Method for managing the operation of an object that is able to contactlessly communicate with a reader

An object capable of contactless communication with a reader magnetically coupled to the object, the object comprising:

• an antenna comprising first and second terminals;
• a modulator coupled between the first and second terminals of the antenna, the modulator configured to modulate an impedance of a load connected across the first and second terminals during a transmission phase during which information is contactlessly transmitted from the object to the reader;
• a processor configured to determine an envelope of a test signal and an amplitude between peaks and troughs of the envelope;
• a comparator with a first input coupled to receive the amplitude and a second input coupled to receive a threshold;
• and
• a capacitor connected to the first and second terminals of the antenna via an auxiliary switch controlled by an output signal of the comparator, the capacitor configured to modify the impedance of the load by shifting a phase of sidebands of the test signal.

An object capable of contactless communication with a reader magnetically coupled to the object, the object comprising:

• an antenna comprising first and second terminals;
• a modulator coupled between the first and second terminals of the antenna, the modulator configured to modulate an impedance of a load connected across the first and second terminals during a transmission phase during which information is contactlessly transmitted from the object to the reader;
• a processor configured to
• determine an envelope of a modulated test signal comprising sidebands offset in frequency from a carrier frequency, and
• determine an amplitude difference between peaks of the envelope and troughs of the envelope;
• a comparator configured to
• compare the amplitude difference received at a first input of the comparator with a threshold received at a second input of the comparator, and
• send an output signal to an auxiliary switch;
• and
• a capacitor connected to the first and second terminals of the antenna via the auxiliary switch controlled by the output signal of the comparator, wherein the capacitor is configured to modify the impedance of the load by shifting a phase of the sidebands of the modulated test signal by about 90 degrees when the amplitude difference is lower than the threshold.