The effect of selection diversity reception on the error performance of the digital mobile radio systems is investigated. The binary frequency shift keying system (FSK) using noncoherent (NC) demodulation, with a limiter/discriminator receiver is considered. All major error causing factors, fading and Gaussian and impulsive noise, are taken into account. The corresponding general expression for the error probability (BER) is derived. This expression is used to analyse the improvements in the BER performance of the considered system gained by theM-branch selection diversity technique.