Application of adaptive pulse compression (APC) in cluttered radar cross-section (RCS) measurements

Patent metadata

Field	Value
Publication number	US-12130376-B2
Application number	US-202318694705-A
Country	US
Kind code	B2
Filing date	Oct 13, 2023
Priority date	Oct 14, 2022
Publication date	Oct 29, 2024
Grant date	Oct 29, 2024

Abstract

A method comprising: obtaining I/Q data associated with a received radar signal; performing background subtraction on the I/Q data to obtain a subtracted signal; applying an algorithm to the subtracted signal to obtain a filtered signal, wherein the algorithm is based on a MSE filter; performing time-gating on the filtered signal to obtain a time-gated signal; applying a FFT to convert the time-gated signal to a frequency-domain signal; and applying a calibration set to the frequency-domain signal to extract an RCS of an OUT; and a system for conducting the method.

First claim

What is claimed is:

1. A method comprising:
obtaining in-phase/quadrature (I/Q) data associated with a received radar signal;
performing a background subtraction on the I/Q data to obtain a subtracted signal;
applying an algorithm to the subtracted signal to obtain a filtered signal, wherein the algorithm is based on a mean square error (MSE) filter;
performing a time-gating process on the filtered signal to obtain a time-gated signal;
applying a fast Fourier transform (FFT) to convert the time-gated signal to a frequency-domain signal;
applying a calibration set to the frequency-domain signal to extract a radar cross-section (RCS) of an object under test (OUT);
delivering the RCS to a user; and
manufacturing or modifying an object based on the RCS.

2. The method of claim 1 , wherein the background subtraction reduces or eliminates returns from scatterers other than the OUT.

3. The method of claim 1 , wherein applying the algorithm comprises applying the algorithm until a noise level limits a range profile estimation accuracy.

4. The method of claim 1 , further comprising further obtaining the I/Q data using a stepped-frequency continuous-wave (SFCW) radar, an SFCW waveform, an orthogonal frequency-division multiplexing (OFDM) radar, or an OFDM waveform.

5. The method of claim 4 , wherein obtaining the I/Q data using the SFCW radar comprises obtaining the I/Q data using a vector network analyzer (VNA) operating as the SFCW radar.

6. The method of claim 1 , wherein the MSE filter is a reiterative minimum mean square error (RMMSE) filter or is range dependent, or wherein the MSE filter comprises a cost function that preserves a complex magnitude of a main lobe associated with the OUT.

7. The method of claim 1 , wherein the algorithm uses adaptive pulse compression (APC).

8. The method of claim 1 , wherein applying the MSE filter comprises:
obtaining an initial range profile estimate with an inverse fast Fourier transform (IFFT);
estimating a noise variance;
estimating a power ρ(l);
computing a filter w(l);
estimating a range profile {circumflex over (x)}(l); and
reiterating estimating the power ρ(l), computing the filter w(l), and estimating the range profile {circumflex over (x)}(l) for P iterations.

9. The method of claim 1 , wherein the method is independent of a matched filter.

10. The method of claim 1 , wherein performing the time-gating process comprises:
converting the filtered signal to a time-domain signal using an inverse fast Fourier transform (IFFT); and
applying a window to the time-domain signal to obtain the time-gate signal,
wherein the window filters a range profile to include range bins associated with the OUT and suppress remaining range bins.

11. The method of claim 1 , wherein applying the calibration set comprises subtracting the calibration set from the frequency-domain signal.

12. The method of claim 1 , further comprising displaying the RCS.

13. A method comprising:
transmitting a transmitted signal;
obtaining in-phase/quadrature (I/Q) data associated with a received radar signal;
performing a background subtraction on the I/Q data to obtain a subtracted signal;
applying an algorithm to the subtracted signal to obtain a filtered signal, wherein the algorithm is based on a mean square error (MSE) filter;
performing a time-gating process on the filtered signal to obtain a time-gated signal;
applying a fast Fourier transform (FFT) to convert the time-gated signal to a frequency-domain signal;
applying a calibration set to the frequency-domain signal to extract a radar cross-section (RCS) of an object under test (OUT); and
delivering the RCS to a user.

14. The method of claim 13 , further comprising receiving the received radar signal in response to the transmitted signal.

15. A system comprising:
a memory configured to store instructions;
one or more processors coupled to the memory and configured to execute the instructions to cause the system to:
obtain in-phase/quadrature (I/Q) data associated with a received radar signal;
perform a background subtraction on the I/Q data to obtain a subtracted signal;
apply an algorithm to the subtracted signal to obtain a filtered signal, wherein the algorithm is based on a mean square error (MSE) filter;
perform a time-gating process on the filtered signal to obtain a time-gated signal;
apply a fast Fourier transform (FFT) to convert the time-gated signal to a frequency-domain signal; and
apply a calibration set to the frequency-domain signal to extract a radar cross-section (RCS) of an object under test (OUT), wherein the RCS is delivered to a user; and

a transceiver configured to:
transmit a transmitted signal; and
receive the received radar signal in response to the transmitted signal.

16. The system of claim 15 , further comprising a display configured to display the RCS.

17. The system of claim 15 , wherein the background subtraction reduces or eliminates returns from scatterers other than the OUT.

18. The system of claim 15 , wherein the instructions, when executed by the one or more processors, further cause the system to further apply the algorithm until a noise level limits a range profile estimation accuracy.

19. A computer program product comprising instructions that are stored on a non-transitory computer-readable medium and that, when executed by one or more processors, cause a system to:
transmit a transmitted signal;
obtain in-phase/quadrature (I/Q) data associated with a received radar signal;
perform a background subtraction on the I/Q data to obtain a subtracted signal;
apply an algorithm to the subtracted signal to obtain a filtered signal, wherein the algorithm is based on a mean square error (MSE) filter;
perform a time-gating process on the filtered signal to obtain a time-gated signal;
apply a fast Fourier transform (FFT) to convert the time-gated signal to a frequency-domain signal; and
apply a calibration set to the frequency-domain signal to extract a radar cross-section (RCS) of an object under test (OUT), wherein the RCS is delivered to a user.

20. The computer program product of claim 19 , wherein the algorithm uses adaptive pulse compression (APC).

Assignees

• Univ Oklahoma

Inventors

• Mcdaniel Jay W
• Metcalf Justin G
• Jarvis Rachel E

Classifications

• G01S13/282

  using a frequency modulated carrier wave (G01S13/286 takes precedence) · CPC title

• G01S7/411

  Identification of targets based on measurements of radar reflectivity (G01S7/415 takes precedence) · CPC title

• G01S7/32

  Shaping echo pulse signals; Deriving non-pulse signals from echo pulse signals · CPC title

• G01S7/414

  Discriminating targets with respect to background clutter · CPC title

• G01S13/288

  phase modulated · CPC title