CN101598780B - Local airport monitoring method, device and system therefor - Google Patents

Abstract

The present invention provides a local area airport monitoring method, device and system, the method comprising: receiving satellite data sent by each receiver, calculating the pseudo-range correction value corresponding to each receiver; selecting one receiver as a pseudo-airborne User, calculate the pseudo-range correction value positioning error of the pseudo-airborne user; calculate the monitoring system positioning error of the pseudo-airborne user, and calculate the ground monitoring of the pseudo-airborne user according to the positioning error of the monitoring system and the information broadcast error of the wide-area enhancement system Protection level: compare the ground monitoring protection level of all visible satellite combinations of the pseudo-airborne user with the preset alarm limit value of the airborne user, and output the best satellite combination according to the comparison result. The present invention calculates the error of the pseudorange correction value and the error of the monitoring system for the airborne user at the monitoring end on the ground, and completes the selection of the best visible satellite combination for the airborne user through the detection of the ground monitoring protection level, reducing The calculation burden of the airborne user is reduced, and the real-time performance is improved.

Description

Local airport monitoring method, device and system

technical field

The embodiment of the present invention relates to the technical field of satellite navigation, in particular to a local airport monitoring method, device and system. the

Background technique

When the satellite navigation system is used in civil aviation, it usually must meet the four performance indicators of accuracy, integrity, continuity and availability. Among them, accuracy refers to the difference between the measured position and the true position of the navigation system at any time; integrity refers to the ability of the system to issue a warning or shut down in time when the system cannot provide navigation services; Ability to provide services during the process; usability refers to the ability of the system to be used for navigation when the user needs it. However, since the current satellite navigation system is usually affected by factors such as the number of available satellites, the atmosphere, the ionosphere, and thunderclouds, as well as the dynamic behavior of the aircraft, whether it is the US Global Positioning System (Global Positioning System; hereinafter referred to as GPS) , or Russia's Global Navigation Satellite System (Global Navigation Satellite System; hereinafter referred to as GLONASS), cannot fully meet the navigation performance requirements in the above aspects. Therefore, in order to improve the integrity, accuracy, availability and continuous service of the satellite navigation system, the satellite navigation augmentation system has been formed. It uses some ground and satellite facilities, based on the selection of differential technology and pseudolite technology. The performance of satellite navigation systems can be improved. the

The current satellite navigation augmentation system can be divided into three types: ground-based augmentation system, satellite-based augmentation system and space-based augmentation system. Among them, the representative of the ground-based augmentation system is the Local Area Augmentation System (LAAS) of the United States. . The differential technique used by LAAS is based on generating a correction value for all expected common errors between the local reference station and the user station. Therefore, LAAS can only broadcast navigation correction information within a "local" range of about 20 nautical miles, and its service Space only includes airports within the region. In addition, due to the impact of ionospheric storms, the integrity of LAAS cannot be guaranteed, making the certification of LAAS very difficult. the

Representatives of satellite-based augmentation systems are the Wide Area Augmentation System (Wide Area Augmentation System; hereinafter referred to as WAAS) of the United States and the European Geostationary Navigation Overlay Service (EGNOS) system of the European Union. These two systems broadcast correction information to users through geostationary orbit satellites (Geostationary Orbit; hereinafter referred to as GEO), but due to lack of local monitoring, their integrity cannot meet the performance requirements of civil aviation precision approach. the

The representative of the space-based augmentation system is the receiver autonomous integrity monitoring system (Receiver Autonomous Integrity Monitoring; hereinafter referred to as RAIM). Although RAIM is currently a simple and effective integrity monitoring method, there are still usability problems in the RAIM method. The so-called availability of RAIM means that at certain time and space points, RAIM monitoring cannot be performed or the monitoring results of RAIM cannot guarantee to meet the requirements of false alarm rate and missed detection rate at the same time. There are two main factors that lead to RAIM availability problems: one is the insufficient number of observation satellites, RAIM needs at least 5 satellites at the same time to perform redundant information consistency checks to detect faults, and at least 6 satellites to perform fault identification operations. That is to say, at some time and space points, the number of satellites is insufficient and RAIM monitoring cannot be carried out. This situation is also called RAIM hole. The second is the geometric distribution factor. Although the number of satellites meets the basic requirements of RAIM at some time and space points, the geometric layout of the satellites may cause failures on some satellites to be undetectable during integrity monitoring, and the result cannot guarantee the missed detection rate. . Therefore, overall, the RAIM method is still not suitable for integrity monitoring. the

In order to make the satellite navigation LAAS system achieve the performance of Class I precision approach, the Federal Aviation Administration (Federal Aviation Administration; hereinafter referred to as FAA) combined it with the WAAS system and proposed a Local Airport Monitoring System (Local Airport Monitoring System). Monitor (hereinafter referred to as LAM), which improves the positioning accuracy and various performances of satellite navigation, and at the same time eliminates the impact of ionospheric storms on the system. However, most of the integrity algorithms of the LAM system in the prior art need to be completed by the airborne user itself, which increases the burden on the user and reduces the real-time performance. the

Contents of the invention

The embodiment of the present invention provides a local airport monitoring method, device and system to solve the problem that most of the integrity algorithms of the LAM system in the prior art need to be completed by the airborne user itself, which increases the burden on the user and reduces the practicality To improve the performance of the local airport monitoring method and system. the

The embodiment of the present invention provides a local airport monitoring method, including:

Obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, and use the augmentation information broadcast by the wide area augmentation system, the carrier phase observation value and the tropospheric error model to analyze the pseudorange information in the satellite data Perform correction to obtain the pseudorange correction value of each satellite corresponding to each receiver, and the receiver information includes the satellite elevation value of the visible satellite corresponding to the receiver, the real distance between the receiver and the visible satellite, and each The number of satellites visible to the receiver;

Optionally one receiver is a pseudo-airborne user, and according to the receiver information of the pseudo-airborne user and the continuity requirement value preset by the airborne user, the conversion matrix from the pseudo-range domain to the positioning domain is used to calculate the described The pseudo-range correction value positioning error of the pseudo-airborne user, and extract the wide-area augmentation system information broadcast positioning error of the pseudo-airborne user from the pseudo-range correction value positioning error;

According to the receiver information of the pseudo-airborne user and the integrity risk value preset by the system, calculate the positioning error of the monitoring system of the pseudo-airborne user by using the transformation matrix from the pseudo-range domain to the positioning domain, and Calculate the ideal envelope value of the sum of the positioning error of the monitoring system and the broadcasting positioning error of the wide-area augmentation system information to obtain the ground monitoring protection level of the pseudo-airborne user, and the positioning error of the monitoring system includes Positioning errors caused by the thermal noise of the user and the multipath of the fuselage, the positioning error caused by the ionosphere above the monitoring center, and the positioning error caused by the troposphere above the monitoring center;

Comparing the ground monitoring protection level of all visible satellite combinations of the pseudo-airborne user with the preset alarm limit value of the airborne user in turn, if the ground monitoring protection level of the visible satellite combination is less than the warning limit value, then The visible satellite combination containing the largest number of satellites and the pseudorange correction value of each visible satellite in the visible satellite combination are sent to the airborne user. the

An embodiment of the present invention provides a local airport monitoring device, including:

The first calculation module is used to obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, and use the augmentation information broadcast by the wide area augmentation system, the carrier phase observation value and the tropospheric error model to calculate the The pseudo-range information in the data is corrected to obtain the pseudo-range correction value of each satellite corresponding to each receiver. The receiver information includes the satellite elevation angle value of the visible satellite corresponding to the receiver, the distance between the receiver and the visible satellite True distance and number of visible satellites per receiver;

The second calculation module is connected with the first calculation module, and is used to select a receiver as a pseudo-airborne user, according to the receiver information of the pseudo-airborne user and the preset continuity requirements of the airborne user value, using the transformation matrix from the pseudo-range domain to the positioning domain to calculate the pseudo-range correction value positioning error of the pseudo-airborne user, and extract the pseudo-airborne user’s wide area from the pseudo-range correction value positioning error Enhance system information broadcast positioning error;

The third calculation module, connected to the second calculation module, is used to convert the pseudo-range domain to the positioning domain according to the receiver information of the pseudo-airborne user and the integrity risk value preset by the system The matrix calculation obtains the monitoring system positioning error of the pseudo-airborne user, and calculates the ideal envelope value of the sum of the monitoring system positioning error and the wide-area augmentation system information broadcast positioning error to obtain the pseudo-aircraft user The ground monitoring protection level of the airborne user, the positioning error of the monitoring system includes the positioning error caused by the thermal noise of the airborne user and the multipath of the fuselage, the positioning error caused by the ionosphere above the monitoring center and the troposphere above the monitoring center The positioning error;

The judgment module is connected with the third calculation module, and is used to compare the ground monitoring protection level of all visible satellites of the false airborne user with the alarm limit preset by the airborne user in turn, if the visible satellite If the ground monitoring protection level of the combination is less than the alarm limit, the visible satellite combination containing the largest number of satellites and the pseudorange correction value of each visible satellite in the visible satellite combination are sent to the airborne user. the

An embodiment of the present invention provides a local airport monitoring system, including:

A plurality of receivers are used to receive satellite data sent by navigation satellites, perform analog-to-digital conversion on the satellite data, and send the converted satellite data and its own receiver information to the monitoring center. The machine information includes the satellite elevation value of the visible satellite corresponding to the receiver, the real distance between the receiver and the visible satellite, and the number of visible satellites of each receiver;

A monitoring center, connected with the receiver, is used to calculate the pseudo-range correction value of each satellite corresponding to the receiver according to the received satellite data, and calculate the pseudo-range correction value of the airborne user according to the receiver information. The error caused by the distance correction value and the error caused by the monitoring system are detected, and the ground monitoring protection level of the monitoring center is calculated, and by comparing the ground monitoring protection level with the user's preset alarm limit, the An available satellite combination, sending the available satellite combination and the pseudorange correction value of each visible satellite in the satellite combination to the airborne user,

The monitoring center includes: a first calculation module, which is used to obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, and use the enhanced information broadcast by the wide area augmentation system, the carrier phase observation value and the tropospheric The error model corrects the pseudorange information in the satellite data to obtain the pseudorange correction value of each satellite corresponding to each receiver, and the receiver information includes the satellite elevation angle value of the visible satellite corresponding to the receiver, the receiver The true distance between its visible satellites and the number of visible satellites per receiver;

The second calculation module is connected with the first calculation module, and is used to select a receiver as a pseudo-airborne user, according to the receiver information of the pseudo-airborne user and the preset continuity requirements of the airborne user value, using the conversion matrix from the pseudo-range domain to the positioning domain to calculate the pseudo-range correction value positioning error of the pseudo-airborne user, and extract the pseudo-airborne user’s wide area from the pseudo-range correction value positioning error Enhance system information broadcast positioning error;

The third calculation module is connected with the second calculation module, and is used to utilize the relationship between the pseudo-range domain and the positioning domain according to the receiver information of the pseudo-airborne user and the integrity risk value preset by the system The conversion matrix is calculated to obtain the monitoring system positioning error of the pseudo-airborne user, and the sum of the monitoring system positioning error and the wide-area augmentation system information broadcast positioning error is calculated for an ideal envelope value, and the pseudo-aircraft user is obtained The ground monitoring protection level of the airborne user, the positioning error of the monitoring system includes the positioning error caused by the thermal noise of the airborne user and the multipath of the fuselage, the positioning error caused by the ionosphere above the monitoring center and the troposphere above the monitoring center The positioning error;

The judgment module is connected with the third calculation module, and is used to compare the ground monitoring protection level of all visible satellites of the false airborne user with the alarm limit preset by the airborne user in turn, if the visible satellite If the combined ground monitoring protection level is less than the alarm limit, the visible satellite combination with the largest number of satellites and the pseudorange correction value of each visible satellite in the visible satellite combination will be sent to the airborne user;

An airborne user, connected to the monitoring center, is used to calculate the position of the airborne user according to the visible satellite combination and the pseudorange correction value of the visible satellite combination sent by the monitoring center. the

The local airport monitoring method, device and system of the embodiments of the present invention detect the error caused by the pseudo-range correction value and the error caused by the monitoring system for the airborne user at the monitoring terminal on the ground, and obtain the ground monitoring and protection based on the definition Based on the concept of the protection level, the calculation of the protection level of the airborne user itself is transferred to the calculation of the ground monitoring protection level by the ground monitoring center, so that the best visible satellite combination for the airborne user is completed through the detection of the protection level of the ground detection center. Compared with the method in which airborne users select satellite subsets by themselves in the existing system, while ensuring the accuracy of the system, it also improves the robustness of the system, reduces the calculation burden of airborne users, and improves the real-time sex. the

Description of drawings

Fig. 1 is the flow chart of embodiment one of local area airport monitoring method of the present invention;

Fig. 2 is the flow chart of embodiment two of local area airport monitoring method of the present invention;

Fig. 3 is the structural representation of the embodiment of local area airport monitoring device of the present invention;

Fig. 4 is a schematic structural diagram of an embodiment of the local airport monitoring system of the present invention. the

Detailed ways

The technical solutions of the embodiments of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. the

With the vigorous development of satellite navigation, countries all over the world are building their own satellite navigation systems, such as the GPS system in the United States, the GLONASS system in Russia, and the Galileo system in Europe that is under construction. However, due to the impact of ionosphere, troposphere, multipath effect and thermal noise, as well as the satellite navigation system's own problems, such as ephemeris error, satellite clock error, etc., satellite navigation cannot meet the performance required by the system in many applications. index. For example, in the application of the precision approach system of civil aviation aircraft, not only high requirements are placed on the accuracy of satellite navigation, but also strict requirements on its integrity, continuity and availability. the

In order to solve the above problems, researchers in the field of navigation have invented many auxiliary systems to enhance satellite navigation systems. At present, typical satellite navigation enhancements include WAAS and LAAS in the United States, EGNOS in the European Union, and Multi-Functional Satellite Augmentation System (MSAS) in Japan. However, due to the integrity of the civil aviation aircraft precision approach system application, its integrity still cannot meet the performance requirements of civil aviation precision approach. Based on this, relevant researchers proposed the LAM system. However, the LAM system in the prior art lacks data verification and has poor robustness. At the same time, most of the integrity algorithms need to be completed by the airborne user itself, which increases the burden on the user and reduces the real-time performance. the

Therefore, on the basis of the LAM system, the embodiment of the present invention proposes a local area airport monitoring method, device and system. Detect and estimate the satellite positioning error of the airborne user caused by the monitoring center and the airborne user itself, and calculate the ground monitoring protection level at the ground monitoring center, and convert the calculation of the protection level of the airborne user to the ground monitoring protection level. In the calculation, the calculation burden of the airborne user is reduced, and the real-time performance is improved. the

Fig. 1 is the flow chart of embodiment one of local area airport monitoring method of the present invention, as shown in Fig. 1, this implementation local area airport monitoring method comprises:

Step 100, obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, use the augmentation information broadcasted by the wide area augmentation system, the carrier phase observation value and the tropospheric error model to correct the pseudo in the satellite data Correct the distance information to obtain the pseudo-range correction value of each satellite corresponding to each receiver;

接收机i与其可见卫星j之间的真实距离 

以及每个接收机的可见卫星数目N等，监测中心根据接收到的卫星数据计算得到每个接收机对应每颗卫星的伪距校正值。  The local area airport monitoring method of this embodiment is aimed at the monitoring center in the local area airport monitoring system based on multi-receivers, because in this embodiment, after each receiver receives satellite data from their respective visible satellites , does not calculate it, but only performs analog-to-digital conversion on it, and directly sends the satellite data after analog-to-digital conversion to the monitoring center together with the receiver information. Therefore, for the calculation of the pseudo-range correction value of the receiver It is done in the monitoring center. Among them, the satellite data received by the monitoring center includes the WAAS information broadcast by the geostationary orbit satellite (Geo-stationary Orbit; hereinafter referred to as GEO) and the navigation information broadcast by the GPS satellite, while the receiver information sent by the receiver includes the receiver i corresponding Satellite elevation angle value of visible satellite j

The true distance between receiver i and its visible satellite j

And the number N of visible satellites of each receiver, etc., the monitoring center calculates the pseudo-range correction value corresponding to each satellite of each receiver according to the received satellite data.

It should be pointed out that, since the distance between the receivers on the ground is very short, while the distance between the satellite and the earth is much farther in comparison, the distance between the receivers completely negligible. Therefore, in the embodiment of the present invention, it can be approximately considered that the number of visible satellites of each receiver is the same, and because the distance between each receiver is very short, it can also be approximately considered that the number of visible satellites of each receiver is satellite elevation angle are all equal, and both are θ ^j .

Specifically, the pseudorange correction value of the receiver includes three parts: the pseudorange correction value smoothed by the Hatch filter, the wide area augmentation system pseudorange correction value and the tropospheric pseudorange correction value. Among them, the pseudo-range correction value smoothed by Hatch filter refers to that the monitoring center extracts the pseudo-range observation value and carrier phase observation value of the positioning satellite from the received satellite data, and then uses the method of Hatch filter to use the carrier phase observation value to correct The pseudo-range observation value is smoothed to obtain the smoothed pseudo-range correction value; the wide-area augmentation system pseudo-range correction value is obtained from the WAAS broadcast information broadcast by the GEO satellite, including the fast correction value, long-term correction value and The ionospheric correction value; the tropospheric pseudorange correction value is the correction value for the tropospheric error, specifically refers to the pseudorange correction value calculated by using the tropospheric error model, and the tropospheric error model here is the Saqitamonen model. the

Step 101, choose a receiving product to be a pseudo-airborne user, calculate the pseudo-range correction value positioning error of the pseudo-airborne user, and extract the pseudo-airborne user's wide-ranging error from the pseudo-range correction value positioning error Domain enhancement system information broadcast positioning error;

In this embodiment, it is assumed that there are M receivers on the ground, and one receiver is randomly selected from the M receivers, and it is assumed to be a "pseudo-airborne user". As the name implies, this "pseudo-airborne user" is a ground monitoring One airborne user assumed in the station. Since in the civil aviation system, the distance between the ground receiver and the actual airborne user is almost negligible compared with their distance to the satellite, therefore, it can be approximately considered that the error between the two points has the characteristics of commonality, Therefore, the calculation of the protection level for the actual airborne user can be reflected in the protection level calculation for the "pseudo airborne user" randomly selected from the receiver. In the process of calculating the ground monitoring protection level of the pseudo-airborne user, not only the error caused by the pseudo-range correction value, but also the error caused by the ionosphere and troposphere of the actual airborne user by the monitoring center, can be considered. Maximize the gap between the ground monitoring protection level and the actual airborne user protection level, making the monitoring results more accurate. the

In this step, the error caused by the pseudo-range correction value of the pseudo-airborne user is mainly calculated and estimated. For the error of the pseudo-range correction value of the selected pseudo-airborne user, if the measurement error of the real position is ignored, the error mainly comes from two parts: one is the monitoring error of the receiver, which is mainly caused by the ground thermal noise and multiple The other is the error caused by the information broadcast by WAAS, which is called the wide area augmentation system information broadcast error, that is, the WAAS information broadcast error. Therefore, the monitoring center will first calculate the standard deviation σ _dPR of the error of the pseudorange correction value based on the standard deviation σ _mon and σ _MWAAS of these two parts of the error, and then use the principle of variance transfer , the continuity error amplification factor K _mt is calculated by the statistical algorithm of Gaussian distribution. The continuity error amplification factor fully considers the influence on the continuity of the system caused by the false detection of the system, and finally the error of the pseudorange correction value is obtained according to the calculation The standard deviation σ _dPR and the continuity error amplification factor K _mt are used to calculate the pseudo-range correction value positioning error of the pseudo-airborne user by using the conversion matrix from the pseudo-range domain to the positioning domain. The WAAS information broadcast positioning error of the pseudo-airborne user extracted from the positioning error of the pseudo-range correction value is a part of the ground monitoring protection level of the pseudo-airborne user.

Step 102: According to the transformation matrix from the pseudo-range domain to the positioning domain, calculate the monitoring system positioning error of the pseudo-airborne user, and calculate the sum of the monitoring system positioning error and the wide-area augmentation system information broadcast positioning error The calculation of the ideal envelope value obtains the ground monitoring protection level of the pseudo-airborne user;

Because in this embodiment, the core idea of the calculation of the protection level of ground monitoring is: the calculation of the protection level of the actual airborne user is converted to the calculation of the protection level of the ground monitoring center, that is, converted to the calculation of the protection level of the pseudo-airborne user Therefore, in the calculation of the value of the protection level, the impact of various errors on the ground monitoring protection level has to be taken into account, specifically, the following four parts are included: Information broadcast by WAAS Errors caused by airborne receiver thermal noise and airframe multipath, ionospheric errors from the lateral component over the monitoring center on the ground, and tropospheric errors from the vertical component from ground monitoring stations. Among them, the error caused by the information broadcast by WAAS, that is, the broadcast error of WAAS information can be obtained by subtracting the pseudorange correction value positioning error calculated in step 101 and the receiver monitoring positioning error, so in this step, it is mainly calculated The positioning errors of the other three parts, in the embodiment of the present invention, since these three parts of errors are caused by various factors of the monitoring system, such as the factors of the airborne user itself or the factors of the monitoring center, these three parts are collectively referred to as The positioning error is the monitoring system positioning error. the

For the calculation of the positioning error value of the monitoring system, firstly, the monitoring center will calculate the pseudorange domain standard deviation of each error in the monitoring system error according to the receiver information, and then use the conversion matrix from the pseudorange domain to the positioning domain to convert them respectively Convert it into the standard deviation of the positioning domain in the vertical direction, and use the principle of variance transfer to calculate the positioning standard deviation of the monitoring system error; then, the monitoring center will calculate the integrity risk value through the Gaussian distribution statistical algorithm according to the system’s preset integrity risk value. The performance error amplification factor K _bnd , compared with the integrity risk value preset by the existing system, in this embodiment, the integrity error amplification factor also considers the impact of the WAAS failure on the entire LAM system; finally, the monitoring center according to Calculate the positioning standard deviation of the monitoring system error and the integrity error amplification factor K _bnd , and use the transformation matrix from the pseudo-range domain to the positioning domain to calculate the positioning error of the monitoring system for the pseudo-airborne user. The positioning error of the monitoring system is the airborne user Another part of the ground monitoring protection level.

In this embodiment, after the monitoring center obtains the WAAS information broadcast positioning error and the monitoring system positioning error respectively through calculation, the sum of the two calculated by the user is the actual total positioning error of the pseudo-airborne user, and on this basis Above, the actual total positioning error is further calculated by the ideal envelope value, and finally the ground monitoring protection level of the pseudo-airborne user is obtained. Through the detection of the ground monitoring protection level, it can be judged in the ground monitoring center. Best combination of satellites available. the

Step 103, comparing the ground monitoring protection level of all visible satellite combinations of the pseudo-airborne user with the preset alarm limit value of the airborne user, obtaining the best available satellite combination according to the comparison result, and using the best available satellite The combination and the pseudorange corrections for each visible satellite in the combination of available satellites are sent to the airborne user. the

Specifically, the monitoring center divides all visible satellites of pseudo-airborne users into multiple satellite subsets by round-robin removal method, and first forms a set of all visible satellites of pseudo-airborne users, which is called the first-level satellite subset , to determine whether the number of visible satellites in the first-level satellite subset is equal to 4, and if it is equal to 4, stop dividing the subset; otherwise, remove one satellite from the set according to the preset order, and generate the second-level The satellite subset, the preset order referred to here can be the data of the satellites arranged in ascending order according to the elevation angle of the satellites, and the meaning of removing separately means that only one of the satellites is removed at a time, rather than sequentially removed, that is, it is assumed that all visible The number of satellites is N. When the first satellite is removed, there are N-1 satellites left in the satellite combination. When the second satellite is removed, the removed first satellite is added to the satellite combination, and N is still left in the satellite combination. -1, at this time, judge whether the number of visible satellites in the second-level satellite subset is equal to 4, if the number of visible satellites contained in the second-level satellite subset is equal to 4, then stop dividing the subsets, if the first When the number of visible satellites contained in the second-level satellite subset is greater than 4, continue to divide the satellite subset according to this method to generate a new N-th-level satellite subset until the number of visible satellites in the N-th-level satellite subset is equal to 4 . Assuming that the number of final satellite subsets obtained by dividing by the round robin removal method is B, B can be obtained by the formula: $B=C_N^N+C_N^{N-1}+...+C_N^5+C_N^4$ Calculated, where N is the number of all visible satellites of the pseudo-airborne user.

After dividing the subsets of visible satellites, the monitoring center will calculate the ground monitoring protection levels of all satellite subsets of pseudo-airborne users, and compare the ground monitoring protection levels of the satellite subsets with the user-preset alarm limit in turn. Comparison, if the ground monitoring protection level of a subset is less than the alarm limit value, then the subset containing the visible satellites with the largest number of satellites and the pseudorange correction value of each visible satellite in the subset are sent to the airborne user, the The subset containing the visible satellites with the largest number of satellites is the best combination of visible satellites. the

This embodiment provides a local airport monitoring method, by detecting the error caused by the pseudo-range correction value and the error caused by the monitoring system for the airborne user at the monitoring end on the ground, and defining the protection level of the ground monitoring accordingly. concept, the calculation of the protection level of the airborne user itself is transferred to the calculation of the ground monitoring protection level by the ground monitoring center, so that the selection of the best visible satellite combination for the airborne user is completed through the detection of the protection level of the ground detection center , compared with the method in which the airborne user selects satellite subsets by himself in the existing system, while ensuring the system accuracy, it also improves the robustness of the system, reduces the calculation burden of the airborne user, and improves the real-time performance. the

Fig. 2 is the flow chart of embodiment two of local area airport monitoring method of the present invention, as shown in Fig. 2, this implementation local area airport monitoring method comprises:

Step 200, obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, and calculate the pseudorange correction value PR _i ^j of each visible satellite corresponding to each receiver according to the satellite data;

The operation of step 200 is the same as that of step 100 in the first embodiment, the satellite data sent by each receiver is received, and the pseudorange correction value of the receiver is obtained. Specifically, for the j-th visible satellite of the i-th receiver, its pseudo-range correction value can be expressed by the following expression:

${\mathrm{<span\; class="notranslate">\; PR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; Si</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; PRC</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; TC</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, P _Si ^j is the pseudorange correction value smoothed by Hatch filter, PRC _i ^j is the pseudorange correction value obtained from WAAS broadcast information, and TC _i ^j is the tropospheric pseudorange correction value. Specifically, the monitoring center first extracts the pseudo-range observation value P and carrier phase observation value φ of the positioning satellite from the received satellite data, and then uses the Hatch filter method to smooth the pseudo-range observation value P with the carrier phase observation value φ , to obtain the pseudorange correction value smoothed by the Hatch filter, the calculation formula of the Hatch filter is shown in formula (2):

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; Si</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; Si</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula, l represents the epoch, τ _s is the filtering time constant, T _S is the measurement interval, and N _s is the filtering length: $N_{\mathrm{the\; s}}=\frac{{\mathrm{\&tau;}}_{\mathrm{the\; s}}}{T_{\mathrm{the\; s}}},$ P(l) is the pseudorange measurement value of the lth epoch, φ(l) is the carrier phase measurement value of the lth epoch, P _S (l-1) is the Hatch filter smoothing value of the l-1th epoch Pseudorange correction value.

After the pseudo-range observation value P is smoothed by Hatch filtering, the purpose of removing noise will be achieved. At this time, the pseudo-range value obtained from the WAAS broadcast information is corrected to obtain the WAAS pseudo-range correction value PRC _i ^j , the WAAS pseudo-range The correction value also includes three parts: WAAS fast correction value FC _i ^j , WAAS long-term correction value LTC _i ^j and WAAS ionospheric correction value IC _i ^j , the value of each part can be given according to the WAAS message type The specific information is calculated. The calculation expression of PRC _i ^j is as follows:

${\mathrm{<span\; class="notranslate">\; PRC</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; FC</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; LTC</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; IC</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Finally, the tropospheric pseudorange correction value TC _i ^j is calculated. In this embodiment, in the process of correcting the pseudorange of the satellite data, the monitoring center not only uses the information broadcast by WAAS, but also uses the Hatch filter to process the code pseudorange, and at the same time The tropospheric error is also corrected using the tropospheric error model, specifically referring to the correction of the pseudorange information using the Sastamonen model. The calculation formula of TC _i ^j is:

${\mathrm{<span\; class="notranslate">\; TC</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\frac{{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 6</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 0.002</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;h</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Among them, N _r is the tropospheric refraction coefficient, _h0 is the tropospheric height, which can be extracted from the navigation information included in the satellite data, _θi ^j is the satellite elevation angle, which is the data contained in the receiver information sent by the receiver, and Δh is The height of the aircraft (that is, the airborne user) from the monitoring center on the ground can be obtained according to actual measurement.

Step 201, correcting the distance error between the receiver and the satellite for the pseudo-range correction value PR _i ^j to obtain a new pseudo-range correction value dPR _i ^j ;

Since the position of each receiver is known, the real distance R _i ⁱ between each receiver and the satellite can be obtained by calculation in the receiver, and the receiver sends it to the monitoring center, and the monitoring center uses the real The distance R _i ⁱ and the pseudo-range correction value PR _i ^j of the receiver calculated in step 200 can further correct the distance error between the receiver and the satellite for the pseudo-range correction value of the receiver, and obtain a new pseudo-range correction value dPR _i ^j , the calculation formula of dPR _i ^j is:

${\mathrm{<span\; class="notranslate">\; QUR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; PR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Step 202, choose a receiver as a pseudo-airborne user, and calculate the pseudo-range correction value positioning error of the pseudo-airborne user. The specific calculation process includes:

Step 2021, choose a receiver as a pseudo-airborne user, and calculate the error standard deviation σ _dPR of the pseudo-range correction value of the pseudo-airborne user;

In this embodiment, the error of the pseudo-range correction value of the pseudo-airborne user mainly comes from two parts: the error caused by the monitoring error of the receiver and the information broadcast by WAAS, which are respectively called the receiver monitoring error and the WAAS information broadcast error , and it is assumed that the errors of the two parts are subject to a Gaussian distribution with a mean value of 0. Therefore, the standard deviation of the two parts of the errors needs to be calculated first. the

For the receiver monitoring error standard deviation σ _mon , it can be calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; mon</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\sqrt{\frac{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Among them, a ₀ , a ₁ , and θ ₀ are determined by the performance level of the receiver. For details, please refer to the standard RTCA DO-245A of the Radio Technical Committee for Aviation, θ ^j is the satellite elevation angle value, and M is the number of receivers.

For the standard deviation of WAAS broadcast information error, it can be calculated by the following calculation formula:

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; MWAAS</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.26</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; OF</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.26</span>}<span\; class="notranslate">\; \&CenterDot;</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span>}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Among them, OF is the ionospheric tilt factor, R _e is the radius of the earth, and h _I is the ionospheric height.

The error standard deviation _σdPR of the pseudorange correction value can be obtained according to the principle of variance transfer:

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; QUR</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\sqrt{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; mon</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; MWAAS</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Step 2022, calculating the continuity error amplification factor K _mt according to the continuity demand value preset by the airborne user;

In order to ensure the continuity of the system, the continuity error amplification factor in the error of the pseudorange correction value is related to the continuity of the system. The loss of continuity of the system generally includes two aspects: either because of real system failures, such as satellite failures or ground station failures; or because of false detection of failures. According to the allocation of half of the continuity requirement preset by the user, it is assumed that the continuity requirement preset by the user is P _r (continuity):

P _{false detection} = Pr (continuous) / 2 (8)

For M receivers, the single-receiver fault protection level corresponding to any receiver failure may cause loss of continuity. Therefore, conservatively considered, all single-receiver fault protection levels are independent, so there is no fault false detection The probability can be determined by dividing the overall continuity requirement by M, i.e.

P _FD/M = P _{false detection} /M (9)

The above probability is for a receiver, assuming that the number of satellites visible to this receiver is N, then for the measured value corresponding to each satellite, the false detection probability is:

P _FFD =P _FFD/M /N (10)

So the final continuity error amplification factor is:

K _mt = Q ⁻¹ (P _FFD /2) (11)

in, $Q\left(x\right)=\frac{1}{\sqrt{2\mathrm{\&pi;}}}{\&Integral;}_x^{\&infin;}{e}^{-\frac{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2}{2}}\mathrm{dt}.$

Step 2023, according to the pseudorange correction value error standard deviation and the continuity error amplification factor, calculate and obtain the pseudorange correction value positioning error E _k ;

In order to obtain higher monitoring efficiency, the monitoring center usually uses the conversion matrix S from the pseudo-range domain of the positioning satellite to the positioning domain to convert the pseudo-range error into a positioning error. The specific calculation method of the conversion matrix S is shown in the following formula:

S＝(H ^T W ^-1 H) ^-1 H ^T W ^-1 (12)

Among them, H represents the geometric matrix of the positioning satellite, which is determined by the position of the satellite and the receiver, and W is the weight, which is a diagonal matrix composed of the standard deviation of the receiver of the positioning satellite. The detailed calculation formulas for these two parameters Reference can be made to the standard RTCA DO-245 of the Radio Technical Commission for Aeronautics. the

Moreover, the transformation matrix S is four rows (representing x, y, z, t) N _k columns, N _k is the number of visible satellites corresponding to the pseudo airborne user, and S _{j, vert} represents the zth row of the matrix. Since in civil aviation applications, the requirements in the vertical direction are much more stringent than those in the horizontal direction, when converting the error from the pseudo-range domain to the positioning domain, in this embodiment, only the vertical direction is considered, and finally we get The threshold value of the positioning error of the pseudorange correction value can be calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; TE</span>}}_{\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; mt</span>}}\sqrt{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="vert"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">vert</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; QUR</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 13</span>}<span\; class="notranslate">\; )</span>$

Through the above steps, the monitoring center detects and calculates the error caused by the pseudo-range correction value of the pseudo-airborne user’s receiver, and obtains the threshold value of the pseudo-range correction value positioning error of the pseudo-airborne user, that is, the maximum error. the

Step 2024, extracting the broadcast positioning error E _WAAS,k of the wide area augmentation system information of the pseudo-airborne user from the positioning error of the pseudo-range correction value;

Since the positioning error of the pseudo-range correction value is composed of two parts: the receiver monitoring positioning error E _mon,k and the WAAS information broadcast positioning error E _WAAS,k , the pseudo-airborne user is extracted from the pseudo-range correction value positioning error E _k When the broadcast error E _WAAS,k of the wide-area augmentation system information of , it is necessary to subtract the receiver monitoring positioning error E _mon, k from the pseudo-range correction value positioning error E _k .

Step 203, calculating the monitoring system positioning error of the pseudo airborne user, the specific calculation process includes:

Step 2031, calculating the error standard deviation of each monitoring system of the pseudo airborne user;

For actual airborne users, the total error that usually needs to be considered mainly includes four parts: the error caused by the information broadcast by WAAS, the thermal noise of the airborne receiver and the error caused by the multipath of the fuselage, and the error caused by the ground monitoring center. Ionospheric errors due to lateral components, and tropospheric errors due to vertical components from ground monitoring centers. Therefore, in this embodiment, in the calculation of the ground monitoring positioning error of the pseudo-airborne user, the positioning error caused by these four aspects is mainly considered. In this embodiment, due to the particularity of the civil aviation application mentioned above, the requirements in the vertical direction are much more stringent than those in the horizontal direction. Therefore, only the situation in the vertical direction is considered here, and the resulting pseudo-airborne The user's total error expression is:

E _{total, vert, k} = E _{MWAAS, vert, k} + E _{air, vert, k} + E _{iono, vert, k} + E _{trop, vert, k} (14)

Among them, it is assumed that:

E _{other, vert, k} = E _{air, vert, k} + E _{iono, vert, k} + E _{trop, vert, k} (15)

And the error E _{MWAAS, vert, k} caused by the information broadcast by WAAS can be calculated in step 204, so:

E _{total, vert, k} = E _{vert, k} - E _{mon, vert, k} + E _{other, vert, k} (16)

So far, the calculation of the total error of the pseudo-airborne user has become the calculation of the above three parts, wherein the first part of the pseudo-range correction value positioning error E _vert,k has been calculated in step 203, and the second part of the receiver The monitoring of the error E _{mon, vert, k} obeys the Gaussian distribution whose mean value is 0 and the standard deviation is σ _mon , and the standard deviation σ _mon has been calculated in formula (5), so in this step, it should be Computes the standard deviation of the inclusive three-part error in E _{other, vert, k} .

Specifically, for the thermal noise of the airborne user itself and the error caused by the multipath of the airframe and the standard deviation of the airframe multipath error σair _,vert,j and the ionospheric error caused by the lateral component of the ground monitoring station The standard deviation of the ionospheric error σ _{iono, vert, j} , its detailed calculation formula can refer to the standard RTCA DO-245 of the Aeronautical Radio Technical Committee, as follows:

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; air</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\sqrt{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; air</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="noise"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">noise</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; air</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="multipath"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">multipath</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0.11</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.13</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\frac{{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0.13</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.53</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}}{\mathrm{<span\; class="notranslate">\; 10</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 17</span>}<span\; class="notranslate">\; )</span>$

σ _iono,vert,j = 0.106×OF(θ ^j ) (18)

Among them, OF is the ionospheric tilt factor, and θ ^j is the satellite elevation angle value.

For the standard deviation of the tropospheric error σ _tropo,vert,j caused by the vertical component of the surface monitoring station, due to the value of σ tropo,vert,j relative to σ _air,vert,j and σ _{iono,vert ,j} is small, so approximately:

σ _{tropo, vert, j} = 0 (19)

Step 2032, calculating the integrity error amplification factor K _bnd according to the integrity risk value preset by the system;

When calculating the positioning error of the monitoring system of the pseudo-airborne user, the error is approximately considered as an ideal value, that is, the error E _MWAAS,vert,k caused by the information broadcast by WAAS, the thermal noise of the airborne receiver and the airframe The error E _air,vert,k due to multipath, the ionospheric error E _iono,vert,k due to the lateral component from the ground monitoring station, and the tropospheric error E _air,vert,k due to the vertical component from the ground monitoring station They are all calculated under the assumption of Gaussian distribution. Therefore, in the calculation process of the monitoring system positioning error, the integrity risk value assigned by the LAM system for the vertical protection level must be taken into account. The risk value is specifically determined by the integrity error factor K _bnd is reflected, specifically, the calculation formula of K _bnd is:

K _bnd = Q ^-1 (P _integrity ) (20)

in, $Q\left(x\right)=\frac{1}{\sqrt{2\mathrm{\&pi;}}}{\&Integral;}_x^{\&infin;}{e}^{-\frac{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2}{2}}\mathrm{dt},$ P _integrity represents the integrity risk value assigned by the multi-receiver LAM system for the vertical protection level, specifically 8.5e-8, compared with the P _integrity of 2.5e-8 in the existing algorithm, the value of this embodiment The impact of WAAS failure on the LAM system is further considered.

Step 2033, according to the above integrity error amplification factor and each monitoring system error standard deviation, calculate the positioning error of the monitoring system;

In this embodiment, in order to obtain higher monitoring efficiency, the standard deviation of the monitoring system error can be obtained by transforming the standard deviation of the pseudo-range domain through the conversion matrix S from the pseudo-range domain to the positioning domain:

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; air</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\sqrt{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="vert"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">vert</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; air</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">j</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; iono</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\sqrt{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="vert"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">vert</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; iono</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; twenty\; one</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; tropo</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\sqrt{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="vert"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">vert</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; tropo</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">j</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

Define σ _{other, vert, k} as the sum of the above three standard deviations, which can be obtained through the principle of variance transfer:

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; other</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\sqrt{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; air</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="k"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">k</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; iono</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="k"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">k</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; tropo</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; twenty\; two</span>}<span\; class="notranslate">\; )</span>$

In addition, since the calculation of the total positioning error of pseudo-airborne users also includes the receiver monitoring positioning error E _mon,vert,k , and the receiver monitoring positioning error E _mon,vert,k is related to the monitoring system positioning error E _{other, vert, and k} all obey the Gaussian distribution with a mean value of 0. Therefore, in an ideal situation, the envelope value of the two can be calculated. Specifically, the above formula (16) can be converted into:

VPL _{ideal, k} = |E _{vert, k} |+K _bnd σ _{mon+other, vert, k} (23)

Among them, taking the absolute value of the pseudorange correction value positioning error E _{vert, k} is also to obtain the maximum value under ideal conditions, and, according to the principle of variance transfer, σ _{mon+other, vert, k} can be calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; mon</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; other</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\sqrt{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; mon</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="k"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">k</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; other</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; twenty\; four</span>}<span\; class="notranslate">\; )</span>$

Step 2034, calculating the ground monitoring protection level VPL _mon,k of the pseudo-airborne user;

Since the absolute value of the pseudorange correction value positioning error E _vert,k in formula (23) is the threshold value TE _vert,k of the pseudo-range correction value positioning error of the pseudo-airborne user obtained by formula (13), Finally, the ground monitoring protection level of pseudo-airborne users can be obtained as:

${\mathrm{<span\; class="notranslate">\; VPL</span>}}_{\mathrm{<span\; class="notranslate">\; mon</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; mt</span>}}\sqrt{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="vert"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">vert</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; QUR</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; bnd</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; mon</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; other</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 25</span>}<span\; class="notranslate">\; )</span>$

Step 204, comparing the ground monitoring protection levels of all visible satellite combinations of the pseudo-airborne user with the preset alarm limit value of the airborne user in turn, and if the ground monitoring protection level of the visible satellite combination is less than the alarm limit value, execute Step 205, if the ground monitoring protection levels of all visible satellite combinations are greater than the alarm limit, then execute 206;

Specifically, in this step, all visible satellites of pseudo-airborne users will first be divided into visible satellite subsets by round robin removal method, and then the ground monitoring protection level of each subset will be calculated for each visible satellite subset , the specific process of dividing visible satellite subsets has been described in detail in Embodiment 1, and will not be repeated here. For each subset of visible satellites of pseudo-airborne users, the value of its ground monitoring protection level may be greater than or less than the alarm limit preset by the airborne user. , representing that the visible satellite combination of this subset is available to the airborne user, and when its ground monitoring protection level is greater than the alarm limit preset by the airborne user, it represents that the visible satellite combination of this subset is not available to the airborne user. is not available to the user, the subset should be discarded. the

Step 205, sending the visible satellite combination containing the largest number of satellites and the pseudorange correction value of each visible satellite in the visible satellite combination to the airborne user;

If the value of the ground monitoring protection level of the pseudo-airborne user is greater than the warning limit of the airborne user, the visible satellite combination representing the subset is available to the airborne user, and the visible satellite combination should be sent to the airborne user. However, in general, for a combination with more satellites, the monitoring protection level is smaller. For airborne users, the smaller the monitoring protection level, the smaller the error of the airborne user. Therefore, the airborne user The combination of visible satellites with the largest number of satellites should be selected. In this embodiment, the monitoring center selects the combination of visible satellites, and directly according to the comparison result of the ground monitoring protection level and the warning limit value, the visible satellite combination with the largest number of satellites and each visible satellite combination in the visible satellite combination are selected. The pseudorange correction value of the satellite is directly sent to the airborne user, which reduces the calculation burden of the airborne user. the

Step 206, sending warning information to the airborne user indicating that the satellite navigation system is unavailable for the airborne user. the

If the ground monitoring protection level calculated by all visible satellite combinations of the pseudo-airborne user is greater than the alarm limit, it means that all satellite combinations of the airborne user are unavailable, and the monitoring center will send a warning message to the airborne user. The warning information indicates that the current satellite navigation system of the airborne user is unavailable. the

This embodiment provides a local area airport monitoring method. On the basis of multiple receivers, the error caused by the pseudo-range correction value and the error caused by the monitoring system are detected for the airborne user at the monitoring end on the ground, and the error is detected according to the This definition obtains the concept of ground monitoring protection level, and converts the calculation of the protection level of the airborne user itself into the calculation of the ground monitoring protection level by the ground monitoring center, so that the airborne monitoring is completed by detecting the protection level of the ground detection station. The selection of the user's best visible satellite combination, compared with the method of satellite subset selection by the airborne user in the existing system, not only ensures the accuracy of the system, but also improves the robustness of the system and reduces the burden of the airborne user. The calculation burden improves the real-time performance. Further, in the calculation process of the ground monitoring protection level in this embodiment, the influence of tropospheric errors, as well as the continuity loss and WAAS caused by integrity monitoring errors are also fully considered. The impact of faults on the LAM system makes the calculation of this protection level more accurate. the

Those of ordinary skill in the art can understand that all or part of the steps for realizing the above-mentioned method embodiments can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the It includes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other various media that can store program codes. the

Fig. 3 is the structural representation of the embodiment of the local area airport monitoring device of the present invention, as shown in Fig. 3, the local area airport monitoring device of the present invention comprises:

The first calculation module 11 is used to obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, and use the augmentation information broadcast by the wide area augmentation system, the carrier phase observation value and the tropospheric error model to calculate the The pseudo-range information in the satellite data is corrected to obtain the pseudo-range correction value of each satellite corresponding to each receiver. The receiver information includes the satellite elevation value of the visible satellite corresponding to the receiver, the distance between the receiver and its visible satellite and the number of visible satellites per receiver;

The second calculation module 12 is connected with the first calculation module 11, and is used to select a receiver as a pseudo-airborne user, and according to the receiver information of the pseudo-airborne user and the serial number preset by the airborne user The pseudo-range correction value positioning error of the pseudo-airborne user is calculated by using the conversion matrix from the pseudo-range domain to the positioning domain, and the pseudo-airborne user’s location error is extracted from the pseudo-range correction value positioning error Wide area enhanced system information broadcast positioning error;

The third calculation module 13 is connected with the second calculation module 12, and is used for using the pseudo-range domain to the positioning domain according to the receiver information of the pseudo-airborne user and the integrity risk value preset by the system The transformation matrix is calculated to obtain the monitoring system positioning error of the pseudo-airborne user, and the sum of the monitoring system positioning error and the wide-area augmentation system information broadcast error is calculated for the ideal envelope value, and the pseudo-aircraft user is obtained The ground monitoring protection level of the airborne user, the positioning error of the monitoring system includes the positioning error caused by the thermal noise of the airborne user and the multipath of the fuselage, the positioning error caused by the ionosphere above the monitoring center and the troposphere above the monitoring center The positioning error;

Judgment module 14, connected with the third calculation module 13, is used to compare the ground monitoring protection level of all visible satellite combinations of the pseudo-airborne user with the alarm limit value preset by the airborne user in turn, if the If the ground monitoring protection level of the visible satellite combination is less than the alarm limit, the visible satellite combination containing the largest number of satellites and the pseudorange correction value of each visible satellite in the visible satellite combination are sent to the airborne user. the

Specifically, the local airport monitoring device is set at the monitoring center of the local airport monitoring system, and its specific monitoring process has been described in detail in the above-mentioned embodiments of the local airport monitoring method, and will not be repeated here. the

The embodiment of the present invention provides a local airport monitoring device, which detects the error caused by the pseudo-range correction value and the error caused by the monitoring system for the airborne user at the monitoring end on the ground, and obtains the ground monitoring protection level based on this definition concept, the calculation of the protection level of the airborne user itself is transferred to the calculation of the ground monitoring protection level by the monitoring center on the ground, so that the selection of the best visible satellite combination for the airborne user is completed through the detection of the protection level of the ground detection station , compared with the method in which the airborne user selects satellite subsets by himself in the existing system, while ensuring the system accuracy, it also improves the robustness of the system, reduces the calculation burden of the airborne user, and improves the real-time performance. the

Fig. 4 is the structural representation of the embodiment of local area airport monitoring system of the present invention, as shown in Fig. 4, local area airport monitoring system of the present invention comprises:

A plurality of receivers 1 are used to receive satellite data sent by navigation satellites, perform analog-to-digital conversion on the satellite data, and send the satellite data after digital-to-analog conversion and its own receiver information to the monitoring center, the The receiver information includes the satellite elevation angle value of the visible satellite corresponding to the receiver, the real distance between the receiver and the visible satellite, and the number of visible satellites for each receiver;

A monitoring center 2, connected with the receiver 1, is used to calculate the pseudorange correction value of each satellite corresponding to the receiver according to the received satellite data, and to provide airborne user information based on the receiver information. The error caused by the pseudo-range correction value and the error caused by the monitoring system are detected, and the ground monitoring protection level of the monitoring center is calculated, and the comparison result is obtained by comparing the ground monitoring protection level with the user's preset alarm limit. , obtain the available satellite combination, and send the available satellite combination and the pseudorange correction value of each visible satellite in the satellite combination to the airborne user;

Specifically, the monitoring center can be equipped with the local airport monitoring device in the above embodiment, and all the specific calculation process and monitoring operations of the satellite data in the monitoring center can be realized by the local airport monitoring device. The specific components and functions of the domain airport monitoring device have been described in detail in the above embodiments, and will not be described here. the

An airborne user 3, connected to the monitoring center 2, is used to calculate the position of the airborne user according to the visible satellite combination and the pseudorange correction value of the visible satellite combination sent by the monitoring center. the

Specifically, during the approach process, it is approximately considered that the visible satellites of the airborne user and the ground monitoring station are the same. Since the position of the airborne user is higher, the number of visible satellites of the airborne user may be more than the number of visible satellites of the ground monitoring station. When the redundant satellites are "abandoned". The airborne user uses the subset of the "best" satellite combination sent by the ground monitoring station and the pseudo-range correction value of each satellite to calculate the protection level, and obtain the position of the airborne user according to the calculation result. For the calculation of the protection level of the airborne user, it can be calculated according to the pseudo-range correction value of the visible satellite provided by the monitoring center, and the pseudo-range correction value is represented by a Gaussian distribution with zero mean value, and the positioning error in the vertical direction thus obtained is The protection level is calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; VPL</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; ffmd</span>}}\sqrt{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="vert"\; filenames="H2009100885127E00032.png"\; state="\{\{state\}\}">vert</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; QUR</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; other</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; vert</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 26</span>}<span\; class="notranslate">\; )</span>$

Among them, K _ffmd is the no-fault missed detection factor, which takes a fixed value of 5.847.

The embodiment of the present invention provides a local airport monitoring system, which detects the error caused by the pseudo-range correction value and the error caused by the monitoring system for the airborne user at the monitoring center on the ground, and obtains the ground monitoring protection level based on this definition concept, the calculation of the protection level of the airborne user itself is transferred to the calculation of the ground monitoring protection level by the monitoring center on the ground, so that the selection of the best visible satellite combination for the airborne user is completed through the detection of the protection level of the ground detection station , compared with the method in which the airborne user selects satellite subsets by himself in the existing system, while ensuring the system accuracy, it also improves the robustness of the system, reduces the calculation burden of the airborne user, and improves the real-time performance. the

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention. the

Claims (9)

1. A local area airport monitoring method is characterized in that, comprising: Obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, use the augmentation information broadcast by the wide area augmentation system, the carrier phase observation value and the tropospheric error model to carry out the pseudo-range information in the satellite data Correction, to obtain the pseudorange correction value of each satellite corresponding to each receiver, the receiver information includes the satellite elevation angle value of the visible satellite corresponding to the receiver, the real distance between the receiver and its visible satellite, and each receiver the number of visible satellites; Optionally one receiver is a pseudo-airborne user, and according to the receiver information of the pseudo-airborne user and the continuity requirement value preset by the airborne user, the conversion matrix from the pseudo-range domain to the positioning domain is used to calculate the described The pseudo-range correction value positioning error of the pseudo-airborne user, and the wide-area augmentation system information broadcast positioning error of the pseudo-airborne user is extracted from the pseudo-range correction value positioning error; According to the receiver information of the pseudo-airborne user and the integrity risk value preset by the system, calculate the positioning error of the monitoring system of the pseudo-airborne user by using the transformation matrix from the pseudo-range domain to the positioning domain, and Calculate the ideal envelope value of the sum of the positioning error of the monitoring system and the broadcasting positioning error of the wide-area augmentation system information to obtain the ground monitoring protection level of the pseudo-airborne user, and the positioning error of the monitoring system includes Positioning errors caused by the thermal noise of the user and the multipath of the fuselage, the positioning error caused by the ionosphere above the monitoring center, and the positioning error caused by the troposphere above the monitoring center; Comparing the ground monitoring protection level of all visible satellite combinations of the pseudo-airborne user with the preset alarm limit value of the airborne user in turn, if the ground monitoring protection level of the visible satellite combination is less than the warning limit value, then The visible satellite combination containing the largest number of satellites and the pseudorange correction value of each visible satellite in the visible satellite combination are sent to the airborne user. 2. The local area airport monitoring method according to claim 1, characterized in that, according to the receiver information of the pseudo-airborne user and the preset continuity requirement value of the airborne user, the pseudo-range field is used The calculation of the conversion matrix to the positioning domain to obtain the pseudo-range correction value positioning error of the pseudo-airborne user includes: According to the receiver information, the monitoring error standard deviation of the pseudo-airborne user and the wide-area enhancement system broadcast information error standard deviation are obtained, and the pseudo-range correction value error standard deviation is calculated by using the variance transfer principle, and the pseudo-range correction value error is The standard deviation is the standard deviation when the error of the pseudo-range correction value of the pseudo-airborne user obeys a Gaussian distribution; According to the continuity demand value preset by the airborne user, the continuity error amplification factor is calculated through the statistical algorithm of Gaussian distribution; According to the pseudorange correction value error standard deviation and the continuity error amplification factor, the pseudorange correction value positioning error is calculated by using the conversion matrix from the pseudorange domain to the positioning domain. 3. the local area airport monitoring method according to claim 2, is characterized in that, the wide area augmentation system information broadcast positioning error of described false airborne user is extracted from described pseudo-range correction value positioning error is specifically : The pseudo-airborne user's receiver-monitored position error is subtracted from the pseudo-range correction value position error. 4. The local area airport monitoring method according to claim 3, characterized in that, according to the receiver information of the pseudo-airborne user and the integrity risk value preset by the system, the pseudo-range field is used The conversion matrix to the positioning domain is calculated to obtain the monitoring system positioning error of the pseudo-airborne user including: According to the receiver information, the thermal noise of the pseudo-airborne user, the standard deviation of the multipath error of the fuselage, the standard deviation of the ionospheric error and the standard deviation of the tropospheric error are obtained, and the standard deviation of the monitoring system error is calculated by using the principle of variance transfer. Thermal noise and fuselage multipath error standard deviation, ionospheric error standard deviation and tropospheric error standard deviation are respectively when the thermal noise of the pseudo-airborne user and fuselage multipath error, ionospheric error and tropospheric error obey the Gaussian distribution standard deviation; According to the integrity risk value preset by the system, the integrity error amplification factor is calculated through the statistical algorithm of Gaussian distribution; According to the monitoring system error standard deviation and the integrity error amplification factor, the monitoring system positioning error is calculated by using the conversion matrix from the pseudo-range domain to the positioning domain. 5. The local area airport monitoring method according to claim 1 or 4, wherein the ground monitoring protection level combined with all visible satellites of the pseudo-airborne user is sequentially matched with the preset alarm limit of the airborne user Values to compare include: Dividing all visible satellites of the pseudo airborne user into multiple satellite subsets by a round robin removal method, the number of visible satellites contained in the satellite subsets is greater than or equal to 4; Calculate the ground monitoring protection level of each satellite subset of the pseudo-airborne user, and compare the ground monitoring protection level of the satellite subset with the alarm limit value in turn. 6. the local area airport monitoring method according to claim 5, is characterized in that, described all visible satellites of described false airborne user are divided into a plurality of satellite subsets by round robin removal method and comprise: All the visible satellites of the pseudo airborne users are formed into a first-level satellite subset, and it is judged whether the number of visible satellites in the first-level satellite subset is equal to 4, if the visible satellites contained in the first-level satellite subset are When the number of satellites is equal to 4, the division of the satellite subsets is stopped, otherwise, one satellite is respectively removed from the first satellite subset according to a preset order to generate a second-level satellite subset; Judging whether the number of visible satellites in the second-level satellite subset is equal to 4, if the number of visible satellites contained in the second-level satellite subset is equal to 4, then stop dividing the satellite subsets; Continue to remove a satellite in the second-level satellite subset according to the preset order to generate the third-level satellite subset; And so on, until the number of satellites included in the Nth-level satellite subset generated by division is equal to 4. 7. the local area airport monitoring method according to claim 6, is characterized in that, described method also comprises: If the ground monitoring protection levels of all visible satellite combinations of the pseudo-airborne user are greater than the warning limit, then send warning information indicating that the satellite navigation system of the airborne user is unavailable to the airborne user. 8. A local area airport monitoring device, characterized in that it comprises: The first calculation module is used to obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, and use the augmentation information broadcast by the wide area augmentation system, the carrier phase observation value and the tropospheric error model to calculate the The pseudo-range information in the data is corrected to obtain the pseudo-range correction value of each satellite corresponding to each receiver. The receiver information includes the satellite elevation angle value of the visible satellite corresponding to the receiver, the distance between the receiver and the visible satellite True distance and number of visible satellites per receiver; The second calculation module is connected with the first calculation module, and is used to select a receiver as a pseudo-airborne user, according to the receiver information of the pseudo-airborne user and the preset continuity requirements of the airborne user value, using the transformation matrix from the pseudo-range domain to the positioning domain to calculate the pseudo-range correction value positioning error of the pseudo-airborne user, and extract the pseudo-airborne user’s wide area from the pseudo-range correction value positioning error Enhance system information broadcast positioning error; The third calculation module, connected to the second calculation module, is used to convert the pseudo-range domain to the positioning domain according to the receiver information of the pseudo-airborne user and the integrity risk value preset by the system matrix calculation to obtain the monitoring system positioning error of the pseudo-airborne user, and calculate the ideal envelope value of the sum of the monitoring system positioning error and the wide-area augmentation system information broadcast positioning error to obtain the pseudo-airborne The ground monitoring protection level of the user, the positioning error of the monitoring system includes the positioning error caused by the thermal noise of the airborne user and the multipath of the fuselage, the positioning error caused by the ionosphere above the monitoring center and the troposphere above the monitoring center positioning error; The judgment module is connected with the third calculation module, and is used to compare the ground monitoring protection level of all visible satellites of the false airborne user with the alarm limit preset by the airborne user in turn, if the visible satellite If the ground monitoring protection level of the combination is less than the alarm limit, the visible satellite combination containing the largest number of satellites and the pseudorange correction value of each visible satellite in the visible satellite combination are sent to the airborne user. 9. A local area airport monitoring system, characterized in that it comprises: A plurality of receivers are used to receive satellite data sent by navigation satellites, perform analog-to-digital conversion on the satellite data, and send the satellite data after analog-to-digital conversion and its own receiver information to the monitoring center. The machine information includes the satellite elevation value of the visible satellite corresponding to the receiver, the real distance between the receiver and the visible satellite, and the number of visible satellites of each receiver; A monitoring center, connected with the receiver, is used to calculate the pseudo-range correction value of each satellite corresponding to the receiver according to the received satellite data, and calculate the pseudo-range correction value of the airborne user according to the receiver information. The error caused by the distance correction value and the error caused by the monitoring system are detected, and the ground monitoring protection level of the monitoring center is calculated, and by comparing the ground monitoring protection level with the user's preset alarm limit, the The best visible satellite combination, sending the best visible satellite combination and the pseudorange correction value of each visible satellite in the satellite combination to the airborne user, The monitoring center includes: a first calculation module, which is used to obtain the receiver information of each receiver itself and the satellite data received by the receiver from the navigation satellite, and use the enhanced information broadcast by the wide area augmentation system, the carrier phase observation value and the tropospheric The error model corrects the pseudorange information in the satellite data to obtain the pseudorange correction value of each satellite corresponding to each receiver, and the receiver information includes the satellite elevation angle value of the visible satellite corresponding to the receiver, the receiver The true distance between its visible satellites and the number of visible satellites per receiver; The second calculation module is connected with the first calculation module, and is used to select a receiver as a pseudo-airborne user, according to the receiver information of the pseudo-airborne user and the preset continuity requirements of the airborne user value, using the transformation matrix from the pseudo-range domain to the positioning domain to calculate the pseudo-range correction value positioning error of the pseudo-airborne user, and extract the pseudo-airborne user’s wide area from the pseudo-range correction value positioning error Enhance system information broadcast positioning error; The third calculation module, connected to the second calculation module, is used to convert the pseudo-range domain to the positioning domain according to the receiver information of the pseudo-airborne user and the integrity risk value preset by the system matrix calculation to obtain the monitoring system positioning error of the pseudo-airborne user, and calculate the ideal envelope value of the sum of the monitoring system positioning error and the wide-area augmentation system information broadcast positioning error to obtain the pseudo-airborne The ground monitoring protection level of the user, the positioning error of the monitoring system includes the positioning error caused by the thermal noise of the airborne user and the multipath of the fuselage, the positioning error caused by the ionosphere above the monitoring center and the troposphere above the monitoring center positioning error; The judgment module is connected with the third calculation module, and is used to compare the ground monitoring protection level of all visible satellites of the false airborne user with the alarm limit preset by the airborne user in turn, if the visible satellite If the combined ground monitoring protection level is less than the alarm limit, the visible satellite combination containing the largest number of satellites and the pseudorange correction value of each visible satellite in the visible satellite combination are sent to the airborne user; An airborne user, connected to the monitoring center, is used to calculate the position of the airborne user according to the optimal visible satellite combination and the pseudorange correction value of the visible satellite combination sent by the monitoring center.

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