Methods and apparatus for adaptive motion compensation to remove translational movement between a sensor and a target

• US 9,348,021 B2
• Filed: 03/14/2013
• Issued: 05/24/2016
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Wallace, Aaron C.
• Primary Examiner(s): Sotomayor, John B
• Assistant Examiner(s): WINDRICH, MARCUS E
• Application Number:
  US13/826,683
• Publication Number:
  US 20160061946A1
• Time in Patent Office: 1,167 Days
• Field of Search: 342159-164
• US Class Current: 1/1
• CPC Class Codes: G01S 13/18 wherein range gates are used
• CPC Class Codes: G01S 13/5242 with means for platform motion or scan motion compensation, e.g. airborne MTI
• CPC Class Codes: G01S 13/5244 Adaptive clutter cancellation specially adapted for airborne MTI, G01S13/5242
• CPC Class Codes: G01S 7/414 Discriminating targets with respect to background clutter

Abstract

Methods and apparatus for performing adaptive motion compensation to remove translational movement between a sensor and a target using data from the sensor. After whitening, data can be processed to select a target and focus frequency components. Dynamic sliding window processing can be performed on processed time domain data to estimate an instantaneous range rate for the target.

Claims

1. A method, comprising:

performing adaptive motion compensation to remove translational movement between a sensor and a target using data from the sensor by;

performing, using a computer processor, clutter removal from the data using a whitener;

using the whitened data to select a target for which adaptive motion compensation should be performed;

using weighting in the Doppler domain to reduce frequency components for data for the selected target;

transforming the weighted Doppler domain data to time domain data; and

performing dynamic sliding window processing on the time domain data to estimate an instantaneous range rate for the target.

2. The method according to claim 1, further including centering the window on a time of a pulse for which the instantaneous range rate is computed.

3. The method according to claim 1, further including adaptively determining a size of the window based upon coherence of the data.

4. The method according to claim 3, further including, for target range cells above a coherence threshold, computing a phase gradient.

5. The method according to claim 4, further including converting the phase gradient to the instantaneous range rate.

6. The method according to claim 1, further including using a single pulse repetition frequency (PRF) for the adaptive motion compensation processing.

7. The method according to claim 1, further including performing clutter estimation.

8. The method according to claim 7, wherein the clutter estimation includes land clutter or sea clutter determination.

9. The method according to claim 7, wherein performing the clutter estimation further includes using a concavity of a clutter lag profile and/or distance in frequency of a measured clutter peak from an expected clutter peak, wherein the lag profile is computed from augment cells.

10. The method according to claim 1, wherein the sensor forms part of a radar system having an antenna secured to an airborne or space-based platform.

11. The method according to claim 10, further including receiving radar system parameters comprising integration time and smoothing filter gain.

19. The method according to claim 1, wherein the sensor and target are moving.

20. The method according to claim 1, further including determining the adaptive motion compensation on each pulse received by the sensor.

12. An article, comprising:

a computer readable medium containing stored, non-transitory instructions that enable a machine to perform;

performing adaptive motion compensation to remove translational movement between a sensor and a target using data from the sensor by;

performing, using a computer processor, clutter removal from the data using a whitener;

using the whitened data to select a target for which adaptive motion compensation should be performed;

using weighting in the Doppler domain to reduce frequency components for data for the selected target;

transforming the weighted Doppler domain data to time domain data; and

performing dynamic sliding window processing on the time domain data to estimate an instantaneous range rate for the target.

13. The article according to claim 12, further including instructions for centering the window on a time of a pulse for which the instantaneous range rate is computed.

14. The article according to claim 12, further including instructions for adaptively determining a size of the window based upon coherence of the data.

15. The article according to claim 14, further including, for target range cells above a coherence threshold, instructions for computing a phase gradient.

16. The article according to claim 15, further including instructions for converting the phase gradient to the instantaneous range rate.

17. The article according to claim 12, further including performing clutter estimation.

18. A system, comprising:

a sensor to illuminate an area;

an antenna to receive signal return from the area;

a clutter removal module to remove clutter from the signal return using a whitener;

a target selection module to receive the clutter-removed data and to select a target for which adaptive motion compensation should be performed;

a weighting module to use weighting in the Doppler domain to reduce frequency components for data for the selected target;

a Doppler frequency module to perform Doppler frequency domain processing on the weighted target data; and

a sliding window module to process the Doppler frequency domain data transformed to time domain data to estimate an instantaneous range rate for the target for removing translation movement between the sensor and the target.