acta satech Journal of the Life & Physical Sciences Babcock

Digital Algorithms for Suppression of Adjacent Channel Interference in FM-Receivers
1Ibitola G. A. & *2Ehinlafa O. E.
1Department of Pure and Applied Physics, Caleb University, Imota, Lagos. 2Department of Physics, University of Ilorin, Ilorin, Nigeria.
Accepted: July 1, 2011

In this paper, two new digital algorithms were presented, which allow the demodulation of an FM signal in broadcasting, even if there is one adjacent channel interference with overlapping spectra, which is stronger than the desired signal. The first algorithm is the Cross-Coupled-Baseband DPLL (CC-BB-DPLL), which avoids the problem of changing the synchronization. This is a main problem in proposed CC-PLL systems. Much better compensation results are possible by using the second algorithm called Forward Compensation Structure (FCS), which is presented in this paper for the first time. The FCS is a simplified CC-BB-DPLL with internal Intermediate Frequency (IF)-filtering. The complete signal estimation including an adaptive compensation algorithm was presented. All the filter and estimation structures are optimized using FM model processes generated by the Monte-Carlo Method.
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