Researchand Design Of Low-altitude Airspace Surveillance System Based On ADS-B

This paper discussed the low altitude airspace related technology of low altitude alarm processing and the recognition and processing of superposition signals in complex environment.It is a part of the research work of the low altitude airspace system solution that the author participated in.Automatic dependent surveillance-broadcast(ADS-B)is the aircrafts operation monitoring technology based on global positioning system(GPS).ADS-B equipments set on the aircrafts that according to the technology developed could broadcast its position information without interruption,and ADS-B equipments on the earth receive the broadcasting information and transfer the information to flight service operation center,then the center processes and applies the information.This low-altitude airspace surveillance system basede on ADS-B is the main application system in the flight service,and our paper analyzed the problems existed present days,we analyzed the differences between general aviation and civil aviation according to the general aviation characteristics,finally we designed low altitude alarming model and data management model based on the civil aviation alarm and made adaptment adjust.According to three different grade,that is reminding,warning and alarming,we designed low altitude airspace alarm,forbidden airspace alarm and conflict alarm model separately for low altitude alarming module.Low altitude alarm could automatically determine whether alarm is required according to the flight task field,and also could manually modify or set up other low altitude alarm,which is practical in practice and avoids a lot of false alarm.Forbidden airspace alarm takes the plane of the latitude perpendicular to the earth surface as a judgment surface,then determines the relationship between the forbidden space and the plane by the method of radiation,it can identify the aircraft above and under the the forbidden space.Fully considered the huge size diffrences between aircrafts,conflict alarm model has set the parameters according to aircrafts sizes in automatically set and manually modified two ways.By using the sum of the distance between vertical intervals,lateral intervals and distances and the distance between conflicts,a faster and more conflicting warning can be realized in a wider range.Considering recognizing and dealing with the complex signals at complex environment,and to improve system identification and display processing ability,we proposed an ADS-B data management module.In this module,weidentify and process data through the preamble pulse processing,position reliability judgment,error correction and error detection of the S mode response signal,then improve the system identification and display processing capability,finally get the accurate data.Low altitude alarm module realized the monitoring function of this system,and could inform the pilots when low altitude alarm,forbidden area alarm and conflict alarm to avoid danger.Data management module could provide analyzed data for alarm module and receive,filter,fuse,analyze aircraft information accurately.Through researching and designing these two modules,we realized the function and performance requirements of low altitude flight surveillance system basing on ADS-B,also we achieved the expected effect in practical application.