Water level measurement method and device based on LEO-IR

Abstract

The application relates to the technical field of navigation satellite reflection remote sensing, in particular to a water level measurement method and device based on LEO-IR, wherein the method comprises the following steps: acquiring LEO observation data and LEO broadcast ephemeris of a target water area adjacent to a shore-based LEO station; calculating angle information of a LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris and the actual position of the shore-based LEO station; calculating a reflection height and an accuracy attenuation factor of the reflection height according to the LEO observation data, the angle information and the LEO-IR; and calculating the water level height of the target water area based on the reflection height, the accuracy attenuation factor and the height of an antenna phase center. According to the application, more LEO satellites with higher moving speed are utilized to construct a time-consistent satellite arc-to-height rate error correction model and an accuracy attenuation factor model, so that the problem of low time resolution, low spatial resolution or low accuracy in the related art is solved, and the application has a significant application prospect and advantage in monitoring of water level fluctuation in extreme weather such as earthquake tsunamis and storm surges.

Description

Technical Field

[0001] The present application relates to the field of navigation satellite reflection remote sensing technology, and in particular to a water level measurement method and device based on LEO-IR. Background Art

[0002] Storm surges are abnormal sea level phenomena caused by cyclones, tropical storms or other strong wind weather systems. They have become one of the main causes of marine disasters in many coastal areas. Studies have shown that extreme sea level events can cause billions of dollars in economic losses worldwide each year and directly or indirectly affect hundreds of millions of coastal residents. In addition, with global warming, the risk of marine disasters such as storm surges is expected to continue to increase as the intensity of tropical cyclones continues to increase. Relevant models predict that by 2100, almost all coastal areas will experience an extreme sea level event that occurs once a century today every year. In order to mitigate the destructive effects of marine disasters such as storm surges, water level fluctuations caused by extreme events should be monitored as quickly and accurately as possible, because these water level fluctuation data will help model, predict and warn of water level anomalies.

[0003] In related technologies, water level measurement can be carried out through satellite altimetry, tide gauge stations or GNSS-IR (Global Navigation Satellite System Interferometric Reflectometry). Satellite altimetry uses an altimeter carried by an artificial earth satellite to measure the distance from the satellite to the instantaneous horizontal plane; a tide gauge station refers to a location where water level changes are recorded by setting a tide gauge or water gauge; and GNSS-IR can use the multipath effect of the positioning error source to sense the parameters of the signal reflection surface, and thus obtain the water level changes.

[0004] However, in related technologies, when short-term extreme events occur, due to the relatively long revisit period of satellite altimetry (or low temporal resolution) and the high risk of failure of tide gauges (such as power outages), they are unable to capture the complete waveform (or peak point). In addition, the sparse distribution of coastal tide gauges, high maintenance costs, and low accuracy of satellite altimetry for near-shore sea level monitoring further limit their ability to measure near-shore sea level. Due to the limitations of GNSS satellite constellation design, resulting in fewer satellite transits (i.e., a limited number of GNSS-IR solutions) and slower movement relative to the earth (i.e., a long time required for a single GNSS-IR solution), the temporal resolution and accuracy of GNSS-IR are fundamentally limited and cannot fully meet the requirements for monitoring water level fluctuations caused by short-term extreme events, and are in urgent need of improvement. Summary of the Invention

[0005] The present application provides a water level measurement method and device based on LEO-IR to solve the problem in related technologies that, due to the low temporal resolution, spatial resolution or accuracy of satellite altimetry, tide gauges, GNSS-IR, etc., it is impossible to fully meet the requirements for monitoring water level fluctuations caused by short-term extreme events when short-term extreme events occur.

[0006] The first aspect of the present application provides a water level measurement method based on LEO-IR, including the following steps: obtaining LEO observation data and LEO broadcast ephemeris of a shore-based LEO (Low Earth Orbit) station adjacent to a target water area; calculating the angle information of the LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris and the actual position of the shore-based LEO station; calculating the reflection height between the antenna phase center of the shore-based LEO station and the near-coastal horizontal plane of the target water area and the precision attenuation factor of the reflection height based on the LEO observation data, the angle information and LEO-IR; and calculating the water level height of the target water area based on the reflection height, the precision attenuation factor and the height of the antenna phase center.

[0007] Optionally, in one embodiment of the present application, the calculating the reflection height between the phase center of the shore-based LEO station antenna and the near-coastal horizontal plane of the target water area and the precision dilution factor of the reflection height based on the LEO observation data, the angle information and the LEO-IR includes: obtaining a time-consistent satellite arc-to-altitude rate error correction model in the LEO-IR; obtaining a precision dilution factor model in the LEO-IR; and calculating the reflection height and the precision dilution factor based on the LEO observation data and the angle information in combination with the time-consistent satellite arc-to-altitude rate error correction model and the precision dilution factor model.

[0008] Optionally, in one embodiment of the present application, the calculation of the reflection height between the phase center of the shore-based LEO station antenna and the near-coastal horizontal plane of the target waters and the precision attenuation factor of the reflection height based on the LEO observation data, the angle information and the LEO-IR includes: calculating the first Fresnel reflection area of ​​the shore-based LEO station based on the prior rough reflection height of the shore-based LEO station; using the first Fresnel reflection area to filter the angle information to obtain the available range of the elevation angle and the azimuth angle in the angle information; extracting the available LEO observation data and the available angle information that meet the available range from the LEO observation data and the angle information; and calculating the satellite arc segment of the LEO satellite corresponding to the shore-based LEO station based on the satellite arc segment of the LEO satellite corresponding to the shore-based LEO station. The method comprises the following steps: dividing the available LEO observation data and the available angle information according to a time threshold and an altitude angle change rate to obtain an initial monotonic satellite arc segment of the available LEO observation data and the available angle information; calculating the intermediate moment of the initial monotonic satellite arc segment, the initial reflection height between the phase center of the shore-based LEO station antenna and the near-shore horizontal plane of the target water area according to the initial monotonic satellite arc segment; obtaining a satellite arc pair that meets a preset time condition based on the initial monotonic satellite arc segment and the intermediate moment; and calculating the reflection height and the dilution of precision factor based on the initial reflection height, the initial altitude angle, and the initial altitude angle change rate in combination with the time-consistent satellite arc pair altitude rate error correction model and the dilution of precision factor model.

[0009] Optionally, in one embodiment of the present application, the expression of the time-consistent satellite arc-to-altitude rate error correction model may be, but is not limited to,:

[0010] Bx=L

[0011]

[0012] Wherein, the subscripts sat1 and sat2 denote a pair of time-coherent satellite arcs; represents the initial reflection height; el and eldot represent the altitude angle and altitude angle change rate respectively; h and They represent the reflection height and its rate of change respectively; x represents the system state vector; L represents the observation vector; B represents the design matrix connecting the observation vector and the system state vector.

[0013] Optionally, in one embodiment of the present application, the expression of the DOP model may be, but is not limited to,:

[0014]

[0015] Among them, Q 2×2 is a 2×2 square matrix; Q 11 and Q 22 Represents Q2×2 the elements at the first column of the first row and the second column of the second row in the matrix; hDOP, and respectively represent the accuracy attenuation factor values of h, and the combination of both.

[0016] The second aspect embodiment of the present application provides a water level measuring device based on LEO-IR, comprising: an acquisition module, configured to acquire LEO observation data and LEO broadcast ephemeris of a target water area adjacent to a shore-based LEO station; a first calculation module, configured to calculate angle information of a LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris and an actual position of the shore-based LEO station; a second calculation module, configured to calculate a reflection height between an antenna phase center of the shore-based LEO station and a near-shore horizontal plane of the target water area and an accuracy attenuation factor of the reflection height according to the LEO observation data, the angle information and LEO-IR; and a third calculation module, configured to calculate a water level height of the target water area based on the reflection height, the accuracy attenuation factor and a height of the antenna phase center.

[0017] Optionally, in an embodiment of the present application, the second calculation module comprises: a first acquisition unit, configured to acquire a time-consistent satellite arc pair height rate error correction model in the LEO-IR; a second acquisition unit, configured to acquire an accuracy attenuation factor model in the LEO-IR; and a calculation unit, configured to calculate the reflection height and the accuracy attenuation factor according to the LEO observation data and the angle information, in combination with the time-consistent satellite arc pair height rate error correction model and the accuracy attenuation factor model.

[0018] Optionally, in an embodiment of the present application, the computing unit comprises: a first computing subunit configured to calculate a first Fresnel reflection zone of the shore-based LEO station based on a prior coarse reflection height of the shore-based LEO station; a first generating subunit configured to filter the angle information using the first Fresnel reflection zone to obtain available intervals of elevation angle and azimuth angle in the angle information; an extracting unit configured to extract available LEO observation data and available angle information in the LEO observation data and the angle information that meet the available intervals; a second generating subunit configured to divide the available LEO observation data and the available angle information based on a satellite arc segment time threshold and an elevation angle change rate of a corresponding LEO satellite of the shore-based LEO station to obtain an initial monotonic satellite arc segment of the available LEO observation data and the available angle information; a second computing subunit configured to calculate an initial reflection height between an antenna phase center of the shore-based LEO station and a near-shore horizontal plane of the target water area at a middle time of the initial monotonic satellite arc segment according to the initial monotonic satellite arc segment; a third computing subunit configured to obtain a satellite arc pair that meets a preset time condition based on the initial monotonic satellite arc segment and the middle time; a third generating subunit configured to obtain an initial elevation angle and an initial elevation angle change rate of the monotonic satellite arc segment at the middle time based on the middle time; and a fourth computing subunit configured to calculate the reflection height and the precision decay factor based on the initial reflection height, the initial elevation angle, and the initial elevation angle change rate, in combination with the time-consistent satellite arc pair height rate error correction model and the precision decay factor model.

[0019] Optionally, in an embodiment of the present application, the expression of the time-consistent satellite arc pair height rate error correction model can be but is not limited to:

[0020] Bx = L

[0021]

[0022] wherein, the subscripts sat1 and sat2 represent time-consistent satellite arc pairs; represents a preliminary reflection height; el and eldot represent an elevation angle and an elevation angle change rate, respectively; h and hdot represent a reflection height and a change rate thereof, respectively; x represents a system state vector; L represents an observation vector; and B represents a design matrix connecting the observation vector and the system state vector.

[0023] Optionally, in an embodiment of the present application, the expression of the precision decay factor model can be but is not limited to:

[0024]

[0025] wherein, Q 2×2 ​is a 2×2 square matrix; Q 11 and Q 22 Represents Q 2×2 The element at the first row, first column and second row, second column in the matrix; hDOP, and Respectively represent h, and the DOP value of both combined.

[0026] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the LEO-IR-based water level measurement method as described in the above embodiment.

[0027] A fourth aspect of the present application provides a computer-readable storage medium, which stores a computer program. When the program is executed by a processor, it implements the above-mentioned LEO-IR-based water level measurement method.

[0028] The fifth aspect of the present application provides a computer program product, including a computer program, which implements the above-mentioned LEO-IR-based water level measurement method when executed.

[0029] The embodiment of the present application can calculate the angle information of the LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris obtained by the shore-based LEO station near the target water area and the actual position of the shore-based LEO station, and then calculate the reflection height and the precision attenuation factor of the reflection height between the phase center of the shore-based LEO station antenna and the near-coastal horizontal plane of the target water area based on the LEO observation data and angle information and LEO-IR obtained by the shore-based LEO station, and then calculate the water level of the target water area, thereby improving the time resolution, spatial resolution and accuracy of the water level of the target water area, and it is relatively simple to implement. Therefore, it solves the problem in the related art that due to the low time resolution or spatial resolution or accuracy of satellite altimetry, tide gauge stations, GNSS-IR, etc., when short-term extreme events occur, it is impossible to fully meet the requirements for monitoring water level fluctuations caused by short-term extreme events.

[0030] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0032] Figure 1 This is a flow chart of a water level measurement method based on LEO-IR according to an embodiment of the present application;

[0033] Figure 2 A flowchart of calculating angle information according to one embodiment of the present application is provided;

[0034] Figure 3 A flowchart of calculating reflection height and its precision reduction factor according to one embodiment of the present application is provided;

[0035] Figure 4 This is a flow chart of the working principle of a water level measurement method based on LEO-IR according to one embodiment of the present application;

[0036] Figure 5 Schematic diagram of a LEO-IR-based water level measurement device according to an embodiment of the present application;

[0037] Figure 6 A schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0039] The following describes a water level measurement method and device based on LEO-IR in an embodiment of the present application with reference to the accompanying drawings. In response to the problem mentioned in the above background technology that the time resolution, spatial resolution or accuracy of satellite altimetry, tide gauge stations, GNSS-IR, etc. is low, resulting in the inability to fully meet the requirements for monitoring water level fluctuations caused by short-term extreme events when short-term extreme events occur, the present application provides a water level measurement method based on LEO-IR, in which the angle information of the LEO satellite relative to the shore-based LEO station can be calculated based on the LEO broadcast ephemeris obtained by the shore-based LEO station near the target water area and the actual position of the shore-based LEO station, and then the reflection height between the shore-based LEO station antenna phase center and the near-coast horizontal plane of the target water area and the precision attenuation factor of the reflection height are calculated based on the LEO observation data and angle information obtained by the shore-based LEO station and the LEO-IR, and then the water level of the target water area is calculated, thereby improving the time resolution, spatial resolution and accuracy of the water level of the target water area, and being relatively simple to implement. This solves the problem in related technologies that, due to the low temporal resolution, spatial resolution or accuracy of satellite altimetry, tide gauges, GNSS-IR, etc., they are unable to fully meet the requirements for monitoring water level fluctuations caused by short-term extreme events when they occur.

[0040] Specifically, Figure 1 The present invention provides a flow chart of a water level measurement method based on LEO-IR according to an embodiment of the present application.

[0041] like Figure 1 As shown, the water level measurement method based on LEO-IR includes the following steps:

[0042] In step S101, LEO observation data and LEO broadcast ephemeris of a shore-based LEO station adjacent to the target waters are obtained.

[0043] It is understandable that, from the perspective of data sources, the embodiments of the present application use shore-based LEO stations adjacent to the target waters to obtain LEO observation data and LEO broadcast ephemeris for the target waters. Compared to GNSS medium- and high-orbit navigation satellites, LEO satellites move faster relative to the Earth (approximately 30 times faster), and a complete LEO constellation typically has a larger number of satellites.

[0044] As a possible implementation method, the shore-based LEO station near the target waters of the embodiment of the present application can collect LEO observation data and LEO broadcast ephemeris broadcast by LEO satellites in real time, and send the collected LEO observation data and LEO broadcast ephemeris to the ground computing center.

[0045] In the embodiment of the present application, LEO observation data may include, but is not limited to, signal-to-noise ratio and signal strength indicators, etc., and this application does not impose specific restrictions.

[0046] In addition, it should be noted that, in the embodiments of the present application, proximity can be understood as being within a certain range from the target water area, which can be specifically set by technicians in this field according to actual conditions, and this application does not impose any specific restrictions.

[0047] In step S102, the angle information of the LEO satellite relative to the shore-based LEO station is calculated based on the LEO broadcast ephemeris and the actual position of the shore-based LEO station.

[0048] It can be understood that in the embodiment of the present application, the angle information may include but is not limited to azimuth, altitude, altitude change rate, etc., and the present application does not impose any specific restrictions.

[0049] As a possible implementation method, the embodiment of the present application can calculate the angle information of the LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris and the actual position of the locally stored shore-based LEO station.

[0050] For example, the process of calculating the angle information in the embodiment of the present application is as follows: Figure 2 As shown, the main contents are:

[0051] Step S201: Calculate the Earth-centered Earth-fixed coordinates of the LEO satellite based on the LEO broadcast ephemeris.

[0052] Among them, in the field of satellite navigation and positioning, the embodiment of the present application calculates the Earth-centered Earth-fixed coordinates of the satellite based on the satellite broadcast ephemeris elements, which is a classic and mature method and will not be elaborated in this application.

[0053] Step S202: Calculate the station-centered coordinate system coordinates of the LEO satellite based on the Earth-centered Earth-fixed coordinates of the LEO satellite and the position coordinates of the actual position of the locally stored shore-based LEO station.

[0054] In the embodiment of the present application, the station center coordinate system takes the shore-based LEO station as the coordinate origin.

[0055] Step S203: Calculate the angle information of the LEO satellite relative to the shore-based LEO station based on the station center coordinate system coordinates of the LEO satellite.

[0056] The angle information in the embodiment of the present application may include, but is not limited to, azimuth, altitude, altitude change rate, etc., and the present application does not impose any specific restrictions. The calculation formula may be, but is not limited to:

[0057]

[0058] Where (e(t), n(t), u(t)) represents the coordinates of the LEO satellite in the station center coordinate system at epoch t; t s represents a small amount of time, which can generally be taken as 0.001 seconds; az(t), el(t) and eldot(t) respectively represent the azimuth, altitude and rate of change of the altitude of the LEO satellite relative to the shore-based LEO station at epoch t; arcsin and arctan represent inverse sine and inverse tangent operations respectively.

[0059] In step S103, the reflection height between the phase center of the shore-based LEO station antenna and the near-shore horizontal plane of the target water area and the dilution of precision factor of the reflection height are calculated based on the LEO observation data, angle information and LEO-IR.

[0060] As a possible implementation method, the embodiment of the present application can calculate the reflection height and precision attenuation factor between the antenna phase center of the shore-based LEO station and the near-coastal horizontal plane of the target water area based on LEO observation data and angle information based on LEO-IR.

[0061] Optionally, in one embodiment of the present application, the reflection height and the dilution of precision of the reflection height between the phase center of the shore-based LEO station antenna and the near-shore horizontal plane of the target water area are calculated based on LEO observation data and angle information and LEO-IR, including: obtaining a time-consistent satellite arc-to-altitude rate error correction model in the LEO-IR; obtaining a dilution of precision model in the LEO-IR; and calculating the reflection height and the dilution of precision based on the LEO observation data and angle information in combination with the time-consistent satellite arc-to-altitude rate error correction model and the dilution of precision model. The expression of the time-consistent satellite arc-to-altitude rate error correction model can be, but is not limited to,:

[0062] Bx=L

[0063]

[0064] Wherein, the subscripts sat1 and sat2 denote a pair of time-coherent satellite arcs; represents the initial reflection height; el and eldot represent the altitude angle and altitude angle change rate respectively; h and They represent the reflection height and its rate of change respectively; x represents the system state vector; L represents the observation vector; B represents the design matrix connecting the observation vector and the system state vector.

[0065] The expression of the DOP model can be, but is not limited to:

[0066]

[0067] Among them, Q 2×2 is a 2×2 square matrix; Q 11 and Q 22 Represents Q 2×2 The element at the first row, first column and second row, second column in the matrix; hDOP, and Respectively represent h, and the DOP value of both combined.

[0068] In some embodiments, the embodiments of the present application can utilize a larger number of LEO satellites with faster movement speeds to construct a time-consistent satellite arc pair altitude rate error correction model based on time-consistent satellite arc pairs. The expression of the time-consistent satellite arc pair altitude rate error correction model can be, but is not limited to,:

[0069] Bx=L

[0070]

[0071] Wherein, the subscripts sat1 and sat2 denote a pair of time-coherent satellite arcs; represents the initial reflection height; el and eldot represent the altitude angle and altitude angle change rate respectively; h and where represents the reflection height and its rate of change, respectively; x represents the system state vector; L represents the observation vector; and B represents the design matrix connecting the observation vector and the system state vector. This model exploits the relationship that "the change rate of reflection height for time-aligned satellite arc pairs is consistent" to cleverly correct for highly random height rate errors. This model, without smoothing assumptions, is suitable for monitoring nearshore water level fluctuations in extreme ocean events.

[0072] In some embodiments, the present application can establish a DOP to evaluate the effect of the altitude rate error correction, thereby quantitatively describing the accuracy of the LEO-IR altitude measurement results. The expression of the DOP model can be, but is not limited to,:

[0073]

[0074] Among them, Q 2×2 is a 2×2 square matrix; Q 11 and Q 22 Represents Q 2×2 The element at the first row, first column and second row, second column in the matrix; hDOP, and Respectively represent h, The larger the value of these evaluation factors, the greater the magnification of the observation error in the process of height rate error correction, and the less ideal the height rate error correction effect.

[0075] Optionally, in one embodiment of the present application, the reflection height and the precision dilution factor are calculated based on the LEO observation data and angle information, combined with the time-consistent satellite arc-to-altitude rate error correction model and the precision dilution factor model, including: calculating the first Fresnel reflection area of ​​the shore-based LEO station based on the prior rough reflection height of the shore-based LEO station; using the first Fresnel reflection area to filter the angle information to obtain the available range of the altitude angle and azimuth angle in the angle information; extracting the available LEO observation data and available angle information that meet the available range in the LEO observation data and angle information; and extracting the satellite arc segment time threshold of the shore-based LEO station corresponding to the LEO satellite based on the satellite arc segment time threshold of the shore-based LEO station corresponding to the LEO satellite. The available LEO observation data and available angle information are divided according to the value and altitude angle change rate to obtain the initial monotonic satellite arc segment of the available LEO observation data and available angle information; the intermediate moment of the initial monotonic satellite arc segment, the initial reflection height between the phase center of the shore-based LEO station antenna and the near-coastal horizontal plane of the target water area are calculated according to the initial monotonic satellite arc segment; the satellite arc pair that meets the preset time condition is obtained based on the initial monotonic satellite arc segment and the intermediate moment; the reflection height and precision dilution factor are calculated based on the initial reflection height, initial altitude angle, and initial altitude angle change rate, combined with the time-consistent satellite arc pair altitude rate error correction model and the precision dilution factor model.

[0076] As a possible implementation method, the embodiment of the present application calculates the reflection height and its precision reduction factor between the phase center of the shore-based LEO station antenna and the horizontal plane near the coast of the target water area based on LEO observation data and angle information. The process is as follows: Figure 3 As shown, including the following:

[0077] Step S301: Based on the prior rough reflection height of the shore-based LEO station, the first Fresnel reflection area of ​​the shore-based LEO station is calculated, and the angle information is filtered using the first Fresnel reflection area to obtain the available ranges of the elevation angle and azimuth angle.

[0078] Among them, the prior rough reflection height of the embodiment of the present application can be determined based on prior knowledge. When the reflecting surface is a near-coastal horizontal plane, the prior knowledge is generally the average height of the near-coastal horizontal plane and the antenna phase center height of the shore-based LEO station.

[0079] In addition, in the embodiment of the present application, the boundary of the first Fresnel reflection zone is an ellipse, and its calculation formula can be but is not limited to:

[0080]

[0081] Where (x0, y0) represents the coordinates of the center of the ellipse in a plane rectangular coordinate system with the shore-based LEO station as the origin and the LEO satellite ground projection direction as the positive direction of the y-axis; a and b represent the major and minor semi-axes of the ellipse, respectively; h rrepresents the prior rough reflection height; λ represents the carrier wavelength; el represents the elevation angle of the LEO satellite relative to the shore-based LEO station; sin and cot represent sine and cotangent operations, respectively.

[0082] In addition, it should be noted that the embodiment of the present application can use the XX tool to screen the available altitude angles and azimuth angles so that the first Fresnel reflection area falls completely within the reflection area. The first Fresnel reflection area should be as far away from the land as possible and fall completely into the water.

[0083] Step S302: extracting available LEO observation data and available angle information from the LEO observation data and angle information according to the available intervals of the altitude angle and the azimuth angle.

[0084] Step S303: Segment the available LEO observation data and available angle information into initial monotonic satellite arc segments according to the satellite arc segment time threshold and the altitude angle change rate.

[0085] It can be understood that the initial monotonic satellite arc segment can be understood as a monotonically rising or falling satellite arc segment, which can be specifically set by technicians in this field according to actual conditions, and this application does not impose any specific restrictions.

[0086] For example, the embodiment of the present application can first be segmented according to the satellite arc time threshold, and then segmented according to the altitude angle change rate. Among them, the embodiment of the present application can set the satellite arc time threshold to 5 minutes, and segmentation is performed if it exceeds this threshold; the altitude angle change rate is divided into two cases, increasing and decreasing, and segmentation is performed if the situation of the previous and next consecutive epochs changes. The specific settings can be made by technicians in this field according to actual conditions, and this application does not impose any specific restrictions.

[0087] Step S304: Calculate the middle time and initial reflection height of the initial monotonic satellite arc segment according to the initial monotonic satellite arc segment.

[0088] It can be understood that the middle time in the embodiment of the present application can be understood as the average of the start time and the end time of the satellite arc segment. It can be specifically set by technicians in this field according to actual conditions, and this application does not impose any specific restrictions.

[0089] In addition, it should be noted that the embodiment of the present application can use a spectral analysis mathematical model to calculate the initial reflection height, and the calculation formula can be but is not limited to:

[0090]

[0091] Where λ represents the carrier wavelength; represents the initial reflection height; Indicates the maximum dominant frequency extracted from the SNR or signal strength indicator oscillation sequence using the LSP method.

[0092] Step S305: Obtain satellite arc pairs that meet certain time conditions based on the initial monotonic satellite arc segments and intermediate moments.

[0093] In this embodiment, the present application can match time-consistent satellite arc pairs based on the time threshold for time-consistent satellite arc pairs and the mid-point of the satellite arc segment, thereby obtaining monotonic satellite arc pairs that meet certain time conditions. The certain time conditions can be set by those skilled in the art based on actual circumstances and are not specifically limited in this application.

[0094] Furthermore, in an embodiment of the present application, when the absolute value of the difference between the intermediate moments of the two satellite arc segments is smaller than the time threshold of the time-consistent satellite arc pair, the two satellite arc segments are successfully matched into a time-consistent satellite arc pair; the time threshold of the time-consistent satellite arc pair can be set to 1 minute, and this application does not impose any specific restrictions.

[0095] Step S306: Based on the initial reflection height of the satellite arc pair, the initial altitude angle at the middle of the initial monotonic satellite arc segment and the rate of change of the initial altitude angle, combined with LEO-IR, the reflection height and the dilution of precision factor are calculated.

[0096] Among them, the embodiment of the present application can calculate the reflection height based on the time-consistent satellite arc height rate error correction model, evaluate the correction effect of the height rate error through the established precision attenuation factor model, and thus quantitatively describe the accuracy of the height measurement results.

[0097] In step S104 , the water level of the target water area is calculated based on the reflection height, the dilution of precision, and the height of the antenna phase center.

[0098] During actual implementation, the embodiment of the present application can calculate the water level height near the coastal horizontal plane based on the reflection height, the precision attenuation factor and the height of the antenna phase center, and send the water level height to the early warning center.

[0099] Among them, the height of the phase center of the shore-based LEO station antenna in the embodiment of the present application can be accurately measured by leveling measurement, or determined by GNSS precise positioning means, such as precise single-point positioning or relative positioning, etc., which can be specifically set by technicians in this field according to actual conditions, and this application does not impose any specific restrictions.

[0100] The working principle of the water level measurement method based on LEO-IR proposed in the embodiment of the present application is introduced below with reference to a specific embodiment.

[0101] in, Figure 4 The figure is a flow chart of the working principle of the water level measurement method based on LEO-IR according to one embodiment of the present application.

[0102] Step S401: The shore-based LEO station collects LEO observation data and LEO broadcast ephemeris broadcast by the LEO satellite in real time, and sends the collected LEO observation data and LEO broadcast ephemeris to the ground computing center.

[0103] Step S402: The ground computing center calculates the angle information of the LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris and the actual position of the shore-based LEO station stored locally.

[0104] Step S403: The ground computing center calculates the reflection height and its derating factor between the antenna phase center of the shore-based LEO station and the near-coastal horizontal plane of the target waters based on the LEO observation data and angle information and LEO-IR.

[0105] Step S404: The ground computing center calculates the water level of the near-shore horizontal plane based on the reflection height, the dilution of precision factor, and the height of the antenna phase center, and sends the water level to the early warning center.

[0106] According to the water level measurement method based on LEO-IR proposed in the embodiment of the present application, the angle information of the LEO satellite relative to the shore-based LEO station can be calculated based on the LEO broadcast ephemeris obtained by the shore-based LEO station near the target water area and the actual position of the shore-based LEO station, and then the reflection height and the precision attenuation factor of the reflection height between the phase center of the shore-based LEO station antenna and the near-coastal horizontal plane of the target water area are calculated based on the LEO observation data and angle information obtained by the shore-based LEO station and LEO-IR, and then the water level of the target water area is calculated, thereby improving the time resolution, spatial resolution and accuracy of the water level of the target water area, and it is relatively simple to implement. Therefore, the problem in the related technology that the time resolution, spatial resolution or accuracy of satellite altimetry, tide gauge stations, GNSS-IR, etc. are low, resulting in the inability to fully meet the requirements for monitoring water level fluctuations caused by short-term extreme events when short-term extreme events occur is solved.

[0107] Next, a LEO-IR-based water level measuring device according to an embodiment of the present application will be described with reference to the accompanying drawings.

[0108] Figure 5 Schematic diagram of a block diagram of a LEO-IR-based water level measurement device according to an embodiment of the present application.

[0109] like Figure 5 As shown, the LEO-IR-based water level measurement device 50 includes: an acquisition module 100 , a first calculation module 200 , a second calculation module 300 and a third calculation module 400 .

[0110] The acquisition module 100 is used to acquire LEO observation data and LEO broadcast ephemeris of a shore-based LEO station adjacent to the target waters.

[0111] The first calculation module 200 is configured to calculate the angle information of the LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris and the actual position of the shore-based LEO station.

[0112] The second calculation module 300 is used to calculate the reflection height and the dilution of precision factor of the reflection height between the phase center of the shore-based LEO station antenna and the near-shore horizontal plane of the target water area based on the LEO observation data, angle information and LEO-IR.

[0113] The third calculation module 400 is configured to calculate the water level height near the coast based on the reflection height, the dilution of precision, and the height of the antenna phase center.

[0114] Optionally, in one embodiment of the present application, the second calculation module 300 includes: a first acquisition unit, a second acquisition unit and a first calculation unit.

[0115] The first acquisition unit is used to obtain a time-consistent satellite arc-to-altitude rate error correction model in LEO-IR.

[0116] The second acquisition unit is used to acquire a dilution of precision model in the LEO-IR.

[0117] The first calculation unit is used to calculate the reflection height and the precision dilution factor based on the LEO observation data and angle information in combination with the time-consistent satellite arc-to-height rate error correction model and the precision dilution factor model.

[0118] Optionally, in one embodiment of the present application, the second computing module 300 includes: a first computing subunit, a first generating subunit, an extracting unit, a second generating subunit, a second computing subunit, a third computing subunit, a third generating subunit and a fourth computing subunit.

[0119] The first calculation subunit is used to calculate the first Fresnel reflection area of ​​the shore-based LEO station based on the prior rough reflection height of the shore-based LEO station.

[0120] The first generating subunit is configured to filter the angle information by using the first Fresnel reflection zone to obtain available ranges of the altitude angle and the azimuth angle in the angle information.

[0121] The extraction unit is used to extract the available LEO observation data and available angle information that meet the available interval from the LEO observation data and angle information.

[0122] The second generating subunit is configured to segment the available LEO observation data and the available angle information based on the satellite arc segment time threshold and the elevation angle change rate of the LEO satellite corresponding to the shore-based LEO station, so as to obtain an initial monotonic satellite arc segment of the available LEO observation data and the available angle information.

[0123] The second calculating subunit is configured to calculate an initial reflection height between the antenna phase center of the shore-based LEO station and the near-shore horizontal plane of the target water area according to the intermediate time of the initial monotonic satellite arc segment.

[0124] The third calculating subunit is configured to obtain a satellite arc pair satisfying a preset time condition based on the initial monotonic satellite arc segment and the intermediate time.

[0125] The third generating subunit is configured to obtain an initial elevation angle and an initial elevation angle change rate of the monotonic satellite arc segment at the intermediate time based on the intermediate time.

[0126] The fourth calculating subunit is configured to calculate the reflection height and the precision decay factor based on the initial launch height, the initial elevation angle and the initial elevation angle change rate, and in combination with the LEO-IR.

[0127] Optionally, in an embodiment of the present application, the expression of the time-consistent satellite arc pair height rate error correction model can be but is not limited to:

[0128] Bx=L

[0129]

[0130] wherein the subscripts sat1 and sat2 represent the time-consistent satellite arc pair; represents the preliminary reflection height; el and eldot represent the elevation angle and the elevation angle change rate, respectively; h and hdot represent the reflection height and the change rate thereof, respectively; x represents the system state vector; L represents the observation vector; and B represents the design matrix connecting the observation vector and the system state vector.

[0131] Optionally, in an embodiment of the present application, the expression of the precision decay factor model can be but is not limited to:

[0132]

[0133] wherein Q 2×2 is a 2x2 matrix; Q 11 and Q 22 represent the elements at the first row and the first column and the second row and the second column of the Q 2×2 matrix, respectively; hDOP, and represent the precision decay factor values of the h, and the combination thereof, respectively.​

[0134] It should be noted that the aforementioned explanation of the embodiment of the water level measurement method based on LEO-IR is also applicable to the water level measurement device based on LEO-IR in this embodiment, and will not be repeated here.

[0135] According to the LEO-IR-based water level measurement device proposed in the embodiment of the present application, the angle information of the LEO satellite relative to the shore-based LEO station can be calculated based on the LEO broadcast ephemeris obtained by the shore-based LEO station near the target water area and the actual position of the shore-based LEO station, and then the reflection height and the precision attenuation factor of the reflection height between the phase center of the shore-based LEO station antenna and the near-coastal horizontal plane of the target water area are calculated based on the LEO observation data and angle information obtained by the shore-based LEO station and LEO-IR, and then the water level of the target water area is calculated, thereby improving the time resolution, spatial resolution and accuracy of the water level of the target water area, and it is relatively simple to implement. Therefore, the problem in the related technology that the time resolution, spatial resolution or accuracy of satellite altimetry, tide gauge stations, GNSS-IR, etc. are low, resulting in the inability to fully meet the requirements for monitoring water level fluctuations caused by short-term extreme events when short-term extreme events occur is solved.

[0136] Figure 6 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. The electronic device may include:

[0137] A memory 601 , a processor 602 , and a computer program stored in the memory 601 and executable on the processor 602 .

[0138] When the processor 602 executes the program, the LEO-IR-based water level measurement method provided in the above embodiment is implemented.

[0139] Furthermore, the electronic device further includes:

[0140] The communication interface 603 is used for communication between the memory 601 and the processor 602 .

[0141] The memory 601 is used to store computer programs that can be run on the processor 602 .

[0142] The memory 601 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0143] If the memory 601, processor 602, and communication interface 603 are implemented independently, the communication interface 603, memory 601, and processor 602 can be interconnected via a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 6 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0144] Optionally, in a specific implementation, if the memory 601, the processor 602 and the communication interface 603 are integrated on a chip, the memory 601, the processor 602 and the communication interface 603 can communicate with each other through an internal interface.

[0145] The processor 602 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0146] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned LEO-IR-based water level measurement method.

[0147] An embodiment of the present application further provides a computer program product, including a computer program, which implements the above-mentioned LEO-IR-based water level measurement method when executed.

[0148] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0149] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0150] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing a custom logical function or process step, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed in a different order than shown or discussed, including performing functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0151] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or N wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program can be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing it in other suitable ways as necessary, and then storing it in a computer memory.

[0152] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented using hardware, as in another embodiment, it can be implemented using any one or a combination of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0153] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0154] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0155] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application. Persons skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A water level measurement method based on LEO-IR, characterized in that: The following steps are involved: Obtain LEO observation data and LEO broadcast ephemeris from shore-based LEO stations near the target waters; Calculating angle information of the LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris and the actual position of the shore-based LEO station; Calculate the reflection height between the phase center of the shore-based LEO station antenna and the near-shore horizontal plane of the target waters and the dilution of precision factor of the reflection height based on the LEO observation data, the angle information and the LEO-IR; Calculating the water level of the target water area based on the reflection height, the dilution of precision factor, and the height of the antenna phase center; The calculating, based on the LEO observation data, the angle information, and the LEO-IR, of the reflection height between the phase center of the shore-based LEO station antenna and the near-shore horizontal plane of the target waters and the dilution of precision factor of the reflection height includes: Obtaining a time-consistent satellite arc-to-altitude rate error correction model in the LEO-IR; Obtaining a dilution of precision model in the LEO-IR; Calculating the reflection height and the dilution of precision based on the LEO observation data and the angle information in combination with the time-consistent satellite arc-to-altitude rate error correction model and the dilution of precision model; The expression of the time-consistent satellite arc to altitude rate error correction model is: ， Among them, the subscript and represents a pair of time-coherent satellite arcs; Indicates the initial reflection height; and denote the altitude angle and altitude angle change rate respectively; and Represent the reflection height and its changing rate respectively; represents the system state vector; represents the observation vector; represents the design matrix connecting the observation vector and the system state vector; The expression of the precision reduction factor model is: ， in, for phalanx; and Respectively The elements at the first row and first column and the second row and second column in the matrix; 、 and Respectively 、 and the DOP value of both combined.

2. The method according to claim 1, characterized in that Calculating the reflection height and the dilution of precision factor based on the LEO observation data and the angle information in combination with the time-consistent satellite arc-to-altitude rate error correction model and the dilution of precision factor model includes: Calculating a first Fresnel reflection zone of the shore-based LEO station based on a priori rough reflection height of the shore-based LEO station; Filtering the angle information using the first Fresnel reflection zone to obtain usable ranges of the altitude angle and the azimuth angle in the angle information; Extracting available LEO observation data and available angle information that meet the available interval from the LEO observation data and the angle information; Segmenting the available LEO observation data and the available angle information based on a satellite arc time threshold and an altitude angle change rate of the LEO satellite corresponding to the shore-based LEO station to obtain an initial monotonic satellite arc of the available LEO observation data and the available angle information; Calculating, based on the initial monotonic satellite arc, the middle moment of the initial monotonic satellite arc, the initial reflection height between the phase center of the shore-based LEO station antenna and the near-coastal horizontal plane of the target waters; Obtaining a satellite arc pair that meets a preset time condition based on the initial monotonic satellite arc segment and the intermediate time; Obtaining, based on the intermediate moment, an initial elevation angle and an initial elevation angle change rate of the monotonic satellite arc segment at the intermediate moment; The reflection height and the dilution of precision factor are calculated based on the initial reflection height, the initial altitude angle, and the rate of change of the initial altitude angle in combination with the time-consistent satellite arc-to-altitude rate error correction model and the dilution of precision factor model.

3. A water level measuring device based on LEO-IR, characterized in that: include: An acquisition module is used to obtain LEO observation data and LEO broadcast ephemeris of the shore-based LEO stations near the target waters; a first calculation module, configured to calculate angle information of the LEO satellite relative to the shore-based LEO station based on the LEO broadcast ephemeris and the actual position of the shore-based LEO station; A second calculation module is used to calculate the reflection height between the phase center of the shore-based LEO station antenna and the near-shore horizontal plane of the target water area and the precision dilution factor of the reflection height based on the LEO observation data, the angle information and the LEO-IR; a third calculation module, configured to calculate the water level of the target water area based on the reflection height, the dilution of precision factor, and the height of the antenna phase center; The second calculation module includes: A first acquisition unit is configured to acquire a time-consistent satellite arc-to-altitude rate error correction model in the LEO-IR; A second acquiring unit is configured to acquire a dilution of precision model in the LEO-IR; a first calculation unit, configured to calculate the reflection height and the dilution of precision based on the LEO observation data and the angle information in combination with the time-consistent satellite arc-to-altitude rate error correction model and the dilution of precision model; The expression of the time-consistent satellite arc to altitude rate error correction model is: ， Among them, the subscript and represents a pair of time-coherent satellite arcs; Indicates the initial reflection height; and They represent the altitude angle and the rate of change of altitude angle respectively; and Represent the reflection height and its changing rate respectively; represents the system state vector; represents the observation vector; represents the design matrix connecting the observation vector and the system state vector; The expression of the precision reduction factor model is: ， in, for phalanx; and Respectively The elements at the first row and first column and the second row and second column in the matrix; 、 and Respectively 、 and the DOP value of both combined.

4. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the LEO-IR-based water level measurement method according to any one of claims 1 to 2.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the LEO-IR-based water level measurement method according to any one of claims 1 to 2.

6. A computer program product, characterized in that The invention comprises a computer program, which, when executed, is used to implement the water level measurement method based on LEO-IR according to any one of claims 1 to 2.

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