The Research Of Receiving ACARS Signal Based On Software Radio

ACARS (Aircraft Communications Addressing and Reporting System) air-ground communication system is widely used in the civil aviation system currently. As the high bit error rate of ACARS signal and other problems have become increasingly apparent, so to study the demodulation method which can reduce the bit error rate is necessary. The frequencies of ACARS are different in the world. So the global ACARS signals received by software is of great significance.First, according to the properties of AM/MSK modulation,the corresponding demodulation algorithm for software radio platform is researched. For solving the problem of high bit error rate, the half-period sum method and slope demodulation method are used to demodulate ACARS signal. Compared with conventional MSK demodulation algorithm, the half-period sum algorithm can effectively reduce the demodulation bit error rate of ACARS signal.Secondly, this paper expounds on the coding characteristics and message structures of ACARS signal and gives a brief explanation on the common ACARS message. A method of message decoding is given. The decoding process is described in detail and the program flow chart is drawn.Finally, the method of receiving ACARS signal in the common platform of software radio is given and the receiving system is tested and validated. It meets the relevant requirements of ARINC 618 protocol.This paper makes ACARS signal received in the common platform of software radio. It effectively reduces the demodulation bit error rate. Because of the advantages of software radio, the ACARS system can be upgraded with low cost and transplanted easily. This research has a certain practical significance.