Simplified Error Probability Curves for 'Non-Fading' and Rayleigh-Fading Digital Links, and Their Application to Design Margins

Straight line relationships plus added constants for various pulse code modulations for error probability vs. carrier to noise ratio are shown to be possible for both non-fading and Rayleigh-fading radio links. These are used to show the effects of fades, relative to the nominal non-fading design, independently of the specific pulse code modulation technique. Common causes and levels of such fades are listed particularly those experienced on spacecraft aircraft to groundsea links. The relative performance of non-fading and Rayleigh-fading links with any number of diversities is discussed. Some general conclusions and guidance on fade margins are given.