Aeronautical Telecommunication Network
The Aeronautical Telecommunication Network (ATN) has been designed to provide data communications services to Air Traffic Service (ATS) provider organizations for ATS communication, aeronautical operational control, administrative communication, and aeronautical passenger communication (Doc. 9880-AN/466, 2005; Doc. 9896, 2011). The ATN comprises application entities and communication services, which allow ground-ground, air-to-ground and air-to-air data subnetworks to interoperate using satellite subnetwork (Roddy, 2006).
Satellite communication systems are used for sending data from aircraft to a ground stations accessible to Aeronautical Operation Control (AOC), Air Traffic Management (ATM) and Air Traffic Control (ATC). Wide application of satellites in aviation is connected with the possibility of communication with a considerable amount of aircraft irrespective of a distance, with independence of expenses on a distance between planes, with insignificant influence of atmosphere and sites of land stations on reliability of communication.
A satellite tracking of aircraft is a technology available to aircraft operators that has huge benefits and relatively low costs. An aircraft can report its position via an Aircraft-Satellite-Ground Station data link. Automatic Dependent Surveillance – Broadcasting (ADS-B) – is a technology, which allows pilots and air traffic controllers to track aircrafts with high accuracy (EUROCONTROL, 2013; ADS-B, 2014). ADS-B can make flight safe and allows using of air space more effective. An aircraft equipped with ADS-B avionics transmit their exact position in space by means of digital communication channels. The digital code which contains this information is updated several times per second and transmitted by aircraft on discrete frequencies. ADS-B systems based on Low Earth Orbit (LEO) satellites are of special interest (Osborne, & Xie, 2009).
It was found (Aircraft-to-Satellite Links, 2003) that the most critical factors for all systems using aircraft are the transmitting antenna and the data rate that the communications system is required to carry. The maximum rate for any system in use today is set by the transmit power available from the ground (or aircraft) transmitter and the sensitivity of the satellite receiver. Therefore, it is necessary to determine the amount of data that must be transmitted and the time period in which the transmission must occur. Problems connected with the performance of satellite aeronautical communication channel are very important. Even small degradation of communication channel parameters influences a rate of data transmission, a time delay and a coverage. These factors at once impact on safety of flights and operational expenses. It is necessary to have the system parameters optimized before implementation (Elbert, & Elanix, 2009) and when things go wrong, a simulation model can be used to track down the offending element. The imitation modeling also may be useful for pre-testing any corrective action before attempting it either in space or on the ground. At the same time the role of a satellite transponder as a part of the microwave repeater and antenna system is significant. A transponder is used to amplify carriers on the downlink side. Each transponder is amplified by either a traveling wave tube amplifier or a solid state power amplifier.