Multiple implant communications with adjustable load modulation based on received signal amplitudes

A method of communicating between a telemetry controller and a plurality of medical devices implanted within a patient, the telemetry controller having a primary coil and each of the medical devices has a secondary coil, wherein coupling coefficients between the primary coil and the secondary coils differ from each other, the method comprising:

• applying a primary carrier signal having an envelope to the primary coil, thereby respectively inducing a secondary carrier signal having an envelope on each of the secondary coils;
• generating data by each of the implanted medical devices;
• measuring an amplitude of the secondary carrier signal on each of the secondary coils;
• sequentially amplitude modulating each of the secondary carrier signal envelopes in accordance with the data generated by the respective implanted medical devices, thereby inducing amplitude modulations of the primary carrier signal envelope on the primary coil for the implanted medical devices, wherein the secondary carrier signal envelopes are modulated based on the measured amplitudes of the respective secondary carrier signals, such that a variation of a peak-to-peak amplitude of the induced amplitude modulations of the primary carrier signal envelope between the implanted medical devices is decreased;
• and
• amplitude demodulating the induced amplitude modulations of the primary carrier signal envelope to acquire the data from the implanted medical devices.