A calibration method and calibration unit for a high-precision differential pressure altimetry system

Abstract

The present invention relates to a calibration method and calibration unit of a high-precision differential pressure altimetry system, the method comprising first selecting a pressure measurement module that meets the accuracy requirements of the differential pressure altimetry system; the pressure measurement module is used to measure pressure data; then, for the selected pressure measurement modules, one of them is selected in turn as a reference station pressure measurement module, and the pressure data measured by other pressure measurement modules are calibrated, and the reference station pressure measurement module and the pressure measurement modules to be deployed to different observation stations are selected by using the mean of the calibrated pressure data and the standard deviation of the pressure difference measured by the reference station and other pressure measurement modules, so as to complete the calibration of the differential pressure altimetry system; the differential pressure altimetry system is formed by the deployment of the selected pressure measurement modules. The calibration unit comprises a test box, a data acquisition unit, a data processing unit, a module power supply unit and a display unit. The present invention solves the problem that the accuracy of the differential pressure altimetry system diverges over time.

Description

Technical Field

[0001] The present invention relates to the field of air pressure altimetry, and in particular to a calibration method and a calibration unit for a high-precision differential air pressure altimetry system. Background Art

[0002] The use of air pressure for altitude measurement has long been used in the field of aircraft navigation and is often used to assist GNSS altitude enhancement.

[0003] The GNSS positioning system is currently relatively mature and can provide users with accurate positioning services in a wide range of unobstructed outdoor spaces. However, it cannot guarantee positioning accuracy, reliability, and continuity in densely populated urban areas or tunnels. In addition, for indoor environments, since GNSS signals are often blocked by buildings, positioning accuracy drops rapidly and may even fail to be performed normally. In addition, when the satellite geometry is not ideal, the elevation direction is more easily affected than the horizontal direction, and the accuracy drops significantly. In order to solve the above problems, some elevation measurement schemes have been proposed, among which the most widely used is the method of measuring altitude using air pressure information.

[0004] In the article "Virtual Constellation of Barometric Altimetry Applied to CAPS" written by Academician Ai Guoxiang, it is proposed that the basic principle of barometric altitude measurement is that the atmospheric pressure decreases with increasing altitude in the gravity field. By using barometric pressure sensors to measure meteorological parameters, the relative altitude of the base station and the user can be calculated.

[0005]

[0006] The above equation (1) is called the Laplace pressure height equation.

[0007] Among them, the air pressure P and P 0 Corresponding to the user height h and the base station height h respectively 0 ; atmospheric pressure P and P 0 The height difference between the two is hh 0 = Δh; the average temperature T in the atmosphere involved m =(T 0 +T R ) / 2,T 0 is the reference point temperature in degrees Celsius, T R is the user-measured temperature in degrees Celsius. Formula (1) is the basic formula for determining altitude using air pressure.

[0008] The reference station mentioned in this article is a fixed-position air pressure and temperature observation station that needs to be equipped with an air pressure measurement module. The air pressure measurement module needs to be installed at a fixed height h of the reference station. 0The user is a movable air pressure and temperature observation station, which needs to be equipped with an air pressure measurement module. It is installed at the user's fixed position h to collect the user's air pressure and temperature data in real time. The air pressure measurement module (also called air pressure height measurement module) includes an air pressure sensor chip for measuring air pressure data.

[0009] With the in-depth research and application of barometric altimetry, it was found that there are still some problems in barometric altimetry positioning. Lai Qifeng's patent "Altitude positioning method for real-time calibration of barometric altimetry results using satellite positioning information" points out that barometric altimetry has the characteristics of relatively high accuracy and short-term stability. However, when working for a long time, it will be affected by the environment (wind speed, temperature, humidity, etc.), and drift over time will occur, resulting in inconsistent measurement results for several consecutive days.

[0010] Based on the above technical background and application background, a method for constructing high-precision differential pressure altimetry is proposed. Summary of the invention

[0011] The purpose of the present invention is to overcome the disadvantage of the traditional differential pressure altimetry system that the accuracy of the differential pressure altimetry diverges after long-term operation due to the individual differences of sensors. The present invention discloses a system solution to improve the accuracy of differential pressure altimetry.

[0012] The present invention proposes a calibration method for a high-precision differential air pressure altimetry system, the method comprising:

[0013] Firstly, a pressure measurement module that meets the accuracy requirements of the differential pressure height measurement system is selected; the pressure measurement module is used to measure the pressure data;

[0014] Then, for the selected pressure measurement modules, one of them is selected in turn as the base station pressure measurement module, and the pressure data measured by other pressure measurement modules are calibrated. The pressure measurement module as the base station and the pressure measurement modules to be deployed to different observation stations are selected by using the mean of the calibrated pressure data and the standard deviation of the pressure difference measured by the base station and other pressure measurement modules to complete the calibration of the differential pressure altimetry system; the differential pressure altimetry system is formed by the deployment of the selected pressure measurement modules.

[0015] As one of the improvements of the above technical solution, the method comprises the following steps:

[0016] Step 1: According to the requirements for the accuracy of the differential air pressure measurement system, select an air pressure measurement module that can meet the accuracy requirements;

[0017] Step 2: according to the number of observation stations where the air pressure measurement modules are to be deployed for the altitude measurement task, the number M of the air pressure measurement modules to be selected is set to be much larger than the number of observation stations;

[0018] Step 3: Place all selected air pressure measurement modules in an indoor constant temperature and pressure sealed box, and collect air pressure data measured by all air pressure measurement modules;

[0019] Step 4: Preprocess the collected air pressure data to obtain the air pressure data of all air pressure measurement modules in a certain time period T. 0 The same number of pressure values ​​between ~T;

[0020] Step 5: Select the i-th air pressure measurement module as the reference station air pressure measurement module, i∈(1, ..., M-1, M), calibrate the air pressure value of the j-th air pressure measurement module at time t to obtain a new air pressure value, j∈(1, ..., M-1, M), j≠i;

[0021] Step 6: Calculate the standard deviation of the difference between the new air pressure value after calibration of the jth air pressure measurement module and the original air pressure value of the ith air pressure measurement module at time t.

[0022] Step 7: Repeat step 6 to traverse all air pressure measurement modules other than i and obtain M-1 And for M-1 Summing to get

[0023] Step 8: Reselect the kth air pressure measurement module as the base station air pressure measurement module and repeat steps 5-7 to obtain

[0024] Step 9: Repeat step 8 to get a total of M

[0025] Step 10. In M Find the smallest The corresponding x-th air pressure measurement module is the base station air pressure measurement module;

[0026] Step 11: Analyze the M-1 barometric pressure measurement modules obtained by taking the xth barometric pressure measurement module as the reference station barometric pressure measurement module. Culling The pressure measurement modules with accuracy greater than the differential pressure altimetry system requirement are used as pressure measurement modules to be deployed at different observation stations, thereby completing the calibration of the differential pressure altimetry system.

[0027] As one of the improvements of the above technical solution, the number M of air pressure measurement modules selected in step 2 is at least several times the scale of the observation station where the air pressure measurement modules need to be deployed.

[0028] As one of the improvements of the above technical solution, the step 3 places all the selected air pressure measurement modules in an indoor constant temperature and pressure closed box, and collects the air pressure data measured by all the air pressure measurement modules, and the requirements include:

[0029] 3.1) All air pressure measurement modules are placed at the same height in the constant temperature and pressure box;

[0030] 3.2) All air pressure measurement modules are powered by the same external DC power supply and cables of the same length, and there is no heat source inside the box;

[0031] 3.3) Collect the data output by all air pressure measurement modules through the serial port, add time stamp to the data, and store it in real time;

[0032] 3.4) The test time shall not be less than the set time period.

[0033] As one of the improvements of the above technical solution, in step 4, the data output by all the collected air pressure measurement modules are preprocessed, including:

[0034] 4.1) Time preprocessing: align the start and end times of the air pressure data output by all air pressure measurement modules;

[0035] 4.2) Data preprocessing: remove bad values ​​in the original pressure data output by all pressure measurement modules; remove the time points with no data at the same time from the pressure data output by all pressure measurement modules.

[0036] As one of the improvements of the above technical solution, the step 5 specifically includes:

[0037] The pressure measurement module of the i-th pressure measurement module is used as the reference station, and the new pressure value of the pressure measurement module of the j-th block after calibration at time t is The expression is:

[0038]

[0039]

[0040] in, is the original air pressure value of the air pressure measurement module of the i-th block at time t; is the original air pressure value of the air pressure measurement module of the jth block at time t; ΔμP i j T 0 The average value of the difference between the original air pressure value of the air pressure measurement module of the i-th block and the original air pressure value of the air pressure measurement module of the j-th block in the time period of T ~ T; N is the average value of the difference between the original air pressure value of the air pressure measurement module of the i-th block and the original air pressure value of the air pressure measurement module of the j-th block in the time period of T 0 The number of air pressure values ​​in the time period from A to T.

[0041] As one of the improvements of the above technical solution, in step 6, the standard deviation of the difference between the new air pressure value after calibration of the j-th air pressure measurement module and the original air pressure value of the i-th air pressure measurement module at time t is calculated. The expression is:

[0042]

[0043] in, is the new air pressure value after calibration of the j-th air pressure measurement module at time t, is the original air pressure value of the i-th air pressure measurement module at time t.

[0044] The present invention also proposes a calibration unit for a high-precision differential pressure altimetry system, which is calibrated based on one of the calibration methods for a high-precision differential pressure altimetry system described above, and the calibration unit comprises: a test box, a data acquisition unit and a data processing unit;

[0045] The test box is provided with a plurality of air pressure measurement modules, which are used to select a suitable air pressure measurement module according to the accuracy requirement of the differential air pressure height measurement system to measure the air pressure data;

[0046] The data acquisition unit is used to collect the air pressure data measured by the selected air pressure measurement module and transmit it to the data processing unit;

[0047] The data processing unit is used to process the collected air pressure data and select the air pressure measurement module as the reference station and the air pressure measurement modules to be deployed to different observation stations.

[0048] As one of the improvements of the above technical solution, the calibration unit further includes:

[0049] A module power supply unit, used to provide power to each air pressure measurement module; and

[0050] The display unit is used to display the air pressure measurement module selected by the data processing unit.

[0051] As one of the improvements of the above technical solution, the test box is a constant temperature and pressure closed box.

[0052] The present invention has the following beneficial effects:

[0053] 1. The altitude value calculated by differential pressure altimetry using the pressure measurement module optimized and calibrated by the method of the present invention is much more accurate and stable than the altitude value calculated by traditional differential pressure altimetry.

[0054] 2. The present invention solves the problem that the accuracy of the differential pressure altitude measurement system diverges over time, and can achieve long-term stable and high-precision altitude output. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A schematic diagram of the process of selecting and calibrating an air pressure measurement module and using the calibrated altimeter system to perform altimeter measurement is provided in the method of the present invention;

[0056] Figure 2 It is a block diagram of the structure of the calibration unit according to an embodiment of the present invention;

[0057] Figure 3 It is a structural schematic diagram of the test box of the calibration unit of the present invention and the air pressure measurement module in the test box. DETAILED DESCRIPTION

[0058] Before deploying the differential pressure altimetry system, the present invention first needs to preliminarily select the pressure measurement module group to select the pressure measurement module with strong measurement stability and consistency; then the selected pressure measurement modules are uniformly calibrated; finally, the reference station and the observation station are deployed to carry out user-side differential pressure measurement. The differential pressure altimetry system constructed by the pressure measurement modules selected and calibrated by this method greatly improves and enhances the user-side measurement accuracy.

[0059] The purpose of the present invention is to provide a method for constructing high-precision differential pressure altimetry, which can select and calibrate the pressure measurement module before the differential pressure altimetry is used, so that the differential pressure altimetry can output high-precision altimetry results. This method targets the source of system errors in the pressure differential station group, and optimizes the accuracy of the pressure altimetry system by optimizing the differential reference station and the user end. When optimizing the pressure measurement module group, the stability and consistency of the device measured by a long-term static constant temperature and constant pressure box are considered. The stability is measured by the mean of the measured value difference, and the consistency is measured by the standard deviation of the difference. The specific invention steps are as follows:

[0060] Step 1: According to the system's requirements for the accuracy of the differential pressure measurement system, select a pressure measurement module that can meet the accuracy requirements according to the device manual's specifications;

[0061] Step 2: According to the scale of the user end and the model of the selected air pressure measurement module, the quantity M of each air pressure measurement module purchased is at least twice the scale of the user end; (In fact, the quantity of air pressure measurement modules is not limited to twice the scale of the user end)

[0062] Step 3: In a closed box with constant temperature and pressure, carry out data collection of the air pressure measurement module. The specific method is as follows:

[0063] 3.1 All the air pressure measurement modules to be tested are placed at the same height in the constant temperature and pressure box;

[0064] 3.2 All the air pressure measurement modules to be tested are powered by the same external DC power supply and cables of the same length, and there is no heat source inside the box;

[0065] 3.3 Collect the data output by all the air pressure measurement modules to be tested through the serial port, and store the data in the computer in real time after being stamped with the local time stamp of the computer;

[0066] 3.4 The test time shall not be less than 1 week;

[0067] Step 4: Process the collected data output by all the air pressure measurement modules as follows:

[0068] 4.1 Time preprocessing: First, align the start and end times of the air pressure data output by all the air pressure measurement modules to be tested;

[0069] 4.2 Data preprocessing. Remove bad values ​​from the raw pressure data output by all the pressure measurement modules to be tested. Remove the time points with no data at the same time from the pressure data output by all the pressure measurement modules to be tested;

[0070] 4.3 Get all air pressure measurement modules at time T 0 The same number of pressure values ​​between ~T.

[0071] Step 5: In T 0 During the time period from t to t, if the i-th pressure measurement module is used as the pressure measurement module of the reference station, the new pressure value of the j-th pressure measurement module after calibration at time t is for:

[0072]

[0073]

[0074] in, is the original air pressure value of the air pressure measurement module of the i-th block at time t; is the original air pressure value of the air pressure measurement module of the jth block at time t; T 0 The average value of the difference between the original air pressure value of the air pressure measurement module of the i-th block and the original air pressure value of the air pressure measurement module of the j-th block in the time period of T ~ T; N is the average value of the difference between the original air pressure value of the air pressure measurement module of the i-th block and the original air pressure value of the air pressure measurement module of the j-th block in the time period of T 0 The number of air pressure values ​​in the time period from A to T.

[0075] Step 6: At time t, the new air pressure value after calibration of the jth air pressure measurement module The original air pressure value of the i-th air pressure measurement module The standard deviation of the difference σ j , the expression is:

[0076]

[0077] in, is the new air pressure value after calibration of the j-th air pressure measurement module at time t, is the original air pressure value of the i-th air pressure measurement module at time t.

[0078] Step 7: Traverse all air pressure measurement modules other than i and obtain M-1 Find all M-1 , let it be

[0079] Step 8: Reselect a pressure measurement module as the pressure height measurement module of base station k, and repeat steps 1-4 to obtain

[0080] Step 9: Repeat step 8 to reselect the barometric altimetry module of the base station, and obtain M

[0081] Step 10. Select The barometric pressure measurement module x is selected as the base station barometric pressure altimeter module of the group.

[0082] Step 11: Determine the air pressure measurement module x as the base station air pressure height measurement module and analyze M-1 Culling The pressure measurement module with a precision greater than that required by the differential pressure altimeter system, and the remaining pressure measurement altimeter modules can be used as user terminals.

[0083] Step 12: Fixedly deploy the base station pressure measurement module and accurately measure the altitude h where the base station pressure altimeter module is located 0 , according to the differential pressure altimetry formula (1), calculate the user's altitude.

[0084] The technical solution provided by the present invention is further illustrated below in conjunction with embodiments.

[0085] Example 1

[0086] The method for constructing high-precision differential pressure height measurement in embodiment 1 of the present invention is as follows: Figure 1 As shown, the steps include: Step 1, according to the system's requirements for the accuracy of the differential air pressure measurement system, select an air pressure measurement module that can meet the accuracy requirements according to the device manual indicator description;

[0087] Step 2: According to the scale of the user end and the model of the selected air pressure measurement module, the quantity M of each air pressure measurement module purchased is at least twice the scale of the user end; (It should be noted here that it is not limited to 2 times and can be set according to experience or actual conditions)

[0088] Step 3: In a constant temperature and pressure sealed box, carry out data collection of the air pressure measurement module. Specific methods:

[0089] 3.1 All the air pressure measurement modules to be tested are placed at the same height in the constant temperature and pressure box;

[0090] 3.2 All the air pressure measurement modules to be tested are powered by the same external DC power supply and cables of the same length, and there is no heat source inside the box;

[0091] 3.3 Collect the data output by all the air pressure measurement modules to be tested through the serial port, and store the data in the computer in real time after being stamped with the local time stamp of the computer;

[0092] 3.4 The test time shall not be less than 1 week;

[0093] Step 4: Process the collected data output by all the air pressure measurement modules as follows:

[0094] 4.1 Time preprocessing: First, align the start and end times of the air pressure data output by all the air pressure measurement modules to be tested;

[0095] 4.2 Data preprocessing. Remove bad values ​​from the raw pressure data output by all the pressure measurement modules to be tested. Remove the time points with no data at the same time from the pressure data output by all the pressure measurement modules to be tested;

[0096] 4.3 Get all air pressure measurement modules at time T 0 The same number of pressure values ​​between ~T.

[0097] Step 5: In T 0 In the time period from t to t, if the i-th pressure measurement module is used as the reference station pressure measurement module, the new pressure value of the j-th pressure measurement module after calibration at time t is for:

[0098]

[0099]

[0100] in, is the original air pressure value of the air pressure measurement module of the i-th block at time t; is the original air pressure value of the air pressure measurement module of the jth block at time t; T 0 The average value of the difference between the original air pressure value of the air pressure measurement module of the i-th block and the original air pressure value of the air pressure measurement module of the j-th block in the time period of T ~ T; N is the average value of the difference between the original air pressure value of the air pressure measurement module of the i-th block and the original air pressure value of the air pressure measurement module of the j-th block in the time period of T 0 The number of air pressure values ​​in the time period from A to T.

[0101] Step 6: At time t, the new air pressure value after calibration of the jth air pressure measurement module The original air pressure value of the i-th air pressure measurement module The standard deviation of the difference σ j , the expression is:

[0102]

[0103] in, is the new air pressure value after calibration of the j-th air pressure measurement module at time t, is the original air pressure value of the i-th air pressure measurement module at time t.

[0104] Step 7: Traverse all air pressure measurement modules other than i and obtain M-1 Find all M-1 , let it be

[0105] Step 8. Reselect a pressure altimeter module of base station k and repeat steps 1-4 to obtain

[0106] Step 9: Repeat step 8 to reselect the base station pressure height measurement module, and obtain a total of M

[0107] Step 10. Select The barometric pressure measurement module x is selected as the base station barometric pressure altimeter module of the group.

[0108] Step 11: Determine the air pressure measurement module x as the base station air pressure height measurement module and analyze M-1 Culling The pressure measurement modules with a precision greater than that required by the differential pressure altimeter system and the remaining pressure measurement modules can be used as user-side pressure altimeter modules.

[0109] Step 12: Fixedly deploy the base station barometric altimeter module and accurately measure the altitude h where the base station barometric altimeter module is located. 0 , according to the differential pressure altimetry formula (1), calculate the user's altitude.

[0110] The purpose of step 5 is to eliminate the deviation between the pressure data output by each pressure measurement module due to the individual differences of the pressure sensor chip, so that the altitude resolution calculated by the differential pressure system can reflect the best altitude resolution performance of the pressure sensor chip, thereby improving the altitude measurement accuracy of the differential pressure altitude measurement system.

[0111] The different standard deviations of the pressure data output by each pressure measurement module due to individual differences in the pressure sensor chips will cause the deviations between the pressure data output by each pressure measurement module, which have been eliminated in step 5, to gradually become larger over time.

[0112] The purpose of step 6 is to eliminate the pressure measurement modules whose standard deviation is greater than the accuracy requirement of the differential pressure measurement system, so that the deviation between the pressure data output by the eliminated pressure measurement modules will not gradually increase over time. At the same time, the best pressure measurement module is selected as the reference station pressure measurement module and the remaining pressure measurement modules are selected as the observation station pressure measurement modules.

[0113] In this way, the height values ​​of each observation station calculated according to the differential pressure altimetry formula (1) will not become worse with the passage of time, and thus the system height measurement accuracy of the differential pressure altimetry system will not decrease with the passage of time.

[0114] Example 2

[0115] like Figure 2 As shown, it is a schematic diagram of the structure of the calibration unit of the high-precision differential air pressure altimetry system of Example 2 of the present invention; the calibration unit includes: a test box, a data acquisition unit, a data processing unit, a module power supply unit and a display unit;

[0116] The test box is a constant temperature and constant pressure closed box, in which a plurality of air pressure measurement modules are arranged, and is used to select a suitable air pressure measurement module according to the accuracy requirement of the differential air pressure height measurement system to measure the air pressure data;

[0117] A data acquisition unit, used to collect the air pressure data measured by the selected air pressure measurement module and transmit it to the data processing unit;

[0118] A data processing unit is used to process the collected air pressure data and select the air pressure altimetry module as the reference station and the air pressure altimetry modules to be deployed at different observation stations;

[0119] A module power supply unit, used to provide power to each air pressure measurement module;

[0120] The display unit is used to display the air pressure measurement module selected by the data processing unit.

[0121] After selecting a pressure measurement module group that meets the system accuracy requirements in a constant temperature and pressure box, the present invention selects a reference station pressure altimetry module and a user-end pressure altimetry module that meet the requirements from the group of pressure measurement modules, and then performs differential pressure altimetry to output long-term stable and non-drifting elevation information.

[0122] like Figure 3, which is a schematic structural diagram of a constant temperature and constant pressure test box and a test air pressure measurement module in the box according to Embodiment 2 of the present invention.

[0123] After the differential pressure altimetry system is calibrated by the present invention, the selected pressure measurement module is deployed, and the differential pressure altimetry system is used to measure the altitude, including:

[0124] The selected base station pressure altimeter module is fixedly deployed at a set position, the pressure data at that position is measured, and the altitude of the base station pressure altimeter module is accurately measured; at the same time, other pressure measurement modules are deployed at different observation stations, and the pressure data at the corresponding observation stations are measured; according to the differential pressure altimeter formula (1), the altitude values ​​of the pressure measurement modules at each observation station are calculated.

[0125] From the above specific description of the present invention, it can be seen that the method of the present invention can effectively solve the shortcomings of the differential pressure altimetry system that the short-term accuracy of the altitude measurement is good but the long-term accuracy divergence due to the individual differences of the sensors, and realize the differential pressure altimetry system with high accuracy and long-term stable altitude output without drift.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A calibration method for a high-precision differential pressure altimetry system, the method comprising: First, select a pressure measurement module that meets the accuracy requirements of the differential pressure height measurement system; The air pressure measurement module is used to measure air pressure data; Then, for the selected pressure measurement modules, one of them is selected as the reference station pressure measurement module in turn, and the pressure data measured by other pressure measurement modules are calibrated. The pressure measurement module as the reference station and the pressure measurement modules to be deployed at different observation stations are selected by using the mean of the calibrated pressure data and the standard deviation of the pressure difference measured by the reference station and other pressure measurement modules, thus completing the calibration of the differential pressure altimetry system. The differential barometric altimetry system is formed by deploying selected barometric measurement modules.

2. The calibration method of the high-precision differential pressure altimetry system according to claim 1, characterized in that: The method comprises the following steps: Step 1: According to the requirements for the accuracy of the differential air pressure height measurement system, select an air pressure measurement module that can meet the accuracy requirements; Step 2: according to the number of observation stations of the differential pressure altimetry system to be deployed, the number M of the pressure measurement modules to be selected is set to at least twice the size of the user end; Step 3: Place all selected air pressure measurement modules in an indoor constant temperature and pressure sealed box, and collect air pressure data measured by all air pressure measurement modules; Step 4: pre-process the collected air pressure data to obtain the same number of air pressure values ​​of all air pressure measurement modules in a certain time period T0-T; Step 5: Select the i-th air pressure measurement module as the reference station air pressure measurement module, i∈(1, ..., M-1, M), calibrate the air pressure value of the j-th air pressure measurement module at time t to obtain a new air pressure value, j∈(1, ..., M-1, M), j≠i; Step 6: Calculate the standard deviation of the difference between the new air pressure value after calibration of the jth air pressure measurement module and the original air pressure value of the ith air pressure measurement module at time t. Step 7: Repeat step 6 to traverse all air pressure measurement modules other than i and obtain M-1 And for M-1 Summing to get Step 8: Reselect the kth air pressure measurement module as the base station air pressure measurement module and repeat steps 5-7 to obtain Step 9: Repeat step 8 to get a total of M Step 10. In M Find the smallest The corresponding x-th air pressure measurement module is the base station air pressure measurement module; Step 11: Analyze the M-1 barometric pressure measurement modules obtained by taking the xth barometric pressure measurement module as the reference station barometric pressure measurement module. Culling The pressure measurement modules with accuracy greater than the differential pressure altimetry system requirement are used as pressure measurement modules to be deployed at different observation stations, thereby completing the calibration of the differential pressure altimetry system.

3. The calibration method of the high-precision differential pressure altimetry system according to claim 2, characterized in that: The step 3 places all selected air pressure measurement modules in an indoor constant temperature and pressure sealed box, and collects the air pressure data measured by all air pressure measurement modules, and the requirements include: 3.1) All air pressure measurement modules are placed at the same height in the constant temperature and pressure box; 3.2) All air pressure measurement modules are powered by the same external DC power supply and cables of the same length, and there is no heat source inside the box; 3.3) Collect the data output by all air pressure measurement modules through the serial port, add time stamp to the data, and store it in real time; 3.4) The test time shall not be less than the set time period.

4. The calibration method of the high-precision differential pressure altimetry system according to claim 2, characterized in that: In step 4, the collected data output by all air pressure measurement modules are preprocessed, including: 4.1) Time preprocessing: align the start and end times of the air pressure data output by all air pressure measurement modules; 4.2) Data preprocessing: remove bad values ​​in the original air pressure data output by all air pressure measurement modules; remove the time points with no data at the same time from the air pressure data output by all air pressure measurement modules.

5. The calibration method of the high-precision differential pressure altimetry system according to claim 2, characterized in that: The step 5 specifically includes: The pressure measurement module of the i-th pressure measurement module is used as the reference station, and the new pressure value of the pressure measurement module of the j-th block after calibration at time t is The expression is: in, is the original air pressure value of the air pressure measurement module of the i-th block at time t; is the original air pressure value of the air pressure measurement module of the jth block at time t; is the average of the difference between the original air pressure value of the air pressure measurement module of the i-th block and the original air pressure value of the air pressure measurement module of the j-th block in the time period from T0 to T; N is the number of air pressure values ​​in the time period from T0 to T.

6. The calibration method of the high-precision differential pressure altimetry system according to claim 2, characterized in that: In step 6, the standard deviation of the difference between the new air pressure value after calibration of the jth air pressure measurement module and the original air pressure value of the ith air pressure measurement module at time t is calculated. The expression is: in, is the new air pressure value after calibration of the j-th air pressure measurement module at time t, is the original air pressure value of the i-th air pressure measurement module at time t.

7. A calibration unit of a high-precision differential pressure altimetry system, calibrated based on the calibration method of a high-precision differential pressure altimetry system according to any one of claims 1 to 6, characterized in that: The calibration unit includes: a test box, a data acquisition unit and a data processing unit; The test box is provided with a plurality of air pressure measurement modules, which are used to select a suitable air pressure measurement module according to the accuracy requirement of the differential air pressure height measurement system to measure the air pressure data; The data acquisition unit is used to collect the air pressure data measured by the selected air pressure measurement module and transmit it to the data processing unit; The data processing unit is used to process the collected air pressure data and select the air pressure measurement module as the reference station and the air pressure measurement modules to be deployed to different observation stations.

8. The calibration unit of the high-precision differential pressure altimetry system according to claim 7, characterized in that: The calibration unit also includes: A module power supply unit, used to provide power to each air pressure measurement module; and The display unit is used to display the air pressure measurement module selected by the data processing unit.

9. The calibration unit of the high-precision differential pressure altimetry system according to claim 7, characterized in that: The test box is a constant temperature and pressure closed box.

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