Research Publications (Engineering and Built Environment)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215
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Item Satellite look angles, track and geometry in Mobile Satellite Communications(IEEE, 2016) Ilcev, Stojce DimovThis paper describes Satellite Look Angles, Track and Geometry in the Space and their significance with regard to the spacecraft use for Mobile Satellite Communications (MSC) systems. Basic geometric theory of satellite coordinates is applied to determine the geographical azimuth and elevation (spacecraft altitude) angles required to point mobile satellite tracking antenna to the Geostationary Earth Orbit (GEO) or Non-GEO communication satellites. The mathematical treatment introduced in this paper takes into consideration circular and elliptical orbits. During more than three decades, commercial MSC networks have utilized GEO satellites extensively to the point where orbital portions have become crowded; coordination between satellites is becoming constrained and could never solve the problem of polar coverage. However, other Non-GEO MSC solutions have recently grown in importance because of their orbit characteristics and coverage capabilities in high latitudes and Polar Regions. The important parameters of the Satellite Look Angles such as Elevation and Azimuth angles and Satellite Track and Geometry such as Longitude and Latitude values are described.Item Spacecraft launching technique and systems(IEEE, 2016) Ilcev, Stojce DimovIn this paper is presented the spacecraft launching technique and different rocket systems. The launch of the satellite and controlling support services are a very critical point in the creation of space-based communication technology and the most expensive phase of the total system cost. At the same time, the need to make a satellite body capable of surviving the stresses of the launch stages is a major element in their design phase. Satellites are also designed to be compatible with more then one model of launch vehicle and launching type. In a more determined sense, the multi-stage expendable and manned or unmanned reusable launchers are described. Owing to location and type of site here are discussed land-based and sea-based launch systems. The new sea launch multinational system was developed more than ten years ago to overcome the cost of land-based launch infrastructure duplication around the world. Additional rocket motors during launching procedure, such as perigee and apogee kick propulsion systems, may also be required.Item Airborne antenna systems for DVB-RCS solutions(IEEE, 2016) Ilcev, Stojce DimovThis paper introduces development and implementation of new Airborne Satellite Antenna (ASA) used for Very Small Aperture Terminal (VSAT) of Aeronautical Satellite Broadband System (ASBS) known as a Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS). Directional High Gain Antenna (HGA) of ASA system usually needs to be protected by special radome and always positioned in the focus of satellite by a special antenna mechanical and electrical antenna tracking mechanism situated on the special stabilized pedestal. The several possible types of broadband ASA via different Radio Frequency (RF) band, such as Ku-band transceiving, airborne satellite broadband antenna, L and Ku-band antennas for DVB-RCS and Internet Protocol Television (IPTV) solutions, Ka-band transceiving antenna system for DVB-RCS solutions, Antenna Systems for Aeronautical Satellite Broadcasting (ASB) are discussed.Item Implementation of orbit constellations for Satellite Distress and Safety Systems (SDSS) of Cospas-Sarsat network(IEEE, 2016) Ilcev, Stojce DimovIn this paper is described implementation of different orbit constellation, such as Polar Earth Orbits (PEO), Medium Earth Orbit (MEO) and Geostationary Earth Orbit (GEO) in function of the Satellite Distress and Safety Systems (SDSS) of Cospas-Sarsat networks for all mobile applications. The panel of International Maritime Organization (IMO) together with Inmarsat mobile satellite operator provided technical and economical studies regarding the extension of the GEO satellite system and to cover Polar Regions. This initiative was performed by international Cospas-Sarsat in designing LEO-polar constellation for full Earth coverage. Some important features of a constellation are introduced such as type of polar and other satellites orbits needed for continues coverage in function of combined distress and safety communication solutions for all Mobile Earth Stations (MES) at sea, on the ground and in the air.