Digital algorithms for suppression of adjacent channel interference in FM receivers

Two novel digital algorithms are 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 digital phase-locked loop (CC-BB-DPLL), which avoids the problem of changing the synchronization. Much better compensation results are possible by using the second algorithm, called the forward compensation structure (FCS). The FCS is a simplified CC-BB-DPLL with internal intermediate-frequency (IF) filtering. The complete signal estimation including an adaptive compensation algorithm is presented. All the filter and estimation structures are optimized using FM model processes generated by the Monte Carlo method.<>