Suchergebnisse

Many Location Based Services (LBS), such as navigation and tracking services, are using Global Satellite-based Navigation Systems (GNSS). GNSS is the most widely used positioning solution for LBS outdoors, therefore any improvement in the quality of GNSS positioning services will directly improve the quality of LBS and therefore it will generate more revenue and attract more users. One of the upcoming satellite navigation systems is Galileo, which is being deployed by the European Union (EU). Beside all political motivations behind Galileo, the availability of more satellites in view and a more accurate, reliable and continuous positioning service are some of the technological motivations of having yet another of GNSS on sky. Such improvement in positioning service and, as a result, in LBS applications will develop the market and attract more users. However, due to long delays, current powerful competitors which are making the GNSS market increasingly crowded, and also the cost of Galileo being covered by EU taxpayers only, there is a question if another of GNSS is really required and it is able to return all its cost in near future. This chapter assesses the financial aspects of Galileo at the time of writing the book, including increasing costs and impact of losing some parts of market and also its potential revenue and the economic impact of positioning and timing service improvement by Galileo, and finally the impact of Galileo on future markets of LBS is estimated.

Intentional and unintentional radiofrequency interference (i.e., jamming) can result in degraded navigation accuracy or complete loss of the GNSS signal tracking. Jammers can be classified into three broad categories: Narrowband Jammers (NBJ), Spread Spectrum Jammers(SSJ) and Wideband Gaussian Jammers (WGJ). In recent years, a number of effective jamming detection and anti-jamming (filtering and suppression) techniques have been developed for military GNSS applications and some of them are envisaged to be used for civil purposes (e.g., terrorist attacks). The synergies between these jamming detection techniques and our newly developed Avionics-Based Integrity Augmentation (ABIA) system are investigated in this paper. In particular, GNSS vulnerability to NBJ, SSJ and WGJ types of jamming is analytically described in terms of Jamming to Signal (J/S) tracking thresholds and the models for calculating the minimum acceptable aircraft-to-jammer ranges are presented. Simulation results demonstrate that the proposed ABIA architecture is capable of performing jamming detection and avoidance when GNSS is considered as the primary source of navigation data.

Current investigations of the motions of the Arabian and its neighboring plates are primarily based on GPS measurements obtained in the surrounding areas of the Arabian plate, with few stations actually located on the Arabian plate itself in the Kingdom of Saudi Arabia. In order to advance the knowledge of the dynamics of the Arabian plate and its intra-plate deformations, the General Directorate of Military Survey (GDMS), through a collaboration with the Institute of Engineering Surveying and Space Geodesy (IESSG), densified the GPS network in Saudi Arabia, covering nearly two thirds of the tectonic plate. Since July 2002, a network of 32 GPS stations has been established at locations of the Saudi Arabia geodetic network. At all of these GPS stations a concrete pillar has been used as the monument and the locations have been selected in order to give the broadest distribution of observing sites. During 2005, 27 additional GPS stations in the Hejaz and Asser Mountains in the south-western part of Saudi Arabia, have been established, with the GDMS GPS network now comprising a total of 59 stations. In this presentation we will introduce the new GPS network in Saudi Arabia established by GDMS and will present the initial results from campaigns in March 2003 and March 2005. We show preliminary estimates of absolute and relative Arabian plate motions inferred from the GPS network and a detailed comparison of the results based on the Bernese GPS software versions 4.2 and 5.0.