Seasonal Distribution Modeling and Mapping of the Effective Earth Radius Factor for Microwave Link Design in South Africa

Abstract

Abstract-In this paper we present seasonal results of the effective earth radius factor distribution in South Africa using recently (2007)(2008)(2009) acquired radiosonde data from the South African Weather Service (SAWS) for seven locations in South Africa. Two data modeling methods are used to formulate the solution for the distribution of the effective earth radius factor.The seasonal effective earth radius factor statistics obtained from the radiosonde measurements are then interpolated, gridded and presented in contour maps to cover the rest of the country for the four seasons defined by ITU-R recommendation P.453-10. The Integral of Square Error is used to check the performance of the data modeling techniques while the Root Mean Square Error is used to compare the performance of the different interpolation methods used.

Interpolation and mapping of the median k-factor for terrestrial link applications in South Africa

“…In this paper, the two methods used are validated using the Root Mean Square error (RMSE) and the Mean Absolute Error (MAE). These errors are given by [6,14,17]:…”

“…This is achieved by making use of semivariogram modeling from which matrices are derived to enable the computation of the weights used in the prediction. The weights are then computed using the following relation [14,16]:…”

“…Hence, the nearer the data point to the prediction point, the greater its contribution to the prediction and vice versa. The IDW weights are computed by using the formula [14,16]:…”

“…Using this model, they were able to produce contour maps of the k-factor exceeded 0.001 of the time at an arbitrary height cut-off of 200m above sea level. Nyete and Afullo [14,15], have also developed three-year annual and seasonal curve fitting and kernel models of the k-factor for seven locations in South Africa.…”

Estimation of Clear-Air Atmospheric Effective Earth Radius (K-Factor) in Calabar

“…In the bid to improve on the coverage, capacity and quality of service for radio wave communication systems, experts have found that the propagation of radio signals through the atmosphere is greatly influenced by the effective earth radius factor k [5,6,7,8]. Particularly, the k-factor is largely dependent on one of the most important parameters of radio wave propagation known as refractivity gradient as considered in the lowest 65m from the ground level [9,10,11]. Variations in refractivity may cause radio waves to bend while propagating through dissimilar layers of the atmosphere [12].…”