The Detection And Decoding Technology For ADS-B Signal In UAT Mode

With the development of the aviation industry, the traditional air radar monitoringtechnology has become increasingly inadequate as for the maintenance costs and monitoringcapability. ADS-B (Automatic dependent surveillance-broadcast) technology is providingmore effective monitoring service which realizes the monitoring tasks between air aircraftand aircraft,as well as between aircraft and ground stations, thereby reducing the flightaccidents. ADS-B system has outstanding monitoring performance, higher security andreliability, while the equipment construction and maintenance costs are much lower, whichmakes the system being one of the most promising air monitoring technology in the future.With the great research value of ADS-B system, China will apply the UAT data linktechnology into the busiest general aviation area. In this paper, the main point is to analyzethe signal detection and decoding methods at the receiving end for the ADS-B signal withUAT mode. According to the development of the status quo of UAT data link in domestic orabroad, we take the points of detection for synchronization sequence of data information, anderror detection and error correction for information as the main contents for this research,other content includes ADS-B information encoding and obtaining the effective decodedinformation which is sent to the host computer to generate corresponding messageinformation.This paper first introduces the research status of the UAT data link, characteristics andworking principle of the ADS-B system, together with the components. We also compare themonitoring accuracy, update rate, equipment construction etc to traditional secondary radar.Then UAT data link features, as for the UAT data link access, information structure, supportservices are described and compared with other data link on modulation frequency, transferrate, communication capacity, monitoring range. Then, the single encoding and decodinganalyse was carried out in Matlab which provides theoretical support for the result fromhardware implementations. According to the UAT message structure, we design theimplementation of single detection and deconding scheme on the FPGA. At the same time, werealize it on the hardware with the modelsim simulation and draw the corresponding decodingcircuit board. Last we transmitted information generated to the PC through the serial port.Thehost computer deciphered the information according to the UAT ADS-B information coding standard, and generated the corresponding information of the aircraft.After practical test, in the process of decoding, the results of all modules are consistentwith theoretical analysis. In the process of signal deteciton and decoding, the operation ofsystem is stable. After reading the valid data, the system would generate message informationthat is the same as standard manual. The designs of overall system have achieved theexpected effect and meet the requirements.