Low-orbit multi-beam power positioning and timing method and device

Abstract

The present application relates to a low-orbit multi-beam power positioning and timing method and device. The method includes: calculating the beam power value received by the user based on the satellite signal, free space transmission loss and the user receiving antenna gain; deducing the satellite angle based on the collective relationship between the user and the satellite, and when the user receives multiple beam signals, considering the power observation noise, using the satellite angle and the beam power value received by the user to establish a multi-beam power observation equation group; linearizing the multi-beam power observation equation group and solving the roots of the linearized multi-beam power observation equation group to obtain the pitch angle and azimuth angle between the satellite and the user; using the link loss and the pitch angle and azimuth angle between the satellite and the user to deduce the distance between the user and the satellite and the user's elevation level information to obtain the positioning and timing results. This method can be used to obtain the user's approximate position and local time in a low-orbit satellite scenario.

Description

Technical Field

[0001] The present application relates to the field of satellite navigation technology, and in particular to a low-orbit multi-beam power positioning and timing method and device. Background Art

[0002] Compared to the medium- and high-orbit satellites commonly used in traditional satellite navigation constellations, low-orbit satellites offer reduced spatial signal attenuation, faster satellite mobility, and deeper integration of communication and navigation. These advantages effectively offset the shortcomings of medium- and high-orbit satellites, such as low signal landing power and low message rates. In the early stages of low-orbit navigation constellation construction, the number of low-orbit satellites was insufficient, traditional pseudorange and carrier phase positioning and timing solutions were not readily available, and Doppler positioning systems generally took a long time to converge.

[0003] However, current research on power-based localization primarily focuses on indoor matching. Because multiple WiFi access points (APs) can be detected indoors and their signals are easily measured, fingerprint localization methods based on WiFi received signal strength indication (RSSI) have become one of the most popular localization technologies. This method typically consists of two phases: offline and online. The offline phase collects the received signal strength of reference points in the localization area as a fingerprint database; the online phase acquires real-time localization data and matches it with the fingerprint database to obtain an estimated position. There are two main approaches to solving power-based localization. Traditional methods use various exponents to calculate the similarity between the fingerprint vector and the observation vector, such as Euclidean distance, cosine similarity, Pearson coefficient, and other methods. Most of these methods employ direct difference calculations. However, they struggle to accurately describe the complex nonlinear relationships between signal vectors. Classification and clustering methods employ machine learning (ML) and deep learning (DL) for neighbor matching. These methods can be broadly divided into two groups: supervised learning methods utilize various classification methods, such as random forests (RF), decision trees (DT), Bayesian classification, support vector machines (SVMs), neural networks (NNs), convolutional neural networks (CNNs), and other classification algorithms. Unsupervised learning methods utilize clustering, K-means, fuzzy clustering, and density-based spatial clustering with noise. Classification and clustering methods are expected to be able to quickly determine the user's approximate location using a test set after the database is generated. However, they are not applicable to low-Earth orbit satellite scenarios. Summary of the Invention

[0004] Based on this, it is necessary to provide a low-orbit multi-beam power positioning and timing method and device that can obtain the user's approximate position and local time in a low-orbit satellite scenario to address the above technical problems.

[0005] A low-orbit multi-beam power positioning and timing method, the method comprising:

[0006] Acquire satellite signals; calculate the beam power value received by the user based on the satellite signals, free space transmission loss, and the user receiving antenna gain;

[0007] The satellite angle is derived from the collective relationship between users and satellites. When a user receives multiple beam signals, the multi-beam power observation equations are established using the satellite angle and the beam power values ​​received by the user, taking into account the power observation noise.

[0008] The multi-beam power observation equations are linearized and expanded, and the roots of the linearized multi-beam power observation equations are solved to obtain the elevation angle and azimuth angle between the satellite and the user.

[0009] The link loss and the elevation and azimuth angles between the satellite and the user are used to deduce the distance between the user and the satellite and the user's elevation level information to obtain the positioning and timing results.

[0010] The above-mentioned low-orbit multi-beam power positioning and timing method and device, the present application obtains the EIRP value of the satellite transmission signal and the user receiving antenna gain value through antenna simulation or actual measurement, obtains the theoretical receiving power of users at different positions through link budget and uses it as a power fingerprint library; then, establishes an equation group for the user's actual received multi-beam power observation quantity, linearizes the multi-beam power observation equation group and solves the roots of the multi-beam power observation equation group after linear expansion to obtain the pitch angle and azimuth angle between the satellite and the user; finally, the link loss and the geometric relationship between the satellite and the user can be used to deduce the distance between the user and the satellite and the user's elevation level information, and then obtain the positioning and timing results. The simulation results show that the present application can obtain a positioning effect of the order of kilometers, and the availability of high-elevation-angle users is strong, and the positioning and timing results can be obtained in a shorter time, with high positioning efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic diagram of a flow chart of a low-orbit multi-beam power positioning and timing method in one embodiment;

[0012] Figure 2 A schematic diagram of a process for solving the roots of the linearized expanded multi-beam power observation equations in one embodiment;

[0013] Figure 3 1. A diagram showing the influence of different user elevation azimuth angles on satellite elevation deviation in one embodiment;

[0014] Figure 4 2. This is a diagram showing the influence of different user pitch azimuth angles on user horizontal deviation in another embodiment;

[0015] Figure 5A schematic diagram of the horizontal and vertical error deviation of users at different elevation angles in one embodiment;

[0016] Figure 6 The present invention relates to a low-orbit multi-beam signal power positioning and timing device in one embodiment. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0018] In one embodiment, Figure 1 As shown, a low-orbit multi-beam power positioning and timing method is provided, comprising the following steps:

[0019] Step 102: Acquire satellite signals; calculate the beam power value received by the user based on the satellite signals, free space transmission loss, and the user receiving antenna gain.

[0020] In low-orbit satellite navigation systems, the transmitting antenna is typically a planar phased array antenna with the characteristic of multi-beam polling broadcast. Users in different locations receive different power levels of signals from different beams. This characteristic allows for positioning and timing using power observation. By considering the gain of the user's receiving antenna and combining it with transmission loss, the final beam power value can be derived, ensuring an accurate assessment of signal strength and laying the foundation for subsequent analysis.

[0021] This application calculates the beam power value received by the user based on the satellite signal, free space transmission loss and the user receiving antenna gain, which facilitates the subsequent establishment of an equation group for the user's actual received multi-beam power observation quantity.

[0022] Step 104: The satellite angle is derived based on the collective relationship between the user and the satellite. When the user receives multiple beam signals, a multi-beam power observation equation group is established using the satellite angle and the beam power value received by the user, taking into account the power observation noise.

[0023] By analyzing the relative position of the user and multiple satellites, the satellite's angle of field (i.e., the angle of the satellite relative to the user) can be derived, enabling understanding of the signal source and direction. The theoretical received power of users at different locations is used as a power fingerprint database. A set of equations is established for the user's actual multi-beam received power observations, describing the relationship between different signal sources and the user.

[0024] Step 106 , linearize and expand the multi-beam power observation equations and solve the roots of the linearized expanded multi-beam power observation equations to obtain the elevation angle and azimuth angle between the satellite and the user.

[0025] Step 108: Use the link loss and the elevation and azimuth angles between the satellite and the user to deduce the distance between the user and the satellite and the user's elevation level information to obtain the positioning and timing results.

[0026] By linearizing and solving the multi-beam power observation equations, we can quickly obtain the distance and orientation between the satellite and the user, significantly reducing calculation time. This not only accurately determines the user's location but also rapidly responds to dynamic changes in the low-orbit satellite environment. This approach, which integrates multiple signal processing techniques, provides powerful support for positioning and timing of low-orbit satellites, overcoming the shortcomings of traditional positioning technologies in terms of signal quality and real-time performance.

[0027] In the above-mentioned low-orbit multi-beam power positioning and timing method, the present application obtains the EIRP value of the satellite transmission signal and the user receiving antenna gain value through antenna simulation or actual measurement, obtains the theoretical receiving power of users at different positions through link budgeting and uses it as a power fingerprint library; then, an equation group is established for the user's actual received multi-beam power observation quantity, the multi-beam power observation equation group is linearly expanded and the roots of the multi-beam power observation equation group after linear expansion are solved to obtain the pitch angle and azimuth angle between the satellite and the user; finally, the link loss and the geometric relationship between the satellite and the user can be used to deduce the distance between the user and the satellite and the user's elevation level information, and then obtain the positioning and timing results. The simulation results show that the present application can obtain a positioning effect of the order of kilometers, and the availability of high-elevation-angle users is strong, and the positioning and timing results can be obtained in a shorter time, with high positioning efficiency.

[0028] In one embodiment, calculating the beam power value received by the user based on the satellite signal, free space transmission loss, and the user receiving antenna gain includes:

[0029] The beam power value received by the user is calculated based on the satellite signal, free space transmission loss and user receiving antenna gain.

[0030] [dB]

[0031] in, Pitch angle , azimuth is , the altitude is Users receive satellite signals, .

[0032] In one embodiment, the satellite angle is derived based on the set relationship between the user and the satellite, including:

[0033] According to the set relationship between users and satellites, the satellite angle is obtained as

[0034]

[0035] in, represents the radius of the Earth, Indicates the user's altitude. represents the pitch angle, Indicates the satellite orbit altitude.

[0036] In one embodiment, when a user receives multiple beam signals, a multi-beam power observation equation set is established using the satellite angle and the beam power value received by the user, taking into account power observation noise, including:

[0037] When the user receives multiple beam signals, the multi-beam power observation equations are established by taking into account the power observation noise and using the satellite angle and the beam power value received by the user:

[0038]

[0039] in, Indicates the EIRP difference between beam M and beam 1, represents the Mth beam, represents the power observation noise in the M-beam signal link, Indicates the difference in received power of beam M compared to beam 1. .

[0040] In one embodiment, linearizing and expanding the multi-beam power observation equations and solving the roots of the linearized expanded multi-beam power observation equations to obtain the elevation angle and azimuth angle between the satellite and the user includes:

[0041] Assumptions and The initial values ​​are and , the multi-beam power observation equations are linearly expanded, and then:

[0042]

[0043] make:

[0044] ,

[0045]

[0046]

[0047] Then the above equations can be rewritten as:

[0048] We can further solve it to get:

[0049]

[0050] The user's elevation information is negligible relative to the satellite orbit height and the earth's radius. When is first considered as zero;

[0051] in, Indicates the EIRP difference between beam M and beam 1, represents the power observation noise in the M-beam signal link, Indicates the difference in received power between beam M and beam 1.

[0052] In a specific embodiment, Figure 2 The figure shows the process of solving the linearized expanded multi-beam power observation equations, solving for user position and time. The error bias and standard deviation can be obtained by statistically analyzing the results of multiple Monte Carlo simulations. In this embodiment, the number of solutions is 10, and the number of Monte Carlo simulations for a single user is 1000.

[0053] In one embodiment, the distance between the user and the satellite and the user's elevation level information are derived using the link loss and the elevation and azimuth angles between the satellite and the user to obtain positioning and timing results, including:

[0054] The distance between the user and the satellite is derived using the link loss:

[0055]

[0056] in, Link loss;

[0057] The user time difference information is obtained as follows: ;

[0058] in, Represents the speed of light.

[0059] In one embodiment, the distance between the user and the satellite and the elevation and horizontal information of the user are derived by using the distance between the user and the satellite and the elevation and azimuth angles between the satellite and the user.

[0060]

[0061]

[0062] in, represents the radius of the Earth, represents the satellite orbit altitude, represents the pitch angle, .

[0063] Figure 3 Given a traversal pitch angle of 10 ~90 , azimuth 0 ~360 The power positioning solution of all users is shown in the figure, taking the satellite elevation angle error deviation as an example. Since the initial value uncertainty is 2 , then the maximum deviation of the solution divergence does not exceed ±1 , when the user deviation is greater than the threshold, the power positioning method result should be restored to the initial value. It can be seen that when the user pitch angle is less than 40 When the power positioning pitch angle error is large, when the user pitch angle is greater than When the power positioning pitch angle error is generally small. According to statistics, the pitch angle deviation of all users is 1.1 , with a standard deviation of 0.5 degrees.

[0064] Figure 4 The error of calculating the user's horizontal and elevation information using the pitch angle and azimuth angle is given. Taking the user's horizontal error deviation as an example, since the calculation formula is tightly coupled with the pitch angle, the obtained error deviation changes similarly to the pitch angle deviation. It can be seen that when the user's pitch angle is less than 40 When the user's pitch angle is greater than 40 When the horizontal error is generally small, the horizontal error deviation is generally small. According to statistics, the horizontal error deviation of all users is -1417.7m, with a standard deviation of 53403m.

[0065] Figure 5 The horizontal and elevation error deviations of users at different elevation angles are given. The average elevation deviation of all users is 7093.5m, the average horizontal deviation is 7009.3m, and the average timing error is 123. When the user's elevation angle is less than 30 At 10:00 a.m., the elevation deviation and horizontal deviation were large, 15546m and 17180m respectively, and the timing error was 305.8 , which is higher than the overall mean level; and when the user's elevation angle is higher than 30 At 10:00 a.m., the average values ​​of elevation deviation and horizontal deviation were 4231.2m and 3567.1m respectively, and the timing error was 62.3 , which is generally lower than the overall mean level. This indicates that users at high elevation angles are more likely to obtain good power positioning and timing performance.

[0066] It should be understood that although Figure 1The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. In addition, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0067] In one embodiment, Figure 6 As shown, a low-orbit multi-beam signal power positioning and timing device is provided, including: a beam power value calculation module 602, a multi-beam power observation equation group establishment module 604, an equation group solving module 606 and a positioning and timing module 608, wherein:

[0068] The beam power value calculation module 602 is used to obtain satellite signals; calculate the beam power value received by the user based on the satellite signals, free space transmission loss and user receiving antenna gain;

[0069] A module 604 for establishing a multi-beam power observation equation set is used to derive the satellite angle based on the set relationship between the user and the satellite. When the user receives multiple beam signals, the multi-beam power observation equation set is established using the satellite angle and the beam power value received by the user, taking into account power observation noise.

[0070] The equation solving module 606 is used to linearize the multi-beam power observation equations and solve the roots of the linearized multi-beam power observation equations to obtain the elevation angle and azimuth angle between the satellite and the user;

[0071] The positioning and timing module 608 is used to deduce the distance between the user and the satellite and the user's elevation information by using the link loss and the pitch angle and azimuth angle between the satellite and the user to obtain the positioning and timing results.

[0072] For the specific definition of a low-orbit multi-beam signal power positioning and timing device, please refer to the definition of a low-orbit multi-beam power positioning and timing method above, which will not be repeated here. The various modules in the above-mentioned low-orbit multi-beam signal power positioning and timing device can be implemented in whole or in part through software, hardware and their combination. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0073] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A low-orbit multi-beam power positioning and timing method, characterized in that: The method comprises: Obtaining a satellite signal; calculating a beam power value received by a user based on the satellite signal, free space transmission loss, and user receiving antenna gain; The satellite angle is derived based on the collective relationship between the user and the satellite. When the user receives multiple beam signals, a multi-beam power observation equation group is established using the satellite angle and the beam power value received by the user, taking into account power observation noise. Linearizing and expanding the multi-beam power observation equations and solving the roots of the linearized expanded multi-beam power observation equations to obtain the elevation angle and azimuth angle between the satellite and the user; The distance between the user and the satellite and the user's elevation level information are derived using the link loss and the elevation and azimuth angles between the satellite and the user to obtain the positioning and timing results. When a user receives multiple beam signals, a multi-beam power observation equation group is established using the satellite angle and the beam power value received by the user, taking into account the power observation noise, including: When the user receives multiple beam signals, the multi-beam power observation equations are established by taking into account the power observation noise and using the satellite angle and the beam power value received by the user: Where ΔE M (γ, β) represents the EIRP difference between beam M and beam 1, M represents beam M, represents the power observation noise in the M-beam signal link, Indicates the difference in received power of beam M compared to beam 1. γ represents the satellite angle, and β represents the azimuth; The link loss and the elevation and azimuth angles between the satellite and the user are used to derive the distance between the user and the satellite and the user's elevation level information, and obtain positioning and timing results, including: The distance between the user and the satellite is derived using the link loss: d＝10 0.05L(α,h)+0.5log10(4π) Where L(α,h) represents the free space transmission loss, i.e., the link loss; The user time difference information is obtained as follows: Where c represents the speed of light; The distance between the user and the satellite and the pitch angle and azimuth between the satellite and the user are used to deduce the distance between the user and the satellite and the user's elevation information and horizontal information respectively. Where R is the radius of the Earth, H is the altitude of the satellite orbit, α is the pitch angle, β is the azimuth angle, and γ is the satellite angle.

2. The method according to claim 1, characterized in that Calculating a user received beam power value according to the satellite signal, free space transmission loss, and user receiving antenna gain, including: The beam power value received by the user is calculated based on the satellite signal, free space transmission loss and user receiving antenna gain. P k (a,b,h)=E k (a,b)+L(a,h)+G(a) Among them, E k (α, β) represents the satellite signal received by a user with an elevation angle of α, an azimuth angle of β, and an altitude of h. L(α, h) represents the free space transmission loss. G(α) represents the user receiving antenna gain, and k represents the beam number.

3. The method according to claim 1, characterized in that The satellite angle is derived based on the set relationship between users and satellites, including: According to the set relationship between users and satellites, the satellite angle is obtained as Where R is the radius of the earth, h is the user's altitude, α is the user's pitch angle, and H is the satellite orbit height.

4. The method according to claim 1, wherein The multi-beam power observation equation group is linearized and solved to obtain the root of the linearized multi-beam power observation equation group to obtain the elevation angle and azimuth angle between the satellite and the user, including: Assuming that the initial values ​​of γ and β are γ0 and β0 respectively, the multi-beam power observation equations are linearly expanded, and then: make: Then the above equations can be rewritten as: X[γ-γ0β-β0] T =y+n We can further solve it to get: [c b] T =[γ0β0] T +X -1 (y+n) The user's elevation information is negligible relative to the satellite orbit height and the earth's radius. When is first considered as zero; Among them, γ represents the satellite angle, β represents the azimuth, and ΔE M (γ, β) represents the EIRP difference between beam M and beam 1, M represents beam M, represents the power observation noise in the M-beam signal link, Indicates the difference in received power between beam M and beam 1.

5. A low-orbit multi-beam power positioning and timing device, characterized in that: The device comprises: A beam power value calculation module is used to obtain satellite signals; calculate the beam power value received by the user based on the satellite signals, free space transmission loss and user receiving antenna gain; A multi-beam power observation equation group module is established to derive the satellite angle based on the set relationship between the user and the satellite. When the user receives multiple beam signals, the multi-beam power observation equation group is established using the satellite angle and the beam power value received by the user, taking into account the power observation noise, including: When the user receives multiple beam signals, the multi-beam power observation equations are established by taking into account the power observation noise and using the satellite angle and the beam power value received by the user: Where ΔE M (γ, β) represents the EIRP difference between beam M and beam 1, M represents beam M, represents the power observation noise in the M-beam signal link, It represents the difference in received power of beam M compared with beam 1, γ represents the satellite angle, and β represents the azimuth; an equation solving module, configured to linearize and expand the multi-beam power observation equations and solve the roots of the linearized expanded multi-beam power observation equations to obtain the elevation angle and azimuth angle between the satellite and the user; The positioning and timing module is used to derive the distance between the user and the satellite and the user's elevation information by using the link loss and the pitch and azimuth angles between the satellite and the user to obtain the positioning and timing results; The link loss and the elevation and azimuth angles between the satellite and the user are used to derive the distance between the user and the satellite and the user's elevation level information, and obtain positioning and timing results, including: The distance between the user and the satellite is derived using the link loss: Where L(α,h) represents the free space transmission loss, i.e., the link loss; The user time difference information is obtained as follows: Where c represents the speed of light; The distance between the user and the satellite and the pitch angle and azimuth between the satellite and the user are used to deduce the distance between the user and the satellite and the user's elevation information and horizontal information respectively. Where R is the radius of the Earth, H is the altitude of the satellite orbit, α is the pitch angle, β is the azimuth angle, and γ is the satellite angle.

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