Moving-entity detection

• US 8,362,942 B2
• Filed: 02/24/2009
• Issued: 01/29/2013
• Est. Priority Date: 04/14/2005
• Status: Active Grant

• Current Assignee: L3harris Fuzing and Ordnance Systems Incorporated
• Original Assignee: L-3 Communications CyTerra Corporation (L3Harris Technologies, Inc.)
• Inventors: McNeill, James, MacKey, Todd, Dyson, Tim
• Primary Examiner(s): LOBO, IAN J
• Application Number:
  US12/391,940
• Publication Number:
  US 20090262006A1
• Time in Patent Office: 1,435 Days
• Field of Search: 342/22, 342/27, 342/28
• US Class Current: 342/22
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/1113 Local tracking of patients, e.g. in a hospital or private home
• 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 13/584 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 detecting entities based on movement can involve transmission circuitry configured to enable transmission of a stepped-frequency radar signal, an antenna, and receiving circuitry configured to generate data including information associated with frequency and phase shifts between the transmitted signal and the reflections of the transmitted signal. The system also can involve a processor configured to analyze the generated data to determine information associated with a moving object located at a side of a wall different than a side of the wall of which the system is located. The analyzing can involve compensating for the effect of motion of the system on the phase shifts between the transmitted signal and the reflections of the transmitted signal.

Claims

1. A method for determining a motion of a system, 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 an antenna;

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

analyzing the generated data to determine a first apparent phase of an object in the region;

transmitting a second stepped-frequency radar signal through the wall;

detecting reflections of the second transmitted signal with the antenna;

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

analyzing the generated data to determine a second apparent phase of the object;

comparing the first apparent phase of the object to the second apparent phase of the object; and

determining a motion of a system that includes the antenna based on the comparison information associated with a moving object located beyond the second side of the wall, the analyzing including using the determined one or more characteristics of the motion of the transmitted signal and the reflections of the transmitted signal.

2. The method of claim 1 wherein determining the motion of the system includes receiving an indication of the motion of the system from a motion sensor included in the system.

3. The method of claim 2 wherein receiving an indication of the motion of the system from the motion sensor includes receiving information from a global positioning system sensor.

4. The method of claim 2 wherein receiving an indication of the motion of the system from the motion sensor includes receiving information from one or more sensors.

5. The method of claim 4 wherein receiving information from the one or more sensors includes receiving information from a global positioning system (GPS) sensor and from an inertial sensor and sampling one or more outputs of the inertial sensor indicating a current state of acceleration in each of three spatial dimensions.

6. The method of claim 2 wherein generating the data includes generating packets of data that each include information associated with the received indication of the motion of the system and the information associated with frequency and phase shifts.

7. The method of claim 2 further comprising:

using the determined motion of the system to compensate for the effect of the motion by

altering the generated data to reverse the Doppler shift of the detected reflections resulting from the determined motion of the system, and analyzing the altered data to determine information associated with a moving object located beyond the second side of the wall.

8. The method of claim 1 further comprising identifying a phase change of detected reflections of the transmitted signal from stationary objects wherein:

the motion of the system is determined based on the identification of the phase change of detected reflections of the transmitted signal from stationary objects.

9. The method of claim 8 further comprising using the determined motion of the system to compensate for the effect of the motion by

altering the generated data to reverse the Doppler shift of the detected reflections resulting from the motion of the system, and analyzing the altered data to determine the information associated with a moving object located beyond the second side of the wall.

10. The method of claim 1 wherein the motion of the system is determined based on identifying phase changes that indicate a pattern of movement of objects.

11. The method of claim 1 wherein:

transmitting the stepped-frequency radar signal includes beginning transmission of the stepped-frequency radar signal 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 reflections of the transmitted signal with the antenna while the antenna is in motion includes detecting reflections of the transmitted signal during the movement of the antenna from the first system location to the second system location; and

analyzing the generated data includes determining the information associated with the moving object located beyond the second side of the wall based upon the reflections detected during the movement of the antenna from the first system location to the second system location.

12. The method of claim 11 wherein:

generating the data includes generating data for detected reflections which includes information associated with frequency and phase shifts and associated with the motion of the system determined during the detection of reflections of the transmitted signal; 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 the motion of the system.

13. The method of claim 12 wherein:

determining the motion of the system during the detection of reflections of the transmitted signal 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.

14. 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.

15. The method of claim 1 further comprising:

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

generating an altered stepped-frequency radar signal such that the order of the transmitted frequencies is changed or such that one or more of the transmitted frequencies is removed; and

transmitting the altered stepped-frequency radar signal.

16. The method of claim 1 wherein determining the motion of the system includes determining the motion of the antenna.

17. The method of claim 1, further comprising:

adjusting the generated data to account for the determined motion of the system.

18. The method of claim 1, further comprising altering frequency data to account for the determined motion of the system.

19. The method of claim 1, wherein the object comprises a stationary object.

20. The method of claim 1, wherein the object comprises the wall.

21. The method of claim 1, wherein the object comprises multiple objects, the first apparent phase comprises a first apparent phase for each of the multiple objects, the second apparent phase comprises a second apparent phase for each of the multiple objects;

and further comprising;

analyzing each of the phases of the first apparent phase to determine a first pattern of apparent motion of the multiple objects; and

analyzing each of the phases of the second apparent phase to determine a second pattern of apparent motion of the multiple objects, wherein the comparison comprises a comparison of the first and second patterns of motion.

22. The method of claim 1, wherein the transmitted stepped-frequency radar signal and the second transmitted stepped-frequency radar signal are below 4 GHz.

23. A system comprising:

transmission circuitry configured to enable transmission, through a wall to a region, of a stepped-frequency radar signal and a second stepped-frequency radar signal;

an antenna configured to detect reflections of the transmitted signal and reflections of the second transmitted signal;

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

a processor configured to receive the generated data from the receiving circuitry and to;

analyze the generated data to determine a first apparent phase of an object in the region;

analyze the second generated data to determine a second apparent phase of the object;

compare the first apparent phase of the object to the second apparent phase of the object; and

determine a motion of the system based on the comparison.

24. The system of claim 23 wherein the receiving circuitry is a part of the processor.

25. The system of claim 23 further comprising a motion sensor configured to provide an indication of the motion of the system, and wherein,

to generate the data, the receiving circuitry is configured to receive the indication of the motion of the system from the motion sensor.

26. The system of claim 25 wherein the motion sensor is a global positioning system sensor.

27. The system of claim 25 wherein the motion sensor is an inertial sensor.

28. The system of claim 27 wherein the inertial sensor is configured to output a current state of acceleration in each of three spatial dimensions.

29. The system of claim 27 wherein to generate the data, the receiving circuitry is configured to generate packets of data which each include information associated with the received indication of the determined motion of the system along with the information associated with frequency and phase shifts.

30. The system of claim 23 wherein the processor is further configured to use the determined motion of the system to compensate for the effect of the motion by

altering the generated data to reverse the Doppler shift of the detected reflections resulting from the motion of the system, and analyzing the altered data to determine information associated with a moving object located in the region.

31. The system of claim 23 wherein the processor is further configured to use the determined motion of the system to compensate for the effect of the motion by identifying a phase change of detected reflections of the transmitted signal from stationary objects, and

determining the motion of the system based on the identification of the phase change of detected reflections of the transmitted signal from stationary objects.

32. The system of claim 31 wherein, to use the determined motion of the system to compensate for the effect of the motion, the processor is configured to:

alter the generated data to reverse the Doppler shift of the detected reflections resulting from the determined motion of the system; and

analyze the altered data to determine the information associated with a moving object on the side of the wall different than the side of the wall of which the system is located.

33. The system of claim 23 wherein, the motion of the system is determined by identifying phase changes indicative of a pattern of movement of objects.

34. The system of claim 23 wherein:

the transmission circuitry is configured to enable the transmission of the stepped-frequency radar signal to begin at a first system location and to continue during movement of the system from the first system location to a second system location;

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

the processor is configured to determine the information associated with a moving object located at the side of the wall different than the side of the wall of which the system is located based upon the reflections detected during the movement of the system from the first system location to the second system location.

35. The system of claim 34 wherein:

to generate the data, the receiving circuitry is configured to generate data for detected reflections that includes information associated with frequency and phase shifts and information associated with the motion of the system; and

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

36. The system of claim 35 further comprising an inertial sensor configured to determine the motion of the system wherein,

to generate the data, 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.

37. The system of claim 23 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.

38. The system of claim 23 wherein the processor is configured to:

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

enable generation of the altered stepped-frequency radar signal such that the order of the transmitted frequencies is changed or such that one or more of the transmitted frequencies is removed; and

enable the transmission circuitry to transmit the altered stepped-frequency radar signal.

39. The system of claim 23 wherein, to use the motion of the system, the processor is configured to use one or more characteristics of motion of the antenna.