Subaperture clutter filter with CFAR signal detection

Patent metadata

Field	Value
Publication number	US-9429644-B1
Application number	US-201314052901-A
Country	US
Kind code	B1
Filing date	Oct 14, 2013
Priority date	Oct 14, 2013
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

The various technologies presented herein relate to the determination of whether a received signal comprising radar clutter further comprises a communication signal. The communication signal can comprise of a preamble, a data symbol, communication data, etc. A first portion of the radar clutter is analyzed to determine a radar signature of the first portion of the radar clutter. A second portion of the radar clutter can be extracted based on the radar signature of the first portion. Following extraction, any residual signal can be analyzed to retrieve preamble data, etc. The received signal can be based upon a linear frequency modulation (e.g., a chirp modulation) whereby the chirp frequency can be determined and the frequency of transmission of the communication signal can be based accordingly thereon. The duration and/or bandwidth of the communication signal can be a portion of the duration and/or the bandwidth of the radar clutter.

First claim

What is claimed is:

1. A method, comprising:
receiving a signal at a receiver, the signal comprises:
a communication signal transmitted by a band-limited radio frequency (RF) transmitter; and
radar clutter, the radar clutter based upon a radar signal transmitted by a radar transmitter, wherein a first portion of the signal comprises a first portion of the radar clutter and a second portion of the signal comprises a second portion of the radar clutter and the communication signal, wherein the communication signal is band-limited by the band-limited RF transmitter according to at least one parameter associated with the radar clutter; and

extracting the communication signal from the signal, wherein extracting the communication signal comprises,
identifying the first portion of the radar clutter;
identifying the second portion of the radar clutter based upon the first portion of the radar clutter; and
identifying the communication signal in the signal based upon the identifying of the first portion of the radar clutter and the second portion of the radar clutter.

2. The method of claim 1 , wherein extracting the communication signal from the signal further comprises:
converting the first portion of the radar clutter to a rectangular array forming a first subaperture; and
converting the communication signal and the second portion of the radar clutter to a rectangular array forming a second subaperture, wherein the first subaperture and the second subaperture having the same area.

3. The method of claim 2 , wherein extracting the communication signal from the signal further comprises:
determining a radar signature of the first subaperture.

4. The method of claim 3 , wherein extracting the communication signal from the signal further comprises:
filtering the second subaperture with the radar signature of the first subaperture leaving a signal residue, wherein the signal residue is the communication signal.

5. The method of claim 1 , wherein the communication signal comprises at least one of a preamble, a data symbol, or communication data.

6. The method of claim 1 , wherein the communication signal has a shorter duration than the duration of the radar clutter.

7. The method of claim 1 , wherein a bandwidth of the communication signal is less than a bandwidth of the radar clutter.

8. The method of claim 1 , wherein the radar clutter being based at least in part on linear frequency modulation.

9. A system comprising:
a signal detection system configured to:
receive a signal comprising a combination of a communication signal and radar clutter, the communication signal transmitted by a band-limited radio frequency (RF) transmitter, the radar signal transmitted by a radar transmitter, wherein the band-limited RF transmitter band-limits the communication signal in accordance with a frequency of the radar signal, and further wherein a first portion of the received signal comprises a first portion of the radar clutter, and a second portion of the received signal comprises a second portion of the radar clutter and the communication signal;
identify the first portion of the radar clutter in the received signal;
identify the second portion of the radar clutter in the received signal based upon the first portion of the radar clutter; and
extract the communication signal from the received signal in response to the first portion and the second portion of the radar clutter being identified in the received signal.

10. The system of claim 9 , wherein the signal detection system is further configured to:
convert the received signal from a polar format to a rectangular grid having an X dimension and a Y dimension.

11. The system of claim 10 , wherein the signal detection system is further configured to:
separate the rectangular grid into two equally sized regions, a first region being a first subaperture comprising the first portion of the radar clutter and a second region being a second subaperture comprising the second portion of the radar clutter and the communication signal.

12. The system of claim 11 , wherein the signal detection system is further configured to:
determine a radar signature of the first portion of the radar clutter.

13. The system of claim 12 , wherein the signal detection system is further configured to:
extract the radar signature from the second subaperture, wherein the residue signal comprising the communication signal.

14. The system of claim 9 , wherein a bandwidth of the communication signal is configured in accordance with at least one parameter associated with the radar clutter.

15. The system of claim 9 , wherein the communication signal has a duration one half the duration of the radar clutter.

16. The system of claim 9 , wherein the communication signal comprises at least one of a preamble, a data symbol, or communication data.

17. The system of claim 9 , wherein the radar clutter being based at least in part on a chirp modulation of the radar signal.

18. A radar system comprising a memory that includes instructions that, when executed by a processor of the radar system, cause the processor to perform acts comprising:
receiving a signal, the signal comprising;
radar clutter that is based upon a radar signal transmitted by a radar transmitter, and
a communication signal transmitted by a band-limited radio frequency (RF) transmitter, wherein the band-limited RF transmitter band-limits the communication signal as a function of at least one parameter of the radar clutter;

generating a first subaperture comprising a first portion of the radar clutter;
generating a second subaperture comprising the communication signal and a second portion of the radar clutter, wherein the first subaperture has a same area as the second subaperture;
determining a signature of the first portion of the radar clutter;
filtering the second subaperture with the signature of the first portion to facilitate removal of the second portion of the radar clutter from the second subaperture; and
acquiring the communication signal in the second subaperture based upon removing the second portion of the radar clutter from the second subaperture.

19. The radar system of claim 18 , wherein the communication signal comprising at least one of a preamble, a data symbol, or communication data.

20. The radar system of claim 18 , wherein the communication signal has half of the duration of the radar signal.

Assignees

• Sandia Corp

Inventors

• Ormesher Richard C
• Naething Richard M

Classifications

• G01S13/348

  using square or rectangular modulation, e.g. diplex radar for ranging over short distances · CPC title

• G01S7/414 Primary

  Discriminating targets with respect to background clutter · CPC title

• G01S7/354

  Extracting wanted echo-signals (Doppler systems G01S13/50) · CPC title

• G01S13/90

  using synthetic aperture techniques {, e.g. synthetic aperture radar [SAR] techniques} · CPC title

• G01S13/9027

  Pattern recognition for feature extraction · CPC title