Method and Apparatus for Low Complexity Ultrasound Based Heart Rate Detection

• US 20150094592A1
• Filed: 09/25/2014
• Published: 04/02/2015
• Est. Priority Date: 09/27/2013
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Ravindran, Sourabh, Spaulding, Jonathon David
• Granted Patent: US 10,376,243 B2
• Time in Patent Office: Days
• US Class Current: 600/453
• CPC Class Codes: A61B 8/02 Measuring pulse or heart rate
• CPC Class Codes: A61B 8/462 characterised by constructional features of the display
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: A61B 8/5207 involving processing of raw data to produce diagnostic data, e.g. for generating an image reconstruction G06T11/00
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A method for ultrasound based heart rate detection in a heart rate monitoring system is provided that includes receiving a demodulated Doppler ultrasound signal, applying a bandpass filter to the demodulated Doppler ultrasound signal to remove a direct current (DC) component and out-of-band noise, wherein a filtered demodulated Doppler ultrasound signal is generated, rectifying the filtered demodulated Doppler ultrasound signal to generate a rectified filtered demodulated Doppler ultrasound signal, applying a low-pass filter to the rectified filtered demodulated Doppler ultrasound signal to filter out undesired components to leave a resulting signal corresponding to power shift due to heart rate, detecting peaks in the resulting signal, and computing a heart rate based on the detected peaks.

Claims

1. A method for ultrasound based heart rate detection in a heart rate monitoring system, the method comprising:

receiving a demodulated Doppler ultrasound signal;

applying a bandpass filter to the demodulated Doppler ultrasound signal to remove a direct current (DC) component and out-of-band noise, wherein a filtered demodulated Doppler ultrasound signal is generated;

rectifying the filtered demodulated Doppler ultrasound signal to generate a rectified filtered demodulated Doppler ultrasound signal;

applying a low-pass filter to the rectified filtered demodulated Doppler ultrasound signal to filter out undesired components to leave a resulting signal corresponding to power shift due to heart rate;

detecting peaks in the resulting signal; and

computing a heart rate based on the detected peaks.

2. The method of claim 1, wherein rectifying the filtered demodulated Doppler ultrasound signal comprises applying one selected from a group consisting of an active full wave rectifier or an active half wave rectifier to the filtered demodulated Doppler ultrasound signal.

3. The method of claim 1, wherein the demodulated Doppler ultrasound signal is an in phase (I) component of the Doppler ultrasound signal.

4. The method of claim 1, further comprising:

calibrating the bandpass filter to a person using the heart rate monitoring system.

5. The method of claim 4, wherein calibrating the bandpass filter comprises:

iteratively adapting a lower cutoff frequency of the bandpass filter until a sufficient signal-to-noise ratio (SNR) is achieved.

6. The method of claim 5, wherein iteratively adapting comprises estimating an SNR of a peak in the filtered demodulated Doppler ultrasound signal and an average signal as generated by applying a low-pass filter to the filtered demodulated Doppler ultrasound signal.

7. The method of claim 1, wherein a passband of the low-pass filter is set to a highest expected frequency for a heart rate.

8. The method of claim 7, wherein the highest expected frequency is 4 Hertz.

9. A heart rate monitoring system comprising:

circuitry for applying a bandpass filter to a demodulated Doppler ultrasound signal to remove a direct current (DC) component and out-of-band noise, wherein a filtered demodulated Doppler ultrasound signal is generated;

circuitry for rectifying the filtered demodulated Doppler ultrasound signal to generate a rectified filtered demodulated Doppler ultrasound signal;

circuitry for applying a low-pass filter to the rectified filtered demodulated Doppler ultrasound signal to filter out undesired components to leave a resulting signal corresponding to power shift due to heart rate;

means for detecting peaks in the resulting signal; and

means for computing a heart rate based on the detected peaks.

10. The heart rate monitoring system of claim 9, wherein the circuitry for rectifying the filtered demodulated Doppler ultrasound signal implements one selected from a group consisting of an active full wave rectifier or an active half wave rectifier.

11. The heart rate monitoring system of claim 9, wherein the demodulated Doppler ultrasound signal is an in phase (I) component of the Doppler ultrasound signal.

12. The heart rate monitoring system of claim 9, further comprising:

circuitry for calibrating the bandpass filter to a person using the heart rate monitoring system.

13. The heart rate monitoring system of claim 12, wherein the circuitry for calibrating the bandpass filter is configured to iteratively adapt a lower cutoff frequency of the bandpass filter until a sufficient signal-to-noise ratio (SNR) is achieved.

14. The heart rate monitoring system of claim 13, wherein the iterative adaptation comprises estimating an SNR of a peak in the filtered demodulated Doppler ultrasound signal and an average signal as generated by applying a low pass filter to the filtered demodulated Doppler ultrasound signal.

15. The heart rate monitoring system of claim 9, wherein a passband of the low-pass filter is set to a highest expected frequency for a heart rate.

16. The heart rate monitoring system of claim 15, wherein the highest expected frequency is 4 Hertz.