A method for calibrating the accuracy of a GNSS monitoring device

Abstract

The present invention discloses a method for calibrating the accuracy of GNSS monitoring equipment. The method sets a GNSS reference station in an open, unobstructed area without other receiving or transmitting equipment, sets GNSS monitoring equipment to be calibrated at positions with different spacings from the GNSS reference station, and performs accuracy calibration of the GNSS monitoring equipment to be calibrated at different spacings by adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions. Taking into account the path effect of the obstruction, the obstruction is set at a position with a set value of the spacing from the GNSS reference station, and the accuracy calibration of the GNSS monitoring equipment to be calibrated at different spacings under obstruction conditions and different obstruction times is performed, thereby achieving accuracy calibration of the GNSS monitoring equipment and providing a scientific method and basis for inspecting and verifying the applicability and accuracy of GNSS equipment.

Description

Technical Field

[0001] The present invention relates to a method for calibrating the accuracy of GNSS monitoring equipment, belonging to the field of deformation monitoring of earth-rock dams in water conservancy and hydropower projects. Background Art

[0002] An earth-rock dam is one of the three major dam types in water conservancy projects and is also the most widely used dam type. The construction technology of earth-rock dams is simple, has good performance in adapting to deformation, and has low requirements for the foundation. However, excessive deformation of earth-rock dams affects the construction and long-term safe operation of the impervious body to a certain extent. The deformation of earth-rock dams includes surface deformation and internal deformation, among which surface deformation is an intuitive factor reflecting the operation state of the dam and is also the focus of earth-rock dam deformation monitoring.

[0003] Before using GNSS equipment for the apparent deformation monitoring of earth-rock dams, it is necessary to first determine the actual monitoring accuracy of the monitoring equipment, that is, to calibrate its accuracy, clarify the applicable range of each GNSS monitoring equipment, and provide a scientific basis for the selection of earth-rock dam apparent deformation monitoring equipment. However, there is currently no corresponding calibration method. Summary of the Invention

[0004] The present invention provides a method for calibrating the accuracy of GNSS monitoring equipment, which solves the problems disclosed in the background art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for calibrating the accuracy of GNSS monitoring equipment includes:

[0007] Set up a GNSS reference station in an open, unobstructed area without other receiving or transmitting equipment;

[0008] Set up the GNSS monitoring equipment to be calibrated at positions with different distances from the GNSS reference station according to the length of the earth-rock dam axis. By adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, calibrate the accuracy of the GNSS monitoring equipment to be calibrated at different distances;

[0009] Set up an obstacle at a position with a set value from the GNSS reference station, and set up the GNSS monitoring equipment to be calibrated at positions with different distances from the obstacle. By adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, calibrate the accuracy of the GNSS monitoring equipment to be calibrated at different distances under the occlusion condition, and calibrate the accuracy of the GNSS monitoring equipment to be calibrated at different occlusion times and different distances; wherein, the obstacle blocks the horizontal line of sight between the GNSS monitoring equipment to be calibrated and the GNSS reference station.

[0010] The GNSS reference station includes a forced centering device and a GNSS antenna installed on the forced centering device.

[0011] The GNSS monitoring device to be calibrated is installed on a three-way moving platform. Through the three-way moving platform, the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions are adjusted.

[0012] According to the length of the axis of the earth-rock dam, GNSS monitoring devices to be calibrated are set at positions with different distances from the GNSS reference station. By adjusting the distances of the GNSS monitoring devices to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring devices to be calibrated at different distances is carried out, including:

[0013] According to the length of the axis of the earth-rock dam, GNSS monitoring devices to be calibrated are set at positions with different distances from the GNSS reference station;

[0014] For each GNSS monitoring device to be calibrated at different distances, by adjusting the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring device to be calibrated is carried out.

[0015] An obstacle is set at a position with a set value of the distance from the GNSS reference station, and GNSS monitoring devices to be calibrated are set at positions with different distances from the obstacle. By adjusting the distances of the GNSS monitoring devices to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring devices to be calibrated at different distances under the occlusion condition is carried out, and the accuracy calibration of the GNSS monitoring devices to be calibrated at different occlusion times and different distances is carried out, including:

[0016] An obstacle is set at a position with a set value of the distance from the GNSS reference station, and GNSS monitoring devices to be calibrated are set at positions with different distances from the obstacle;

[0017] Under the occlusion condition, for each GNSS monitoring device to be calibrated at different distances, by adjusting the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring device to be calibrated is carried out;

[0018] Under the occlusion condition, for each GNSS monitoring device to be calibrated at different distances, by adjusting the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring device to be calibrated under different occlusion durations is carried out.

[0019] For each GNSS monitoring device to be calibrated at different distances, by adjusting the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring device to be calibrated is carried out, including:

[0020] For a GNSS monitoring device to be calibrated at a certain distance, start the GNSS reference station and the GNSS monitoring device to be calibrated, and let it stand for a preset duration A;

[0021] For each adjustment direction, adjust the GNSS monitoring device to be calibrated by a preset distance in the adjustment direction, monitor the monitoring data in the adjustment direction after a predicted time A, calculate the average value of all monitoring data. If the deviation between the average value and the corresponding adjustment distance does not exceed the threshold, adjust the next preset distance in the adjustment direction and re-judge the deviation until the deviation exceeds the threshold. The minimum adjustment distance corresponding to the deviation that does not exceed the threshold is the accuracy of the GNSS monitoring device to be calibrated in the adjustment direction. Among them, the adjustment directions include the horizontal direction and the vertical direction. In one adjustment direction, the adjustment distance for the next time is less than that for the previous time.

[0022] Under the occlusion condition, for the GNSS monitoring devices to be calibrated with different spacings, calibrate the accuracy of the GNSS monitoring devices to be calibrated under different occlusion durations by adjusting the distances of the GNSS monitoring devices to be calibrated in the horizontal and vertical directions, including:

[0023] Under the occlusion condition, for the GNSS monitoring device to be calibrated with a certain spacing, start the GNSS reference station and the GNSS monitoring device to be calibrated, and statically wait for a preset duration A.

[0024] Traverse all preset occlusion durations. For each adjustment direction, adjust the GNSS monitoring device to be calibrated by a preset distance in the adjustment direction, monitor for a preset occlusion duration A1, then remove the occluder, and continue to monitor for A - A1 to obtain the monitoring data before removing the occluder and the monitoring data after removing the occluder in the adjustment direction. Calculate the average value of all monitoring data. If the deviation between the average value and the corresponding adjustment distance does not exceed the threshold, adjust the next preset distance in the adjustment direction and re-judge the deviation until the deviation exceeds the threshold. The minimum adjustment distance corresponding to the deviation that does not exceed the threshold is the accuracy of the GNSS monitoring device to be calibrated under the current occlusion duration and adjustment direction. Among them, the adjustment directions include the horizontal direction and the vertical direction. In one adjustment direction, the adjustment distance for the next time is less than that for the previous time.

[0025] The horizontal direction includes the X-axis direction and the Y-axis direction. There are N adjustment distances in the vertical direction, N / 2 adjustment distances in the X-axis direction of the horizontal direction, and N / 2 adjustment distances in the Y-axis direction of the horizontal direction.

[0026] Advantages achieved by the present invention: The present invention sets up a GNSS reference station in a site that is open, unobstructed, and has no other receiving or transmitting equipment. It sets up GNSS monitoring equipment to be calibrated at positions with different distances from the GNSS reference station. By adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances is carried out. Considering the path effect of the obstruction, an obstruction is set at a position with a set value of the distance from the GNSS reference station, and the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances under the obstruction condition is carried out, and the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances with different obstruction times is carried out, thereby realizing the accuracy calibration of the GNSS monitoring equipment and providing a scientific method and basis for testing and verifying the applicability and accuracy of the GNSS equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flowchart of the method of the present invention;

[0028] Figure 2 is a design drawing of a three-way moving platform;

[0029] Figure 3 is a layout and structure schematic diagram of the reference station and the monitoring station. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0031] As Figure 1 shown, a method for calibrating the accuracy of GNSS monitoring equipment includes the following steps:

[0032] Step 1, set up a GNSS reference station in a site that is open, unobstructed, and has no other receiving or transmitting equipment;

[0033] Step 2, according to the length of the axis of the earth-rock dam, set up GNSS monitoring equipment to be calibrated at positions with different distances from the GNSS reference station, and carry out the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances by adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions;

[0034] Step 3, set up an obstruction at a position with a set value of the distance from the GNSS reference station, set up GNSS monitoring equipment to be calibrated at positions with different distances from the obstruction, and carry out the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances under the obstruction condition by adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, and carry out the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances with different obstruction times; wherein, the obstruction blocks the horizontal line of sight between the GNSS monitoring equipment to be calibrated and the GNSS reference station.

[0035] The above method sets up a GNSS reference station in a site that is open, unobstructed, and has no other receiving or transmitting equipment. GNSS monitoring equipment to be calibrated is set at positions with different distances from the GNSS reference station. By adjusting the horizontal and vertical distances of the GNSS monitoring equipment to be calibrated, the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances is carried out. Considering the path effect of obstacles, obstacles are set at positions with a set value of the distance from the GNSS reference station, and the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances under the occlusion condition is carried out. The accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances under different occlusion times is carried out, thereby realizing the accuracy calibration of the GNSS monitoring equipment, and providing a scientific method and basis for testing and verifying the applicability and accuracy of GNSS equipment.

[0036] GNSS measures the distance between known satellites and the user receiver, and solves the specific position of the receiver by integrating data from multiple satellites. The GNSS monitoring accuracy is affected not only by receiving equipment and calculation software, but also by environmental factors. Especially when applied to water conservancy projects, since water conservancy projects are generally built in mountainous and canyon areas, blocked by mountains, stones, and trees, with complex and changeable climates, and affected by strong reflection areas such as rivers and lakes, the monitoring accuracy of GNSS monitoring equipment is lower than its theoretical value. In addition, during the construction period of the dam, due to the existence of temporary obstacles such as vehicles, the measurement accuracy of GNSS monitoring equipment is affected to a certain extent. Therefore, it is necessary to carry out accuracy calibration under different distances, different occlusion conditions at different distances, and different occlusion times at different distances.

[0037] During calibration, first, the test site needs to be selected. A site that is open, unobstructed (i.e., without obstacles such as high-rise buildings and big trees), and has no other receiving or transmitting equipment can be selected. Further, observation piles are placed in the selected site. The observation pile is a platform made of concrete casting, and the designed size of the platform is 40 cm × 40 cm × 100 cm (length × width × height). A GNSS reference station is installed on the top of the observation pile. The GNSS reference station includes a forced centering device and a GNSS antenna installed on the forced centering device. The forced centering device is buried on the top of the platform and is used to fix the GNSS antenna.

[0038] According to the requirements of the deformation monitoring accuracy of earth-rock dams, make Figure 2The three-way moving platform shown, that is, a pan-tilt platform that moves precisely along the X, Y, and Z directions. The size of the tabletop of the three-way moving platform is 20 cm × 20 cm, with a load capacity of 15 kg. Screw holes are reserved at both the top and bottom of the platform. According to the specification requirements: the horizontal and vertical monitoring accuracies of the earth-rock dam are not less than ±2 mm. To calibrate the accuracy of the GNSS monitoring equipment, the minimum scale for the platform to move horizontally and vertically is set to 0.01 mm; according to the determined minimum scale, micrometer handles are set in the X, Y, and Z directions respectively. When the handle rotates one week, the platform moves 0.5 mm in that direction. The maximum stroke in the three directions of the platform is set to 3 cm; this three-way moving platform is a relatively common platform, and its specific structure will not be described in detail here.

[0039] The GNSS monitoring equipment to be calibrated is installed on the above-mentioned three-way moving platform. Through the three-way moving platform, the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions are adjusted. As Figure 3 shown, the three-way moving platform is installed on a movable and fixable observation pile through a forced centering device. All connection parts are ensured to be firmly connected, and the forced centering device and the top plane of the moving platform are kept horizontal to ensure that the monitoring equipment does not move or tilt under adverse weather conditions such as strong winds, rain, and snow.

[0040] According to the length of the dam axis of the earth-rock dam, the GNSS monitoring equipment to be calibrated is fixed at positions with different distances from the GNSS reference station. By adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring equipment to be calibrated at different distances is carried out. The specific process is as follows:

[0041] 1) According to the length of the dam axis of the earth-rock dam, the GNSS monitoring equipment to be calibrated is set at positions with different distances from the GNSS reference station.

[0042] 2) For the GNSS monitoring equipment to be calibrated at each distance, by adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring equipment to be calibrated is carried out.

[0043] For the GNSS monitoring equipment to be calibrated at each distance, by adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring equipment to be calibrated is carried out, including:

[0044] 21) For the GNSS monitoring equipment to be calibrated at a certain distance, start the GNSS reference station and the GNSS monitoring equipment to be calibrated, and let it stand for a preset duration A. The preset duration A is generally 24 hours;

[0045] 22) For each adjustment direction, adjust the GNSS monitoring device to be calibrated by a preset distance in the adjustment direction, monitor the monitoring data in the adjustment direction after a predicted monitoring time A, calculate the average value of all the monitoring data. If the deviation between the average value and the corresponding adjustment distance does not exceed the threshold (the threshold is 20%), adjust the preset next distance in the adjustment direction and re-judge the deviation until the deviation exceeds the threshold. The minimum adjustment distance corresponding to the deviation that does not exceed the threshold is the accuracy of the GNSS monitoring device to be calibrated in the adjustment direction. Among them, the adjustment directions include the horizontal direction and the vertical direction. In one adjustment direction, the adjustment distance for the latter time is less than that for the previous time, and the deviation = abs(average value - adjustment distance) / adjustment distance.

[0046] When calibrating with different spacings, after moving the observation stake installed with the GNSS monitoring device to be calibrated to the monitoring point, fix it to the ground, level it by leveling. Rotate the handle of the three-way moving platform so that the three directions of the three-way moving platform reach the maximum stroke, tighten the fixing bolts, start the GNSS reference station and the GNSS monitoring device to be calibrated. After standing for 24 hours, perform accuracy calibration. The moving distances of the three-way moving platform in the horizontal and vertical directions are 2 cm, 1 cm, 0.5 cm, 0.4 cm, 0.3 cm, 0.2 cm, 0.1 cm, and 0.05 cm respectively. Monitor for 24 hours after each movement, calculate the average value of the monitoring data, and compare it with the moving distance. When the deviation between the monitored value and the moving value exceeds 20%, it is considered that the moving distance of the platform has exceeded the monitoring accuracy of the GNSS device.

[0047] The three-way moving platform can move in two mutually perpendicular directions on the horizontal plane and vertically. The three directions are independent and will not interfere with each other, that is, they can be adjusted separately or simultaneously. The accuracy calibration of the GNSS device, simply put, is to determine how much the smallest deformation it can monitor under the engineering environmental background conditions. By artificially giving an adjustment distance and then using the GNSS device to monitor, see how much the monitored quantity differs from the given adjustment distance. If it is less than the error limit, it is considered that the deformation amount it can monitor ≤ the given adjustment distance. Finally, determine the accuracy of the GNSS device by continuously reducing the adjustment distance.

[0048] The horizontal direction includes the X-axis direction and the Y-axis direction. Assuming there are N adjustment distances in the vertical direction, then there are N / 2 adjustment distances in the X-axis direction of the horizontal direction and N / 2 adjustment distances in the Y-axis direction of the horizontal direction. See Table 1 for details.

[0049] Table 1 Adjustment Direction and Distance Table

[0050]

[0051]

[0052] The horizontal direction accuracy of the GNSS positioning device is consistent, but it is inconsistent with the deformation accuracy in the vertical direction. Therefore, during actual testing, a displacement is given in the horizontal direction and another displacement is given in the vertical direction. In the present invention, displacements in two directions, X and Y, are given in the horizontal direction, which can accelerate the testing progress. A deformation of 2 cm is given in the X direction and a deformation of 1 cm is given in the Y direction. They both belong to the horizontal direction accuracy, so the monitoring quantity in the horizontal direction can be reduced by half.

[0053] Considering the influence of the temporarily moving device, an obstacle is set at a position with a distance from the GNSS reference station equal to the set value, where the set value is 50 m. It is required that the obstacle is about 5 m higher than the top of the GNSS monitoring device, completely blocking the horizontal line of sight between the GNSS monitoring device and the GNSS reference station. The GNSS monitoring device to be calibrated is set at positions with different distances from the obstacle. By adjusting the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring device to be calibrated at different distances under the occlusion condition is carried out, and the accuracy calibration of the GNSS monitoring device to be calibrated at different occlusion times and different distances is carried out. The specific process is as follows:

[0054] A1) Set an obstacle at a position 50 m away from the GNSS reference station, and set the GNSS monitoring device to be calibrated at positions with different distances from the obstacle.

[0055] A2) Under the occlusion condition, for the GNSS monitoring device to be calibrated at each distance, by adjusting the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring device to be calibrated is carried out; the process of this step is the same as that of 21) - 22), and will not be described repeatedly here.

[0056] A3) Under the occlusion condition, for the GNSS monitoring device to be calibrated at each distance, by adjusting the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring device to be calibrated under different occlusion durations is carried out; it includes:

[0057] A31) Under the occlusion condition, for the GNSS monitoring device to be calibrated at a certain distance, start the GNSS reference station and the GNSS monitoring device to be calibrated, and let them stand for a preset duration A;

[0058] A32) Traverse all preset occlusion durations. For each adjustment direction, adjust the GNSS monitoring device to be calibrated by a preset distance in the adjustment direction. After monitoring for the preset occlusion duration A1, remove the occluder, continue monitoring for A - A1, and obtain the monitoring data before removing the occluder and the monitoring data after removing the occluder in the adjustment direction. Calculate the average value of all monitoring data. If the deviation between the average value and the corresponding adjustment distance does not exceed the threshold, adjust the next preset distance in the adjustment direction and re - judge the deviation until the deviation exceeds the threshold. The minimum adjustment distance corresponding to the deviation that does not exceed the threshold is the accuracy of the GNSS monitoring device to be calibrated under the current occlusion duration and adjustment direction. Among them, the adjustment directions include the horizontal direction and the vertical direction. In one adjustment direction, the adjustment distance of the latter time is less than that of the previous time.

[0059] Furthermore, under the condition of the same spacing, the monitoring data of the GNSS device to be calibrated with and without occlusion can be calculated, and the difference between the average data of the two (that is, the difference between the average data under the condition of no occlusion and the condition of right occlusion under the same spacing) can be calculated to obtain the influence amount of the path effect considering the occluder on the monitoring result.

[0060] For the monitoring under the above - mentioned occlusion conditions, monitoring points can be demarcated at positions 5m, 10m, and 50m away from the occluder. The monitoring points and the reference station are located on both sides of the occluder respectively. Move the monitoring steel frame 3 to the monitoring points. After leveling the level, according to the monitoring scheme with different spacings, gradually reduce the adjustment distance to determine the monitoring accuracy of the GNSS monitoring device under the occlusion conditions. Considering the influence of different occlusion durations on the monitoring accuracy, remove the occluder when the monitoring time is 2h, 6h, 8h, 12h, and 18h respectively, and complete the monitoring for the remaining time. Take the average value of the monitoring data during the entire monitoring period and compare it with the moving distance respectively to further determine the influence of different occlusion times on the GNSS monitoring accuracy.

[0061] With high - precision positioning technology as the core, the present invention proposes a method for calibrating the accuracy of the GNSS monitoring device for earth - rock dam deformation, clarifies the actual monitoring accuracy of the GNSS monitoring device under actual engineering conditions, and provides a scientific method and basis for testing and verifying the applicability and accuracy of the GNSS device.

[0062] The above - mentioned is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A method for calibrating the accuracy of a GNSS monitoring device, characterized in that, Including: Set up a GNSS reference station in an open, unobstructed area without other receiving or transmitting devices; According to the length of the earth-rock dam axis, set up the GNSS monitoring equipment to be calibrated at positions with different distances from the GNSS reference station. By adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, calibrate the accuracy of the GNSS monitoring equipment to be calibrated at different distances; Set up an obstruction at a position with a set value of the distance from the GNSS reference station, and set up the GNSS monitoring equipment to be calibrated at positions with different distances from the obstruction. By adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, calibrate the accuracy of the GNSS monitoring equipment to be calibrated at different distances under the obstruction condition, and calibrate the accuracy of the GNSS monitoring equipment to be calibrated at different obstruction times and different distances; wherein, the obstruction blocks the horizontal line of sight between the GNSS monitoring equipment to be calibrated and the GNSS reference station; For the GNSS monitoring equipment to be calibrated at each distance, by adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, calibrate the accuracy of the GNSS monitoring equipment to be calibrated, including: For the GNSS monitoring equipment to be calibrated at a certain distance, start the GNSS reference station and the GNSS monitoring equipment to be calibrated, and let it stand for a preset duration A; for each adjustment direction, adjust the GNSS monitoring equipment to be calibrated by a preset distance in the adjustment direction, monitor the monitoring data in the adjustment direction after a prediction time A, calculate the average value of all monitoring data. If the deviation between the average value and the corresponding adjustment distance does not exceed the threshold, adjust the next preset distance in the adjustment direction and re-judge the deviation until the deviation exceeds the threshold. The minimum adjustment distance corresponding to the deviation that does not exceed the threshold is the accuracy of the GNSS monitoring equipment to be calibrated in the adjustment direction; wherein, the adjustment directions include the horizontal direction and the vertical direction, and in one adjustment direction, the adjustment distance of the latter time is less than that of the previous time; Under the obstruction condition, for the GNSS monitoring equipment to be calibrated at each distance, by adjusting the distances of the GNSS monitoring equipment to be calibrated in the horizontal and vertical directions, calibrate the accuracy of the GNSS monitoring equipment to be calibrated under different obstruction durations, including: Under the obstruction condition, for the GNSS monitoring equipment to be calibrated at a certain distance, start the GNSS reference station and the GNSS monitoring equipment to be calibrated, and let it stand for a preset duration A; traverse all preset obstruction durations. For each adjustment direction, adjust the GNSS monitoring equipment to be calibrated by a preset distance in the adjustment direction, monitor for a preset obstruction duration A1, then remove the obstruction, and continue to monitor for A - A1 to obtain the monitoring data before removing the obstruction and the monitoring data after removing the obstruction in the adjustment direction. Calculate the average value of all monitoring data. If the deviation between the average value and the corresponding adjustment distance does not exceed the threshold, adjust the next preset distance in the adjustment direction and re-judge the deviation until the deviation exceeds the threshold. The minimum adjustment distance corresponding to the deviation that does not exceed the threshold is the accuracy of the GNSS monitoring equipment to be calibrated under the current obstruction duration and adjustment direction.

2. A method for calibrating the accuracy of a GNSS monitoring device according to claim 1, characterized in that The GNSS reference station includes a forced centering device and a GNSS antenna mounted on the forced centering device.

3. A method for calibrating the accuracy of a GNSS monitoring device according to claim 1, characterized in that, The GNSS monitoring device to be calibrated is installed on a three-way moving platform. Through the three-way moving platform, the distances of the GNSS monitoring device to be calibrated in the horizontal and vertical directions are adjusted.

4. A method for calibrating the accuracy of a GNSS monitoring device according to claim 1, characterized in that, According to the length of the earth-rock dam axis, the GNSS monitoring devices to be calibrated are set at positions with different distances from the GNSS reference station. By adjusting the distances of the GNSS monitoring devices to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring devices to be calibrated at different distances is carried out, including: According to the length of the earth-rock dam axis, the GNSS monitoring devices to be calibrated are placed at positions with different distances from the GNSS reference station; For the GNSS monitoring devices to be calibrated at each distance, by adjusting the distances of the GNSS monitoring devices to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring devices to be calibrated is carried out.

5. A method for calibrating the accuracy of a GNSS monitoring device according to claim 1, characterized in that, An obstacle is set at a position with a set value of the distance from the GNSS reference station, and the GNSS monitoring devices to be calibrated are set at positions with different distances from the obstacle. By adjusting the distances of the GNSS monitoring devices to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring devices to be calibrated at different distances under the obstacle condition is carried out, and the accuracy calibration of the GNSS monitoring devices to be calibrated at different distances and different occlusion times is carried out, including: An obstacle is set at a position with a set value of the distance from the GNSS reference station, and the GNSS monitoring devices to be calibrated are set at positions with different distances from the obstacle; Under the obstacle condition, for the GNSS monitoring devices to be calibrated at each distance, by adjusting the distances of the GNSS monitoring devices to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring devices to be calibrated is carried out; Under the obstacle condition, for the GNSS monitoring devices to be calibrated at each distance, by adjusting the distances of the GNSS monitoring devices to be calibrated in the horizontal and vertical directions, the accuracy calibration of the GNSS monitoring devices to be calibrated under different occlusion durations is carried out.

6. A method for calibrating the accuracy of a GNSS monitoring device according to claim 1, characterized in that, The horizontal direction includes the X-axis direction and the Y-axis direction. There are N adjustable distances in the vertical direction, N / 2 adjustable distances in the X-axis direction of the horizontal direction, and N / 2 adjustable distances in the Y-axis direction of the horizontal direction.

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