A method and a device for phase-differentiated digital demodulation and a microwave communication system applied in particular to the automatic toll on paid taxiways.

摘要

The invention relates to a microwave communication system exchanging information, according to a determined protocol, between a fixed beacon and at least one badge detected by the beacon implementing a method and a digital phase differentiation demodulation device consisting of demodulating a signal (E) having undergone a two-phase differential modulation type S also called FMO modulation, and received by a homodyne receiver (21 to 37) allowing the formation of a first channel (I) and a second channel (Q ) respectively carrying a signal (11) in phase and a signal (Q1) in phase quadrature with the input signal (E) of the receiver (21 to 37), and comprising, to overcome the need for a converter analog-digital input at the input of each channel (I and Q), means (47 and 49 to 52) for comparing the absolute values of the amplitudes of the two output signals of the channels (I and Q), the result of this comparison giving condi (CI Q, C1, C2, C'1 and C'2), and calculation means using the operating results of these conditions (CI Q, C1, C2, C'1 and C'2) by a determined operating logic, for calculating the difference in state of the output signal taken between the current sampling time (t) and the previous sampling time (tT), the time interval separating these two sampling times corresponding to a bit time (T). BR/ Application: Motorway tolls and others. / P