ACARS (Aircraft Communications Addressing and Reporting System)

Abstract

This work describes the design of an effective coherent signle-pass demodulator for ACARS, implemented with the GNU Radio toolkit, using two Costas loops, Viterbi al- gorithm and a polyphase filter-bank clock recovery. A way of removing the MSK signal phase ambiguity is also described here. Implemented demodulator is capable to demod- ulate in real-time, reading the data from a computer sound card, or it can work off-line, reading the data from standard input or file, both with very good number of correctly demodulated messages.