摘要
对雷达电波大气折射及误差修正问题的研究由来已久,并且国内外都已取得了一定的成果,尤其是近些年,随着电子测量系统硬件精度的进一步提高,以及数据处理方法的进一步优化,外测设备本身的误差大大降低,大气引起的电波折射误差就成为限制雷达系统实现最高精度测量的关键因素之一。因此,加强电波折射误差修正方法的研究并设计出高效的修正系统,对提高雷达系统的测量精度、促进国防和现代工农业生产的发展具有十分重要的意义。
本文首先从理论上分析了电波折射效应及其对雷达测量参数的影响,以及大气折射率修正模型,通过比较几种常用的大气折射修正方法,本文采用基于地面参数预测的分段模型,在不考虑大气水平不均匀性时,在每段中又进行线性分层,进一步提高对折射误差的修正。
针对下垫面复杂地区,即考虑大气的水平不均匀性,由于它对低层大气的折射误差影响较大,对高层大气的影响很小,为了进一步减小修正误差,提出混合分段模型,即根据下垫面复杂程度,把对流层分成高层和低层。对低层大气空间结构采用区域法进行研究,在得到大气折射率剖面之后,折射误差修正则采用射线规范方程法。忽略水平不均匀性对高层大气折射误差的影响,对高层大气折射则仍然采用上面的基于地面参数预测的折射修正方法。
通过运用上述方法对某山区两个季节两种天气情况下的测量数据进行误差修正,并分别与射线描迹法和对流层微波辐射计法的修正结果对比后得出结论,本文提出的折射误差修正方法可在一定范围内、一定条件下完成折射距离、仰角的修正,并达到了修正的预期目的。
最后总结这种方法的适用条件及其优缺点,并对下垫面复杂地区折射误差修正的下一步努力方向进行了展望。
The research on astronomical refraction and error correction of radar wave has long been undertaken in China and abroad. Recent years, more and more outcomes have been achieved due to the upgrades of electronic measurement hardware and the optimization of data processing methods. With the reduction of error probability of external measurement equipment, the error caused by astronomical refraction thus becomes one of the key factors that affect the precision of radar measurement system. Therefore, to strengthen the research on the refractive error correction of radar wave and so as to design an efficient correction system is of great significance to improving the precision of radar measurement and promoting the modernization of national defense, industry and agriculture.
The thesis starts with a theoretical analysis of radar wave refraction effect, its impact on the measurement parameter of radar, and of the models of astronomical refraction rate correction. Upon comparison of several commonly-used methods for astronomical refraction correction, the author adopts the piecewise model of ground-based parameter prediction which hypothesizes the atmosphere is homogenous and delaminates linearly each section to improve the correction of refraction error.
As for the area where atmospheric underlying surface is non-uniform, that is, where the atmosphere is inhomogeneous, considering that the refraction error is more evident in the lower atmosphere than in the upper one, a mixed sectional model is designed to further reduce the error probability. According to the model, the troposphere is divided into upper and lower layers. The spatial structure of lower layers is investigated by field method. Refraction error correction is actualized by the method of radial normal equation referring to refractive index profile of atmosphere. To correct the refraction error in upper atmosphere and neglect its heterogeneity, the above-mentioned ground-based parameter prediction method is followed.
By comparing the corrected results obtained by the above-mentioned methods with those obtained by ray tracing method and troposphere microwave radiometer method under two climate conditions of two seasons in the same mountainous area, the author concludes that the proposed methods for refraction error correction is quite feasible in given areas and conditions for the correction of refractive distance and elevation angle.
At the end of the thesis, the application condition and relative merits of the methods are given and the outlook for the atmospheric refraction error correction above a non-uniform underlaying surface is presented.
引文
[1]谢晨波,周军,岳古明等.新型车载式拉曼激光雷达测量对流层水汽.光学学报, 2006,26(09):1281~1286
[2]熊皓.磁波传播与空间环境.北京:电子工业出版社,2004.18~136
[3] Weibrod and Anderson.Simple method for computing troposphere and lonospheric refractive effects on radio wave.PIRE,1959,47(10):1770~1777
[4] Gardiner C. The Troposphere and its Influence on Spacecraft Tracking, Goddard Space Flight Center.Greenbelt,Maryland:1964,AD-441576
[5] Rowlandson L G and Herlihy J R. Refraction-Induced Tracking Errors and Correction Methods for the Air Force Western Test Range.AD-682998
[6] H.S.Hopfield.Two-Quartic Troposphere Refractivity Profile for correcting Satellite Data.J.G.R,1969,74(18):4487
[7]张瑜,程显海.电波折射误差修正精度的检验方法研究.空间电子技术,1998(1)
[8]张瑜.用辐射计进行低角电波折射修正的补偿方法.微波学报,2001,17(1): 96~98
[9]韩文焌.对有效地球半径的诠释.电波科学学报,1998,13(4):368~370
[10]熊皓,王爱玲.关于等效地球半径的概念和定义问题.电波科学学报,1997,12(1): 10~14
[11]田玉庶,王健.等效地球半径经典公式推导与应用中的某些数学问题.电波科学学报,2004,19(增刊):221~226
[12]张瑜,杨伏林.59型探空仪对折射修正精度的限制.电波科学学报,2001,16(3):407~413
[13]孟庆海,张瑜.折射率公式对电波折射修正精度的限制.电波科学学报,2003, 18(6):710~711
[14]张祖荫.微波辐射计测量技术及应用.北京:电子工业出版社,1995.15~167
[15]张祖荫.微波辐射计测量技术及应用.北京:电子工业出版社,1995.21~258
[16]郭丽.用双通道微波辐射计测量反演大气折射率剖面.雷达科学与技术,2003, 1(3):161~169
[17]程显海.微波辐射计在电波折射修正中的应用.微波学报,1995,11(1):61-65
[18]黄捷,马兴图.任意对流层定位误差的计算.电波与天线,1974,(2):1~13
[19]江长荫.低仰角无线电定位测速的大气层电波传播误差.电波与天线,1982,(1): 1~62
[20]江长荫.任意大气层折射误差的实用修正方法.电子学报,1999,(3):45-48
[21]黄捷.电波大气折射误差修正.北京:国防工业出版社,1999.88~256
[22]朱丽娜,张瑜.下垫面复杂地区大气结构探测新方法—区域法.河南师范大学学报,2007(3):64-66
[23]张瑜.下垫面复杂地区对流层电波时延的精确实时测量.探测和控制学报, 2007(3):65-68
[24]张仁芳,吕志孔,黄汝言.电离层折射效应技术表示法的估算.空间物理论文集,北京:科学出版社,1980:218-233
[25]张仁芳,权坤海.电离层探测卫星资料的联合分析.电波与天线,1984(2)
[26]张仁芳.电离层分片换算法中谷的处理.空间科学学报,1987,7(2)
[27]张仁芳.电离层对高频无线电波多普勒频移的影响.飞行器测控技术,1989,4:17-23
[28] Barton D K.Ward H R.Handbook of radar measurement.1969:91~128
[29]毛田,万卫星,孙凌峰.用Kriging方法构建中纬度区域电离层TEC地图.空间科学学报,2007,27(04):279~285
[30] Smith,E.K.,S.Weintraub. The constants in the equation for atmospheric refractive index at radiofrequencies,Proc.IRE,41:1035~1037
[31] B.R.Bean and E. J. Dutton. Radio Metorology, Dover Publications.Inc. New York,1966.169~228
[32] G.D.Thayer. A modified equation for radio refractivity of air. Radio science,1974, 9(10):803~807
[33]蔺发军,刘成国,杨玉萍等.基于Windows平台的微波折射率仪数据采集系统.电波科学学报,2003,18(5):575~578
[34]左营喜,贾瑞进,徐之材.用于折射率仪的高Q腔谐振频率跟踪系统.电波科学学报,1998,13(1):103~105
[35] Hopfield.H.S.Troposphere effect on electromagnetic measured range:Prediction from surface weather data.Radio Science,1971,6(3):385~408
[36]黄捷.无线电测速定位的对流层电波传播误差.电波与天线,1973,(3~4):10~28
[37] B.R.Bean,B.A.Cahoon,C.A.Samson et al.A World Atlas of Aimospheric Radio Refractivity.Washington D.C.:U.S.Goverment Printing Office,1966.120~298
[38] J.M.Kelso.Radio Ray Propagation in the Ionosphere.New York:McGraw-Hill Book Company,1964.26~129
[39]谢益溪.电波传播—超短波、微波、毫米波.北京:电子工业出版社,1990.22~209
[40]张瑜,高霞.低空大气电波时延和弯曲对无线电定位的影响.电子技术与信息化,1996,1(3):54~59
[41]沙踪.电波传播的研究与应用.第七届电波传播论文集,2004
[42]张瑜.三维大气电波折射修正的试验研究.电波科学学报,1996,11(4):82~86
[43]张瑜.电磁波空间传播.西安:西安电子科技大学出版社,2007.27~193
[44] K.G. Budden.Radio Waves in the Ionosphere. Cambridge: Cambridge University Press,1961:271-282
[45] K.G. Budden. The Propagation of Radio Waves—Theory of Radio Waves of Low Power in the Ionosphere and Magnetosphere. Cambridge: Cambridge University Press,1985:403-409
[46]江长荫,王被德.机载与星载雷达的电波传播大气折射修正.中国科学(E辑) ,2001,31 (1) :19-27
[47]李兰,程显海.用作对流层折射修正的双频微波辐射计最佳频率选择[C] .第四届全国电波传播会议论文集[A ] .新乡:1991
