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:
- executing an algorithm having a plurality of ratio determinations of foreground seizure energies divided by background seizure energies, in which the algorithm uses a ratio estimation in place of fixed point division to determine a majority of the ratios,wherein the ratio estimation includes estimating a Numerator (N) divided by a Denominator (D), the estimating including obtaining a result as a function of 2 raised to the power of the difference between the most significant set bit position (MSSB) of the D and the MSSB of the N; and
generating an indication of a detected seizure at least in part as a function of the ratio determinations with the self-powered IMD or the self-powered wearable medical device.
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Accused Products
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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executing an algorithm having a plurality of ratio determinations of foreground seizure energies divided by background seizure energies, in which the algorithm uses a ratio estimation in place of fixed point division to determine a majority of the ratios, wherein the ratio estimation includes estimating a Numerator (N) divided by a Denominator (D), the estimating including obtaining a result as a function of 2 raised to the power of the difference between the most significant set bit position (MSSB) of the D and the MSSB of the N; and generating an indication of a detected seizure at least in part as a function of the ratio determinations with the self-powered IMD or the self-powered wearable medical device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification