Nonlinear Filtering for Rejection ISI in FSK Modulation

Abstract

System DescriptionWe analyze the occurs error in binary FSK due to inter symbol interference (ISI) in mobile radioWe use here an equivalent baseband representation, so channels, with a limiter-filtering-integrator detector.the carrier frequency f, is no further importance. At the The errors are caused by bursts in the instantaneous transmitter, a binary data stream frequency modulates frequency. We propose and verify that a nonlinear the carrier, the maximum frequency deviation is ±fd frequency filtering can achieve zero error floors for and the modulation index hmod is defined as 2fdT, pure FSK by clipping offthese bursts. Forfiltered FSK,where T is the bit duration [1 ]. (Fig. 1) the error floor is not completely removed, but strongly reducedtypically by one or two orders ofmagnitude