TRU树木雷达参数校正方法研究

发布时间：2018-01-20 17:02

本文关键词： 树木雷达参数校正介质根系　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：TRU作为高效的浅层探测方法,具有操作简单灵活、剖面直观、无损性等优点,在检测根系时受到很多外界因素的影响,研究发现,TRU受含水量的影响非常大。本研究以不同含水量介质为研究对象,对TRU在不同含水量介质中的最佳参数组合(系统增益和介电常数)进行研究,以期提高TRU根系检测的准确性。通过人为埋根的方式对不同含水量的三种介质:沙地(含水量3.575%)、农田(含水量29.293%)、荒地(含水量16.03%)中TRU的参数及其分辨率进行研究,主要得到以下研究结果:1.默认介电常数下根系深度检测值误差很大,在土层10、20、30、40、50、60、70、80 cm,TRU在三种介质的检测误差平均值分别为7.29、10.79、15.79、20.20、25.48、30.79、36.35、40.62 cm;经过介电常数校正以后,TRU在沙地中从土层10~80 cm根系检测深度误差都在±1.5 cm以内、在农田中为-1.09~12.43 cm、在荒地中为-1.62~5.37cm。校正介电常数以后,TRU在干燥沙地中检测到的根系位置与埋根深度几乎相同,校正效果非常好;在湿润农田中,900MHz和400MHz天线误差都减小,但效果一般;在荒地中,两种天线都取得了很大的成效,比农田中的检测效果略好,但也不及沙地。2.在干燥沙地中,不同埋深根系的检测结果与介电常数之间的关系非常一致,从土层10~80 cm,TRU所检测到的根系深度都随着介电常数的增大而减小,埋根越深,减小越快;而在含水量较大的农田和荒地中,根系深度与介电常数之间的关系并不一致,在土层40 cm以上,电磁波穿透土层时衰减较少,而在40 cm以下,电磁波穿越土层时衰减较严重,且土层越深,衰减越严重。3.TRU在干燥的沙地中检测效果最好,可检测到直径1.2 cm以上的根系,分辨率较高,剖面图均匀,根系图像非常清晰。在湿润的农田中检测效果最差,只能检测到直径2.6 cm以上的根系,在荒地中的检测结果较沙地略差,但比农田中效果略好。400MHz天线在沙地中的分辨率与900MHz相近,但在农田和荒地中分辨率比900MHz天线略高,TRU在三种介质中的参数经过校正后均可得到较好的结果。4.TRU在默认参数下检测时土层40 cm以上增益过小(最小可达-20 dB),而40 cm以下增益过大(最大可达68 dB),形成的剖面图上层图像颜色太浅无法识别,下层颜色太深、杂波影响太大难以辨别。经过参数校正以后,900MHz天线的增益值GP1、GP2的取值范围都在1~4 dB,GP3、GP4、GP5控制在23~39 dB之间,400MHz天线的GP1、GP2的取值范围在-12~-9 dB,GP3、GP4、GP5控制在16~38 dB之间,剖面图颜色较为均匀,并着重将植物根系突显出来,图像清晰易于分析观察,对进一步研究根系起到了很大的作用。5.在同一深度,根系直径越大,“双曲线”开口越宽;在不同深度,根系越深,“双曲线”图像越模糊。使用900MHz天线检测根系时,水平方向两条根系之间的间隔至少在15 cm以上,垂直方向两条根系之间的距离至少为10 cm以上才能分辨出来;而400MHz天线在检测时,水平方向两条根系之间的间隔20 cm以上,垂直方向两条根系之间的距离至少为15 cm以上,才能分辨出来。
[Abstract]:TRU as a shallow detection method is efficient, with simple and flexible operation, and has the advantages of intuitive profile, nondestructive detection, the root system is affected by many external factors, the study found that TRU was affected by the water content is very large. In this study, different water content medium as the research object, the TRU in different with the best combination of parameters water medium (system gain and dielectric constant) were studied, in order to improve the accuracy of TRU detection. Through the artificial root root buried way of three kinds of medium with different water content: the sand (3.575% water content), farmland (water content 29.293%), wasteland (16.03% water content) parameters and resolution TRU the main research results are as follows: 1. the default root depth of dielectric constant under the detection value of large error in the depth of 10,20,30,40,50,60,70,80, cm, TRU in three kinds of medium detection error average was 7.29,10.79,15.79,20. 20,25.48,30.79,36.35,40.62 cm; after the dielectric constant correction, TRU in sandy soil of 10~80 cm depth error from the root detection are - less than 1.5 cm, in the field of -1.09~12.43 cm, after the correction of the dielectric constant is -1.62~5.37cm. in the wasteland, TRU in dry sand detected the root location and buried depth of root is almost the same correction, the effect is very good; in the humid farmland, the 900MHz and 400MHz antenna errors are reduced, but the general effect; in the wasteland, two kinds of antennas have achieved great results, slightly better than the detection effect of farmland, but also not in the dry sand and sandy.2., very consistent relationship between different testing results the depth of the root and the dielectric constant of 10~80 cm from soil, root depth TRU detected increases with the decrease of dielectric constant, root buried deeper, decreased more rapidly; while in the higher water content of farmland and wasteland, The relationship between root depth and the dielectric constant is not consistent, in the depth of more than 40 cm, less attenuation of electromagnetic wave penetrating layer, and below 40 cm, the electromagnetic wave attenuation through the soil is serious, and the deeper soil, the more serious deterioration of.3.TRU detection in the dry sand in the best effect, can be detected in roots, more than 1.2 cm diameter high resolution profile uniform root image is very clear. The detection effect is the worst in the humid farmland, can only detect the root of more than 2.6 cm in diameter, detection in the wasteland were slightly worse than sand, but Tanaka is better in the sand in the resolution of the.400MHz antenna is similar to 900MHz but, in the resolution of farmland and wasteland is slightly higher than the 900MHz antenna, TRU in three kinds of medium parameters after calibration can obtain better results of detection of.4.TRU in the default parameters of soil above 40 cm (minimum gain is too small Up to -20 dB), and 40 cm high gain (up to 68 dB), the color profile of upper image formation is too shallow for recognition, the lower the color is too deep, too difficult to distinguish the influence of clutter. After calibration, the 900MHz antenna gain value GP1, the range of GP2 in 1~4 dB GP3, GP4, GP5, 23~39 in control dB, 400MHz antenna GP1, the range of GP2 -12~-9 in dB, GP3, GP4, GP5 in 16~38 dB, the color profile is uniform, and the roots of plants exposed, the image is clear and easy to be observed and analyzed for the further study on the root system played a big the role of.5. in the same depth, the greater the root diameter, "hyperbolic" opening wider; in different depth, the deeper roots, "hyperbolic" more blurred images. Using the 900MHz antenna detection root, between two horizontal root interval of at least 15 cm, vertical direction two The distance between the roots is at least 10 cm to distinguish. When the 400MHz antenna is detected, the interval between the two roots in the horizontal direction is more than 20 cm, and the distance between the two roots in the vertical direction is at least 15 cm, so that we can distinguish it.

【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN959;S718.4

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