. The synthesized QAM signal has been generated by writing a program in the C-source file of Code Composer Studio (CCStudio) Integrated Development Environment (IDE). Experimental results for two sets of tri-bit modulating sequence are included