Detection of direct sequence spread spectrum signals in the presence of harmonic and narrowband interferences

This paper presents simulation results of an adaptive transform domain filter that is implemented for harmonic (CW) and narrowband (NB) interference rejection before the standard detection methods for direct sequence (DS) spread spectrum signals are applied. Both chip rate (CRD) and carrier frequency (CFD) detection methods of DS signals are considered. Complex versions of desired and interference signals are implemented. Signal sources, transform domain filter and detector models are developed using the Matlab Simulink software. Simulation results of the transform domain filter application and its adaptive threshold adjustment algorithm seem to prove that this method is very efficient and computationally effective in cases of harmonic and other narrowband interferences.