Medical device telemetry receiver having improved noise discrimination

A telemetry system for receiving information-encoded, telemetry signals transmitted from one of an implantable medical device (IMD) or an external programmer to the other of the external programmer or IMD employing a telemetry antenna and transmitter circuit in a telemetry transmission, wherein each of said IMD of said external programmer comprises:

• a telemetry antenna tuned circuit comprising at least one antenna coil and at least one tuning capacitor, the telemetry tuned circuit adapted to be driven into oscillation to generate tuned circuit output signals in response to telemetry transmissions of telemetry signals and in response to electrical noise, whereby the tuned circuit output signals can exhibit noise artifacts due to contamination by such electrical noise;
• a telemetry receiver section for detecting and demodulating the telemetry signals from the tuned circuit output signals and providing a demodulated signal having a demodulated signal amplitude that varies with time as a function of telemetry signal amplitudes and noise artifacts;
• an adaptive comparator circuit for comparing the demodulated signal amplitude with the threshold amplitude of an adaptive threshold signal and providing a receiver output signal when the demodulated signal amplitude exceeds the adaptive threshold amplitude of the adaptive threshold signal, the comparator circuit further comprising
• means for filtering and integrating the demodulated signal to derive an adaptive threshold amplitude that is proportional to and adapts to the amplitude of noise artifacts in the demodulated signal;
• and
• comparison means having a first input terminal for receiving the demodulated signal and a second input terminal for receiving the adaptive threshold signal and an output terminal for comparing the demodulated signal amplitude with the adaptive threshold amplitude and providing the receiver output signal at the output terminal only when the demodulated signal amplitude exceeds the adaptive threshold amplitude.

A method of receiving information-encoded, telemetry signals transmitted from one of an implantable medical device (IMD) or an external programmer to the other of the external programmer or IMD employing a telemetry antenna and transmitter circuit in a telemetry transmission, wherein each of said IMD or said external programmer comprises:

• a telemetry antenna tuned circuit comprising at least one antenna coil and at least one tuning capacitor, the telemetry tuned circuit adapted to be driven into oscillation to generate tuned circuit output signals in response to telemetry transmissions of telemetry signals and in response to electrical noise, whereby the tuned circuit output signals can exhibit noise artifacts due to contamination by such electrical noise;
• and
• a telemetry receiver section for detecting and demodulating the telemetry signals from the tuned circuit output signals and providing a demodulated signal having a demodulated signal amplitude that varies with time as a function of telemetry signal amplitudes and noise artifacts;
• the method comprising the steps of:
• filtering and integrating the demodulated signal to derive an adaptive threshold signal having an adaptive threshold amplitude that is proportional to and adapts to the amplitude of noise artifacts in the demodulated signal;
• and
• comparing the demodulated signal amplitude with the adaptive threshold amplitude and providing a receiver output signal when the demodulated signal amplitude exceeds the adaptive threshold amplitude of the adaptive threshold signal.

In a telemetry receiver for receiving information-encoded, telemetry signals transmitted from one of an implantable medical device (IMD) or an external programmer to the other of the external programmer or IMD employing a telemetry antenna and transmitter circuit in a telemetry transmission, wherein the receiver further comprises:

• a telemetry antenna tuned circuit comprising at least one antenna coil and at least one tuning capacitor, the telemetry antenna tuned circuit adapted to be driven into oscillation to generate tuned circuit output signals in response to telemetry transmissions of telemetry signals and in response to electrical noise, whereby the tuned circuit output signals can exhibit noise artifacts due to contamination by such electrical noise;
• a telemetry receiver section coupled to the telemetry antenna to detect and to demodulate the telemetry signals from the tuned circuit output signals and to provide a demodulated signal having demodulated signal amplitude that varies with time as a function of telemetry signal amplitudes;
• and
• an adaptive comparator circuit coupled to the telemetry receiver section to receive the demodulated signal, to generate an adaptive threshold signal indicative of a level of the electric noise in the demodulated signal, and to provide a filtered receiver output signal when the adaptive threshold signal has a predetermined relationship to the demodulated signal.