Higher order processing for synthetic aperture radar (SAR)

• US 9,261,593 B1
• Filed: 03/13/2013
• Issued: 02/16/2016
• Est. Priority Date: 03/13/2013
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Mountcastle, Paul D., Bachmann, Svetlana M.
• Primary Examiner(s): BYTHROW, PETER M
• Application Number:
  US13/799,837
• Time in Patent Office: 1,070 Days
• Field of Search: 342/25.R, 342/25.A, 342/25.B, 342/25.C, 342/25.D, 342/25.E, 342/25.F, 342/89, 342/90, 342160-162, 342/175, 342/189
• US Class Current: 1/1
• 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 13/9029 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 13/9088 Circular SAR [CSAR, C-SAR]
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals
• CPC Class Codes: G01S 7/41 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/411 Identification of targets based on measurements of radar reflectivity G01S7/415 takes precedence
• CPC Class Codes: G01S 7/412 based on a comparison between measured values and known or stored values
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

A method for processing received return signals in a visual synthetic aperture radar (ViSAR) system is provided. The method includes receiving a plurality of pulsed radar return signals over a time period corresponding to a plurality of data frames. From this data, processing is performed to generate a SAR image for each single data frame of the plurality of data frames. In parallel, the radar pulses used to form the image frames are buffered into a longer pulse sequence that is used to perform the detection processing, including identifying targets as having characteristics associated with one or more predetermined motion classes according to phase changes sensed between data frames. A visual indication of targets associated with a predetermined motion class is generated, and overlaid onto one of the SAR images.

Claims

1. A method for processing received return signals in a synthetic aperture radar (SAR) system, including:

receiving, with a receiver of the SAR system, a plurality of pulsed radar return signals over a time period corresponding to a plurality of data frames;

with at least one processor of the SAR system;

processing the received return signals to generate a SAR image for each of the single data frames;

processing a plurality of the single data frames, the processing including identifying targets as having characteristics associated with one or more predetermined motion classes according to phase changes sensed between data frames; and

generating, with a display coupled to the at least one processor, a visual indication of targets associated with a predetermined motion class, and

overlaying the visual indication of targets associated with a predetermined motion class onto one of the SAR images,

wherein each of the one or more motion classes is predefined by a respective one or more parametric models, each model representing a discrete type of motion stored in a memory device.

2. The method of claim 1, wherein the plurality of data frames comprise range-velocity data.

3. The method of claim 1, wherein the step of identifying targets having characteristics associated with one or more predetermined motion classes includes determining acceleration characteristics for each of the identified targets based on the plurality of data frames.

4. The method of claim 1, further comprising the step of displaying the SAR image with the overlaid visual indication of targets associated with a predetermined motion class to a user.

10. The method of claim 1, wherein the step of identifying targets having characteristics associated with one or more predetermined motion classes includes determining the probability that an identified target matches one or more of the predetermined motion classes.

11. The method of claim 10, wherein the step of determining the probability that an identified target matches one or more of the predetermined motion classes includes the step of convolving a calculated conditional probability function with a predetermined class conditional probability function.

5. A system for processing received return signals in a synthetic aperture radar (SAR) system, including:

a transmitter for transmitting a plurality of pulsed radar signals;

a receiver for receiving reflected return signals from the plurality of pulsed radar return signals over a time period corresponding to a plurality of data frames;

at least one processor configured to;

generate a SAR image for each of the single data frames;

process a plurality of the single data frames, the processing including identifying targets as having characteristics associated with one or more predetermined motion classes according to phase changes sensed between data frames, and

a memory device,

wherein each of the one or more motion classes is predefined by a respective one or more parametric models, each model representing a discrete type of motion stored in the memory device.

6. The system of claim 5, wherein the processor is further configured to:

generate a visual indication of targets associated with a predetermined motion class, and

overlay the visual indication of targets associated with a predetermined motion class onto one of the SAR images.

7. The system of claim 6, further comprising a display coupled to the processor, wherein the processor is further configured to display one of the SAR images and the visual indications of targets associated with a predetermined motion class to a user.

8. The system of claim 5, wherein the plurality of data frames comprise range-velocity data.

9. The system of claim 5, wherein the processor is further configured to determine acceleration characteristics for each of the identified targets based on the plurality of data frames.

12. The system of claim 5, wherein identifying targets having characteristics associated with one or more predetermined motion classes includes determining the probability that an identified target matches one or more of the predetermined motion classes.

13. The system of claim 12, wherein determining the probability that an identified target matches one or more of the predetermined motion classes includes convolving a calculated conditional probability function with a predetermined class conditional probability function.