System and method for receiving telemetry data from an implantable medical device
First Claim
Patent Images
1. A programmer for a cardiac rhythm management device, the programmer comprising:
- an antenna to receive a signal transmitted from the cardiac rhythm management device, the signal being a carrier waveform modulated with transmit pulses;
an analog-to-digital converter, coupled to the antenna, to digitize the received signal;
one or more notch filters, coupled to the analog-to-digital converter, to remove narrowband noise from the received signal;
a matched filter coupled to the one or more notch filters, the matched filter adapted to produce an output signal corresponding to a cross-correlation between the received signal and a transmit pulse expected to be generated by the cardiac rhythm management device; and
a pulse detector, coupled to the matched filter, to detect the transmit pulses by comparing the output signal of the matched filter with a threshold value.
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Abstract
A system and method for receiving telemetry data from implantable medical devices such as cardiac pacemakers with improved noise immunity is disclosed. Ambient noise levels and signal strength are monitored and used to adaptively adjust the detection sensitivity of the receiver. Filtering of the received signal is performed to remove both broadband and narrowband noise. Removal of narrowband noise is accomplished with notch filters that are dynamically adjusted in accordance with a detected noise spectrum.
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Citations
27 Claims
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1. A programmer for a cardiac rhythm management device, the programmer comprising:
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an antenna to receive a signal transmitted from the cardiac rhythm management device, the signal being a carrier waveform modulated with transmit pulses;
an analog-to-digital converter, coupled to the antenna, to digitize the received signal;
one or more notch filters, coupled to the analog-to-digital converter, to remove narrowband noise from the received signal;
a matched filter coupled to the one or more notch filters, the matched filter adapted to produce an output signal corresponding to a cross-correlation between the received signal and a transmit pulse expected to be generated by the cardiac rhythm management device; and
a pulse detector, coupled to the matched filter, to detect the transmit pulses by comparing the output signal of the matched filter with a threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system for receiving data from an implantable medical device, the system comprising:
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means for receiving a signal transmitted from an implantable medical device, the signal being a carrier waveform modulated with transmit pulses;
means for producing an correlation signal corresponding to a cross-correlation between the received signal and an expected transmit pulse; and
means for detecting the transmit pulses by comparing the correlation signal with a threshold value. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method for receiving telemetry data from an implantable medical device, comprising:
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receiving a transmitted signal modulated with data from an implantable device;
digitizing the received signal into input signal samples;
filtering the input samples with a matched filter having filter coefficients corresponding to a transmit pulse;
detecting transmit pulses within the input signal samples by comparing output values of the matched filter with a pulse threshold value; and
,adjusting the pulse threshold value in accordance with measured peak values of noise and the transmitted signal. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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Specification