Moving-entity detection

• US 9,063,232 B2
• Filed: 02/24/2009
• Issued: 06/23/2015
• Est. Priority Date: 04/14/2005
• Status: Active Grant

• Current Assignee: L3harris Fuzing and Ordnance Systems Incorporated
• Original Assignee: L-3 Communications Security & Detection Systems, Inc. (Leidos Holdings, Inc.)
• Inventors: McNeill, James, Mackey, Todd, Dyson, Tim
• Primary Examiner(s): Lobo, Ian J
• Application Number:
  US12/391,909
• Publication Number:
  US 20090262005A1
• Time in Patent Office: 2,310 Days
• Field of Search: 342/22, 342/27, 342/28
• US Class Current: 1/1
• CPC Class Codes: G01S 13/38 wherein more than one modulation frequency is used
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• 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 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/888 through wall detection
• CPC Class Codes: G01S 13/9029 specially adapted for moving target detection within a single SAR image or within multiple SAR images taken at the same time
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
• CPC Class Codes: G01S 7/038 Feedthrough nulling circuits
• CPC Class Codes: G01S 7/35 Details of non-pulse systems
• CPC Class Codes: G01S 7/4004 of parts of a radar system

Abstract

A system and method for enabling transmission of a stepped-frequency radar signal can involve a first antenna and a second antenna. The system can also involve receiving circuitry configured to receive detected reflections from the antennas and to generate data including information associated with frequency and phase shifts. The system can further involve a processor configured to receive the generated data from the receiving circuitry and to analyze the generated data to determine information associated with a moving object located at a side of a wall opposite to the system by differentiating reflections of the transmitted signal detected with the first antenna from reflections of the transmitted signal detected with the second antenna.

Claims

1. A method for detecting entities, the method comprising:

transmitting a stepped-frequency radar signal through a wall to a region on an opposite side of the wall;

detecting reflections of the transmitted signal with a first antenna;

detecting reflections of the transmitted signal with a second antenna that is spaced from the first antenna and oriented in substantially the same direction as the first antenna, the first antenna and second antenna being enclosed in a handheld housing;

generating data including information associated with frequency and phase shifts between the reflections of the transmitted signal detected with the first antenna and the second antenna; and

analyzing the generated data to determine a location of a moving entity located in the region, the analysis including detecting the moving entity based on a Doppler shift of reflections of the transmitted signal associated with the moving entity exceeding a high-pass filter cutoff, and determining the location of the moving entity based on the information associated with the phase shifts between the reflections of the transmitted signal detected with the first antenna and the second antenna.

2. The method of claim 1, further comprising:

detecting the reflections of the transmitted signal with a third antenna, the third antenna being spaced along an axis that is perpendicular to an axis between the first antenna and the second antenna, and the third antenna being oriented in substantially the same direction as the first antenna and the second antenna.

3. The method of claim 2 wherein:

generating the data includes generating data associated with frequency and phase shifts between the transmitted signal and the reflections of the transmitted signal detected with the first, second, and third antennas; and

differentiating the reflections of the transmitted signal includes using differences between the phase shift of reflections as detected with the first, second, and third antennas to determine a location of the moving entity.

4. The method of claim 3 further comprising causing presentation of an indication of the determined location of the moving object.

5. The method of claim 2, wherein the second antenna is spaced from the first antenna to form a first interferometric pair, and

wherein the third antenna is spaced from the first antenna to form a second interferometric pair.

6. The method of claim 5, wherein:

generating the data includes generating interferometric measurements from the reflections of the transmitted signal detected with the first, second, and third antennas to determine arrival angle information related to the reflections; and

analyzing the generated data includes determining, based on the interferometiric measurements, a location of the moving entity in three dimensional space.

7. The method of claim 1 wherein transmitting the stepped-frequency radar signal through the wall includes:

transmitting a first stepped-frequency radar signal; and

concurrently transmitting a second stepped-frequency radar signal.

8. The method of claim 7 wherein:

transmitting the first stepped-frequency radar signal includes transmitting the first stepped-frequency radar signal with the first antenna; and

concurrently transmitting the second stepped-frequency radar signal includes concurrently transmitting the second stepped-frequency radar signal with the second antenna.

9. The method of claim 1 wherein:

transmitting the stepped-frequency radar signal includes beginning transmission of the stepped-frequency radar signal with a system at a first system location and moving the system during transmission of the stepped-frequency radar signal from the first system location to a second system location;

detecting the reflections of the transmitted signal includes detecting reflections of the transmitted signal during the movement of the system from the first system location to the second system location; and

analyzing the generated data includes determining the location of the moving entity based upon the reflections detected during the movement of the system from the first system location to the second system location.

10. The method of claim 9 further comprising determining system motion as reflections of the transmitted signal are detected during the movement of the system from the first system location to the second system location, wherein:

generating the data includes generating data for detected reflections which includes information associated with frequency and phase shifts and associated with a corresponding system motion as determined when the reflection was detected; and

analyzing the generated data includes generating a synthetic aperture radar image using the data including information associated with frequency and phase shifts and associated with a corresponding system motion.

11. The method of claim 10 wherein:

determining the system motion as reflections of the transmitted signal are detected during the movement of the system includes sampling output of an inertial sensor within the system; and

generating the data includes generating a packet of data for reflections received at each of multiple system locations between the first and second system locations, each packet including the information associated with frequency and phase shifts and output of the sampled inertial sensor at the time the reflection was detected.

12. The method of claim 1 further comprising:

identifying a transmit-to-receive leakage signal resulting from the transmission of the stepped-frequency radar signal;

generating a cancellation waveform configured to remove effects of the identified transmit-to-receive leakage signal; and

using the generated cancellation waveform to remove effects of transmit-to-receive leakage signal of subsequent transmissions.

13. The method of claim 1 further comprising:

after transmitting the stepped-frequency radar signal, determining the stepped-frequency radar signal should be altered; and

transmitting an altered stepped-frequency radar signal based upon the determination that the stepped-frequency radar signal should be altered.

14. The method of claim 13 further comprising generating the altered stepped-frequency radar signal, the altered stepped-frequency radar signal comprising fewer transmitted frequencies than the transmitted stepped-frequency radar signal.

15. The method of claim 13 further comprising generating the altered stepped-frequency radar signal, the altered stepped-frequency radar signal having the order of the transmitted frequencies changed.

16. The method of claim 1, further comprising detecting reflections of the transmitted signal with a rear-facing antenna.

17. The method of claim 1, wherein frequencies of the transmitted stepped-frequency radar signal are less than 4 GHz.

18. The method of claim 1, further comprising determining, based on the generated data, a location of a non-moving entity by identifying at least one vital sign of the non-moving entity.

19. The method of claim 1, wherein the second antenna is spaced from the first antenna to form a first interferometric pair.

20. A system for detecting entities, the system comprising:

transmission circuitry configured to enable transmission of a stepped-frequency radar signal;

a first antenna configured to detect reflections of the transmitted signal;

a second antenna configured to detect reflections of the transmitted signal, the second antenna being spaced from the first antenna and oriented in substantially the same direction as the first antenna, the first antenna and second antenna being enclosed in a handheld housing;

receiving circuitry configured to detect reflections from the first and second antennas and to generate data including information associated with frequency and phase shifts between the reflections of the transmitted signal detected with the first antenna and with the second antenna; and

a processor configured to;

analyze the generated data to detect a moving entity located at a side of a wall opposite to the system based on determining that a Doppler shift of reflections of the transmitted signal associated with the moving entity exceed a high-pass filter cutoff, and

determining a location of the moving entity based on the information associated with the phase shifts between the reflections of the transmitted signal detected with the first antenna and the second antenna.

21. The system of claim 20 wherein the receiving circuitry is a part of the processor.

22. The system of claim 20 further comprising:

a third antenna configured to detect reflections of the transmitted signal, the third antenna being spaced along an axis that is perpendicular to an axis between the first antenna and the second antenna, and the third antenna being oriented in substantially the same direction as the first antenna and the second antenna.

23. The system of claim 22 wherein:

the receiving circuitry is configured to receive the detected reflections from the third antenna and to generate data associated with frequency and phase shifts between the transmitted signal and the reflections of the transmitted signal detected with the first, second, and third antennas; and

the processor is configured to differentiate reflections of the transmitted signal based on differences between the phase shift of reflections as detected with the first, second, and third antennas to determine the location of the moving entity.

24. The system of claim 23 wherein the processor is configured to cause presentation of an indication of the determined location of the moving object.

25. The system of claim 20 wherein the transmission circuitry is configured to enable transmission of a first stepped-frequency radar signal and a second stepped-frequency radar signal concurrently.

26. The system of claim 25 further comprising:

a first transmit antenna coupled to the transmission circuitry; and

a second transmit antenna coupled to the transmission circuitry,

wherein to enable transmission of the first and second stepped-frequency radar signals concurrently, the transmission circuitry is configured to enable the concurrent transmission of the first stepped-frequency radar signal with the first transmit antenna and the second stepped-frequency signal with the second transmit antenna.

27. The system of claim 20 wherein:

the receiving circuitry is configured to receive the detected reflections of the transmitted signal during movement of the system from a first system location to a second system location; and

the processor is configured to determine the location of the moving entity located at the side of the wall opposite to the system based upon the reflections detected during the movement of the system from the first system location to the second system location.

28. The system of claim 27 further comprising a motion sensor configured to determine system motion as reflections of the transmitted signal are detected during the movement of the system from the first system location to the second system location, wherein:

the receiving circuitry is configured to generate data for detected reflections which includes information associated with frequency and phase shifts and information associated with a corresponding system motion as determined by the motion sensor when the reflection was detected; and

the processor is configured to generate a synthetic aperture radar image using the data including information associated with frequency and phase shifts and information associated with a corresponding system motion.

29. The system of claim 28 wherein:

the motion sensor is one or more of an inertial sensor or a global positioning system (GPS) sensor; and

to generate data for detected reflections which includes a corresponding system motion, the receiving circuitry is configured to sample output of the inertial sensor and to generate a packet of data for reflections received at multiple system locations between the first and second system locations, each packet including the information associated with frequency and phase shifts and output of the sampled inertial sensor at the time the reflection was detected.

30. The system of claim 20 wherein the processor is configured to:

identify a transmit-to-receive leakage signal resulting from the transmission of the stepped-frequency radar signal;

generate a cancellation waveform configured to remove effects of the identified transmit-to-receive leakage signal; and

use the generated cancellation waveform to remove effects of transmit-to-receive leakage signal of subsequent transmissions.

31. The system of claim 20 wherein the processor is configured to:

after the transmission of the stepped-frequency radar signal, determine the stepped-frequency radar signal should be altered; and

enable the transmission circuitry to transmit an altered stepped-frequency radar signal based upon the determination that the stepped-frequency radar signal should be altered.

32. The system of claim 31 wherein the processor is configured to enable generation of the altered stepped-frequency radar signal, the altered stepped-frequency radar signal having one or more of the transmitted frequencies removed.

33. The system of claim 31 wherein the processor is configured to enable generation of the altered stepped-frequency radar signal, the altered stepped-frequency radar signal having the order of the transmitted frequencies changed.

34. The system of claim 20, further comprising a rear-facing antenna.

35. The system of claim 20 wherein:

the first antenna is connected to a transceiver; and

to enable transmission of the stepped-frequency radar signal, the transmission circuitry is configured to enable transmission of the stepped-frequency radar signal with the first antenna.

36. The system of claim 20, wherein the processor is further configured to determine, based on the generated data, a location of a non-moving entity by identifying at least one vital sign of the non-moving entity.

37. A device comprising:

a handheld housing;

a transmit antenna configured to transmit a radar signal, the radar signal comprising one or more frequencies that penetrate a barrier;

a plurality of receive antennas configured to detect reflections of the transmitted signal, each of the plurality of antennas being distinct from each other, located in the handheld housing, and oriented in substantially the same direction; and

an electronic processor coupled to an electronic storage, the electronic storage comprising instructions, that when executed, cause the processor to analyze the detected reflections of the transmitted signal to determine, based on the analyzed detected reflections, a location of a moving entity on a side of the barrier that is opposite to a side of the barrier where the device is located, the analysis including;

detecting the moving entity based on determining that a Doppler shift of reflections of the transmitted signal associated with the moving entity exceed a high-pass filter cutoff, and

locating the moving entity based on phase shifts between reflections detected by each of the antennas.

38. The device of claim 37, further comprising a rear-facing antenna configured to detect reflections of the transmitted signal.

39. The device of claim 37, wherein the housing at least partially encloses the transmit antenna, the plurality of receive antennas, the electronic processor, and the electronic storage.

40. The device of claim 37, further comprising a display on the housing, and wherein the electronic storage further comprises instructions that cause the processor to present the location of the moving entity on the display.

41. The device of claim 37, wherein the moving entity is a person and the electronic storage further comprises instructions that cause the processor to determine, based on the analyzed detected reflections, one or more of a cardio-pulmonary function of the person, voluntary motion of the person, involuntary motion of the person, a heartbeat of the person, respiration of the person, or blood flow in the person.

42. The device of claim 37, wherein the determined location is relative to a second object having a known location.

43. The device of claim 37, wherein the determined location is an absolute position of the moving entity.

44. The device of claim 37, wherein the electronic storage further comprises instructions to cause the processor to identify the moving entity.

45. The device of claim 44, further comprising a display on the housing, and wherein the electronic storage further comprises instructions to cause the processor to present the location of the moving entity on the display with a display style that indicates that the moving entity has been identified.

46. The device of claim 44, wherein the moving entity is identified by scanning an RFID tag on the object.

47. The device of claim 37, wherein the device is configured to communicate with a second device, the second device comprising:

a housing;

a transmit antenna configured to transmit a radar signal;

a receive antenna configured to detect reflections of the transmitted signal; and

an electronic processor coupled to an electronic storage.

48. The device of claim 37, wherein the housing is configured to be held in a hand of a human operator.

49. A device comprising:

a handheld housing;

a transmit antenna configured to transmit a radar signal, the radar signal comprising one or more frequencies sufficient penetrate a wall;

a plurality of receive antennas configured to detect reflections of the transmitted signal, each of the plurality of antennas being distinct from each other, located in the handheld housing, and oriented in substantially the same direction;

an electronic processor comprising a first signal path adapted to detect and locate one or more moving entities by analyzing the detected reflections of the transmitted signal, the analysis including;

detecting the one or more moving entities based on filtering out non-moving entities and determining that a Doppler shift of reflections of the transmitted signal associated with each moving entity exceed a high-pass filter cutoff, and

locating the one or more moving entities based on phase shifts between reflections detected by each of the antennas;

a second signal path adapted to determine locations one or more non-moving entities by analyzing detected reflections of the transmitted signal, the analysis including identifying vital signs of each non-moving entity; and

a display adapted to receive from the electronic processor and present at least the locations of the one or more non-moving entities.