LEO-IR-based water level measurement method and device

Abstract

The invention 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, and the method comprises the steps: obtaining LEO observation data and LEO broadcast ephemeris of a shore-based LEO station adjacent to a target water area; 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; calculating a reflection height and a precision attenuation factor of the reflection height according to LEO observation data, 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. According to the embodiment of the invention, the method employs a larger number of LEO satellites with a higher moving speed to construct a time-consistent satellite arc-to-height rate error correction model and a precision attenuation factor model, solves a problem that the time resolution or spatial resolution or precision is lower in the related technology, and improves the accuracy of the satellite arc-to-height rate error correction model. The method has obvious application prospects and advantages in water level fluctuation monitoring in extreme weather such as earthquakes, tsunami and storm surge.

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, and 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 are helpful for modeling, prediction and early warning of water level anomalies.

[0003] In the related technology, water level measurement can be carried out through satellite altimetry, tide gauge stations or GNSS-IR (Global Navigation Satellite System Interferometric Reflectometry). Satellite altimetry is the use of an altimeter carried by an artificial 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 a 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 then obtain the water level change.

[0004] However, in the related technologies, when short-term extreme events occur, they are unable to capture the complete waveform (or peak point) 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). In addition, the sparse distribution of coastal tide gauges, high maintenance costs, and low accuracy of satellite altimetry for offshore sea level monitoring further limit their ability to measure offshore 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 single GNSS-IR solution takes a long time), 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 improvement is urgently needed. 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 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.

[0006] The first aspect of the present application provides a water level measurement method based on LEO-IR, comprising 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 according to the LEO observation data, the angle information and 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 according to 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 altitude 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-coastal 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; calculating the reflection height and the precision dilution 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 precision dilution 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] Among them, the subscripts sat1 and sat2 represent time-coherent satellite arc pairs; represents the initial reflection height; el and eldot represent the altitude angle and the rate of change of altitude angle 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 precision reduction factor 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 Respectively represent Q2×2 The element at the first row and first column and the second row and second column in the matrix; hDOP, and Respectively represent h, and the dilution of precision value of the combination of the two.

[0016] The second aspect of the present application provides a water level measurement device based on LEO-IR, including: an acquisition module, used to acquire LEO observation data and LEO broadcast ephemeris of a shore-based LEO station adjacent to a target water area; a first calculation module, used 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; a second calculation module, used to calculate 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; a third calculation module, used to calculate 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.

[0017] Optionally, in one embodiment of the present application, the second calculation module includes: a first acquisition unit, used to obtain a time-consistent satellite arc-to-altitude rate error correction model in the LEO-IR; a second acquisition unit, used to obtain a precision attenuation factor model in the LEO-IR; and a calculation unit, used to calculate the reflection height and the precision attenuation 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 attenuation factor model.

[0018] Optionally, in one embodiment of the present application, the calculation unit includes: a first calculation subunit, 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; a first generation subunit, used to use the first Fresnel reflection area to filter the angle information to obtain an available interval of the altitude angle and the azimuth angle in the angle information; an extraction unit, used to extract the available LEO observation data and the available angle information that meet the available interval from the LEO observation data and the angle information; a second generation subunit, used to segment the available LEO observation data and the available angle information based on the satellite arc time threshold and the altitude angle change rate of the LEO satellite corresponding to the shore-based LEO station to obtain the available LEO observation data and the available angle information. an initial monotonic satellite arc segment of information; a second calculating subunit, used to calculate 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-coast horizontal plane of the target water area according to the initial monotonic satellite arc segment; a third calculating subunit, used to obtain a satellite arc pair that meets a preset time condition based on the initial monotonic satellite arc segment and the intermediate moment; a third generating subunit, used to obtain the initial altitude angle and the initial altitude angle change rate of the monotonic satellite arc segment at the intermediate moment based on the intermediate moment; a fourth calculating subunit, used to calculate the reflection altitude and the precision attenuation factor based on the initial reflection altitude, the initial altitude angle, the initial altitude angle change rate, in combination with the time-consistent satellite arc pair altitude rate error correction model and the precision attenuation factor model.

[0019] 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,:

[0020] Bx=L

[0021]

[0022] Among them, the subscripts sat1 and sat2 represent time-coherent satellite arc pairs; represents the initial reflection height; el and eldot represent the altitude angle and the rate of change of altitude angle 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.

[0023] Optionally, in one embodiment of the present application, the expression of the precision reduction factor model may be, but is not limited to,:

[0024]

[0025] Among them, Q 2×2is a 2×2 square matrix; Q 11 and Q 22 Respectively represent Q 2×2 The element at the first row and first column and the second row and second column in the matrix; hDOP, and Respectively represent h, and the dilution of precision value of the combination of the two.

[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, wherein the computer-readable storage medium stores a computer program, which, when executed by a processor, 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, when executed, implements the above-mentioned LEO-IR-based water level measurement method.

[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 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 attenuation factor of the reflection height 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 temporal resolution, spatial resolution and accuracy of the water level of the target water area, and it is relatively simple to implement. Thus, the problem in the related art that the requirements for monitoring water level fluctuations caused by short-term extreme events cannot be fully met due to the low temporal resolution, spatial resolution or accuracy of satellite altimetry, tide gauge stations, GNSS-IR, etc. when short-term extreme events occur is solved.

[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 the 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 A flow chart of a water level measurement method based on LEO-IR provided according to an embodiment of the present application;

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

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

[0035] Figure 4 A flowchart of the working principle of a water level measurement method based on LEO-IR according to an embodiment of the present application;

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

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

[0038] Embodiments of the present application are described in detail below, and examples of the embodiments 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 the water level measurement method and device based on LEO-IR of the embodiment of the present application with reference to the accompanying drawings. In view of the problem mentioned in the above background technology that the time resolution or spatial resolution or accuracy of satellite altimetry, tide gauge station, 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 according to the LEO broadcast ephemeris obtained by the shore-based LEO station adjacent to the target water area and the actual position of the shore-based LEO station, and then the reflection height between the phase center of the shore-based LEO station antenna and the near-coast horizontal plane of the target water area and the precision attenuation factor of the reflection height are calculated according to the LEO observation data and angle information obtained by the shore-based LEO station and LEO-IR, and then the water level height of the target water area is calculated, which improves the time resolution, spatial resolution and accuracy of the water level height of the target water area, and is 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 can be understood that, from the perspective of data source, the embodiment of the present application uses the shore-based LEO station near the target water area to obtain the LEO observation data and LEO broadcast ephemeris of the target water area. Compared with the GNSS medium and high orbit navigation satellites, LEO satellites move faster relative to the earth (about 30 times), and a complete LEO constellation usually has more 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] Among them, in the embodiment of the present application, the LEO observation data may include but is not limited to signal-to-noise ratio and signal strength indicators, etc., and the present application does not make specific limitations.

[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 waters, which can be specifically set by technicians in this field according to actual conditions, and this application does not impose any specific limitations.

[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 embodiments 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 limitations.

[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 shore-based LEO station stored locally.

[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 according to 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 geocentric earth-fixed system coordinates of the LEO satellite and the position coordinates of the actual position of the shore-based LEO station stored locally.

[0054] Among them, 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 according to the station center coordinate system coordinates of the LEO satellite.

[0056] Among them, the angle information of 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 make specific restrictions. The calculation formula may be but is not limited to:

[0057]

[0058] where (e(t), n(t), u(t)) represents the station-centered coordinate system coordinates of the LEO satellite 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) represent the azimuth, altitude and altitude change rate of the LEO satellite relative to the shore-based LEO station at epoch t respectively; 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-coastal horizontal plane of the target waters and the precision dilution 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 its 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 precision dilution 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 LEO observation data and angle information and LEO-IR, including: obtaining a time-consistent satellite arc-to-height rate error correction model in LEO-IR; obtaining a precision dilution factor model in LEO-IR; and calculating the reflection height and the precision dilution factor based on the LEO observation data and angle information, combining the time-consistent satellite arc-to-height rate error correction model and the precision dilution factor model. The expression of the time-consistent satellite arc-to-height rate error correction model can be, but is not limited to,:

[0062] Bx=L

[0063]

[0064] Among them, the subscripts sat1 and sat2 represent time-coherent satellite arc pairs; represents the initial reflection height; el and eldot represent the altitude angle and the rate of change of altitude angle 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 precision reduction factor 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 Respectively represent Q 2×2 The element at the first row and first column and the second row and second column in the matrix; hDOP, and Respectively represent h, and the dilution of precision value of the combination of the two.

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

[0069] Bx=L

[0070]

[0071] Among them, the subscripts sat1 and sat2 represent time-coherent satellite arc pairs; represents the initial reflection height; el and eldot represent the altitude angle and the rate of change of altitude angle respectively; h and Respectively represent the reflection height and its rate of change; 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. The model uses the relationship that "the reflection height change rate of the time-consistent satellite arc pair is consistent" to cleverly correct the highly random height rate error; this model has no smoothness assumption and is suitable for monitoring nearshore water level fluctuations in extreme ocean event scenarios.

[0072] In some embodiments, the present application can quantitatively describe the accuracy of LEO-IR height measurement results by establishing a precision reduction factor to evaluate the correction effect of the height rate error. The expression of the precision reduction factor 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 Respectively represent Q 2×2 The element at the first row and first column and the second row and 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 height rate error correction process, 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 attenuation factor are calculated 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 attenuation 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 the azimuth angle in the angle information; extracting the available LEO observation data and the available angle information that meet the available range in the LEO observation data and the angle information; and calculating the satellite arc time threshold of the shore-based LEO station corresponding to the LEO satellite. The available LEO observation data and the available angle information are divided according to the value and the rate of change of the altitude angle to obtain the initial monotonic satellite arc segment of the available LEO observation data and the 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 the precision dilution factor are calculated based on the initial reflection height, the initial altitude angle and the rate of change of the initial altitude angle, 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 near-coastal horizontal plane of the target water area based on the 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 range of the elevation angle and the azimuth angle.

[0078] Among them, the a priori rough reflection height of the embodiment of the present application can be determined based on a priori knowledge. When the reflecting surface is a near-coastal horizontal plane, the priori 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 may 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-axis of the ellipse, respectively; h rrepresents the a priori rough reflection height; λ represents the carrier wavelength; el represents the altitude 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 LEO observation data and angle information according to available intervals of altitude angle and azimuth angle.

[0084] Step S303: Segment the available LEO observation data and available angle information into initial monotonic satellite arcs according to the satellite arc 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 make any specific limitations.

[0086] Exemplarily, the embodiment of the present application can first segment according to the satellite arc time threshold, and then segment 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 when this threshold is exceeded; the altitude angle change rate is divided into two cases, increasing and decreasing, and segmentation is performed when the situation of the previous and subsequent 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 of the satellite arc segment and the end time of the satellite arc segment, which can be specifically set by technicians in this field according to actual conditions, and this application does not make 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; Represents 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 the embodiment of the present application, according to the time threshold of the satellite arc pair with consistent time and the middle moment of the satellite arc segment, the satellite arc pair with consistent time can be matched, and then the monotonic satellite arc pair that meets certain time conditions can be obtained. In the embodiment of the present application, the certain time condition can be set by those skilled in the art according to the actual situation, and the present application does not make any specific limitation.

[0094] Furthermore, in an embodiment of the present application, when the absolute value of the difference between the intermediate moments of two satellite arc segments is smaller than the time threshold of a time-consistent satellite arc pair, the two satellite arc segments are successfully matched into a time-consistent satellite arc pair; the time threshold of a 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 initial altitude angle change rate, combined with LEO-IR, the reflection height and the precision reduction factor are calculated.

[0096] Among them, the embodiment of the present application can calculate the reflection height based on the time-consistent satellite arc to 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 factor and the height of the antenna phase center.

[0098] In the actual implementation process, the embodiment of the present application can calculate the water level height of the near-shore 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 in conjunction with a specific embodiment.

[0101] in, Figure 4 The present invention is a flow chart of the working principle of a water level measurement method based on LEO-IR provided 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 precision reduction 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 based on LEO-IR.

[0105] Step S404: The ground computing center calculates the water level of the near-coastal horizontal plane according to the reflection height, the attenuation 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 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 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 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 or 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 is solved.

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

[0108] Figure 5 It is a block diagram of a water level measurement device based on LEO-IR provided 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 used 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 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 reduction factor of the reflection height according to the LEO observation data and angle information and LEO-IR.

[0113] The third calculation module 400 is used to calculate the water level height of the near-shore horizontal surface based on the reflection height, the dilution of precision factor 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 the time-consistent satellite arc-to-altitude rate error correction model in LEO-IR.

[0116] The second acquisition unit is used to acquire the precision reduction factor model in LEO-IR.

[0117] The first calculation unit is used to calculate the reflection height and the precision dilution factor according to the LEO observation data and angle information, combined 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 used to filter the angle information by using the first Fresnel reflection zone to obtain the available range 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 used to segment the available LEO observation data and the available angle information based on the satellite arc time threshold and the altitude angle change rate of the LEO satellite corresponding to the shore-based LEO station to obtain the initial monotonic satellite arc segment of the available LEO observation data and the available angle information.

[0123] The second calculation subunit is used to calculate 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-coast horizontal plane of the target water area according to the initial monotonic satellite arc.

[0124] The third calculation subunit is used to obtain a satellite arc pair that meets a preset time condition based on the initial monotonic satellite arc segment and the intermediate time.

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

[0126] The fourth calculation subunit is used to calculate the reflection height and the precision reduction factor based on the initial launch height, the initial altitude angle, the initial altitude angle change rate, and LEO-IR.

[0127] 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:

[0128] Bx=L

[0129]

[0130] Among them, the subscripts sat1 and sat2 represent time-coherent satellite arc pairs; represents the initial reflection height; el and eldot represent the altitude angle and the rate of change of altitude angle 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.

[0131] Optionally, in one embodiment of the present application, the expression of the precision reduction factor model may be, but is not limited to,:

[0132]

[0133] Among them, Q 2×2 is a 2×2 square matrix; Q 11 and Q 22 Respectively represent Q 2×2 The element at the first row and first column and the second row and second column in the matrix; hDOP, and Respectively represent h, and the dilution of precision value of the combination of the two.

[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 of 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 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 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 LEO-IR, and then the water level of the target water area is calculated, thereby improving the temporal resolution, spatial resolution and accuracy of the water level of the target water area, and it is relatively simple to implement. Thus, the problem in the related art that the requirements for monitoring water level fluctuations caused by short-term extreme events cannot be fully met when short-term extreme events occur due to the low temporal resolution, spatial resolution or accuracy of satellite altimetry, tide gauge stations, GNSS-IR, etc. 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 water level measurement method based on LEO-IR provided in the above embodiment is implemented.

[0139] Furthermore, the electronic device further comprises:

[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 executed 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, the processor 602 and the communication interface 603 are implemented independently, the communication interface 603, the memory 601 and the processor 602 can be connected to each other through 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 only 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), or 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 also 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 also 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" etc. 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 may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0149] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and 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 the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0151] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk 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 may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

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

[0153] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0154] In addition, each functional unit in each embodiment 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 one 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 can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify 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 of shore-based low earth orbit 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-coastal horizontal plane of the target waters and the precision dilution factor of the reflection height according to the LEO observation data, the angle information and the LEO-interferometric reflection measurement IR; The water level height of the target water area is calculated based on the reflection height, the dilution of precision factor, and the height of the antenna phase center.

2. The method according to claim 1, characterized in that: The calculating, based on the LEO observation data, the angle information and the LEO-IR, 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 dilution factor of the reflection height comprises: 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; The reflection height and the dilution of precision factor are calculated 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.

3. The method according to claim 2, characterized in that The calculating the reflection height and the dilution of precision factor according to the LEO observation data and the angle information in combination with the time-consistent satellite arc-to-height rate error correction model and the dilution of precision factor model comprises: Calculating the first Fresnel reflection zone of the shore-based LEO station based on the a priori rough reflection height of the shore-based LEO station; Using the first Fresnel reflection zone to filter the angle information, so as to obtain available 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; Based on a satellite arc time threshold and an altitude angle change rate of the shore-based LEO station corresponding to the LEO satellite, segmenting the available LEO observation data and the available angle information to obtain an initial monotonic satellite arc of the available LEO observation data and the available angle information; Calculate the middle 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 according to the initial monotonic satellite arc segment; Obtaining a satellite arc pair satisfying a preset time condition based on the initial monotonic satellite arc segment and the intermediate time; Based on the intermediate moment, the initial elevation angle and the rate of change of the initial elevation angle of the monotonic satellite arc segment at the intermediate moment are obtained; Based on the initial reflection altitude, the initial altitude angle, and the rate of change of the initial altitude angle, the reflection altitude and the dilution of precision factor are calculated in combination with the time-consistent satellite arc to altitude rate error correction model and the dilution of precision factor model.

4. The method according to claim 2, characterized in that: The expression of the time-consistent satellite arc to height rate error correction model is: Bx=L Among them, the subscripts sat1 and sat2 represent time-coherent satellite arc pairs; represents the initial reflection height; el and eldot represent the altitude angle and the rate of change of altitude angle 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.

5. The method according to claim 2, characterized in that: The expression of the precision reduction factor model is: Among them, Q 2×2 is a 2×2 square matrix; Q 11 and Q 22 Respectively represent Q 2×2 The element at the first row and first column and the second row and second column in the matrix; hDOP, and Respectively represent h, and the dilution of precision value of the combination of the two.

6. 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 station adjacent to the target waters; A first calculation module is used 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; 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-coastal horizontal plane of the target waters and the precision reduction factor of the reflection height according to the LEO observation data, the angle information and the LEO-IR; The third calculation module is used to calculate 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.

7. The device according to claim 6, characterized in that The second calculation module includes: A first acquisition unit is used to acquire a time-consistent satellite arc-to-altitude rate error correction model in the LEO-IR; A second acquisition unit is used to acquire a dilution of precision model in the LEO-IR; The first calculation unit is used to calculate the reflection height and the precision dilution factor according to the LEO observation data and the angle information in combination with the time-consistent satellite arc-to-height rate error correction model and the precision dilution factor model.

8. 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 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the water level measurement method based on LEO-IR as described in any one of claims 1 to 6.

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

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