The Open Automation and Control Systems Journal

2015, 7 : 386-397
Published online 2015 May 29. DOI: 10.2174/1874444301507010386
Publisher ID: TOAUTOCJ-7-386

One Joint Demodulation and Despreading Algorithm for MOD5

Li Huan , Zhao Feng , Li Yu Bai and Wang Jian
University of Electronic Science and Technology of China, Sichuan, 611731, P.R. China.

ABSTRACT

IFF determines the response properties of the target to identify friend or foe through question and answer mechanism, and nowadays it plays an important role in the modern information warfare. This paper introduces the transponder digital processing system in the new type of IFF, specially including the processing method of receiving and transmitting in MOD5 and the theory of basic MSK modulation, maximum likelihood Viterbi demodulation and Walsh spreading and despreading, discussing the shortage of maximum likelihood Viterbi demodulation, then proposing the weighted MSK demodulation and despreading algorithm and joint demodulation and despreading algorithm based on the improved maximum likelihood Viterbi demodulation algorithm. The joint demodulation algorithm is more outstanding than the maximum likelihood Viterbi demodulation algorithm according to simulation.

Keywords:

MOD5, Walsh, Maximum likelihood Viterbi demodulation algorithm, Joint demodulation and despread.