Skip to main content

Advertisement

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

Article metrics

  • 755 Accesses

  • 4 Citations

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.

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.

  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:20010384

  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. 10.1109/7.670350

  4. 4.

    Wehner DR: High-Resolution Radar. 2nd edition. Artech House, Boston, Mass, USA; 1995.

  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:19982220

  6. 6.

    Chen VC, Ling H: Time-Frequency Transform for Radar Imagery and Signal Analysis. Artech House, Boston, Mass, USA; 2002.

  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, Norway

  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, Norway

  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:20030638

  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:20010716

  11. 11.

    Cohen L: Time-frequency distributions—a review. Proceedings of the IEEE 1989, 77(7):941–980. 10.1109/5.30749

  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/

  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 6

Download references

Author information

Correspondence to S. K. Wong.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Wong, S.K., Riseborough, E. & Duff, G. An Analysis of ISAR Image Distortion Based on the Phase Modulation Effect. EURASIP J. Adv. Signal Process. 2006, 083727 (2006) doi:10.1155/ASP/2006/83727

Download citation

Keywords

  • Rotation Rate
  • Rotational Motion
  • Doppler Frequency
  • Target Identification
  • Image Distortion