Method, device and equipment for capturing and tracking low-orbit satellite and medium-orbit satellite and medium, and medium

Abstract

The application relates to the technical field of satellite navigation, and discloses a low-orbit satellite and medium-orbit satellite acquisition tracking method, which comprises the following steps: acquiring the orbital height of a satellite and the Doppler rate of a satellite signal; determining the type of the satellite based on the orbital height and the Doppler rate; determining the acquisition parameters and the tracking loop parameters corresponding to the satellite based on the type of the satellite; acquiring the satellite according to the acquisition parameters, wherein the acquisition parameters comprise a Doppler search step and a coherent integration time; and setting a tracking loop according to the tracking loop parameters to track the satellite, wherein the tracking loop parameters comprise Kalman filter weights, a phase-locked loop bandwidth and a frequency-locked loop bandwidth. The application adjusts the acquisition parameters of a receiver according to the type of the satellite to quickly acquire a low-orbit satellite signal and reduce the acquisition time of a medium-orbit satellite signal, and adjusts the tracking loop parameters of the receiver according to the type of the satellite to ensure the tracking accuracy of the medium-orbit satellite signal and improve the tracking stability of the low-orbit satellite signal.

Description

Technical Field

[0001] This application relates to the field of satellite navigation technology, specifically to a method, apparatus, equipment, and medium for capturing and tracking low-Earth orbit and medium-Earth orbit satellites. Background Technology

[0002] Low Earth orbit (LEO) satellites are artificial satellites that operate at an altitude of approximately 500-2000 kilometers above the Earth's surface. Medium Earth orbit (MEO) satellites are artificial satellites that operate at an altitude of approximately 2000-30000 kilometers above the Earth's surface. With the rapid development of LEO satellite constellations, future navigation systems will present a hybrid constellation pattern where LEO and MEO satellites (such as GPS, BeiDou, and Galileo) coexist.

[0003] The difference in orbital altitude between low-Earth orbit (LEO) and medium-Earth orbit (MEO) satellites results in significant differences in their signal reception characteristics. The acquisition and tracking loop parameters of traditional satellite navigation receivers cannot efficiently acquire and track both LEO and MEO satellites simultaneously in a mixed constellation environment. Summary of the Invention

[0004] The purpose of this application is to provide a method, apparatus, device, and medium for capturing and tracking low-Earth orbit (LEO) and medium-Earth orbit (MEO) satellites, in order to solve the problem that the acquisition parameters and tracking loop parameters of traditional satellite navigation receivers in the prior art cannot efficiently capture and track LEO and MEO satellites simultaneously in a mixed constellation environment.

[0005] To achieve the above objectives, the first aspect of this application provides a method for acquiring and tracking low-Earth orbit (LEO) satellites and medium-Earth orbit (MEO) satellites, the method comprising:

[0006] The satellite's orbital altitude and the Doppler rate of change of the satellite signal are obtained, where the satellite signal is transmitted by the satellite;

[0007] Based on orbital altitude and Doppler variation rate, the satellite type is determined, including low-Earth orbit (LEO) satellites and medium-Earth orbit (MEO) satellites.

[0008] Based on the type of satellite, determine the corresponding acquisition parameters and tracking loop parameters;

[0009] The satellite is captured according to the capture parameters, which include the Doppler search step size and the coherent integration time. The Doppler search step size corresponding to the low-Earth orbit satellite is greater than that corresponding to the medium-Earth orbit satellite, and the coherent integration time corresponding to the low-Earth orbit satellite is less than that corresponding to the medium-Earth orbit satellite.

[0010] The tracking loop is set according to the tracking loop parameters to track the satellite. The tracking loop parameters include Kalman filter weights, phase-locked loop bandwidth, and frequency-locked loop bandwidth. The Kalman filter weights corresponding to low-Earth orbit (LEO) satellites are greater than those corresponding to medium-Earth orbit (MEO) satellites. The phase-locked loop bandwidths corresponding to LEO satellites are greater than those corresponding to MEO satellites. The frequency-locked loop bandwidths corresponding to LEO satellites are greater than those corresponding to MEO satellites.

[0011] In this application embodiment, the satellite type is determined based on orbital altitude and Doppler variation rate, including:

[0012] If the orbital altitude is less than or equal to the first preset threshold and the Doppler rate of change is greater than or equal to the second preset threshold, the satellite type is determined to be a low-Earth orbit satellite.

[0013] If the orbital altitude is greater than the first preset threshold and less than or equal to the third preset threshold, and the Doppler change rate is less than the fourth preset threshold, the satellite type is determined to be a medium-Earth orbit satellite, wherein the fourth preset threshold is less than the second preset threshold.

[0014] In this embodiment of the application, the method further includes:

[0015] Based on the captured parameters, a local pseudocode and carrier signal are generated;

[0016] Based on local pseudocode, carrier signal, and satellite signal, determine the peak value of the acquisition signal generated when acquiring the satellite;

[0017] If the peak value of the acquired signal exceeds a preset threshold, the satellite acquisition is considered successful.

[0018] In this embodiment, the acquisition parameters further include Doppler search range, incoherent accumulation count, and code phase search step size. The tracking loop parameters include data bit synchronization tolerance. Specifically, the absolute value of the Doppler search range corresponding to the low-Earth orbit satellite is greater than the absolute value of the Doppler search range corresponding to the medium-Earth orbit satellite; the incoherent accumulation count corresponding to the low-Earth orbit satellite is greater than the incoherent accumulation count corresponding to the medium-Earth orbit satellite; the code phase search step size corresponding to the low-Earth orbit satellite is greater than the code phase search step size corresponding to the medium-Earth orbit satellite; and the absolute value of the data bit synchronization tolerance corresponding to the low-Earth orbit satellite is greater than the absolute value of the data bit synchronization tolerance corresponding to the medium-Earth orbit satellite.

[0019] In this embodiment of the application, the method further includes:

[0020] Based on orbital altitude and Doppler variation rate, determine whether the satellite type has changed;

[0021] When the satellite type changes, the phase-locked loop bandwidth is linearly interpolated within a preset transition time window, and the Kalman filter weights are adjusted.

[0022] In this embodiment of the application, when the satellite type changes, the phase-locked loop bandwidth is linearly interpolated within a preset transition time window, and the Kalman filter weights are adjusted, including:

[0023] When the satellite type changes from a low-Earth orbit satellite to a medium-Earth orbit satellite, the phase-locked loop bandwidth corresponding to the low-Earth orbit satellite is adjusted to the phase-locked loop bandwidth corresponding to the medium-Earth orbit satellite through linear interpolation within a preset transition time window, and the Kalman filter weight corresponding to the low-Earth orbit satellite is adjusted to the Kalman filter weight corresponding to the medium-Earth orbit satellite based on preset weights.

[0024] When the satellite type changes from a medium Earth orbit satellite to a low Earth orbit satellite, the phase-locked loop bandwidth corresponding to the medium Earth orbit satellite is adjusted to the phase-locked loop bandwidth corresponding to the low Earth orbit satellite through linear interpolation within a preset transition time window, and the Kalman filter weights corresponding to the medium Earth orbit satellite are adjusted to the Kalman filter weights corresponding to the low Earth orbit satellite based on preset weights.

[0025] In this embodiment of the application, linear interpolation of the phase-locked loop bandwidth within a preset transition time window includes:

[0026] Based on a linear interpolation formula, the bandwidth of the phase-locked loop is linearly interpolated within a preset transition time window. The linear interpolation formula includes:

[0027]

[0028] in, This represents the bandwidth of the phase-locked loop (PLL) performing linear interpolation. This indicates the phase-locked loop bandwidth before the satellite type changed. Indicates the target phase-locked loop bandwidth. T Indicates the preset transition time window. This indicates the time when the type of satellite began to change. This indicates the time when the type of satellite changed.

[0029] The second aspect of this application provides a device for acquiring and tracking low-Earth orbit and medium-Earth orbit satellites, the device comprising:

[0030] The acquisition module is used to acquire the satellite's orbital altitude and the Doppler rate of change of the satellite signal, wherein the satellite signal is transmitted by the satellite;

[0031] The first determining module is used to determine the type of satellite based on orbital altitude and Doppler variation rate, wherein the satellite type includes low-Earth orbit satellites and medium-Earth orbit satellites;

[0032] The second determination module is used to determine the acquisition parameters and tracking loop parameters corresponding to the satellite based on the satellite type.

[0033] The acquisition module is used to acquire satellites according to acquisition parameters, including Doppler search step size and coherent integration time. The Doppler search step size corresponding to low-Earth orbit satellites is greater than that corresponding to medium-Earth orbit satellites, and the coherent integration time corresponding to low-Earth orbit satellites is less than that corresponding to medium-Earth orbit satellites.

[0034] The tracking module is used to set the tracking loop according to the tracking loop parameters to track satellites. The tracking loop parameters include Kalman filter weights, phase-locked loop bandwidth, and frequency-locked loop bandwidth. The Kalman filter weights corresponding to low-Earth orbit (LEO) satellites are greater than those corresponding to medium-Earth orbit (MEO) satellites. The phase-locked loop bandwidths corresponding to LEO satellites are greater than those corresponding to MEO satellites. The frequency-locked loop bandwidths corresponding to LEO satellites are greater than those corresponding to MEO satellites.

[0035] A third aspect of this application provides an acquisition and tracking device for low-Earth orbit and medium-Earth orbit satellites, comprising:

[0036] The memory is configured to store instructions;

[0037] The processor is configured to retrieve instructions from memory and, when executing the instructions, to implement the acquisition and tracking method for low-Earth orbit and medium-Earth orbit satellites as described in the first aspect above.

[0038] A fourth aspect of this application provides a machine-readable storage medium storing instructions for causing a machine to perform a method for capturing and tracking low-Earth orbit and medium-Earth orbit satellites as described in the first aspect above.

[0039] The above technical solutions adjust the acquisition parameters of the satellite navigation receiver for different satellite types to quickly acquire low-Earth orbit (LEO) satellite signals and reduce the acquisition time of medium-Earth orbit (MEO) satellite signals. They also adjust the tracking loop parameters of the satellite navigation receiver for different satellite types to improve the tracking stability of LEO satellite signals with high-speed dynamic characteristics while ensuring the tracking accuracy of MEO satellite signals.

[0040] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0041] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings:

[0042] Figure 1 The illustration shows a flowchart of a method for capturing and tracking low-Earth orbit and medium-Earth orbit satellites according to an embodiment of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0044] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application all comply with relevant laws and regulations. In the embodiments of this application, certain existing industry solutions such as software, components, and models may be mentioned. These should be considered exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions.

[0045] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0046] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0047] To better illustrate the acquisition and tracking method for low-Earth orbit and medium-Earth orbit satellites provided in this embodiment of the invention, the relevant characteristics of low-Earth orbit and medium-Earth orbit satellites are briefly described.

[0048] Low-Earth orbit (LEO) satellites move very fast relative to the receiver (angular velocity can reach 5-10 degrees / second), resulting in a large and rapidly changing Doppler frequency shift in the satellite signal (Doppler change rate can reach over 500 Hz / s). In contrast, medium-Earth orbit (MEO) satellites move slowly relative to the receiver (angular velocity approximately 0.5-1 degrees / second), and the Doppler change rate of their satellite signals is typically less than 50 Hz / s. Therefore, there is a difference in the dynamic characteristics of LEO and MEO satellites, with LEO satellites exhibiting high-speed dynamic characteristics.

[0049] Because of their low orbital altitude, low-Earth orbit (LEO) satellites experience less signal propagation loss, resulting in signal strength typically 20-30 dB higher than medium-Earth orbit (MEO) satellites. However, LEO satellites have shorter visibility windows (usually only a few minutes), while MEO satellites have longer visibility windows (several hours). Therefore, there is a difference in signal strength between LEO and MEO satellites, with MEO satellites exhibiting weaker signal characteristics.

[0050] Low Earth orbit (LEO) satellites have short visibility windows due to their low orbital altitude, but a large number of satellites in a constellation, leading to frequent satellite replacements. Medium Earth orbit (MEO) satellites have long visibility windows, but a relatively smaller number of satellites. Traditional satellite navigation receivers are typically optimized for MEO satellites when designing their acquisition and tracking loops, using fixed parameter settings (such as fixed Doppler search step size, phase-locked loop bandwidth, and frequency-locked loop bandwidth). When these fixed parameter settings are applied to LEO satellites, the following problems arise:

[0051] During the acquisition phase, due to the rapid Doppler change rate of low-Earth orbit (LEO) satellites, traditional fixed-step search strategies cannot quickly acquire satellite signals, resulting in excessively long acquisition times and even missing brief visibility windows. During the tracking phase, the bandwidth settings of traditional phase-locked loops (PLLs) and frequency-locked loops (FLLs) cannot simultaneously adapt to the high-speed dynamic characteristics of LEO satellites and the weak signal characteristics of medium-Earth orbit (MEO) satellites. Excessively wide PLL bandwidth introduces excessive noise when tracking MEO satellites, reducing tracking accuracy. Conversely, excessively narrow PLL bandwidth cannot track the high-speed dynamic characteristics of LEO satellites, leading to loss of lock. In other words, the acquisition and tracking loop parameter settings of traditional satellite navigation receivers cannot efficiently acquire and track both LEO and MEO satellites simultaneously in a mixed constellation environment.

[0052] Based on the aforementioned technical shortcomings Figure 1 This illustration schematically shows a flowchart of a method for acquiring and tracking low-Earth orbit and medium-Earth orbit satellites according to an embodiment of this application. Figure 1 As shown in the figure, this application provides a method for acquiring and tracking low-Earth orbit satellites and medium-Earth orbit satellites, which may include the following steps:

[0053] Step S110: Obtain the satellite's orbital altitude and the Doppler rate of change of the satellite signal, wherein the satellite signal is transmitted by the satellite;

[0054] Step S120: Determine the type of satellite based on orbital altitude and Doppler variation rate, wherein the satellite type includes low-Earth orbit satellites and medium-Earth orbit satellites;

[0055] Step S130: Based on the satellite type, determine the acquisition parameters and tracking loop parameters corresponding to the satellite;

[0056] Step S140: Capture the satellite according to the acquisition parameters, wherein the acquisition parameters include the Doppler search step size and the coherent integration time. The Doppler search step size corresponding to the low-Earth orbit satellite is greater than the Doppler search step size corresponding to the medium-Earth orbit satellite, and the coherent integration time corresponding to the low-Earth orbit satellite is less than the coherent integration time corresponding to the medium-Earth orbit satellite.

[0057] Step S150: Set the tracking loop according to the tracking loop parameters to track the satellite. The tracking loop parameters include Kalman filter weights, phase-locked loop bandwidth, and frequency-locked loop bandwidth. The Kalman filter weights corresponding to low-Earth orbit (LEO) satellites are greater than those corresponding to medium-Earth orbit (MEO) satellites. The phase-locked loop bandwidths corresponding to LEO satellites are greater than those corresponding to MEO satellites. The frequency-locked loop bandwidths corresponding to LEO satellites are greater than those corresponding to MEO satellites.

[0058] In step S110, the satellite's orbital altitude characterizes the average vertical distance of the satellite from the Earth's surface in its operational orbit, and the Doppler rate of change characterizes the first derivative of the Doppler frequency of the satellite signal measured by the satellite navigation receiver through the carrier tracking loop. Specifically, the satellite's ephemeris data is obtained by parsing the satellite navigation message, and the satellite's position in the ECEF (Earth-Centered, Earth-Fixed) coordinate system is calculated based on the ephemeris data, thereby calculating the satellite's orbital altitude. The formula for calculating the satellite's orbital altitude includes:

[0059]

[0060] In the formula, Indicates the satellite's orbital altitude. Indicates the satellite's position in the ECEF coordinate system. This represents the Earth's radius.

[0061] In step S120, based on the values ​​of orbital altitude and Doppler rate of change, it can be determined whether the satellite is a low-Earth orbit satellite or a medium-Earth orbit satellite.

[0062] In step S130, the acquisition parameters and tracking loop parameters of the satellite navigation receiver corresponding to the satellite are determined according to the type of satellite. That is, there are different sets of acquisition parameters and tracking loop parameters for low-Earth orbit satellites and medium-Earth orbit satellites, respectively.

[0063] In step S140, acquisition parameters corresponding to low-Earth orbit (LEO) satellites are used to acquire LEO satellites, and acquisition parameters corresponding to medium-Earth orbit (MEO) satellites are used to acquire MEO satellites. Schematic, the Doppler search step size corresponding to LEO satellites is dynamically decreased, with an initial Doppler search step size of 50 Hz / ms and a coherent integration time of 1 ms. The Doppler search step size corresponding to MEO satellites is a fixed value of 5 Hz / ms, and the coherent integration time is 20 ms. To optimize the high-speed dynamic characteristics of LEO satellites, a large Doppler search step size and a short coherent integration time are used. To optimize the weak signal characteristics of MEO satellites, a small Doppler search step size and a long coherent integration time are used. The Doppler search step size corresponding to LEO satellites is dynamically decreased according to the calculation formula for the Doppler search step size of LEO satellites. The calculation formula for the Doppler search step size of LEO satellites includes:

[0064]

[0065] In the formula, This indicates the current Doppler search step size. This represents the initial Doppler search step size. Indicates the attenuation coefficient. Indicates the search duration. This represents the minimum Doppler search step size threshold. Schematably, the attenuation coefficient is... The minimum Doppler search step size threshold is The formula for calculating the Doppler search step size for low-Earth orbit (LEO) satellites employs exponential decay and a lower threshold constraint to limit the LEO satellite's Doppler search step size to a certain range. above.

[0066] In step S150, the tracking loop for the low-Earth orbit (LEO) satellite is set using the tracking loop parameters corresponding to the LEO satellite to track it; similarly, the tracking loop for the medium-Earth orbit (MEO) satellite is set using the tracking loop parameters corresponding to the MEO satellite to track it. The tracking loop includes a carrier tracking loop and a code tracking loop. Schematic, the phase-locked loop (PLL) bandwidth corresponding to the LEO satellite is 15Hz, the frequency-locked loop (FLL) bandwidth is 10Hz, the PLL bandwidth corresponding to the MEO satellite is 3Hz, and the FLL bandwidth corresponding to the MEO satellite is 2Hz. To optimize the high-speed dynamic characteristics of LEO satellites, a wide PLL bandwidth is used. However, an excessively wide PLL bandwidth would introduce excessive noise when tracking MEO satellites; therefore, a narrow PLL bandwidth is used to suppress noise.

[0067] In this embodiment, the received satellite signal is distinguished in real time from low-Earth orbit (LEO) satellites or medium-Earth orbit (MEO) satellites. The acquisition parameters of the satellite navigation receiver are adaptively adjusted for different satellite types to quickly acquire LEO satellite signals and reduce the acquisition time of MEO satellite signals. The tracking loop parameters of the satellite navigation receiver are also adaptively adjusted for different satellite types. While ensuring the tracking accuracy of MEO satellite signals, the tracking stability of LEO satellite signals with high-speed dynamic characteristics is improved.

[0068] In one optional implementation, step S120 includes the following steps:

[0069] Step S121: If the orbital altitude is less than or equal to the first preset threshold and the Doppler change rate is greater than or equal to the second preset threshold, determine that the satellite type is a low-Earth orbit satellite;

[0070] Step S122: If the orbital altitude is greater than the first preset threshold and less than or equal to the third preset threshold, and the Doppler change rate is less than the fourth preset threshold, the satellite type is determined to be a medium-Earth orbit satellite, wherein the fourth preset threshold is less than the second preset threshold.

[0071] In step S121, the first preset threshold is 2000 km, the second preset threshold is 500 Hz / s, the satellite type is a low-Earth orbit satellite when the orbital altitude is less than or equal to 2000 km and the Doppler change rate is greater than or equal to 500 Hz / s.

[0072] In step S122, the third preset threshold is 20,000 km and the fourth preset threshold is 50 Hz / s. When the orbital altitude is greater than 2,000 km and less than or equal to 20,000 km and the Doppler change rate is less than 50 Hz / s, the satellite type is a medium-Earth orbit satellite.

[0073] This application's embodiments accurately distinguish between low-Earth orbit (LEO) and medium-Earth orbit (MEO) satellites by using orbital altitude and Doppler variation rate.

[0074] In one optional implementation, the method further includes the following steps:

[0075] Step S210: Generate local pseudocode and carrier signal based on the acquisition parameters;

[0076] Step S220: Determine the peak value of the acquisition signal generated when acquiring the satellite based on the local pseudocode, carrier signal, and satellite signal;

[0077] Step S230: If the peak value of the acquired signal is greater than a preset threshold, the satellite acquisition is confirmed to be successful.

[0078] In step S210, a local pseudocode and a carrier signal are generated by capturing parameters. The local pseudocode is a pseudo-random sequence generated internally by the satellite navigation receiver, with the same structure as the pseudocode transmitted by the satellite (such as the GPS C / A code (Coarse Acquisition Code)). The carrier signal is an orthogonal carrier signal generated internally by the satellite navigation receiver, with the same frequency as the nominal carrier frequency.

[0079] In step S220, correlation operations are performed using the local pseudocode, carrier signal, and satellite signal. Specifically, these operations include carrier stripping and code correlation. Carrier stripping: The satellite signal is multiplied by a locally generated carrier signal of the same frequency and phase (usually a complex exponential signal, such as cosine (cosine) or sine (sinine)) to remove the carrier and obtain the baseband signal. Code correlation: The carrier-stripped signal is correlated with the local pseudocode (locally generated PRN code, typically a dot product or convolution operation) to obtain the acquisition signal. When the local pseudocode and the code in the satellite signal are phase-aligned and their Doppler shifts are close, a peak value appears in the acquisition signal. This peak value indicates that a satellite signal may have been detected.

[0080] In step S230, during satellite acquisition, the success of satellite acquisition is determined by comparing the peak value of the acquisition signal with a preset threshold. If the peak value of the acquisition signal is greater than the preset threshold, satellite acquisition is successful; if the peak value is less than or equal to the preset threshold, satellite acquisition fails. Schematic, the preset threshold for low-Earth orbit satellites is the same as that for medium-Earth orbit satellites.

[0081] In one optional implementation, if the carrier-to-noise ratio of a low-Earth orbit satellite decreases by a preset bandwidth threshold, the low-Earth orbit satellite is reacquired; if a medium-Earth orbit satellite is lost lock for a preset number of consecutive times, the medium-Earth orbit satellite is reacquired.

[0082] In this embodiment, the low-Earth orbit (LEO) satellite is reacquired when its carrier-to-noise ratio (CNR) drops by 6 dB. The preset bandwidth threshold of 6 dB is an optimized value derived from a comprehensive consideration of the LEO satellite's dynamic characteristics, signal attenuation model, and real-time requirements, and has undergone extensive scenario testing. The medium-Earth orbit (MEO) satellite is reacquired after three consecutive loss of lock-on.

[0083] In one optional implementation, the acquisition parameters further include Doppler search range, incoherent accumulation count, and code phase search step size. The tracking loop parameters include data bit synchronization tolerance. Specifically, the absolute value of the Doppler search range corresponding to the low-Earth orbit (LEO) satellite is greater than the absolute value of the Doppler search range corresponding to the medium-Earth orbit (MEO) satellite; the incoherent accumulation count corresponding to the LEO satellite is greater than the incoherent accumulation count corresponding to the MEO satellite; the code phase search step size corresponding to the LEO satellite is greater than the code phase search step size corresponding to the MEO satellite; and the absolute value of the data bit synchronization tolerance corresponding to the LEO satellite is greater than the absolute value of the data bit synchronization tolerance corresponding to the MEO satellite.

[0084] In this embodiment, the absolute value of the Doppler search range corresponding to the low-Earth orbit (LEO) satellite is ±100kHz, the number of incoherent accumulations corresponding to the LEO satellite is 8, the code phase search step size corresponding to the LEO satellite is 1 / 2 chip (a coarser code phase search step size to speed up the search for LEO satellites), the Kalman filter weight corresponding to the LEO satellite is 0.9, and the data bit synchronization tolerance corresponding to the LEO satellite is ±0.25 chip. The absolute value of the Doppler search range corresponding to the medium-Earth orbit (MEO) satellite is ±10kHz, the number of incoherent accumulations corresponding to the MEO satellite is 1, the code phase search step size corresponding to the MEO satellite is 1 / 10 chip (a finer code phase search step size to accurately search for MEO satellites), the Kalman filter weight corresponding to the MEO satellite is 0.6, and the data bit synchronization tolerance corresponding to the MEO satellite is ±0.1 chip.

[0085] In one optional implementation, the method further includes the following steps:

[0086] Step S310: Based on orbital altitude and Doppler variation rate, determine whether the satellite type has changed;

[0087] Step S320: When the satellite type changes, linearly interpolate the phase-locked loop bandwidth within a preset transition time window and adjust the Kalman filter weights.

[0088] In this embodiment, during satellite tracking, the satellite type is monitored in real time for changes based on orbital altitude and Doppler rate of change (steps S121-S122 above). If the satellite type changes, the phase-locked loop bandwidth is linearly interpolated within a preset transition time window, and the Kalman filter weights are adjusted to ensure a smooth transition during orbit switching.

[0089] In one optional implementation, step S320 includes the following steps:

[0090] Step S321: When the satellite type changes from a low-Earth orbit satellite to a medium-Earth orbit satellite, within a preset transition time window, the phase-locked loop bandwidth corresponding to the low-Earth orbit satellite is adjusted to the phase-locked loop bandwidth corresponding to the medium-Earth orbit satellite through linear interpolation, and the Kalman filter weight corresponding to the low-Earth orbit satellite is adjusted to the Kalman filter weight corresponding to the medium-Earth orbit satellite based on preset weights.

[0091] Step S322: When the satellite type changes from a medium-Earth orbit satellite to a low-Earth orbit satellite, within a preset transition time window, the phase-locked loop bandwidth corresponding to the medium-Earth orbit satellite is adjusted to the phase-locked loop bandwidth corresponding to the low-Earth orbit satellite through linear interpolation, and the Kalman filter weights corresponding to the medium-Earth orbit satellite are adjusted to the Kalman filter weights corresponding to the low-Earth orbit satellite based on preset weights.

[0092] In this embodiment, the preset transition time window can be set to 100ms or 200ms. This embodiment does not make a specific limitation. The following will explain steps S321-S322 with the preset transition time window set to 200ms.

[0093] In step S321, when the satellite type changes from a low-Earth orbit (LEO) satellite to a medium-Earth orbit (MEO) satellite, within a preset transition time window of 200ms, the PLL bandwidth corresponding to the LEO satellite (15Hz) is adjusted to the PLL bandwidth corresponding to the MEO satellite (3Hz) through linear interpolation. Furthermore, based on preset weights, the Kalman filter weight corresponding to the LEO satellite (0.9) is adjusted to the Kalman filter weight corresponding to the MEO satellite (0.6). The LEO bandwidth changes from 15Hz to 11.4Hz to 7.2Hz to 3Hz during the adjustment process, and the Kalman filter weight changes from 0.9 to 0.84 to 0.72 to 0.6, where 0.72 and 0.84 are preset weights.

[0094] In step S322, when the satellite type changes from a medium Earth orbit (MEO) satellite to a low Earth orbit (LEO) satellite, within a preset transition time window of 200ms, the phase-locked loop (PLL) bandwidth corresponding to the MEO satellite (3Hz) is adjusted to the PLL bandwidth corresponding to the LEO satellite (15Hz) through linear interpolation. Furthermore, based on preset weights, the Kalman filter weight corresponding to the MEO satellite (0.6) is adjusted to the Kalman filter weight corresponding to the LEO satellite (0.9). The changes in the PLL bandwidth during the adjustment process are: 3Hz → 7.2Hz → 11.4Hz → 15Hz, and the changes in the Kalman filter weight are: 0.6 → 0.72 → 0.84 → 0.9.

[0095] In an optional implementation, step S320 further includes the following step:

[0096] Step S323: Based on the linear interpolation formula, perform linear interpolation on the phase-locked loop bandwidth within a preset transition time window, wherein the linear interpolation formula includes:

[0097]

[0098] in, This represents the bandwidth of the phase-locked loop (PLL) performing linear interpolation. This indicates the phase-locked loop bandwidth before the satellite type changed. Indicates the target phase-locked loop bandwidth. T Indicates the preset transition time window. This indicates the time when the type of satellite began to change. This indicates the time when the type of satellite changed.

[0099] In step S323, the phase-locked loop bandwidth is linearly interpolated within a preset transition time window using a linear interpolation formula to ensure a smooth transition for the satellite during orbit switching.

[0100] The following specific embodiment details a method for acquiring and tracking low-Earth orbit and medium-Earth orbit satellites provided in this application:

[0101] After the receiver starts up, it first acquires visible satellites. For each satellite, its orbital altitude is calculated using ephemeris data, and its Doppler rate of change is measured. The satellite type is determined based on the orbital altitude and Doppler rate of change. If a satellite's orbital altitude is 1200 km and its Doppler rate of change is 600 Hz / s, it is identified as a low-Earth orbit (LEO) satellite. The acquisition parameters corresponding to LEO satellites are used to acquire the LEO satellite. After successful acquisition, the tracking phase begins, using the tracking loop parameters corresponding to LEO satellites to track the LEO satellite. When the LEO satellite leaves the field of view and an unknown satellite enters the field of view, its orbital altitude is calculated and its Doppler rate of change is measured. If the orbital altitude is 21500 km and the Doppler rate of change is 30 Hz / s, the satellite is identified as a medium-Earth orbit (MEO) satellite. The acquisition parameters corresponding to MEO satellites are used to acquire the MEO satellite. After successful acquisition, the tracking phase begins, using the tracking loop parameters corresponding to MEO satellites to track the MEO satellite. During tracking, if the satellite changes from a medium Earth orbit satellite to a low Earth orbit satellite (e.g., due to receiver movement or changes in satellite orbit), a smooth switching mechanism is activated: within a preset transition time window, the phase-locked loop bandwidth is gradually increased from 3Hz to 15Hz, while the weights of the Kalman filter are adjusted by linear interpolation.

[0102] This application provides a method for acquiring and tracking low-Earth orbit (LEO) and medium-Earth orbit (MEO) satellites. This method dynamically adjusts acquisition and tracking loop parameters based on the real-time identified satellite type to adapt to mixed constellation environments. By increasing the Doppler search step size and shortening the coherent integration time, the acquisition speed of LEO satellites is significantly improved, reducing the acquisition time from 2.8 seconds in traditional methods to 0.6 seconds, an improvement of 78%. By reducing the phase-locked loop (PLL) bandwidth and frequency-locked loop (FLL) bandwidth, phase noise in MEO satellite tracking is reduced, decreasing the tracking phase error from 0.15 rad to 0.06 rad, an improvement of 60%. During satellite type switching, linear interpolation using the PLL bandwidth smoothly switches satellite types and reduces loss of lock, lowering the switching loss rate from 23% to below 1%. This application embodiment can be implemented on existing receiver software through algorithm upgrades without incurring additional hardware costs.

[0103] Optionally, embodiments of this application also provide a device for acquiring and tracking low-Earth orbit and medium-Earth orbit satellites, the device comprising:

[0104] The acquisition module is used to acquire the satellite's orbital altitude and the Doppler rate of change of the satellite signal, wherein the satellite signal is transmitted by the satellite;

[0105] The first determining module is used to determine the type of satellite based on orbital altitude and Doppler variation rate, wherein the satellite type includes low-Earth orbit satellites and medium-Earth orbit satellites;

[0106] The second determination module is used to determine the acquisition parameters and tracking loop parameters corresponding to the satellite based on the satellite type.

[0107] The acquisition module is used to acquire satellites according to acquisition parameters, including Doppler search step size and coherent integration time. The Doppler search step size corresponding to low-Earth orbit satellites is greater than that corresponding to medium-Earth orbit satellites, and the coherent integration time corresponding to low-Earth orbit satellites is less than that corresponding to medium-Earth orbit satellites.

[0108] The tracking module is used to set the tracking loop according to the tracking loop parameters to track satellites. The tracking loop parameters include Kalman filter weights, phase-locked loop bandwidth, and frequency-locked loop bandwidth. The Kalman filter weights corresponding to low-Earth orbit (LEO) satellites are greater than those corresponding to medium-Earth orbit (MEO) satellites. The phase-locked loop bandwidths corresponding to LEO satellites are greater than those corresponding to MEO satellites. The frequency-locked loop bandwidths corresponding to LEO satellites are greater than those corresponding to MEO satellites.

[0109] It is understood that the low-Earth orbit and medium-Earth orbit satellite acquisition and tracking device provided in this application embodiment can realize each process of the above-mentioned low-Earth orbit and medium-Earth orbit satellite acquisition and tracking method and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0110] Optionally, embodiments of this application also provide a device for acquiring and tracking low-Earth orbit and medium-Earth orbit satellites, comprising:

[0111] The memory is configured to store instructions;

[0112] The processor is configured to retrieve instructions from memory and, when executing instructions, to implement the acquisition and tracking methods for low-Earth orbit and medium-Earth orbit satellites as described above.

[0113] It is understood that the low-Earth orbit and medium-Earth orbit satellite acquisition and tracking equipment provided in this application embodiment can realize each process of the above-mentioned low-Earth orbit and medium-Earth orbit satellite acquisition and tracking method and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0114] Optionally, embodiments of this application also provide a machine-readable storage medium storing instructions for causing a machine to execute the acquisition and tracking method for low-Earth orbit and medium-Earth orbit satellites as described above.

[0115] It is understood that the machine-readable storage medium provided in the embodiments of this application can implement each process of the above-described low-Earth orbit and medium-Earth orbit satellite acquisition and tracking method and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0116] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0117] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0118] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0119] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0120] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0121] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0122] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0123] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0124] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for acquiring and tracking low-Earth orbit (LEO) and medium-Earth orbit (MEO) satellites, characterized in that, The method comprises: acquiring an orbital height of a satellite and a Doppler rate of change of a satellite signal, wherein the satellite signal is transmitted by the satellite; determining a type of the satellite based on the orbital height and the Doppler rate of change, wherein the type of the satellite comprises a low-orbit satellite and a medium-orbit satellite; determining acquisition parameters and tracking loop parameters corresponding to the satellite based on the type of the satellite; acquiring the satellite according to the acquisition parameters, wherein the acquisition parameters comprise a Doppler search step and a coherent integration time, the Doppler search step corresponding to the low-orbit satellite is greater than the Doppler search step corresponding to the medium-orbit satellite, and the coherent integration time corresponding to the low-orbit satellite is less than the coherent integration time corresponding to the medium-orbit satellite; setting a tracking loop according to the tracking loop parameters to track the satellite, wherein the tracking loop parameters comprise Kalman filter weights, a phase-locked loop bandwidth and a frequency-locked loop bandwidth, the Kalman filter weights corresponding to the low-orbit satellite are greater than the Kalman filter weights corresponding to the medium-orbit satellite, the phase-locked loop bandwidth corresponding to the low-orbit satellite is greater than the phase-locked loop bandwidth corresponding to the medium-orbit satellite, and the frequency-locked loop bandwidth corresponding to the low-orbit satellite is greater than the frequency-locked loop bandwidth corresponding to the medium-orbit satellite.

2. The method of claim 1, wherein, The determining of the type of the satellite based on the orbital height and the Doppler rate of change comprises: in a case where the orbital height is less than or equal to a first preset threshold and the Doppler rate of change is greater than or equal to a second preset threshold, determining that the type of the satellite is the low-orbit satellite; in a case where the orbital height is greater than the first preset threshold and less than or equal to a third preset threshold and the Doppler rate of change is less than a fourth preset threshold, determining that the type of the satellite is the medium-orbit satellite, wherein the fourth preset threshold is less than the second preset threshold.

3. The method of claim 1, wherein, The method further comprises: generating a local pseudo code and a carrier signal according to the acquisition parameters; determining a peak value of an acquisition signal generated when the satellite is acquired based on the local pseudo code, the carrier signal and the satellite signal; in a case where the peak value of the acquisition signal is greater than a preset threshold, determining that the satellite is acquired successfully.

4. The method of claim 1, wherein, The acquisition parameters further comprise a Doppler search range, a number of non-coherent accumulations and a code phase search step, and the tracking loop parameters comprise a data bit synchronization tolerance, wherein an absolute value of the Doppler search range corresponding to the low-orbit satellite is greater than an absolute value of the Doppler search range corresponding to the medium-orbit satellite, the number of non-coherent accumulations corresponding to the low-orbit satellite is greater than the number of non-coherent accumulations corresponding to the medium-orbit satellite, the code phase search step corresponding to the low-orbit satellite is greater than the code phase search step corresponding to the medium-orbit satellite, and an absolute value of the data bit synchronization tolerance corresponding to the low-orbit satellite is greater than an absolute value of the data bit synchronization tolerance corresponding to the medium-orbit satellite.

5. The method of claim 1, wherein, The method further comprises: determining whether the type of the satellite changes based on the orbital height and the Doppler rate of change; In the case that the type of the satellite changes, the phase-locked loop bandwidth is linearly interpolated within a preset transition time window, and the Kalman filter weight is adjusted.

6. The method of claim 5, wherein, The linear interpolation of the phase-locked loop bandwidth within the preset transition time window comprises: In the case that the type of the satellite changes from the low-orbit satellite to the medium-orbit satellite, the phase-locked loop bandwidth corresponding to the low-orbit satellite is adjusted to the phase-locked loop bandwidth corresponding to the medium-orbit satellite through linear interpolation within the preset transition time window, and the Kalman filter weight corresponding to the low-orbit satellite is adjusted to the Kalman filter weight corresponding to the medium-orbit satellite based on a preset weight. In the case that the type of the satellite changes from the medium-orbit satellite to the low-orbit satellite, the phase-locked loop bandwidth corresponding to the medium-orbit satellite is adjusted to the phase-locked loop bandwidth corresponding to the low-orbit satellite through linear interpolation within the preset transition time window, and the Kalman filter weight corresponding to the medium-orbit satellite is adjusted to the Kalman filter weight corresponding to the low-orbit satellite based on the preset weight.

7. The method of claim 5, wherein, The linear interpolation of the phase-locked loop bandwidth within the preset transition time window comprises: The linear interpolation of the phase-locked loop bandwidth within the preset transition time window comprises: wherein, denotes a phase-locked loop bandwidth performing linear interpolation, denotes a phase-locked loop bandwidth before a type of the satellite changes, denotes a target phase-locked loop bandwidth, T denotes the preset transition time window, denotes a time when a type of the satellite starts to change, denotes a time when a type of the satellite changes.

8. A low earth orbit satellite and medium earth orbit satellite acquisition tracking apparatus, characterized by, The apparatus comprises: The acquisition module is configured to acquire an orbit height of a satellite and a Doppler rate of variation of a satellite signal, wherein the satellite signal is transmitted by the satellite. The first determination module is configured to determine a type of the satellite based on the orbit height and the Doppler rate of variation, wherein the type of the satellite comprises a low-orbit satellite and a medium-orbit satellite. The second determination module is configured to determine acquisition parameters and tracking loop parameters corresponding to the satellite based on the type of the satellite. The acquisition module is configured to acquire an orbit height of a satellite and a Doppler rate of variation of a satellite signal, wherein the satellite signal is transmitted by the satellite. The tracking module is configured to set a tracking loop according to the tracking loop parameters and track the satellite, wherein the tracking loop parameters comprise a Kalman filter weight, a phase-locked loop bandwidth, and a frequency-locked loop bandwidth, the Kalman filter weight corresponding to the low-orbit satellite is greater than the Kalman filter weight corresponding to the medium-orbit satellite, the phase-locked loop bandwidth corresponding to the low-orbit satellite is greater than the phase-locked loop bandwidth corresponding to the medium-orbit satellite, and the frequency-locked loop bandwidth corresponding to the low-orbit satellite is greater than the frequency-locked loop bandwidth corresponding to the medium-orbit satellite.

9. A low earth orbit satellite and medium earth orbit satellite acquisition tracking apparatus, characterized by, The memory is configured to store instructions; The processor is configured to call the instructions from the memory and implement the acquisition and tracking method of the low-orbit satellite and the medium-orbit satellite according to any one of claims 1 to 7 when the instructions are executed. ​ 10. A machine-readable storage medium, characterized in that, The machine readable storage medium stores instructions for causing a machine to perform the method of capturing and tracking a low earth orbit satellite and a medium earth orbit satellite according to any one of claims 1 to 7.

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