Multi-navigational star parallel searching and capturing method

Abstract

The invention discloses a multi-navigational satellite parallel searching and capturing method, which comprises the following steps of: selecting satellites which are symmetrically distributed on two sides of the earth according to the distribution characteristics of a navigational constellation orbital plane, combining the satellites together for combined searching, and judging whether three satellites are visible or not in a rapid capturing process through a multi-navigational satellite pseudo code weighted stacking method. The probabilistic Doppler and probabilistic code phase of the satellite can be judged under the visual condition, guidance information is provided for the next round of accurate capturing and tracking, and finally the position, possibly received by a current user, of the navigation satellite in an orbital plane is rapidly judged from a large area. Therefore, the problem that the existing satellite navigation receiver cannot quickly realize navigation positioning after cold start is effectively solved.

Description

Technical Field

[0001] The invention relates to the field of satellite navigation technology, and in particular to a method for parallel search and capture of multiple navigation stars. Background Art

[0002] Satellite navigation receivers are widely used in aerospace and other high-tech fields. Satellite navigation receivers consist of antennas and navigation processors. The antennas are generally placed at locations with good observation conditions on the surface of the user carrier to receive navigation signals from the zenith direction. The navigation processor receives the RF signal from the antenna, amplifies, filters and down-converts the RF signal, and then the baseband processing part completes the signal processing and navigation solution to calculate the position and speed. After a cold start, the satellite navigation receiver cannot know its own position and time parameters, and needs to capture and track possible navigation satellite signals in turn. After a round of blind search, the visible navigation satellite is captured and tracked to complete navigation positioning. Summary of the invention

[0003] The present invention provides a multi-navigation star parallel search and capture method to solve the problem that the existing navigation positioning cannot be realized quickly and effectively.

[0004] The present invention provides a multi-navigation star parallel search and capture method, the method comprising:

[0005] Selecting multiple satellites to form a satellite group, and setting the selected satellites to be a first satellite, a second satellite, and a third satellite;

[0006] based on Construct a composite pseudo code composed of multiple satellites, where prn1 is the pseudo code of the first satellite, prn2 is the pseudo code of the second satellite, prn3 is the pseudo code of the third satellite, and prn 1_2_3 It is a composite pseudo code containing pseudo code information of three satellites;

[0007] According to the composite pseudo code, through fft prn1_2_3 =FFT(prn 1_2_3 ) Calculate the FFT transform form of the combined pseudo code;

[0008] Receive the navigation signal and process it to obtain the sampling data If-data;

[0009] Performing FFT transformation on the sampled data If-data to obtain an FFT transformed form of the sampled data;

[0010] According to the calculated combined pseudo code FFT transform form and the combined pseudo code FFT transform form, a parallel method is adopted to The correlation result between the sampling data and the combined pseudo code data is calculated, wherein Rslt is the correlation result between the sampling data and the combined pseudo code data;

[0011] According to the correlation results between the sampling data and the combined pseudo code data, Calculate the energy of the correlation result, where Re(Rslt) is the real part of the correlation result Rslt, Im(Rslt) is the imaginary part of the correlation result Rslt, Energy for related results;

[0012] A group of frequency grids are rotated, and the navigation signal is received again and processed to obtain the sampled data If-data until the relevant result energy of all frequency grids is completed;

[0013] Get the maximum energy of the related result energy Second largest energy Average Energy The visibility of the navigation satellite is judged based on the numerical proportional relationship between the maximum energy, the second largest energy and the average energy. When it is determined that the user is not in the satellite signal coverage area of ​​the satellite group, a new satellite group consisting of multiple satellites perpendicular to the satellite orbit of the satellite group is constructed to further judge the visibility of the navigation satellite.

[0014] Optionally, the principle for selecting satellites in the satellite group is: according to the navigation satellite almanac, multiple navigation satellites distributed on both sides of the earth on the same orbital plane are selected to form a group.

[0015] Optionally, the selected satellites are two adjacent satellites on the same orbital plane for the satellites distributed on one side, and a satellite on the opposite side of the same orbital plane for the satellites distributed on the other side.

[0016] Optionally, receiving the navigation signal and processing it to obtain the sampling data If-data includes:

[0017] The navigation signal is received, amplified, filtered, down-converted and analog-to-digital converted. After the analog-to-digital conversion, the carrier is stripped according to the carrier frequency grid to obtain the sampled data If-data.

[0018] Optionally, performing FFT transformation on the sampled data If-data to obtain an FFT transformed form of the sampled data includes:

[0019] Perform FFT transformation on the sampled data If-data, that is, perform FFT If-data =FFT(If-data), and obtain the FFT transformed form of the sampled data.

[0020] Optionally, judging the visibility of the navigation satellite according to the numerical proportional relationship among the maximum energy, the second largest energy, and the average energy includes:

[0021] when , it is determined that the user is located in the signal coverage area of ​​the first satellite and the second satellite;

[0022] when , it is determined that the user is located in the coverage area of ​​the third satellite signal;

[0023] when , it is determined that the user is not in the signal coverage area of ​​the first satellite, the second satellite and the third satellite.

[0024] Optionally, constructing a new satellite group consisting of a plurality of satellites perpendicular to the satellite orbits of the satellite group and further determining the visibility of the navigation satellites includes:

[0025] When it is determined that the user is not in the satellite signal coverage area of ​​the satellite group, a new satellite group consisting of multiple satellites perpendicular to the satellite orbit of the satellite group is constructed, and the FFT transform form of the combined pseudocode is recalculated until the area where the user is located is determined.

[0026] Optionally, the satellites in the new satellite group are set to be the fourth satellite, the fifth satellite, and the sixth satellite, and the pseudo code composed of these three satellites is calculated. Among them, prn4 is the pseudo code of the fourth satellite, prn5 is the pseudo code of the fifth satellite, prn6 is the pseudo code of the sixth satellite, and prn 4_5_6 It is a composite pseudo code containing pseudo code information of three satellites, and then the FFT transform form of the combined pseudo code is recalculated until the area where the user is located is determined.

[0027] Optionally, after determining the area where the user is located, the method further includes: sequentially performing single-satellite precise capture in the area where the user is located, and performing navigation positioning based on the captured satellite signals to obtain the precise location of the user.

[0028] The beneficial effects of the present invention are as follows:

[0029] The present invention selects satellites symmetrically distributed on both sides of the earth for joint search based on the distribution characteristics of the navigation constellation orbital plane, and uses a multi-navigation satellite pseudo-code weighted superposition method to determine whether three satellites are visible during a rapid capture process. If visible, the probability Doppler and probability code phase of the satellite can be determined respectively, providing guidance information for the next round of precise capture and tracking, and ultimately achieving rapid determination of the position of the navigation satellite that the current user may receive in the orbital plane from a large area, thereby effectively solving the problem that the existing satellite navigation receiver cannot quickly achieve navigation positioning after cold start.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0032] Figure 1 A schematic diagram of a multi-navigation satellite parallel search according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of a multi-navigation satellite composite pseudo code according to an embodiment of the present invention;

[0034] Figure 3 Schematic diagram of parallel capture of multiple navigation satellites according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention.

[0036] To overcome the shortcomings of the prior art, the embodiments of the present invention provide a method for quickly searching for visible satellites in a satellite navigation receiver working environment under cold start conditions and determining the probability Doppler, thereby shortening the cold start first positioning time and improving the availability of satellite navigation under cold start conditions. Specifically, the method described in the embodiments of the present invention includes:

[0037] S101, selecting a plurality of satellites to form a satellite group, and setting the selected satellites to be a first satellite, a second satellite, and a third satellite;

[0038] It should be noted that there may be multiple satellites in the satellite group in the embodiment of the present invention, but for accurate calculation, the selected satellites should be at least three, and in specific implementation, the principle of selecting satellites in the satellite group in the embodiment of the present invention is: according to the navigation satellite almanac, multiple navigation satellites distributed on both sides of the earth on the same orbital plane are selected. It is also best to select two adjacent satellites on the same orbital plane for the satellites distributed on one side of the satellite group, and select a satellite on the opposite side on the same orbital plane for the satellites distributed on the other side.

[0039] S102, based on Construct a composite pseudo code composed of multiple satellites, where prn1 is the pseudo code of the first satellite, prn2 is the pseudo code of the second satellite, prn3 is the pseudo code of the third satellite, and prn 1_2_3 It is a composite pseudo code containing pseudo code information of three satellites;

[0040] S103, according to the composite pseudo code, through fft prn1_2_3 =FFT(prn 1_2_3 ) Calculate the FFT transform form of the combined pseudo code;

[0041] S104, receiving the navigation signal, processing to obtain sampled data If-data, and performing FFT transformation on the sampled data If-data to obtain an FFT transformed form of the sampled data;

[0042] Specifically, the embodiment of the present invention receives the navigation signal, performs amplification, filtering, down-conversion and analog-to-digital conversion, and after the analog-to-digital conversion, strips the carrier according to the carrier frequency grid to obtain the sampling data If-data.

[0043] Perform FFT transformation on the sampled data If-data to obtain the FFT transformed form of the sampled data, that is, perform FFT transformation on the sampled data If-data, that is, perform FFT If-data =FFT(If-data), and obtain the FFT transformed form of the sampled data.

[0044] S105, according to the calculated combined pseudo code FFT transformation form and the combined pseudo code FFT transformation form, adopt a parallel method, through The correlation result between the sampling data and the combined pseudo code data is calculated, wherein Rslt is the correlation result between the sampling data and the combined pseudo code data;

[0045] S106, according to the correlation results between the sampled data and the combined pseudo code data, Calculate the energy of the correlation result, where Re(Rslt) is the real part of the correlation result Rslt, Im(Rslt) is the imaginary part of the correlation result Rslt, Energy for related results;

[0046] S107, rotating a group of frequency grids, re-receiving the navigation signal and processing it to obtain the sampled data If-data, until the relevant result energy of all frequency grids is completed;

[0047] S108, obtaining the maximum energy of the related result energy Second largest energy Average Energy The visibility of the navigation satellite is determined based on the numerical proportional relationship between the maximum energy, the second largest energy, and the average energy;

[0048] Specifically, the embodiment of the present invention is when When , it is determined that the user is located in the signal coverage area of ​​the first satellite and the second satellite; when When , it is determined that the user is located in the coverage area of ​​the third satellite signal; when , it is determined that the user is not in the signal coverage area of ​​the first satellite, the second satellite and the third satellite.

[0049] S109: When it is determined that the user is not in the satellite signal coverage area of ​​the satellite group, a new satellite group consisting of multiple satellites perpendicular to the satellite orbits of the satellite group is constructed and the visibility of the navigation satellite is further determined.

[0050] When it is determined that the user is not in the satellite signal coverage area of ​​the satellite group, a new satellite group consisting of multiple satellites perpendicular to the satellite orbit of the satellite group is constructed, and the FFT transform form of the combined pseudocode is recalculated until the area where the user is located is determined.

[0051] Specifically, the method of the embodiment of the present invention is to set the satellites in the new satellite group to be the fourth satellite, the fifth satellite, and the sixth satellite, calculate the pseudo code composed of these three satellites, and calculate Among them, prn4 is the pseudo code of the fourth satellite, prn5 is the pseudo code of the fifth satellite, prn6 is the pseudo code of the sixth satellite, and prn 4_5_6 It is a composite pseudo code containing pseudo code information of three satellites, and then the FFT transform form of the combined pseudo code is recalculated until the area where the user's position is re-determined.

[0052] In specific implementation, the method described in the embodiment of the present invention also includes, after determining the area where the user is located, the method also includes: carrying out single-star precise capture in sequence in the area where the user is located, and carrying out navigation positioning based on the captured satellite signals to obtain the user's precise location.

[0053] In general, the method described in the embodiment of the present invention is to select satellites symmetrically distributed on both sides of the earth and combine them for joint search based on the distribution characteristics of the navigation constellation orbital plane, and quickly judge the position of the navigation satellite that the current user may receive in the orbital plane from a large area through the searched satellites. In addition, the embodiment of the present invention uses a multi-navigation satellite pseudo-code weighted superposition method to determine whether three satellites are visible during a rapid capture process. If visible, the probability Doppler and probability code phase of the satellite can be determined respectively, providing guidance information for the next round of precise capture and tracking. The capture method adopted by the present invention can be used for both serial capture and parallel rapid capture. Under the condition of insufficient logic resources, the capture time can be significantly improved, creating conditions for cutting parallel capture modules to save logic resources.

[0054] The following will be combined Figures 1 to 3 The method described in the embodiment of the present invention is explained and illustrated in detail by a specific example:

[0055] The embodiment of the present invention provides a method for quickly searching for visible satellites in a satellite navigation receiver working environment under cold start conditions and determining probabilistic Doppler, thereby shortening the cold start first positioning time and improving the availability of satellite navigation under cold start conditions. The method described in the embodiment of the present invention includes:

[0056] The present invention is applicable to satellite navigation equipment that starts blind capture. Under the premise that the own position and speed are unknown and the specific position of the navigation star cannot be obtained at an unknown time, before carrying out patrol capture of each satellite, three satellites are taken as a group, and a capture operation is performed to determine whether the three satellites are visible. If there are visible satellites, it is determined which satellite is visible, so as to provide guidance information for the next round of precise capture and tracking.

[0057] The present invention provides a method for parallel search and capture of multiple navigation stars, comprising the following steps:

[0058] (1) According to the navigation satellite almanac, select three navigation satellites distributed on the same orbital plane on both sides of the earth to form a group. Among them, the satellites distributed on one side are selected from two adjacent satellites on the same orbital plane. The satellites distributed on the other side are selected from a satellite on the same orbital plane on the opposite side. Figure 1 As shown, select 1#, 5#, and 3# satellites to form a satellite group;

[0059] (2) The satellite group obtained according to step (1) is as follows: Figure 2 As shown, based on Construct a composite pseudo code composed of multiple satellites, where prn1 is the pseudo code of satellite #1, prn5 is the pseudo code of satellite #5, prn3 is the pseudo code of satellite #3, and prn 1_5_3 It is a composite pseudo code containing pseudo code information of three satellites;

[0060] (3) According to the composite pseudocode obtained in step (2), calculate the FFT transform form of the combined pseudocode. The specific formula is: prn1_5_3 =FFT(prn 1_5_3 );

[0061] (4) The satellite navigation receiver receives the navigation signal, amplifies, filters and down-converts it, and after analog-to-digital conversion, strips the carrier according to the carrier frequency grid to obtain the sampled data If-data;

[0062] (5) Perform FFT transformation on the sampled data If-data obtained in step (4) to obtain the FFT transformation form of the sampled data. The specific formula is fft If-data =FFT(If-data);

[0063] (6) Based on the combined pseudo-code FFT transformation form obtained in step (5) and the sampled data FFT transformation form obtained in step (2), a correlation result between the sampled data and the combined pseudo-code data is calculated in parallel. The specific formula is: Among them, Rslt is the correlation result between the sampling data and the combined pseudo code data.

[0064] (7) According to the correlation results between the sampled data and the combined pseudo code data obtained in step (6), the energy of the correlation result is calculated. The specific formula is:

[0065] Among them, Re(Rslt) is the real part of the correlation result Rslt, and Im(Rslt) is the imaginary part of the correlation result Rslt. Energy for related results;

[0066] (8) rotating a group of frequency grids, repeating steps (4) to (7) to complete the relevant result energy of all frequency grids;

[0067] (9) Obtain the maximum energy of the relevant result energy Second largest energy Average Energy

[0068] (10) Determine the visibility of the navigation satellite based on the numerical proportional relationship between the maximum energy, the second largest energy, and the average energy. Specifically:

[0069] When the maximum energy, the second largest energy, and the average energy meet When the user is in the coverage area of ​​Sat1 and Sat5 satellite signals, it can be determined that the user is in the coverage area of ​​Sat1 and Sat5 satellite signals;

[0070] When the maximum energy, the second largest energy, and the average energy meet When the user is in the Sat3 satellite signal coverage area, it can be determined that the user is in the Sat3 satellite signal coverage area;

[0071] When the maximum energy, the second largest energy, and the average energy meet When the user is not in the coverage area of ​​Sat1, Sat5, or Sat3 satellite signals,

[0072] (11) According to the result obtained in step (10), when it is determined that the user is not in the coverage area of ​​the Sat1, Sat5, and Sat3 satellite signals, a pseudo code consisting of multiple satellites (Sat2, Sat6, and Sat4) perpendicular to the orbits of the Sat1, Sat5, and Sat3 satellites is constructed. The specific formula is:

[0073] Among them, prn2 is the pseudo code of satellite #2, prn6 is the pseudo code of satellite #6, prn4 is the pseudo code of satellite #4, and prn 2_6_4 It is a composite pseudo code containing pseudo code information of three satellites;

[0074] Repeat steps (3) to (10) to determine the area where the user is located.

[0075] (12) Based on the results of step (10) and step (11), single-satellite precise capture is performed in sequence in the area where the user is located. For example, when the user is located in the area under the 4# satellite, when it is determined that the user is located in the area under the 4# satellite, the traditional method is used to successively perform capture and tracking of the 4#, 8#, 14#, and 18# satellites;

[0076] (13) Carry out navigation positioning based on the captured satellite signals to obtain the user’s precise location.

[0077] It can be seen from the above method that the present invention provides a parallel search and capture method suitable for quickly receiving navigation satellite signals. When the satellite navigation device is turned on and blindly captures, and has not yet obtained its own position and time, and has not yet obtained the visible satellite number, the present invention applies multi-navigation satellite pseudo-code weighted technology to realize a capture process to determine whether multiple satellites are visible, and provide probability information for the next stage of detailed capture and tracking, avoiding the capture and tracking of each satellite in turn when it is not determined that the satellite is visible, thereby enhancing the timeliness of the quick capture work and further improving the first positioning time under cold start conditions.

[0078] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, and thus, the scope of the present invention should not be limited to the above embodiments.

Claims

1. A multi-navigation star parallel search and capture method, characterized in that: The method comprises: Selecting multiple satellites to form a satellite group, and setting the selected satellites to be a first satellite, a second satellite, and a third satellite; based on Construct a composite pseudo code composed of multiple satellites, where prn1 is the pseudo code of the first satellite, prn2 is the pseudo code of the second satellite, prn3 is the pseudo code of the third satellite, and prn 1_2_3 It is a composite pseudo code containing pseudo code information of three satellites; According to the composite pseudo code, by Calculate the FFT transform form of the combined pseudocode; receiving a navigation signal and processing it to obtain sampled data If-data, and performing an FFT transformation on the sampled data If-data to obtain an FFT transformed form of the sampled data; According to the calculated combined pseudo code FFT transform form and the combined pseudo code FFT transform form, a parallel method is adopted to The correlation result between the sampling data and the combined pseudo code data is calculated, wherein Rslt is the correlation result between the sampling data and the combined pseudo code data; According to the correlation results between the sampling data and the combined pseudo code data, Calculate the energy of the correlation result, where Re(Rslt) is the real part of the correlation result Rslt, Im(Rslt) is the imaginary part of the correlation result Rslt, Energy for related results; A group of frequency grids are rotated, and the navigation signal is received again and processed to obtain the sampled data If-data until the relevant result energy of all frequency grids is completed; Get the maximum energy of the related result energy Second largest energy Average Energy The visibility of the navigation satellite is judged according to the numerical proportional relationship among the maximum energy, the second largest energy and the average energy. When it is determined that the user is not in the satellite signal coverage area of ​​the satellite group, a new satellite group consisting of multiple satellites perpendicular to the satellite orbit of the satellite group is constructed to further judge the visibility of the navigation satellite.

2. The method according to claim 1, characterized in that The principle for selecting satellites in the satellite group is: according to the navigation satellite almanac, multiple navigation satellites distributed on both sides of the earth on the same orbital plane are selected.

3. The method according to claim 2, characterized in that The satellites distributed on one side of the satellite group are selected from two adjacent satellites on the same orbital plane, and the satellites distributed on the other side are selected from a satellite on the opposite side of the same orbital plane.

4. The method according to claim 1, characterized in that: The received navigation signal is processed to obtain the sampled data If-data, including: The navigation signal is received, amplified, filtered, down-converted and analog-to-digital converted. After the analog-to-digital conversion, the carrier is stripped according to the carrier frequency grid to obtain the sampled data If-data.

5. The method according to claim 1, characterized in that Performing FFT transformation on the sampled data If-data to obtain an FFT transformation form of the sampled data includes: Perform FFT transformation on the sampled data If-data, that is, perform FFT If-data =FFT(If-data), and obtain the FFT transformed form of the sampled data.

6. The method according to any one of claims 1 to 5, characterized in that: The visibility of the navigation satellite is judged based on the numerical proportional relationship between the maximum energy, the second largest energy, and the average energy, including: when , it is determined that the user is located in the signal coverage area of ​​the first satellite and the second satellite; when , it is determined that the user is located in the coverage area of ​​the third satellite signal; when , it is determined that the user is not in the signal coverage area of ​​the first satellite, the second satellite and the third satellite.

7. The method according to any one of claims 1 to 5, characterized in that: Constructing a new satellite group consisting of a plurality of satellites perpendicular to the satellite orbits of the satellite group and further determining the visibility of the navigation satellites, including: When it is determined that the user is not in the satellite signal coverage area of ​​the satellite group, a new satellite group consisting of multiple satellites perpendicular to the satellite orbit of the satellite group is constructed, and the FFT transform form of the combined pseudocode is recalculated until the area where the user is located is determined.

8. The method according to claim 7, characterized in that Set the satellites in the new satellite group to be the fourth satellite, the fifth satellite, and the sixth satellite, and calculate the pseudo code composed of these three satellites. Among them, prn4 is the pseudo code of the fourth satellite, prn5 is the pseudo code of the fifth satellite, prn6 is the pseudo code of the sixth satellite, and prn 4_5_6 It is a composite pseudo code containing pseudo code information of three satellites, and then the FFT transform form of the combined pseudo code is recalculated until the area where the user's position is re-determined.

9. The method according to any one of claims 1 to 5, characterized in that: After determining the area where the user is located, the method further includes: sequentially carrying out single-satellite precise capture in the area where the user is located, and carrying out navigation positioning according to the captured satellite signals to obtain the precise location of the user.

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