Heart rate measurement using adaptive harmonics filtering

1. A method for heart rate measurement, comprising:

determining, with a computing device, a respiratory rate (RR) and respiration displacement from radar-measured cardiorespiratory motion data;

adjusting, with the computing device, notch depths of a harmonics comb notch digital filter (HCNDF) based upon the respiration displacement, wherein the respiration displacement is determined from a respiration fundamental frequency and respiration demodulation-generated (DG) harmonics identified from the radar-measured cardiorespiratory motion data;

generating, with the computing device, filtered cardiorespiratory data by filtering the radar-measured cardiorespiratory motion data with the HCNDF; and

identifying a heart rate (HR) from the filtered cardiorespiratory data.

2. The method of claim 1 , wherein the notch depths are based upon amplitudes of the respiration fundamental frequency and the respiration DG harmonics.

3. The method of claim 1 , wherein the notch depths are based upon one or more ratios of the respiration fundamental frequency and the respiration DG harmonics.

4. The method of claim 1 , comprising adjusting notch frequencies of the HCNDF based upon the RR.

5. The method of claim 4 , wherein the notch frequencies of the HCNDF correspond to a fundamental frequency of the RR and harmonics of the fundamental frequency.

6. The method of claim 5 , wherein the HCNDF comprises notches corresponding to the fundamental frequency of the RR, a second harmonic frequency, and a third harmonic frequency.

7. The method of claim 6 , wherein the HCNDF further comprises notches corresponding to a fourth harmonic frequency and a fifth harmonic frequency.

8. A method for heart rate measurement, comprising:

determining, with a computing device, a respiratory rate (RR) and respiration displacement from radar-measured cardiorespiratory motion data;

adjusting, with the computing device, notch depths of a harmonics comb notch digital filter (HCNDF) based upon the respiration displacement, wherein notch widths of the HCNDF are based upon a length of a time window over which the radar-measured cardiorespiratory motion data was obtained;

generating, with the computing device, filtered cardiorespiratory data by filtering the radar-measured cardiorespiratory motion data with the HCNDF; and

identifying a heart rate (HR) from the filtered cardiorespiratory data.

9. The method of claim 8 , comprising adjusting the notch widths of the HCNDF in response to a change in the length of the time window.

10. The method of claim 9 , wherein the notch widths are reduced in response to an increase in the length of the time window.

11. The method of claim 8 , comprising adjusting notch frequencies of the HCNDF based upon the RR.

12. The method of claim 11 , wherein the notch frequencies of the HCNDF correspond to a fundamental frequency of the RR and harmonics of the fundamental frequency.

13. A system, comprising:

radar circuitry configured to transmit a single-tone carrier signal and receive a cardiorespiratory motion signal reflected from a monitored subject; and

signal processing circuitry configured to:

determine a respiration displacement from cardiorespiratory motion data based upon the cardiorespiratory motion signal;

adjust notch depths of a harmonics comb notch digital filter (HCNDF) based upon the respiration displacement;

generate filtered cardiorespiratory data by filtering the cardiorespiratory motion data with the HCNDF; and

identify a heart rate (HR) from the filtered cardiorespiratory data,

wherein the signal processing circuitry comprises data acquisition circuitry configured to sample quadrature signals of the cardiorespiratory motion signal and a processor configured to determine the respiration displacement and identify the HR based upon the sampled quadrature signals.

14. The system of claim 13 , wherein the radar circuitry comprises a Doppler radar transceiver coupled to transmit and receive antennas.

15. The system of claim 13 , wherein the respiration displacement is determined from a respiration fundamental frequency and respiration demodulation-generated (DG) harmonics identified from the cardiorespiratory motion data.

16. The system of claim 15 , wherein the notch depths are based upon amplitudes of the respiration fundamental frequency and the respiration DG harmonics.

17. The system of claim 15 , wherein the notch depths are based upon one or more ratios of the respiration fundamental frequency and the respiration DG harmonics.

18. A system, comprising:

radar circuitry configured to transmit a single-tone carrier signal and receive a cardiorespiratory motion signal reflected from a monitored subject; and

signal processing circuitry configured to:

determine a respiration displacement from cardiorespiratory motion data based upon the cardiorespiratory motion signal;

adjust notch depths of a harmonics comb notch digital filter (HCNDF) based upon the respiration displacement, wherein notch widths of the HCNDF are based upon a length of a time window over which the cardiorespiratory motion data was determined;

generate filtered cardiorespiratory data by filtering the cardiorespiratory motion data with the HCNDF; and

identify a heart rate (HR) from the filtered cardiorespiratory data.

19. The system of claim 18 , wherein the signal processing circuitry is further configured to adjust notch frequencies of the HCNDF based upon a respiratory rate (RR) determined from the cardiorespiratory motion data.

20. The system of claim 19 , wherein the notch frequencies of the HCNDF correspond to a fundamental frequency of the RR and harmonics of the fundamental frequency.

21. The system of claim 18 , wherein the signal processing circuitry is further configured to adjust the notch widths of the HCNDF in response to a change in the length of the time window.