Slant path fade and rain-rate statistics associated with the COMSTAR beacon at 28.56 GHz for Wallops Island, Virginia over a three-year period

Abstract

Rain-fade and rain-rate statistics covering a three-year period for Wallops Island, VA are presented. The attenuation statistics were derived from continuous measurements of beacon signals at 28.56 GHz emanating from the COMSTAR ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D_{2}</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D_{3}</tex> ) geostationary satellites. The rain-rate statistics were determined from continuous measurements of precipitation with tipping-bucket rain gauges. Descriptions are given of the yearly, overall average, monthly, and time-of-day fade as well as the yearly and overall rain-rate distributions. Relatively small year-to-year variations are noted for both the fade and rain-rate statistics; however, relatively large year-to-year changes are noted for the monthly and time-of-day cases. For example, the extreme average probability variations for the year-to-year cases are within <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\pm20</tex> percent relative to the average distribution over the fade interval from 3 to 25 dB. Over the rain-rate interval, 4-50 mm/h, the extreme probability deviations are within <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\pm25</tex> percent relative to the three-year average rain-rate distribution. Probability deviations of factors of two or more are noted, however, for the yearly variations in both the monthly and time-of-day statistics. Using effective parameter concepts coupled with the 28.56-GHz attenuation and rain-rate measurement, the cumulative fade distribution at 19.04 GHz is predicted. This, as well as the measured 28.56-GHz fade distributions are compared with those predicted using the International Radio Consultative Committee (CCIR) global model, and excellent agreement is noted.