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An Analysis of ISAR Image Distortion Based on the Phase Modulation Effect

  • S. K. WongEmail author
  • E. Riseborough
  • G. Duff
Open Access
Research Article
Part of the following topical collections:
  1. Inverse Synthetic Aperture Radar

Abstract

Distortion in the ISAR image of a target is a result of nonuniform rotational motion of the target during the imaging period. In many of the measured ISAR images from moving targets, such as those from in-flight aircraft, the distortion can be quite severe. Often, the image integration time is only a few seconds in duration and the target's rotational displacement is only a few degrees. The conventional quadratic phase distortion effect is not adequate in explaining the severe blurring in many of these observations. A numerical model based on a time-varying target rotation rate has been developed to quantify the distortion in the ISAR image. It has successfully modelled the severe distortion observed; the model's simulated results are validated by experimental data. Results from the analysis indicate that the severe distortion is attributed to the phase modulation effect where a time-varying Doppler frequency provides the smearing mechanism. For target identification applications, an efficient method on refocusing distorted ISAR images based on time-frequency analysis has also been developed based on the insights obtained from the results of the numerical modelling and experimental investigation conducted in this study.

Keywords

Rotation Rate Rotational Motion Doppler Frequency Target Identification Image Distortion 

References

  1. 1.
    Sparr T, Hamran S-E, Korsbakken E: Estimation and correction of complex target motion effects ininverse synthetic aperture imaging of aircraft. Proceedings of IEEE International Radar Conference (RADAR '00), May 2000, Alexandria, Va, USA 457–462.Google Scholar
  2. 2.
    Chen VC, Miceli WJ: Simulation of ISAR imaging of moving targets. IEE Proceedings - Radar, Sonar and Navigation 2001, 148(3):160–166. 10.1049/ip-rsn:20010384CrossRefGoogle Scholar
  3. 3.
    Wang Y, Ling H, Chen VC: ISAR motion compensation via adaptive joint time-frequency technique. IEEE Transactions on Aerospace and Electronic Systems 1998, 34(2):670–677. 10.1109/7.670350CrossRefGoogle Scholar
  4. 4.
    Wehner DR: High-Resolution Radar. 2nd edition. Artech House, Boston, Mass, USA; 1995.Google Scholar
  5. 5.
    Chen VC, Miceli WJ: Time-varying spectral analysis for radar imaging of manoeuvring targets. IEE Proceedings - Radar, Sonar and Navigation 1998, 145(5):262–268. 10.1049/ip-rsn:19982220CrossRefGoogle Scholar
  6. 6.
    Chen VC, Ling H: Time-Frequency Transform for Radar Imagery and Signal Analysis. Artech House, Boston, Mass, USA; 2002.Google Scholar
  7. 7.
    Rihaczek AW, Hershkowitz SJ: Identification of targets from ISAR images. NATO Symposium on Target Identification and Recognition Using RF Systems, October 2004, Oslo, NorwayGoogle Scholar
  8. 8.
    Sparr T, Krane B: When are time-frequency methods useful for radar signature analysis. NATO Symposium on Target Identification and Recognition Using RF Systems, October 2004, Oslo, NorwayGoogle Scholar
  9. 9.
    Wong SK, Duff G, Riseborough E: Distortion in the inverse synthetic aperture radar (ISAR) images of a target with time-varying perturbed motion. IEE Proceedings - Radar, Sonar and Navigation 2003, 150(4):221–227. 10.1049/ip-rsn:20030638CrossRefGoogle Scholar
  10. 10.
    Wong SK, Duff G, Riseborough E: Analysis of distortion in the high range resolution profile from aperturbed target. IEE Proceedings - Radar, Sonar and Navigation 2001, 148(6):353–362. 10.1049/ip-rsn:20010716CrossRefGoogle Scholar
  11. 11.
    Cohen L: Time-frequency distributions—a review. Proceedings of the IEEE 1989, 77(7):941–980. 10.1109/5.30749CrossRefGoogle Scholar
  12. 12.
    Auger F, Flandrin P, Goncalves P, Lemoine O: Time-Frequency Toolbox for Use in MATLAB. Tutorial, July 15, 1997, https://doi.org/www.nongnu.org/tftb/Google Scholar
  13. 13.
    Wong SK, Riseborough E, Duff G: Application of phase modulation to ISAR image processing and counter-measures against radar imaging. Combat Identification Systems Conference, May 2005, Portsmouth, Va, USA Session 5, Paper 6Google Scholar

Copyright information

© Wong et al. 2006

Authors and Affiliations

  1. 1.Defence R&D Canada - OttawaOttawaCanada

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