Filtering telemetry signals emitted by a medical device
First Claim
1. A filter (26), for receiving at an input a first signal delivered by a receiving circuit (16-24) in response to a second signal emitted by a medical device (10), the second signal being in the form of a magnetic induction, said medical device comprising a metallic case having a material and a geometry, the filter characterized in that it comprises a compensation stage (42) having in the frequency domain a transfer function of the form:
- ##EQU5## where fc is a parameter chosen according to the geometry and the material of the metallic case of the medical device (10), and where j=√
-1.
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Accused Products
Abstract
A device for filtering signals emitted by a medical device, principally an active implanted medical device. The device (26) receives an input that is a signal delivered by a circuit (16-24) that receives signals emitted by a medical device (10) in the form of a magnetic induction, in which the medical device has a metallic housing or case. A compensation stage (42) also is provided, having in the frequency domain a transfer function in the form: ##EQU1## where fc is a chosen parameter according to the geometry and the material of the metallic case of the medical device (10), and where j=√-1. The device is useful with medical devices that emit sequences of messages formed by symbols belonging to an alphabet of n symbols (n≧2), the compensation stage being able to reduce the rate of inter-symbol interference of collected signals that are applied to it.
107 Citations
14 Claims
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1. A filter (26), for receiving at an input a first signal delivered by a receiving circuit (16-24) in response to a second signal emitted by a medical device (10), the second signal being in the form of a magnetic induction, said medical device comprising a metallic case having a material and a geometry, the filter characterized in that it comprises a compensation stage (42) having in the frequency domain a transfer function of the form:
- ##EQU5## where fc is a parameter chosen according to the geometry and the material of the metallic case of the medical device (10), and where j=√
-1. - View Dependent Claims (2, 3, 4)
- ##EQU5## where fc is a parameter chosen according to the geometry and the material of the metallic case of the medical device (10), and where j=√
- 5. In a programmer for use with a medical device having a metallic case of a geometry and a material, and emitting a signal by magnetic induction, which signal is disturbed by transmission through said metallic case, apparatus for restoring the disturbed transmission signal comprising a compensation filter having in the frequency domain a transfer function operable to invert the disturbance introduced by transmission of the signal through the metallic case.
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9. A method of filtering a signal corresponding to a magnetic induction emission from a medical device distorted by transmission through a metallic case, the signal being received by a programmer, comprising:
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providing a transfer function in the frequency domain that is the inverse of the distortion introduced by transmission of the magnetic induction emission through said metallic case; applying the transfer function to said signal, and restoring the signal to correspond to said magnetic induction emission prior to transmission through said metal case. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification