基于切比雪夫拟合的BP自聚焦算法

doi:10.12305/j.issn.1001-506X.2022.10.04

Abstract

Abstract:

In order to solve the problems of the back-projection (BP) algorithm, the imaging clarity is limited by hardware, and complex motion is difficult to correct algorithmically, a focus processing method based on signal analysis using Chebyshev fitting is proposed. Considering that BP imaging under non-linear motion has algorithm processing errors caused by large range changes, it is difficult to correct the compensation parameters of navigation devices. The algorithm is based on the signal echo data, the improved autofocus algorithm is used to correct the imaging interference caused by range error, which can be realized efficiently in radar system. The error of BP imaging algorithm and the autofocus algorithm are analyzed. The performance of the algorithm is verified by comparing the original BP image with the image processed by autofocus. The simulation results show that the improved BP autofocus algorithm under the parabolic trajectory has a better focusing effect than the unprocessed image.

Key words: back-projection (BP) algorithm, autofocus algorithm, parabolic trajectory, Chebyshev fitting

CLC Number:

TN957.52

Yanjun LI, Jia LIU, Qiufeng XU. BP autofocus algorithm based on Chebyshev fitting[J]. Systems Engineering and Electronics, 2022, 44(10): 3020-3028.

Figures/Tables 13

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References 31

1	EVERS A, JACKSON J A. A comparison of autofocus algorithms for backprojection synthetic aperture radar[C]//Proc. of the IEEE International Radar Conference, 2020: 821-826.
2	邢孟道, 林浩, 陈溅来, 等. 多平台合成孔径雷达成像算法综述[J]. 雷达学报, 2019, 8 (6): 732- 757.
	XING M D , LIN H , CHEN J L , et al. A review of imaging algorithms in multi-platform-borne synthetic aperture radar[J]. Journal of Radars, 2019, 8 (6): 732- 757.
3	KANTOR J M. Differentiable synthetic aperture radar image formation and generalized minimum entropy autofocus[C]//Proc. of the IEEE Radar Conference, 2021.
4	DING J, WU Y F, ZHANG H B. A fast BP algorithm for bistatic spotlight SAR based on spectrum compression[C]//Proc. of the IEEE 6th Asia-Pacific Conference on Synthetic Aperture Radar, 2019.
5	CUI G L, KONG L J, YANG J Y. A back-projection algorithm to stepped-frequency synthetic aperture through-the-wall radar imaging[C]//Proc. of the IEEE Asian and Pacific Conference on Synthetic Aperture Radar, 2007: 123-126.
6	SONG J W , PARK C G . INS/GPS integrated smoothing algorithm for synthetic aperture radar motion compensation using an extended Kalman filter with a position damping loop[J]. International Jour-nal of Aeronautical and Space Sciences, 2017, 18 (1): 118- 128. doi: 10.5139/IJASS.2017.18.1.118
7	ZHANG Z Y, PAPPAS O, ACHIM A. SAR image autofocusing using Wirtinger calculus and Cauchy regularization[C]//Proc. of the IEEE International Conference on Acoustics, Speech and Signal Processing, 2021: 1455-1459.
8	GARREN D A. Robustness of sar refraction autofocus to power-law errors[C]//Proc. of the IEEE International Radar Confe-rence, 2019.
9	LI Z , ZAN Y K . Performance analysis of autofocus algorithms for compensating ionospheric dispersion effect on spaceborne low-frequency SAR focusing[J]. IEEE Geoscience and Remote Sensing Letters, 2021, 18 (2): 331- 335. doi: 10.1109/LGRS.2020.2970720
10	LI Y , O'YOUNG S . Kalman filter disciplined phase gradient autofocus for stripmap SAR[J]. IEEE Trans.on Geoscience and Remote Sensing, 2020, 58 (9): 6298- 6308. doi: 10.1109/TGRS.2020.2976655
11	ZHANG T H, LI Y C, ZHANG T, et al. Expediting phase gradient autofocus algorithm for SAR imaging[C]//Proc. of the IEEE International Geoscience and Remote Sensing Symposium, 2020: 1145-1148.
12	SCHULZ T J . Optimal sharpness function for SAR autofocus[J]. IEEE Signal Processing Letters, 2006, 14 (1): 27- 30.
13	CALLOWAY T M, JAKOWATZ J C V, THOMPSON P A, et al. Comparison of synthetic-aperture radar autofocus techniques: phase gradient versus subaperture[C]//Proc. of the Advanced Signal Processing Algorithms, Architectures, and Implementations Ⅱ. International Society for Optics and Photonics, 1991, 1566: 353-364.
14	RAN L , LIU Z , ZHANG L , et al. Multiple local autofocus back-projection algorithm for space-variant phase-error correction in synthetic aperture radar[J]. IEEE Geoscience and Remote Sensing Letters, 2016, 13 (9): 1241- 1245. doi: 10.1109/LGRS.2016.2578719
15	CHEN L P , AN D X , HUANG X T . Extended autofocus backprojection algorithm for low-frequency SAR imaging[J]. IEEE Geoscience and Remote Sensing Letters, 2017, 14 (8): 1323- 1327. doi: 10.1109/LGRS.2017.2711005
16	CAI J J , MARTORELLA M , CHANG S Q , et al. Efficient nonparametric ISAR autofocus algorithm based on contrast maximization and Newton's method[J]. IEEE Sensors Journal, 2020, 21 (4): 4474- 4487.
17	TORGRIMSSON J , DAMMERT P , HELLSTEN H , et al. SAR processing without a motion measurement system[J]. IEEE Trans.on Geoscience and Remote Sensing, 2019, 57 (2): 1025- 1039. doi: 10.1109/TGRS.2018.2864243
18	WU J J , LI Y L , PU W , et al. An effective autofocus method for fast factorized back-projection[J]. IEEE Trans.on Geo-science and Remote Sensing, 2019, 57 (8): 6145- 6154. doi: 10.1109/TGRS.2019.2904608
19	SHI T Y, BAO Y, MAO X H, et al. Two-dimensional auto-focus approach for bistatic SAR polar format algorithm[C]//Proc. of the IEEE International Symposium on Antennas and Propagation, 2021: 231-232.
20	LI G F, ZHANG G, QIN H L, et al. A non-linearly moving ship autofocus method under hybrid coordinate system[C]//Proc. of the International Geoscience and Remote Sensing Symposium, 2020: 2471-2474.
21	LIU M, LI C S, SHI X H. A back-projection fast autofocus algorithm based on minimum entropy for SAR imaging[C]//Proc. of the IEEE 3rd International Asia-Pacific Conference on Synthetic Aperture Radar, 2011.
22	HU K B , ZHANG X L , HE S F , et al. A less-memory and high-efficiency autofocus back projection algorithm for SAR imaging[J]. IEEE Geoscience and Remote Sensing Letters, 2015, 12 (4): 890- 894. doi: 10.1109/LGRS.2014.2365612
23	SOMMER A , OSTERMANN J . Backprojection subimage autofocus of moving ships for synthetic aperture radar[J]. IEEE Trans.on Geoscience and Remote Sensing, 2019, 57 (11): 8383- 8393. doi: 10.1109/TGRS.2019.2920779
24	NOCEDAL J , WRIGHT S . Numerical optimization[M]. Berlin: Springer Science & Business Media, 2006.
25	史丽萍, 孙宝元, 于浩洋. 切比雪夫多项式回归分析方法在测量数据处理中的应用[J]. 黑龙江大学自然科学学报, 2003, 2, 78- 81.
	SHI L P , SUN B Y , YU H Y . Application of Chebyshev polynomial regression analysis method in measurement data processing[J]. Journal of Natural Science of Heilongjiang University, 2003, 2, 78- 81.
26	李庆阳, 王能超, 易大义. 数值分析[M]. 5版北京: 清华大学出版社, 2008.
	LI Q Y , WANG N C , YI D Y . Numerical analysis[M]. 5th ed Beijing: Tsinghua University Publishing House, 2008.
27	陶楚国. 一般四次函数的对称性及其性质[J]. 数学通讯, 2005, 4, 30- 32.
	TAO C G . Symmetry and properties of general quartic functions[J]. Bulletin of Mathematics, 2005, 4, 30- 32.
28	YIN Y W , LIU F L , WANG Z , et al. Synthetic aperture radar autofocus based on phaseless measurements[J]. Journal of Applied Remote Sensing, 2020, 14 (1): 014515.
29	LIU K H , WIESEL A , MUNSON D C . Synthetic aperture radar autofocus based on a bilinear model[J]. IEEE Trans.on Image Processing, 2012, 21 (5): 2735- 2746. doi: 10.1109/TIP.2012.2183881
30	ASH J N . An autofocus method for backprojection imagery in synthetic aperture radar[J]. IEEE Geoscience and Remote Sensing Letters, 2012, 9 (1): 104- 108. doi: 10.1109/LGRS.2011.2161456
31	LIAO Y, SHAO H Z, CHEN H, et al. A modefied PGA motion compensation method for circular trace scanning SAR[C]//Proc. of the IEEE International Conference on Radar, 2016.

拟合阶数	运行时间/s	拟合状态
1阶拟合	0.000 278	欠拟合
2阶拟合	0.000 301	欠拟合
3阶拟合	0.000 311	拟合
4阶拟合	0.000 324	拟合
9阶拟合	0.000 359	拟合
15阶拟合	0.000 452	过拟合
21阶拟合	0.001 409	过拟合

算法参数	数值
雷达频率/GHz	16
距离带宽/MHz	120
合成孔径时间/s	0.5
脉冲宽度/μs	50
脉冲重复频率/kHz	4
高度/m	7 264
中心斜距/m	18 285
斜视角/(°)	68
速度/(m/s)	0, 200, －42
加速度/(m/s²)	3.1, 2.4, －1.2

聚焦参数	PSLR	ISLR
理论图像	-11.4	-13.4
散焦图像	-7.65	-10.45
本文聚焦算法	-10.66	-16.06

聚焦参数	未处理图像	聚焦处理图像
IE	7.456 8	7.067 2
IAG	7.393 4	25.210 6
ISD	39.274 8	43.746 2
ISF	23.194 0	54.770 6

聚焦参数	PGA算法	本文聚焦算法
IE	7.389 3	7.067 2
IAG	10.490 8	25.210 6
ISD	45.005 0	43.746 2
ISF	29.789 7	54.770 6

BP autofocus algorithm based on Chebyshev fitting

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