Division approximation for implantable medical devices
First Claim
1. A method for detecting a seizure in an implantable or wearable medical device (IMD), the method comprising:
- generating a plurality of ratio determinations of foreground seizure energies divided by background seizure energies;
generating a majority of the plurality of ratio determinations using a ratio estimation comprising estimating a Numerator (N) divided by a Denominator (D) to generate a ratio result, the estimating including raising 2 raised to the power of a difference between a most significant set bit position (MSSB) of the D and a MSSB of the N; and
generating an indication of a seizure with the IMD or the wearable medical device based at least in part on the plurality of ratio determinations.
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Abstract
Methods and devices for performing division approximation in implantable and wearable self-powered medical devices. The present invention provides rapid methods for performing an approximation of division on fixed point numbers, where the methods are easily implemented in small, low power consumption devices as may be found in implantable medical devices. One example of use is in rapidly determining the approximate ratio between foreground and background activity in seizure detection algorithms. Some methods approximate the ratio of Numerator (N) to Denominator (D) by raising 2 to the power of the difference in the number of zeros to the left of the Most Significant Set Bit (MSSB) of D vs. N. Some methods may also pad bits to the right of the approximate ratio MSSB using bits from the right of the N MSSB, and/or pre-process the smaller of D or N by rounding the value upward. Methods may be implemented in firmware and/or in discrete logic.
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Citations
11 Claims
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1. A method for detecting a seizure in an implantable or wearable medical device (IMD), the method comprising:
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generating a plurality of ratio determinations of foreground seizure energies divided by background seizure energies; generating a majority of the plurality of ratio determinations using a ratio estimation comprising estimating a Numerator (N) divided by a Denominator (D) to generate a ratio result, the estimating including raising 2 raised to the power of a difference between a most significant set bit position (MSSB) of the D and a MSSB of the N; and generating an indication of a seizure with the IMD or the wearable medical device based at least in part on the plurality of ratio determinations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification