Fade Duration and Interfade Interval Statistics Measured on a 19-GHz Earth-Space Path

Signal attenuation due to rain is the primary source of outages on earth-satellite radio links operating above 10 GHz. Measurements of the durations of rain fades are also useful in assessing link performance since the effect of many short outages is clearly different than that of fewer long outages. In this paper the authors present a set of measurements of the number and duration of rain fades measured at 19.04 GHz along an earth-satellite path with 18.5 degree elevation. Since rain attenuation is seasonally dependent, one would expect some seasonal variation in at least the rate of occurrence, and possibly the durations of rain fades. This paper briefly examines this dependence. Another factor affecting the performance of earth-satellite RF links is the distribution of time intervals between rain fades, called here `interfade intervals'. If the probability of short interfade intervals were high, this could adversely influence the link performance for services with long holding times. This paper presents measured distributions of these intervals.