The Design Of ADS-B Signal Decoding Board And Message Processing

ADS-B (Automatic dependent surveillance-broadcast) technology as the next generationof air traffic management monitoring technology has been widely used in the world. It canmonitor the space aircraft and provide ground station and can also complete the relevantmonitoring directly between plane and plane. Pilots and ground station control personnel canall benefit from it, thereby reducing the risk of accidents. With the development of ADS-Btechnology, we can make better use of it to complete the air traffic control task, for thedevelopment of civil aviation has played a huge role in promoting.The traditional ADS-B technology is mainly based on the three data transmission mode,namely: Mode S1090ES, UAT and VDL MODE4.We study based on the1090MHz datalink, this paper discusses the ADS-B information decoding algorithm, and the data errordetection and correction process, and the conversion of data message generation is realized inPC end, finally proposed the hardware implementation scheme, and realize the whole processof signal processing in hardware.In the decoding process of signal, before the ADS-B signal is sent into the decoder boardthe sampling frequency is controlled by preceding the A/D and signal encoding for the PPM(pulse position modulation), because the S mode of traditional ADS-B decoding has high biterror rate. The decoding method changed the original threshold method; make full use of thesignal obtained by sampling from the discrete amplitude information, complete the decodingprocess signal, the signal error is obtained by simulation rate is lower than the originalalgorithm.This paper first describes the development process of ADS-B system and the situation athome and abroad, the basic composition of ADS-B system, working principle, and thenintroduced the ADS-B basic signal data structure, encoding method, discusses4kinds of datalink format, and the parameters in the1090ES mode ADS-B signal setting, composition andcharacteristics, and then introduces the principle the ADS-B signal decoding algorithm, thebasic principle of CRC error detection and correction algorithm, and the basic principle ofCRC correction algorithm is verified, including the analysis of simulation on signal decodingprocess. Then this paper introduces the basic design process of message processing systemsoftware, including the software platform selection, methods of extracting data information, and generating message specification. Finally, the hardware design scheme on the overallsignal decoding board, including the choice of DSP chip, peripheral options, interface and PCterminal. And the completion of the test the overall test of the system and each algorithm,gives the test results, verify the decoding function.