CN111812725A - Ground penetrating radar and soil moisture measuring method - Google Patents
Ground penetrating radar and soil moisture measuring method Download PDFInfo
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Abstract
The invention provides a ground penetrating radar and a soil moisture measuring method, wherein the ground penetrating radar comprises a supporting platform, a transmitting antenna, a receiving antenna and a display; the supporting platform is provided with traveling wheels, so that the supporting platform can move on the surface of the soil to be measured through the traveling wheels, the transmitting antenna and the receiving antenna can be fixed on the supporting platform, and the receiving antenna is electrically connected with the display; the transmitting antenna transmits electromagnetic waves, and the receiving antenna can receive the electromagnetic waves transmitted by the transmitting antenna and transmit the wave speed of the received electromagnetic waves to the display to be displayed. The invention has the advantages of high measuring speed, stable verification result, small chance, high reliability and no damage to the soil structure.
Description
Technical Field
The invention relates to the technical field of soil monitoring, in particular to a ground penetrating radar and a soil moisture measuring method.
Background
The soil water content is closely related to precipitation, evapotranspiration, irrigation and crop growth, plays an important role in hydrologic cycle, and is a source for crops to live. Too low a water content in the soil can affect the nutrient absorption of crops, cause soil erosion, aggravate insect pests and further affect the growth and health of the crops. Therefore, the soil water content is accurately and effectively monitored. The method has important significance for crop yield prediction, drought monitoring and evaluation, pest control and irrigation management.
With the rapid development of remote sensing technology, satellite remote sensing can obtain high-resolution and real-time surface soil water information, and becomes an important means for monitoring soil water in a large range. High-resolution soil and aquatic products based on satellite remote sensing are widely used for identifying and evaluating agricultural drought, for example, Landsat series with spatial resolution of 30m and HJ-1 satellite data are common domestic remote sensing data sources. The precision and reliability of the soil water remote sensing monitoring results need to be verified by ground measured data. At present, the soil water remote sensing monitoring result is usually verified by collecting a soil sample, drying the soil sample to obtain soil water data, and comparing the result with the remote sensing monitoring result to verify the remote sensing monitoring result. Such an approach has the disadvantages of being time consuming, labor intensive and damaging to the soil structure.
Chinese patent publication No. CN208026734U discloses a soil moisture content measuring device, which is particularly adapted to measure moisture in soil by inserting a first moisture detector, a second moisture detector and a third moisture detector into soil, and in such a manner that three moisture detectors need to be inserted into soil at different positions when measuring moisture of a certain range of soil, which is very inconvenient to operate.
Disclosure of Invention
The invention aims to provide a ground penetrating radar for verifying a soil water remote sensing monitoring result and a soil water measuring method, which have the advantages of high measuring speed, stable verification result, small chance and high reliability.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a ground penetrating radar is used for measuring soil moisture and comprises a supporting platform, a transmitting antenna, a receiving antenna and a display;
travelling wheels are arranged on the supporting platform, so that the supporting platform can move on the surface of soil to be measured through the travelling wheels, the transmitting antenna and the receiving antenna can be fixed on the supporting platform, and the receiving antenna is electrically connected with the display;
the transmitting antenna transmits electromagnetic waves, the receiving antenna can receive the electromagnetic waves transmitted by the transmitting antenna and transmit the wave speed of the received electromagnetic waves to the display to be displayed, and the receiving antenna receives the electromagnetic waves transmitted by the transmitting antenna and comprises air waves and ground direct waves.
Preferably, the material of the supporting platform is plastic.
Preferably, the device also comprises a handle fixedly connected with the supporting platform;
the handle and the travelling wheels are respectively positioned at two ends of the supporting platform.
Preferably, the device also comprises a supporting shaft and a mounting rod;
the axis of the supporting shaft is vertical to the upper surface of the supporting platform, one end of the supporting shaft is fixedly connected to the upper surface of the supporting platform, the other end of the supporting shaft is fixedly connected to the middle of the mounting rod, and the axis of the mounting rod is vertical to the axis of the supporting shaft, so that the mounting rod and the supporting shaft form a T shape;
the edge the axis direction of installation pole, the installation pole is located the part of back shaft both sides is first installation department and second installation department respectively, receiving antenna installs on the first installation department, transmitting antenna installs on the second installation department.
Preferably, the antenna further comprises a first fixing nut and a first connecting rod fixedly connected with the receiving antenna;
the first connecting rod is provided with a first through hole, and the first connecting rod is sleeved on the first mounting part through the first through hole;
be provided with on the first installation department with first fixation nut assorted first screw thread, first fixation nut's quantity is two, two equal threaded connection of first fixation nut is in on the first installation department, and follow the axis direction of installation pole, two first fixation nut is located the both sides of head rod, so that two first fixation nut can be through the effect of screwing will the head rod is fixed on the first installation department.
Preferably, the antenna further comprises a second fixing nut and a second connecting rod fixedly connected with the transmitting antenna;
the second connecting rod is provided with a second through hole, and the second connecting rod is sleeved on the second mounting part through the second through hole;
be provided with on the second installation department with second fixation nut assorted second screw thread, second fixation nut's quantity is two, two equal threaded connection of second fixation nut is in on the second installation department, and follow the axis direction of installation pole, two second fixation nut is located the both sides of second connecting rod, so that two second fixation nut can be through the effect of screwing will the second connecting rod is fixed on the second installation department.
A method for measuring soil moisture, using the ground penetrating radar with any technical characteristics;
the method comprises the following steps:
s100, moving the ground penetrating radar, and enabling a transmitting antenna to transmit electromagnetic waves;
s200, the receiving antenna receives the electromagnetic wave transmitted by the transmitting antenna, transmits the wave speed information of the received electromagnetic wave to a display for displaying, and calculates the wave speed V of the electromagnetic wave according to the wave speed informationGW；
S300, according to the wave velocity V of the electromagnetic wave displayed on the displayGWAnd calculating the water content theta of the soil.
Preferably, in step S300, θ ═ 0.053+ 0.0293-0.000552+0.00000433Wherein is the dielectric constant;
＝(c/VGW)2where c is the propagation velocity of the electromagnetic wave in air.
Preferably, step S100 includes: adjusting a distance x between the transmitting antenna and the receiving antenna;
in step S300, the electromagnetic waves received by the receiving antenna and transmitted by the transmitting antenna include an air wave and a ground direct wave, and the wave velocity t of the air wave is calculated according to the wave velocity information of the air wave displayed on the displayAWAnd simultaneously calculating the wave velocity t of the ground direct wave according to the wave velocity of the ground direct wave displayed on a displayGWAnd V isGW＝x/(tGW-tAW+x/c)。
Preferably, step S100 includes: and adjusting the distance x between the transmitting antenna and the receiving antenna, and fixing the transmitting antenna and the receiving antenna on the supporting platform when x reaches a reasonable value, wherein x is more than or equal to 1.2 meters and less than or equal to 1.8 meters.
Preferably, when the ground penetrating radar further comprises a support shaft, a mounting rod, a first fixing nut and a first connecting rod fixedly connected with the receiving antenna;
step S100 includes: and moving the receiving antenna along the axial direction of the mounting rod to adjust the distance x between the transmitting antenna and the receiving antenna, and when x reaches a reasonable value, fixing a first connecting rod on the mounting rod through the first fixing nut, wherein x is more than or equal to 0.38 m and less than or equal to 5 m.
Preferably, when the ground penetrating radar further comprises a support shaft, a mounting rod, a first fixing nut, a first connecting rod fixedly connected with the receiving antenna, a second fixing nut and a second connecting rod fixedly connected with the transmitting antenna;
step S100 includes: moving the receiving antenna and the transmitting antenna along the axial direction of the mounting rod to adjust the distance x between the transmitting antenna and the receiving antenna, when x reaches a reasonable value, fixing a first connecting rod on the mounting rod through the first fixing nut, and fixing a second connecting rod on the mounting rod through the second fixing nut;
in the axial direction of the mounting rod, the distance between the transmitting antenna and the axial line of the supporting shaft is equal to the distance between the receiving antenna and the axial line of the supporting shaft, wherein x is more than or equal to 0.38 m and less than or equal to 5 m.
Preferably, the ground area to be measured is rectangular;
in step S100, the moving path of the ground penetrating radar includes a first path and a second path, and the first path and the second path are two diagonal lines of the operation.
Preferably, in step S100, the moving path of the ground penetrating radar includes at least one third path located inside the rectangle, and the third path is parallel to the first path;
and/or in step S100, the moving path of the ground penetrating radar includes at least one fourth path, and the fourth path is parallel to the second path.
Preferably, the measured ground area is a rectangle, and the rectangle comprises a first side line and a second side line which are perpendicular to each other;
in step S100, the moving path of the ground penetrating radar includes a fifth path and a sixth path located inside the rectangle, the fifth path is parallel to the first edge, and the sixth path is parallel to the second edge.
Preferably, the number of the fifth paths is at least two and/or the number of the sixth paths is at least two.
According to the technical scheme, the ground penetrating radar transmits the electromagnetic waves by the transmitting antenna, and the receiving antenna can receive the electromagnetic waves transmitted by the transmitting antenna and transmit the wave speed of the received electromagnetic waves to the display to be displayed, so that the water content of the soil can be calculated according to the wave speed of the electromagnetic waves displayed by the display.
Drawings
Fig. 1 is a schematic structural diagram of a ground penetrating radar according to an embodiment of the first embodiment;
FIG. 2 is a right side view of FIG. 1;
FIG. 3 is an enlarged view of portion A of FIG. 1;
fig. 4 is a diagram illustrating a method for measuring soil moisture in example two.
FIG. 5 is a diagram of a transmission route of an electric measuring wave emitted by a transmitting antenna in soil;
FIG. 6 is a schematic diagram of a measurement path of a first mode ground penetrating radar;
fig. 7 is a schematic diagram of a measurement path of a ground penetrating radar in a second mode.
In the figure: 1-a support platform; 11-a travelling wheel; 12-a handle; 2-a transmitting antenna; 3-a receiving antenna; 4-supporting the shaft; 5, mounting a rod; 51-a first mounting portion; 52-a second mounting portion; 6-a first fixing nut; 7-a first connecting rod; 71-a first via; 8-a second fixing nut; 9-a second connecting rod; 100-ground area to be measured; 101-a first path; 102-a second path; 103-a third path; 104-a fourth path; 105-a fifth path; 106-sixth path; 107-a first edge; 108-second edge line.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly apparent, the pipe connection structure and the microchannel heat exchanger according to the present invention will be described in further detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example one
As shown in fig. 1 and 2, a ground penetrating radar for measuring soil moisture includes a support platform 1, a transmitting antenna 2, a receiving antenna 3 and a display (not shown). Be provided with travelling wheel 11 on supporting platform 1, make supporting platform 1 can move on the surface of the soil that awaits measuring through travelling wheel 11, transmitting antenna 2 and receiving antenna 3 homoenergetic are fixed on supporting platform 1, and receiving antenna 3 is connected with the display electricity. The transmitting antenna 2 transmits electromagnetic waves, and the receiving antenna 3 can receive the electromagnetic waves transmitted by the transmitting antenna 2 and transmit the wave speed of the received electromagnetic waves to the display for display.
During the in-service use, measurement personnel can drive supporting platform 1 and drive travelling wheel 11 and remove on the surface of the soil that awaits measuring, makes transmitting antenna 2 transmission electromagnetic wave simultaneously, and receiving antenna 3 can receive the electromagnetic wave that transmitting antenna 2 sent at this moment. An operator can bring the display on the body or any position capable of realizing real-time monitoring, monitor the wave velocity of the electromagnetic wave received by the receiving antenna 3 in real time, and calculate the moisture content of the soil according to the monitored wave velocity of the electromagnetic wave (for a specific calculation method, see embodiment two), it should be noted that the electromagnetic wave received by the receiving antenna 3 and transmitted by the transmitting antenna 2 includes an air wave and a ground direct wave. Compared with the prior art, the method has the advantages of high measuring speed, stable verification result, small chance, high reliability and no damage to the soil structure.
In actual manufacturing, in order to prevent the supporting platform from interfering with the transmission of electromagnetic waves, the supporting platform 1 may be made of plastic or other materials that cannot block electromagnetic waves.
Further, as shown in fig. 1 and 2, the device further comprises a handle 12 fixedly connected with the supporting platform 1, wherein the handle 12 and the traveling wheels 11 are respectively located at two ends of the supporting platform 1. Therefore, the operator can pull the handle 12 to enable the supporting platform 1 to move on the surface of the soil to be measured through the travelling wheels 11, the operation is simple and convenient, and the working efficiency is improved.
As an embodiment, as shown in fig. 1 and 2, a support shaft 4 and a mounting rod 5 are further included. The axis of back shaft 4 is perpendicular with the upper surface of supporting platform 1 to one end fixed connection is on the upper surface of supporting platform 1, and other end fixed connection is in the middle part of installation pole 5, and the axis of installation pole 5 is perpendicular with the axis of back shaft 4, makes installation pole 5 and back shaft 4 form the T font. In the axial direction of the mounting rod 5, the portions of the mounting rod 5 on both sides of the support shaft 4 are a first mounting portion 51 and a second mounting portion 52, respectively, the receiving antenna 3 is mounted on the first mounting portion 51, and the transmitting antenna 2 is mounted on the second mounting portion 52. Therefore, a reasonable distance exists between the transmitting antenna 2 and the receiving antenna 3 to adapt to the requirement of measurement work, and the accuracy of the measurement effect is further ensured.
Optionally, as shown in fig. 1, 2 and 3, a first fixing nut 6 and a first connecting rod 7 fixedly connected to the receiving antenna 3 are further included. The first connecting rod 7 is provided with a first through hole 71, and the first connecting rod 7 is sleeved on the first mounting portion 51 through the first through hole 71. Be provided with on first installation department 51 with first fixation nut 6 assorted first screw thread, the quantity of first fixation nut 6 is two, and two equal threaded connection of first fixation nut 6 are on first installation department 51 to along the axis direction of installation pole 5, two first fixation nuts 6 are located the both sides of head rod 7, so that two first fixation nuts 6 can fix head rod 7 on first installation department 51 through the effect of screwing. By adopting the technical scheme, the position of the receiving antenna 3 can be adjusted along the axial direction of the mounting rod 5, when a reasonable distance is reached between the receiving antenna 3 and the transmitting antenna 2, the receiving antenna 3 is fixed through the two first fixing nuts 6, and the position of the transmitting antenna does not need to be adjusted by the adjusting mode.
Further, as shown in fig. 1, the antenna further comprises a second fixing nut 8 and a second connecting rod 9 fixedly connected with the transmitting antenna 2. The second connecting rod 9 is provided with a second through hole, and the second connecting rod 9 is sleeved on the second mounting portion 52 through the second through hole. Second threads matched with the second fixing nuts 8 are arranged on the second mounting portion 52, the number of the second fixing nuts 8 is two, the two second fixing nuts 8 are in threaded connection with the second mounting portion 52, and in the axial direction of the mounting rod 5, the two second fixing nuts 8 are located on two sides of the second connecting rod 9, so that the two second fixing nuts 8 can fix the second connecting rod 9 on the second mounting portion 52 through the screwing effect. By adopting the technical scheme, the positions of the transmitting antenna 2 and the receiving antenna 3 can be adjusted simultaneously along the axial direction of the mounting rod 5, when a reasonable distance is reached between the receiving antenna 3 and the transmitting antenna 2, the receiving antenna 3 is fixed through the two first fixing nuts 6, the transmitting antenna 2 is fixed through the two second fixing nuts 8, and during specific adjustment, the distance between the transmitting antenna 2 and the axial line of the supporting shaft 4 can be equal to the distance between the receiving antenna 3 and the axial line of the supporting shaft 4.
Example two
A soil moisture measuring method, a ground penetrating radar described in the first embodiment. The method comprises the following steps:
s100, moving the ground penetrating radar, and enabling a transmitting antenna to transmit electromagnetic waves;
s200, the receiving antenna receives the electromagnetic wave transmitted by the transmitting antenna, transmits the wave speed information of the received electromagnetic wave to a display for displaying, and calculates the wave speed V of the electromagnetic wave according to the wave speed informationGW；
S300, according to wave velocity V of electromagnetic waveGWAnd calculating the water content theta of the soil.
It should be noted that the wave velocity V of the electromagnetic wave is calculated from the wave velocity information displayed on the displayGWThe invention is not the point of the invention but a prior art, and the invention only utilizes the prior art, and does not intend to improve the prior art, so that the detailed description of the specific calculation method is not repeated here. By adopting the technical scheme, the water content theta of the soil can be measured only by moving the ground penetrating radar on the surface of the soil to be measured, the soil structure cannot be damaged, and meanwhile, the ground penetrating radar passes through the indicator in real timeWave velocity V of the displayed electromagnetic waveGWAnd the soil water content theta is calculated, and the method has the advantages of high measurement speed, stable verification result, small contingency, high reliability and the like.
Specifically, in step S300, θ ═ 0.053+ 0.0293-0.000552+0.00000433In which the dielectric constant is given. Wherein ═ c/VGW)2Where c is the propagation velocity of the electromagnetic wave in air. Further, step S100 includes: the distance x between the transmitting antenna and the receiving antenna is adjusted. As shown in fig. 5, in step S300, the electromagnetic wave transmitted by the transmitting antenna and received by the receiving antenna includes an air wave and a ground direct wave, so that the information displayed on the display includes the wave velocity information of the air wave and the wave velocity information of the ground direct wave, and the wave velocity t of the air wave is calculated according to the wave velocity information of the air wave displayed on the displayAWAnd simultaneously calculating the wave velocity t of the ground direct wave according to the wave velocity of the ground direct wave displayed on a displayGWAnd V isGW＝x/(tGW-tAW+x/c)。
In actual operation, the wave speed of the air wave displayed on the display is tAWThe wave velocity of the ground direct wave is tGWAll are velocity curves, so the distance x between the transmitting antenna and the receiving antenna needs to be adjusted to a reasonable value in order to be able to better distinguish the velocity curve of the air wave from the velocity curve of the ground direct wave. The following three methods can be adopted for the adjustment of the distance x between the transmitting antenna and the receiving antenna:
the first method is a fixed antenna spacing (FO) method, and when this method is used, step S100 includes: and adjusting the distance x between the transmitting antenna and the receiving antenna, and fixing the transmitting antenna and the receiving antenna on the supporting platform when x reaches a reasonable value. Wherein x is more than or equal to 1.2 meters and less than or equal to 1.8 meters. Because the measuring depth of the fixed antenna spacing method (FO) is generally less than 10cm, the measuring depth is consistent with the monitoring depth of a remote sensing product, and the method has the advantages of high measuring speed, high efficiency, high spatial resolution and the like, the fixed antenna spacing method (FO) is selected to measure the water content of the pixel soil. Fixed antenna spacing method (FO)Keeping the distance between the transmitting antenna and the receiving antenna unchanged, and measuring while moving in a line measuring mode to obtain the wave velocity of the ground direct wave. The fixed antenna spacing (FO) method uses the air wave velocity t according to the known distance x between the transmitting antenna and the receiving antennaAWAnd the ground direct wave tGWCalculating the wave velocity V of the ground direct electromagnetic waveGW。
The fixed antenna spacing method (FO) measures the spatial distribution of soil moisture content by extracting the ground direct wave and does not require the confirmation of the depth of the reflecting layer in advance. But before measurement, a reasonable antenna spacing x needs to be confirmed, so that the interference of air waves to ground direct waves is reduced, and the measurement accuracy is improved. In actual work, the value range of x is more than or equal to 1.2 meters and less than or equal to 1.8 meters, and preferably 1.5 meters.
The characteristics of the measurement depth (the depth is generally less than 20 cm) of the water content of the remote sensing soil and the measurement mode of the ground penetrating radar are comprehensively considered, and the 250MHz high-frequency ground penetrating radar is selected for measuring the water content of the soil with the pixel scale. The parameters of the fixed antenna spacing method (FO) are set as follows according to the measurement requirements:
ground penetrating radar measurement parameter setting
And for pixels of Landsat series and HJ-1 satellite images with the spatial resolution of 30m, defining a sample size of 30m multiplied by 30m at the corresponding position of the pixel to be verified in the target area, so that the sample size and the remote sensing pixel are basically overlapped. The soil moisture content in the sample is measured by using a fixed antenna spacing method (FO), but the fixed antenna spacing method (FO) is monitored in a line measuring mode, and reasonable line measuring number and arrangement method are needed in order to enable a measuring result to be close to the real average soil moisture content in the sample as far as possible. The invention provides two tested measurement path schemes of a ground penetrating radar:
in the first mode, as shown in fig. 6, the ground area 100 to be measured is rectangular. In step S100, the moving path of the ground penetrating radar includes a first path 101 and a second path 102, and the first path 101 and the second path 102 are two diagonal lines. Preferably, as shown in fig. 6, in step S100, the moving path of the ground penetrating radar includes at least one third path 103 located inside the rectangle, and the third path 103 is parallel to the first path 101; and/or, in step S100, the moving path of the ground penetrating radar includes at least one fourth path 104, and the fourth path 104 is parallel to the second path 102. By adopting the mode, the field experiment and the analysis of the random combination method prove that when the relative error is required to be within 7 percent, the confidence level of the measured value of the water content of the pixel soil can be ensured to be more than 90 percent by the measuring path layout scheme of the ground penetrating radar; under the same precision requirement, the method can better reflect the spatial change of the soil water content in the sample compared with the traditional point scale measurement method, and has smaller relative error.
In a second manner, as shown in fig. 7, the measured ground area 100 is a rectangle including a first side line 107 and a second side line 108 perpendicular to each other. In step S100, the moving path of the ground penetrating radar includes a fifth path 105 and a sixth path 106 located inside the rectangle, the fifth path 105 is parallel to the first edge 107, and the sixth path 106 is parallel to the second edge 108. Preferably, the number of fifth paths 105 is at least two and/or the number of sixth paths 106 is at least two. By adopting the mode, the field experiment and the analysis of the random combination method prove that when the relative error is required to be within 5 percent, the confidence level of the measured value of the water content of the pixel soil can be ensured to be more than 95 percent by the measuring path layout scheme of the ground penetrating radar; under the same precision requirement, the method can better reflect the spatial change of the soil water content in the sample compared with the traditional point scale measurement method, and has smaller relative error.
The method comprises the steps of measuring the soil water content in a sample according to a measurement path scheme of a ground penetrating radar with a pixel scale, wherein the difference between the GPR measurement time and the transit time of a remote sensing product to be verified is not more than 30 minutes, taking the average soil water content of the measurement result of the ground penetrating radar as the ground measurement result of the pixel corresponding to the sample, and evaluating the precision of the soil water remote sensing product through indexes such as relative error, absolute error and the like, so that the accuracy of ground verification can be effectively improved.
In particular to
The method comprises the steps of taking a water conservancy scientific research institute base in a water conservancy department and pastoral area as a research area (41 degrees 22 'N and 111 degrees 12' E), calculating a vegetation water supply index (VSWI) through a normalized vegetation index (NDVI) and a ground surface temperature (LST) by adopting a Landsat8 satellite image, establishing an empirical model of the VSWI and the soil water content, and inverting the soil water content theta of the research area, wherein the goodness of fit R2 of the model is 0.71, and the root mean square error is 0.0216m3/m 3. The soil moisture content θ is VSWI × 8.581-0.049, wherein the calculation of the VSWI value is not the inventive point of the present invention but the prior art, and therefore the manner of calculating it is not described in detail herein.
Four adjacent 30m multiplied by 30m sample squares are selected in a research area, and the soil water content remote sensing inversion result of 2016, 8, 24 days is subjected to ground verification by adopting a drying method based on a limited measuring point and the soil water content remote sensing monitoring ground verification method based on the ground penetrating radar, wherein the results are as follows.
Soil water content remote sensing product verification result comparison
From the table 2, it can be concluded that the ground verification method based on the remote sensing monitoring of the soil moisture content of the ground penetrating radar has more stable verification result and less chance.
The second method is a wide angle method (WARR), and according to the present embodiment, the ground penetrating radar further includes a support shaft, a mounting rod, a first fixing nut, and a first connecting rod fixedly connected to the receiving antenna. Step S100 includes: and moving the receiving antenna along the axial direction of the mounting rod to adjust the distance x between the transmitting antenna and the receiving antenna, and when x reaches a reasonable value, fixing the first connecting rod on the mounting rod through the first fixing nut, wherein x is more than or equal to 0.38 m and less than or equal to 5 m. Thus, the wave velocity V of the electromagnetic wave can be measured by increasing the distance x between the transmitting antenna and the receiving antennaGW。
The third method is a concentric process (CMP) method, and according to the embodiment, the ground penetrating radar further includes a support shaft, a mounting rod, a first fixing nut, and a second fixing nut fixedly connected to the receiving antennaThe first connecting rod, the second fixing nut and the second connecting rod are fixedly connected with the transmitting antenna. Step S100 includes: the receiving antenna and the transmitting antenna are moved along the axis direction of the mounting rod to adjust the distance x between the transmitting antenna and the receiving antenna, when x reaches a reasonable value, the first connecting rod is fixed on the mounting rod through the first fixing nut, and meanwhile, the second connecting rod is fixed on the mounting rod through the second fixing nut. In the axial direction of the mounting rod, the distance between the transmitting antenna and the axial line of the supporting shaft is equal to the distance between the receiving antenna and the axial line of the supporting shaft, wherein x is more than or equal to 0.38 m and less than or equal to 5 m. Thus, the wave velocity V of the electromagnetic wave can be measured by increasing the distance x between the transmitting antenna and the receiving antenna at equal intervalsGW. In the method, the distance x between the transmitting antenna and the receiving antenna may be increased, in particular in increments of 0.1 meter.
It should be noted that, when the fixed antenna spacing method (FO) is adopted, in a dry condition, when the distance x between the transmitting antenna and the receiving antenna is too small, the air wave and the ground direct wave interfere with each other, and therefore the arrival time of the air wave and the ground direct wave cannot be accurately extracted. When the distance x between the transmitting antenna and the receiving antenna is too large under a dry condition, the ground direct wave is easy to attenuate, the spatial resolution is relatively low, and the arrival time is inaccurate. Therefore, there is a need to determine the optimal x value by wide angle method (WARR) or co-Center Method (CMP) before applying the fixed antenna spacing method (FO) method so that t can be effectively distinguished and correctly identifiedGWAnd tAW。
The above embodiment is that the present invention has the following advantages: the method solves the problem that the ground verification of a soil water remote sensing product needs a pixel scale soil water content measuring method, provides a soil water content remote sensing monitoring ground verification method based on a ground penetrating radar through combining field experiments and ground penetrating radar technical means with a mathematical statistic method, breaks through the bottleneck that the ground verification relies on the traditional point scale measuring method for a long time, and expands the application and research fields; the method has the advantages of better expansibility, high measuring speed, convenience and quickness, more stable verification result than the traditional point scale measuring method, higher credibility of the verification result, reduction of verification error caused by scale problem, theoretical support and method approach for realizing reasonable verification and evaluation of soil water remote sensing products, and capability of serving application of soil water content remote sensing monitoring products in water conservancy services such as drought resistance and disaster reduction services, accurate agricultural water management, strictest water resource management and the like
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A ground penetrating radar is used for measuring soil moisture, and is characterized in that:
comprises a supporting platform (1), a transmitting antenna (2), a receiving antenna (3) and a display;
travelling wheels (11) are arranged on the supporting platform (1), so that the supporting platform (1) can move on the surface of soil to be measured through the travelling wheels (11), the transmitting antenna (2) and the receiving antenna (3) can be fixed on the supporting platform (1), and the receiving antenna (3) is electrically connected with the display;
the transmitting antenna (2) transmits electromagnetic waves, the receiving antenna (3) can receive the electromagnetic waves transmitted by the transmitting antenna (2) and transmit the wave speed of the received electromagnetic waves to the display to be displayed, and the receiving antenna (3) receives the electromagnetic waves transmitted by the transmitting antenna (2) and comprises air waves and ground direct waves.
2. The ground penetrating radar of claim 1, wherein:
the supporting platform (1) is made of plastic.
3. The ground penetrating radar of claim 1, wherein:
the device also comprises a handle (12) fixedly connected with the supporting platform (1);
the handle (12) and the travelling wheel (11) are respectively positioned at two ends of the supporting platform (1).
4. The georadar of any one of claims 1 to 3, wherein:
the device also comprises a supporting shaft (4) and a mounting rod (5);
the axis of the supporting shaft (4) is vertical to the upper surface of the supporting platform (1), one end of the supporting shaft is fixedly connected to the upper surface of the supporting platform (1), the other end of the supporting shaft is fixedly connected to the middle of the mounting rod (5), and the axis of the mounting rod (5) is vertical to the axis of the supporting shaft (4), so that the mounting rod (5) and the supporting shaft (4) form a T shape;
the edge the axis direction of installation pole (5), installation pole (5) are located the part of back shaft (4) both sides is first installation department (51) and second installation department (52) respectively, receiving antenna (3) are installed on first installation department (51), transmitting antenna (2) are installed on second installation department (52).
5. The ground penetrating radar of claim 4, wherein:
the antenna also comprises a first fixing nut (6) and a first connecting rod (7) fixedly connected with the receiving antenna (3);
a first through hole (71) is formed in the first connecting rod (7), and the first connecting rod (7) is sleeved on the first mounting part (51) through the first through hole (71);
be provided with on first installation department (51) with first fixation nut (6) assorted first screw thread, the quantity of first fixation nut (6) is two, two equal threaded connection of first fixation nut (6) is in on first installation department (51), and follow the axis direction of installation pole (5), two first fixation nut (6) are located the both sides of head rod (7), so that two first fixation nut (6) can be through the effect of screwing will head rod (7) are fixed on first installation department (51).
6. The ground penetrating radar of claim 5, wherein:
the antenna also comprises a second fixing nut (8) and a second connecting rod (9) fixedly connected with the transmitting antenna (2);
a second through hole is formed in the second connecting rod (9), and the second connecting rod (9) is sleeved on the second mounting part (52) through the second through hole;
be provided with on second installation department (52) with second fixation nut (8) assorted second screw thread, the quantity of second fixation nut (8) is two, two the equal threaded connection of second fixation nut (8) is in on second installation department (52), and follow the axis direction of installation pole (5), two second fixation nut (8) are located the both sides of second connecting rod (9), so that two second fixation nut (8) can be through the effect of screwing will second connecting rod (9) are fixed on second installation department (52).
7. A method for measuring soil moisture is characterized in that:
using a ground penetrating radar as claimed in any one of claims 1 to 6;
the method comprises the following steps:
s100, moving the ground penetrating radar and enabling the transmitting antenna to transmit electromagnetic waves
S200, the receiving antenna receives the electromagnetic wave transmitted by the transmitting antenna, transmits the wave speed information of the received electromagnetic wave to a display for displaying, and calculates the wave speed V of the electromagnetic wave according to the wave speed informationGW；
S300, according to wave velocity V of electromagnetic waveGWAnd calculating the water content theta of the soil.
Preferably, in step S300, θ ═ 0.053+ 0.0293-0.000552+0.00000433Wherein is the dielectric constant;
＝(c/VGW)2where c is the propagation velocity of the electromagnetic wave in air.
Preferably, step S100 includes: adjusting a distance x between the transmitting antenna and the receiving antenna;
in step S300, the electromagnetic waves received by the receiving antenna and transmitted by the transmitting antenna include an air wave and a ground direct wave, and the wave velocity t of the air wave is calculated according to the wave velocity information of the air wave displayed on the displayAWAnd simultaneously calculating the wave velocity t of the ground direct wave according to the wave velocity of the ground direct wave displayed on the displayGWAnd V isGW＝x/(tGW-tAW+x/c)。
Preferably, step S100 includes: and adjusting the distance x between the transmitting antenna and the receiving antenna, and fixing the transmitting antenna and the receiving antenna on the supporting platform when x reaches a reasonable value, wherein x is more than or equal to 1.2 meters and less than or equal to 1.8 meters.
Preferably, when the ground penetrating radar further comprises a support shaft, a mounting rod, a first fixing nut and a first connecting rod fixedly connected with the receiving antenna;
step S100 includes: and moving the receiving antenna along the axial direction of the mounting rod to adjust the distance x between the transmitting antenna and the receiving antenna, and when x reaches a reasonable value, fixing a first connecting rod on the mounting rod through the first fixing nut, wherein x is more than or equal to 0.38 m and less than or equal to 5 m.
Preferably, when the ground penetrating radar further comprises a support shaft, a mounting rod, a first fixing nut, a first connecting rod fixedly connected with the receiving antenna, a second fixing nut and a second connecting rod fixedly connected with the transmitting antenna;
step S100 includes: moving the receiving antenna and the transmitting antenna along the axial direction of the mounting rod to adjust the distance x between the transmitting antenna and the receiving antenna, when x reaches a reasonable value, fixing a first connecting rod on the mounting rod through the first fixing nut, and fixing a second connecting rod on the mounting rod through the second fixing nut;
in the axial direction of the mounting rod, the distance between the transmitting antenna and the axial line of the supporting shaft is equal to the distance between the receiving antenna and the axial line of the supporting shaft, wherein x is more than or equal to 0.38 m and less than or equal to 5 m.
8. The soil moisture measuring method according to claim 7, characterized in that:
the measured ground area (100) is rectangular;
in step S100, a moving path of the ground penetrating radar includes a first path (101) and a second path (102), and the first path (101) and the second path (102) are two diagonal lines of the operation.
Preferably, in step S100, the moving path of the ground penetrating radar includes at least one third path (103) located inside the rectangle, and the third path (103) is parallel to the first path (101);
and/or, in step S100, the moving path of the ground penetrating radar includes at least one fourth path (104), and the fourth path (104) is parallel to the second path (102).
9. The soil moisture measuring method according to claim 7, characterized in that:
the measured ground area (100) is a rectangle, and the rectangle comprises a first side line (107) and a second side line (108) which are perpendicular to each other;
in step S100, the moving path of the ground penetrating radar includes a fifth path (105) and a sixth path (106) located inside the rectangle, the fifth path (105) is parallel to the first edge (107), and the sixth path (106) is parallel to the second edge (108).
10. Measuring method according to claim 9, characterized in that
The number of the fifth paths (105) is at least two and/or the number of the sixth paths (106) is at least two.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010729235.XA CN111812725A (en) | 2020-07-27 | 2020-07-27 | Ground penetrating radar and soil moisture measuring method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010729235.XA CN111812725A (en) | 2020-07-27 | 2020-07-27 | Ground penetrating radar and soil moisture measuring method |
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