METHOD FOR DETECTING A MESSAGE TRANSMITTED BY AN INTERROGATOR OR A TRANSPONDER IN MODE S

摘要

The present invention relates to a method for detecting a message provided with a preamble having a plurality of pulses in a signal transmitted by an interrogator or a transponder in mode S, said method performing a step of breaking said signal down into an amplitude signal (205) and a complex-phase signal (207), a step (240) of detecting said preamble by correlating the amplitude signal (205) with a reply signal of the expected pulses, said method being characterised in that a phase-control step (250) is carried out by adding together samples of the phase signal during the flow time of the pulses of said preamble and comparing the resulting sum with a threshold value. The method may include a step of time-synchronisation by correlating the complex-phase signal (207) with a reference sequence consisting of one or more bits known prior to decoding the data. The invention can be used in particular for decoding inquiry messages carried by low-power signals.