Through-wall imaging (TWI) is one of the useful applications nowadays in microwave tomography field. Reconstructing image of an object becomes more challenging when it is obscured by walls. In practice, the inclusions of noise worsen the reconstruction results. In this paper, Forward-Backward Time-Stepping (FBTS) in time inversion technique is utilized and integrated with Wall Direct Subtraction (WDS) method to reconstruct unknown object behind walls. The investigation includes two types of walls that are homogeneous and heterogeneous. The object is surrounded by closed walls. With noise added in the setup, Singular Value Decomposition (SVD) and Savitzky-Golay (SG) filtering method are used to eliminate the noise and enhance the reconstructed image of an object. The results show that WDS integrated with FBTS has successfully mitigating wall clutter from both homogeneous and heterogeneous walls, and also improves image reconstruction of a hidden object. Further, by using the proposed noise reduction method, lower MSE values can be achieved.
1. Yoon, Y. and M. G. Amin, "Spatial filtering for wall-clutter mitigation in through-the-wall radar imaging," IEEE Trans. Geosci. Remote Sens., Vol. 47, No. 9, 3192-3208, 2009. doi:10.1109/TGRS.2009.2019728
2. Baranoski, E. J. and N. F. Drive, "Through wall imaging: Historical perspective and future directions," J. Franklin Inst., Vol. 345, No. 6, 556-569, 2008. doi:10.1016/j.jfranklin.2008.01.005
3. Salvador, S. M., E. C. Fear, M. Okoniewski, and J. R. Matyas, "Exploring joint tissues with microwave imaging," IEEE Trans. Microw. Theory Tech., Vol. 58, No. 8, 2307-2313, 2010. doi:10.1109/TMTT.2010.2052662
4. Wentworth, S. M., Fundamentals of Electromagnetics with Engineering Applications, John Wiley & Sons, Inc., USA, 2005.
5. Syahrim, N. and N. Anwar, "Multiple line cracks in concrete material," Int. J. Hum. Technol. Interact., Vol. 2, October 2018.
6. Hong Ping, K. A., T. Moriyama, T. Takenaka, and T. Tanaka, "Reconstruction of breast composition in a free space utilizing 2-D forward-backward time-stepping for breast cancer detection," 4th lET Intematioal Conf. Adv. Medical, Signal Inf. Process. 2008 (MEDSIP 2008), 1-4, 2008.
7. Hong, K. A., T. Moriyama, T. Takenaka, and T. Tanaka, "Two-dimensional forward-backward time-stepping approach for tumor detection in dispersive breast tissues," Microw. Symp. (MMS), 2009 Mediterr., 2009.
8. Kaushal, S. and D. Singh, "Sensitivity analysis of microwave UWB radar for TWI system," Int. J. Appl. Eng. Res., Vol. 12, No. 19, 8665-8675, 2017.
9. Solimene, R., F. Soldovieri, G. Prisco, and R. Pierri, "Three-dimensional through-wall imaging under ambiguous wall parameters," IEEE Trans. Geosci. Remote Sens., Vol. 47, No. 5, 1310-1317, 2009.
10. Gaikwad, A. N., D. Singh, and M. J. Nigam, "Application of clutter reduction techniques for detection of metallic and low dielectric target behind the brick wall by stepped frequency continuous wave radar in ultra-wideband range," IET Radar, Sonar Navig., Vol. 5, 416-425, 2011.
11. Soldovieri, F. and R. Solimene, "Through-wall imaging via a linear inverse scattering algorithm," IEEE Geosci. Remote Sens. Lett., Vol. 4, No. 4, 513-517, 2007.
12. Dehmollaian, M. and K. Sarabandi, "Refocusing through building walls using synthetic aperture radar," IEEE Trans. Geosci. Remote Sens., Vol. 46, No. 6, 1589-1599, 2008.
13. Ahmad, F., S. Member, M. G. Amin, and G. Mandapati, "Autofocusing of through-the-wall radar imagery under unknown wall characteristics," IEEE Trans. Signal Process., Vol. 16, No. 7, 1785-1795, 2007.
14. Paknys, R., "Reflection and transmission by reinforced concrete — Numerical and asymptotic analysis," IEEE Trans. Antennas Propag., Vol. 51, No. 10, 2852-2861, 2003.
15. Liang, F., et al., "Through the wall imaging of human vital signs based on UWB MIMO bioradar," Progress In Electromagnetics Research C, Vol. 87, 119-133, 2018.
16. Jia, S., L. Kong, and Y. Jia, "A new approach for target localization of through-the-wall radar with unknown walls," IEEE Natl. Radar Conf. — Proc., No. 3, 7-10, 2009.
17. Gennarelli, G. and F. Soldovieri, "Radar imaging through cinderblock walls: Achievable performance by a model-corrected linear inverse scattering approach," IEEE Trans. Geosci. Remote Sens., Vol. 52, No. 10, 6738-6749, 2014.
18. Burkholder, R. J., R. J. Marhefka, and J. L. Volakis, "Radar imaging through cinder block walls and other periodic structures," 2008 IEEE Antennas Propag. Soc. Int. Symp., 3-6, 2008.
19. Turk, A. S., K. A. Hocaoglu, and A. A. Vertiy, Subsurface Sensing, Volume 197 of Wiley Series in Microwave and Optical Engineering, John Wiley & Sons, 2011.
20. Yemelyanov, K. M., N. Engheta, A. Hoorfar, and J. A. Mcvay, "Adaptive polarization contrast techniques for through-wall microwave imaging applications," IEEE Trans. Geosci. Remote Sens., Vol. 47, No. 5, 1362-1374, 2009.
21. Pierri, R., A. Liseno, R. Solimene, and F. Soldovieri, "Beyond physical optics SVD shape reconstruction of metallic cylinders," IEEE Trans. Antennas Propag., Vol. 54, No. 2, 655-665, 2006.
22. Zhong, W. and C. Tong, "A novel near field imaging approach for through-wall imaging," Cross Strait Quad-Regional Radio Sci. Wirel. Technol. Conf., 164-167, 2011.
23. Miao, Z. and P. Kosmas, "Compact of information loss on reconstruction quality in microwave tomography for medical imaging," Diagnostics, Vol. 8, No. 52, 1-15, 2018.
24. Jin, T., B. Chen, and Z. Zhou, "Image-domain estimation of wall parameters for autofocusing of through-the-wall SAR imagery," IEEE Trans. Geosci. Remote Sens., Vol. 51, No. 3, 1836-1843, 2013.
25. Liseno, A., F. Soldovieri, and R. Pierri, "Improving a shape reconstruction algorithm with thresholds and multi-view data," AEU — Int. J. Electron. Commun., Vol. 58, No. 2, 118-124, 2004.
26. Riaz, M. M. and A. Ghafoor, "Wavelet transform and singular value decomposition based clutter reduction for through wall imaging," Radar Conf. IET Int., 2013.
27. Tivive, F. H. C., M. G. Amin, and A. Bouzerdoum, "Wall clutter mitigation based on eigen-analysis in through-the-wall radar imaging," 17th DSP 2011 Int. Conf. Digit. Signal Process. Proc., 1-8, 2011.
28. Gorji, A. B. and B. Zakeri, "An improved time-reversal-based target localization for through-wall microwave imaging," J. Electr. Comput. Eng. Innov. JECEI Regul. Pap. 89 J. Elec. Comput. Eng. Innov., Vol. 1, No. 2, 89-97, 2013.
29. Zheng, W., Z. Zhao, and Z. Nie, "Application of TRM in the UWB through wall radar," Progress In Electromagnetics Research, Vol. 87, 279-296, 2008.
30. Cresp, A., I. Aliferis, M. Yedlin, C. Pichot, and J. Dauvignac, "Investigation of time-reversal processing for surface-penetrating radar detection in a multiple-target configuration," Proc. 5th Eur. Radar Conf. Amsterdam, Netherlands, 144-247, 2008.
31. Wu, H. and J. Barba, "Minimum entropy restoration of star field images," IEEE Trans. Syst. Man, Cybern. B Cybern., Vol. 28, No. 2, 227-231, 1998.
32. Solimene, R., A. Cuccaro, R. Pierri, and I. Industriale, "A clutter rejection based on entropy in TWI," 7th Eur. Conf. Antennas Propag., 2175-2178, 2013.
33. Li, L., W. Zhang, and F. Li, "A novel autofocusing approach for real-time through-wall imaging under unknown wall characteristics," IEEE Trans. Geosci. Remote Sens., Vol. 48, No. 1, 423-431, 2010.
34. Muqaibel, A. H., N. M. Iya, and U. M. Johar, "Wall compensation for ultra wideband applications," Radioengineering, Vol. 21, No. 2, 640-646, 2012.
35. Elizabeth, M. A. P., et al., "2-D reconstruction of breast image using forward-backward time-stepping method for breast tumour detection," IEEE Asia-Pacific Conf. Appl. Electromagn. (APACE 2012), No. Apace, 70-73, 2012.
36. Nawawi, J., S. Sahrani, K. Anak, and H. Ping, "Automated scaling region of interest with iterative edge preserving in forward-backward time-stepping," Progress In Electromagnetics Research, Vol. 67, 177-188, 2018.
37. Joseph, E. J., et al., "Integration of image segmentation method in inverse scattering for brain tumour detection," Progress In Electromagnetics Research, Vol. 61, 111-122, 2017.
38. Ping, K. H., S. W. Ng, G. Yong, and N. Rajaee, "Elliptic filter and iterative inversion method for buried object detection applications," Applied Mechanics and Materials, Vol. 833, 164-169, 2016.
39. Elizabeth, M. A. P., K. A. Hong Ping, N. B. Rajaee, and T. Moriyama, "Chebyshev filter applied to an inversion technique for breast tumour detection," Int. J. Res. Eng. Technol., Vol. 4, No. 5, 1-9, 2015.
40. Yong, G., K. A. H. Ping, S. Sahrani, M. H. Marhaban, M. I. Sariphn, T. Moriyama, and T. Takenaka, "Profile reconstruction utilizing forward-backward time-stepping with the integration of automated edge-preserving regularization technique for object detection applications," Progress In Electromagnetics Research M, Vol. 54, 125-135, 2017.
41. Jamali, N. H., K. Anak, H. Ping, and S. Sahrani, "Image reconstruction based on combination of inverse scattering technique and total variation regularization method," Indonesian Journal of Electrical Engineering and Computer Science, Vol. 5, No. 3, 569-576, 2017.
42. Xu, K., Y. Zhong, X. Chen, and D. Lesselier, "A fast integral equation based method for solving electromagnetic inverse scattering problems with inhomogeneous background," IEEE Trans. Antennas Propag., Vol. 66, No. 8, 4228-4239, 2018.
43. Zehtabian, A. and H. Hassanpour, "A non-destructive approach for noise reduction in time domain," World Appl. Sci. J., Vol. 6, No. 1, 53-63, 2009.
44. Gorji, A. B. and B. Zakeri, "Time-reversal through-wall microwave imaging in rich scattering environment based on target initial reflection method time-reversal through-wall microwave imaging in rich scattering," Appl. Comput. Electromagn. Soc. J., Vol. 30, 625-637, June 2015.
45. Tivive, F. H. C., A. Bouzerdoum, and M. G. Amin, "An SVD-based approach for mitigating wall reflections in through-the-wall radar imaging," IEEE Natl. Radar Conf. — Proc., No. 2, 519-524, 2011.
46. Gander, W. and V. von Matt, "Smoothing filters," Solving Problems in Scientific Computing Using Maple and MATLAB, 135-154, Springer, 1997.
47. Schafer, R. W., "What is a Savitzky-Golay filter," IEEE Signal Processing Magazine, 111-117, 2011.
48. Selesnick, I., J. Rizzo, J. Rucker, and T. Hudson, "A nonlinear generalization of the Savitzky-Golay filter and the quantitative analysis of saccades," J. Vis., Vol. 9, 1-15, 2017.
49. Liu, Y., B. Dang, Y. Li, H. Lin, and H. Ma, "Applications of Savitzky-Golay filter for seismic random noise reduction," Acta Geophys., Vol. 64, No. 1, 101-124, 2016.