Determining presence and/or physiological motion of one or more subjects within a doppler radar system

• US 20080074307A1
• 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:
  US11/803,653
• Publication Number:
  US 20080074307A1
• Time in Patent Office: Days
• US Class Current: 342/28
• 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 detecting presence and/or physiological motion of at least one subject using a Doppler radar system and determining a number of subjects within range are provided. In one example, the apparatus includes a receiver for receiving a transmitted source signal, the transmitted source signal modulated by at least one subject, logic for mixing the received transmitted signal and a local oscillator signal, and logic for performing a Generalized Likelihood Ratio Test (GLRT) on the mixed signal to determine a number of subjects modulating the signal. Additionally, the receiver may include a quadrature receiver operable for mixing the source signal and the received modulated source signal to generate in-phase (I) and quadrature (Q) data, whereby nulls in the signal are avoided.

Claims

1. Apparatus for detecting physiological motion of one or more subjects, the apparatus comprising:

a receiver for receiving a transmitted source signal, the transmitted source signal modulated by zero, one, or more subjects;

logic for mixing the received transmitted signal and a local oscillator signal; and

logic for performing a hypothesis test on the mixed signal to determine a number of subjects modulating the signal.

2. The apparatus of claim 1, further comprising at least a second receiver for receiving the transmitted signal.

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

4. The apparatus of claim 1, further comprising logic for removing DC offset.

5. The apparatus of claim 1, wherein the logic for performing the hypotheses test comprises a GLRT.

6. The apparatus of claim 1, wherein the logic for performing the hypothesis test is based on an fast Fourier transform.

7. The apparatus of claim 1, further comprising logic for performing a 2D fast Fourier transform.

8. The apparatus of claim 1, wherein the received signal is divided into multiple blocks, each block processed by a frequency transform technique, and the results thereof combined.

9. The apparatus of claim 8, wherein the combined results are used in a hypothesis test to detect the presence of a single subject.

10. The apparatus of claim 8, wherein the combined result is used to separate the heart rate of a subject.

11. The apparatus of claim 8, wherein the combined result is used in a hypothesis test to determine the number of subjects present as 0, 1, 2, or more.

12. The apparatus of claim 1, wherein the hypothesis test is applied before demodulating the signal, on the IQ outputs.

13. The apparatus of claim 12, wherein multiple fast Fourier transforms are applied on the IQ outputs and the result of these combined.

14. The apparatus of claim 13, wherein the result is used in a hypothesis test to detect the presence of a single subject.

15. The apparatus of claim 13, wherein the result is used to separate the heart rate of a subject.

16. The apparatus of claim 12, wherein the received signal is divided into multiple blocks, each block processed by multiple frequency transforms, and the results combined.

17. The apparatus of claim 16, wherein the combined result is used in a hypothesis test to detect the presence of a single subject.

18. The apparatus of claim 16, wherein the combined result is used to separate the heart rate of a subject.

19. The apparatus of claim 16, wherein the combined result is used in a hypothesis test to determine the number of subjects present as 0, 1, 2, or more.

20. A method for detecting physiological motion of multiple subjects, the method comprising the acts of:

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

mixing the received transmitted signal and a local oscillator signal; and

performing a hypothesis test on the mixed signal to determine a number of subjects modulating the signal, wherein the number of subjects may include zero, one, or more subjects.

21. The method of claim 20, further comprising receiving the transmitted signal at two or more antennas.

22. The method of claim 20, further comprising causing transmission of the transmitted signal.

23. The method of claim 20, further comprising removing DC offset from the received signal.

24. The method of claim 20, wherein the hypothesis test comprises a GLRT.

25. The method of claim 20, further comprising performing a 2D fast Fourier transform and peak search.

26. A computer program product comprising computer-readable program code for determining a number of subjects in a Doppler radar system, the product comprising program code for:

performing a generalized likelihood ratio test on a mixed signal of a received transmitted signal modulated by at least one subject and a source signal;

determining a number of subjects modulating the signal.

27. The computer program product of claim 26, wherein the received transmitted signal is received at two or more antennas.

28. The computer program product of claim 26, further comprising program code for causing transmission of the transmitted signal.

29. The computer program product of claim 26, further comprising program code for removing DC offset from the received signal.

30. The computer program product of claim 26, further comprising program code for performing a fast Fourier transform GLRT.

31. The computer program product of claim 26, further comprising program code for performing a 2D fast Fourier transform and peak search.