Method for measuring high-accuracy realtime heart rate based on continuous-wave Doppler radar and radar system therefor

1. A method for measuring a heart rate in real time based on a continuous-wave radar, the method comprising:

receiving an in-phase (I) signal and a quadrature (Q) signal for a receive signal received through the continuous-wave radar;

selecting one signal of the received I signal or the received Q signal by comparing magnitudes of the received I signal and the received Q signal;

performing fast Fourier transform (FFT) on the selected one signal to generate a fast-Fourier-transformed signal;

performing a frequency transform using a plurality of bases on the fast-Fourier-transformed signal to generate a plurality of magnitude responses of the frequency transform, each of the plurality of bases respectively having a predetermined phase; and

determining the heart rate based on the plurality of magnitude responses of the frequency transform.

2. The method of claim 1 , further comprising:

performing zero-phase digital filtering on the received I signal and the received Q signal to generate a zero-phase-digital-filtered I signal and a zero-phase-digital-filtered Q signal, respectively,

wherein the selecting includes:

selecting the one signal by comparing magnitudes of the zero-phase-digital-filtered I signal and the zero-phase-digital-filtered Q signal.

3. The method of claim 1 , wherein the performing of the frequency transform includes:

performing discrete cosine transform (DCT) using each of the plurality of bases.

4. The method of claim 1 , wherein the determining of the heart rate includes:

determining, as the heart rate, a frequency for a largest magnitude response among the plurality of magnitude responses of the frequency transform.

5. The method of claim 1 , wherein the determining of the heart rate includes:

extracting the plurality of magnitude responses of the frequency transform;

collecting maximum values of the magnitude responses and collecting frequency information of the maximum values through peak searching in a predetermined heart rate range; and

determining, as the heart rate, a frequency with a largest value among the maximum values.

6. The method of claim 1 , wherein the performing of the frequency transform includes:

performing a discrete transform using each of the plurality of bases respectively having the predetermined phase on the fast-Fourier-transformed signal.

7. The method of claim 1 , wherein the performing of the frequency transform includes:

performing a discrete transform on the fast-Fourier-transformed signal using each of the plurality of bases respectively having the predetermined phase.

8. The method of claim 1 , wherein the performing of the frequency transform includes: enhancing resolution of a heartbeat signal in a frequency spectrum obtained by performing a discrete transform by multiplying the fast-Fourier-transformed signal by one or more of the plurality of bases, wherein one or more predetermined phases are applied to the one or more of the plurality of bases.

9. A method for measuring a heart rate in real time based on a continuous-wave radar, the method comprising:

performing fast Fourier transform (FFT) on one signal of an in-phase (I) signal of a quadrature (Q) signal for a receive signal received through the continuous-wave radar to generate a fast-Fourier-transformed signal;

performing a frequency transform using a plurality of bases on the fast-Fourier-transformed signal to generate a plurality of magnitude responses of the frequency transform, each of the plurality of bases respectively having a predetermined phase; and

determining the heart rate based on the plurality of magnitude responses of the frequency transform.

10. The method of claim 9 , wherein the performing of the frequency transform includes:

selecting the one signal by comparing magnitudes of the I signal and the Q signal; and

performing a discrete transform using each of the plurality of bases on the fast-Fourier-transformed signal.

11. The method of claim 10 , wherein the performing of the frequency transform includes:

performing zero-phase digital filtering on the I signal and the Q signal to generate a zero-phase-digital-filtered I signal and a zero-phase-digital-filtered Q signal, respectively;

selecting the one signal by comparing magnitudes of the zero-phase-digital-filtered I signal and the zero-phase-digital-filtered Q signal; and

performing a discrete transform using each of the plurality of bases on the fast-Fourier-transformed signal.

12. The method of claim 10 , wherein the determining of the heart rate includes:

extracting the plurality of magnitude responses of the frequency transform;

collecting maximum values of the magnitude responses and collecting frequency information of the maximum values through peak searching in a predetermined heart rate range; and

determining, as the heart rate, a frequency with a largest value among the maximum values.

13. The method of claim 10 , wherein the performing of the frequency transform includes:

performing a discrete transform using each of the plurality of bases respectively having the predetermined phase on the fast-Fourier-transformed signal.

14. A radar system, comprising: a baseband receiving unit configured to remove a common mode direct current (DC) component and common mode noise from each of an in-phase (I) signal and a quadrature (Q) signal; and

a signal processing unit configured to

perform fast Fourier transform (FFT) on one signal of an I signal or a Q signal output from the baseband receiving unit to generate a fast-Fourier-transformed signal, and

perform a frequency transform using a plurality of bases on the fast-Fourier-transformed signal to generate a plurality of magnitude responses of the frequency transform, each of the plurality of bases respectively having a predetermined phase; and

determine a heart rate based on the plurality of magnitude response of the frequency transform.

15. The radar system of claim 14 , wherein the baseband receiving unit removes the common mode DC component and the common mode noise by passing each of the I signal and the Q signal through an instrumentation amplifier.

16. The radar system of claim 14 , wherein the signal processing unit

selects the one signal by comparing magnitudes of the I signal and the Q signal and

performs a discrete transform using each of the plurality of bases on the fast-Fourier-transformed signal.

17. The radar system of claim 14 , wherein the signal processing unit

performs zero-phase digital filtering on the I signal and the Q signal to generate a zero-phase-digital-filtered I signal and a zero-phase-digital-filtered Q signal, respectively,

selects the one signal by comparing magnitudes of the zero-phase-digital-filtered I signal and the zero-phase-digital-filtered Q signal, and

performs a discrete transform using each of the plurality of bases on the fast-Fourier-transformed signal.

18. The radar system of claim 14 , wherein the signal processing unit

extracts the plurality of magnitude responses of the frequency transform,

collects maximum values of the magnitude responses and collects frequency information of the maximum values through peak searching in a predetermined heart rate range, and

determines, as the heart rate, a frequency with a largest value among the maximum values.

19. The radar system of claim 14 , wherein the signal processing unit performs a discrete transform using each of the plurality of bases respectively having the predetermined phase on the fast-Fourier-transformed signal.

20. The radar system of claim 14 , wherein the signal processing unit enhances resolution of a heartbeat signal in a frequency spectrum obtained by performing a discrete transform by multiplying the fast-Fourier-transformed signal by one or more of the plurality of bases, wherein one or more predetermined phases are applied to the one or more of the plurality of bases.