The Effect of Atmospheric Noise on the Probability of Error for an NCFSK System

A noncoherent frequency-shift-keying (NCFSK) modulation system is considered. The binary element error probability is computed when the additive noise is atmospheric (using empirical curves) and the fading obeys a gamma distribution. The fading is assumed to be flat over the frequency band occupied and slow in comparison to the baud rate. Curves displaying the probability of an element error as a function of signal-to-noise ratio are given, and a direct comparison is made with the corresponding results for idealized Gaussian noise. It is concluded that, for certain atmospheric noise conditions and fading distributions, atmospheric noise is not as harmful as Gaussian noise. However, in other cases, the probability of an error occurring in a system corrupted by atmospheric noise may be many times that of the same system affected by Gaussian noise.