Patent ID: 9024803
Filing Date: 2015-05-05
Classification: G01S

Abstract:
1. A method for detecting a message provided with a preamble with a number of pulses in a radiofrequency signal sent by an interrogator or a transponder in mode S and received at an antenna, said method comprising: a step for decomposition, at a logarithmic amplifier coupled to the antenna, of said radiofrequency signal including the message with the preamble into an amplitude signal and into a complex phase signal; a step for detection, at a processing unit coupled to the logarithmic amplifier, of said preamble by correlating the amplitude signal with a replica signal of expected pulses; and a phase control step, performed at the processing unit, determining whether a trend of a phase of the radiofrequency signal is consistent with that which is expected for the preamble in the mode S by adding together samples of said phase signal for a duration of the pulses of said preamble and by analyzing the samples, to determine whether the phase signal is a sinusoidal signal, wherein the phase control step checks that the phase of the received radiofrequency signal varies according to a sinusoid by demodulating the complex phase signal into a real component I and an imaginary component Q then by comparing with a threshold the sum of a number of samples taken during the pulses on each of the components I, Q.