Research Of Extending The Range Of Land-Air VHF Communication

Recent years, because of the air flow rate increased and the separation of air traffics reducing year by year, the air traffic environment have become increasingly crowded and dangerous, How to expand and improve the air traffic control in the VHF signal coverage to become the important topic. This paper mainly revolves around VHF signal coverage algorithm analysis and research, by considering of the effects of atmospheric refraction, the influence of the earth’s surface, the coverage of field strength loss, keep out of the ground, and so on. Put each stations’ information to establish mathematical model which is about the VHF signal coverage. To improve and optimize the existing VHF coverage calculation method based on the algorithm by VB programming language. Developed the new "VHF signal coverage auxiliary system" software which is very useful in the practical work.Based on the software, expand control zones project in Shenyang area as the background, analysis and calculation the remote control device’s engineering standard and the r station signal coverage of current situation. Put forward the problems existing in the present situation and the insufficiency and build a more accurate overlay. By using the overlay analysis, found the shenyang area expanded control planning of the planning scheme of VHF signal coverage, the problems of three aspects:(1) Between Xiwu and Wulan, There are 40 km range communication blind zone on A588 air line.(2) There are two different stations cover together which use the same frequency signal overlap have 120 km of same frequency interference on A326 air line.(3) In practice, a smaller range of overlapping signals will communication echo phenomenon, seriously will affect flight safety.According to these three aspects of remote control station system equipment of practical problems, put forward improvement ideas:(1) Effect in improving Land-Air VHF Communication distance aspect, I put forward to high gain antenna or antenna orientation, which made its propagation distance increasing, and verified the conclusion by calculation.(2) In eliminating Land-Air VHF Communication with frequency interference phenomenon, I set up frequency offset on radio to prevent frequency interference phenomenon.(3) VHF communication signal echo eliminate of unhealthy phenomenon aspects, I put forward to comparison optimization technology, passing the experiment and collecting the statistics.Through the above research and analysis, it realized optimization that the remote control station of communication coverage.