RANDOM BODY MOVEMENT CANCELLATION FOR NON-CONTACT VITAL SIGN DETECTION

• US 20140330540A1
• Filed: 05/13/2014
• Published: 11/06/2014
• Est. Priority Date: 07/12/2007
• Status: Active Grant

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: LIN, JENSHAN, Li, CHANGZHI, LlU, YA-CHI
• Granted Patent: US 9,477,812 B2
• Time in Patent Office: Days
• US Class Current: 702/194
• 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 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/536 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems
• CPC Class Codes: G01S 7/354 Extracting wanted echo-signals Doppler systems G01S13/50
• CPC Class Codes: G01S 7/40 Means for monitoring or calibrating
• CPC Class Codes: G06F 17/14 Fourier, Walsh or analogous domain transformations , e.g. Laplace, Hilbert, Karhunen-Loeve, transforms for correlation function computation G06F17/156; spectrum analysers G01R23/16
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: G16H 80/00 ICT specially adapted for facilitating communication between medical practitioners or patients, e.g. for collaborative diagnosis, therapy or health monitoring

Abstract

A method and system for cancelling body movement effect for non-contact vital sign detection is described. The method begins with sending on a first electromagnetic wave transceiver a first electromagnetic signal with a first frequency to a first side of a body, such as a person or animal. Simultaneously using a second electromagnetic wave transceiver a second electromagnetic signal is sent with a second frequency to a second side of a body, wherein the first frequency and the second frequency are different frequencies. A first reflected electromagnetic signal reflected back in response to the first electromagnetic wave on the first transceiver is received and a first baseband complex signal is extracted. Likewise a second reflected electromagnetic signal reflected back in response to the second electromagnetic wave on the second transceiver is received and a second baseband complex signal is extracted. The first baseband complex signal is mathematically combined with the second baseband complex signal to cancel out a Doppler frequency drift therebetween to yield a periodic Doppler phase effect.

Claims

1. A method for cancelling body movement effect for non-contact vital sign detection, the method comprising:

sending at least two electromagnetic signals comprising a first electromagnetic signal with a first frequency to a first side of a body from a first electromagnetic wave transceiver and a second electromagnetic signal with a second frequency to a second side of a body from a second electromagnetic wave transceiver;

receiving at least a first reflected electromagnetic signal reflected back in response to the first electromagnetic wave on the first transceiver, and extracting out a first baseband complex signal therefrom and receiving at least a second reflected electromagnetic signal reflected back in response to the second electromagnetic wave on the second transceiver, and extracting out a second baseband complex signal therefrom;

mathematically combining the first baseband complex signal with the second baseband complex signal to cancel out a Doppler frequency drift therebetween to yield a periodic Doppler phase effect.

2. The method of claim 1, further comprising:

extracting at least one of respiration rate and heart rate from the periodic Doppler phase effect

3. The method of claim 2, further comprising:

sending the at least one of respiration rate and heart rate from the periodic Doppler phase effect which has been extracted to a display.

4. The method of claim 1, wherein the first frequency of wavelength λ

₁ and the second frequency of wavelength λ

₂ are close to each other so that (λ

₁≈

λ

₂≈

λ

) and the mathematically combining the first baseband with the second baseband by complex signal demodulation is expressed by

5. The method of claim 4, wherein a DC offset in at least one of the first baseband and the second baseband cannot be accurately calibrated.

6. The method of claim 1, wherein the first frequency of wavelength λ

₁ and the second frequency of wavelength λ

₂ are close to each other so that (λ

₁≈

λ

₂≈

λ

) and the mathematically combining the first base band with the second based band by arctangent demodulation is expressed by

7. The method of claim 6, wherein a DC offset in the first baseband and the second baseband can be accurately calibrated.

8. The method of claim 1, wherein the first electromagnetic wave transceiver and the second electromagnetic wave transceiver are anyone of:

5.8 GHz quadrature radar transceivers; and

24 GHz quadrature radar transceivers.

9. A system for cancelling body movement effect for non-contact vital sign detection, the system comprising:

at least a first electromagnetic wave transceiver and at least a second electromagnetic wave transceiver,

wherein first electromagnetic wave transceiver sends on a first electromagnetic signal with a first frequency to a first side of a body and for receiving a first reflected electromagnetic signal reflected back in response to the first electromagnetic wave on the first transceiver, and extracting out a first baseband complex signal therefrom;

wherein the second electromagnetic wave transceiver for sending a second electromagnetic signal with a second frequency to a second side of a body, wherein the first frequency and the second frequency are different frequencies and for receiving a second reflected electromagnetic signal reflected back in response to the second electromagnetic wave on the second transceiver, and extracting out a second baseband complex signal therefrom;

a processor for mathematically combining the first baseband complex signal with the second baseband complex signal to cancel out a Doppler frequency drift therebetween to yield a periodic Doppler phase effect.

10. The system of claim 9, further comprising:

means for extracting at least one of respiration late and heart ate from the periodic Doppler phase effect

11. The system of claim 10, further comprising:

a display for displaying at least one of respiration rate and heart rate from the periodic Doppler phase effect which has been extracted.

12. The system of claim 9, wherein the first frequency of wavelength λ

₁ and the second frequency of wavelength λ

₂ are close to each other so that (λ

₁≈

λ

₂≈

λ

) and the mathematically combining the first baseband with the second baseband by complex signal demodulation is expressed by

13. The system of claim 12, wherein a DC offset in at least one of the first baseband and the second baseband cannot be accurately calibrated.

14. The system of claim 9, wherein the first frequency of wavelength λ

₁ and the second frequency of wavelength λ

₂ are close to each other so that (λ

₁≈

λ

₂≈

λ

) and the mathematically combining the first base band with the second based band by arctangent demodulation is expressed by

15. The system of claim 14, wherein a DC offset in the first baseband and the second baseband can be accurately calibrated.

16. The system of claim 9, wherein the first electromagnetic wave transceiver and the second electromagnetic wave transceiver are anyone of:

5.8 GHz quadrature radar transceivers; and

24 GHz quadrature radar transceivers.