Determining presence and/or physiological motion of one or more subjects with multiple receiver Doppler radar systems

• US 20080077015A1
• Filed: 05/14/2007
• Published: 03/27/2008
• Est. Priority Date: 05/17/2006
• Status: Abandoned Application

• Current Assignee: University of Hawai'i
• Original Assignee: University of Hawai'i
• Inventors: Lubecke, Victor, Boric-Lubecke, Olga, Host-Madsen, Anders
• Application Number:
  US11/803,669
• Publication Number:
  US 20080077015A1
• Time in Patent Office: Days
• US Class Current: 600/453
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/888 through wall detection
• CPC Class Codes: G01S 7/2886 using I/Q processing
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

Systems and methods for determining presence and/or physiological motion of at least one subject using a Doppler radar system are provided. In one example, the apparatus includes at least two inputs for receiving a transmitted signal (e.g., a continuous wave signal), the transmitted signal modulated during reflection from at least one subject, and logic (e.g., hardware, software, and/or firmware; including digital and/or analog logic) for determining physiological motion associated with the at least one subject (e.g., a heart rate and/or respiration rate of the subject). In one example the logic includes comparing (e.g., mixing) the received signal with the source signal. The apparatus may further comprise logic for quadrature detection of the received signals, and may include various blind source separation algorithms for detecting signals associated with separate subjects.

Claims

1. Apparatus for determining presence and/or physiological motion of at least one subject using Doppler radar sensing, the apparatus comprising:

at least two inputs for receiving a transmitted signal associated with a source signal, the transmitted signal modulated by none or at least one subject; and

logic for determining presence and/or physiological motion associated with the at least one subject based on the received transmitted signal and the source signal.

2. The apparatus of claim 1, further comprising logic for outputting analog I and Q channel data.

3. The apparatus of claim 1, further comprising logic for outputting digital I and Q channel data.

4. The apparatus of claim 1, further comprising logic for demodulating the I and Q data to remove a null.

5. The apparatus of claim 1, wherein the received modulated signal and the source signal are coupled to a mixer.

6. The apparatus of claim 1, wherein the logic comprise a 90 degree splitter for splitting the source signal into orthonormal signals, and two mixers for mixing the received signal with each of the orthonormal signals.

7. The apparatus of claim 1, wherein IQ mixing is performed in digital domain.

8. The apparatus of claim 1, further comprising at least one transmitter for causing transmission of the source signal.

9. Apparatus for determining presence and/or physiological motion of at least one subject using Doppler radar sensing, the apparatus comprising:

at least two receivers for receiving a transmitted source signal, the transmitted source signal modulated by at least one subject;

logic for comparing the received transmitted signal with the source signal; and

logic for determining physiological motion associated with the at least one subject based on the received transmitted signal and the source signal.

10. The apparatus of claim 9, further comprising at least two transmitters for transmitting source signals.

11. The apparatus of claim 10, further comprising encoding logic for encoding the source signals.

12. The apparatus of claim 11, wherein the encoding logic is operable to transmit orthogonal signals from at least two transmitters.

13. The apparatus of claim 11, further comprising an adaptive feedback system for encoding the source signals.

14. The apparatus of claim 9, wherein the logic for determining physiological motion comprises a blind source separation algorithm.

15. The apparatus of claim 9, further comprising a plurality of receiver nodes disturbed in a multistatic architecture.

16. The apparatus of claim 9, further comprising logic for compensating for signals associated with shake of a transmitter.

17. The apparatus of claim 9, further comprising logic for determining presence and cardiopulmonary motion of at least one of the subjects.

18. The apparatus of claim 9, further comprising logic for determining a location of one of the subjects.

19. The apparatus of claim 9, wherein the receivers are operable for quadrature detection of the received signal.

20. The apparatus of claim 14, wherein the blind source separation algorithm uses special characteristics of physiological motion to extract physiological sources.

21. The apparatus of claim 20, wherein the blind source separation algorithm comprises a Constant Modulus Algorithm.

22. The apparatus of claim 21, wherein the blind source separation algorithm comprises a Constant Modulus Algorithm applied after Hilbert transforming the signal.

23. The apparatus of claim 20, wherein the blind source separation algorithm operates to separate the heartbeats of at least two subjects.

24. The apparatus of claim 20, wherein the blind source separation process operates to separate the respiration rate of at least two subjects.

25. The apparatus of claim 14, wherein the blind source separation process operates to separate signals associated with shake of the receiver or transmitter.

26. Apparatus for determining physiological motion of zero or at least one subject using Doppler radar sensing, the apparatus comprising:

at least two receivers for receiving a transmitted source signal, the transmitted source signal modulated by at least one subject;

logic for comparing the received transmitted signal with the source signal; and

logic for determining a number of subjects modulating the signal.

27. The apparatus of claim 26, wherein the at least two receivers are distributed in a multistatic configuration.

28. The apparatus of claim 26, wherein the logic for determining a number of subjects comprises a blind source separation algorithm.

29. The apparatus of claim 28, wherein the blind source separation algorithm comprises a Constant Modulus Algorithm.

30. The apparatus of claim 28, wherein the blind source separation algorithm comprises a Constant Modulus Algorithm applied after Hilbert transforming the signal.

31. A method for determining presence and/or physiological motion of at least one subject using Doppler radar sensing, the method comprising the acts of:

receiving signals from two or more antennas, the signals associated with at least one transmitted source signal having been modulated by at least one subject;

comparing the received signals with the at least one source signal; and

determining cardiopulmonary motion of a subject based on the received signals and the source signal.

32. The method of claim 31, further comprising determining a number of subjects modulating the transmitted source signal based on the received signal and the source signal.

33. The method of claim 31, further comprising causing transmission of the source signal.

34. The method of claim 33, further comprising controlling the transmission of the source signal from at least two antennas.

35. The method of claim 31, further comprising using a blind source separation process to isolate at least one subject modulating the received signals.

36. A computer program product comprising computer-readable program code for sensing physiological motion of multiple subjects, the product comprising program code for:

determining physiological motion associated with at least one subject based on a source signal and a transmitted source signal having been modified by at least one subject.

37. The computer program product of claim 36, wherein the program code analyzes a mixed signal of the source signal and the transmitted source signal.

38. The computer program product of claim 36, further comprising program code for encoding a source signal for transmission.

39. The computer program product of claim 36, further comprising program code for applying a blind source separation algorithm.

40. Apparatus for determining presence and/or physiological motion of at least one subject, the apparatus comprising:

a receiver for receiving a transmitted source signal, the transmitted source signal reflected and modulated from a transponder that moves with cardiopulmonary motion of a subject, the signal further altered by the transponder; and

logic for comparing the received signal with the transmitted source signal to determine a physiological characteristic associated with the at least one subject.

41. The apparatus of claim 40, wherein the transponder comprises a wearable RF-ID tag.

42. The apparatus of claim 40, wherein the transponder alters the frequency of the source signal.

43. The apparatus of claim 40, wherein the transponder alters the time of the source signal.

44. The apparatus of claim 40, wherein the transponder alters the time and frequency of the source signal.

45. The apparatus of claim 40, wherein the transponder Doppler modulates the signal and alters one or both of the time and frequency of the source signal.