The performance of a mobile satellite communications link can be determined by the propagation path between a satellite and mobile users. Some of the most important factors are multipath propagation and vegetative shadowing. System designers should have the most reliable information about the statistics of fade duration in order to determine fade margin or to compensate for the fades using modulation and coding scheme. This report describes a simulator, PROSIM, developed at Virginia Tech for simulating a propagation model in land mobile satellite communications. The simulator is based on a random number generator that generates data sets to compute statistics of the propagation channel. Performance of the simulator was evaluated by comparing statistics from an analytical model and experimental data provided by W. Vogel of Univ. of Texas at Austin and J. Goldhirsh of the Applied Physics Laboratory. New expressions for phasor plot and its mathematical expression for lognormal channel were derived and were simulated. Finally, the advantages of the simulator using random number generator in simulating the propagation model are described. / Master of Science

The performance of a mobile satellite communications link is conditioned by the characteristics of the propagation path between a satellite and mobile users. The most important propagation effect in land mobile satellite system is roadside attenuation of the signals due to vegetation or urban structures. System designers should have the most reliable information about the statistics of the propagation channel to build reliable systems that can compensate for bad propagation conditions. In 1998, the Virginia Tech Antenna Group developed a simulator, PROSIM, to simulate a propagation channel in the case of roadside tree attenuation in land mobile satellite systems. This thesis describes some improvements to PROSIM, and the adaptation and validation of PROSIM for Digital Audio Radio Satellite systems operating at S-band frequencies. The performance of the simulator for S-band frequencies was evaluated through a measurement campaign conducted with the XM Radio signals at 2.33 GHz in various propagation environments. Finally, additional results on dual satellite systems and fade correlation are described. / Master of Science

In the world in which we live today, information and communication technology (ICT) has proliferated in all spheres of society, including in the corporate, social and academic arenas. Within these arenas ICT has made noteworthy contributions. In the academic space, which is the focus of this study, ICT has made a significant contribution to the communication and consultation between students and higher education institution staff. One such example has been the emergence of learning management systems (LMSs) in higher education institutions, both locally and globally, with LMSs providing higher education institutions with several possibilities as regards facilitating the online teaching and learning process. Nevertheless, research has shown that there is underutilisation of LMSs throughout the world. The purpose of this study, therefore, was to investigate the utilisation of LMSs in an open and distance learning (ODL) institution in South Africa to ascertain whether they are being used to their full potential. / Educational Studies / M. Ed. (Adult Education)

In the world in which we live today, information and communication technology (ICT) has proliferated in all spheres of society, including in the corporate, social and academic arenas. Within these arenas ICT has made noteworthy contributions. In the academic space, which is the focus of this study, ICT has made a significant contribution to the communication and consultation between students and higher education institution staff. One such example has been the emergence of learning management systems (LMSs) in higher education institutions, both locally and globally, with LMSs providing higher education institutions with several possibilities as regards facilitating the online teaching and learning process. Nevertheless, research has shown that there is underutilisation of LMSs throughout the world. The purpose of this study, therefore, was to investigate the utilisation of LMSs in an open and distance learning (ODL) institution in South Africa to ascertain whether they are being used to their full potential. / Educational Studies / M. Ed. (Adult Education)