Satellite selection method based on multi-beam receiving antenna

Abstract

The embodiment of the invention discloses a satellite selection method based on a multi-beam receiving antenna. The method comprises the following steps: determining spatial positions of N visible satellites according to a navigation satellite ephemeris; transmitting M receiving beams by using a multi-beam receiving antenna and uniformly dividing the space into M areas; classifying satellites with elevation angles greater than or equal to a first threshold value and carrier-to-noise ratios greater than or equal to a second threshold value in each area into a first candidate satellite set; calculating the comprehensive quality score of each satellite in each first candidate satellite set according to the elevation angle of the satellite, the carrier-to-noise ratio of the satellite and the average spherical angular distance of the satellite in the scanning beam angle; descending the comprehensive quality score of each satellite in each first candidate satellite set, and reserving W satellites corresponding to the first W comprehensive quality scores to obtain M second candidate satellite sets; l satellites are selected from the M second candidate satellite sets, precision factors of the L satellites are calculated, and the L satellites corresponding to the minimum value of the precision factors of the L satellites are selected as final satellite selection results.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of global navigation satellite system receiving technology. More particularly, it relates to a satellite selection method based on a multi-beam receiving antenna. BACKGROUND

[0002] Traditional global navigation satellite system (GNSS) receivers receive all visible satellite signals simultaneously through an omnidirectional antenna, and then perform "satellite selection" in the baseband to reduce the computational load and improve positioning accuracy. However, in urban canyons, forested areas, or multipath environments, an omnidirectional antenna will introduce a large number of low-quality signals. In recent years, multi-beam arrays or beamforming antennas have been used for spatial filtering, but existing technologies only use beams for "signal enhancement" or "interference suppression", and do not fully utilize the priori geometric information of "multi-beam partitioning" for global dilution of precision (DOP) optimization.

[0003] Therefore, there is an urgent need for a method that, under the architecture of a beam antenna with M1 limited regions, quickly selects N1 high-quality satellites (N1≤M1) so that the DOP value corresponding to the final geometric configuration is optimal, thereby improving positioning accuracy and robustness. SUMMARY

[0004] The purpose of the present application is to provide a satellite selection method based on a multi-beam receiving antenna to solve at least one of the problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The first aspect of the present application provides a satellite selection method based on a multi-beam receiving antenna, the method comprising:

[0007] acquiring a navigation satellite ephemeris using an omnidirectional receiving antenna, determining the spatial positions of N visible satellites according to the navigation satellite ephemeris, N being a positive integer;

[0008] emitting M receiving beams using the multi-beam receiving antenna and dividing the space uniformly into M regions, each receiving beam having a scanning beam angle, the M scanning beam angles of the M receiving beams being mutually non-overlapping, M being a positive integer;

[0009] grouping satellites with an elevation angle greater than or equal to a first threshold value and a carrier-to-noise ratio greater than or equal to a second threshold value in each region into a first candidate satellite set, obtaining M first candidate satellite sets;

[0010] calculating a comprehensive quality score of each satellite in each first candidate satellite set according to the satellite's elevation angle, the satellite's carrier-to-noise ratio, and the average spherical angular distance of the satellite within the scanning beam angle, obtaining the comprehensive quality score of each satellite in the M first candidate satellite sets;

[0011] The comprehensive quality scores of each satellite in each first candidate satellite set are ranked in descending order, and W satellites corresponding to the top W comprehensive quality scores are reserved to obtain M second candidate satellite sets, W being a positive integer;

[0012] L satellites are selected from the M second candidate satellite sets, and precision factors of the L satellites are calculated, and L satellites corresponding to the minimum value of the precision factors of the L satellites are selected as the final satellite selection result, L being a positive integer.

[0013] Optionally, the determining the spatial positions of the N visible satellites according to the navigation satellite ephemeris comprises:

[0014] The unit direction vectors of the N visible satellites in the station-centered coordinate system are calculated based on the position of the omnidirectional receiving antenna.

[0015] Optionally, the first threshold value ranges from 10° to 20°.

[0016] The second threshold value ranges from 30 dBHz to 40 dBHz.

[0017] Optionally, the comprehensive quality score of each satellite in each first candidate satellite set is calculated according to the elevation angle of the satellite, the carrier-to-noise ratio of the satellite, and the average spherical angular distance of the satellite within the scanning beam angle, and comprises:

[0018] Score(S)=w1·CN0(S)+w2·El(S)+w3·Dist(S,Ω j )

[0019] In the formula, Score(S) is the comprehensive quality score of the Sth satellite in the first candidate satellite set; w1 is the first weight coefficient, w2 is the second weight coefficient, w3 is the third weight coefficient, and 1=w1+w2+w3; CN0(S) is the elevation angle of the unit direction vector of the Sth satellite; El(S) is the carrier-to-noise ratio of the unit direction vector of the Sth satellite; Dist(S,Ω j ) is the average spherical angular distance of the satellite S within the scanning beam angle Ω j of the jth receiving beam, j∈M.

[0020] Optionally, the calculation formula of the average spherical angular distance of the satellite S within the scanning beam angle Ω j of the jth receiving beam is:

[0021]

[0022] In the formula, ∑() is a summation function; k is the number of satellites within the scanning beam angle Ω j , k being a positive integer; arccos() is an inverse cosine function; v iis a unit direction vector of the i-th satellite in the first candidate satellite set; v s is a unit direction vector of the S-th satellite in the first candidate satellite set.

[0023] Optionally, the selecting L satellites from the M second candidate satellite sets and calculating the precision factors of the L satellites comprises:

[0024] calculating an enumeration scale, the calculation formula of the enumeration scale being:

[0025] Y=M·k

[0026] In the formula, Y is the enumeration scale;

[0027] judging whether the enumeration scale is less than or equal to a third threshold value, if yes, using an exhaustive method to calculate the precision factors of the L satellites;

[0028] if no, using a greedy iteration method to calculate the precision factors of the L satellites.

[0029] Optionally, the method further comprises:

[0030] if the unit direction vector of any one of the N visible satellites is not in the corresponding area, updating the number of visible satellites and recalculating the final satellite selection result.

[0031] Optionally, the method further comprises:

[0032] if the final satellite selection result is obtained and the unit direction vector of any one of the N visible satellites is in the corresponding area when the N visible satellites move in a preset period, calculating and determining the final satellite selection result.

[0033] Optionally, the precision factor comprises a geometric precision factor, a spatial position precision factor, a horizontal position precision factor or an elevation precision factor.

[0034] Optionally, the multi-beam receiving antenna comprises a parabolic antenna, a patch array antenna, a phased array antenna or a dielectric lens antenna.

[0035] The present application has the following advantages:

[0036] The technical scheme of the present application solves the problems of introducing a large number of low-quality signals by an omnidirectional antenna in a complex environment, thereby affecting signal quality and reducing positioning accuracy, and effectively improves the quality of signals received by the multi-beam receiving antenna; the satellite selection method with minimized precision factor supports periodic dynamic update, can quickly select the optimal satellite combination, is suitable for complex environments such as vehicle-mounted and airborne, and significantly improves positioning accuracy and robustness. BRIEF DESCRIPTION OF DRAWINGS

[0037] The specific embodiments of the present application will be further described in details below with reference to the accompanying drawings.

[0038] Figure 1 A flow chart of the method for selecting satellites based on a multi-beam receiving antenna is shown. DETAILED DESCRIPTION

[0039] In order to more clearly illustrate the present application, the present application will be further described in details below with reference to the embodiments and the accompanying drawings. Like components are denoted by the same reference numerals in the drawings. It should be understood by those skilled in the art that the specific description below is illustrative rather than limiting, and should not limit the scope of protection of the present application.

[0040] A conventional global navigation satellite system (GNSS) receiver receives all visible satellite signals through an omnidirectional antenna at the same time, and then performs "selecting satellites" in the baseband to reduce the operation load and improve the positioning accuracy. However, in the urban canyon, forest or multipath environment, the omnidirectional antenna will introduce a large number of low-quality signals. In recent years, multi-beam arrays or beamforming antennas are used for spatial filtering, but the prior art only uses the beam for "signal enhancement" or "interference suppression", and does not fully utilize the priori geometric information of "multi-beam partition" for global dilution of precision (DOP) optimization.

[0041] In view of this, as shown in the drawings, Figure 1 An embodiment of the present application provides a method for selecting satellites based on a multi-beam receiving antenna, which comprises: acquiring ephemeris of navigation satellites by using an omnidirectional receiving antenna, determining spatial positions of N visible satellites according to the ephemeris of the navigation satellites, N being a positive integer; transmitting M receiving beams by using the multi-beam receiving antenna and dividing the space uniformly into M regions, each receiving beam having a scanning beam angle, M scanning beam angles of the M receiving beams being mutually non-overlapping, M being a positive integer; classifying satellites with an elevation angle greater than or equal to a first threshold value and a carrier-to-noise ratio greater than or equal to a second threshold value in each region into a first candidate satellite set, obtaining M first candidate satellite sets; calculating a comprehensive quality score of each satellite in each first candidate satellite set according to the elevation angle of the satellite, the carrier-to-noise ratio of the satellite and an average spherical angular distance of the satellite within the scanning beam angle, obtaining the comprehensive quality score of each satellite in the M first candidate satellite sets; ranking the comprehensive quality scores of each satellite in each first candidate satellite set in descending order, retaining W satellites corresponding to the first W comprehensive quality scores, obtaining M second candidate satellite sets, W being a positive integer; selecting L satellites in the M second candidate satellite sets and calculating precision factors of the L satellites, selecting L satellites corresponding to the minimum value of the precision factors of the L satellites as the final selecting satellite result, L being a positive integer.

[0042] In a specific example, the navigation satellite ephemeris is received based on an omnidirectional receiving antenna, spatial positions of all visible satellites are determined according to the ephemeris, a receiving beam is initialized, a spatial range is divided according to a distribution and satellites are allocated, a satellite set is obtained by preliminary selection of an elevation angle and a carrier-to-noise ratio for each region, a comprehensive quality score is calculated for each satellite in the satellite set, and a plurality of satellites with the highest score are retained in each satellite set, and required satellites are selected from all candidate satellite sets so that a DOP value calculated by the required satellites is minimum.

[0043] The embodiment solves the problems that an omnidirectional antenna may introduce a large number of low-quality signals in a complex environment, thereby affecting signal quality and reducing positioning accuracy, and effectively improves the quality of signals received by a multi-beam receiving antenna; the satellite selection method with minimum precision factor supports periodic dynamic update, can quickly select the optimal satellite combination, is suitable for complex environments such as vehicle-mounted and airborne environments, and significantly improves positioning accuracy and robustness.

[0044] In a possible implementation, the determining of the spatial positions of the N visible satellites according to the navigation satellite ephemeris comprises: calculating unit direction vectors of the N visible satellites in a station-centered coordinate system based on a position of the omnidirectional receiving antenna.

[0045] In a specific example, in step S101, satellite ephemeris is acquired in real time based on an omnidirectional receiving antenna, and unit direction vectors of all visible satellites in a station-centered coordinate system are calculated based on a position of a current receiving system. i , i = 1, 2, …, N, and N is a total number of visible satellites.

[0046] In a specific example, in step S102, M receiving beams are provided to uniformly point to a surrounding space, M is greater than or equal to 4, a jth receiving beam in the M receiving beams has a limited scanning beam angle Ω j , Ω j is limited by the receiving system itself, where j = 1, 2, …, M, and the space can be uniformly divided into M regions θ j according to the M beams.

[0047] Further, the scanning beam angle Ω j of each beam of the M receiving beams does not overlap.

[0048] Further, the region θ j is defined by the following parameters in a station-centered coordinate system:

[0049] an azimuth start angle Az_start(j), an azimuth end angle Az_end(j), and an elevation lower limit El_low(j), an elevation upper limit El_high(j), and Az_end(j)-Az_start(j)≤180°; El_high(j)-El_low(j)≤90°.

[0050] In a possible implementation, the first threshold value ranges from 10° to 20°, and the second threshold value ranges from 30 dBHz to 40 dBHz.

[0051] In a specific example, step S103: for each area divided by each receiving beam, a satellite satisfying v i ∈θ j and an elevation angle El(v i )≥E min , and a carrier-to-noise ratio CN0(v i )≥C min is classified into a candidate satellite set C j , where E min and C min are preset threshold values.

[0052] Further, for example, E min may be selected from 10° to 20°, and C min may be selected from 30 dBHz to 40 dBHz.

[0053] In a possible implementation, the comprehensive quality score of each satellite in each first candidate satellite set is calculated according to the elevation angle of the satellite, the carrier-to-noise ratio of the satellite, and the average spherical angular distance of the satellite within the scanning beam angle.

[0054] Score(S)=w1·CN0(S)+w2·El(S)+w3·Dist(S,Ω j )

[0055] In the formula, Score(S) is the comprehensive quality score of the S-th satellite in the first candidate satellite set; w1 is the first weight coefficient, w2 is the second weight coefficient, w3 is the third weight coefficient, and 1=w1+w2+w3; CN0(S) is the elevation angle of the unit direction vector of the S-th satellite; El(S) is the carrier-to-noise ratio of the unit direction vector of the S-th satellite; Dist(S,Ω j ) is the average spherical angular distance of the satellite S within the scanning beam angle Ω j of the j-th receiving beam, j∈M.

[0056] In a specific example, step S104: the comprehensive quality score Score(S) of each satellite in C j is calculated, S∈Cj ,Score(S)=w1·CN0(S)+w2·El(S)+w3·Dist(S,Ω j ), where w1, w2, and w3 are preset weight coefficients;, Dist(S,Ω) j ) represents the satellite S within the beam scanning domain (i.e., the scanning beam angle Ω). j The average spherical angular distance; the weighting coefficients can be referenced as w1=0.5, w2=0.3, w3=0.2.

[0057] In one possible implementation, the scanning beam angle Ω of the satellite S in the j-th receiving beam is... j The formula for calculating the average spherical distance within is:

[0058]

[0059] In the formula, ∑() is the summation function; k is the scanning beam angle Ω. j There are k satellites in total, where k is a positive integer; arccos() is the inverse cosine function; v i v is the unit direction vector of the i-th satellite in the first candidate satellite set; s It is the unit direction vector of the S-th satellite in the first candidate satellite set.

[0060] In a specific example, C is calculated based on the unit vector of each satellite. j The angle between any two satellites, for a beam pointing towards satellite S, assuming the scanning beam angle (i.e., the beam scanning domain Ω) j If there are k satellites in a given area, the average spherical angular distance is calculated as follows: Dist(S,Ω) j )=∑(arccos(v i ·v S )) / k.

[0061] In a specific example, step S105: in each C j The top 1 to 3 satellites with the highest scores are retained.

[0062] In a specific example, step S106: select L satellites from the set of all M candidate satellites, where 4≤L≤M, such that the DOP value calculated from the L satellites is minimized.

[0063] In one possible implementation, selecting L satellites from the M second candidate satellite sets and calculating the precision factors of the L satellites includes: calculating the enumeration size, wherein the formula for calculating the enumeration size is:

[0064] Y = M·k

[0065] In the formula, Y is the enumeration size;

[0066] determining whether the enumeration scale is less than or equal to a third threshold value, if yes, calculating the precision factor of the L satellites by using an exhaustive method; if no, calculating the precision factor of the L satellites by using a greedy iteration method.

[0067] In a specific example, step S106: if the enumeration scale M·k≤P max , the exhaustive method is used to traverse all legal combinations and calculate the DOP; if M·k>P max , the greedy iteration method is used, including:

[0068] a) initializing the M sets with the satellites having the highest Score;

[0069] b) trying to replace the satellites in the same beam with suboptimal satellites one by one, and accepting if the DOP decreases and L≥4;

[0070] c) iterating until the DOP converges or the preset iteration number Iter_max is reached.

[0071] It should be noted that P max , Iter_max, ΔT, E min , C min and the weight coefficient can be set according to empirical values.

[0072] In a possible implementation, the method further includes: if the unit direction vector of any one of the N visible satellites is not in the corresponding region, updating the number of visible satellites and recalculating the final satellite selection result.

[0073] In a possible implementation, the method further includes: if the final satellite selection result is obtained and the unit direction vector of any one of the N visible satellites is in the corresponding region when the N visible satellites move within a preset period, calculating the final satellite selection result.

[0074] In a specific example, step S107: repeating steps S101 to S106 with a period of ΔT or when any satellite no longer satisfies v i ∈θ j , to dynamically update the composition of the N satellites, where ΔT can be selected from 1s to 5s.

[0075] In a possible implementation, the precision factor includes a geometric precision factor, a spatial position precision factor, a horizontal position precision factor or an elevation precision factor.

[0076] In a specific example, the precision factor (DOP) is a geometric precision factor (GDOP), a spatial position precision factor (PDOP), a horizontal position precision factor (HDOP) or an elevation precision factor (VDOP).

[0077] In a possible implementation, the multi-beam receiving antenna comprises a parabolic antenna, a patch array antenna, a phased array antenna, or a dielectric lens antenna.

[0078] In one specific example, the multi-beam receiving antenna is selected from a parabolic antenna, a patch array antenna, a phased array antenna, or a dielectric lens antenna.

[0079] In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected internally between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0080] It should also be noted that in the description of the present application, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0081] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not a limitation on the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A satellite selection method based on a multi-beam receiving antenna, characterized in that, The method includes: The ephemeris of navigation satellites is acquired using an omnidirectional receiving antenna, and the spatial positions of N visible satellites are determined based on the ephemeris, where N is a positive integer. The multi-beam receiving antenna transmits M receiving beams and divides the space into M regions evenly. Each receiving beam has a scanning beam angle, and the M scanning beam angles of the M receiving beams do not overlap. M is a positive integer. Satellites with an elevation angle greater than or equal to the first threshold and a carrier-to-noise ratio greater than or equal to the second threshold in each region are classified into the first candidate satellite set, resulting in M ​​first candidate satellite sets; The comprehensive quality score of each satellite in each first candidate satellite set is calculated based on the satellite's elevation angle, carrier-to-noise ratio, and average spherical angular distance within the scanning beam angle, resulting in the comprehensive quality scores of each satellite in the M first candidate satellite sets. The comprehensive quality scores of each satellite in each first candidate satellite set are sorted in descending order, and the W satellites corresponding to the top W comprehensive quality scores are retained to obtain M second candidate satellite sets, where W is a positive integer; Select L satellites from the set of M second candidate satellites and calculate the precision factor of L satellites. Select the L satellites corresponding to the minimum precision factor of the L satellites as the final satellite selection result, where L is a positive integer.

2. The satellite selection method for a multi-beam receiving antenna according to claim 1, characterized in that, The step of determining the spatial positions of N visible satellites based on the navigation satellite ephemeris includes: calculating the unit direction vectors of the N visible satellites in the station-centered coordinate system based on the position of the omnidirectional receiving antenna.

3. The satellite selection method for a multi-beam receiving antenna according to claim 2, characterized in that, The first threshold value ranges from 10° to 20°; the second threshold value ranges from 30dBHz to 40dBHz.

4. The satellite selection method for a multi-beam receiving antenna according to claim 3, characterized in that, The calculation of the comprehensive quality score for each satellite in each first candidate satellite set, based on the satellite's elevation angle, carrier-to-noise ratio, and average spherical angular distance within the scanning beam angle, includes: Score(S)=w1·CN0(S)+w2·El(S)+w3·Dist(S,Ω j ) In the formula, Score(S) is the overall quality score of the Sth satellite in the first candidate satellite set; w1 is the first weighting coefficient, w2 is the second weighting coefficient, and w3 is the third weighting coefficient, 1 = w1 + w2 + w3; CN0(S) is the elevation angle of the unit direction vector of the Sth satellite; El(S) is the carrier-to-noise ratio of the unit direction vector of the Sth satellite; Dist(S,Ω) is the carrier-to-noise ratio of the unit direction vector of the Sth satellite. j Ω is the scanning beam angle Ω of satellite S in the j-th receiving beam. j The average spherical angular distance within, j∈M.

5. The satellite selection method for a multi-beam receiving antenna according to claim 4, characterized in that, The scanning beam angle Ω of the satellite S in the j-th receiving beam. j The formula for calculating the average spherical distance within is: In the formula, ∑() is the summation function; k is the scanning beam angle Ω. j There are k satellites in total, where k is a positive integer; arccos() is the inverse cosine function; v i Let be the unit direction vector of the i-th satellite in the first candidate satellite set; v s It is the unit direction vector of the S-th satellite in the first candidate satellite set.

6. The satellite selection method for a multi-beam receiving antenna according to claim 5, characterized in that, The process of selecting L satellites from the M second candidate satellite sets and calculating the precision factors of the L satellites includes: The enumeration size is calculated using the formula: Y = M·k, where Y is the enumeration size. Determine whether the enumeration size is less than or equal to the third threshold. If so, use an exhaustive method to calculate the precision factor of L satellites. If not, then the greedy iterative method is used to calculate the accuracy factors of the L satellites.

7. The satellite selection method for a multi-beam receiving antenna according to claim 6, characterized in that, The method also includes: If the unit direction vector of any of the N visible satellites is not in the corresponding region, then update the number of visible satellites and recalculate the final satellite selection result.

8. The satellite selection method for a multi-beam receiving antenna according to claim 7, characterized in that, The method also includes: If the final satellite selection result is obtained and the unit direction vector of any of the N visible satellites is within the corresponding region when they move within the preset period, then the final satellite selection result is calculated and determined.

9. The satellite selection method for a multi-beam receiving antenna according to claim 8, characterized in that, The accuracy factors include: geometric accuracy factor, spatial position accuracy factor, horizontal position accuracy factor, or elevation accuracy factor.

10. The satellite selection method for a multi-beam receiving antenna according to claim 9, characterized in that, The multi-beam receiving antenna includes a parabolic antenna, a patch array antenna, a phased array antenna, or a dielectric lens antenna.

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