Aircraft positioning method and system based on localizer and distance measuring equipment during the approach phase

Abstract

The present invention discloses a positioning method and system for an aircraft based on a localizer and a distance measuring equipment (DME) during the approach phase. The method includes: acquiring airborne navigation information and navigation measurement data output by airborne navigation equipment; determining whether the navigation measurement data meets a preset condition, and if so, proceeding to the next step; calculating the deviation angle of the aircraft from the localizer course; calculating the azimuth angle of the aircraft relative to the ground LOC station; calculating the horizontal distance between the aircraft and the ground DME station; calculating the horizontal distance between the aircraft and the ground LOC station; calculating the relative position of the aircraft and the ground LOC station in the horizontal plane; and calculating the longitude and latitude of the aircraft. The present invention is based on navigation infrastructure dedicated to civil aviation navigation, and the availability and integrity of its navigation signal sources are better guaranteed, thereby improving the accuracy and reliability of obtaining position information.

Description

Technical Field

[0001] The present invention belongs to the technical field of airliner positioning, and particularly relates to a positioning method and system for an aircraft based on a localizer and a distance measuring equipment during the approach phase. Background Art

[0002] The longitude and latitude position information required during the aircraft approach is currently mainly provided by navigation modes such as an inertial reference system / global positioning system (IRS / GPS) integrated navigation, a very high frequency omnidirectional range / distance measuring equipment (VOR / DME) navigation, and a DME / DME navigation. However, during the aircraft approach phase, the GPS signal is vulnerable to interference in the near-earth area, the VOR signal has poor availability at low altitudes, and it may be difficult to find two DME navigation stations with a suitable geometric configuration for DME / DME positioning, thus resulting in the inavailability of the above navigation methods during the aircraft approach phase. At this time, the localizer (LOC) and distance measuring equipment (DME) navigation signal sources provided by the instrument landing system (ILS) of the airport runway can be used for LOC / DME navigation positioning to provide an effective navigation and positioning means for the aircraft approach phase. Although some advanced transport aircraft abroad provide the LOC / DME navigation mode, its principle mechanism has not been made public. Summary of the Invention

[0003] The present invention provides a positioning method and system for an aircraft based on a localizer and a distance measuring equipment during the approach phase, which can be used as a supplement and backup for the navigation and positioning mode during the approach phase. By utilizing the advantages of good availability and integrity of the navigation signal sources of the LOC / DME navigation mode, the present invention can obtain relatively accurate position information, thereby improving the accuracy and reliability of navigation and positioning.

[0004] The present invention is achieved by the following technical solutions:

[0005] A positioning method for an aircraft based on a localizer and a distance measuring equipment during the approach phase includes:

[0006] Obtaining airborne navigation information and navigation measurement data output by airborne navigation equipment;

[0007] Judging whether the navigation measurement data meets a preset condition, and if so, proceeding to the next step;

[0008] Calculating the deviation angle of the aircraft from the localizer course according to the airborne navigation information and the navigation measurement data;

[0009] Calculating the azimuth angle of the aircraft relative to the ground LOC station according to the deviation angle;

[0010] Calculating the horizontal distance between the aircraft and the ground DME station;

[0011] Calculate the horizontal distance between the aircraft and the ground LOC station based on the horizontal distance between the aircraft and the ground DME station;

[0012] Calculate the relative position of the aircraft and the ground LOC station in the horizontal plane based on the horizontal distance between the aircraft and the ground LOC station and the azimuth angle;

[0013] Calculate the longitude and latitude of the aircraft based on the longitude and latitude of the ground LOC station and the relative position of the aircraft and the ground LOC station;

[0014] As a preferred embodiment, the acquisition of the airborne navigation information and the navigation measurement data output by the airborne navigation equipment of the present invention specifically includes:

[0015] Read the airport, runway and navigation station information from the airborne navigation database;

[0016] Obtain navigation measurement data from multiple airborne navigation equipment, including the modulation depth difference measured by the LOC of the airborne ILS equipment, the slant range measured by the airborne DME transponder, and the aircraft altitude measured by the airborne radio altimeter.

[0017] As a preferred embodiment, the judgment of whether the navigation measurement data meets the preset conditions in the present invention is specifically:

[0018] Judge whether the modulation depth difference measured by the LOC of the airborne ILS equipment meets DDM≤0.155;

[0019] Where DDM is the modulation depth difference.

[0020] As a preferred embodiment, the deviation angle of the aircraft from the localizer in the present invention is specifically: the angular deviation of the line connecting the aircraft and the ground LOC station relative to the center line of the localizer in the horizontal direction, and its calculation formula is:

[0021]

[0022] In the formula, θ DDM is the deviation angle of the aircraft from the localizer, DDM is the modulation depth difference, θ Width is the localizer width.

[0023] As a preferred embodiment, the calculation formula for the azimuth angle of the aircraft relative to the ground LOC station in the present invention is:

[0024] θ = θ LOC + θ Mag - θ DDM + 180°

[0025] In the formula, θ is the azimuth angle of the aircraft relative to the ground LOC station, θ LOC is the localizer course, θ Mag is the magnetic declination, θDDM is the deviation angle between the aircraft and the localizer course.

[0026] As a preferred embodiment, the formula for calculating the horizontal distance between the aircraft of the present invention and the DME station is:

[0027]

[0028] In the formula, r is the measured slant range output by the airborne DME transponder, and h is the aircraft altitude output by the airborne radio altimeter.

[0029] As a preferred embodiment, the formula for calculating the horizontal distance between the aircraft of the present invention and the ground LOC station is:

[0030]

[0031] In the formula, ρ is the horizontal distance between the aircraft and the ground LOC station, L RWY is the runway length, θ DDM is the deviation angle between the aircraft and the localizer course, d DME is the horizontal distance between the aircraft and the ground DME station.

[0032] As a preferred embodiment, calculating the relative position of the aircraft and the ground LOC station in the horizontal plane specifically includes:

[0033] In the horizontal plane, a rectangular coordinate system is established with the ground LOC station as the origin and the due east and due north directions as the positive directions of the X-axis and Y-axis respectively;

[0034] Calculate the coordinate position of the aircraft's projection in the horizontal plane, that is, the relative position of the aircraft and the ground LOC station in the horizontal plane. The calculation formula is:

[0035] X = ρ × sin(θ), Y = ρ × cos(θ)

[0036] In the formula, ρ is the horizontal distance between the aircraft and the ground LOC station, and θ is the azimuth angle of the aircraft relative to the ground LOC station.

[0037] As a preferred embodiment, the formula for calculating the longitude and latitude of the aircraft of the present invention is:

[0038]

[0039] In the formula,, X and Y are the relative position coordinates of the aircraft and the LOC station in the horizontal plane, λ LOC is the longitude of the LOC station, φ LOC is the latitude of the LOC station, R M and R N are respectively the curvature radii of the meridian and prime vertical circles of the WGS-84 geodetic reference ellipsoid at the location of the LOC station.

[0040] In a second aspect, the present invention provides a positioning system for an aircraft based on a localizer and a distance measuring equipment (DME) during the approach phase, which includes a data input module, a data processing module, and a data output module;

[0041] Among them, the data input module is used to obtain the on-board navigation information and the navigation measurement data output by the on-board navigation equipment;

[0042] The data processing module calculates the deviation angle of the aircraft from the localizer course, calculates the azimuth angle of the aircraft relative to the ground LOC station, calculates the horizontal distance between the aircraft and the ground DME station, calculates the horizontal distance between the aircraft and the ground LOC station, calculates the relative position of the aircraft and the ground LOC station in the horizontal plane, and calculates the longitude and latitude of the aircraft based on the longitude and latitude of the ground LOC station and the relative position of the aircraft and the ground LOC station;

[0043] The data output module is used to output the longitude and latitude of the aircraft calculated by the data processing module.

[0044] In a third aspect, the present invention provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the method of the present invention are implemented.

[0045] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method of the present invention are implemented.

[0046] The present invention has the following advantages and beneficial effects:

[0047] 1. The LOC / DME-based navigation and positioning method proposed by the present invention is based on the navigation infrastructure dedicated to civil aviation navigation, and the availability and integrity of its navigation signal source are well guaranteed, thereby improving the accuracy and reliability of obtaining position information.

[0048] 2. The LOC / DME-based navigation and positioning method proposed by the present invention is based on the accurately measured and compiled navigation database and the LOC signal with significantly improved direction-finding accuracy. Coupled with the small lateral error brought by the relatively close action range of the LOC signal, more accurate azimuth information can be measured, and then a more accurate position can be calculated, improving the positioning accuracy and reliability of the aircraft during the approach phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0050] Figure 1 Schematic diagram of the LOC / DME positioning principle according to an embodiment of the present invention.

[0051] Figure 2 Schematic diagram of the flow of the positioning method based on LOC / DME according to an embodiment of the present invention.

[0052] Figure 3 Block diagram of the principle of the electronic device according to an embodiment of the present invention.

[0053] Figure 4 Block diagram of the principle of the positioning system based on LOC / DME according to an embodiment of the present invention. Detailed implementation manners

[0054] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments and drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0055] Example 1

[0056] Currently, the latitude and longitude position information required by civil airliners during the approach process is mainly provided by IRS / GPS navigation or VOR / DME navigation methods. However, GPS signals are easily interfered with in the near area, and VOR signals have poor availability at low altitudes, resulting in the inability to accurately and reliably obtain latitude and longitude position information, and thus the accuracy and reliability of navigation positioning are relatively poor. Based on this, this embodiment proposes a positioning method for an aircraft based on a localizer and a distance measuring equipment during the approach phase. This embodiment uses the localizer (LOC) and distance measuring equipment (DME) navigation signal sources provided by the instrument landing system (ILS) of the airport runway for LOC / DME navigation positioning.

[0057] The LOC / DME method has the following advantages: 1) Based on the navigation infrastructure dedicated to civil aviation navigation, the availability and integrity of its navigation signal sources are better guaranteed; 2) Although the positioning principle is similar to the VOR / DME method, due to the precise measurement and compiled navigation database, as well as the LOC signal with significantly improved direction finding accuracy, and the smaller lateral error brought by the relatively close range of the LOC signal, the LOC / DME method can measure more accurate azimuth information and thus calculate a more accurate position.

[0058] ILS ground systems usually arrange the Distance Measuring Equipment (DME) transceiver antenna and the Glide Slope (GS) transmitting antenna together at the runway entrance, and arrange the Localizer (LOC) at the runway end. According to the ILS / DME approach procedure specified by the current Instrument Flight Rules (IFR), the ranging information of the airborne DME transponder is usually used to combine with the aircraft altitude information measured by the Radio Altimeter (LRA) to determine the deviation of the aircraft from the centerline of the localizer in the vertical section. It can be seen that the current application method only uses the DME ranging information as a substitute for the Marker Beacon (MB) signal, without deeply exploring its potential in radio positioning applications.

[0059] As Figure 1 shown, the Depth of Modulation Difference (DDM) output by the Localizer (LOC) receiving channel of the airborne ILS equipment can be relatively accurately converted into the angular deviation θ of the line connecting the aircraft and the localizer with respect to the centerline of the localizer in the horizontal direction. DDM , the longitude and latitude of the localizer, the altitude h of the DME antenna DME , the magnetic course angle θ of the localizer LOC , the magnetic declination θ Mag and the runway length L RWY can be obtained from the airborne navigation database. Therefore, in this embodiment, the azimuth angle of the aircraft relative to the localizer can be calculated based on θ DDM , θ LOC和 θ Mag , and the horizontal distance of the aircraft relative to the localizer can be calculated based on the measured distance of the airborne DME transponder, the aircraft altitude, h DME and L RWY . Using the above information, the longitude and latitude of the aircraft can be calculated.

[0060] As Figure 2 shown, the positioning method of this embodiment includes the following steps:

[0061] 1. Obtain the airborne navigation information and the navigation measurement data output by the airborne navigation equipment.

[0062] The input information required by the positioning method of this embodiment includes: 1) the airport, runway and navigation station information read from the airborne navigation database, and 2) the navigation measurement data output by multiple airborne navigation equipment, including the LOC measurement DDM output by the airborne ILS equipment (i.e., the Depth of Modulation Difference DDM output by the Localizer LOC receiving channel of the airborne ILS equipment. When the aircraft is flying towards the LOC station and is deflected to the right relative to the centerline of the localizer, the DDM is positive, and vice versa), the measured slant range r output by the airborne DME transponder, and the aircraft altitude h output by the airborne radio altimeter.

[0063] Modern civil airliners usually adopt a navigation database that complies with ARINC 424 standard, and the information shown in Table 1 can be read from it using the entry type and byte position as indexes. Among them, the magnetic declination is positive when it deviates eastward from the true north.

[0064] Table 1 Data required for the LOC / DME positioning method to be read from the ARINC 424 airborne navigation database

[0065]

[0066] Second, determine whether the modulation depth difference (DDM) output by the localizer (LOC) receiving channel of the airborne ILS device meets the preset conditions. If so, proceed to the next step.

[0067] In this embodiment, the preset condition is that the aircraft is located within the localizer sector of the instrument landing system. According to the existing industry standards, the edge of the sector is at the position where DDM = 0.155. Therefore, the preset condition in this embodiment is DDM ≤ 0.155.

[0068] Third, calculate the deviation angle of the aircraft from the localizer.

[0069] In this embodiment, the deviation angle of the aircraft from the localizer is the angular deviation of the line connecting the aircraft and the ground LOC station relative to the localizer center line in the horizontal direction.

[0070] In this embodiment, the deviation angle of the aircraft from the localizer is calculated using Equation (1):

[0071]

[0072] Fourth, calculate the azimuth angle of the aircraft relative to the ground LOC station.

[0073] In this embodiment, the azimuth angle of the aircraft relative to the ground LOC station is calculated using Equation (2):

[0074] θ = θ LOC + θ Mag - θ DDM + 180° (2)

[0075] Fifth, calculate the horizontal distance between the aircraft and the ground DME station.

[0076] In this embodiment, the horizontal distance between the aircraft and the ground DME station is calculated using Equation (3):

[0077]

[0078] Sixth, calculate the horizontal distance between the aircraft and the ground LOC station.

[0079] In this embodiment, the horizontal distance between the aircraft and the ground DME station is converted into the horizontal distance between the aircraft and the ground LOC station. Since the distance between the ground DME station and the runway centerline can be ignored relative to the runway length, the cosine theorem can be used to approximately calculate the horizontal distance between the aircraft and the ground LOC station, and the calculation formula is as shown in Equation (4):

[0080]

[0081] VII. Calculate the relative position of the aircraft and the ground LOC station in the horizontal plane.

[0082] In the horizontal plane, a rectangular coordinate system is established with the ground LOC station as the origin, and the due east and due north directions as the X-axis and Y-axis respectively. The coordinate position of the aircraft's projection in the horizontal plane is calculated, and the calculation formula is as shown in Equation (5):

[0083] X = ρ × sin(θ), Y = ρ × cos(θ) (5)

[0084] VIII. Based on the longitude and latitude of the ground LOC station and the relative position of the aircraft and the ground LOC station, calculate the longitude and latitude of the aircraft.

[0085] In this embodiment, based on the longitude and latitude of the ground LOC station, the relative position coordinates of the aircraft and the ground LOC station are converted into longitude and latitude, and the conversion formula is as shown in Equation (6):

[0086]

[0087] Wherein, and are the radii of curvature of the meridian and prime vertical of the WGS-84 geodetic reference ellipsoid at the location of the localizer respectively, and:

[0088] 1) R e = 6378137 (m) is the semi-major axis length of the WGS-84 geodetic reference ellipsoid;

[0089] 2) e = 0.08181919084265 is the eccentricity of the WGS-84 geodetic reference ellipsoid.

[0090] This embodiment also proposes an electronic device for executing the above method of this embodiment.

[0091] Specifically, as Figure 3As shown, the electronic device includes a processor, an internal memory, and a system bus; various device components including the internal memory and the processor are connected to the system bus. The processor is a hardware component used to execute computer program instructions through basic arithmetic and logical operations in a computer system. The internal memory is a physical device for temporarily or permanently storing computing programs or data (e.g., program status information). The system bus can be any one of several types of bus structures, including a memory bus or memory controller, a peripheral bus, and a local bus. The processor and the internal memory can communicate data through the system bus. The internal memory includes a read-only memory (ROM) or flash memory (not shown in the figure), and a random access memory (RAM), and the RAM is usually the main memory that loads the operating system and computer programs.

[0092] Generally, the electronic device may also include an external storage device. The external storage device can be selected from a variety of computer-readable media, which refers to any available media that can be accessed by a computer device, including both removable and fixed media. For example, computer-readable media includes, but is not limited to, flash memory (micro SD card), CD-ROM, digital versatile disc (DVD), or other optical disc storage, magnetic tape cartridges, tapes, magnetic disk storage, or other magnetic storage devices, or any other media that can be used to store the required information and can be accessed by a computer device.

[0093] The electronic device can be logically connected to one or more network terminals in a network environment. It should be noted that other computer systems including more or fewer subsystems than the electronic device can also be applicable to the invention.

[0094] As described in detail above, the electronic device applicable to this embodiment can perform specified operations of the positioning method based on a localizer and a distance measuring equipment. The electronic device executes these operations in the form of software instructions running on the processor in a computer-readable medium. These software instructions can be read into the memory from a storage device or from another device through a local area network interface. The software instructions stored in the memory enable the processor to execute the above-mentioned processing method of group member information. In addition, the present invention can also be implemented by a hardware circuit or a combination of a hardware circuit and software instructions. Therefore, implementing this embodiment is not limited to any specific combination of hardware circuit and software.

[0095] Embodiment 2

[0096] This embodiment proposes a positioning system for an aircraft based on a localizer and a distance measuring equipment during the approach phase, as Figure 4 shown, including a data input module 10, a data processing module 20, and a data output module 30.

[0097] Among them, the data input module 10 is used to obtain the navigation information recorded and the navigation measurement data output by multiple on-board navigation devices; specifically, the data input module 10 of this embodiment reads the airport, runway, and navigation station information from the on-board navigation database, and obtains the navigation measurement data from multiple on-board navigation devices, including the LOC measurement DDM output by the on-board ILS device (i.e., the modulation depth difference DDM output by the course beacon LOC receiving channel of the on-board ILS device), the measured slant range r output by the on-board DME transponder, and the aircraft altitude h output by the on-board radio altimeter.

[0098] The data processing module 20 includes a monitoring unit, a deviation angle calculation unit, a bearing angle calculation unit, a first horizontal distance calculation unit, a second horizontal distance calculation unit, a relative position coordinate acquisition unit, and an aircraft longitude and latitude calculation unit.

[0099] The monitoring unit of this embodiment is used to determine whether the modulation depth difference (DDM) output by the course beacon (LOC) receiving channel of the on-board ILS device meets the preset conditions; the determination method is the same as that in the above-mentioned Embodiment 1, and will not be elaborated here.

[0100] The deviation angle calculation unit of this embodiment is used to calculate the deviation angle between the aircraft and the course.

[0101] The bearing angle calculation unit of this embodiment is used to calculate the bearing angle of the aircraft relative to the ground LOC station.

[0102] The first horizontal distance calculation unit of this embodiment is used to calculate the horizontal distance between the aircraft and the ground DME station.

[0103] The second horizontal distance calculation unit of this embodiment is used to calculate the horizontal distance between the aircraft and the ground LOC station.

[0104] The relative position coordinate acquisition unit of this embodiment is used to calculate the relative position of the aircraft and the ground LOC station in the horizontal plane.

[0105] The aircraft longitude and latitude calculation unit of this embodiment calculates the longitude and latitude of the aircraft based on the longitude and latitude of the ground LOC station and the relative position of the aircraft and the ground LOC station.

[0106] The specific calculation processes of the above calculation units in this embodiment are the same as those in the above-mentioned Embodiment 1, and will not be elaborated here.

[0107] The data output module 30 of this embodiment outputs the longitude and latitude information of the aircraft obtained by the data processing module.

[0108] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Aircraft positioning method based on localizer and distance measuring equipment in the approach phase, Characterized in that, Comprising: Obtain onboard navigation information and navigation measurement data output by onboard navigation equipment; Judge whether the navigation measurement data meets the preset conditions, if so, proceed to the next step; Calculate the deviation angle of the aircraft from the localizer course according to the onboard navigation information and the navigation measurement data; Calculate the azimuth angle of the aircraft relative to the ground LOC station according to the deviation angle; Calculate the horizontal distance between the aircraft and the ground DME station; Calculate the horizontal distance between the aircraft and the ground LOC station according to the horizontal distance between the aircraft and the ground DME station; Calculate the relative position of the aircraft and the ground LOC station in the horizontal plane according to the horizontal distance between the aircraft and the ground LOC station and the azimuth angle; Calculate the longitude and latitude of the aircraft according to the longitude and latitude of the ground LOC station and the relative position of the aircraft and the ground LOC station; Obtain onboard navigation information and navigation measurement data output by onboard navigation equipment, specifically including: Read airport, runway and navigation station information from the onboard navigation database; Obtain navigation measurement data from multiple onboard navigation equipment, including the modulation depth difference measured by the LOC of the onboard ILS equipment, the slant range measured by the onboard DME transponder and the aircraft height measured by the onboard radio altimeter; Judge whether the navigation measurement data meets the preset conditions, specifically: Judge whether the modulation depth difference measured by the LOC of the onboard ILS equipment satisfies DDM≤0.155; Wherein, DDM is the modulation depth difference.

2. The aircraft positioning method based on localizer and distance measuring equipment in the approach phase according to claim 1, Characterized in that, The deviation angle of the aircraft from the localizer course is specifically: the angular deviation of the line connecting the aircraft and the ground LOC station relative to the center line of the localizer course in the horizontal direction, and its calculation formula is: where θ DDM is the deviation angle between the aircraft and the localizer, DDM is the modulation depth difference, and θ Width is the localizer width.

3. The aircraft positioning method based on localizer and distance measuring equipment in the approach phase according to claim 1, Characterized in that, The calculation formula for the azimuth angle of the aircraft relative to the ground LOC station is: θ = θ LOC + θ Mag - θ DDM + 180° Wherein, θ is the azimuth angle of the aircraft relative to the ground LOC station, θ LOC is the course of the localizer, θ Mag is the magnetic declination, θ DDM is the deviation angle of the aircraft from the localizer.

4. The aircraft positioning method based on localizer and distance measuring equipment in the approach phase according to claim 1, Characterized in that, The calculation formula for the horizontal distance between the aircraft and the DME station is: In the formula, r is the measured slant range output by the onboard DME transponder, and h is the aircraft height output by the onboard radio altimeter.

5. The aircraft positioning method based on localizer and distance measuring equipment in the approach phase according to claim 1, Characterized in that, The calculation formula for the horizontal distance between the aircraft and the ground LOC station is: where ρ is the horizontal distance between the aircraft and the ground LOC station, L RWY is the runway length, θ DDM is the deviation angle of the aircraft from the localizer, d DME is the horizontal distance between the aircraft and the ground DME station.

6. The aircraft positioning method based on localizer and distance measuring equipment in the approach phase according to claim 1, Characterized in that, Calculating the relative position of the aircraft and the ground LOC station in the horizontal plane specifically is: In the horizontal plane, establish a rectangular coordinate system with the ground LOC station as the origin and the due east and due north directions as the positive directions of the X-axis and Y-axis respectively; Calculate the coordinate position of the aircraft's projection in the horizontal plane, that is, the relative position of the aircraft and the ground LOC station in the horizontal plane, and the calculation formula is: X = ρ×sin(θ), Y = ρ×cos(θ) Where ρ is the horizontal distance between the aircraft and the ground LOC station, and θ is the azimuth angle of the aircraft relative to the ground LOC station.

7. The positioning method of an aircraft in the approach phase based on the localizer and the distance measuring equipment according to claim 1, characterized in that, the calculation formula for the longitude and latitude of the aircraft is: wherein, X and Y are the relative position coordinates of the aircraft and the LOC station in the horizontal plane, λ LOC is the longitude of the LOC station, φ LOC is the latitude of the LOC station, R M and R N are respectively the curvature radii of the meridian and the prime vertical of the WGS-84 geodetic reference ellipsoid at the location of the LOC station.

8. The positioning system of an aircraft in the approach phase based on the localizer and the distance measuring equipment, characterized in that, it includes a data input module, a data processing module and a data output module; wherein, the data input module is used to obtain the airborne navigation information and the navigation measurement data output by the airborne navigation equipment; the data processing module calculates the deviation angle between the aircraft and the localizer course, calculates the azimuth angle of the aircraft relative to the ground LOC station, calculates the horizontal distance between the aircraft and the ground DME station, calculates the horizontal distance between the aircraft and the ground LOC station, calculates the relative position of the aircraft and the ground LOC station in the horizontal plane, and calculates the longitude and latitude of the aircraft according to the longitude and latitude of the ground LOC station and the relative position of the aircraft and the ground LOC station; the data output module is used to output the longitude and latitude of the aircraft calculated by the data processing module; the obtaining of the airborne navigation information and the navigation measurement data output by the airborne navigation equipment specifically includes: reading airport, runway and navigation station information from the airborne navigation database; obtaining navigation measurement data from multiple airborne navigation equipment, including the modulation depth difference measured by the LOC of the airborne ILS equipment, the slant range measured by the airborne DME transponder and the aircraft altitude measured by the airborne radio altimeter; the data processing module includes a monitoring unit, and the monitoring unit is used to judge whether the modulation depth difference meets the preset condition, and only if it is, the calculation of the deviation angle is carried out; wherein, judging whether the modulation depth difference meets the preset condition specifically is: judging whether the modulation depth difference meets DDM≤0.155; where DDM is the modulation depth difference.

9. An electronic device, including a memory and a processor, and the memory stores a computer program, characterized in that, when the processor executes the computer program, it implements the steps of the method according to any one of claims 1-7.

10. A computer-readable storage medium, on which a computer program is stored, characterized in that, when the computer program is executed by the processor, it implements the steps of the method according to any one of claims 1-7.

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