| With the vast airspace and numerous airports and the rapid development of civil aviation in our country,the number of airports and aircrafts are dramatically increased.Currently,air transport proportion of quantity in the new Modern transportation is getting bigger and bigger.Annual throughput of large airports passengers are in 10 million trips.According to the limited airspace,there is an inevitable need to significantly reduce the separation of aircraft in traffic control.The air traffic control mode has gradually been transformed from procedural regulation to current radar control,this achieves a reduction in aircraft flight intervals and the control of more aircraft in a limited time.This makes the air traffic control department more and more dependent on the protection capability of terrestrial VHF communication system which means greater security pressure.In the event of an accident,it will have a serious impact on the flight and even endanger the lives in the aircrafts.The new type of civil aviation communication with more security and service advantages based on Vo IP technology has gradually entered people’s vision,However,there are some problems that can not be ignored in the situation when it will be large-scale used.To achieve aviation VHF communication based Vo IP technology can meet the requirements for air-ground communications,under the premise of ensuring the normal operation of the system,Achieve the evaluation and improvement of system voice quality.First of all,this paper studies the key technologies and protocols in Vo IP and the key elements needed to construct a Vo IP network system.Based on this,a Vo IP-VHF based system structure is designed.Analyze system requirements and implementation methods.Subsequently,Compare and analyze the signal types,processes and features between traditional VHF communication systems and Vo IP-VHF communication systems.Put forward the idea that connects Vo IP-VHF radio to E&M transmission mode voice communication system.Then,based on the implementation of the test platform,analyze how to test the receiving/transmitting voice parameters of the Vo IP-VHF communication system,and how to quantify the voice under the premise of minimizing the influence of human factors.Finally,analyze how to use coding technology to improve packet loss in Vo IP-VHF communication systems to solve voice quality problems and reduce the impact of packet loss on the system.The results of this research shows that,matching of Vo IP-VHF radio and E&M transmission mode voice communication system is achievable.Successfully based on it,a small-scale civil aviation Vo IP-VHF communication system platform was build.Through the platform,the receiving/transmitting voice parameter indicators of the Vo IP-VHF communication system are tested and the voice quality is quantitatively evaluated.Both the parameter index and the quantitative index are in line with the civil aviation ground communication safety standard.The use of integrated coding technology can improve packet loss in Vo IP-VHF communication systems,through the preparation of the integrated coding simulation program,the simulation of the integrated coding method is implemented in Matlab,it is verified that the proposed method can effectively improve the voice quality of Vo IP-VHF communication system and reduce the impact of packet loss on the system.This paper is only put forward some preliminary ideas,do some simple work.Vo IP-VHF communication technology is a complex technology,and there are many factors that need to be considered comprehensively,the work done in this paper is still relatively idealized and simplistic in solving problems.Therefore,in the future,when Vo IP-VHF equipment is put into use on a large scale in civil aviation,there will be more problems to be considered and solved.Hope that,the results of this project can has some theoretical value and practical value in the future when Vo IP-VHF equipment used in large-scale investment in civil aviation. |
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