THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. 2017 Jun.; 28(6), 459469. http://dx.doi.org/10.5515/kjkiees.2017.28.6.459 ISSN 1226-3133 (Print)ISSN 2288-226X (Online) (W ) FMCW SAR Forward-Looking GMTI and Estimation of Position and Velocity Based on Millimeter-Wave(W-Band) FMCW SAR 이혁중 전주환 송성찬 Hyukjung LeeJoohwan ChunSungchan Song* 요약. Frequency Modulated Continuous Wave(FMCW) (synthetic aperture radar: SAR). (maximum likelihood estimation: MLE) (phase history)(image). Abstract An air-to-ground guidance missile aimed to hit a main battle tank(mbt) should detect a ground moving target and estimate the target position to guide. In this paper, we detect a front ground moving target by using FMCW(Frequency Modulated Continuous Wave) and estimate the position by forward-looking SAR(Synthetic Aperture Radar) via scanning certain front ground section by steering a beam with narrow beamwidth left to right mechanically. Also, by MLE(Maximum Likelihood Estimation), degree of how fast the target approach or recede from the radar can be figured out from the estimated radial velocity of the moving target. Subsequently, we generate a radar image via corrected matched filter from phase history including the radial velocity. Key words: FMCW, SAR, GMTI, MLE, Phase History, Guidance Missile. 서론, FMCW(Frequency Modulated Continuous Wave) brimstone [1]. Brimstone 1 (beam),. (Department of Electronic Engineering, KAIST) *(Hanwha Systems) Manuscript receive April 12, 2016; Revised June 21, 2016; Accepted May 23, 2017 (ID No. 20160412-039) Corresponding Author: Hyukjung Lee (e-mail: wooa@kaist.ac.kr) c Copyright The Korean Institute of Electromagnetic Engineering and Science. All Rights Reserved. 459
THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 28, no. 6, Jun. 2017. [9]. FMCW SAR,.. 모의실험원시데이터생성 그림 1. Fig. 1. Forward-looking SAR geometry. 1. 1 km, θ s (footprint),. (SAR: Synthetic Aperture Radar),, FMCW FMCW SAR [2]~[6].. [1],[7],[8] FMCW [1], (phase history). (range bin). (peak) 1,,. h, x, y, z (line of sight) cos cos sin sin cos. 2,,.. 2 (). (a) (b) 그림 2. (a) (b) Fig. 2. Footprint for constant beam width(a) and relation between line of sight of radar and footprint length(b). 460
(W ) FMCW SAR (a) 그림 3. Fig. 3. Combined ellipse in rotated axises. 3,.,,. (1) 4,. tan (2) tan tan, (3) tan tan. (4), cos sin cos. (1)., (1) (b) (c) 그림 4. (a), Fig. 4. Major and minor axis of ellipse from 1 st, 2 nd plane in upper figure. sin cos cos cos sin sin sin cos cos cos (5).. FMCW 신호분석 FMCW 5.,, 1 ms, 300 MHz, 94 GHz [1]. (pulse repetition interval) 1 ms 5. (fast-time) (slow-time).,,. 461
THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 28, no. 6, Jun. 2017... (9) 그림 5. FMCW Fig. 5. FMCW pulse representation.. 3-1 빠른시간 (Fast-Time) 분석 FMCW. exp (6),, S(500 us). 1, τ. exp (7). FMCW (conjugate).. exp (8), (Taylor series). (8) 1.. exp exp exp exp (10),,. t 2 f b -f D.. (Fourier transform) 0 exp. 3-2 느린시간 (Slow-Time) 분석,. [10],[11]. FMCW. 462
(W ) FMCW SAR exp exp (11) t start (sampling) m ax m ax. (slow-time).,. (12) (13) (14). R(0), R (0),., (12)(14) (11),.. 거리빈천이현상및위상오류보정,., (15).. FMCW,.. (16),,,,, [12].., 1,. cos cos (17),.. k. (18) cos cos.. DFT(Discrete Fourier Transform). 6 m, DFT (index) k. 463
THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 28, no. 6, Jun. 2017. 그림 6. DFT(Discrete Fourier Transform)() DTFT () m DFT k Fig. 6. Comparison of DFT and DTFT respect to peak position. exp, N. m DFT [9]. Re (19) DFT. exp. (20). 움직이는지상표적탐지 FMCW. ( ) (10)..,. km/h -8.7 khz 2 khz 4.. 1, 1 2. (11).... exp (21), (measurement),,. nuisance. (21),. (22) 464
(W ) FMCW SAR exp exp (23). (24) (25). (26) 7 SAR. FMCW FFT,.. FMCW, MLE. SAR.,.. 모의실험결과 1 [1]. [m] 1, -9 9 200 ms 16 ms 8. 8 표 1. Table 1. Simulation parameters. Parameters Height of the vehicle Values 50 m Steering angle θ s 3.56 Elevation beamwidth θ b 1.4 Azimuth beamwidth 1.4 Velocity of the vehicle v Sampling frequency f s PRI Bandwidth Range resolution 450 m/s 10 MHz 1 ms 300 MHz 0.5304 m 그림 7. Fig. 7. Block diagram of overall process. 그림 8. 200 ms Fig. 8. Point target and footprints during 200 ms. 465
THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 28, no. 6, Jun. 2017. 800 m 330 300 m,. 9 FMCW FFT(Fast Fourier Transform),.,.. 8 13 ms, 13. 1767 889.00 m, =888.98 m. 10 9. 9.,., x, y (878.06, -130.04).. 11. (898, -130) (882, -107) (878.06, -130.04), (882.26, -107.05),. (a) (b) 그림 9. Fig. 9. Results of range compression. 그림 10. (a) x, y (b) Fig. 10. Azimuth compression result(a) and image on x, y axis(b). 466
(W ) FMCW SAR (903.60, 4.46), (904.87, 25.73) (903.5, 4), (905, 25.5),.. FMCW. (878, -130), (882, -107) (878, -130) -50 km/h 12.,. 4. 2 8,. 13. -50 km/h, -49.75 km/h. (a) (a) (b) (b) 그림 11. (a) (b) x, y Fig. 11. Image of two targets on left side(a) and on center (b) on x, y axis. (c) 그림 12. (a), (b) (c) Fig. 12. Range compression for up sweep(a) and down sweep (b) and result of subtraction(c). 467
THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 28, no. 6, Jun. 2017. 그림 13. Fig. 13. Result of maximum likelihood estimation..,. 11.. 결론,. FMCW,.. (integration time). References [1] Brooker, Graham, Alan T. Brooker, Introduction to Sensors for Ranging and Imaging, SciTech Pub. Incorporated, 2009. [2] Meta, Adriano, Signal Processing of FMCW Synthetic Aperture Radar Data, TU Delft, Delft University of Technology, 2006. [3] R. Wang, O. Loffeld, H. Nies, S. Knedlik, M. Hagelen, and H. Essen, "Focus FMCW SAR data using the wavenumber domain algorithm", IEEE Transactions on Geoscience and Remote Sensing, vol. 48, no. 4, pp. 2109-2118, 2010. [4] A. Ribalta, "Time-domain reconstruction algorithms for FMCW-SAR", IEEE Geoscience and Remote Sensing Letters, vol. 8, no. 3, pp. 396-400, 2011. [5] Z. H. Jiang, H. F. Kan, and J. W. Wan, "A chirp transform algorithm for processing squint mode FMCW SAR data", IEEE Geoscience and Remote Sensing Letters, vol. 4, no. 3, pp. 377-381, 2007. [6] Yue Liu, Yun Kai Deng, R. Wang, and O. Loffeld, "Bistatic FMCW SAR signal model and imaging approach", IEEE Transactions on Aerospace and Electronic Systems, vol. 49, no. 3, pp. 2017-2028, 2013. [7] P. Cheng, Q. Xin, J. Wan, and Z. Wang, "Efficient detection of ground moving targets in FMCW SAR by focusing", IEEE Transactions on Geoscience and Remote Sensing (IGARSS), vol. 53, no. 2, pp. 920-932, 2015. [8] A. Meta, P. Hoogeboom, "Signal processing algorithms for FMCW moving target indicator synthetic aperture radar", in Proc. IGARSS '05, vol. 1, pp. 316-319, 2005. [9] Eric Jacobsen, Peter Kootsookos, "Fast, accurate frequency estimators", IEEE Signal Processing Magazine, vol. 24, no. 3, pp. 123-125, 2007. [10] Ozdemir Caner, Inverse Synthetic Aperture Radar Imaging with MATLAB Algorithms, vol. 210, John Wiley & Sons, 2012. [11] Soumekh, Mehrdad. Synthetic Aperture Radar Signal Processing, New York: Wiley, 1999. [12] Beard, Gavin Spencer, Performance Factors for Airborne Short-Dwell Squinted Radar Sensors, Diss. UCL (University College London), 2011. 468
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