Measurement method, system and RTK receiver for GNSS

Abstract

The present invention discloses a measurement method, system and RTK receiver for GNSS. The measurement system includes a base station and a mobile station. The mobile station includes a built-in memory, an RTK solution engine and a PPK solution engine. The measurement method includes: the mobile station receives the base station signal and the GNSS signal of the base station at the measurement point; obtains the RTK solution result through the RTK solution engine, and stores the base station signal and the GNSS signal in the built-in memory in time sequence; determines whether the RTK solution result meets the preset conditions, if not, calls the PPK solution engine to perform PPK solution at the measurement point to obtain the PPK solution result; the mobile station obtains the positioning information of the measurement point according to the RTK solution result and the PPK solution result. The present invention can improve the reliability of the measurement point result, improve the fixation rate of the measurement result, and save data collection time and internal work time.

Description

Technical Field

[0001] The invention relates to a measurement method and system for GNSS and an RTK receiver. Background Art

[0002] Satellite navigation and positioning technology has basically replaced ground-based radio navigation, traditional geodetic and astronomical measurement navigation and positioning technology, and has promoted new developments in the fields of geodetic measurement and navigation and positioning. Today, the GNSS system is not only the infrastructure of national security and economy, but also an important symbol of the status of a modern great power and the country's comprehensive national strength. Due to its important significance in politics, economy, and military, the world's major military powers and economies are competing to develop independent satellite navigation systems.

[0003] GNSS (Global Navigation Satellite System) refers to the world's four major navigation and positioning systems, including the United States' GPS, Russia's GLONASS, Europe's Galileo, and my country's Beidou. It can provide users with uninterrupted, high-precision navigation signal resources with global coverage, thereby realizing all-weather real-time positioning, speed measurement and timing functions.

[0004] At present, the real-time kinematic measurement (RTK) technology of the global positioning system has been widely used to implement plane control measurement, elevation control measurement, terrain measurement, etc. However, in high-precision measurement operations, poor observation conditions such as dense forests and urban canyons may be encountered, making it impossible for RTK to obtain a fixed solution, and there may also be fixed errors. If it cannot be fixed, dynamic post-processing (PPK) technology is generally used, which requires more than 15 minutes of data collection at the measurement point, and there is no guarantee that a fixed result can be obtained. If the fixation error is found during the internal operation, the surveyor needs to re-measure. Both situations affect the efficiency of the measurement operation. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art GNSS-based measurement technology being limited by the receiving environment, resulting in poor observation effect and low work efficiency, and to provide a measurement method, system and RTK receiver for GNSS that can improve the reliability of measurement point results, improve the fixation rate of measurement results, and save data collection time and office work time.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] A measurement method for GNSS, used in a measurement system, wherein the measurement system includes a base station and at least one mobile station, wherein the mobile station includes a built-in memory, an RTK solution engine and a PPK solution engine, and the measurement method includes:

[0008] The mobile station receives a base station signal and a GNSS signal of a reference station at a measurement point;

[0009] The base station signal and the GNSS signal are solved by the RTK solution engine to obtain the RTK solution result, and the base station signal and the GNSS signal are stored in the built-in memory in a time sequence;

[0010] Determine whether the RTK solution result meets the preset conditions, and if not, call the PPK solution engine to perform PPK solution at the measurement point to obtain the PPK solution result;

[0011] The mobile station obtains the positioning information of the measuring point according to the RTK solution result and the PPK solution result.

[0012] Preferably, the determining whether the RTK solution result meets a preset condition includes:

[0013] It is determined whether the RTK solution result meets the preset conditions. If so, the mobile station obtains the positioning information of the measurement point according to the RTK solution result.

[0014] Preferably, the calling of the PPK solution engine to perform PPK solution at the measurement point to obtain a PPK solution result includes:

[0015] Calling the PPK solution engine to perform PPK solution at the measurement point according to a preset starting point to obtain a starting point solution result;

[0016] Calculate the solution results of all the starting points of the measurement points according to the preset rules;

[0017] The PPK solution result of the measuring point and the reliability of the PPK solution result are obtained according to the solution results of all the starting points of the measuring point and the fixed results in the solution results.

[0018] Preferably, the mobile station obtains the positioning information of the measuring point according to the RTK solution result and the PPK solution result, including:

[0019] The mobile station verifies the RTK solution result according to the PPK solution result of the measurement point, and obtains weighted positioning information of the RTK solution result and the PPK solution result according to the verification result, wherein the higher the reliability of the solution result, the higher the weight of the solution result in the weighted positioning information.

[0020] Preferably, the duration between adjacent starting points is a fixed value, and the preset rules include:

[0021] The mobile station performs PPK solution from the starting point in time sequence to obtain the PPK solution result of each starting point; and / or,

[0022] The mobile station performs PPK solution from a starting point in reverse time sequence to obtain a PPK solution result for each starting point.

[0023] Preferably, the obtaining of the PPK solution result of the measuring point and the reliability of the PPK solution result according to the solution results of all the starting points of the measuring point and the fixed results in the solution results includes:

[0024] Using the starting points known as fixed results on the measuring point, the solution results of the starting points on the measuring point other than the starting points of the fixed results are inferred to obtain all the starting points on the measuring point that are fixed results;

[0025] The PPK solution result of the measuring point and the reliability of the PPK solution result are obtained according to the number of fixed results.

[0026] Preferably, the calling of the PPK solution engine to perform PPK solution at the measurement point to obtain a PPK solution result includes:

[0027] Calling the PPK solution engine to perform PPK solution at the measurement point to obtain a starting point for the first fixed result;

[0028] Taking the starting point of the first fixed result as the starting point, reversely calculate the PPK solution results of the adjacent starting points in turn until the continuous starting points of all fixed results in the reverse calculation process are obtained, and the built-in memory stores the base station signal and GNSS signal of the next starting point;

[0029] Taking the starting point of the first fixed result as the starting point, the PPK solution results of the adjacent starting points are forwardly calculated in sequence until a preset number of starting points of the fixed results are obtained;

[0030] The PPK solution result of the measuring point is obtained based on the solution results of all the starting points with fixed results.

[0031] Preferably, the method of taking the first fixed result starting point as the starting point and sequentially forward calculating the PPK solution results of adjacent starting points until obtaining a preset number of fixed result starting points includes:

[0032] Taking the starting point of the first fixed result as the starting point, forwardly calculate the PPK solution results of the adjacent starting points, and determine whether the PPK solution result of the starting point is a fixed result. If not, take the starting point of the next fixed result of the starting point of the first fixed result as the starting point of the first fixed result, and reversely calculate the PPK solution results of the adjacent starting points again until the continuous starting points of all fixed results in the reverse calculation process are obtained. At the same time, the built-in memory stores the base station signal and GNSS signal of the next starting point.

[0033] Preferably, the measuring method comprises:

[0034] The user configures the relevant parameters of the mobile station's quasi-real-time PPK solution engine through commands, wherein the relevant parameters include the start time, filtering direction and number of calculations; and / or,

[0035] The base station signal and GNSS signal in the built-in memory are transmitted to the host computer, and the host computer uses the base station signal and GNSS signal to perform PPK solution to obtain the positioning information of all measurement points.

[0036] The present invention also provides a measurement system for GNSS, wherein the measurement system is used to implement the measurement method described above, and the measurement system includes a reference station and at least one mobile station.

[0037] The present invention also provides an RTK receiver, which is used for a reference station and / or a mobile station in the measurement system as described above.

[0038] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0039] The positive and progressive effects of the present invention are:

[0040] The present invention can improve the reliability of measurement point results, improve the fixation rate of measurement results, and save data collection time and office work time. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the structure of the measurement system of Example 1 of the present invention.

[0042] Figure 2 This is a flow chart of the measurement method of Example 1 of the present invention.

[0043] Figure 3 This is another flow chart of the measurement method of Example 1 of the present invention. DETAILED DESCRIPTION

[0044] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0045] Example 1

[0046] See also Figure 1 This embodiment provides a measurement system, which includes a plurality of RTK receivers. One of the RTK receivers is used as a base station 1, and at least one of the RTK receivers is used as a mobile station 2.

[0047] The base station 1 and the mobile station 2 each include a built-in memory 21 , the mobile station 2 includes an RTK solution engine 22 and a PPK solution engine 23 , and the RTK receiver includes a receiving module 24 and a processing module 25 .

[0048] In this embodiment, since both the base station and the mobile station are RTK receivers, the mobile station and the base station both include a receiving module, a processing module, an RTK solution engine, and a PPK solution engine.

[0049] The receiving module of the mobile station is used to receive the base station signal and the GNSS signal of the reference station at the measuring point.

[0050] The RTK solution engine of the mobile station is used to solve the base station signal and the GNSS signal to obtain the RTK solution result.

[0051] The receiving module is also used to store the base station signal and the GNSS signal in the built-in memory in a time sequence.

[0052] The processing module of the mobile station is used to determine whether the RTK solution result meets the preset conditions, and if not, call the PPK solution engine to perform PPK solution at the measurement point to obtain the PPK solution result;

[0053] Judging whether the RTK solution result meets the preset conditions refers to judging whether the RTK solution result is a fixed result and the reliability of the fixed result. If the RTK solution result is not a fixed value, or the reliability of the fixed value is low, the preset conditions are not met and the PPK solution engine is enabled.

[0054] The processing module of the mobile station is also used to obtain the positioning information of the measurement point according to the RTK solution result and the PPK solution result.

[0055] The mobile station further comprises an output module 26 for outputting positioning information.

[0056] The built-in memory of the receiver board of this embodiment can record the observation information of the board and the base station in real time. During the RTK measurement, different starting times and filtering directions can be configured through commands to perform quasi-real-time PPK.

[0057] When RTK cannot obtain fixed results or the surveyor has doubts about the measurement results, quasi-real-time PPK performs multi-starting point and multi-directional filtering, with two engines working simultaneously.

[0058] The results of quasi-PPK and RTK can be verified against each other. In addition, since the built-in memory of the board retains all observation data, PPK operations can also be performed on the PC after the field measurement is completed.

[0059] Specifically, the processing module is used to determine whether the RTK solution result meets the preset conditions. If so, the mobile station obtains the positioning information of the measurement point according to the RTK solution result. Otherwise, the PPK solution engine is called to perform PPK solution at the measurement point to obtain the PPK solution result.

[0060] Furthermore, the processing module is used for:

[0061] Calling the PPK solution engine to perform PPK solution at the measurement point according to a preset starting point to obtain a starting point solution result;

[0062] Calculate the solution results of all the starting points of the measurement points according to the preset rules;

[0063] The PPK solution result of the measuring point and the reliability of the PPK solution result are obtained according to the solution results of all the starting points of the measuring point and the fixed results in the solution results.

[0064] Furthermore, the processing module is used for:

[0065] The mobile station verifies the RTK solution result according to the PPK solution result of the measurement point, and obtains weighted positioning information of the RTK solution result and the PPK solution result according to the verification result, wherein the higher the reliability of the solution result, the higher the weight of the solution result in the weighted positioning information.

[0066] The duration between adjacent starting points is a fixed value, and the preset rules include:

[0067] The mobile station performs PPK solution from the starting point in time sequence to obtain the PPK solution result of each starting point;

[0068] The mobile station performs PPK solution from a starting point in reverse time sequence to obtain a PPK solution result for each starting point.

[0069] Furthermore, the processing module is used for:

[0070] Using the starting points known as fixed results on the measuring point, the solution results of the starting points on the measuring point other than the starting points of the fixed results are inferred to obtain all the starting points on the measuring point that are fixed results;

[0071] The PPK solution result of the measuring point and the reliability of the PPK solution result are obtained according to the number of fixed results.

[0072] This embodiment is implemented in the embedded software code of the high-precision board. While the RTK engine of the board performs real-time RTK solution, the observation data of the board and the observation data received from the base station are stored in the built-in memory of the board in time sequence. The quasi-real-time PPK engine accesses the data in the built-in memory, sets different starting points, and aligns the observation data of the board and the base station as much as possible to reduce the impact of differential delay on positioning accuracy.

[0073] Due to the full storage of data, the quasi-real-time PPK engine performs reverse filtering (solution) after measuring at the measurement point for a period of time. The multiple filtering results and RTK results are checked against each other, and finally a weighted positioning result is given.

[0074] The specific operations are as follows:

[0075] The user sets the PPK solution, sets the starting interval to 4 minutes, and the calculation direction to bidirectional filtering.

[0076] At a measurement point, if no RTK fixed solution is obtained from 10:00 to 10:05, or the fixed solution is unreliable (the output results are inconsistent several times), PPK solution is started, and the user waits at the measurement point for 15 minutes (the specific time can be adjusted according to the needs of static data) or until PPK calculates a reliable positioning result.

[0077] The forward calculation includes:

[0078] a. From 10:02 to 10:xx, output PPK result XYZ1;

[0079] b. 10:06 to 10:xx, output PPK result XYZ2;

[0080] c. 10:10 to 10:xx, output PPK result XYZ3;

[0081] The reverse calculation includes:

[0082] d. 10:02 to 10:00, output PPK result XYZ4;

[0083] e. 10:06 to 10:00, output PPK result XYZ5;

[0084] f. 10:10 to 10:00, output PPK result XYZ6;

[0085] Among the 6 positioning results, the positioning results of the fixed results are compared for consistency, and the PPK results are output.

[0086] In addition, when process a cannot obtain a fixed result, but process b can obtain a fixed result, the result of process a is inferred based on the fixed result of process b. If the result of process a is correct, the number of fixed results is increased, and the PPK solution of the measurement point is more reliable.

[0087] In other implementations, in order to obtain the PPK solution result, the processing module is used to:

[0088] Calling the PPK solution engine to perform PPK solution at the measurement point to obtain a starting point for the first fixed result;

[0089] Taking the starting point of the first fixed result as the starting point, reversely calculate the PPK solution results of the adjacent starting points in turn until the continuous starting points of all fixed results in the reverse calculation process are obtained, and the built-in memory stores the base station signal and GNSS signal of the next starting point;

[0090] Then, starting from the first fixed result starting point, the PPK solution results of the adjacent starting points are forwardly calculated in sequence until a preset number of fixed result starting points are obtained;

[0091] The PPK solution result of the measuring point is obtained based on the solution results of all the starting points with fixed results.

[0092] The above steps can save computing power and improve the efficiency of PPK solution.

[0093] Furthermore, the processing module is used for:

[0094] Taking the starting point of the first fixed result as the starting point, forwardly calculate the PPK solution results of the adjacent starting points, and determine whether the PPK solution result of the starting point is a fixed result. If not, take the starting point of the next fixed result of the starting point of the first fixed result as the starting point of the first fixed result, and reversely calculate the PPK solution results of the adjacent starting points again until the continuous starting points of all fixed results in the reverse calculation process are obtained. At the same time, the built-in memory stores the base station signal and GNSS signal of the next starting point.

[0095] Furthermore, the RTK receiver also includes a configuration module, which is used to:

[0096] The user configures the relevant parameters of the mobile station's quasi-real-time PPK solution engine through commands, and the relevant parameters include the starting time, filtering direction and number of calculations.

[0097] The RTK receiver also includes a transmission module, which is used to:

[0098] The base station signal and GNSS signal in the built-in memory are transmitted to the host computer, and the host computer uses the base station signal and GNSS signal to perform PPK solution to obtain the positioning information of all measurement points.

[0099] See also Figure 2 , using the above measurement system, this embodiment also provides a measurement method, including:

[0100] Step 100: The mobile station receives a base station signal and a GNSS signal from a reference station at a measurement point;

[0101] Step 101: Calculate the base station signal and the GNSS signal by using the RTK calculation engine to obtain the RTK calculation result, and store the base station signal and the GNSS signal in the built-in memory in time sequence;

[0102] Step 102, determine whether the RTK solution result meets the preset conditions, if yes, execute step 103, if not, execute step 104;

[0103] Step 103, the mobile station obtains the positioning information of the measuring point according to the RTK solution result, and then executes step 105;

[0104] Step 104, calling the PPK solution engine to perform PPK solution at the measurement point to obtain a PPK solution result;

[0105] Step 105: The mobile station obtains the positioning information of the measurement point according to the RTK solution result and the PPK solution result.

[0106] When the RTK solution result can obtain a fixed result, the mobile station obtains the positioning information of the measuring point according to the RTK solution result.

[0107] See also Figure 3 Specifically, step 104 includes:

[0108] Step 1041, calling the PPK solution engine to perform PPK solution at the measurement point according to a preset starting point to obtain a starting point solution result;

[0109] In this embodiment, the preset starting point refers to the moment when the calculation starts according to the preset time interval.

[0110] Step 1042, calculating the solution results of all the starting points of the measurement points according to the preset rules;

[0111] Step 1043: Obtain the PPK solution result of the measuring point and the reliability of the PPK solution result according to the solution results of all the starting points of the measuring point and the fixed results in the solution results.

[0112] The higher the reliability, the higher the corresponding weight of the PPK solution result.

[0113] Specifically, step 1043 includes:

[0114] The mobile station verifies the RTK solution result according to the PPK solution result of the measurement point, and obtains weighted positioning information of the RTK solution result and the PPK solution result according to the verification result, wherein the higher the reliability of the solution result, the higher the weight of the solution result in the weighted positioning information.

[0115] The duration between adjacent starting points is a fixed value, and the preset rules include:

[0116] The mobile station performs PPK solution from the starting point in time sequence to obtain the PPK solution result of each starting point;

[0117] The mobile station performs PPK solution from a starting point in reverse time sequence to obtain a PPK solution result for each starting point.

[0118] Specifically, step 1043 includes:

[0119] Using the starting points known as fixed results on the measuring point, the solution results of the starting points on the measuring point other than the starting points of the fixed results are inferred to obtain all the starting points on the measuring point that are fixed results;

[0120] The PPK solution result of the measuring point and the reliability of the PPK solution result are obtained according to the number of fixed results.

[0121] In other embodiments, step 104 includes:

[0122] Calling the PPK solution engine to perform PPK solution at the measurement point to obtain a starting point for the first fixed result;

[0123] Taking the starting point of the first fixed result as the starting point, reversely calculate the PPK solution results of the adjacent starting points in turn until the continuous starting points of all fixed results in the reverse calculation process are obtained, and the built-in memory stores the base station signal and GNSS signal of the next starting point;

[0124] Taking the starting point of the first fixed result as the starting point, the PPK solution results of the adjacent starting points are forwardly calculated in sequence until a preset number of starting points of the fixed results are obtained;

[0125] The PPK solution result of the measuring point is obtained based on the solution results of all the starting points with fixed results.

[0126] The above steps may be specifically included after step 1043 .

[0127] The method of taking the starting point of the first fixed result as the starting point and sequentially forward calculating the PPK solution results of adjacent starting points until obtaining the starting points of a preset number of fixed results includes:

[0128] Taking the starting point of the first fixed result as the starting point, forwardly calculate the PPK solution results of the adjacent starting points, and determine whether the PPK solution result of the starting point is a fixed result. If not, take the starting point of the next fixed result of the starting point of the first fixed result as the starting point of the first fixed result, and reversely calculate the PPK solution results of the adjacent starting points again until the continuous starting points of all fixed results in the reverse calculation process are obtained. At the same time, the built-in memory stores the base station signal and GNSS signal of the next starting point.

[0129] The measuring method comprises:

[0130] The user configures the relevant parameters of the mobile station's quasi-real-time PPK solution engine through commands, and the relevant parameters include the starting time, filtering direction and calculation times;

[0131] The base station signal and GNSS signal in the built-in memory are transmitted to the host computer, and the host computer uses the base station signal and GNSS signal to perform PPK solution to obtain the positioning information of all measurement points.

[0132] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A measurement method for GNSS, used in a measurement system, characterized in that: The measurement system includes a base station and at least one mobile station, the mobile station includes a built-in memory, an RTK solution engine and a PPK solution engine, and the measurement method includes: The mobile station receives a base station signal and a GNSS signal of a reference station at a measurement point; The base station signal and the GNSS signal are solved by the RTK solution engine to obtain the RTK solution result, and the base station signal and the GNSS signal are stored in the built-in memory in a time sequence; Determine whether the RTK solution result meets the preset conditions, and if not, call the PPK solution engine to perform PPK solution at the measurement point to obtain the PPK solution result; The mobile station obtains the positioning information of the measuring point according to the RTK solution result and the PPK solution result; The determining whether the RTK solution result meets the preset conditions includes: Determine whether the RTK solution result meets the preset conditions, and if so, the mobile station obtains the positioning information of the measurement point according to the RTK solution result; The calling the PPK solution engine to perform PPK solution at the measurement point to obtain a PPK solution result includes: Calling the PPK solution engine to perform PPK solution at the measurement point according to a preset starting point to obtain a starting point solution result; Calculate the solution results of all the starting points of the measurement points according to the preset rules; The PPK solution result of the measuring point and the reliability of the PPK solution result are obtained according to the solution results of all the starting points of the measuring point and the fixed results in the solution results.

2. The measuring method according to claim 1, characterized in that: The mobile station obtains the positioning information of the measuring point according to the RTK solution result and the PPK solution result, including: The mobile station verifies the RTK solution result according to the PPK solution result of the measurement point, and obtains weighted positioning information of the RTK solution result and the PPK solution result according to the verification result, wherein the higher the reliability of the solution result, the higher the weight of the solution result in the weighted positioning information.

3. The measuring method according to claim 1, characterized in that: The duration between adjacent starting points is a fixed value, and the preset rules include: The mobile station performs PPK solution from the starting point in time sequence to obtain the PPK solution result of each starting point; and / or, The mobile station performs PPK solution from a starting point in reverse time sequence to obtain a PPK solution result for each starting point.

4. The measuring method according to claim 3, characterized in that: The obtaining of the PPK solution result of the measuring point and the reliability of the PPK solution result according to the solution results of all the starting points of the measuring point and the fixed results in the solution results includes: Using the starting points known as fixed results on the measuring point, the solution results of the starting points on the measuring point other than the starting points of the fixed results are inferred to obtain all the starting points on the measuring point that are fixed results; The PPK solution result of the measuring point and the reliability of the PPK solution result are obtained according to the number of fixed results.

5. The measuring method according to claim 1, characterized in that: The calling the PPK solution engine to perform PPK solution at the measurement point to obtain a PPK solution result includes: Calling the PPK solution engine to perform PPK solution at the measurement point to obtain a starting point for the first fixed result; Taking the starting point of the first fixed result as the starting point, reversely calculate the PPK solution results of the adjacent starting points in turn until the continuous starting points of all fixed results in the reverse calculation process are obtained, and the built-in memory stores the base station signal and GNSS signal of the next starting point; Taking the starting point of the first fixed result as the starting point, the PPK solution results of the adjacent starting points are forwardly calculated in sequence until a preset number of starting points of the fixed results are obtained; Obtain the PPK solution result of the measuring point based on the solution results of all the starting points with fixed results; The method of taking the starting point of the first fixed result as the starting point and sequentially forward calculating the PPK solution results of adjacent starting points until obtaining the starting points of a preset number of fixed results includes: Taking the starting point of the first fixed result as the starting point, forwardly calculate the PPK solution results of the adjacent starting points, and determine whether the PPK solution result of the starting point is a fixed result. If not, take the starting point of the next fixed result of the starting point of the first fixed result as the starting point of the first fixed result, and reversely calculate the PPK solution results of the adjacent starting points again until the continuous starting points of all fixed results in the reverse calculation process are obtained. At the same time, the built-in memory stores the base station signal and GNSS signal of the next starting point.

6. The measuring method according to claim 2, characterized in that: The measuring method comprises: The user configures the relevant parameters of the mobile station's quasi-real-time PPK solution engine through commands, wherein the relevant parameters include the start time, filtering direction and number of calculations; and / or, The base station signal and GNSS signal in the built-in memory are transmitted to the host computer, and the host computer uses the base station signal and GNSS signal to perform PPK solution to obtain the positioning information of all measurement points.

7. A measurement system for GNSS, characterized in that: The measurement system is used to implement the measurement method according to any one of claims 1 to 6, and the measurement system includes a reference station and at least one mobile station.

8. An RTK receiver, characterized in that: The RTK receiver is used for a reference station and / or a mobile station in the surveying system according to claim 7.

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