Research On Parameter Correction Method Of Tree Radar Unit

As an efficient shallow detection method,Tree Radar Unit has many advantages,such as simple and flexible operation,intuitive profile,nondestructive and so on.It is found that Tree Radar Unit is affected greatly by the water content.In this study,we study the optimal parameters combination(Gain and Dielectric constant)of Tree Radar Unit in different water content media,in order to improve the accuracy of Tree Radar Unit in root detecting.We studied the parameters and resolution of Tree Radar Unit by means of burying roots in three mediums: sand(the volumetric water content 3.575%),farmland(the volumetric water content 29.293%)and wasteland(the volumetric water content 16.03%),the main results are as follows.1.In the default dielectric constant,Tree Radar Unit have large detection error of the depth of roots.In 10,20,30,40,50,60,80 centimeters of soil layer,the average detection error of the three media were 2.71,9.21,14.21,19.80,24.52,29.21,33.65,39.38 centimeters in three different water content medium;After the dielectric constant correction,the detection error of the depth of root of Tree Radar Unit from 10~80 centimeters of soil layer in sand is±1.5 centimeters,the detection error of root depth in farmland is-1.09~12.43 centimeters,the detection error of root depth in wasteland is-1.62~5.37 centimeters.After the correction of the dielectric constant,the root position of the detection of Tree Radar Unit is almost the same as the actual root position in dry sand,the correction effect is very good;in the moist farmland,the errors 900 MHz antenna and 400 MHz antenna are reduced,but the results are generally;in the natural wasteland,900 MHz antenna and 400 MHz antenna are all achieved great results,it is slightly better than the detection effect of farmland,but also not as good as in the sand.2.In the dry sand,Tree Radar Unit has very consistent relationship between the test results of different depth of root and the dielectric constant.From 10~80 centimeters of the soil,the root depth of the detection of Tree Radar Unit are all decreasing with the increasing of dielectric constant.The deeper the root is buried,the faster the detection result decrease;In higher water content farmland and wasteland,the relationship between the depth of roots and the dielectric constant is not consistent.Within 40 centimeters of soil layer,Tree Radar Unit has the less attenuation when electromagnetic wave is throughing the soil.But below the 40 centimeters of soil,the attenuation is very serious when the electromagnetic wave is throughing the soil,and the deeper the soil,the more serious deterioration.3.Tree Radar Unit have the the best detection result in dry sand.It can detect roots whose diameter is larger than 1.2 centimeters.It has the higher resolution and uniform profile.The root image of sand is very clear.In moist farmland,the detection effect of Tree Radar Unit is the worst in three mediums.It can only detect roots whose diameter is larger than 2.6 centimeters.The detection effect in the grass is slightly worsen than in the sand,but it is better than in the farmland.In natural sand,the resolution of 400 MHz antenna and 900 MHz antenna are similar.But the resolution of 400 MHz antenna is higher than 900 MHz antenna in farmland and wasteland.After parameter correcting,Tree Radar Unit can get better results in all three mediums.4.In the acquiescent parameters,Tree Radar Unit have too-small gain when the depth is less than 40 centimeters(the Minimum gain can up to-20 d B),but too-large gain when the depth is greater than 40 centimeters(the Maximum gain can up to 68 dB).The upper strata of formed profile is too light for recognition,but the lower stratum of formed profile is too dark and the clutter is too strong to identify the roots.After parameter correcting,GP1,GP2 of 900 MHz antenna are both range in 1~4 dB,GP3,GP4,GP5 of 900 MHz antenna are controlled in 23~39 dB.GP1,GP2 of 400 MHz antenna are both range in-12~-9 dB,GP3,GP4,GP5 of 400 MHz antenna are controlled in 16~38 dB.The color of formed profile is comparatively homogeneous,especially highlight the roots in the profile.The image is clear and easy to analyze.It has played a significant role in the further study of the roots.5.At the same depth of soil,the larger the diameter of root,the wider the opening of hyperbolic;At different depths of soil,the deeper the root,the more obscure the image is.When using 900 MHz antenna to detect root,the interval between the two roots in the horizontal direction is at least 15 centimeters and the distance between the two roots in the vertical direction is at least 10 centimeters;then Tree Radar Unit can detect those roots.When using 400 MHz antenna to detect root,the interval between the two roots in the horizontal direction is at least 20 centimeters and the distance between the two roots in the vertical direction is at least 15 centimeters;then Tree Radar Unit can detect those roots.