Method and apparatus for low complexity ultrasound based heart rate detection
First Claim
1. A method comprising:
- receiving a demodulated Doppler ultrasound signal;
applying a bandpass filter to the demodulated Doppler ultrasound signal to generate a filtered demodulated Doppler ultrasound signal;
determining a peak in the filtered demodulated Doppler ultrasound signal;
determining, using a first low-pass filter, an average of the filtered demodulated Doppler ultrasound signal;
estimating a signal-to-noise ratio (SNR) based on the peak and average of the filtered demodulated Doppler ultrasound signal;
modifying a lower cutoff frequency of the bandpass filter based on the estimated SNR when the estimated SNR is below a pre-determined SNR threshold;
applying the modified bandpass filter to the filtered demodulated Doppler ultrasound signal to generate a double-filtered demodulated Doppler ultrasound signal;
rectifying the double-filtered demodulated Doppler ultrasound signal to generate a rectified filtered demodulated Doppler ultrasound signal;
applying a second low-pass filter to the rectified filtered demodulated Doppler ultrasound signal to generate a resulting signal;
detecting peaks in the resulting signal; and
computing a heart rate based on the detected peaks.
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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.
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Citations
10 Claims
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1. A method comprising:
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receiving a demodulated Doppler ultrasound signal; applying a bandpass filter to the demodulated Doppler ultrasound signal to generate a filtered demodulated Doppler ultrasound signal; determining a peak in the filtered demodulated Doppler ultrasound signal; determining, using a first low-pass filter, an average of the filtered demodulated Doppler ultrasound signal; estimating a signal-to-noise ratio (SNR) based on the peak and average of the filtered demodulated Doppler ultrasound signal; modifying a lower cutoff frequency of the bandpass filter based on the estimated SNR when the estimated SNR is below a pre-determined SNR threshold; applying the modified bandpass filter to the filtered demodulated Doppler ultrasound signal to generate a double-filtered demodulated Doppler ultrasound signal; rectifying the double-filtered demodulated Doppler ultrasound signal to generate a rectified filtered demodulated Doppler ultrasound signal; applying a second low-pass filter to the rectified filtered demodulated Doppler ultrasound signal to generate a resulting signal; detecting peaks in the resulting signal; and computing a heart rate based on the detected peaks. - View Dependent Claims (2, 3, 4, 5)
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6. A heart rate monitoring system comprising:
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a bandpass filter adapted to; receive a demodulated Doppler ultrasound signal; filter the demodulated Doppler ultrasound signal to generate a filtered demodulated Doppler ultrasound signal; a signal-to-noise-ratio (SNR) estimator coupled to the bandpass filter, the SNR estimator comprising a first low-pass filter and adapted to; determine a peak in the filtered demodulated Doppler ultrasound signal; determine, using the first low-pass filter, an average of the filtered demodulated Doppler ultrasound signal; and estimate a SNR based on the peak and average of the filtered demodulated Doppler ultrasound signal; a frequency adapter coupled to the SNR estimator and adapted to modify a lower cutoff frequency of the bandpass filter based on the estimated SNR when the estimated SNR is below a pre-determined SNR threshold; the modified bandpass filter further adapted to filter the filtered demodulated Doppler ultrasound signal to generate a double-filtered demodulated Doppler ultrasound signal; a rectifier coupled to the frequency adapter and adapted to rectify the double-filtered demodulated Doppler ultrasound signal to generate a rectified filtered demodulated Doppler ultrasound signal; a second low-pass filter coupled to the rectifier and adapted to filter the rectified filtered demodulated Doppler ultrasound signal to generate a resulting signal; a microcontroller coupled to the second low-pass filter and adapted to; detect peaks in the resulting signal; and compute a heart rate based on the detected peaks. - View Dependent Claims (7, 8, 9, 10)
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Specification