Stabilizing motion in a radar detection system using ultrasonic radar range information

• US 6,909,397 B1
• Filed: 12/10/2003
• Issued: 06/21/2005
• Est. Priority Date: 12/10/2003
• Status: Expired due to Fees

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Greneker, Eugene Ferguson III, Zywicki, Daren Joseph
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US10/732,126
• Publication Number:
  US 20050128123A1
• Time in Patent Office: 559 Days
• Field of Search: 367 87-116, 367/900, 367/901, 367/903, 367/904, 367/910, 367/911, 342/22, 342 25 R- 25 F, 342/27, 342/28, 342 52- 55, 342/59, 342 70- 72, 342 82-103, 342/118, 342/127, 342/128, 342/131, 342/132, 342/134, 342/135, 342/159, 342165-175, 342189-197, 128/204.21, 128/204.22, 128/204.23, 356 401- 515, 356/72, 340/521, 340551-557, 340/435, 600/407, 600/430, 600/529, 600/534, 600/535, 600/536
• US Class Current: 342/173
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• 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 13/862 Combination of radar systems with sonar systems
• CPC Class Codes: G01S 13/888 through wall detection
• CPC Class Codes: G01S 15/08 Systems for measuring distance only indirect measurement G01S15/46

Abstract

One preferred embodiment of the present invention provides a system and method for suppressing motion artifacts introduced by movement of a radar detection system. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. The system includes a Doppler radar module configured to transmit a microwave signal directed towards an object and receive the reflected microwave signals from the object and a living subject positioned behind the object. Also, the system includes a reference module configured to transmit a reference signal towards the object and receive the reflected reference signal from the object. By comparing the two reflected signals from the Doppler radar module and the reference device, a signal processor suppresses motion artifacts generated by movement of the Doppler radar module to identify the presence of the living subject behind the object. Other systems and methods are also provided.

Claims

1. A system for suppressing motion artifacts introduced by movement of a radar detection device, comprising:

a microwave radar module for directing a beam of microwave energy towards an object and for receiving reflected microwave energy comprising a reflected microwave signal from the object;

a reference module for directing a reference beam of energy towards the object and for receiving reference energy comprising a reflected reference signal from the object; and

a signal processor to suppress the motion artifacts in the reflected microwave energy after analyzing the reflected microwave energy and the reflected reference energy.

2. The system of claim 1, wherein the beamwidth of the beam of microwave energy transmitted by the microwave radar module is substantially the same as the beamwidth of the reference beam of energy transmitted by the reference module.

3. The system of claim 1, wherein the microwave radar module operates at a frequency higher than 10 GHz.

4. The system of claim 1, wherein the object is a non-conducting object, the beam of microwave energy transmits through the non-conducting object, and the reference beam of energy does not transmit through the non-conducting object.

5. The system of claim 1, wherein:

the reflected microwave energy further comprises a reflected microwave signal from a living subject positioned behind the object; and

the signal processor detects a respiration signature of the living subject after the motion artifacts introduced by the movement of the radar detection device are suppressed.

6. The system of claim 5, further comprising:

a display unit for indicating that the presence of the living subject positioned behind the object has been detected, wherein the signal processor determines that the living subject has been detected by analyzing the reflected microwave energy after the motion artifacts in the reflected microwave energy have been suppressed.

7. The system of claim 1, wherein:

the microwave radar module directs a continuous beam of microwave energy;

the reference module directs a continuous reference beam of energy; and

the signal processor suppresses the motion artifacts by removing the difference between the reflected microwave energy and the reflected reference energy.

8. The system of claim 7, wherein the reference module directs a continuous reference beam of ultrasonic energy.

9. The system of claim 8, wherein the reference module operates at a frequency that produces substantially the same Doppler shift in air as the microwave radar module produces at an operating frequency of the microwave radar module.

10. The system of claim 1, wherein:

the microwave radar module directs a continuous beam of microwave energy,

the reference module directs a pulsed reference beam of energy; and

the signal processor suppresses the motion artifacts by determining a representation of the reflected microwave signal from the object based on an operating frequency of the microwave radar module and distance information to the object provided by the reference module, the signal processor utilizing the representation to remove the motion artifacts from the reflected microwave energy.

11. The system of claim 10, wherein the representation of the reflected microwave signal is scaled to the operating frequency of the microwave radar module.

12. The system of claim 10, wherein the reference module directs a pulsed reference beam of ultrasonic energy.

13. The system of claim 10, wherein the reference module directs a pulsed reference beam of laser energy.

14. A system for suppressing motion artifacts introduced by movement of a radar detection device, comprising:

a first transmitting means for directing a first beam of microwave energy towards an object;

a second transmitting means for directing a reference beam of energy towards the object;

a first receiving means for receiving reflected microwave energy from the first beam of microwave energy, the reflected microwave energy from the first beam comprising a reflected microwave signal from the object;

a second receiving means for receiving reflected reference energy from the reference beam of energy, the reflected reference energy from the reference beam comprising a reflected reference signal from the object; and

a signal processing means for suppressing the motion artifacts introduced by the movement of the radar detection device by analyzing the reflected microwave energy and the reflected reference energy.

15. The system of claim 14, wherein:

the reflected microwave further comprises a reflected microwave signal from a living subject positioned behind the object; and

the signal processing means detects a respiration signature of the living subject after the motion artifacts are removed from the reflected microwave energy of the first beam.

16. The system of claim 15, further comprising:

a means for indicating that the presence of the living subject positioned behind the object has been detected, wherein the signal processor determines that the subject has been detected by analyzing the reflected microwave energy after the motion artifacts in the reflected microwave energy have been suppressed.

17. The system of claim 14, wherein the object is a non-conducting object, the first beam of microwave energy transmits through the non-conducting object, and the reference beam of energy does not transmit through the non-conducting object.

18. The system of claim 14, wherein the beamwidth of the first beam of microwave energy is substantially the same as the beamwidth of the reference beam of energy.

19. The system of claim 14, wherein the first transmitting means for directing operates at a frequency higher than 10 GHz.

20. The system of claim 14, wherein:

the first transmitting means directs a continuous beam of microwave energy;

the second transmitting means module directs a continuous reference beam of energy; and

the signal processor means suppresses the motion artifacts by removing the difference between the reflected microwave energy and the reflected reference energy.

21. The system of claim 20, wherein the second transmitting means directs a continuous reference beam of ultrasonic energy.

22. The system of claim 21, wherein the second transmitting means operates at a frequency that produces substantially the same Doppler shift in air as the first transmitting means produces at an operating frequency of the first transmitting means.

23. The system of claim 14, wherein:

the first transmitting means directs a continuous beam of microwave energy;

the second transmitting means directs a pulsed reference beam of energy; and

the signal processing means suppresses the motion artifacts by determining a representation of the reflected microwave signal from the object based on an operating frequency of the first transmitting means and distance information to the object provided by the second receiving means, the signal processing means utilizing the representation to remove the motion artifacts from the reflected microwave energy.

24. The system of claim 23, wherein the representation of the reflected microwave signal is scaled to the operating frequency of the first transmitting means.

25. The system of claim 23, wherein the second transmitting means directs a pulsed reference beam of ultrasonic energy.

26. The system of claim 23, wherein the second transmitting means directs a pulsed reference beam of laser energy.

27. A method for suppressing motion artifacts introduced by movement of a radar detection device, comprising the steps of:

transmitting a first beam of microwave energy towards an object;

receiving reflected energy from the first beam of microwave energy, the reflected microwave energy from the first beam comprising a reflected microwave signal from the object;

transmitting a reference beam of energy towards the object;

receiving reflected reference energy from the reference beam of energy, the reflected reference energy from the reference beam comprising a reflected reference signal from the object; and

suppressing the motion artifacts introduced by movement of the radar detection device in the reflected microwave energy.

28. The method of claim 27, wherein the beamwidth of the first beam of microwave energy is substantially the same as the beamwidth of the reference beam of energy.

29. The method of claim 27, wherein the first beam is transmitted at a frequency higher than 10 GHz.

30. The method of claim 27, further comprising the step of:

detecting a respiration signature of a living subject positioned behind the object after the motion artifacts are suppressed, wherein the reflected microwave energy from the first beam further comprises a reflected microwave signal from the living subject.

31. The method of claim 30, further comprising the step of:

indicating that the presence of the living subject positioned behind the object has been detected by analyzing the reflected microwave energy of the first beam after the motion artifacts in the reflected microwave energy of the first beam have been suppressed.

32. The method of claim 27, wherein the object is non-conducting object, the first beam of microwave energy transmits through the non-conducting object, and the reference beam of energy does not transmit through the non-conducting object.

33. The method of claim 27, the suppressing step further comprising the step of:

removing the difference between the reflected microwave energy and the reflected reference energy, wherein the first beam of microwave energy is a continuous beam of microwave energy, and the reference beam of energy is a continuous reference beam of energy.

34. The method of claim 33, wherein the continuous reference beam of energy is a continuous reference beam of ultrasonic energy.

35. The method of claim 34, wherein the continuous reference beam of energy is transmitted at a frequency that produces substantially the same Doppler shift in air as the continuous beam of microwave energy does.

36. The method of claim 27, the suppressing step further comprising the steps of:

obtaining range information on the distance to the object from the reflected reference energy;

generating a representation of the reflected microwave signal from the object using the range information; and

comparing the representation of the reflected microwave signal from the object with the reflected microwave energy from the first beam to isolate a reflected microwave signal from a different object,

wherein the first beam of microwave energy is a continuous beam of microwave energy and the reference beam of energy is a pulsed reference beam of energy.

37. The method of claim 36, wherein the representation of the reflected microwave signal is scaled to the same frequency as the first beam of microwave energy.

38. The method of claim 36, wherein the pulsed reference beam of energy is a pulsed reference beam of ultrasonic energy.

39. The method of claim 36, wherein the pulsed reference beam of energy is a pulsed reference beam of laser energy.