A single-satellite positioning method combining wide and narrow beams

Abstract

The present invention discloses a single-satellite positioning method combining wide and narrow beams, which belongs to the field of satellite navigation and positioning. In view of the constraint that single-satellite positioning can obtain limited position information, the present invention constructs a single-satellite positioning strategy combining wide and narrow beams. In the wide beam stage, the satellite transmits a broadcast signal to cover the entire positioning area, and locks the potential position point of the terminal by processing the leading sequence signal fed back by the terminal. In the narrow beam stage, the coverage area is divided into multiple quadrants and narrow beams are transmitted in sequence. The quadrant in which the terminal is located is determined by measuring the received signal strength of the leading sequence signal fed back by each beam, eliminating the ambiguity of the position point locked in the wide beam stage to determine the specific position of the terminal, and realizing accurate positioning of the terminal under the working condition that single-satellite positioning can obtain limited information. The present invention improves the utilization efficiency of positioning parameters based on the single-satellite positioning strategy combining wide and narrow beams, realizes accurate positioning based on a single satellite, simplifies the positioning parameter solution, and reduces overhead and cost compared to multi-satellite positioning.

Description

Technical Field

[0001] The invention relates to a single-satellite positioning method based on the combination of wide and narrow beams, and belongs to the field of satellite navigation and positioning. Technical Background

[0002] With the continuous advancement of technology, people's demand for positioning and communication is also increasing. The emergence of the Global Navigation Satellite System (GNSS) and fifth-generation mobile communication technology (5G NR) has greatly met these needs. GNSS uses satellite positioning technology to provide reliable positioning and navigation services worldwide; 5G NR provides higher-speed, higher-capacity, and more reliable wireless communication technology. These technologies have been widely used in aviation, navigation, automotive, logistics, security and other fields, bringing great convenience to people's production and life.

[0003] Existing GNSS and 5G NR positioning technologies mostly utilize multi-platform positioning. This technology utilizes multiple satellites or base station platforms to transmit reference signals. The receiver processes and analyzes the signals, integrating the distance and delay information derived from these multiple signals to calculate the target's location. However, traditional multi-satellite positioning technology has limitations. The reception and processing of multiple signals are susceptible to interference and multipath effects, which can affect positioning accuracy and robustness. Furthermore, multi-satellite positioning requires processing multiple satellite signals, which incurs significant cost and overhead. In contrast, single-satellite positioning technology offers lower complexity and cost, while also offering greater robustness and reliability. Therefore, utilizing a single satellite for positioning has become a worthy research topic.

[0004] However, using traditional beamforming and signaling processes, the positioning information obtained by a single satellite is extremely limited. It can only determine information such as the distance between the satellite and the terminal. This leads to ambiguity in the distance points, making it difficult to accurately locate the terminal. Therefore, how to design an appropriate signaling process or signal format to maximize the amount of information obtained by single-satellite positioning to achieve efficient terminal positioning is an urgent problem to be solved. Summary of the Invention

[0005] In order to solve the problem of limited information acquisition and difficulty in achieving precise positioning in single-satellite positioning, the main purpose of the present invention is to provide a single-satellite positioning method combining wide and narrow beams. The method adopts a strategy of combining wide and narrow beams for single-satellite positioning. In the wide beam stage, the satellite transmits a broadcast signal to cover the entire positioning area. The potential location point of the terminal is locked by processing the preamble sequence signal fed back by the terminal. In the narrow beam stage, the coverage area is divided into multiple quadrants and narrow beams are transmitted sequentially. The quadrant in which the terminal is located is determined by measuring the received signal strength of the preamble sequence signal fed back by each beam. The ambiguity of the location point locked in the wide beam stage is eliminated to determine the specific location of the terminal, thereby achieving precise positioning of the terminal under conditions where single-satellite positioning obtains limited information. The present invention can improve the utilization efficiency of positioning parameters, achieve precise positioning based on a single satellite, simplify positioning parameter calculation, and reduce overhead and cost compared to multi-satellite positioning.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] The present invention discloses a single-satellite positioning method combining wide and narrow beams, comprising the following steps:

[0008] Step 1: To address the limitation of single-satellite positioning in obtaining position information, a single-satellite positioning strategy combining wide and narrow beams is constructed. In the wide beam stage, the delay and Doppler information are comprehensively utilized to improve the efficiency of positioning parameter utilization. By processing the narrow beam signal, the regional range information of the terminal is increased, thereby increasing the amount of terminal position information obtained and improving the efficiency of positioning parameter utilization.

[0009] Step 2: During the wide-beam phase, the satellite transmits a broadcast signal to the coverage area, covering the entire positioning area. The broadcast signal contains a preamble sequence signal used for access and positioning. Upon receiving the broadcast signal, the terminal in the area immediately feeds back a signal containing the preamble sequence to the satellite. After receiving the feedback signal, the satellite uses the autocorrelation characteristics of the pseudo-random sequence in the preamble sequence to calculate the distance between the terminal and the satellite, and estimates the Doppler frequency shift of the preamble sequence to obtain the angle of arrival of the signal. Combining these parameters, the two potential location points of the terminal are locked, achieving coarse positioning of the terminal.

[0010] Step 2.1 The satellite transmits a broadcast signal to the coverage area through a wide beam. The broadcast signal contains a preamble signal for access and positioning. The positioning reference signal in the preamble sequence uses the following sequence:

[0011]

[0012] Where c(i) is a pseudo-random sequence with good autocorrelation characteristics, and the initial value of the sequence is:

[0013]

[0014] Among them, n ID,seq ∈{0,1,2,...,4095} is the ID of this sequence, which is assigned by the satellite end. is the number of time slots, is the number of symbols in each time slot, and l is the index of the symbol.

[0015] After receiving the broadcast signal from the satellite, the terminal in step 2.2 immediately feeds back a signal with the preamble sequence p(m) to the satellite. After receiving the feedback signal, the satellite performs autocorrelation processing on the feedback signal and the locally generated sequence p(m) to calculate the transmission delay τ of the signal from the terminal to the satellite. Based on the delay, the distance R between the terminal and the satellite is determined:

[0016] R=τ×c0

[0017] Where c0 is the speed of light. Then, we determine the distance circle with the projection point from the satellite to the ground as the center and r as the radius. The terminal is located on this distance circle. The radius r of the distance circle is:

[0018]

[0019] Where h is the height of the satellite from the ground.

[0020] Step 2.3 The satellite performs Doppler estimation on the received feedback signal. Compared with the satellite's operating speed, the terminal's movement speed is negligible, so only the satellite's operating speed is considered when performing Doppler estimation. The Doppler frequency shift caused by satellite operation is f d , then the received signal at the satellite end is expressed as

[0021]

[0022] Among them, f c is the carrier center frequency, and T is the time interval between the leading sequence points. The satellite uses the FFT algorithm to estimate the Doppler frequency shift f of the signal. d ,get

[0023]

[0024] Where M is the total number of symbols in the leading sequence. Find the l value index corresponding to the peak value of a(l) as l0, satisfying f d T-l0 / M=0, so the estimated value of Doppler shift is

[0025] f d =l0 / MT

[0026] Let the arrival angle of the satellite receiving signal be θ, and the Doppler frequency shift and the satellite's speed v satisfy the following relationship:

[0027] f d=vf c cosθ / c0

[0028] Therefore, the arrival angle of the received signal is calculated based on the Doppler frequency shift estimate:

[0029] θ=arccos(f d c0 / vf c )

[0030] Then, two potential terminal position points a and b on the distance circle are locked. The terminal position points a and b are distributed on both sides of the satellite's movement direction and are axially symmetric about the satellite's movement direction. The two potential position points of the terminal are locked through the feedback leading sequence signal to achieve coarse positioning of the terminal.

[0031] Step 3: Building on the coarse positioning of the terminal achieved in Step 2, the satellite first divides its coverage area into four quadrants and sequentially transmits a broadcast signal to each quadrant using a narrow beam. Upon receiving the broadcast signal, the terminal immediately transmits a feedback signal back to the satellite. The satellite determines the quadrant in which the terminal is located by measuring the received signal strength of the pilot sequence fed back by each beam. This deambiguates the position point determined in the wide-beam phase to eliminate erroneous position estimates obtained during the wide-beam phase, achieving precise single-satellite positioning of the terminal.

[0032] In step 3.1, the satellite divides the ground coverage area into four equal quadrants, using its own direction of travel as the coordinate axis. The terminal's two potential locations, a and b, are located in two quadrants, symmetrically along the satellite's direction of travel. The satellite transmits a broadcast signal with a preamble sequence, p(m), to each of the four quadrants using four narrow beams. After receiving the broadcast signal, the terminal transmits a feedback signal to the satellite. The format of the satellite feedback signal is the same as that in step 2.

[0033] In step 3.2, after receiving the feedback signal from the narrow beam, the satellite measures the received signal strength (RSS) of the leading sequence in each narrow beam and locks the quadrant corresponding to the narrow beam with the largest RSS, which is determined as the area where the terminal is located. This eliminates the ambiguity of the two roughly estimated position points a and b, determines the final position point a of the terminal, eliminates the erroneous position estimate obtained in the wide beam stage, and achieves precise single-satellite positioning of the terminal.

[0034] Beneficial effects:

[0035] 1. The single-satellite positioning method based on a combination of wide and narrow beams disclosed in this invention addresses the limitations of single-satellite positioning, which hinders accurate position estimation due to limited information acquisition. By using a wide-beam pseudo-random sequence to acquire terminal distance, angle, and other information, the method locks onto the terminal's potential location for coarse positioning. Furthermore, using a narrow-beam pseudo-random sequence to acquire information about the terminal's area, the method deblurs the potential location for coarse positioning, eliminates erroneous position estimates obtained during the wide-beam phase, and achieves precise position estimation, improving the utilization efficiency of positioning parameters. Compared to multi-satellite positioning, this method reduces the complexity of positioning information calculation, saving the overhead and cost of terminal positioning.

[0036] 2. The single-satellite positioning method based on the combination of wide and narrow beams disclosed in the present invention transmits broadcast signals to the entire covered area through the satellite wide beam in the coarse positioning stage, and uses the good autocorrelation characteristics of the pseudo-random sequence in the broadcast signal to achieve accurate measurement of terminal distance, Doppler, arrival angle and other information, thereby determining the two potential position points of the terminal. In traditional positioning methods, the ranging of a single link can only determine the distance circle, the positioning range is not focused, and the angle measurement needs to be completed with the help of multiple antennas at the receiving end. Compared with traditional positioning methods, the present invention uses Doppler estimation to calculate angle information, combines distance information to lock the potential position point of the terminal, improves the utilization efficiency of positioning parameters, and makes the positioning range more focused.

[0037] 3. The single-satellite positioning method based on the combination of wide and narrow beams disclosed in the present invention, in the precise positioning stage, on the basis of achieving coarse positioning of the terminal in the wide beam stage, divides the coverage area into multiple quadrants and transmits narrow beams in sequence. The quadrant in which the terminal is located is determined by measuring the received signal strength of the leading sequence in each narrow beam feedback signal, and the regional information of the terminal position is added. The position point determined in the wide beam stage is deblurred, and the erroneous position estimate obtained in the wide beam stage is eliminated, thereby achieving precise positioning of the terminal under conditions where the information obtained by single-satellite positioning is limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Positioning scene graph for satellite navigation;

[0039] Figure 2 This is a flow chart of the single-satellite positioning method based on the combination of wide and narrow beams disclosed in the present invention;

[0040] Figure 3 This is a schematic diagram of low-orbit satellite coverage;

[0041] Figure 4 Schematic diagram of the range circle determined for the wide beam;

[0042] Figure 5 is a schematic diagram of the feedback signal arrival angle;

[0043] Figure 6Schematic diagram of potential terminal locations determined by angle of arrival;

[0044] Figure 7 Schematic diagram of determining the specific location of the terminal for narrow beam. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to have a deeper understanding of the implementation ideas of the solutions of the present invention, the technical solutions in the embodiments of the present invention will be described in detail and clearly in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementation cases obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention. The specific steps of the embodiments of the present invention will be described below in conjunction with specific scenarios.

[0046] Example:

[0047] The satellite navigation positioning scenario of this embodiment is as follows Figure 1 As shown, traditional positioning methods generally require 3-4 satellites to determine the location of the terminal. The present invention considers positioning based on a single low-orbit satellite at an altitude of 1000km from the ground. The single-satellite positioning process is divided into two stages. In the wide-beam stage, the satellite generates and transmits a broadcast signal containing a positioning preamble sequence. The terminal to be positioned on the ground receives the broadcast signal and transmits a feedback signal to the satellite. The satellite platform uses the feedback signal to calculate the time delay and Doppler frequency shift, determine the distance circle where the terminal is located, and lock the two potential position points of the terminal; in the narrow-beam stage, the satellite divides the coverage area into four quadrants and sends a broadcast signal to each of the four quadrants through four narrow beams. After receiving the signal, the terminal sends a feedback signal. The satellite determines the quadrant where the terminal is located by measuring the received signal strength of the feedback signal in each narrow beam, eliminating the position point ambiguity problem existing in the wide-beam stage, and finally obtaining the specific position of the terminal.

[0048] like Figure 2 As shown, the single-satellite positioning method based on the combination of wide and narrow beams disclosed in this embodiment is divided into a wide beam stage and a narrow beam stage, and the specific implementation steps are as follows:

[0049] Step 1: To address the limited position information obtained by single-satellite positioning, a strategy combining wide and narrow beams is adopted to increase the amount of terminal position information obtained, improve the efficiency of positioning parameter utilization, and ultimately achieve precise positioning of the terminal. First, the satellite uses a wide beam to cover the entire service area. By processing the pseudo-random sequence obtained from the feedback within the wide beam, positioning information such as the distance between the satellite terminals and the arrival angle is obtained, and the potential location point of the terminal is locked for coarse positioning. Then, a narrow beam is used to cover each sub-area separately. By processing the pseudo-random sequence fed back in the narrow beam, the received signal strength is obtained. The potential location points obtained from the coarse positioning are deblurred, eliminating the erroneous estimated position obtained in the wide beam stage, and obtaining the final accurate position estimate of the terminal. In short, this step adopts a strategy of combining wide and narrow beams for single-satellite positioning. In the wide beam stage, information such as delay and Doppler is comprehensively utilized to improve the efficiency of positioning parameter utilization. By processing the narrow beam signal to increase the area where the terminal is located, the above information is finally determined to accurately determine the terminal's position, achieving single-satellite positioning.

[0050] Step 2: During the wide-beam phase, the satellite transmits a broadcast signal to the coverage area, covering the entire positioning area. The broadcast signal contains a preamble sequence signal used for access and positioning. Upon receiving the broadcast signal, the terminal in the area immediately feeds back a signal containing the preamble sequence to the satellite. After receiving the feedback signal, the satellite uses the autocorrelation characteristics of the pseudo-random sequence in the preamble sequence to calculate the distance between the terminal and the satellite, and estimates the Doppler frequency shift of the preamble sequence to obtain the angle of arrival of the signal. Combining these parameters, the two potential location points of the terminal are locked, achieving coarse positioning of the terminal.

[0051] Step 2.1 The satellite transmits the broadcast signal to the coverage area through a wide beam, such as Figure 3 The broadcast signal contains a preamble signal used for access and positioning. The positioning reference signal in the preamble sequence uses the following sequence:

[0052]

[0053] Where c(i) is a pseudo-random sequence with good autocorrelation characteristics, and the initial value of the sequence is:

[0054]

[0055] Among them, n ID,seq ∈{0,1,2,...,4095} is the ID of this sequence, which is assigned by the satellite end. is the number of time slots, is the number of symbols in each time slot, and l is the index of the symbol.

[0056] In the embodiment, the orbit altitude of the satellite is h=1000 km, the coverage radius is r0=50 km, the bandwidth occupied by the broadcast signal is B=200 MHz, and the beam width is α=5.7°.

[0057] After receiving the broadcast signal from the satellite, the terminal in step 2.2 immediately feeds back a signal with the preamble sequence p(m) to the satellite. After receiving the feedback signal, the satellite performs autocorrelation processing on the feedback signal and the locally generated sequence p(m) to calculate the transmission delay τ of the signal from the terminal to the satellite. Based on the delay, the distance R between the terminal and the satellite is determined:

[0058] R=τ×c0

[0059] Where c0 is the speed of light. Then determine the distance circle with the projection point from the satellite to the ground as the center and r as the radius. The terminal is located on this distance circle, such as Figure 4 As shown. The radius r from the circumference is:

[0060]

[0061] Where h is the height of the satellite from the ground.

[0062] Step 2.3 The satellite performs Doppler estimation on the received feedback signal. Compared with the satellite's speed, the terminal's speed is negligible, so only the satellite's speed is considered when performing Doppler estimation. Assume that the Doppler frequency shift caused by the satellite's movement is f d , then the received signal at the satellite end can be expressed as

[0063]

[0064] Among them, f c is the carrier center frequency, and T is the time interval between the leading sequence points. The satellite uses the FFT algorithm to estimate the Doppler frequency shift f of the signal. d ,get

[0065]

[0066] Where M is the total number of symbols in the leading sequence. Find the l value index corresponding to the peak value of a(l) as l0, satisfying f d T-l0 / M=0, so the estimated value of Doppler shift is

[0067] f d =l0 / MT

[0068] like Figure 5 As shown, let the arrival angle of the satellite receiving signal be θ, and the Doppler frequency shift and the satellite's running speed v satisfy the following relationship

[0069] f d=vf c cosθ / c0

[0070] Therefore, the arrival angle of the received signal can be calculated based on the Doppler frequency shift estimate:

[0071] θ=arccos(f d c0 / vf c )

[0072] Then, two potential terminal position points a and b on the distance circle are locked. The terminal position points a and b are distributed on both sides of the satellite's running direction and are axisymmetric with respect to the satellite's running direction, such as Figure 6 This step uses the feedback of the leading sequence signal to lock the two potential location points of the terminal, thus achieving coarse positioning of the terminal.

[0073] Step 3: Building on the coarse positioning of the terminal achieved in Step 2, the satellite first divides its coverage area into four quadrants and broadcasts a signal to each quadrant sequentially using a narrow beam. Upon receiving the broadcast signal, the terminal immediately transmits a feedback signal back to the satellite. The satellite determines the quadrant in which the terminal is located by measuring the received signal strength of the preamble sequence fed back by each beam. This deambiguates the position point determined in the wide-beam phase to eliminate erroneous position estimates obtained during the wide-beam phase, ultimately achieving precise positioning of the terminal.

[0074] Step 3.1 The satellite uses its own running direction as the coordinate axis to divide the ground coverage area into four quadrants. At this time, the two potential location points a and b of the terminal are located in two quadrants respectively and are symmetrical along the satellite running direction. Figure 7 As shown, the satellite transmits a broadcast signal with a preamble sequence p(m) to four quadrants in turn through four narrow beams. After receiving the broadcast signal, the terminal transmits a feedback signal to the satellite. The format of the satellite feedback signal is the same as the signal format in step 2.

[0075] Step 3.2 After receiving the feedback signal from the narrow beam, the satellite measures the received signal strength RSS of the pilot sequence in each narrow beam and locks the quadrant corresponding to the narrow beam with the largest RSS, which is determined as the area where the terminal is located, thereby eliminating the ambiguity of the two roughly estimated position points a and b and locking the final position point a of the terminal, as shown in Figure 7 As shown, the erroneous position estimation obtained in the wide beam stage is eliminated to achieve the final determination of the terminal position.

[0076] The above specific description further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. 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-satellite positioning method combining wide and narrow beams, characterized by: The following steps are included: Step 1: To address the limited position information obtained by single-satellite positioning, a single-satellite positioning strategy that combines wide and narrow beams is constructed. In the wide beam phase, delay and Doppler information are comprehensively utilized to improve the efficiency of positioning parameter utilization. By processing narrow beam signals, the area range information of the terminal is increased, thereby increasing the amount of terminal position information obtained and improving the efficiency of positioning parameter utilization. Step 2: During the wide-beam phase, the satellite transmits a broadcast signal to the coverage area, ensuring that the satellite signal covers the entire positioning area. The broadcast signal contains a preamble sequence signal used for access and positioning. Upon receiving the broadcast signal, the terminal in the area immediately feeds back a signal containing the preamble sequence to the satellite. After receiving the feedback signal, the satellite uses the autocorrelation characteristics of the pseudo-random sequence in the preamble sequence to calculate the distance between the terminal and the satellite, and estimates the Doppler shift of the preamble sequence to obtain the angle of arrival of the signal. Combining these parameters, the two potential locations of the terminal are locked, achieving coarse positioning of the terminal. Step 3: Based on the coarse positioning of the terminal achieved in Step 2, the satellite first divides the coverage area into four quadrants and transmits a broadcast signal to each quadrant in turn using a narrow beam. After receiving the broadcast signal, the terminal immediately transmits a feedback signal to the satellite. The satellite determines the quadrant where the terminal is located by measuring the received signal strength of the leading sequence fed back by each beam, deambiguates the position point determined in the wide beam stage, and eliminates the erroneous position estimate obtained in the wide beam stage, thereby achieving precise single-satellite positioning of the terminal.

2. The single-satellite positioning method using a combination of wide and narrow beams according to claim 1, wherein: The implementation method of step 2 is: Step 2.1 The satellite transmits a broadcast signal to the coverage area through a wide beam. The broadcast signal contains a preamble sequence signal used for access and positioning. The positioning reference signal in the preamble sequence uses the following sequence: Where c(i) is a pseudo-random sequence with good autocorrelation characteristics, and the initial value of the sequence is: Among them, n ID,seq ∈{0,1,2,...,4095} is the ID of this sequence, which is assigned by the satellite end. is the number of time slots, is the number of symbols in each time slot, l is the index of the symbol; After receiving the broadcast signal from the satellite, the terminal in step 2.2 immediately feeds back a signal with the preamble sequence p(m) to the satellite. After receiving the feedback signal, the satellite performs autocorrelation processing on the feedback signal and the locally generated sequence p(m) to calculate the transmission delay τ of the signal from the terminal to the satellite. Based on the delay, the distance R between the terminal and the satellite is determined: R=τ×c0 Where c0 is the speed of light. Then, we determine the distance circle with the projection point from the satellite to the ground as the center and r as the radius. The terminal is located on this distance circle. The radius r of the distance circle is: Where h is the height of the satellite from the ground; Step 2.3 The satellite performs Doppler estimation on the received feedback signal. When performing Doppler estimation, only the satellite speed is considered. The Doppler frequency shift caused by the satellite movement is f d , then the received signal at the satellite end is expressed as Among them, f c is the carrier center frequency, T is the time interval between the leading sequence points; the satellite uses the FFT algorithm to estimate the Doppler frequency shift f of the signal d ,get Where M is the total number of symbols in the leading sequence; the l value index corresponding to the peak value of the amplitude of a(l) is l0, satisfying f d T-l0 / M=0, so the estimated value of Doppler shift is f d =l0 / MT Let the arrival angle of the satellite receiving signal be θ, and the Doppler frequency shift and the satellite's speed v satisfy the following relationship: f d =vf c cosθ / c0 Therefore, the arrival angle of the received signal is calculated based on the Doppler frequency shift estimate: θ=arccos(f d c0 / vf c ) Then, two potential terminal position points a and b on the distance circle are locked. The terminal position points a and b are distributed on both sides of the satellite's movement direction and are axially symmetric about the satellite's movement direction. The two potential position points of the terminal are locked through the feedback leading sequence signal to achieve coarse positioning of the terminal.

3. The single-satellite positioning method using a combination of wide and narrow beams according to claim 2, wherein: The implementation method of step three is: Step 3.1: The satellite divides the ground coverage area into four equal quadrants, using its own direction of travel as the coordinate axis. The terminal's two potential locations, a and b, are located in two quadrants, respectively, and are symmetrical about the satellite's direction of travel. The satellite transmits a broadcast signal with a preamble sequence, p(m), to each of the four quadrants using four narrow beams. After receiving the broadcast signal, the terminal transmits a feedback signal to the satellite. The format of the satellite feedback signal is the same as that in step 2. In step 3.2, after receiving the feedback signal from the narrow beam, the satellite measures the received signal strength (RSS) of the leading sequence in each narrow beam and locks the quadrant corresponding to the narrow beam with the largest RSS, which is determined as the area where the terminal is located. This eliminates the ambiguity of the two roughly estimated position points a and b, determines the final position point a of the terminal, eliminates the erroneous position estimate obtained in the wide beam stage, and achieves precise single-satellite positioning of the terminal.

Images