SYNCHRONIZATION BETWEEN A READER AND AN OBJECT COMMUNICATING WITHOUT CONTACT WITH THE READER BY ACTIVE CHARGE MODULATION

摘要

Data frames are transmitted from the object to the reader, each frame comprising load active modulation carrier signal bursts, called MAC, generated from a modulation of a subcarrier by a modulation scheme . The synchronization between a reader carrier signal (SH2) and the MAC carrier signal (SH1) comprises: before each transmission frame and between at least some of the MAC carrier signal bursts of each transmission frame, a slaving of the output signal (SSP) of a controlled main oscillator (OSCP) on the phase and frequency of the reader carrier signal (SH2) and an estimate of a frequency ratio between the frequency of the output signal (SSP) and a reference frequency, and during each MAC carrier burst of each transmission frame, a frequency slaving only of the output signal (SSP) on the frequency of the reference signal corrected by said estimated ratio, said MAC carrier signal (SH1 ) coming from the output signal (SSP).