Interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analysis of satellite service data

Abstract

The invention provides an interference SAR satellite sub-satellite point trajectory drift monitoring method based on analysis of satellite service data, and the method comprises the steps: carrying out the partitioning of a to-be-analyzed GNSS original observation data package, reading data blocks one by one, and extracting the space coordinates of a satellite and the corresponding time; extracting satellite space coordinates of any satellite orbit in any regression period before and after Z = zero in a WGS84 coordinate system, converting the satellite space coordinates into latitude and longitude of a sub-satellite point, and interpolating to obtain the longitude of the sub-satellite point at the equator; taking a satellite regression cycle as a time interval, repeatedly obtaining sub-satellite point longitudes of corresponding satellite orbits at the equator in a plurality of regression cycles, and after equalization processing, determining a reference sub-satellite point of a single satellite orbit at the equator in the satellite regression cycle; according to orbit distribution in a satellite regression period, the longitude of a reference sub-satellite point of a single satellite orbit in the satellite regression period at the equator is utilized to determine the sub-satellite point longitude of all regression orbits in the satellite regression period at the equator, and based on the longitude, the drift distance of the sub-satellite point trajectory of the satellite in each date is determined.

Description

Technical Field

[0001] The invention belongs to the field of earth satellite observation, and in particular relates to a method for monitoring sub-satellite point trajectory drift of an interferometric SAR satellite based on analyzing satellite service data. Background Art

[0002] Spaceborne re-orbit interferometry SAR is a further application based on spaceborne SAR imaging technology. It currently plays a key role in global elevation mapping and deformation measurement. Re-orbit interferometry requires the satellite to conduct at least two repeated observations of the same imaging area, and has strict requirements on the observation angle and baseline length. However, during the operation of the satellite, the satellite is affected by perturbations such as atmospheric drag, the non-spherical gravity of the earth, and the gravity of the sun and the moon. The flight orbit will deviate from the predetermined orbit, causing the sub-satellite point trajectory to drift, resulting in a larger interference baseline within a revisit cycle and greater decoherence. In order to achieve the accuracy required by SAR interferometry, the satellite's flight trajectory must be kept within half the critical baseline of the predetermined orbit. How to calculate and monitor the drift of the satellite orbit is particularly important for the subsequent SAR payload observation data business applications. Summary of the invention

[0003] In order to overcome the deficiencies in the prior art, the inventors have conducted intensive research and provided a method for monitoring the sub-satellite point trajectory drift of an interferometric SAR satellite based on the analysis of satellite service data, in order to use the analyzed satellite service data to accurately calculate the satellite sub-satellite point trajectory drift and implement high-precision orbit drift monitoring of interferometric SAR satellites.

[0004] The technical solution provided by the present invention is as follows:

[0005] In a first aspect, a method for monitoring sub-satellite point trajectory drift of an interferometric SAR satellite based on parsing satellite service data comprises:

[0006] The GNSS original observation data packet to be parsed is processed in blocks, and the data blocks are read one by one to extract the satellite spatial coordinates and corresponding time;

[0007] According to the acquired satellite space coordinates and corresponding time, the satellite space coordinates of any satellite orbit in any regression period before and after the Z-axis coordinate value of the WGS84 coordinate system is zero are extracted; each satellite space coordinate is converted into the longitude and latitude of the sub-satellite point, and the longitude of the sub-satellite point at the equator is obtained by interpolation;

[0008] Using the satellite regression period as the time interval, repeatedly obtain the longitude of the sub-satellite point at the equator of the corresponding satellite orbit in multiple regression periods, and determine the reference sub-satellite point at the equator of a single satellite orbit in the satellite regression period by averaging the longitude of the sub-satellite point;

[0009] According to the orbital distribution within the satellite regression period, the longitude of the reference sub-satellite point at the equator of a single satellite orbit within the satellite regression period is used to determine the sub-satellite point longitude at the equator of all regression orbits within the satellite regression period. Combined with the sub-satellite point longitude of the satellite orbit at the equator on each date, the satellite orbit drift on each date is determined.

[0010] In a second aspect, an interferometric SAR satellite sub-satellite point trajectory drift monitoring device based on analyzing satellite service data comprises:

[0011] Memory, used to store computer programs;

[0012] The processor is used to implement the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data described in the first aspect when executing the program stored in the memory.

[0013] In a third aspect, a computer-readable storage medium is provided, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data as described in the first aspect is implemented.

[0014] In a fourth aspect, a computer program product is provided, comprising: a computer program code, wherein the computer program code is loaded and executed by a computer so as to enable the computer to implement the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data as described in the first aspect.

[0015] The interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data provided by the present invention has the following beneficial effects:

[0016] The invention provides an interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data. The method comprises the following steps: processing a GNSS original observation data packet to be analyzed in blocks, reading the data blocks one by one and extracting satellite space coordinates and corresponding time; extracting satellite space coordinates of any satellite orbit in any regression period before and after the Z-axis coordinate value of the WGS84 coordinate system is zero according to the obtained satellite space coordinates and corresponding time; converting each satellite space coordinate into sub-satellite point longitude and latitude, and interpolating to obtain the sub-satellite point longitude at the equator; taking the satellite regression period as a time interval, repeatedly obtaining the sub-satellite point longitudes of the corresponding satellite orbits at the equator in multiple regression periods, and determining the reference sub-satellite point of a single satellite orbit at the equator in the satellite regression period by averaging the sub-satellite point longitudes; determining the sub-satellite point longitudes of all regression orbits at the equator in the satellite regression period according to the orbit distribution in the satellite regression period, and determining the satellite orbit drift amount at each date in combination with the sub-satellite point longitudes of the satellite orbits at the equator on each date. The sub-satellite point trajectory drift monitoring method of the present invention determines the sub-satellite point longitude of all regression orbits at the equator within the regression period and uses it as the sub-satellite point longitude of the reference orbit to calculate the subsequent satellite orbit drift. The method is reasonable and the data reliability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the flow chart of GNSS raw observation data segmentation processing;

[0018] Figure 2 A schematic diagram of the satellite's trajectory during a certain period of time and its spatial position above the equator;

[0019] Figure 3 Schematic diagram of the periodic spatial position distribution of satellites at Z = 0 in the WGS-84 coordinate system;

[0020] Figure 4 This is a schematic diagram of the corresponding relationship between the satellite's spatial position and the longitude and latitude of the sub-satellite point;

[0021] Figure 5 This is a schematic diagram of the relationship between geodetic coordinates and longitude and latitude;

[0022] Figure 6 It is a line graph of the satellite sub-satellite point trajectory drift. DETAILED DESCRIPTION

[0023] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0024] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0025] The present invention provides a method for monitoring the sub-satellite point trajectory drift of an interferometric SAR satellite based on analyzing satellite service data. Figure 1 As shown, the following steps are included:

[0026] S1: Analysis of GNSS (Global Navigation Satellite System) raw observation data.

[0027] Get the GNSS original observation data packet to be parsed, divide the data packet into blocks according to the set size, read the data blocks one by one and extract the satellite spatial coordinates and corresponding time.

[0028] S1.1: GNSS raw observation data segmentation processing

[0029] GNSS files have large data volumes. If you want to read the entire file into memory at once, you need to ensure that the computer has enough available memory to store the entire file. To avoid insufficient memory during the parsing process, the GNSS file to be parsed is cut into blocks, and then data is extracted from the cut files separately.

[0030] The GNSS raw observation data to be analyzed is cut into blocks. During the cutting process, the size of the block and the pointer offset of the starting position of each data block must be determined first (see Figure 2 ). The slice size can be determined according to the computer performance, and the pointer offset is generally the number of bytes of a complete frame of GNSS data. For example, in this embodiment, the slice size of the original satellite observation data (data format see Table 1) used is set to slice=3MB, and the pointer offset is the size of a complete data frame, that is, offset=2048byte.

[0031] Table 1 Examples of original satellite observation data

[0032]

[0033]

[0034] S1.2: Extraction and analysis of GNSS raw observation data

[0035] Extract and parse the observation data of the GNSS data block to obtain the satellite space coordinates and corresponding time.

[0036] S1.2.1, find the frame header byte of valid GNSS data. Read the GNSS data block in binary form, and find the valid GNSS data corresponding to a whole frame according to the frame header byte of the GNSS original observation data format in Table 1 and the byte length of a complete data frame.

[0037] S1.2.2. After reading the corresponding information, convert the bytes corresponding to the user space position into the spatial coordinates (X, Y, Z) in the WGS84 coordinate system, and convert the bytes related to the time information such as week, week seconds, decimal seconds, etc. according to the user space position, the position and length of the bytes related to the time information such as week, week seconds, decimal seconds, etc. into time.

[0038] In this embodiment, the user space position (X, Y, Z) is at the 6th-9th, 10th-13th, and 14th-17th bytes in a complete data frame, each occupying 32 bits. The GPS week and week seconds, GPS decimal seconds, and GPS cumulative clock difference seconds are at the 27th-30th, 31st-34th, and 35th-38th bytes of a complete data frame, each occupying 32 bits. The BD2 week and week seconds, BD2 decimal seconds, and BD2 cumulative clock difference seconds are at the 39th-42nd, 43rd-46th, and 47th-50th bytes of a complete data frame, each occupying 32 bits.

[0039] In this embodiment, the spatial position data is bit-operated using a signed bit data representation method, and the GPS or BD2 time information is bit-operated and converted into Coordinated Universal Time (UTC) or Beijing time.

[0040] The conversion of GPS or BD2 time system to UTC time system is as follows:

[0041] UTCtime=BeginTime+difFromBegin+TimeDelay Formula 1

[0042] difFromBegin=Week×604800+WIS+WINS×10 -9 Formula 2

[0043] Where, UTCtime is UTC time. BeginTime is the starting point of the navigation system time, which is defined as UTC0 on January 6, 1980 for the GPS navigation system and UTC0 on January 1, 2006 for the BD2 navigation system. difFromBegin is the time interval between the received time and the starting point, in seconds. TimeDelay is the leap second correction. Since GPS and BD2 time do not make corrections for whole seconds with UTC leap seconds, GPS time is 18 seconds ahead of UTC time, TimeDelay=18, and BD2 time lags UTC time by 4 seconds, TimeDelay=-4. This value will be corrected with UTC leap seconds. Week is GPS / BD2 week; WIS is GPS / BD2 week seconds; WINS is GPS / BD2 week fractional seconds.

[0044] S1.2.3, after moving the pointer backward by the byte length of one frame of GNSS data, execute S1.2.1 to S1.2.2 in a loop until the GNSS data block is read, and write the extracted satellite spatial coordinates and corresponding time into the dat file and save it.

[0045] S1.2.4, process all the cut GNSS data blocks according to S1.2.1 to S1.2.3 until all the GNSS data blocks are processed, and finally obtain the satellite spatial coordinate files corresponding to each time.

[0046] S2: Determination of satellite base sub-satellite point

[0047] Extract the spatial coordinate information and time information of satellites on different dates through the original GNSS observation data of different periods. Extract the spatial coordinates (X, Y, Z) of any satellite orbit before and after Z=0 in the WGS84 coordinate system within any regression period (see Figure 3 and Figure 4 ); remove gross errors (hereinafter referred to as "gross errors") of the satellite's spatial coordinates (X, Y, Z) before and after Z = 0; convert each spatial coordinate after the gross errors are removed into the longitude and latitude of the sub-satellite point, and interpolate to obtain the longitude of the sub-satellite point at the equator; use the satellite regression period as the time interval, repeatedly obtain the sub-satellite point longitude at the equator corresponding to the satellite orbit in multiple regression periods, and determine the reference sub-satellite point at the equator of a single satellite orbit in the satellite regression period by averaging the sub-satellite point longitude according to the periodic distribution of the satellite orbit.

[0048] S2.1: Valid data extraction

[0049] The coordinate origin of the WGS-84 coordinate system is the center of mass of the earth, the Z axis points to the direction of the earth's pole in the BIH1984.0 protocol, the X axis points to the intersection of the zero meridian plane of 1984.0 and the equator, and the Y axis is perpendicular to the X axis and the Z axis, forming a right-handed system. The satellite passes through the equator twice in one orbit around the earth. Before and after crossing the equator, the Z value has the opposite sign. The Z value changes from positive to negative when the satellite descends, and the Z value changes from negative to positive when the satellite ascends. Therefore, from the satellite spatial coordinate information and time information obtained from the original GNSS observation data, multiple spatial positions and time information of satellites before and after Z=0 when the satellite descends or ascends on any satellite orbit within any regression period are extracted.

[0050] S2.2: Gross Error Removal

[0051] During the flight of the satellite, the positioning signal may be lost. At this time, the satellite GNSS information is a filler value with no practical significance. If this value appears before or after Z=0 in the WGS84 coordinate system, it will affect the calculation of the satellite coordinates (X, Y) at Z=0. By fitting multiple sets of spatial coordinates (X, Y, Z) before and after Z=0 in the WGS84 coordinate system, the continuity of the X-axis and Y-axis data values ​​in the satellite spatial coordinates (X, Y, Z) before and after Z=0 is judged to determine whether the satellite has lost the positioning signal. If it is lost at a certain spatial coordinate, the abnormal value is removed and replaced with the fitted value.

[0052] Based on the continuity of the satellite orbit, this embodiment performs polynomial curve fitting based on the least squares method on multiple groups of spatial coordinates (X, Y, Z) before and after Z=0 of the WGS84 coordinate system, calculates the standard deviation using the coordinate value and the corresponding fitting value, determines the gross error threshold according to the principle of 3 times the standard deviation (3σ), finds the gross error and replaces it with the fitting value.

[0053] For the X coordinate value, considering it as a function of time t, there is a point set:

[0054] P={(t1,x1),(t2,x2),…(t M ,x M )} Formula 3

[0055] M is the number of spatial coordinate groups before and after Z = 0, where t i ∈R and x i ∈R relation satisfies the function:

[0056] f(t i )=x i ,i=1,2,...,M Formula 4

[0057] Fit the time t and the X-axis coordinate with an N-degree polynomial:

[0058]

[0059] Among them, ω j (j=0,1,2,…,N) are the coefficients of the polynomial. The square sum of the residuals ε is used to characterize the fitting effect:

[0060]

[0061] According to the least squares principle, we can solve ω on the right side of equation 6. j The partial derivative of is set to 0, and a set of fitting coefficients is solved to minimize ε, and the fitting polynomial is obtained.

[0062] The gross error threshold is set to 3 times the standard deviation. When the difference between the residual, that is, the X-coordinate value and its fitted value, is greater than the threshold, the X-coordinate value is used to replace the gross error coordinate value. The gross error threshold can be expressed by the following formula.

[0063]

[0064] In the formula is the average value of the actual X coordinate value.

[0065] Similarly, the Y coordinate values ​​and Z coordinate values ​​are subjected to gross error removal and fitted value replacement.

[0066] S2.3: Calculation of latitude and longitude of sub-satellite point

[0067] The sub-satellite point is defined as the intersection of the line connecting the satellite and the center of the earth on the surface of the WGS-84 earth ellipsoid. According to the multiple spatial coordinates of the satellites before and after Z=0 extracted in S2.1 and de-roughened in S2.2, the longitude and latitude (Lon, Lat) and elevation H information of the sub-satellite point corresponding to the multiple spatial coordinates are determined. The corresponding relationship between the geodetic coordinates and the longitude and latitude is shown in Figure 5 .

[0068]

[0069] Where a = 6378137.0 meters, which is the major semi-axis of the earth ellipsoid in the WGS-84 coordinate system, b = 6356752.3142 meters, which is the minor semi-axis of the earth ellipsoid, and e = 6378137.0 meters, which is the minor semi-axis of the earth ellipsoid in the WGS-84 coordinate system. 2 is the first eccentricity, e' 2 is the second eccentricity, and N is the radius of the eccentric circle.

[0070]

[0071]

[0072]

[0073]

[0074] Where B is the geodetic latitude.

[0075] S2.4: Interpolate the longitude and latitude of the sub-satellite point to obtain the longitude of the sub-satellite point at the equator

[0076] During the operation of the satellite, there is a linear relationship between the longitude and latitude of the sub-satellite point. The Lagrange interpolation method is used to interpolate the longitude information of the sub-satellite point before and after Z = 0 when the satellite is descending or ascending, and the longitude (Lon) of the satellite sub-satellite point at the equator (Lat = 0) is solved, as shown in the following formula 8:

[0077]

[0078] M is the number of spatial coordinate groups before and after Z=0.

[0079] In this embodiment, the longitude at the equator is obtained by interpolating five points before and after the equator, and Lat=0 is substituted into the above formula, and then:

[0080]

[0081] Taking the satellite regression period as the interval, the multiple spatial positions and time information of the satellites before and after Z=0 in the GNSS original observation data are repeatedly extracted, the gross errors are removed, the longitude and latitude of the sub-satellite point are converted, and the longitude and latitude of the sub-satellite point are interpolated to obtain the longitude of the sub-satellite point at the equator corresponding to the satellite orbit in multiple regression periods, thereby obtaining the periodic sub-satellite point distribution of satellites at the equator.

[0082] S2.5: Determination of reference sub-satellite point

[0083] According to the periodic sub-satellite point distribution of the satellite at the equator, the average longitude at the equator is used as the longitude of the reference sub-satellite point of a single satellite orbit at the equator during the satellite regression period to obtain the reference sub-satellite point at the equator; the subsequent satellite sub-satellite point trajectory drift is calculated based on the reference sub-satellite point. The longitude of the reference sub-satellite point at the equator is expressed as:

[0084]

[0085] In the formula, Lon i is the longitude value of the sub-satellite point at the equator on different return dates of a certain satellite orbit, and k is the total number of satellite orbits involved in the calculation.

[0086] S3: Sub-satellite point trajectory drift calculation

[0087] In the above step S2.5, the reference sub-satellite point of the satellite at the equator is the average longitude of the sub-satellite point on multiple return dates with the satellite return period as the interval. The reference sub-satellite point is only the reference sub-satellite point of a certain satellite orbit on a certain day in the return period; the calculation of the satellite daily trajectory drift needs to be based on the reference sub-satellite point, and the drift is calculated according to the return orbit distribution in the satellite return period.

[0088] S3.1: Longitude of all reference orbital sub-satellite points within the regression period

[0089] The longitude difference between regression orbits within a regression cycle is defined as the longitude difference of the sub-satellite points of adjacent satellite regression orbits at the equator within a regression cycle. The sub-satellite point longitudes of all regression orbits at the equator within a regression cycle are calculated based on the regression cycles and the reference sub-satellite point longitudes determined in step S2.5, and are used as the reference orbit sub-satellite point longitudes.

[0090] The difference in longitude between adjacent tropical orbits at the equator:

[0091] Lon interval =360 / n Formula 12

[0092] Then the longitude of the sub-satellite point of the reference orbit within a regression period can be expressed as:

[0093] Lon stand_pathi =Lon stand +i*Lon interval Formula 13

[0094] Where n is the total number of regression orbits in one regression cycle of the satellite, and i is the number of regression orbits between the regression orbit and the reference sub-satellite point determined in step S2.5. stand_pathi >180, then

[0095] Lon stand_pathi =Lon stand_pathi -360 Type 14

[0096] S3.2: Drift distance calculation

[0097] Read the satellite space coordinate files corresponding to the times calculated from the GNSS original observation data in step S1, repeat step S2, and obtain the longitude of the sub-satellite point at the equator of the satellite orbit on each date; compare and analyze the longitude of the sub-satellite point at the equator of each date with the longitude of the sub-satellite point of the corresponding reference orbit, and obtain the longitude difference of the sub-satellite point trajectory drift, and convert the longitude difference into the sub-satellite point trajectory drift distance at the equator.

[0098]

[0099] Where m is the number of satellite orbits involved in the calculation of satellite orbit ascending or descending in one day, and a is the major semi-axis of the Earth ellipsoid in the WGS-84 coordinate system.

[0100] Through the above steps, the satellite sub-satellite point trajectory drift within a period of time is calculated, such as Figure 6 shown.

[0101] The present invention also provides an interferometric SAR satellite sub-satellite point trajectory drift monitoring device based on analyzing satellite service data, comprising:

[0102] Memory, used to store computer programs;

[0103] The processor is used to implement the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data described in the first aspect when executing the program stored in the memory.

[0104] It should be understood that the processor may be a CPU, or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. It is worth noting that the processor may be a processor supporting the advanced reduced instruction set machine (ARM) architecture.

[0105] The above-mentioned memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. The memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0106] The memory may be a volatile memory or a nonvolatile memory, or may include both volatile and nonvolatile memory. Among them, the nonvolatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available. For example, static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM) and direct memory bus random access memory (DR RAM).

[0107] The present invention also provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data described in the first aspect is implemented.

[0108] The present invention also provides a computer program product, which includes: computer program code, which is loaded and executed by a computer to enable the computer to implement the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data as described in the first aspect.

[0109] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the process or function according to the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integration. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state drive (solid state disk)), etc.

[0110] Those of ordinary skill in the art will appreciate that, in conjunction with the various method steps described in the embodiments disclosed herein, they can be implemented in software, hardware, firmware, or any combination thereof. In order to clearly illustrate the interchangeability of hardware and software, the steps and components of each embodiment have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those of ordinary skill in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0111] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0112] When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer program instructions. As an example, the method of the embodiment of the present application can be described in the context of machine executable instructions, such as a program module executed in a device on a real or virtual processor of the target.

[0113] The computer program code for implementing the method of the embodiment of the present application can be written in one or more programming languages. These computer program codes can be provided to the processor of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the computer or other programmable data processing device, causes the specified function / operation to be implemented. The program code can be executed completely on a computer, partially on a computer, as an independent software package, partially on a computer and partially on a remote computer or completely on a remote computer or server.

[0114] In the context of the embodiments of the present application, computer program codes or related data may be carried by any appropriate carrier to enable a device, apparatus or processor to perform the various processes and operations described above. Examples of carriers include signals, computer readable media, and the like.

[0115] A machine-readable medium may be any tangible medium that contains or stores a program for or related to an instruction execution system, apparatus, or device. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More detailed examples of machine-readable storage media include an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0116] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0117] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0118] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for monitoring sub-satellite point trajectory drift of an interferometric SAR satellite based on analyzing satellite service data, characterized in that: include: The GNSS original observation data packet to be parsed is processed in blocks, and the data blocks are read one by one to extract the satellite spatial coordinates and corresponding time; According to the acquired satellite space coordinates and corresponding time, the satellite space coordinates of any satellite orbit in any regression period before and after the Z-axis coordinate value of the WGS84 coordinate system is zero are extracted; each satellite space coordinate is converted into the longitude and latitude of the sub-satellite point, and the longitude of the sub-satellite point at the equator is obtained by interpolation; Using the satellite regression period as the time interval, repeatedly obtain the longitude of the sub-satellite point at the equator of the corresponding satellite orbit in multiple regression periods, and determine the reference sub-satellite point at the equator of a single satellite orbit in the satellite regression period by averaging the longitude of the sub-satellite point; According to the orbital distribution within the satellite regression period, the longitude of the reference sub-satellite point at the equator of a single satellite orbit within the satellite regression period is used to determine the sub-satellite point longitude at the equator of all regression orbits within the satellite regression period. Combined with the sub-satellite point longitude of the satellite orbit at the equator on each date, the satellite orbit drift on each date is determined.

2. The interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data according to claim 1 is characterized in that: The step of reading data blocks one by one and extracting satellite space coordinates and corresponding time includes: Read the GNSS data block, and find out the valid GNSS data corresponding to a whole frame according to the frame header byte of the GNSS original observation data format and the byte length of the complete data frame; After reading the corresponding information of the whole frame of valid GNSS data found according to the set position and length of the relevant bytes of the user space position and time information, the bytes corresponding to the user space position are converted to the satellite space coordinates in the WGS84 coordinate system, and the relevant bytes of the time information are converted into time; The operation of searching for valid GNSS data of the whole frame, obtaining satellite spatial coordinates and corresponding time is repeated until the GNSS data block is read, and the extracted satellite spatial coordinates and corresponding time are written into a file and saved; All GNSS data blocks are processed according to the operation of searching for the entire frame of valid GNSS data, obtaining the satellite spatial coordinates and the corresponding time, until all GNSS data blocks are processed.

3. The interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data according to claim 1 is characterized in that: After extracting the space coordinates of the satellite of any satellite orbit in any regression period before and after the Z-axis coordinate value of the WGS84 coordinate system is zero, the method further includes: removing gross errors from the space coordinates of the satellite before and after the Z-axis coordinate value of the WGS84 coordinate system is zero.

4. The interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data according to claim 1 is characterized in that: The conversion of each satellite space coordinate into the latitude and longitude of the sub-satellite point includes the following implementation: Where X, Y, Z are the satellite space coordinates; Lon is the longitude of the sub-satellite point, Lat is the latitude of the sub-satellite point, H is the elevation; a is the major semi-axis of the earth ellipsoid in the WGS-84 coordinate system, b is the minor semi-axis of the earth ellipsoid in the WGS-84 coordinate system, e is the 2 is the first eccentricity, e' 2 is the second eccentricity, N is the radius of the yoke; Where B is the geodetic latitude.

5. The interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data according to claim 1 is characterized in that: The interpolation method for obtaining the longitude of the sub-satellite point at the equator includes: using the Lagrange interpolation method to interpolate the longitude information of the sub-satellite point before and after the Z-axis coordinate value is zero when the satellite descends or ascends, and solving the longitude of the sub-satellite point of the satellite at the equator.

6. The interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data according to claim 1 is characterized in that: The method of determining the longitudes of the sub-satellite points at the equator of all regression orbits in the satellite regression period according to the orbit distribution in the satellite regression period and using the longitude of the reference sub-satellite point at the equator of a single satellite orbit in the satellite regression period comprises: The sub-satellite longitudes of all regression orbits at the equator within a regression cycle are calculated through the regression cycles and the determined reference sub-satellite longitude of a single satellite orbit at the equator, and used as the reference orbit sub-satellite longitudes; The difference in longitude between adjacent regression orbits at the equator: Lon interval =360 / n Then the longitude of the sub-satellite point of the reference orbit within a regression period can be expressed as: Lon stand_pathi =Lon stand +i*Lon interval Where n is the total number of regression orbits in one regression cycle of the satellite, i is the number of regression orbits between the regression orbit and the determined reference sub-satellite point; if Lon stand_pathi >180, then Lon stand_pathi =Lon stand_pathi -360。 7. The method for monitoring sub-satellite point trajectory drift of heavy orbit interferometry SAR satellite based on analyzing satellite service data according to claim 1 is characterized in that: The method of determining the satellite orbit drift amount of each date in combination with the sub-satellite point longitude of the satellite orbit at the equator on each date includes: comparing the sub-satellite point longitude of each satellite orbit at the equator with the sub-satellite point longitude of the corresponding reference orbit to obtain the sub-satellite point track drift amount longitude difference, converting the drift amount longitude difference into the sub-satellite point track drift distance at the equator, and completing the sub-satellite point track drift monitoring; Where m is the number of satellite orbits involved in the calculation of satellite orbit ascending or descending in one day, and a is the major semi-axis of the Earth ellipsoid in the WGS-84 coordinate system.

8. An interferometric SAR satellite sub-satellite point trajectory drift monitoring device based on analyzing satellite service data, characterized in that: include: Memory, used to store computer programs; The processor is used to implement the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data as described in any one of claims 1-7 when executing the program stored in the memory.

9. A readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data according to any one of claims 1 to 7 is implemented.

10. A computer program product, characterized in that The computer program product includes: computer program code, which is loaded and executed by a computer to enable the computer to implement the interferometric SAR satellite sub-satellite point trajectory drift monitoring method based on analyzing satellite service data as described in any one of claims 1-7.

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