Compact low-cost GNSS direction finding method and system
By using a sy-clock dual-antenna board and ultra-short baseline in GNSS direction finding, and combining the proximal rounding method to calculate the ambiguity throughout the whole circumference, the problem of baseline length limitation of the traditional GNSS double-antenna direction finding method is solved, and high-precision direction finding of small carriers is achieved.
Patent Information
- Application Number
- CN202510069197.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-16
- Publication Date
- 2025-04-25
AI Technical Summary
Due to the limitation of baseline length, the traditional GNSS dual-antenna direction finding method has limited use environment and is difficult to meet the direction finding needs of small carriers.
The GNSS single frequency ultra-short baseline carrier phase observation measurement is used to receive the single difference between stations and single difference, and the ambiguity of the single difference is calculated by using the nearest rounding method. Finally, the carrier heading angle is solved by the trigonometric function relationship.
Implementing high-precision GNSS direction finding on small carriers reduces the requirements for hardware space and baseline length, reduces the amount of calculation, improves the ambiguity fixed rate, and is suitable for low-cost, low-computing and small-size platforms.
Smart Images
Figure CN119881998A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of satellite navigation technology, and in particular to a compact and low-cost GNSS direction-finding method. Background Art
[0002] GNSS (Global Navigation Satellite System) direction finding technology has become an important tool in the navigation field of various carriers (such as ocean, land, aviation and aerospace, etc.) due to its high accuracy and wide application scenarios. Its application range covers many fields from ordinary car navigation to precise drones, ship navigation, aircraft control, etc. The accuracy of GNSS direction finding technology mainly depends on the carrier phase measurement technology, and it can be divided into two basic methods: single antenna direction finding and dual antenna direction finding.
[0003] Among them, single-antenna direction finding is a relatively simple GNSS direction finding method, which uses the carrier phase epoch difference technology (Time Differenced Carrier Phase, TDCP) for measurement. By processing the carrier phase difference between two adjacent epochs, a virtual baseline can be obtained, and the direction of this virtual baseline is consistent with the velocity vector of the carrier. Therefore, the single-antenna direction finding technology actually reflects the direction of the carrier's motion trajectory by measuring the track angle (Track Angle). It should be noted that the track angle is not the same as the heading angle. It only describes the change in the direction of the carrier's motion, so it is also called the pseudo-heading angle. However, when a car on land is driving without drifting, the track angle is equal to the heading angle. Therefore, in the above situation, a single antenna can be used to calculate the track angle to approximately replace the heading angle. Of course, there are also some cases where the pseudo heading angle is completely unequal to the heading angle. For example, when the drone rotates in place, the direction of the virtual baseline cannot accurately reflect its heading angle because the velocity vector remains unchanged; when driving on a ship with a large current, the hull may be affected by the flow during navigation, and the virtual baseline will deviate, resulting in a difference between the heading angle and the track angle; when the car drifts, on a highway or other flat road, although the direction of movement of the vehicle is close to the direction of speed, the sensor or external conditions (such as wind speed or slippery road surface) may cause the track angle to deviate from the actual heading. If you want to obtain the true heading angle, two antennas should be installed. Usually, the baseline vector formed by the two antennas is consistent with the direction of the carrier's central axis. Since the direction-finding accuracy is proportional to the baseline length, the distance between the two antennas is often more than 1m to achieve a relatively high direction-finding accuracy. This has caused a significant limitation on the use scenario and requires the carrier to have a corresponding installation space.
[0004] Compared with the single-antenna direction finding technology, the dual-antenna direction finding technology can more accurately calculate the true heading angle of the carrier. Its core principle is to solve the baseline vector between the dual antennas and use this baseline vector to determine the actual direction of the carrier. Since the dual antennas can directly determine the heading angle of the carrier, the pseudo heading angle problem caused by the single antenna can be avoided. The key to the dual-antenna direction finding technology lies in the correct resolution of the integer ambiguity in the carrier phase differential positioning. Integer ambiguity is a common problem in the GNSS positioning process. It is caused by factors such as the multipath effect on the signal propagation path and the geometric position change between the satellite and the receiver. It is difficult to solve the integer ambiguity problem, especially in the case of short baselines. Accurately fixing the integer ambiguity is crucial to achieve high-precision positioning. The resolution of the integer ambiguity can be achieved using the Integer Bootstrapping (IB), the integer least squares search method, the LAMBDA method, and the Constrained Least-square Ambiguity Decorrelation Adjustment (CLAMBDA). Among them, LAMBDA is the most widely used, but because it requires a large number of ambiguity searches, the amount of calculation is relatively large. Summary of the invention
[0005] The present invention aims at the problem that the direction finding accuracy of the traditional GNSS dual-antenna direction finding is proportional to the baseline length. The longer the baseline, the higher the accuracy. Usually, an installation space of more than 1m is required. For some small carriers, it is not easy to meet this requirement. Therefore, a compact and low-cost GNSS direction finding method is proposed. The method comprises:
[0006] Receive GNSS single-frequency ultra-short baseline carrier phase observations using a common clock dual-antenna board and ultra-short baseline;
[0007] Construct inter-station differences based on carrier phase observations of ultra-short baselines;
[0008] Obtain the altitude and azimuth angles of all visible satellites based on the satellite ephemeris file and the approximate coordinates of the user;
[0009] Eliminate low altitude angle satellites according to the preset cut-off altitude angle;
[0010] The single-difference integer ambiguity is calculated by rounding to the nearest integer;
[0011] Calculate the baseline vector using the integer ambiguity results;
[0012] The carrier heading angle is solved through trigonometric function relationship.
[0013] Furthermore, a preferred embodiment is proposed, wherein the length of the ultra-short baseline is less than 0.5 weeks.
[0014] Furthermore, a preferred method is proposed, wherein the method of using a common clock dual-antenna board to receive GNSS single-frequency ultra-short baseline carrier phase observations comprises:
[0015] φi=ρ i +c(t-τi)-Ii+Ti+λNi+ε
[0016] Among them, φ is the carrier phase observation, ρ is the geometric distance, the superscript i is the satellite number, I is the ionospheric delay, T is the tropospheric delay, t is the receiver clock error, τ is the satellite clock error, N is the integer ambiguity, λ is the wavelength, and ε is the noise.
[0017] Furthermore, a preferred method is proposed, wherein the inter-station difference is constructed based on the carrier phase observation of the ultra-short baseline, including:
[0018]
[0019] Among them, the subscript r represents a mobile station, b represents a base station, and the subscript rb represents an inter-station single difference.
[0020] Furthermore, a preferred method is proposed, wherein the method of calculating the single-difference integer ambiguity by rounding to the nearest integer includes:
[0021]
[0022] Among them, [] indicates rounding.
[0023] Furthermore, a preferred method is proposed, wherein the method of calculating the baseline vector using the integer ambiguity result includes:
[0024]
[0025] [ΔxΔyΔz] T =(G T G) -1 G T b
[0026] Where G is the Jacobian matrix, [ΔxΔyΔz] T is the baseline vector.
[0027] Furthermore, a preferred method is proposed, wherein the method of solving the heading angle of the carrier by using a trigonometric function relationship comprises:
[0028]
[0029] Among them, α is the heading angle, Δe is the projection of the baseline vector in the east direction, and Δn is the projection of the baseline vector in the north direction.
[0030] Based on the same inventive concept, the present invention also proposes a compact and low-cost GNSS direction finding system, the system comprising:
[0031] A carrier phase observation acquisition unit, used for receiving GNSS single-frequency ultra-short baseline carrier phase observations using a common clock dual-antenna board and an ultra-short baseline;
[0032] An inter-station difference construction unit, used for constructing inter-station differences based on carrier phase observations of ultra-short baselines;
[0033] A satellite angle acquisition unit is used to obtain the altitude and azimuth angles of all visible satellites based on the satellite ephemeris file and the approximate coordinates of the user;
[0034] A rejection unit, used for rejecting low altitude angle satellites according to a preset cut-off altitude angle;
[0035] A single-difference integer ambiguity calculation unit, used for calculating the single-difference integer ambiguity by rounding to the nearest integer;
[0036] A baseline vector calculation unit, used for calculating the baseline vector using the integer ambiguity result;
[0037] The carrier heading angle acquisition unit is used to solve the carrier heading angle through a trigonometric function relationship.
[0038] Based on the same inventive concept, the present invention also proposes a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor runs the computer program stored in the memory, the processor executes a compact and low-cost GNSS direction finding method as described in any one of the above items.
[0039] Based on the same inventive concept, the present invention also proposes a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of a compact and low-cost GNSS direction finding method as described in any one of the above are executed.
[0040] The present invention is beneficial in that:
[0041] The traditional GNSS dual-antenna direction-finding method is limited in its use environment due to the limitation of its baseline length. In a compact and low-cost GNSS direction-finding method proposed in the present invention, an ultra-short baseline of 5 cm is constructed. Since it is less than 0.5 cycles, there is no need to use the LAMBDA algorithm with large computational complexity. At the same time, due to the relatively poor quality of low-cost antennas and unstable phase centers, the floating-point solution accuracy is low, and the use of the LAMBDA algorithm relies on the floating-point solution accuracy. Therefore, the present invention proposes to solve the integer ambiguity by the nearest integer method, which can greatly reduce the amount of calculation and improve the ambiguity fixation rate.
[0042] At the same time, the method described in the present invention also proposes the use of a receiver board that supports receiving dual antenna signals. Due to the common clock design of the two signals, the influence of the receiver clock error can be eliminated without inter-satellite difference, which can avoid the problem of replacing the reference star in the double difference process. Therefore, only single inter-station difference is required to eliminate the receiver clock error, satellite clock error, ionospheric delay, tropospheric delay, etc., and the entire solution process does not require low-precision pseudo-range observations. Unlike the solution of traditional RTK, the present invention has already solved the integer ambiguity in advance by the nearest integer method, so the equation is not rank-deficient, and the baseline vector can be obtained by using the least squares method, and then the heading angle is solved according to the trigonometric function relationship. It has important development potential in the direction-finding scenario application of low-cost, low-computing power, small-size platforms. BRIEF DESCRIPTION OF THE DRAWINGS
[0043] Figure 1 This is a flow chart of a compact and low-cost GNSS direction finding method according to implementation mode 1. DETAILED DESCRIPTION
[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.
[0045] Implementation method 1, see Figure 1 The present embodiment describes a compact and low-cost GNSS direction finding method, the method comprising:
[0046] Receive GNSS single-frequency ultra-short baseline carrier phase observations using a common clock dual-antenna board and ultra-short baseline;
[0047] Construct inter-station differences based on carrier phase observations of ultra-short baselines;
[0048] Obtain the altitude and azimuth angles of all visible satellites based on the satellite ephemeris file and the approximate coordinates of the user;
[0049] Eliminate low altitude angle satellites according to the preset cut-off altitude angle;
[0050] The single-difference integer ambiguity is calculated by rounding to the nearest integer;
[0051] Calculate the baseline vector using the integer ambiguity results;
[0052] The carrier heading angle is solved through trigonometric function relationship.
[0053] In a compact and low-cost GNSS direction-finding method proposed in this embodiment, precise measurements are performed by using an ultra-short baseline (i.e., a 5 cm baseline) in combination with a common-clock dual-antenna board. This allows relatively accurate measurement results to be obtained even when the baseline is very short. This overcomes the problem in traditional GNSS dual-antenna direction-finding technology that the measurement accuracy is usually proportional to the baseline length, and the longer the baseline, the higher the accuracy, thereby meeting the needs of small carriers.
[0054] At the same time, the co-clock dual-antenna board used in this embodiment means that on one board, the original observations of two antennas can be received, and the same receiver clock is used, so the clock errors of the two receivers are consistent. By optimizing the hardware design, the two antennas can share the same clock, thereby reducing the requirements for the baseline length between antennas, which is particularly suitable for scenes with narrow space. The compact and low-cost GNSS direction-finding method proposed in this embodiment can reduce the overall cost and adapt to smaller space requirements by using an ultra-short baseline and an optimized co-clock dual-antenna board, making it competitive in some applications that require space and cost.
[0055] In this embodiment, the satellites are screened according to their altitude angles to eliminate satellites with low altitude angles, ensuring that only satellites with good signal quality are used for positioning, thus avoiding interference from low-quality signals and improving measurement accuracy.
[0056] In GNSS direction finding, ambiguity refers to the integer cycle uncertainty in carrier phase measurement. Traditional methods usually require a longer baseline and LAMBDA algorithm to resolve ambiguity, while this implementation uses rounding to the nearest integer to calculate single-difference integer ambiguity, which can effectively handle ambiguity in the case of ultra-short baselines, solving the problem of difficulty in resolving ambiguity under short baseline conditions, thereby improving measurement accuracy.
[0057] Implementation method 2: This implementation method further limits the compact and low-cost GNSS direction finding method described in implementation method 1, wherein the length of the ultra-short baseline is less than 0.5 weeks.
[0058] In this implementation, an ultra-short baseline (less than 0.5 cycles) GNSS single-frequency carrier phase observation is used, and accurate positioning and direction finding are achieved by utilizing the phase difference of the ultra-short baseline. This means that even small space-constrained carriers can perform high-precision GNSS measurements, significantly reducing the requirements for hardware space and baseline length.
[0059] Implementation method 3: This implementation method further defines the compact and low-cost GNSS direction finding method described in implementation method 2. The method uses a common clock dual-antenna board to receive GNSS single-frequency ultra-short baseline carrier phase observations, including:
[0060] φi=ρ i +c(t-τi)-Ii+Ti+λNi+ε
[0061] Among them, φ is the carrier phase observation, ρ is the geometric distance, the superscript i is the satellite number, I is the ionospheric delay, T is the tropospheric delay, t is the receiver clock error, τ is the satellite clock error, N is the integer ambiguity, λ is the wavelength, and ε is the noise.
[0062] Embodiment 4: This embodiment further defines the compact and low-cost GNSS direction finding method described in Embodiment 3. The inter-station difference is constructed based on the carrier phase observation of the ultra-short baseline, including:
[0063]
[0064] Among them, the subscript r represents a mobile station, b represents a base station, and the subscript rb represents an inter-station single difference.
[0065] This embodiment is explained in conjunction with the third embodiment. In this embodiment, single-frequency GNSS and ultra-short baseline are used, and high-precision measurement can be achieved at low cost through carrier phase measurement. The common clock dual-antenna board configuration simplifies the hardware design and reduces system cost and complexity. Through dual-antenna differential technology, error sources such as ionosphere, troposphere, and clock errors can be eliminated to provide higher-precision measurement results.
[0066] Embodiment 5: This embodiment further limits the compact and low-cost GNSS direction finding method described in Embodiment 3, wherein the method of calculating the single-difference integer ambiguity by rounding to the nearest integer includes:
[0067]
[0068] Among them, [] indicates rounding.
[0069] In GNSS phase differential, ambiguity resolution is often a complex and computationally intensive process. Traditional methods require a long baseline for ambiguity resolution. In this implementation, the calculation process of single-difference integer ambiguity is simplified by rounding to the nearest integer. This method not only improves computational efficiency, but also can obtain more accurate ambiguity solutions in the case of short baselines, further improving accuracy and practicality.
[0070] Embodiment 6: This embodiment further limits the compact and low-cost GNSS direction finding method described in Embodiment 3. The method of calculating the baseline vector using the integer ambiguity result includes:
[0071]
[0072] [ΔxΔyΔz]T =(G T G) -1 G T b
[0073] The Jacobian matrix G is only related to the geometric position of the satellite position relative to the user, so it is usually called the geometric matrix, [ΔxΔyΔz] T is the baseline vector.
[0074] Embodiment 7: This embodiment further limits the compact and low-cost GNSS direction finding method described in Embodiment 1. The method of solving the carrier heading angle by trigonometric function relationship includes:
[0075]
[0076] Among them, α is the heading angle, Δe is the projection of the baseline vector in the east direction, and Δn is the projection of the baseline vector in the north direction.
[0077] This embodiment is explained in conjunction with the sixth embodiment. Traditional baseline vector calculation requires a longer baseline and more satellite data, and it is difficult to obtain an accurate baseline vector in the case of a shorter baseline. In this embodiment, by accurately solving the integer ambiguity results, the baseline vector can be accurately calculated, and the heading angle of the carrier can be further solved based on the trigonometric function relationship. This method not only simplifies the calculation process, but also can achieve high-precision heading angle measurement under shorter baseline conditions, and is particularly suitable for small carriers with limited space.
[0078] Embodiment 8: A compact and low-cost GNSS direction finding system according to this embodiment, the system comprises:
[0079] A carrier phase observation acquisition unit, used for receiving GNSS single-frequency ultra-short baseline carrier phase observations using a common clock dual-antenna board and an ultra-short baseline;
[0080] An inter-station difference construction unit, used for constructing inter-station differences based on carrier phase observations of ultra-short baselines;
[0081] A satellite angle acquisition unit is used to obtain the altitude and azimuth angles of all visible satellites based on the satellite ephemeris file and the approximate coordinates of the user;
[0082] A rejection unit, used for rejecting low altitude angle satellites according to a preset cut-off altitude angle;
[0083] A single-difference integer ambiguity calculation unit, used for calculating the single-difference integer ambiguity by rounding to the nearest integer;
[0084] A baseline vector calculation unit, used for calculating the baseline vector using the integer ambiguity result;
[0085] The carrier heading angle acquisition unit is used to solve the carrier heading angle through a trigonometric function relationship.
[0086] Embodiment 9. A computer device described in this embodiment includes a memory and a processor, wherein a computer program is stored in the memory. When the processor runs the computer program stored in the memory, the processor executes a compact and low-cost GNSS direction finding method described in any one of embodiments 1 to 7.
[0087] Embodiment 10. This embodiment provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of a compact and low-cost GNSS direction finding method as described in any one of embodiments 1 to 7 are executed.
[0088] Implementation 11: This implementation provides a specific example of a compact and low-cost GNSS direction finding method described in Implementation 1, and is also used to explain Implementation 2 to Implementation 7. Specifically:
[0089] A compact and low-cost GNSS direction finding method proposed in this embodiment is suitable for low-cost, low-computing power and small-size platforms, and can meet the heading requirements of drones, ships, vehicles, etc., including the following steps:
[0090] A common-clock dual-antenna board is used to receive GNSS single-frequency ultra-short baseline carrier phase observations. The troposphere and ionosphere can be eliminated through inter-station single difference, and the influence of the receiver clock error can be eliminated without inter-satellite difference. When the baseline length is less than 0.5 week, the LAMBDA method with large computational complexity can be avoided. The single-difference integer ambiguity can be solved by the nearest integer method, and finally the baseline vector can be calculated using the least squares method, thereby calculating the heading angle.
[0091] Specifically, taking a 5cm baseline as an example and using the dual-antenna BDStar UM982 dual-antenna common clock board, the specific execution steps are as follows:
[0092] (1) By using an ultra-short baseline and dual-antenna clock card and a low-cost computing platform to receive raw data, the carrier phase observation (unit: week) can be expressed as:
[0093] φi=ρ i +c(t-τi)-Ii+Ti+λNi+ε
[0094] Among them, φ is the carrier phase observation; ρ is the geometric distance; the superscript i is the satellite number; I and T represent the ionospheric delay and tropospheric delay, respectively; t and τ represent the receiver clock error and satellite clock error, respectively; N and λ represent the integer ambiguity and its wavelength, respectively; ε is the noise.
[0095] (2) Using the common clock dual-antenna board to receive GNSS ultra-short baseline carrier phase observations and construct inter-station differences, the receiver clock error, satellite clock error, ionospheric delay, tropospheric delay, etc. can be eliminated. The inter-station difference can be expressed as:
[0096]
[0097] Among them, φ is the carrier phase observation; ρ is the geometric distance; the superscript i is the satellite number; I and T represent the ionospheric delay and tropospheric delay, respectively; t and τ represent the receiver clock error and satellite clock error, respectively; N and λ represent the integer ambiguity and its wavelength, respectively; ε is the noise.
[0098] (3) Using the satellite ephemeris file and the user's approximate coordinates, the altitude and azimuth angles of all visible satellites are solved.
[0099] (4) Eliminate low-altitude satellites by using the cut-off angle set by the user. The cut-off angle is usually set to 10°-15°.
[0100] (5) When using a 5 cm baseline, since it is less than 0.5 cycles, the effect of the baseline length can be ignored by rounding the left and right sides of the above equation to the nearest integer, and the single-difference integer ambiguity can be directly calculated:
[0101]
[0102] (6) Bring back the integer ambiguity and calculate the baseline vector using the least squares method:
[0103]
[0104] [ΔxΔyΔz] T =(G T G) -1 G T b
[0105] The Jacobian matrix G is only related to the geometric position of the satellite position relative to the user, so it is usually called the geometric matrix, [ΔxΔyΔz] T is the baseline vector.
[0106] (7) Finally, the heading angle of the carrier is solved by the trigonometric function relationship:
[0107]
[0108] Among them, α is the heading angle, Δe is the projection of the baseline vector in the east direction, and Δn is the projection of the baseline vector in the north direction.
[0109] Those skilled in the art will appreciate that the embodiments of the present disclosure may be provided as methods, systems or computer program products. Therefore, the present disclosure may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present disclosure may take the form of a computer program product implemented 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.
[0110] The present disclosure is described with reference to flowcharts and / or block diagrams of methods, devices (systems) and computer program products according to embodiments of the present disclosure. It should be understood that each process and / or block in the flowchart and / or block diagram and the combination of processes and / or blocks in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.
[0111] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.
[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure rather than to limit its protection scope. Although the present disclosure has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present disclosure, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the disclosed claims to be approved.
Claims
1. A compact and low-cost GNSS direction finding method, characterized in that: The method comprises: Receive GNSS single-frequency ultra-short baseline carrier phase observations using a common clock dual-antenna board and ultra-short baseline; Construct inter-station differences based on carrier phase observations of ultra-short baselines; Obtain the altitude and azimuth angles of all visible satellites based on the satellite ephemeris file and the approximate coordinates of the user; Eliminate low altitude angle satellites according to the preset cut-off altitude angle; The single-difference integer ambiguity is calculated by rounding to the nearest integer; Calculate the baseline vector using the integer ambiguity results; The carrier heading angle is solved through trigonometric function relationship.
2. A compact and low-cost GNSS direction finding method according to claim 1, characterized in that: The ultra-short baseline length is less than 0.5 cycle.
3. A compact and low-cost GNSS direction finding method according to claim 2, characterized in that: The method of receiving GNSS single-frequency ultra-short baseline carrier phase observations by using a common clock dual-antenna board includes: φi=ρ i +c(t-τi)-Ii+Ti+λNi+ε Among them, φ is the carrier phase observation, ρ is the geometric distance, the superscript i is the satellite number, I is the ionospheric delay, T is the tropospheric delay, t is the receiver clock error, τ is the satellite clock error, N is the integer ambiguity, λ is the wavelength, and ε is the noise.
4. A compact and low-cost GNSS direction finding method according to claim 3, characterized in that: The step of constructing inter-station differences based on the carrier phase observation of the ultra-short baseline includes: Among them, the subscript r represents a mobile station, b represents a base station, and the subscript rb represents an inter-station single difference.
5. A compact and low-cost GNSS direction finding method according to claim 3, characterized in that: The method of calculating the single-difference integer ambiguity by rounding to the nearest integer comprises: Among them, [] indicates rounding.
6. A compact and low-cost GNSS direction finding method according to claim 3, characterized in that: The method of calculating the baseline vector using the integer ambiguity result includes: [ΔxΔyΔz] T =(G T G) -1 G T b Where G is the Jacobian matrix, [ΔxΔyΔz] T is the baseline vector.
7. A compact and low-cost GNSS direction finding method according to claim 1, characterized in that: The method of solving the heading angle of the carrier by using the trigonometric function relationship includes: Among them, α is the heading angle, Δe is the projection of the baseline vector in the east direction, and Δn is the projection of the baseline vector in the north direction.
8. A compact and low-cost GNSS direction finding system, characterized in that: The system comprises: A carrier phase observation acquisition unit, used for receiving GNSS single-frequency ultra-short baseline carrier phase observations using a common clock dual-antenna board and an ultra-short baseline; An inter-station difference construction unit, used for constructing inter-station differences based on carrier phase observations of ultra-short baselines; A satellite angle acquisition unit is used to obtain the altitude and azimuth angles of all visible satellites based on the satellite ephemeris file and the approximate coordinates of the user; A rejection unit, used for rejecting low altitude angle satellites according to a preset cut-off altitude angle; A single-difference integer ambiguity calculation unit, used for calculating the single-difference integer ambiguity by rounding to the nearest integer; A baseline vector calculation unit, used for calculating the baseline vector using the integer ambiguity result; The carrier heading angle acquisition unit is used to solve the carrier heading angle through a trigonometric function relationship.
9. A computer device, characterized in that: The method comprises a memory and a processor, wherein a computer program is stored in the memory, and when the processor runs the computer program stored in the memory, the processor executes a compact and low-cost GNSS direction finding method according to any one of claims 1 to 7.
10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of a compact and low-cost GNSS direction finding method according to any one of claims 1 to 7 are executed.