No abstract

Combining external patch antenna with Global Positioning System (GPS) portable device is necessary to control raw data quality degradation bonded with low signal strength when receiver is operating at low elevation angle. However, this work has designed an economic data collection system comprising developed adaptive graphical user interface and antenna gain enhancement module that manage the open sky GPS propagation data and characterize the signal-to-noise (SNR) as function of elevation and azimuth angles. The model which will used to characterize received SNR mobile satellite (MS) at Kano and Samarahan, show betterquality signal strength with the other one without external patch antenna, thus provide better services to MS users for this environment.

Abstract-The renowned effect of space weather is fluctuation in the amplitude of the radio signal that propagates in the ionosphere especially in the equatorial region. This fluctuation is also referred to as scintillation that will intense, degrades the signal quality, reduce the information content, or cause failure of the signal reception. Space-based radio navigation systems such as the Global Positioning System (GPS) will provide us with a unique opportunity to characterize the ionospheric scintillation effect as the signals propagate from the satellites to the GPS receiver. Sarawak, which is located near to the equatorial region, has been selected for the aim of this research. By using amplitude scintillation data recorded by the GPS Ionospheric Scintillation & TEC Monitor (GISTM), ionospheric irregularities along the path was examined and related to the signal strength performance. Methods and procedures to study and analyze the amplitude scintillation data are presented. Furthermore, the amplitude scintillation parameter is related to signal-to-noise ratio (SNR) in order to model the GPS satellite signal strength in this region. The preliminary developed SNR empirical models are a function of amplitude scintillation from the reference station path to the satellites. These contribute to the knowledge of received satellite signals strength performance in terms of ionospheric amplitude scintillation.

Abstract-Mobile satellites (MS) propagation is important for the study of satellites signal strength. This paper concentrates on the evaluation of best positioning for the experimental data acquisition system, where a portable commercial Global Positioning System receiver was used in getting the best position. The receiver azimuth angle and elevation angle were utilized in obtaining the best results. The experiment is carried out in an open space area where line-of sight will be visible. Measurement is then performed to determine the relationship between the signal performance with respect to the elevation and azimuth angles. The result obtained from this experiment will be used to set a standard and best positioning for the GPS receiver in collecting data for experimental purpose. Single frequency receivers have the advantage that they are low-cost and CA-code acquisition for civilian access provide higher signal to noise ratio than synthesized P-code acquisition. Since the civilian users can have only access of CA-code, while the P-code in mainly for military users, this kind of receiver was used in this research. Details methodology for doing the experimental works will be discussed. The experiment was conducted at roof top of faculty of engineering building, Universiti Malaysia Sarawak. Therefore, a handheld GPS receiver best positioning experiment designed in order to encourage more experimental works to be carried out in the less developed countries. The analysis of the signal performance under different MS environments is performed with respect to the information such as elevation and azimuth angles.

Abstract-Signal degradation in Mobile Satellite (MS) is due to several factors such as ionospheric effect, multipath fading, treeshadowed and building-shadowed. This affects the Mobile Satellite Service (MSS) to provide continuous communication service to the users. Since there is not adequate data available on the signal performance of the MS in the Asian continent, thus, an experimental work is essential to be carried out to investigate the effect of factors such as the tree-shadowed and buildingshadowed on the signal strength. This paper discusses the cost effective set up. It can be used to measure the effect of trees and buildings on the received mobile satellite signal operating in the L-band. The methodology uses to carry up the experimental works is discussed in detail. The measurements of the signal performance are performed under different MS environments such as tree-shadowed and building-shadowed and hence the results are compared to the data obtained for open space environment. The analysis of the signal performance under different MS environments is performed with respect to the elevation and azimuth degree at different time under a clear sky condition. The analysis produced forms an important part in the studies of the signal performance. From this research work, we would like to propose a simple and low cost data acquisition system in order to encourage more experimental works to be carried out especially in the less developed countries.