阅读说明：本技术 一种实现捕获预处理的方法及装置 (Method and device for realizing capture pretreatment ) 是由 宋挥师 赵海龙 徐雄伟 刘晓燕 于 2020-12-23 设计创作，主要内容包括：一种实现捕获预处理的方法及装置,包括：根据导航接收机的卫星可见的关联信息,预估确定预设时长内的导航接收机的可见卫星；根据预估确定的预设时长内的导航接收机的可见卫星进行捕获处理。本发明实施例减少了冷启动时搜索卫星的个数,缩短了冷启动首次定位时间提升了导航接收机的捕获效率。(A method and device for realizing capture preprocessing comprise: according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length; and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction. The embodiment of the invention reduces the number of the search satellites during cold start, shortens the first positioning time of cold start and improves the capturing efficiency of the navigation receiver.)

1. A method for implementing acquisition preprocessing, comprising:

according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length;

and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction.

2. The method of claim 1, wherein the pre-estimating the visible satellites of the navigation receiver for the predetermined duration comprises:

calculating and determining the entrance angle and the exit angle of the visible satellite according to the orbit height of the satellite, the radius of the earth, the position of the navigation receiver, the earth motion rule information and the satellite motion rule information;

according to the determined entrance angle and exit angle of the visible satellite, estimating and determining the distribution area of the visible satellite within the preset time length;

and according to the distribution area and the satellite distribution information of the visible satellites within the preset time length which are determined in a pre-estimation mode, the visible satellites of the navigation receiver within the preset time length are determined in a pre-estimation mode.

3. The method of claim 2,

the earth motion law information includes: the rotational angular velocity of the earth;

the satellite motion law information includes: angular velocity of the satellite's motion in each orbit.

4. The method of claim 2 or 3, wherein the pre-estimating for determining the distribution area of visible satellites within a preset time period comprises:

increasing a first preset offset angle to the determined entry angle of the visible satellite to obtain a corrected entry angle, and decreasing the determined exit angle of the visible satellite by a second preset offset angle to obtain a corrected exit angle;

and estimating and determining the distribution area of the visible satellites within the preset time according to the corrected entrance angle and the corrected exit angle.

5. The method according to any one of claims 1 to 3, wherein the acquiring according to the visible satellites of the navigation receiver within the preset time period determined by prediction comprises:

determining a channel containing satellite signals according to visible satellites of the navigation receiver within the preset time length determined by pre-estimation;

determining a pseudo-random noise code (PRN) number of a satellite to be acquired and a code phase of a corresponding signal according to the determined channel containing the satellite signal;

and performing acquisition processing according to the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

6. An apparatus for implementing capture preconditioning, comprising: the device comprises an estimation unit and a capture processing unit; wherein the content of the first and second substances,

the pre-estimating unit is used for: according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length;

the capture processing unit is to: and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction.

7. The apparatus according to claim 6, wherein the pre-estimating unit is specifically configured to:

calculating and determining the entrance angle and the exit angle of the visible satellite according to the orbit height of the satellite, the radius of the earth, the position of the navigation receiver, the earth motion rule information and the satellite motion rule information;

according to the determined entrance angle and exit angle of the visible satellite, estimating and determining the distribution area of the visible satellite within the preset time length;

and according to the distribution area and the satellite distribution information of the visible satellites within the preset time length which are determined in a pre-estimation mode, the visible satellites of the navigation receiver within the preset time length are determined in a pre-estimation mode.

8. The apparatus of claim 7,

the earth motion law information includes: the rotational angular velocity of the earth;

the satellite motion law information includes: angular velocity of the satellite's motion in each orbit.

9. The apparatus according to claim 6 or 7, wherein the estimating unit is configured to estimate the distribution area of visible satellites within a predetermined time period, and comprises:

increasing a first preset offset angle to the determined entry angle of the visible satellite to obtain a corrected entry angle, and decreasing the determined exit angle of the visible satellite by a second preset offset angle to obtain a corrected exit angle;

and estimating and determining the distribution area of the visible satellites within the preset time according to the corrected entrance angle and the corrected exit angle.

10. The apparatus according to any one of claims 6 to 8, wherein the capture processing unit is specifically configured to:

determining a channel containing satellite signals according to visible satellites of the navigation receiver within the preset time length determined by pre-estimation;

determining a pseudo-random noise code (PRN) number of a satellite to be acquired and a code phase of a corresponding signal according to the determined channel containing the satellite signal;

and performing acquisition processing according to the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

11. A computer storage medium having computer-executable instructions stored therein for performing the method of any one of claims 1-5.

Technical Field

The present disclosure relates to, but not limited to, satellite navigation technologies, and more particularly, to a method and apparatus for performing acquisition preprocessing.

Background

A Global Navigation Satellite System (GNSS) plays an increasingly irreplaceable important role in daily life of people, and is increasingly applied to the fields of Navigation, exploration, monitoring, measurement, communication time service and the like. With the rapid development of civil applications in recent years, a global satellite navigation system is gradually deepened in daily life, and the satellite navigation technology cannot be separated from mobile phones, personal computers, automobiles, civil airplanes, missiles and fighters. All major countries in the world strive to develop satellite navigation technology, a plurality of satellite navigation systems exist at present, and the countries are independent to compete to develop the satellite navigation technology and mutually compatible systems, so that a prosperous GNSS system is formed. The global satellite navigation system mainly comprises a GPS system in the United states, a Beidou (BD) system in China, a global navigation satellite positioning system (GLONASS) in Russia and a Galileo (Galileo) system in Europe; wherein, in China and Asia-Pacific region, GPS and Beidou are widely applied; in Russia, GPS and GLONASS are used more frequently.

After receiving satellite signals through an antenna, a navigation receiver obtains digital intermediate frequency signals through down-conversion and analog-to-digital (A/D) conversion; the digital intermediate frequency signal enters a signal channel to perform the following steps: capturing, tracking, bit synchronizing and frame synchronizing; and finally, carrying out navigation calculation and outputting a result. Acquisition plays an important role in the receiver's completion of positioning; acquisition of satellite signals is a three-dimensional search process with respect to pseudocode, frequency, and time. The duration of the search for a satellite signal depends on the frequency f of the intermediate frequency signal₀The search range of the uncertainty value and the code phase of (c); for example, the search range of the code phase of the GPS satellite signal is 0 to 1023; let f be the uncertainty values of the signal frequency and code phase, respectively_uncAnd t_uncStep size (i.e. bandwidth f) of frequency and code phase search_binSum code strip width t_bin) (ii) a The number N of search units is calculated_cellComprises the following steps:

suppose the search time of each search unit is T_dweelThen the time taken to search through the entire range of satellites is:

T_one＝N_cellT_dwell (2)

completing the search of the whole constellation according to a pseudo-random noise code (PRN) number of the satellite; if the satellite corresponding to the PRN number determines that there is a signal, the search unit that did not complete the search need not continue to complete the search after determining that the satellite signal was acquired. Statistically, the average acquisition time of the satellite containing the signal is determined asAssuming that the navigation satellite system has N satellites, and the number of visible satellites of the receiver at a certain time is N, the time required for the receiver to complete the acquisition tasks of all the satellites without valid ephemeris and time information is:

T_tot＝n*T_acq+(N-n)*T_one (3)

at present, the search strategy mainly adopted in the capturing process is simple and easy linear search, but the calculation amount is large; parallel frequency search or parallel code phase search, namely parallel processing is carried out on code phase or frequency dimension to reduce search units; the last two search modes reduce the operation to a certain extent and improve the capture efficiency; but at cold start it is also necessary to search all satellites in the system one by one. The Time To First Fix (TTFF) of the receiver at the cold start is an important criterion for determining the quality of the receiver, and the cold start affects the acquisition efficiency of the navigation receiver.

Disclosure of Invention

The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

The embodiment of the invention provides a method and a device for realizing capture preprocessing, which can reduce the number of search satellites during cold start, shorten the first positioning time of the cold start and improve the capture efficiency of a navigation receiver.

The embodiment of the invention provides a method for realizing capture pretreatment, which comprises the following steps:

according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length;

and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction.

Optionally, the predicting and determining the visible satellites of the navigation receiver within the preset time includes:

calculating and determining the entrance angle and the exit angle of the visible satellite according to the orbit height of the satellite, the radius of the earth, the position of the navigation receiver, the earth motion rule information and the satellite motion rule information;

according to the determined entrance angle and exit angle of the visible satellite, estimating and determining the distribution area of the visible satellite within the preset time length;

and according to the distribution area and the satellite distribution information of the visible satellites within the preset time length which are determined in a pre-estimation mode, the visible satellites of the navigation receiver within the preset time length are determined in a pre-estimation mode.

Optionally, the earth motion law information includes: the rotational angular velocity of the earth;

the satellite motion law information includes: angular velocity of the satellite's motion in each orbit.

Optionally, the predicting and determining the distribution area of the visible satellites within the preset time includes:

increasing a first preset offset angle to the determined entry angle of the visible satellite to obtain a corrected entry angle, and decreasing the determined exit angle of the visible satellite by a second preset offset angle to obtain a corrected exit angle;

and estimating and determining the distribution area of the visible satellites within the preset time according to the corrected entrance angle and the corrected exit angle.

Optionally, the capturing the visible satellites of the navigation receiver within the preset time period determined according to the prediction includes:

determining a channel containing satellite signals according to visible satellites of the navigation receiver within the preset time length determined by pre-estimation;

determining a pseudo-random noise code (PRN) number of a satellite to be acquired and a code phase of a corresponding signal according to the determined channel containing the satellite signal;

and performing acquisition processing according to the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

On the other hand, an embodiment of the present invention further provides an apparatus for implementing capture preprocessing, including: the device comprises an estimation unit and a capture processing unit; wherein the content of the first and second substances,

the pre-estimating unit is used for: according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length;

the capture processing unit is to: and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction.

Optionally, the estimating unit is specifically configured to:

calculating and determining the entrance angle and the exit angle of the visible satellite according to the orbit height of the satellite, the radius of the earth, the position of the navigation receiver, the earth motion rule information and the satellite motion rule information;

according to the determined entrance angle and exit angle of the visible satellite, estimating and determining the distribution area of the visible satellite within the preset time length;

and according to the distribution area and the satellite distribution information of the visible satellites within the preset time length which are determined in a pre-estimation mode, the visible satellites of the navigation receiver within the preset time length are determined in a pre-estimation mode.

Optionally, the earth motion law information includes: the rotational angular velocity of the earth;

the satellite motion law information includes: angular velocity of the satellite's motion in each orbit.

Optionally, the estimating unit is configured to estimate and determine a distribution area of the visible satellites within a preset time period, and includes:

increasing a first preset offset angle to the determined entry angle of the visible satellite to obtain a corrected entry angle, and decreasing the determined exit angle of the visible satellite by a second preset offset angle to obtain a corrected exit angle;

and estimating and determining the distribution area of the visible satellites within the preset time according to the corrected entrance angle and the corrected exit angle.

Optionally, the capture processing unit is specifically configured to:

determining a channel containing satellite signals according to visible satellites of the navigation receiver within the preset time length determined by pre-estimation;

determining a pseudo-random noise code (PRN) number of a satellite to be acquired and a code phase of a corresponding signal according to the determined channel containing the satellite signal;

and performing acquisition processing according to the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

In still another aspect, an embodiment of the present invention further provides a computer storage medium, where computer-executable instructions are stored in the computer storage medium, and the computer-executable instructions are configured to perform the method described above.

Compared with the related art, the technical scheme of the application comprises the following steps: according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length; and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction. The embodiment of the invention reduces the number of the search satellites during cold start, shortens the first positioning time of the cold start and improves the capturing efficiency of the navigation receiver.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the example serve to explain the principles of the invention and not to limit the invention.

FIG. 1 is a flow chart of a method for implementing capture pre-processing according to an embodiment of the present invention;

FIG. 2 is a block diagram of an apparatus for implementing capture preprocessing according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the distribution of the orbital planes and earth cross-sections of an exemplary satellite for use with the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.

The steps illustrated in the flow charts of the figures may be performed in a computer system such as a set of computer-executable instructions. Also, while a logical order is shown in the flow diagrams, in some cases, the steps shown or described may be performed in an order different than here.

Fig. 1 is a flowchart of a method for implementing capture preprocessing according to an embodiment of the present invention, as shown in fig. 1, including:

101, according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length;

optionally, the estimating and determining the visible satellites of the navigation receiver within the preset time duration in the embodiment of the present invention includes:

calculating and determining the entrance angle and the exit angle of the visible satellite according to the orbit height of the satellite, the radius of the earth, the position of the navigation receiver, the earth motion rule information and the satellite motion rule information;

according to the determined entrance angle and exit angle of the visible satellite, estimating and determining the distribution area of the visible satellite within the preset time length;

and according to the distribution area and the satellite distribution information of the visible satellites within the preset time length which are determined in a pre-estimation mode, the visible satellites of the navigation receiver within the preset time length are determined in a pre-estimation mode.

Optionally, the earth motion law information in the embodiment of the present invention includes: the rotational angular velocity of the earth;

optionally, the satellite motion law information in the embodiment of the present invention includes: angular velocity of the satellite's motion in each orbit.

Optionally, the determining, by prediction, the distribution area of the visible satellites within the preset time duration in the embodiment of the present invention includes:

increasing a first preset offset angle to the determined entry angle of the visible satellite to obtain a corrected entry angle, and decreasing the determined exit angle of the visible satellite by a second preset offset angle to obtain a corrected exit angle;

and estimating and determining the distribution area of the visible satellites within the preset time according to the corrected entrance angle and the corrected exit angle.

It should be noted that the first preset offset angle may be a number greater than or equal to 0, and is generally set to a number greater than 0, for example, 5 degrees of the first preset offset angle; generally, the first preset offset angle is less than 10 degrees; the first preset offset angle may be a number equal to or greater than 0, and is typically set to 0.

And 102, capturing the visible satellites of the navigation receiver within the preset time length determined by prediction.

Optionally, the capturing the visible satellites of the navigation receiver within the preset time period determined according to the prediction includes:

determining a channel containing satellite signals according to visible satellites of the navigation receiver within the preset time length determined by pre-estimation;

determining a pseudo-random noise code (PRN) number of a satellite to be acquired and a code phase of a corresponding signal according to the determined channel containing the satellite signal;

and performing acquisition processing according to the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

Compared with the related art, the technical scheme of the application comprises the following steps: according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length; and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction. The embodiment of the invention reduces the number of the search satellites during cold start, shortens the first positioning time of the cold start and improves the capturing efficiency of the navigation receiver.

Fig. 2 is a block diagram of an apparatus for implementing capture preprocessing according to an embodiment of the present invention, as shown in fig. 2, including: the device comprises an estimation unit and a capture processing unit; wherein the content of the first and second substances,

the pre-estimating unit is used for: according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length;

optionally, the estimation unit in the embodiment of the present invention is specifically configured to:

calculating and determining the entrance angle and the exit angle of the visible satellite according to the orbit height of the satellite, the radius of the earth, the position of the navigation receiver, the earth motion rule information and the satellite motion rule information;

according to the determined entrance angle and exit angle of the visible satellite, estimating and determining the distribution area of the visible satellite within the preset time length;

and according to the distribution area and the satellite distribution information of the visible satellites within the preset time length which are determined in a pre-estimation mode, the visible satellites of the navigation receiver within the preset time length are determined in a pre-estimation mode.

Optionally, the earth motion law information in the embodiment of the present invention includes: the rotational angular velocity of the earth;

optionally, the satellite motion law information in the embodiment of the present invention includes: angular velocity of the satellite's motion in each orbit.

Optionally, the estimating unit is configured to estimate and determine a distribution area of the visible satellites within a preset time period, and includes:

increasing a first preset offset angle to the determined entry angle of the visible satellite to obtain a corrected entry angle, and decreasing the determined exit angle of the visible satellite by a second preset offset angle to obtain a corrected exit angle;

and estimating and determining the distribution area of the visible satellites within the preset time according to the corrected entrance angle and the corrected exit angle.

The capture processing unit is to: and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction.

Optionally, the capture processing unit in the embodiment of the present invention is specifically configured to:

determining a channel containing satellite signals according to visible satellites of the navigation receiver within the preset time length determined by pre-estimation;

determining a pseudo-random noise code (PRN) number of a satellite to be acquired and a code phase of a corresponding signal according to the determined channel containing the satellite signal;

and performing acquisition processing according to the determined PRN number of the satellite to be acquired and the code phase of the corresponding signal.

Compared with the related art, the technical scheme of the application comprises the following steps: according to the satellite visible associated information of the navigation receiver, predicting and determining a visible satellite of the navigation receiver within a preset time length; and capturing the visible satellites of the navigation receiver within the preset time length determined by prediction. The embodiment of the invention reduces the number of the search satellites during cold start, shortens the first positioning time of the cold start and improves the capturing efficiency of the navigation receiver.

The embodiment of the invention also provides a computer storage medium, wherein computer-executable instructions are stored in the computer storage medium and used for executing the method.

The method of the embodiment of the present invention is described in detail below by using application examples, which are only used for illustrating the present invention and are not used for limiting the protection scope of the present invention.

Application example

The global satellite navigation system mainly depends on a medium circular orbit satellite (MEO) to provide navigation information to complete positioning. Each complete satellite navigation system has a number of working and spare MEO satellites distributed over different satellite orbits according to a predetermined design. Once the orbit is determined, the satellite will always be in its orbit, which is approximately circular. Different satellites in the same orbit have fixed included angles; for example, the GPS satellite constellation includes 24 satellites (actually, about 30 satellites are in operation), and 4 satellites in each orbit are distributed in 6 orbits, and the included angles between two adjacent satellites are 30 °,105 °,120 °,105 °, and 360 ° in sequence.

The movement of the earth surface navigation receiver relative to the satellite is, in addition to the movement of the satellite itself, the movement caused by the rotation of the earth. For the same satellite navigation system, the earth's surface is in the same region, and the same constellation distribution can be seen at certain time intervals, which are called constellation distribution repetition periods and are denoted as T₀. According to the distribution condition of the satellite in the orbit and the motion condition of the satellite, the local time is utilized to predict the constellation distribution of the navigation receiver in a region at the positioning moment. Numbering the satellite orbits of the system: 1. 2, … i; numbering the satellites in each orbit: 1. 2 … j, when the constellation design of the satellite is completed, the orbit i and the corresponding satellite are determined. The numbering here is not in order, but is done for ease of analysis. First, the calculation information at a certain time, that is, the visible satellites of the satellite at the time of calculation and the information thereof, is known, and the time of calculation is used as a reference time (local time is sufficient). The resolving time is theoretically not limited according to the length of the current resolving time, but the accuracy of the two time records is the same, namely the absolute time of the two time differences is accurate. And respectively corresponding the visible satellites at the reference time to the orbits of the visible satellites. The distribution of the satellite orbit plane and the earth section is shown in fig. 3, the navigation receiver is not in all orbit planes, the position of the receiver is projected to the satellite orbit plane from the earth surface for the convenience of analysis, OR is equal to the radius of the earth, the large circle O is the satellite orbit, the small circle O is the tangent plane of the earth in the satellite orbit plane, 1, 2, 3, 4, j are satellites in the orbit, and R is the receiver on the earth surface; as shown in the figure, the satellites 1 and 2 are visible satellites, and according to the operation rule of the satellites, the satellite 1 is a disappearing satellite and the satellite 3 is an emerging satellite. The condition that < AOB is the observation angle of the receiver R in the satellite orbit is assumed, namely the satellite is regarded as a visible satellite in the region; the angle AO1 is a driving angle, and after the driving angle is rotated, one visible satellite is arranged to change the driving angle into an invisible satellite; angle BO3 is the driving angle, after rotating the angleThere is one invisible satellite that changes the incoming observation angle to a visible satellite.

The average height of the track is h₀Average radius of the earth is r₀And then the angle AOR is obtained by the formula (4), and the receiver observation angle AOB is 2 angle AOR.

Calculating the geometric distance R1 from the receiver to the satellite 1 according to the information of the satellite 1 at the reference time, and calculating the driving angle AO1 according to the formula (5) as follows:

the driving-in angle & lt BO3 is calculated according to the formula (6) as follows:

∠BO3＝∠2O3-[∠AOB-(∠AO1+∠1O2)] (6)

the motion of the satellite mainly comprises two parts, namely the rotation motion of the satellite around the earth and the rotation of the earth by taking the navigation receiver as a reference point. Angular velocity n of movement of a satellite in orbit_sComprises the following steps:

wherein, T_sIs the satellite motion cycle. Rotational angular velocity of the earth is n₀. The angle between the orbital plane of the satellite and the equatorial plane of the earth is theta, the combined angular velocity n of the satellite relative to the receiver_hObtained according to equation (8) as:

according to the local time of the current positioning, the interval T between the current time and the reference time is calculated_intI.e. has T_int＝mT₀+T_fracWherein, T_fracLess than one weekThe time of the session. Since the visible satellites and the distribution in the same region are the same every other constellation repetition period, only the time which does not satisfy a period is considered in prediction.

From the analysis predictions of fig. 3, the orbit i has satellites in view at the current location time. If the rotational angular velocities of the satellites on the same orbit are the same, T_fracThe rotation angle Δ Φ of each satellite relative to the receiver in the time orbit is:

ΔΦ＝n_h*T_frac (9)

if delta phi is larger than max (angle AO1, angle BO3), the visible satellite on the orbit i is the satellite 2, the satellite 3 or delta phi is large enough, and the satellite finally appears in the observation angle of the receiver according to the driving-in direction and the driving-out direction;

if delta phi is less than min (angle AO1, angle BO3), the visible satellite on the orbit i is a satellite 1 and a satellite 2;

if the & lt AO1 & gt & lt BO3 and the & lt BO3 & lt delta & lt AO1, the visible satellites on the orbit i are the satellite 1, the satellite 2 and the satellite 3;

if the & lt AO1 & lt & gt BO3 and the & lt AO1 & lt delta & lt & gt & lt & gt BO3, the visible satellite on the orbit i is the satellite 2.

And obtaining the visible satellites on the orbit i at the current positioning time through the analysis processing. In the same way, all visible satellites in orbit at the current positioning time, that is, all visible satellites in the navigation receiver at the current positioning time, can be obtained. When the visible satellites of the receiver at the current time are obtained, the satellite signals are determined to be contained in the channel. This determines the PRN number of the satellite to be acquired and the code phase of the corresponding signal. From the expressions (1), (2), and (3), it can be seen that the search unit per satellite is reduced, the number of satellites searched is reduced, and the stay time per search unit increases within the allowable time by the above exemplary processing. Thereby reducing the acquisition time of the receiver and improving the acquisition sensitivity. The operation flow chart is as follows

Assuming that the current time is 2015, 12 months, 20 th, 17 hours, 00 minutes and 00 seconds, the satellites in the GPS constellation that are visible to the middle region of china are: PRN numbers 1, 7, 8, 9, 11, 16, 23, 26, 27, 30; the corresponding elevation angles (unit: degree) are respectively: 18.5, 43.0, 79.4, 33.0, 40.0, 26.3, 25.1, 6, 49.7, 12.8. By comparison of the star numbers provided by the GPS authorities, two satellites with PRN numbers 16 and 30 belong to the same satellite orbit. Let satellite 1 be PAN number 16, satellite 2 be PRN number 30, and the orbit in which both satellites are located be orbit 2. The star index table shows that the angle between the satellite 1 and the satellite 2 on the orbital plane is 30 degrees, and the satellite 1 is about to disappear according to the direction of the satellite operation. The satellite 3 is the upcoming satellite on the orbit 2, the other satellite is the satellite 4, and according to the distribution of the GPS satellites in the same orbit, the included angle between the satellite 2 and the satellite 3 is 105 °, the included angle between the satellite 3 and the satellite 4 is 120 °, and the included angle between the satellite 4 and the satellite 1 is 105 °.

The system satellite constellation predicted by the application example corresponds to a navigation receiver which is not a specific position, but a certain area where the navigation receiver is located. The visible stars of the receiver can be predicted in this way if the receiver is at the same time in the area. For the convenience of calculation, Wuhan is taken as an observation point, and coordinates are (-2271601, 5009143 and 3218833). Assuming that the average height of the orbit of the GPS satellite is 20200km, the average radius of the earth is 6378km, and the observation angle of an observation point is 152.23 degrees according to the graph (1) and the formula (4) when the angle AOB is 2 and AOR is 152.23 degrees; from the information on the satellite at this time, the geometric distance between the satellite 1 and the receiver is 22415901.76 m. From the geometric relationship of fig. 3, angle 1OR is 43.825 °. The angle of departure obtained by the formula (5) is equal to AO1 which is 32.290 degrees; the entry angle BO3 is 15.060 ° from equation (6).

The running period of the GPS satellite is 11 hours and 58 minutes, the average running angular speed of the satellite is n_s＝1.458×10^-4rad/s. Rotational angular velocity n of the earth₀＝7.292×10^-5rad/s. The combined angular velocity n obtained from the equation (8) is 55 ° with respect to the angle θ between the orbit of the GPS satellite and the equatorial plane_h＝1.19911×10^-4rad/s。

Predicting a visible satellite of orbit 2 after 1 hour from a reference time; the orbital rotation angle of 1 hour in equation (9) is Δ Φ 24.7335 °. Comparing delta phi with an entrance angle and an exit angle to obtain < BO3 < delta phi < AO1, and according to the analysis, the visible satellites of the orbit 2 at the current time are the satellite 1, the satellite 2 and the satellite 3, and the corresponding PRN numbers are 16, 28 and 30 respectively. The PRN numbers of the current receiver visible satellites obtained by predicting other orbiting satellites in this way are: 1.7, 8, 9, 11, 16, 19, 27, 28, 30.

PRN numbers 1, 7, 8, 9, 11, 16, 19, 23, 27, 28, and 30 are estimated for visible satellites of the navigation receiver at 18 hours, 0 minutes, and 0 seconds of 11/20/2015. Comparing the predicted constellation with the actual constellation differs by one satellite, namely the satellite with PRN 23. From the acquired satellite information, it can be known that the elevation angle of the satellite PRN 23 is equal to 5.0 °, and the satellite PRN should be eliminated in the actual calculation because the elevation angle is too small. The algorithm predicts that the satellites in view are reliable.

It will be understood by those skilled in the art that all or part of the steps of the above methods may be implemented by a program instructing associated hardware (e.g., a processor) to perform the steps, and the program may be stored in a computer readable storage medium, such as a read only memory, a magnetic or optical disk, and the like. Alternatively, all or part of the steps of the above embodiments may be implemented using one or more integrated circuits. Accordingly, each module/unit in the above embodiments may be implemented in hardware, for example, by an integrated circuit to implement its corresponding function, or in software, for example, by a processor executing a program/instruction stored in a memory to implement its corresponding function. The present invention is not limited to any specific form of combination of hardware and software.

Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.