Systems and Methods for Detecting Movement of a Target

• US 20100241009A1
• Filed: 03/19/2010
• Published: 09/23/2010
• Est. Priority Date: 03/20/2009
• Status: Active Grant

• Current Assignee: Wright State University
• Original Assignee: Wright State University
• Inventors: Petkie, Douglas T.
• Granted Patent: US 9,164,168 B2
• Time in Patent Office: Days
• US Class Current: 600/484
• 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 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: G01S 13/50 Systems of measurement based on relative movement of target
• CPC Class Codes: G01S 13/583 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 7/35 Details of non-pulse systems

Abstract

A system is disclosed for wirelessly detecting movement of a target. The system comprises a reference oscillator, a transmitter, a receiver, a demodulator, and a processor, wherein: the reference oscillator generates references frequencies for the transmitter, the receiver, and the demodulator; the transmitter generates a continuous-wave signal at a frequency based on the transmitter reference frequency and wirelessly transmits it to the target; the receiver wirelessly receives a reflected signal from the target having a phase angle corresponding to movement of the target and converts the reflected signal into an intermediate frequency signal based on the receiver reference frequency; the demodulator demodulates the intermediate frequency signal into an in-phase component and a quadrature component; and the processor converts the in-phase component and the quadrature component into a movement signal corresponding to movement of the target.

Claims

1. A system for wirelessly detecting movement of a target, the system comprising a reference oscillator, a transmitter, a receiver, a demodulator, and a processor, wherein:

the reference oscillator is electrically coupled to the transmitter, the receiver, and the demodulator and generates a transmitter reference frequency, a receiver reference frequency, and a demodulator reference frequency;

the transmitter generates a continuous-wave signal at a frequency based on the transmitter reference frequency and wirelessly transmits the continuous-wave signal to the target;

the receiver wirelessly receives a reflected signal from the target, wherein the reflected signal comprises the continuous-wave signal reflected by the target, and wherein a phase angle of the reflected signal corresponds to movement of the target;

the receiver converts the reflected signal into an intermediate frequency signal based on the receiver reference frequency;

the demodulator is electrically coupled to the receiver and demodulates the intermediate frequency signal into an in-phase component and a quadrature component based on the phase angle of the reflected signal, wherein the demodulator uses the demodulator reference frequency to demodulate the intermediate frequency signal; and

the processor is electrically coupled to the demodulator and converts the in-phase component and the quadrature component into a movement signal corresponding to movement of the target.

2. The system of claim 1, wherein the reference oscillator has a frequency of approximately 100 MHz.

3. The system of claim 1, wherein the continuous-wave signal operates at approximately 228 GHz.

4. The system of claim 1, wherein the intermediate frequency signal operates at approximately 2.4 GHz.

5. The system of claim 1, wherein the target is a human, and movement of the target includes movement due to respiration and movement due to a heartbeat.

6. The system of claim 5, wherein the processor further determines a respiration rate of the target based on the movement signal.

7. The system of claim 5, wherein the processor further determines a heartbeat rate of the target based on the movement signal.

8. The system of claim 1, wherein the target is an airplane, and movement of the target is vibration of the airplane.

9. The system of claim 1, wherein the receiver comprises a heterodyne receiver capable of multiplying the reflected signal with the receiver reference frequency.

10. The system of claim 1, further comprising a lock-in amplifier, wherein the lock-in amplifier is electrically coupled to the demodulator and the processor such that the lock-in amplifier increases sensitivity of the in-phase component and the quadrature component based on amplitude modulation of the continuous-wave signal.

11. A system for wirelessly detecting movement of a target, the system comprising a transmitter, a frequency modulator, a beam splitter, a reflector, an interferometer, and a processor, wherein:

the transmitter generates a continuous-wave signal and wirelessly transmits the continuous-wave signal to the beam splitter;

the frequency modulator is electrically coupled to the transmitter and modulates the continuous-wave signal between a first frequency and a second frequency;

the beam splitter divides the continuous-wave signal into a first signal and a second signal, wherein the first signal is wirelessly directed toward the target and the second signal is wirelessly directed toward the reflector;

the interferometer wirelessly receives the first signal reflected from the target and wirelessly receives the second signal reflected from the reflector, wherein a phase angle of the first signal reflected from the target corresponds to movement of the target;

the interferometer combines the first signal reflected from the target and the second signal reflected from the reflector and produces an electrical signal corresponding to a magnitude of the phase angle between the first signal reflected from the target and the second signal reflected from the reflector; and

the processor is electrically coupled to the frequency modulator and the electrical signal such that the processor determines movement of the target based on the electrical signal when the continuous-wave signal is transmitted at the first frequency and when the continuous-wave signal is transmitted at the second frequency.

12. A method for wirelessly detecting movement of a target, the method comprising:

generating a reference oscillator having a reference frequency;

generating a continuous-wave signal based on the reference frequency;

wirelessly transmitting the continuous-wave signal to the target;

wirelessly receiving a reflected signal from the target, wherein the reflected signal comprises the continuous-wave signal reflected by the target, and wherein a phase angle of the reflected signal corresponds to movement of the target;

converting the reflected signal into an intermediate frequency signal, wherein converting the reflected signal is based on the reference frequency;

demodulating the intermediate frequency signal into an in-phase component and a quadrature component based on the phase angle of the reflected signal, wherein demodulating the intermediate frequency signal is based on the reference frequency; and

generating a movement signal corresponding to movement of the target, wherein the movement signal is based on the in-phase component and the quadrature component.

13. The method of claim 12, wherein the reference frequency is approximately 100 MHz.

14. The method of claim 12, wherein the continuous-wave signal operates at approximately 228 GHz.

15. The method of claim 12, wherein the intermediate frequency signal operates at approximately 2.4 GHz.

16. The method of claim 12, wherein the target is a human, and movement of the target includes movement due to respiration and movement due to a heartbeat.

17. The method of claim 16, further determining a respiration rate of the target based on the movement signal.

18. The method of claim 16, further determining a heartbeat rate of the target based on the movement signal.

19. The method of claim 12, wherein the target is an airplane, and movement of the target is vibration of the airplane.

20. The method of claim 12, further comprising amplitude modulating the continuous-wave signal in order to increase sensitivity of the in-phase component and the quadrature component.