A Mode S decoding scheme using equalization for multilateration systems

Multilateration (MLAT) systems, which receive and decode the signals such as SSR (Secondary Surveillance Radar) Mode S reply or extended squitter in airport surface, have problems in decoding performance due to not only asynchronous interference from other aircraft, but also multipath caused by reflection from buildings and other surroundings. This paper proposes a Mode S receiver with equalization. This scheme estimates both direct wave and reflected waves by use of the received signal of preamble duration, and performs the equalization with the estimated impulse response. The evaluation results show that the scheme gives better performance than conventional decoding method for the received signal under strong multipath environment.