Real time QRS detection using adaptive threshold

Claim 3

The method of claim 1 , further comprising: filtering the raw ECG data using a non-linear filter to minimize baseline wander of each PQRST pattern to form a viewable ECG signal; and annotating the viewable ECG signal to indicate each heart beat point.

Claim 4

The method of claim 2 , wherein filtering the raw ECG data comprises: filtering the raw ECG data using a cascade of median filter and low pass filter; delaying the raw ECG data; and subtracting an output signal of the low pass filter from the delayed raw ECG data in order to deliver a high pass filtered data.

Claim 5

The method of claim 1 , wherein the amplified signal is formed by squaring the filtered ECG data at least one time.

Claim 6

The method of claim 1 , wherein filtering the third threshold signal comprises: filtering the third threshold signal with a first order infinite impulse response (IIR) filter; and dynamically selecting a cutoff frequency for the IIR as a linear function of a difference between a logarithm of the first threshold signal and a logarithm of the second threshold signal.

Claim 7

The method of claim 1 , wherein filtering the third threshold signal comprises: filtering the third threshold signal with a first order infinite impulse response (IIR) filter; and dynamically selecting a cutoff frequency for the IIR as a linear function of a ratio of the first threshold signal and the second threshold signal.

Claim 8

The method of claim 1 , wherein deriving a first threshold signal and a third threshold signal using a moving max filter on the amplified signal uses a first window width for the first threshold signal and a different window width for the third threshold signal.

Claim 9

A computer-readable non-transitory storage media having computer-readable instructions stored therein that when executed by a computer performs a method of processing ECG data in real time, the method comprising: receiving a stream of raw ECG data samples comprising PQRST patterns from an analog front end coupled to the computer; filtering the raw ECG data to form filtered ECG data by using a non-linear filter to minimize baseline wander and to suppress a T wave portion of each PQRST pattern; performing a non-linear operation on the filtered ECG data to form an amplified signal that exaggerates an R peak of each PQRST pattern; deriving a first threshold signal and a third threshold signal using a moving max filter on the amplified signal; deriving a second threshold signal using a moving average filter on the amplified signal; filtering the third threshold signal to form a filtered threshold signal using a filter in which a cutoff frequency is dynamically selected as a function of the first threshold signal and the second threshold signal; and identifying a sample in the amplified signal to be a heart beat point only when the sample value is equal to the first threshold signal and greater than the filtered threshold signal, wherein filtering the raw ECG data comprises: filtering the raw ECG data using a cascade of median filter and low pass filter; delaying the raw ECG data; and subtracting an output signal of the low pass filter from the delayed raw ECG data in order to deliver a high pass filtered data.

Claim 10

A computer-readable non-transitory storage media having computer-readable instructions stored therein that when executed by a computer performs a method of processing ECG data in real time, the method comprising: receiving a stream of raw ECG data samples comprising PQRST patterns from an analog front end coupled to the computer; filtering the raw ECG data to form filtered ECG data by using a non-linear filter to minimize baseline wander and to suppress a T wave portion of each PQRST pattern; performing a non-linear operation on the filtered ECG data to form an amplified signal that exaggerates an R peak of each PQRST pattern; deriving a first threshold signal and a third threshold signal using a moving max filter on the amplified signal; deriving a second threshold signal using a moving average filter on the amplified signal; filtering the third threshold signal to form a filtered threshold signal using a filter in which a cutoff frequency is dynamically selected as a function of the first threshold signal and the second threshold signal; and identifying a sample in the amplified signal to be a heart beat point only when the sample value is equal to the first threshold signal and greater than the filtered threshold signal, wherein filtering the raw ECG data comprises: filtering the raw ECG data using a cascade of median filter and low pass filter; delaying the raw ECG data; and subtracting an output signal of the low pass filter from the delayed raw ECG data in order to deliver a high pass filtered data.

Claim 11

The computer-readable non-transitory storage media of claim 8 , further comprising: filtering the raw ECG data using a non-linear filter to minimize baseline wander of each PQRST pattern to form a viewable ECG signal; annotating the viewable ECG signal to indicate each heart beat point; and displaying the annotated viewable ECG signal on a display coupled to computer.

Claim 12

The computer-readable non-transitory storage media of claim 8 , wherein the amplified signal is formed by squaring the filtered ECG data at least one time.

Claim 13

The computer-readable non-transitory storage media of claim 8 , wherein filtering the third threshold signal comprises: filtering the third threshold signal with a first order infinite impulse response (IIR) filter; and dynamically selecting a cutoff frequency for the IIR as a linear function of a difference between a logarithm of the first threshold signal and a logarithm of the second threshold signal.

Claim 14

The computer-readable non-transitory storage media of claim 8 , wherein filtering the third threshold signal comprises: filtering the third threshold signal with a first order infinite impulse response (IIR) filter; and dynamically selecting a cutoff frequency for the IIR as a linear function of a ratio of the first threshold signal and the second threshold signal.

Claim 15

The computer readable non-transitory storage media of claim 8 , wherein the computer readable storage media is comprised within a smart phone.

Claim 16

The computer readable non-transitory storage media of claim 8 , wherein the computer readable storage media is comprised within a medical system.