R-R interval measurement using multi-rate ECG processing
A method and system for R-R interval measurement of a user are disclosed. In a first aspect, the method comprises detecting an electrocardiogram (ECG) signal of the user. The method includes performing QRS peak detection on the ECG signal to obtain a low resolution peak and searching near the low resolution peak for a high resolution peak. The method includes calculating the R-R interval measurement based upon the high resolution peak. In a second aspect, a wireless sensor device comprises a processor and a memory device coupled to the processor, wherein the memory device includes an application that, when executed by the processor, causes the processor to carry out the steps of the method.
1. A method for R-R interval measurement of a user using a wireless sensor device, the method comprising:
detecting an electrocardiogram (ECG) signal of the user;
performing QRS peak detection on the ECG signal to obtain a low resolution peak;
searching proximate the low resolution peak for a high resolution peak by scanning a range of ECG sample points that span to the left and to the right of the low resolution peak; and
calculating the R-R interval measurement based upon the high resolution peak.
2. The method of claim 1 , wherein the detecting is at a high sampling rate, further comprising:
filtering the ECG signal using an anti-aliasing filter;
converting the ECG signal from an analog domain to a digital domain using an analog-to-digital converter (ADC);
filtering the digital ECG signal using a band-pass filter;
down-sampling the digital ECG signal at a low sampling rate;
processing at least one ECG sample of the digital ECG signal using a digital signal processing (DSP) algorithm to detect a peak of the down-sampled ECG signal; and
searching near the peak of the down-sampled ECG signal at the high sampling rate for the high resolution peak.
3. The method of claim 2 , wherein the processing further comprises:
processing every fourth ECG sample of the digital ECG signal using a robust digital signal processing (DSP) algorithm to detect a peak of the down-sampled ECG signal.
4. The method of claim 2 , wherein the range of ECG sample points spans from 3 points to the left to 3 points to the right of the low resolution peak.
5. The method of claim 1 , wherein the detecting is at a low sampling rate, further comprising:
filtering the ECG signal using an anti-aliasing filter;
converting the ECG signal from an analog domain to a digital domain using an analog-to-digital converter (ADC);
filtering the digital ECG signal using a band-pass filter;
processing the digital ECG signal using a digital signal processing (DSP) algorithm to detect the low resolution peak; and
searching near the low resolution peak for the high resolution peak.
6. The method of claim 5 , wherein the searching further comprises:
interpolating between the range to obtain high resolution interpolated samples; and
searching within the high resolution interpolated samples to determine the high resolution peak.
7. The method of claim 6 , wherein the range of ECG sample points spans from 10 points to the left to 10 points to the right of the low resolution peak and wherein the searching within spans from 3 points to the left to 3 points to the right of the high resolution interpolated samples.
8. The method of claim 1 , wherein the calculating further comprises:
comparing the high resolution peak with another previously calculated high resolution peak to compute the R-R interval calculation.
9. The method of claim 1 , further comprising:
attaching a wireless sensor device to the user via at least one electrode; and
detecting the ECG signal of the user by the wireless sensor device.
10. The method of claim 1 , wherein the low resolution peak is a QRS peak at a lower sampling rate of 125 Hz.
11. The method of claim 1 , wherein the high resolution peak is a QRS peak at a higher sampling rate of 500 Hz.