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.