Receiver employing digital filtering for use with an implantable medical device
First Claim
1. A receiver for a modulated analog telemetry signal transmitted from a body implantable medical device, comprising:
- an antenna;
an amplifier directly coupled to the antenna to provide an unfiltered signal representative of the modulated analog telemetry signal;
a demodulator circuit coupled to the amplifier, the demodulator circuit demodulating the unfiltered signal to produce a digital information signal; and
a digital filter, coupled to the demodulator, that removes high frequency content of the digital information signal to produce a filtered digital information signal.
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Abstract
A receiving and filtering circuit includes an antenna, a demodulator circuit coupled to the antenna, and a digital median filter that removes high frequency content of a demodulated digital information signal to produce a filtered digital information signal corresponding to an analog data signal transmitted by a body implantable medical apparatus. The digital filter may include a multiple stage delay line coupled to a multiple tap selection device, a plurality of delay blocks coupled to a register, or a multiple stage delay line coupled to a voting unit. The voting unit produces a first binary output in response to a majority of delay line stages storing a first value, and produces a second binary output in response to a majority of delay line stages storing a second value. The digital filter may also comprise a digital signal processor. The digital filter may include a first filter block and a second filter block. The second filter block may be selectively activated or bypassed. The first filter block removes high frequency content of the digital information signal and the second filter block reduces high frequency noise at an edge of a data bit transition. A control circuit, coupled to the digital filter, provides for respective selection of data rate and frequency response characteristics of the digital filter. The digital filter may be implemented in a Field-Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC).
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Citations
32 Claims
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1. A receiver for a modulated analog telemetry signal transmitted from a body implantable medical device, comprising:
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an antenna;
an amplifier directly coupled to the antenna to provide an unfiltered signal representative of the modulated analog telemetry signal;
a demodulator circuit coupled to the amplifier, the demodulator circuit demodulating the unfiltered signal to produce a digital information signal; and
a digital filter, coupled to the demodulator, that removes high frequency content of the digital information signal to produce a filtered digital information signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of digitally filtering a demodulated digital data signal corresponding to a data signal produced by a body implantable medical apparatus, comprising:
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sampling a demodulated digital data signal;
storing binary values corresponding to samples of the demodulated digital data signal;
determining a binary value representing a majority of the stored binary values; and
providing a digital output signal corresponding to the majority binary value. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
establishing a fixed number of binary values to be stored;
removing a binary value corresponding to a binary value stored for a longest duration relative to other binary values; and
storing a binary values corresponding to a binary value corresponding to a most recent sample of the demodulated digital data signal.
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20. The method of claim 19, wherein the removing, storing, determining, and providing processes are respectively performed during each of a plurality of sample periods.
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21. The method of claim 15, further comprising adjusting a rate at which digital filtering is performed.
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22. The method of claim 15, further comprising adjusting a frequency response characteristic associated with digitally filtering the demodulated digital data signal.
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23. The method of claim 15, wherein the digital filtering method is performed within a Field-Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC).
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24. The method of claim 15, wherein the implantable medical device comprises one of a pacemaker, a pacemaker/cardioverter/defibrillator (PCD), an oxygen sensing device, a nerve stimulator or a muscle stimulator.
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25. An apparatus for digitally filtering a demodulated digital data signal corresponding to a data signal produced by a body implantable medical apparatus, comprising:
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means for sampling a demodulated digital data signal;
means for storing binary values corresponding to samples of the demodulated digital data signal;
means for determining a binary value representing a majority of the stored binary values; and
means for providing a digital output signal corresponding to the majority binary value. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
means for establishing a fixed number of binary values to be stored;
means for removing a binary value corresponding to a binary value stored for a longest duration relative to other binary values; and
means for storing a binary values corresponding to a binary value corresponding to a most recent sample of the demodulated digital data signal.
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29. The apparatus of claim 25 further comprising means for adjusting a rate at which digital filtering is performed.
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30. The apparatus of claim 25, further comprising means for adjusting a frequency response characteristic associated with digitally filtering the demodulated digital data signal.
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31. The apparatus of claim 25, wherein the apparatus is implemented in a Field-Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC).
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32. The apparatus of claim 25, wherein the implantable medical device comprises one of a pacemaker, a pacemaker/cardioverter/defibrillator (PCD), an oxygen sensing device, a nerve stimulator or a muscle stimulator.
Specification