面目标回波处理算法对比及OCOG算法的改进分析
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摘要
针对传统海面回波处理算法以及频率校正算法无法有效应用于地面目标回波的问题,基于重心偏移法(OCOG)具有强鲁棒性的特点,着重对该算法性能进行研究,并对其重心公式的阶数m进行了讨论,仿真比较了OCOG法、质心估计法以及面积中心法在不同工况下的性能表现。仿真结果表明:OCOG法与面积中心法性能相近,但在入射角为25°到60°范围内OCOG更优;在入射角低于25°时,质心估计法误差较大,但在入射角大于25°时,质心估计法也具有其应用价值。基于OCOG法存在的偏差与抖动提出了改进方法,通过重心迭代使重心频率趋于收敛减小其偏差,通过非相参积累减小其测距抖动提高稳定性。研究发现,OCOG算法的测距偏差主要由于入射角越大回波展宽越严重,低通滤波器边缘递减使得远距离端展宽部分的幅度减少。最后采用OCOG与质心估计法的融合来补偿距离偏差,仿真试验验证了该补偿算法的有效性。
The traditional sea surface echo processing algorithm and the frequency correction cannot be effectively applied to the land surface target echo, so the offset center of gravity(OCOG) method which has the advantage of strong robustness was studied. The performances of OCOG method, the centroid estimation method and the area center method were compared through simulation. The results showed that the performance of OCOG method was similar to that of the area center method, but the OCOG method was better for incident angle ranges from 25° to 60°. When the incident angle was less than 25°, the centroid estimation method had a large error, but when the angle was greater than 25°, it also had certain application value. An improved OCOG method was proposed in this paper. It reduced the deviation by the method of convergence of the center of gravity and reduced the jitter of the ranging by non-coherent accumulation. It was found that the deviation of the OCOG algorithm was related to the angle of the antenna and character of the low pass filter. The compensated function was obtained by fusion of OCOG and non-coherent accumulation, which was also verified by simulation experiments.
The traditional sea surface echo processing algorithm and the frequency correction cannot be effectively applied to the land surface target echo, so the offset center of gravity(OCOG) method which has the advantage of strong robustness was studied. The performances of OCOG method, the centroid estimation method and the area center method were compared through simulation. The results showed that the performance of OCOG method was similar to that of the area center method, but the OCOG method was better for incident angle ranges from 25° to 60°. When the incident angle was less than 25°, the centroid estimation method had a large error, but when the angle was greater than 25°, it also had certain application value. An improved OCOG method was proposed in this paper. It reduced the deviation by the method of convergence of the center of gravity and reduced the jitter of the ranging by non-coherent accumulation. It was found that the deviation of the OCOG algorithm was related to the angle of the antenna and character of the low pass filter. The compensated function was obtained by fusion of OCOG and non-coherent accumulation, which was also verified by simulation experiments.
引文
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[4] 王志森,姜景山.一种鲁棒性雷达高度计跟踪算法的研究[J].电子学报,2003,31(3):341-344.Wang Z S,Jiang J S.Research on a robust radar altimeter tracking algorithm [J].ACTA Electronica Sinica,2003,31(3):341-344.(in Chinese)
[5] 马洪,李娜,张蕴玉.一种应用于地形匹配高度表中的回波跟踪与测高算法[J].宇航学报,2005,26(6):762-767.Ma H,Li N,Zhang Y Y.A tracking and height measuring algorithm applied to Tercom radar altimeter [J].Journal of Astronautics,2005,26(6):762-767.(in Chinese)
[6] 周先军,胡修林,马洪,等.星载雷达高度计OCOG算法性能研究[J].华中科技大学学报:自然科学版,2005,33(3):33-35.Zhou X J,Hu X L,Ma H,et al.The performance of OCOG algorithm of spaceborne altimeter[J].Huazhong Univ.of Sci.& Tech.:Nature Science Edition,2005,33(3):33-35.(in Chinese)
[7] 于涛,鞠德航.星载雷达高度计OCOG算法的改进[J].宇航学报,1992,(3):92-98.Yu T,Ju D H.An improvement on OCOG algorithm in satellite radar altimeter[J].Journal of Astronautics,1992,(3):92-98.(in Chinese)
[8] 刘浩淼,卞树檀,宋承文.脉冲多普勒高度计地面回波的建模与仿真[J].四川兵工学报,2011,32 (3):136-138.Liu H M,Bian S T,Song C W.Modeling and simulation of ground echo of pulse doppler altimeter[J].Journal of Sichuan ordnance industry,2011,32 (3):136-138.(in Chinese)
[9] 朱保安.月面探测器回波模拟方法研究[D].西安:西安电子科技大学,2013.Zhu B A.Research of Lunar Lander Echo Simulation Method[D].Xi’an:Xidian University,2013.(in Chinese)
[10] 张蕴玉,胡炜,刘柳,等.宽波束雷达高度表的回波波形特性分析及仿真[J].华中科技大学学报,2001,29(8):32-35.Zhang Y Y,Hu W,Liu L.The characteristic analysis of echo on the radar altimeter with beam and its simulation [J].Huazhong Univ.of Sci.& Tech.,2001,29(8):32-35.(in Chinese)
[11] 朱振军,林明,宋月明.起伏目标下的非相参积累[J].计算机工程与应用,2014,50(2):208-230.Zhu Z J,Lin M,Song Y M.Research of non-coherent integration under fluctuating targets[J].Computer Engineering and Applications,2014,50(2):208-230.(in Chinese)