Single GPS north-seeking method based on almanac constraint

Abstract

The invention provides a single GPS north-seeking method based on almanac constraint, a satellite terminal is configured with a single GPS antenna, and the method comprises the following steps: determining an estimated position of a satellite based on almanac information of the satellite; determining the current position of the satellite terminal by using a single GPS antenna; according to the satellite estimation position, the current position of the satellite terminal and the error range of the satellite estimation position, determining the variation range of the pitch angle of the satellite terminal under the geographic coordinate system; according to the candidate angle under the carrier coordinate system, determining a corresponding pitching angle under the geographic coordinate system; screening out an angle to be tested according to the change range of the pitch angle of the satellite terminal; communication between the satellite terminal and the satellite is simulated and constructed based on the to-be-tested angle, and course angle information of the satellite terminal is determined. The fast north-seeking method under the condition of miniaturization and low cost and under the condition of different carrier plane motion can be realized, and powerful technical guarantee is provided for follow-up stable satellite target tracking.

Description

Technical Field

[0001] The present invention relates to the technical field of low-orbit satellite communications, and in particular to a single GPS north-finding method based on almanac constraints. Background Art

[0002] In today's rapidly developing information society, the area and capacity of information interaction are increasing day by day. The installation of ground base stations is limited by many factors such as cost, location, and environment. It is difficult for signals to achieve global coverage. Many areas are weak signal areas or even signal blind areas. Satellite communications came into being to fill the signal blank areas, and gradually evolved from high-orbit synchronous satellites to low-orbit satellites. Due to their advantages such as low latency, low power consumption, and low cost, low-orbit satellites have attracted a large number of enterprises, research institutes, and enthusiasts to explore them in multiple directions. With the continuous establishment of low-orbit satellite constellations, the high-performance satellite transceiver terminals that match them have become key nodes in low-orbit satellite communications.

[0003] To achieve efficient low-orbit satellite communications, the terminal must maintain excellent tracking capabilities. This involves a key technology: acquiring the terminal's attitude information to effectively transform its orientation between different coordinate systems, thereby providing the parameters necessary for stable tracking. Currently, the attitude information required by the transceiver terminal is directly provided by a combined inertial navigation system (consisting of a pair of GPS antennas, a gyroscope, and an accelerometer). Heading angle information is provided by a pair of GPS antennas (often using RTK technology). Given the required angle accuracy, the GPS antenna baseline often needs to be extended to obtain highly accurate heading angle information.

[0004] Considering the need for subsequent miniaturization and low cost, it is desirable to obtain target heading information using a single GPS antenna. In GPS antenna mode, a single GPS antenna can only provide the carrier's position (with an accuracy of meters), but cannot obtain the required heading information. The conventional approach is to iterate through the output angles, confirming the target's accuracy through feedback (signal-to-noise ratio, signal strength, broadcast table information, etc.), and then calculate the terminal's heading information. This method requires iterating through all heading and pitch angles, resulting in a large number of beam positions. If time permits, these can be tried sequentially to determine the target's direction. However, this method is time-consuming and the north-finding response is not timely. Summary of the Invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art.

[0006] To this end, the present invention provides a single GPS north-finding method based on almanac constraints.

[0007] The present invention proposes a single GPS north-finding method based on almanac constraints, wherein the satellite terminal is equipped with a single GPS antenna, and the method comprises: Determining an estimated position of the satellite based on almanac information of the satellite, wherein the estimated position has an error with the actual position of the satellite; Determine the current location of the satellite terminal using a single GPS antenna; Determining a range of variation of the elevation angle of the satellite terminal in a geographic coordinate system based on the estimated satellite position, the current position of the satellite terminal, and an error range of the estimated satellite position; Determine the corresponding pitch angle in the geographic coordinate system based on the candidate angle in the carrier coordinate system; the candidate angle includes the pitch angle and heading angle of the satellite terminal; Selecting a candidate angle whose corresponding elevation angle in the geographic coordinate system is within the variation range of the elevation angle of the satellite terminal as the angle to be tested; The communication between the satellite terminal and the satellite is simulated based on the verification angle. Information feedback is used to confirm whether the satellite terminal is pointing to the target. The heading angle information of the satellite terminal is determined according to the verification angle corresponding to the satellite terminal pointing to the target.

[0008] The single GPS north-finding method based on almanac constraints according to the above technical solution of the present invention may also have the following additional technical features: In the above technical solution, the step of determining the range of variation of the satellite terminal's elevation angle in the geographic coordinate system based on the satellite estimated position, the current position of the satellite terminal, and the error range of the satellite estimated position includes: Calculate the pointing vector between the satellite and the satellite terminal in the ECEF coordinate system based on the current position of the satellite terminal and the estimated position of the satellite; By converting the ECEF coordinate system to the geographic coordinate system, the pointing vector in the geographic coordinate system is obtained, and thus the pitch angle corresponding to the pointing vector in the geographic coordinate system is obtained; By calculating the elevation angle corresponding to the pointing vector between the satellite terminal and any position on the error range boundary of the satellite estimated position, the variation range of the satellite terminal elevation angle in the geographic coordinate system is obtained.

[0009] In the above technical solution, the calculation of the pointing vector between the satellite and the satellite terminal in the ECEF coordinate system based on the current position of the satellite terminal and the estimated position of the satellite includes:

[0010] in, Indicates the estimated position of the satellite; Indicates the current position of the satellite terminal determined using a single GPS antenna; represents the pointing vector between the satellite and the satellite terminal in the ECEF coordinate system; The calculation method of the pitch angle corresponding to the pointing vector in the geographic coordinate system is:

[0011] in, Indicates the elevation angle corresponding to the pointing vector in the geographic coordinate system.

[0012] In the above technical solution, determining the corresponding pitch angle in the geographic coordinate system based on the candidate angle in the carrier coordinate system includes: Determine the rotation order from the carrier coordinate system to the geographic coordinate system; Determine the three-axis rotation matrix from the carrier coordinate system to the geographic coordinate system; Based on the transformation process of the pointing vector in the geographic coordinate system, a calculation method for the pitch angle corresponding to the candidate angle in the geographic coordinate system is determined.

[0013] In the above technical solution, the rotation order from the carrier coordinate system to the geographic coordinate system is roll, pitch, and heading.

[0014] In the above technical solution, the pitch angle corresponding to the candidate angle in the geographic coordinate system is calculated as follows:

[0015] in, Indicates the pitch angle corresponding to the candidate angle in the geographic coordinate system; pitch indicates the axis change angle in the pitch direction when the geographic coordinate system is transformed into the carrier coordinate system through the axis; roll indicates the axis change angle in the roll direction when the geographic coordinate system is transformed into the carrier coordinate system through the axis; Indicates the elevation angle of the satellite terminal in the candidate angle; Indicates the heading angle of the satellite terminal in the candidate angle; The axis variation angle in the pitch direction and the axis variation angle in the roll direction are measured and obtained by an accelerometer configured on the satellite terminal.

[0016] In the above technical solution, when the satellite terminal is in the moving communication operation mode, when the communication between the satellite terminal and the satellite is constructed based on the simulation of the angle to be verified, the three-axis change of the carrier plane between the current execution time of the angle to be verified and the initial time is considered, and the attitude compensation of the angle to be verified is performed based on the three-axis change of the carrier plane.

[0017] In the above technical solution, the posture compensation of the angle to be tested based on the three-axis change of the carrier plane includes: Using a gyroscope configured in the satellite terminal to measure the attitude change of the satellite terminal from the initial moment to the current execution moment of the angle to be verified; Based on the attitude change results measured by the gyroscope, a three-attitude change matrix is ​​constructed; The attitude compensation is performed on the tested angles based on the three-attitude change matrix.

[0018] In the above technical solution, the attitude change of the satellite terminal from the initial moment to the current verification angle execution moment includes the movement change of the satellite terminal itself in the moving communication operation mode and the attitude change introduced by the device pointing delay.

[0019] In the above technical solution, a plurality of candidate angles are judged to determine whether they meet the requirements of the angle to be tested, and a dataset of angles to be tested is constructed based on the candidate angles that meet the requirements of the angle to be tested; The heading angle information of the satellite terminal is determined by traversing the data set of angles to be verified; wherein, when traversing the data set of angles to be verified, the number of angles to be verified is compressed according to a set step.

[0020] In summary, due to the adoption of the above technical features, the beneficial effects of the present invention are: This invention leverages auxiliary information (such as almanac information, accelerometer, and gyroscope detection information) to effectively compress the search range and reduce the time required to acquire heading angles. The proposed algorithm is easy to implement and simple to operate. Specifically, this invention uses long-term almanac information combined with information from accelerometer sensors as constraints to propose a new method for rapidly acquiring a satellite's heading angle using a satellite receiving terminal.

[0021] Specifically, the search and screening process provided in this invention significantly reduces the number of orientations required to be traversed under statistical conditions, significantly shortening north-finding time. This process selects candidate angles based on conditions such as the elevation angle constraint in the almanac and the independence of the coordinate system transformation process from the heading angle. The present invention also analyzes the processing methods for traversing candidate angles under both static and dynamic motion modes to ensure north-finding accuracy.

[0022] The present invention can realize a fast north-seeking method under different carrier plane motion conditions under miniaturized and low-cost conditions, providing a strong technical guarantee for subsequent stable tracking of satellite targets.

[0023] Additional aspects and advantages of the invention will become apparent from the description which follows, or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 This is a flow chart of a single GPS north-finding method based on almanac constraints according to an embodiment of the present invention; Figure 2 The pitch angle range in the ECEF coordinate system in the single GPS north-finding method based on almanac constraints according to an embodiment of the present invention is as follows; Figure 3 The figure is a schematic diagram of the attitude change of the carrier plane in motion in a single GPS north-finding method based on almanac constraints according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0027] Refer to the following Figures 1 to 3 The following describes a single GPS north-finding method based on almanac constraints according to some embodiments of the present invention.

[0028] Some embodiments of the present application provide a single GPS north-finding method based on almanac constraints.

[0029] like Figure 1 As shown, the first embodiment of the present invention proposes a single-GPS north-finding method based on almanac constraints. This method assumes that the satellite terminal is equipped with only a single GPS antenna. Specifically, a miniaturized single-GPS satellite terminal is used as a transceiver, and a carrier coordinate system is established based on the carrier plane to which it belongs. By default, the signal is reachable within the carrier plane, meaning that low-orbit satellite signals can be received at a certain heading and pitch angle of the current carrier plane. The north-finding method includes the following steps S1-S6.

[0030] S1. Determine an estimated position of a satellite based on almanac information of the satellite, where there is an error between the estimated position and the actual position of the satellite.

[0031] Specifically, based on the prior long-term almanac information, the approximate position of the satellite can be derived through the orbital elements, and the orbital error accuracy is on the order of tens of kilometers.

[0032] In a specific embodiment, the six orbital elements and the rate of change of the ascending node accuracy given by the long-term almanac information can be extrapolated to obtain the estimated position and velocity information of the satellite at the current moment in the geographic coordinate system according to different orbit models. The specific method is well known to those skilled in the art and will not be described in detail here. Due to the influence of orbit extrapolation error and long-term almanac representation error, such as Figure 2 As shown, the estimated position of the satellite The heading error is about 50km (considering that the error is mainly caused by the x and y axes).

[0033] S2. Use a single GPS antenna to determine the current location of the satellite terminal.

[0034] S3. Determine a variation range of the satellite terminal's elevation angle in the geographic coordinate system based on the satellite estimated position, the current position of the satellite terminal, and an error range of the satellite estimated position.

[0035] Specifically, step S3 can determine the coverage heading and the maximum number of scanning layers of a single wave position through the search rules of the airspace, and based on this, the variation range of the pitch angle in the geographic coordinate system can be obtained and used as a constraint condition.

[0036] In some embodiments, step S3 includes: S31. Calculating a pointing vector between the satellite and the satellite terminal in the ECEF coordinate system based on the current position of the satellite terminal and the estimated position of the satellite; including:

[0037] in, Indicates the estimated position of the satellite; Indicates the current position of the satellite terminal determined using a single GPS antenna; represents the pointing vector between the satellite and the satellite terminal in the ECEF coordinate system; S32. Obtaining a pointing vector in the geographic coordinate system by converting the ECEF coordinate system into the geographic coordinate system, thereby obtaining a pitch angle corresponding to the pointing vector in the geographic coordinate system; including:

[0038] in, Indicates the elevation angle corresponding to the pointing vector in the geographic coordinate system.

[0039] S33. Calculate the elevation angle corresponding to the pointing vector between the satellite terminal and any position on the error range boundary of the estimated satellite position to obtain the range of variation of the satellite terminal elevation angle in the geographic coordinate system. Specifically, using the outer circle of the maximum error as a reference, the possible range of the true elevation angle of the satellite-terminal connection in the geographic coordinate system can be obtained. Figure 2 By calculating the pitch angle corresponding to the pointing vector at different error positions, the range of the true pitch angle can be obtained: ,in, and They are the minimum and maximum values ​​of the pitch angle in the geographic coordinate system, respectively. This value range can be used as the basis for judging the validity of the angle after subsequent inverse transformation.

[0040] S4. Determine the corresponding pitch angle in the geographic coordinate system based on the candidate angle in the carrier coordinate system; the candidate angle includes the pitch angle and heading angle of the satellite terminal.

[0041] It is understood that the set of candidate angles is the same as the output angles traversed in traditional solutions. The candidate angle set can be generated in a certain step-by-step and combination manner within the range of pitch and heading angles. To screen the candidate angles, the present disclosure first calculates the pitch angle corresponding to each candidate angle in the geographic coordinate system.

[0042] In some embodiments, step S4 includes: S41. Determine the rotation order from the carrier coordinate system to the geographic coordinate system.

[0043] According to the transformation order of Euler angles and the rotation order from the geographic coordinate system (ECEF coordinate system) to the carrier coordinate system, the rotation order from the carrier coordinate system to the geographic coordinate system is: roll - pitch - heading.

[0044] S42. Determine the three-axis rotation matrix from the carrier coordinate system to the geographic coordinate system.

[0045] Specifically, the rotation matrix corresponding to each axis is as follows:

[0046]

[0047]

[0048] Among them, yaw represents the axis change angle in the heading direction when the geographic coordinate system is changed to the carrier coordinate system through the axis; pitch represents the axis change angle in the pitch direction when the geographic coordinate system is changed to the carrier coordinate system through the axis; roll represents the axis change angle in the roll direction when the geographic coordinate system is changed to the carrier coordinate system through the axis.

[0049] S43. Based on the transformation process of the pointing vector in the geographic coordinate system, determine a calculation method for the pitch angle corresponding to the candidate angle in the geographic coordinate system.

[0050] Specifically, according to the rotation order and the rotation matrix, the pointing vector in the geographic coordinate system can be obtained as shown on the right side of the following equation:

[0051] Among them, X1-X8 represent unknown quantities related to yaw and do not affect the solution of the pitch angle corresponding to the candidate angle in the geographic coordinate system.

[0052] Based on the above formula, the calculation method of the pitch angle corresponding to the candidate angle in the geographic coordinate system is:

[0053] in, Indicates the pitch angle corresponding to the candidate angle in the geographic coordinate system; pitch indicates the axis change angle in the pitch direction when the geographic coordinate system is transformed into the carrier coordinate system through the axis; roll indicates the axis change angle in the roll direction when the geographic coordinate system is transformed into the carrier coordinate system through the axis; Indicates the elevation angle of the satellite terminal in the candidate angle; Indicates the heading angle of the satellite terminal in the candidate angle; Among them, the axis variation angle pitch in the pitch direction and the axis variation angle roll in the roll direction are obtained by measuring the accelerometer configured on the satellite terminal; the parameters given by the accelerometer sensor are based on the carrier plane, and the pitch angle information in the geographic coordinate system can be obtained by solving the above changes.

[0054] S5. Select a candidate angle whose corresponding elevation angle in the geographic coordinate system is within the variation range of the elevation angle of the satellite terminal as the angle to be verified.

[0055] Specifically, by determining the candidate angles corresponding to Whether it belongs to If the angle falls within the range, it will be retained as the angle to be verified; if it does not fall within the range, it will be eliminated without the need for subsequent verification.

[0056] S6. Simulate and establish communication between the satellite terminal and the satellite based on the to-be-verified angle, confirm whether the satellite terminal is pointing at the target through information feedback, and determine the heading angle information of the satellite terminal based on the to-be-verified angle corresponding to when the satellite terminal is pointing at the target.

[0057] Specifically, information from observable low-orbit satellites is used to determine the effectiveness of the pointing system. Feedback (such as signal-to-noise ratio, signal strength, and broadcast table information) is used to confirm whether the beam is aligned with the target. Heading angle information is then derived from the relationship between the changes in different coordinate systems. This verification process is well known to those skilled in the art and will not be elaborated on here.

[0058] It should be noted that, in some embodiments, the verification process needs to be differentiated according to the operation mode of the satellite terminal, wherein the operation mode of the satellite terminal is mainly divided into communication in motion and communication in stationary.

[0059] A static communication system is a device or system that can automatically find satellites at a fixed location and connect to the main network via satellite to establish a communication connection with the satellite station. It can only communicate with satellites in real time when it is stationary.

[0060] Mobile communication: that is, "satellite ground station communication system on the move", which means that mobile carriers such as vehicles, ships, and airplanes can track satellite platforms in real time during movement and continuously transmit multimedia information such as voice, data, and images.

[0061] To maintain full angle coverage, static communication only requires traversing the candidate angles sequentially through angle discrimination. Dynamic communication requires consideration of attitude compensation at different times during motion. Since the initial plane is used as the reference, changes in the carrier's attitude between different times and the initial moment must be considered (the gyroscope can directly determine the attitude change of the carrier plane through integration). Using the three-posture transformation matrix, candidate angles can be traversed sequentially.

[0062] In a specific embodiment, when the satellite terminal is in the communication-in-motion operation mode, when simulating the communication between the satellite terminal and the satellite based on the angle to be verified, the three-axis changes of the carrier plane between the execution time of the current angle to be verified and the initial time are considered. The change process is as follows: Figure 3 As shown in the figure, posture compensation is performed on the angle to be tested based on the three-axis change of the carrier plane.

[0063] Specifically, performing posture compensation on the angle to be tested based on the three-axis change of the carrier plane includes: Using a gyroscope configured in the satellite terminal to measure the attitude change of the satellite terminal from the initial moment to the current execution moment of the angle to be verified; Based on the attitude change results measured by the gyroscope, a three-attitude change matrix is ​​constructed; Perform posture compensation for the tested angle based on the three-posture change matrix; including:

[0064] in, , , This value represents the change in roll, pitch, and yaw angles when switching between different orientations, based on attitude changes measured by the gyroscope. This compensation ensures that the terminal's orientation is consistent with the initial loading plane.

[0065] In some embodiments, dramatic non-stationary changes also require consideration of the attitude change introduced by the satellite terminal's pointing delay. This means that the attitude change must be factored in based on the time delay. The attitude change from the initial moment to the current verification angle execution moment includes both the satellite terminal's own motion changes in the communication-in-motion mode and the attitude change introduced by the device's pointing delay.

[0066] In some embodiments, a plurality of candidate angles are judged to determine whether they meet the requirements of the angles to be verified, and a data set of angles to be verified is constructed based on the candidate angles that meet the requirements of the angles to be verified; the heading angle information of the satellite terminal is determined by traversing the data set of angles to be verified; wherein, when traversing the data set of angles to be verified, the number of angles to be verified is compressed according to a set step.

[0067] Specifically, since the beam coverage has a certain width, which is related to the frequency band and array type, the appropriate traversal step can be selected according to the actual situation, which can further compress the angle to be tested and reduce the time to obtain the terminal heading angle.

[0068] In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples.

[0069] Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A single GPS north-finding method based on almanac constraints, characterized in that: The satellite terminal is configured with a single GPS antenna, and the method includes: Determining an estimated position of the satellite based on almanac information of the satellite, wherein the estimated position has an error with the actual position of the satellite; Determine the current location of the satellite terminal using a single GPS antenna; Determining a range of variation of the elevation angle of the satellite terminal in a geographic coordinate system based on the estimated satellite position, the current position of the satellite terminal, and an error range of the estimated satellite position; Determine the corresponding pitch angle in the geographic coordinate system based on the candidate angle in the carrier coordinate system; the candidate angle includes the pitch angle and heading angle of the satellite terminal; Selecting a candidate angle whose corresponding elevation angle in the geographic coordinate system is within the variation range of the elevation angle of the satellite terminal as the angle to be tested; The communication between the satellite terminal and the satellite is simulated based on the verification angle. Information feedback is used to confirm whether the satellite terminal is pointing to the target. The heading angle information of the satellite terminal is determined according to the verification angle corresponding to the satellite terminal pointing to the target.

2. The single GPS north-finding method based on almanac constraints according to claim 1, characterized in that: The determining of a variation range of the satellite terminal pitch angle in a geographic coordinate system based on the satellite estimated position, the current position of the satellite terminal, and an error range of the satellite estimated position includes: Calculate the pointing vector between the satellite and the satellite terminal in the ECEF coordinate system based on the current position of the satellite terminal and the estimated position of the satellite; By converting the ECEF coordinate system to the geographic coordinate system, the pointing vector in the geographic coordinate system is obtained, and thus the pitch angle corresponding to the pointing vector in the geographic coordinate system is obtained; By calculating the elevation angle corresponding to the pointing vector between the satellite terminal and any position on the error range boundary of the satellite estimated position, the variation range of the satellite terminal elevation angle in the geographic coordinate system is obtained.

3. The single GPS north-finding method based on almanac constraints according to claim 2, characterized in that: The step of calculating a pointing vector between the satellite and the satellite terminal in the ECEF coordinate system based on the current position of the satellite terminal and the estimated position of the satellite includes: in, Indicates the estimated position of the satellite; Indicates the current position of the satellite terminal determined using a single GPS antenna; represents the pointing vector between the satellite and the satellite terminal in the ECEF coordinate system; The calculation method of the pitch angle corresponding to the pointing vector in the geographic coordinate system is: in, Indicates the elevation angle corresponding to the pointing vector in the geographic coordinate system.

4. The single GPS north-finding method based on almanac constraints according to claim 1, characterized in that: The determining, based on the candidate angle in the carrier coordinate system, the corresponding pitch angle in the geographic coordinate system includes: Determine the rotation order from the carrier coordinate system to the geographic coordinate system; Determine the three-axis rotation matrix from the carrier coordinate system to the geographic coordinate system; Based on the transformation process of the pointing vector in the geographic coordinate system, a calculation method for the pitch angle corresponding to the candidate angle in the geographic coordinate system is determined.

5. The single GPS north-finding method based on almanac constraints according to claim 4, characterized in that: The rotation order from the carrier coordinate system to the geographic coordinate system is roll, pitch, and heading.

6. The method for finding north using a single GPS based on almanac constraints according to claim 5, wherein: The calculation method of the pitch angle corresponding to the candidate angle in the geographic coordinate system is: in, Indicates the pitch angle corresponding to the candidate angle in the geographic coordinate system; pitch indicates the axis change angle in the pitch direction when the geographic coordinate system is transformed into the carrier coordinate system through the axis; roll indicates the axis change angle in the roll direction when the geographic coordinate system is transformed into the carrier coordinate system through the axis; Indicates the elevation angle of the satellite terminal in the candidate angle; Indicates the heading angle of the satellite terminal in the candidate angle; The axis variation angle in the pitch direction and the axis variation angle in the roll direction are measured and obtained by an accelerometer configured on the satellite terminal.

7. The method for finding north using a single GPS based on almanac constraints according to claim 1, wherein: When the satellite terminal is in the communication-in-motion operation mode, when constructing the communication between the satellite terminal and the satellite based on the simulation of the angle to be verified, the three-axis change of the carrier plane between the current execution time of the angle to be verified and the initial time is taken into account, and the attitude compensation of the angle to be verified is performed based on the three-axis change of the carrier plane.

8. The method for finding north using a single GPS based on almanac constraints according to claim 7, wherein: The performing posture compensation on the angle to be tested based on the three-axis change of the carrier plane includes: Using a gyroscope configured in the satellite terminal to measure the attitude change of the satellite terminal from the initial moment to the current execution moment of the angle to be verified; Based on the attitude change results measured by the gyroscope, a three-attitude change matrix is ​​constructed; The attitude compensation is performed on the tested angles based on the three-attitude change matrix.

9. The method for finding north using a single GPS based on almanac constraints according to claim 8, wherein: The attitude change of the satellite terminal from the initial moment to the current execution moment of the verification angle includes the movement change of the satellite terminal itself in the mobile communication operation mode and the attitude change introduced by the device pointing delay.

10. The single GPS north-finding method based on almanac constraints according to claim 1, characterized in that: Determine whether several candidate angles meet the requirements of the angle to be tested, and construct a dataset of angles to be tested based on the candidate angles that meet the requirements; The heading angle information of the satellite terminal is determined by traversing the data set of angles to be verified; wherein, when traversing the data set of angles to be verified, the number of angles to be verified is compressed according to a set step.

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