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

摘要/Abstract

摘要：

为了解决传统后向投影(back-projection, BP)算法中, 成像清晰度受硬件限制、复杂运动难以算法修正的问题, 提出了一种基于信号分析, 采用切比雪夫拟合的聚焦处理方法。考虑到非线性运动下的BP成像带有大距离变化产生的算法处理误差, 导航器件补偿参数难以修正, 该算法以信号回波数据为基础, 采用改进的自动聚焦算法来修正距离误差带来的成像干扰, 可在雷达系统内高效实现。分析了BP成像算法的误差和自聚焦算法, 将原始BP成像图像与经自动聚焦处理的图像进行比较, 检验算法的性能。仿真结果表明, 抛物线轨迹下的改进BP自动聚焦算法处理后的图像效果优于未处理图像。

关键词: 后向投影算法, 自聚焦算法, 抛物轨迹, 切比雪夫拟合

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

中图分类号:

TN957.52

李彦君, 刘佳, 徐秋锋. 基于切比雪夫拟合的BP自聚焦算法[J]. 系统工程与电子技术, 2022, 44(10): 3020-3028.

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

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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