Study On The Extraction Methd And Verify Based On The Civil Aviation Aircraft Real-time Parameter Information

According to the core algorithm "Locating the ground interference sources using the Doppler Shift Effect" proposed by State Radio Monitoring Center, we can locate the position of the interference source and thereby prevent the ground interference sources to intentionally or unintentionally interfere with the aircraft when we are aware of the state of flight and the conditions of ground receiving station location. ADS-B(automatic dependent surveillance broadcast) receiving device available on the market can demodulate all kinds of ADS-B message format, but they are relatively expensive. This paper uses software defined radio technology for demodulating ADS-B signal to obtain identity information, the location, altitude, and speed of the aircraft to meet the localization algorithm’s needs. The software defined radio has the advantage of low cost, strong portability and easier to maintain.Firstly, this paper introduces automatic dependent surveillance broadcast technology through the aspects of the research background, significance and status quo at home and abroad. Secondly, this paper presents the principle and the basic structure of the system and describes the characteristics and principles of ADS-B transmit subsystem and receive subsystem in detail. Thirdly, introducing the ADS-B message format, highlight coded meaning of the various sub-fields in DF = 17 packets and it also describes implication of the height and the speed of encoding field in detail. Fourthly, Analyses pulse format of ADS-B message, thenz explain the detection and decoding design the ADS-B signal based on the software defined radio technology. Detect and decode the signal through the acquisition of RF front-end I/Q data, and then detect and correct 1-bit and 2-bit error for packets information through conduct the CRC check with check list.Finally, we verify the reliability and real time of the demodulating information by the Doppler Effect with using the large amounts of data collected in the test. Fit the aircraft Doppler shift curve according to the aircraft information and the interference sources coordinates and the interference signal frequency. And then plot the Doppler shift curve based on the aircraft’s Doppler frequency shift information accepted by the spectrum analyzer. Comparing the similarity degree of these two curves to decide real-time and reliability of aircraft signal demodulation based on the software defined radio technology.