A method and apparatus for implementing capture preprocessing

Abstract

A method and apparatus for acquisition preprocessing includes: estimating and determining the visible satellites of the navigation receiver within a preset time period based on satellite visibility association information of the navigation receiver; and performing acquisition processing based on the estimated visible satellites of the navigation receiver within the preset time period. Embodiments of the present invention reduce the number of satellites searched during cold start, shorten the initial positioning time during cold start, and improve the acquisition efficiency of the navigation receiver.

Description

Technical Field

[0001] This article relates to, but is not limited to, satellite navigation technology, and in particular to a method and apparatus for achieving acquisition preprocessing. Background Technology

[0002] Global Navigation Satellite Systems (GNSS) play an increasingly irreplaceable role in people's daily lives, especially in navigation, exploration, monitoring, surveying, and communication timing. With the rapid development of civilian applications in recent years, GNSS has become deeply integrated into daily life, appearing in everything from mobile phones, personal computers, cars, and civilian aircraft to missiles and fighter jets. Major countries around the world are striving to develop satellite navigation technology, resulting in multiple GNSS systems. These systems are both independently developing and compatible with each other, forming a thriving GNSS ecosystem. The main GNSS systems include the US GPS system, China's BeiDou (BD) system, Russia's GLONASS system, and Europe's Galileo system. In China and the Asia-Pacific region, GPS and BeiDou are more widely used; in Russia, GPS and GLONASS are more prevalent.

[0003] After receiving satellite signals through an antenna, the navigation receiver converts them to digital intermediate frequency (IF) signals via down-conversion and analog-to-digital (A / D) conversion. The digital IF signal then enters the signal channel for acquisition, tracking, bit synchronization, and frame synchronization processing. Finally, navigation calculations are performed to output the results. Acquisition plays a crucial role in the receiver's positioning process; satellite signal acquisition is a three-dimensional search process involving pseudocode, frequency, and time. The search time for a satellite signal depends on the uncertainty of the IF signal frequency f0 and the search range of the code phase. For example, the search range of the code phase for GPS satellite signals is 0–1023. Assuming the uncertainties of the signal frequency and code phase are f0 and f0 respectively... unc and t unc The search step size for frequency and code phase (i.e., bandwidth f) bin and code width t bin Then the number N of the search units can be calculated. cell for:

[0004]

[0005] Assume the search time for each search unit is T. dweel The time required to search the entire range of satellites is:

[0006] T one =N cell Tdwell (2)

[0007] The search of the entire constellation is completed based on the pseudo-random noise code (PRN) number of the satellite. If a satellite with a corresponding PRN number is confirmed to have a signal, then once the signal of that satellite is confirmed to have been acquired, the search units that have not yet completed their search do not need to continue searching. Statistically, the average acquisition time for confirming the presence of a signal from a satellite is [time missing]. Assuming the navigation satellite system has N satellites, and at a certain moment, the number of satellites visible to the receiver is n, then without valid ephemeris and time information, the time required for the receiver to complete the acquisition of all satellites is:

[0008] T tot =n*T acq +(Nn)*T one (3)

[0009] Currently, the main search strategies used in the acquisition process are simple and easy-to-implement linear search, but with a large computational load; parallel frequency search or parallel code phase search, which processes the code phase or frequency dimensions in parallel to reduce the number of search units; the latter two search methods reduce computation to some extent and improve acquisition efficiency; however, during cold start, it is still necessary to search all satellites in the system one by one. The receiver's first positioning time (TTFF) during cold start is an important criterion for judging the quality of the receiver, and cold start affects the acquisition efficiency of the navigation receiver. Summary of the Invention

[0010] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0011] This invention provides a method and apparatus for implementing acquisition preprocessing, which can reduce the number of satellites searched during cold start, shorten the initial positioning time during cold start, and improve the acquisition efficiency of navigation receivers.

[0012] This invention provides a method for implementing capture preprocessing, comprising:

[0013] Based on the satellite visibility correlation information of the navigation receiver, the visible satellites of the navigation receiver within a preset time period are estimated and determined;

[0014] The navigation receiver will acquire visible satellites within a predetermined timeframe based on the estimated duration.

[0015] Optionally, the estimation of visible satellites for the navigation receiver within a preset time period includes:

[0016] Based on the satellite's orbital altitude, Earth's radius, navigation receiver location, Earth's motion patterns, and satellite's orbital patterns, the entry and exit angles of visible satellites are calculated and determined.

[0017] Based on the determined entry and exit angles of the visible satellites, the distribution area of ​​the visible satellites within the preset time period is estimated and determined.

[0018] Based on the estimated distribution area and satellite distribution information of visible satellites within the preset time period, the visible satellites of the navigation receiver within the preset time period are estimated and determined.

[0019] Optionally, the Earth's motion law information includes: Earth's rotation angular velocity;

[0020] The satellite motion information includes the satellite's angular velocity in each orbit.

[0021] Optionally, the estimation of the distribution area of ​​visible satellites within a preset time period includes:

[0022] The corrected approach angle is obtained by adding a first preset offset angle to the determined approach angle of the visible satellite, and the corrected exit angle is obtained by reducing a second preset offset angle of the determined exit angle of the visible satellite.

[0023] Based on the corrected entry angle and the corrected exit angle, the distribution area of ​​visible satellites within the preset time period is estimated and determined.

[0024] Optionally, the acquisition process of visible satellites of the navigation receiver within a predetermined preset time period includes:

[0025] Based on the estimated number of visible satellites for the navigation receiver within the preset time period, determine the channel containing satellite signals;

[0026] Based on the determined channel containing satellite signals, determine the pseudo-random noise code (PRN) number of the satellite to be captured and the code phase of the corresponding signal;

[0027] Acquisition processing is performed based on the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

[0028] On the other hand, embodiments of the present invention also provide an apparatus for implementing capture preprocessing, comprising: an estimation unit and a capture processing unit; wherein,

[0029] The estimation unit is used to: estimate and determine the visible satellites of the navigation receiver within a preset time period based on the satellite visibility correlation information of the navigation receiver;

[0030] The acquisition processing unit is used to acquire visible satellites of the navigation receiver within a predetermined preset time period.

[0031] Optionally, the estimation unit is specifically used for:

[0032] Based on the satellite's orbital altitude, Earth's radius, navigation receiver location, Earth's motion patterns, and satellite's orbital patterns, the entry and exit angles of visible satellites are calculated and determined.

[0033] Based on the determined entry and exit angles of the visible satellites, the distribution area of ​​the visible satellites within the preset time period is estimated and determined.

[0034] Based on the estimated distribution area and satellite distribution information of visible satellites within the preset time period, the visible satellites of the navigation receiver within the preset time period are estimated and determined.

[0035] Optionally, the Earth's motion law information includes: Earth's rotation angular velocity;

[0036] The satellite motion information includes the satellite's angular velocity in each orbit.

[0037] Optionally, the estimation unit is used to estimate and determine the distribution area of ​​visible satellites within a preset time period, including:

[0038] The corrected approach angle is obtained by adding a first preset offset angle to the determined approach angle of the visible satellite, and the corrected exit angle is obtained by reducing a second preset offset angle of the determined exit angle of the visible satellite.

[0039] Based on the corrected entry angle and the corrected exit angle, the distribution area of ​​visible satellites within the preset time period is estimated and determined.

[0040] Optionally, the capture processing unit is specifically used for:

[0041] Based on the estimated number of visible satellites for the navigation receiver within the preset time period, determine the channel containing satellite signals;

[0042] Based on the determined channel containing satellite signals, determine the pseudo-random noise code (PRN) number of the satellite to be captured and the code phase of the corresponding signal;

[0043] Acquisition processing is performed based on the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

[0044] In another aspect, embodiments of the present invention also provide a computer storage medium storing computer-executable instructions for performing the above-described method.

[0045] Compared with related technologies, the technical solution of this application includes: estimating and determining the visible satellites of the navigation receiver within a preset time period based on the satellite visibility association information of the navigation receiver; and performing acquisition processing based on the estimated visible satellites of the navigation receiver within the preset time period. This embodiment of the invention reduces the number of satellites searched during cold start, shortens the initial positioning time during cold start, and improves the acquisition efficiency of the navigation receiver.

[0046] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0047] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0048] Figure 1 This is a flowchart illustrating the capture preprocessing method implemented in an embodiment of the present invention;

[0049] Figure 2 This is a structural block diagram of the apparatus for implementing capture preprocessing according to an embodiment of the present invention;

[0050] Figure 3 This is a schematic diagram illustrating the distribution of the satellite orbital plane and the Earth's cross-section as an application example of the present invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0052] The steps illustrated in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases the steps shown or described may be performed in a different order than that presented here.

[0053] Figure 1 This is a flowchart illustrating the capture preprocessing method implemented in an embodiment of the present invention, as shown below. Figure 1 As shown, it includes:

[0054] Step 101: Based on the satellite visibility correlation information of the navigation receiver, estimate and determine the visible satellites of the navigation receiver within a preset time period;

[0055] Optionally, in this embodiment of the invention, the estimation of visible satellites for the navigation receiver within a preset time period includes:

[0056] Based on the satellite's orbital altitude, Earth's radius, navigation receiver location, Earth's motion patterns, and satellite's orbital patterns, the entry and exit angles of visible satellites are calculated and determined.

[0057] Based on the determined entry and exit angles of the visible satellites, the distribution area of ​​the visible satellites within the preset time period is estimated and determined.

[0058] Based on the estimated distribution area and satellite distribution information of visible satellites within the preset time period, the visible satellites of the navigation receiver within the preset time period are estimated and determined.

[0059] Optionally, the Earth's motion law information in this embodiment of the invention includes: Earth's rotation angular velocity;

[0060] Optionally, the satellite motion law information in this embodiment of the invention includes: the angular velocity of the satellite in each orbit.

[0061] Optionally, in this embodiment of the invention, the estimation and determination of the distribution area of ​​visible satellites within a preset time period includes:

[0062] The corrected approach angle is obtained by adding a first preset offset angle to the determined approach angle of the visible satellite, and the corrected exit angle is obtained by reducing a second preset offset angle to the determined exit angle of the visible satellite.

[0063] Based on the corrected entry angle and the corrected exit angle, the distribution area of ​​visible satellites within the preset time period is estimated and determined.

[0064] It should be noted that the first preset offset angle can be a number greater than or equal to 0, and is generally set to a number greater than 0, such as 5 degrees. Generally, the first preset offset angle is less than 10 degrees. The first preset offset angle can be a number greater than or equal to 0, and is generally set to 0.

[0065] Step 102: Acquire visible satellites of the navigation receiver within the estimated preset time period.

[0066] Optionally, the acquisition process of visible satellites of the navigation receiver within a predetermined preset time period includes:

[0067] Based on the estimated number of visible satellites for the navigation receiver within the preset time period, determine the channel containing satellite signals;

[0068] Based on the determined channel containing satellite signals, determine the pseudo-random noise code (PRN) number of the satellite to be captured and the code phase of the corresponding signal;

[0069] Acquisition processing is performed based on the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

[0070] Compared with related technologies, the technical solution of this application includes: estimating and determining the visible satellites of the navigation receiver within a preset time period based on the satellite visibility association information of the navigation receiver; and performing acquisition processing based on the estimated visible satellites of the navigation receiver within the preset time period. This embodiment of the invention reduces the number of satellites searched during cold start, shortens the initial positioning time during cold start, and improves the acquisition efficiency of the navigation receiver.

[0071] Figure 2 This is a structural block diagram of the apparatus for implementing capture preprocessing according to an embodiment of the present invention, as shown below. Figure 2 As shown, it includes: a prediction unit and a capture processing unit; wherein,

[0072] The estimation unit is used to: estimate and determine the visible satellites of the navigation receiver within a preset time period based on the satellite visibility correlation information of the navigation receiver;

[0073] Optionally, in this embodiment of the invention, the estimation unit is specifically used for:

[0074] Based on the satellite's orbital altitude, Earth's radius, navigation receiver location, Earth's motion patterns, and satellite's orbital patterns, the entry and exit angles of visible satellites are calculated and determined.

[0075] Based on the determined entry and exit angles of the visible satellites, the distribution area of ​​the visible satellites within the preset time period is estimated and determined.

[0076] Based on the estimated distribution area and satellite distribution information of visible satellites within the preset time period, the visible satellites of the navigation receiver within the preset time period are estimated and determined.

[0077] Optionally, the Earth's motion law information in this embodiment of the invention includes: Earth's rotation angular velocity;

[0078] Optionally, the satellite motion law information in this embodiment of the invention includes: the angular velocity of the satellite in each orbit.

[0079] Optionally, the estimation unit is used to estimate and determine the distribution area of ​​visible satellites within a preset time period, including:

[0080] The corrected approach angle is obtained by adding a first preset offset angle to the determined approach angle of the visible satellite, and the corrected exit angle is obtained by reducing a second preset offset angle of the determined exit angle of the visible satellite.

[0081] Based on the corrected entry angle and the corrected exit angle, the distribution area of ​​visible satellites within the preset time period is estimated and determined.

[0082] The acquisition processing unit is used to acquire visible satellites of the navigation receiver within a predetermined preset time period.

[0083] Optionally, in this embodiment of the invention, the capture processing unit is specifically used for:

[0084] Based on the estimated number of visible satellites for the navigation receiver within the preset time period, determine the channel containing satellite signals;

[0085] Based on the determined channel containing satellite signals, determine the pseudo-random noise code (PRN) number of the satellite to be captured and the code phase of the corresponding signal;

[0086] Acquisition processing is performed based on the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

[0087] Compared with related technologies, the technical solution of this application includes: estimating and determining the visible satellites of the navigation receiver within a preset time period based on the satellite visibility association information of the navigation receiver; and performing acquisition processing based on the estimated visible satellites of the navigation receiver within the preset time period. This embodiment of the invention reduces the number of satellites searched during cold start, shortens the initial positioning time during cold start, and improves the acquisition efficiency of the navigation receiver.

[0088] This invention also provides a computer storage medium storing computer-executable instructions for performing the above-described method.

[0089] The following application examples clearly and in detail illustrate the methods of the embodiments of the present invention. These application examples are only used to describe the present invention and are not intended to limit the scope of protection of the present invention.

[0090] Application Examples

[0091] Global navigation satellite systems primarily rely on Medium Earth Orbit (MEO) satellites to provide navigation information and achieve positioning. Every complete satellite navigation system has a certain number of operational and backup MEO satellites, distributed in different orbits according to a pre-designed layout. Once an orbit is determined, the satellite remains in that orbit, which is approximately circular. There are fixed angles between satellites within the same operational orbit; for example, the GPS constellation has 24 satellites (actually around 30 in operation), with 4 satellites in each of 6 orbits. The angles between adjacent satellites are 30°, 105°, 120°, and 105°, respectively, totaling 360°.

[0092] The motion of a navigation receiver on the Earth's surface relative to a satellite is influenced by both the satellite's own motion and the Earth's rotation. For the same satellite navigation system, within the same region on the Earth's surface, the same constellation distribution is visible at regular intervals; this interval is called the constellation distribution repetition period, denoted as T0. Based on the satellite's distribution in its orbit and its motion, the constellation distribution of navigation receivers within a region at the positioning time is predicted using local time. The satellite orbits of the system are numbered 1, 2, ... i; the satellites within each orbit are numbered 1, 2, ... j. Once the satellite constellation design is complete, orbit i and its corresponding satellites are fixed. The numbering here has no specific order; it's only for ease of analysis. First, the solution information at a certain moment is known, i.e., the visible satellites and their information at the solution moment, and the solution time is used as the reference time (local time is sufficient). Theoretically, there is no limit to the length of the current solution time, but the accuracy of the two time records must be the same, i.e., the absolute time difference between the two time records must be accurate. The visible satellites at the reference time are then mapped to their respective orbits. The distribution of the satellite orbital plane and the Earth's cross-section is as follows: Figure 3 As shown, the navigation receiver is not in all orbital planes. For ease of analysis, the receiver's position is projected onto the satellite orbital plane using the Earth's surface as a projection. OR is equal to the Earth's radius. The great circle O represents the satellite orbit, and the small circle O represents the Earth's tangent plane within the satellite orbital plane. Satellites 1, 2, 3, 4, and j are in their orbits, and R represents the receiver on the Earth's surface. As shown in the diagram, satellites 1 and 2 are visible satellites. Based on satellite orbital patterns, satellite 1 is a satellite that is about to disappear, and satellite 3 is a satellite that is about to appear. Assume ∠AOB is the observation angle of receiver R within the satellite orbit, meaning the satellite is considered visible within this region; ∠AO1 is the departure angle, after which a visible satellite appears, making the departure angle invisible; ∠BO3 is the arrival angle, after which an invisible satellite appears, making the arrival angle visible.

[0093] The average altitude of the orbit is h0, and the average radius of the Earth is r0. Then ∠AOR is obtained by equation (4), and the receiver observation angle ∠AOB = 2∠AOR.

[0094]

[0095] Based on the information from satellite 1 at the reference time, the geometric distance R1 from the receiver to satellite 1 is calculated. Then, the departure angle ∠AO1 is calculated according to formula (5):

[0096]

[0097] The approach angle ∠BO3 is calculated according to formula (6):

[0098] ∠BO3=∠2O3-[∠AOB-(∠AO1+∠1O2)] (6)

[0099] With the navigation receiver as the reference point, the satellite's motion mainly consists of two parts: the satellite's rotation around the Earth and the Earth's rotation. The satellite's angular velocity n in its orbit... s for:

[0100]

[0101] Among them, T s Let n be the satellite's orbital period. The Earth's rotational angular velocity is n0. The angle between the satellite's orbital plane and the Earth's equatorial plane is θ. Then, the combined angular velocity n relative to the receiver satellite is... h According to equation (8), the result is:

[0102]

[0103] Calculate the interval T between the current time and the reference time based on the local time at the current location. int That is, there is T int =mT0+T frac , among which, T frac The time frame is less than one cycle. Since the visible satellites and their distribution are the same within the same region after each constellation cycle, the prediction only needs to consider the time frame that does not meet the one-cycle requirement.

[0104] according to Figure 3 Analysis and prediction indicate that satellites in orbit i are visible at the current positioning time. Assuming satellites in the same orbit have the same rotational angular velocity, then T... frac The rotation angle ΔΦ of each satellite relative to the receiver within the time orbit is:

[0105] ΔΦ=n h *T frac (9)

[0106] If ΔΦ>max(∠AO1,∠BO3), then the visible satellites on orbit i are satellite 2, satellite 3, or satellites whose ΔΦ is large enough to appear within the receiver's observation angle according to the approach and exit directions.

[0107] If ΔΦ<min(∠AO1,∠BO3), then the visible satellites on orbit i are satellite 1 and satellite 2;

[0108] If ∠AO1>∠BO3 and ∠BO3<ΔΦ<∠AO1, then the visible satellites on orbit i are satellite 1, satellite 2, and satellite 3;

[0109] If ∠AO1 < ∠BO3 and ∠AO1 < ΔΦ < ∠BO3, then the visible satellite on orbit i is satellite 2.

[0110] The visible satellites on orbit i at the current positioning time are obtained through the above analysis and processing. Similarly, the visible satellites on all orbits at the current positioning time can be obtained, thus obtaining all visible satellites of the navigation receiver at the current positioning time. Once the visible satellites of the receiver at the current time are obtained, it is determined which satellite signals are present in the channel. This determines the PRN number of the satellite to be acquired and the corresponding code phase of the signal. According to equations (1), (2), and (3), it can be seen that the above example processing reduces the search unit for each satellite, reduces the number of satellites searched, and increases the dwell time in each search unit within the allowed time. This reduces the receiver's acquisition time and improves acquisition sensitivity. The operation flowchart is shown below.

[0111] Assuming the current time is 17:00:00 on December 20, 2015, the GPS satellites visible to central China are: PRN 1, 7, 8, 9, 11, 16, 23, 26, 27, and 30; their corresponding elevation angles (in degrees) are 18.5, 43.0, 79.4, 33.0, 40.0, 26.3, 25.1, 6, 49.7, and 12.8, respectively. According to the GPS official satellite position table, satellites PRN 16 and 30 belong to the same orbit. Let satellite PAN 16 be satellite 1, and satellite PRN 30 be satellite 2, and their orbit be orbit 2. The position table shows that the angle between satellites 1 and 2 in their orbital plane is 30°. Based on the direction of their orbits, satellite 1 is about to disappear. Let satellite 3 be the satellite that will appear in orbit 2, and satellite 4 be the other satellite. According to the distribution of satellites in the same orbit in GPS, the angle between satellite 2 and satellite 3 is 105°, the angle between satellite 3 and satellite 4 is 120°, and the angle between satellite 4 and satellite 1 is 105°.

[0112] This application example predicts that the navigation receiver corresponding to the system satellite constellation is not a specific location, but rather a certain area where the navigation receiver is located. If the receiver is in that area at the same time, the visible stars of the receiver can all be predicted in this way. For ease of calculation, Wuhan is taken as the observation point, with coordinates (-2271601, 5009143, 3218833). Assuming that the average orbital altitude of the GPS satellites is 20200km and the average radius of the Earth is 6378km, according to Figure (1) and Equation (4), the observation angle of the observation point is ∠AOB=2∠AOR=152.23°; according to the satellite information at this time, the geometric distance between satellite 1 and the receiver is 22415901.76m. Figure 3 From the geometric relationship, we get ∠1OR = 43.825°. From equation (5), we get the exit angle ∠AO1 = 32.290°; from equation (6), we get the entry angle ∠BO3 = 15.060°.

[0113] If the GPS satellite orbital period is 11 hours and 58 minutes, then the average angular velocity of the satellite is n. s =1.458×10 -4 rad / s. The Earth's rotational angular velocity n0 = 7.292 × 10⁻⁶ rad / s. -5 rad / s. The angle between the GPS satellite's orbit and the equatorial plane is θ = 55°. From equation (8), the combined angular velocity is n. h =1.19911×10 -4 rad / s.

[0114] Predict the visible satellites in orbit 2 one hour after the reference time; from equation (9), the orbital rotation angle after one hour is ΔΦ = 24.7335°. Comparing ΔΦ with the entry angle and exit angle, we get ∠BO3 < ΔΦ < ∠AO1. According to the analysis above, the visible satellites in orbit 2 at the current time are satellite 1, satellite 2, and satellite 3, with corresponding PRN numbers 16, 28, and 30, respectively. Predicting other orbital satellites in this way, we can obtain the PRN numbers of the visible satellites at the current receiver as: 1, 7, 8, 9, 11, 16, 19, 27, 28, and 30.

[0115] At 18:00:00 on November 20, 2015, the predicted PRN numbers of the visible satellites for the navigation receiver were 1, 7, 8, 9, 11, 16, 19, 23, 27, 28, and 30. Comparing the predicted constellation with the actual constellation, there is a difference of one satellite, namely the satellite with PRN = 23. Based on the acquired satellite information, the elevation angle of satellite PRN = 23 is EL = 5.0°. Since the elevation angle is too small, it should be discarded in the actual calculation. Therefore, the visible satellites predicted by this algorithm are reliable.

[0116] Those skilled in the art will understand that all or part of the steps in the above methods can be implemented by a program instructing related hardware (e.g., a processor), and the program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk. Optionally, all or part of the steps in the above embodiments can also be implemented using one or more integrated circuits. Accordingly, each module / unit in the above embodiments can be implemented in hardware, such as by an integrated circuit to implement its corresponding function, or it can be implemented in the form of a software functional module, such as by a processor executing a program / instruction stored in memory to implement its corresponding function. This invention is not limited to any particular combination of hardware and software.

[0117] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes to the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for implementing capture preprocessing, characterized in that, include: Based on the satellite visibility correlation information of the navigation receiver, the visible satellites of the navigation receiver within a preset time period are estimated and determined; The navigation receiver will acquire and process the visible satellites within the estimated preset time period. The visible satellites of the navigation receiver within the preset time period, as estimated, include: Based on the satellite's orbital altitude, Earth's radius, navigation receiver location, Earth's motion information, and satellite motion information, the approach and exit angles of the visible satellite are calculated and determined. The Earth's motion information includes the Earth's rotational angular velocity; the satellite's motion information includes the satellite's angular velocity in each orbit. O is the center of the satellite's orbit, R is the Earth's surface receiver, OR equals the Earth's radius, and m1, m2, m3…m j Satellites are in orbit, with satellite m1 being a satellite that is about to disappear and satellite m3 being a satellite that is about to appear; the observation angle of receiver R within the satellite orbit is ∠AOB, where A and B are the points on the satellite orbit where the two sides of the observation angle ∠AOB fall, ∠AOm1 is the departure angle, and ∠BOm3 is the arrival angle. The average altitude of the orbit is... The average radius of the Earth is ∠AOB = 2∠AOR The geometric distance R1 from the receiver to satellite m1 is calculated from the information of satellite m1 at the reference time, and the departure angle is ∠AOm1. Based on the determined entry and exit angles of visible satellites and satellite distribution information, the visible satellites of the navigation receiver within the preset time period are estimated, wherein the angular velocity of the satellites in their orbits is... for , For the satellite's orbital period, Let be the Earth's rotational angular velocity; the angle between the satellite's orbital plane and the Earth's equatorial plane is . The combined angular velocity of the satellite relative to the receiver for The interval between the current local time and the reference time is... , , In less than one cycle, The rotation angle of each satellite relative to the receiver within the time orbit is... , ; if If the value is greater than max(∠AOm1, ∠BOm3), then the visible satellite in the orbit is satellite m3; if If the value is less than min(∠AOm1, ∠BOm3), then the visible satellite in the orbit is satellite m1. If ∠AOm1 is greater than ∠BOm3, and If the value is greater than ∠BOm3 but less than ∠AOm1, then the visible satellites in the orbit are satellite m1 and satellite m3. If ∠AOm1 is less than ∠BOm3, and If the value is greater than ∠AOm1 but less than ∠BOm3, then satellites m1 and m3 are not visible in orbit.

2. The method according to claim 1, characterized in that, When calculating and determining the approach and departure angles of a visible satellite based on the satellite's orbital altitude, Earth's radius, navigation receiver position, Earth's motion information, and satellite motion information, the method further includes: The determined approach angle of the visible satellite is increased by a first preset offset angle to obtain a corrected approach angle, and the determined exit angle of the visible satellite is decreased by a second preset offset angle to obtain a corrected exit angle.

3. The method according to claim 1, characterized in that, The acquisition process based on the visible satellites of the navigation receiver within a predetermined preset time period includes: Based on the estimated number of visible satellites for the navigation receiver within the preset time period, determine the channel containing satellite signals; Based on the determined channel containing satellite signals, determine the pseudo-random noise code (PRN) number of the satellite to be captured and the code phase of the corresponding signal; Acquisition processing is performed based on the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

4. An apparatus for implementing capture preprocessing, characterized in that, include: Prediction unit and capture processing unit; wherein, The estimation unit is used to: estimate and determine the visible satellites of the navigation receiver within a preset time period based on the satellite visibility correlation information of the navigation receiver; The acquisition processing unit is used to: acquire visible satellites of the navigation receiver within a predetermined preset time period; The visible satellites of the navigation receiver within the preset time period, as estimated, include: Based on the satellite's orbital altitude, Earth's radius, navigation receiver location, Earth's motion information, and satellite motion information, the approach and exit angles of the visible satellite are calculated and determined. The Earth's motion information includes the Earth's rotational angular velocity; the satellite's motion information includes the satellite's angular velocity in each orbit. O is the center of the satellite's orbit, R is the Earth's surface receiver, OR equals the Earth's radius, and m1, m2, m3…m j Satellites are in orbit, with satellite m1 being a satellite that is about to disappear and satellite m3 being a satellite that is about to appear; the observation angle of receiver R within the satellite orbit is ∠AOB, where A and B are the points on the satellite orbit where the two sides of the observation angle ∠AOB fall, ∠AOm1 is the departure angle, and ∠BOm3 is the arrival angle. The average altitude of the orbit is... The average radius of the Earth is ∠AOB = 2∠AOR The geometric distance R1 from the receiver to satellite m1 is calculated from the information of satellite m1 at the reference time, and the departure angle is ∠AOm1. Based on the determined entry and exit angles of visible satellites and satellite distribution information, the visible satellites of the navigation receiver within the preset time period are estimated, wherein the angular velocity of the satellites in their orbits is... for , For the satellite's orbital period, Let be the Earth's rotational angular velocity; the angle between the satellite's orbital plane and the Earth's equatorial plane is . The combined angular velocity of the satellite relative to the receiver for The interval between the current local time and the reference time is... , , In less than one cycle, The rotation angle of each satellite relative to the receiver within the time orbit is... , ; if If the value is greater than max(∠AOm1, ∠BOm3), then the visible satellite in the orbit is satellite m3; if If the value is less than min(∠AOm1, ∠BOm3), then the visible satellite in the orbit is satellite m1. If ∠AOm1 is greater than ∠BOm3, and If the value is greater than ∠BOm3 but less than ∠AOm1, then the visible satellites in the orbit are satellite m1 and satellite m3. If ∠AOm1 is less than ∠BOm3, and If the value is greater than ∠AOm1 but less than ∠BOm3, then satellites m1 and m3 are not visible in orbit.

5. The apparatus according to claim 4, characterized in that, The prediction unit is further configured to include: The determined approach angle of the visible satellite is increased by a first preset offset angle to obtain a corrected approach angle, and the determined exit angle of the visible satellite is decreased by a second preset offset angle to obtain a corrected exit angle.

6. The apparatus according to claim 4, characterized in that, The capture processing unit is specifically used for: Based on the estimated number of visible satellites for the navigation receiver within the preset time period, determine the channel containing satellite signals; Based on the determined channel containing satellite signals, determine the pseudo-random noise code (PRN) number of the satellite to be captured and the code phase of the corresponding signal; Acquisition processing is performed based on the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

7. A computer storage medium storing computer-executable instructions for performing the method of any one of claims 1 to 3.

Images