Satellite navigation receiver cold start long code signal capture method, device and medium

Abstract

The present application relates to a method, device and medium for cold-start long code signal capture of a satellite navigation receiver. The method generates a minimized initial list of satellites to be captured, greatly compresses the search space of different satellites, and performs local time calibration of the receiver through the first satellite captured in the list, and then performs parallel capture of the remaining satellites, which can effectively reduce the cold-start time of the receiver and realize the rapid capture of the long code signal during the cold-start of the receiver.

Description

Technical Field

[0001] The present application relates to the field of satellite navigation technology, and in particular to a method, device and medium for cold-starting long code signal capture of a satellite navigation receiver. Background Art

[0002] The radio navigation positioning signals transmitted by multiple global navigation satellite systems (GNSS) have two different coding methods: short code and long code. Short code, also known as civil code, provides public services to the public. The ranging code of short code signal generally adopts a pseudo code with a period of 1ms and has a short periodicity; long code signal is an authorization signal, also known as precise ranging code, with a long periodicity or no periodicity.

[0003] The traditional long code signal capture method is to indirectly capture the long code through short code guidance, that is, first receive the short code signal, obtain the current precise time, and then capture the long code signal. However, in some cases, the short code signal may be subject to external interference, or in order to prevent being deceived, the satellite navigation receiver will directly capture the long code signal. In direct capture under cold start conditions, the receiver needs to implement periodic blind capture of the long code signal, which can be understood as capturing the visible satellite that transmits the long code signal by periodically calculating non-instantaneous parameters such as the almanac within a certain time uncertainty range. The capture of long code signals during cold start is a three-dimensional search process, which requires searching for different satellites, searching for satellite signal carrier frequencies, and searching for pseudo-random code phases. Even blind capture of a single satellite takes a long time. When the long code signal receiver is turned on, it will have external timing. The time uncertainty range is usually ±1s, and the pseudo-random code search step is usually 0.5 code chips. Taking the GPS long code signal P code as an example, the P code cold start needs to search for the code phase of ±1s time length, that is, in the worst case, it needs to search 40920000 times to search for the long code signal transmitted by a satellite. Assuming that the parallel search takes 1ms every 100 times, it will take about 409.20s. If the search for the star fails, the search time will increase exponentially. Once the first satellite can be quickly captured, the local time of the receiver can be calibrated to obtain a more accurate local time. Due to the improvement of time accuracy, the code phase ambiguity is significantly reduced, and the time required for capture and hardware processing resources are greatly reduced. On this basis, the long code signals transmitted by other satellites can be captured in parallel. Therefore, how to quickly capture the long code signal of the first satellite is the biggest difficulty in achieving fast capture of long code signals when the satellite navigation receiver is cold started. Summary of the invention

[0004] Based on this, it is necessary to provide a method, device and medium for cold-start long code signal capture of a satellite navigation receiver in response to the above technical problems.

[0005] A method for cold-starting a long code signal acquisition of a satellite navigation receiver, the method comprising:

[0006] Step 1: For a single-constellation satellite navigation system, calculate and obtain the position distribution of all satellites that transmit long code signals;

[0007] Step 2, calculate and obtain the angle between the space vectors corresponding to any two satellites;

[0008] Step 3, select one satellite in turn as the vertex of the approximate regular tetrahedron, and according to the angle between the vertex satellite and the space vectors corresponding to other satellites, search for the satellite set corresponding to the vertex satellite that satisfies the construction of the other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center;

[0009] Step 4, sort the bottom vertex satellite set corresponding to each satellite in descending order of the number of satellites;

[0010] Step 5, sequentially selecting three satellites from the bottom vertex satellite set and their corresponding vertex satellites to construct an approximate regular tetrahedron, and the four satellites constituting the approximate regular tetrahedron form an initial list of satellites to be captured;

[0011] Step 6, capture the satellites in the initial list of satellites to be captured in sequence. If the first satellite emitting a long code signal is successfully captured, proceed to step 7; if the capture of the four satellites in the initial list of satellites to be captured fails, return to step 5, reselect four satellites that form a new approximate regular tetrahedron as a new list of satellites to be captured, and continue to capture satellites in the new list of satellites to be captured until the first satellite emitting a long code signal is successfully captured;

[0012] Step 7, use the first satellite captured to calibrate the local time of the receiver, and perform parallel capture of the remaining satellites based on the local time-calibrated receiver;

[0013] Step 8: The receiver obtains observation information and ephemeris parameters in real time from the long code signals transmitted by all successfully captured satellites until the receiver achieves the first positioning and the receiver cold start is completed.

[0014] In one embodiment, for a single-constellation satellite navigation system, calculating and obtaining the position distribution of all satellites transmitting long code signals includes:

[0015] For single-constellation satellite navigation systems, the approximate spatial positions of all satellites transmitting long code signals are calculated based on the approximate time and the valid almanac parameters saved by the receiver.

[0016] In one embodiment, calculating and obtaining the angle between the space vectors corresponding to any two satellites includes:

[0017] In the Earth-centered Earth-fixed coordinate system, the space vector corresponding to the satellite is obtained according to the approximate spatial position of the satellite, and the angle between the space vectors corresponding to any two satellites is calculated according to the vector angle calculation formula, which is expressed as

[0018] ;

[0019] in, and Respectively represent Satellites and Satellites The corresponding space vector is, and They are and The model, express and The angle between , ,and , Indicates the total number of satellites transmitting long code signals.

[0020] In one embodiment, one satellite is selected in turn as a vertex of an approximate regular tetrahedron, and according to the angle between the space vectors corresponding to the vertex satellite and other satellites, a satellite set corresponding to the vertex satellite that satisfies the construction of other vertices of the bottom surface of an approximate regular tetrahedron with the center of the earth as the body center is searched, including:

[0021] Select Satellite As the vertices of the approximate regular tetrahedron, and search for vertex satellites Correspondingly, the satellite set of other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center is satisfied, and the satellite set is recorded as the bottom surface vertex satellite set ,in, The space vector corresponding to the mid-satellite and the vertex satellite The angle between the corresponding space vectors The satisfied angle range constraint is expressed as

[0022] ;

[0023] in, The angle between the vectors from each vertex to the center of the earth is the size of the angle between the vertices of the tetrahedron and the vertices of the bottom surface when the vertices of the tetrahedron and the bottom surface form a regular tetrahedron tangent to the earth. At this time, the earth is assumed to be a perfect sphere. Since the satellites in the single-constellation satellite navigation system are all medium- and high-orbit satellites, the actual distance to the center of the earth is greater than the distance from the vertex of the regular tetrahedron tangent to the earth to the center of the earth. The angle between the vectors from each vertex of the constructed approximate regular tetrahedron to the center of the earth is smaller than The size of allows a certain offset, and this angle offset is recorded as the redundant angle .

[0024] In one embodiment, the bottom vertex satellite set corresponding to each satellite is sorted in descending order of the number of satellites, including:

[0025] According to the order of satellite numbers from large to small, the bottom vertex satellite sets corresponding to each vertex satellite are sorted to obtain the bottom vertex satellite set sequence, which is expressed as ;in, is the total number of satellites transmitting long code signals, Indicates The satellite set of the bottom vertex, express The satellites, for The total number of satellites in , Indicates n The satellite set of the bottom vertex The total number of satellites in .

[0026] In one embodiment, three satellites are sequentially selected from the bottom vertex satellite set to construct an approximate regular tetrahedron with their corresponding vertex satellites, and the four satellites constituting the approximate regular tetrahedron form an initial list of satellites to be captured, including:

[0027] The satellites are assembled in order at the bottom vertices Select three satellites that approximately form an equilateral triangle, and construct an approximate regular tetrahedron based on these three satellites and their corresponding vertex satellites; the selection rule of the three satellite combination G that approximately forms an equilateral triangle is:

[0028] Satellite collection at the bottom vertex Select the j Satellites As the first satellite in satellite group G, and Search and satellite The angle between the corresponding space vectors is Satellite collection within the interval , if the satellite collection Does not exist or the subsequent step is in the satellite collection If the second or third satellite of satellite combination G cannot be selected, update j=j+1 and repeat the step; j The initial value of ; Represents a satellite collection The lsatellites;

[0029] Meet at Satellite Select the p Satellites As the second satellite in satellite group G, and in satellite group Search and satellite The angle between the corresponding space vectors is Satellite collection within the interval , if the satellite collection If it does not exist, update p=p+1 and repeat the step; where, p The initial value of ; Represents a satellite collection The k satellites;

[0030] If the satellites gather If exists, then in the satellite set Select any satellite as the third satellite in the satellite combination G, and combine the three satellites in the satellite combination G and their corresponding vertex satellites to form an initial list of satellites to be captured.

[0031] In one embodiment, the local time of the receiver is calibrated using the first satellite captured, and the remaining satellites are captured in parallel based on the local time-calibrated receiver, including:

[0032] The single-satellite calibration method is used to calibrate the local time of the receiver using the first captured satellite that transmits a long code signal, and the remaining satellites are captured in parallel based on the local time-calibrated receiver. During the parallel capture process, some invisible stars are eliminated based on the angle relationship between the space vectors corresponding to the remaining satellites and the first captured satellite, thereby further narrowing the satellite capture range.

[0033] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0034] Step 1: For a single-constellation satellite navigation system, calculate and obtain the position distribution of all satellites that transmit long code signals;

[0035] Step 2, calculate and obtain the angle between the space vectors corresponding to any two satellites;

[0036] Step 3, select one satellite in turn as the vertex of the approximate regular tetrahedron, and according to the angle between the vertex satellite and the space vectors corresponding to other satellites, search for the satellite set corresponding to the vertex satellite that satisfies the construction of the other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center;

[0037] Step 4, sort the bottom vertex satellite set corresponding to each satellite in descending order of the number of satellites;

[0038] Step 5, sequentially selecting three satellites from the bottom vertex satellite set and their corresponding vertex satellites to construct an approximate regular tetrahedron, and the four satellites constituting the approximate regular tetrahedron form an initial list of satellites to be captured;

[0039] Step 6, capture the satellites in the initial list of satellites to be captured in sequence. If the first satellite emitting a long code signal is successfully captured, proceed to step 7; if the capture of the four satellites in the initial list of satellites to be captured fails, return to step 5, reselect four satellites that form a new approximate regular tetrahedron as a new list of satellites to be captured, and continue to capture satellites in the new list of satellites to be captured until the first satellite emitting a long code signal is successfully captured;

[0040] Step 7, use the first satellite captured to calibrate the local time of the receiver, and perform parallel capture of the remaining satellites based on the local time-calibrated receiver;

[0041] Step 8: The receiver obtains observation information and ephemeris parameters in real time from the long code signals transmitted by all successfully captured satellites until the receiver achieves the first positioning and the receiver cold start is completed.

[0042] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps:

[0043] Step 1: For a single-constellation satellite navigation system, calculate and obtain the position distribution of all satellites that transmit long code signals;

[0044] Step 2, calculate and obtain the angle between the space vectors corresponding to any two satellites;

[0045] Step 3, select one satellite in turn as the vertex of the approximate regular tetrahedron, and according to the angle between the vertex satellite and the space vectors corresponding to other satellites, search for the satellite set corresponding to the vertex satellite that satisfies the construction of the other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center;

[0046] Step 4, sort the bottom vertex satellite set corresponding to each satellite in descending order of the number of satellites;

[0047] Step 5, sequentially selecting three satellites from the bottom vertex satellite set and their corresponding vertex satellites to construct an approximate regular tetrahedron, and the four satellites constituting the approximate regular tetrahedron form an initial list of satellites to be captured;

[0048] Step 6, capture the satellites in the initial list of satellites to be captured in sequence. If the first satellite emitting a long code signal is successfully captured, proceed to step 7; if the capture of the four satellites in the initial list of satellites to be captured fails, return to step 5, reselect four satellites that form a new approximate regular tetrahedron as a new list of satellites to be captured, and continue to capture satellites in the new list of satellites to be captured until the first satellite emitting a long code signal is successfully captured;

[0049] Step 7, use the first satellite captured to calibrate the local time of the receiver, and perform parallel capture of the remaining satellites based on the local time-calibrated receiver;

[0050] Step 8: The receiver obtains observation information and ephemeris parameters in real time from the long code signals transmitted by all successfully captured satellites until the receiver achieves the first positioning and the receiver cold start is completed.

[0051] Compared with the prior art, the above-mentioned satellite navigation receiver cold start long code signal acquisition method, device and medium have the following technical effects:

[0052] 1. By establishing mathematical constraints on the angle relationship between the space vectors corresponding to the satellites transmitting long code signals, four satellites are searched among all satellites to construct an approximate regular tetrahedron with the center of the earth as the body center, and these four satellites are combined into an initial list of satellites to be captured. The list of satellites to be captured generated in this way makes at least one of the satellites visible at any position on the surface of the earth and above, and the initial list of satellites to be captured greatly compresses the search space of different satellites, without searching for satellites all over the sky, which greatly reduces the number of satellites to be searched, so that the first satellite can be captured quickly and the multi-satellite parallel capture process can be entered early.

[0053] 2. In the process of generating the list of satellites to be captured, the position distribution of all satellites transmitting long code signals and the angle of the corresponding space vectors are first calculated, and then one satellite is selected as the vertex of the approximate regular tetrahedron in turn, and the set of satellites that may form the vertex of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center is searched. After traversing all satellites, three satellites are selected from the set of bottom vertex satellites according to certain criteria, and these three satellites and the corresponding vertex satellites are used as the list of satellites to be captured. This method of searching one by one to determine the satellites in the list of satellites to be captured can more flexibly adapt to different satellite distribution situations, especially when the number of satellites in a single-constellation satellite navigation system is limited, it can more effectively find a satellite combination that forms an approximate regular tetrahedron with the vertex satellite, thereby achieving more efficient and reliable satellite capture.

[0054] 3. By calibrating the local time of the receiver using the first satellite captured in the initial list of satellites to be captured, a more accurate local time can be obtained. Due to the improved time accuracy, the code phase ambiguity during capture is significantly reduced, and the time required for capture and the hardware processing resources are greatly reduced. On this basis, the remaining satellites are captured in parallel until the cold start is completed, which can further improve the long code signal capture efficiency of the receiver during cold start.

[0055] Compared with the prior art, the present application greatly compresses the search space of different satellites for the three-dimensional search process of different satellites, carrier frequencies and code phases faced by long code signal capture by generating a minimized initial list of satellites to be captured. After the receiver is locally calibrated with the first satellite captured in the list, the remaining satellites are captured in parallel, which can effectively reduce the cold start time of the receiver and achieve rapid capture of long code signals during the cold start of the receiver. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the flow of a method for cold-starting a long code signal acquisition of a satellite navigation receiver in one embodiment;

[0057] Figure 2 A schematic diagram of a regular tetrahedron and its inscribed sphere in one embodiment;

[0058] Figure 3 A schematic diagram of redundant angle calculation in one embodiment;

[0059] Figure 4 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application 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 application and are not used to limit the present application.

[0061] In one embodiment, Figure 1 As shown, a method for cold-starting a long code signal acquisition of a satellite navigation receiver is provided, comprising the following steps:

[0062] Step 1: For a single-constellation satellite navigation system, calculate and obtain the position distribution of all satellites that transmit long code signals.

[0063] Specifically, the approximate spatial positions of all satellites transmitting long code signals are calculated based on the approximate time and the valid almanac parameters stored in the receiver. The validity period of the almanac parameters can be more than half a year.

[0064] Step 2: Calculate and obtain the angle between the space vectors corresponding to any two satellites.

[0065] Specifically, in the Earth-centered Earth-fixed (ECEF) coordinate system, the space vector corresponding to the satellite is obtained according to the approximate spatial position of the satellite, and the angle between the space vectors corresponding to any two satellites is calculated according to the vector angle calculation formula, which is expressed as

[0066] ;

[0067] in, and Respectively represent Satellites and Satellites The corresponding space vector is, and They are and The model, express and The angle between , ,and , Indicates the total number of satellites transmitting long code signals.

[0068] Step 3, select one satellite at a time as the vertex of the approximate regular tetrahedron, and based on the angle between the vertex satellite and the space vectors corresponding to other satellites, search for the satellite set corresponding to the vertex satellite that satisfies the construction of other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center.

[0069] Specifically, select Satellite As the vertices of the approximate regular tetrahedron, and search for vertex satellites Correspondingly, the satellite set of other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center is satisfied, and the satellite set is recorded as the bottom surface vertex satellite set ,in, The space vector corresponding to the mid-satellite and the vertex satellite The angle between the corresponding space vectors The satisfied angle range constraint is expressed as

[0070] ;

[0071] in, The angle between the vectors from each vertex to the center of the earth is the size of the angle between the vertices of the tetrahedron and the vertices of the bottom surface when the vertices of the tetrahedron and the bottom surface form a regular tetrahedron tangent to the earth. At this time, the earth is assumed to be a perfect sphere. Since the satellites in the single-constellation satellite navigation system are all medium- and high-orbit satellites, the actual distance to the center of the earth is greater than the distance from the vertex of the regular tetrahedron tangent to the earth to the center of the earth. The angle between the vectors from each vertex of the constructed approximate regular tetrahedron to the center of the earth is smaller than The size of allows a certain offset, and this angle offset is recorded as the redundant angle .

[0072] in, The calculation process is:

[0073] like Figure 2 As shown, draw the perpendicular bisector AE of the base of the regular tetrahedron through point A. The center of the regular tetrahedron and the center of the sphere are at the same position O. OE is the radius of the inscribed sphere. , AO=BO, at right angles From the Pythagorean theorem, we know that:

[0074] ;

[0075] Further simplified to:

[0076] ;

[0077] In △AOB, the cosine theorem shows that:

[0078] ;

[0079] Further joint solution can be obtained:

[0080] ;

[0081] By solving the above equation with inverse trigonometric functions, we can get the angle between the vectors from the vertices of the regular tetrahedron to the center of the body:

[0082] .

[0083] Redundancy Angle The calculation diagram is as follows Figure 3 As shown in the figure, assuming that the earth is a perfect sphere, point P is a vertex of a regular tetrahedron tangent to the earth, and M1 and P1 are two tangent points that pass through point P and are tangent to the earth. Assuming that the satellite is actually at point S, and its orbital altitude is higher than point P, the actual spherical cap area covered by the satellite's transmitted signal will be larger than the area covered when it is at point P. Therefore, when the satellite is offset from point S to point S1 by a certain angle, it can still cover the area covered when it is at point P. Here, the angle allowed for offset is called the redundant angle. Figure 3 In the expression The specific method for calculating the redundant angle is as follows:

[0084] At right angles middle, ,but for:

[0085] ;

[0086] It can be found by inverse trigonometric functions The degree of is:

[0087] ;

[0088] At right angles In the equation, given the radius of the earth M1O and the distance S1O from the satellite point S1 to the center of the earth O, then for:

[0089] ;

[0090] Similarly, we can use inverse trigonometric functions to find The degree of is:

[0091] ;

[0092] exist China, United The degree and The degree of the triangle can be measured by the exterior angle Calculate :

[0093] ;

[0094] The redundancy angle calculated above Only the redundant angle of a single satellite is considered, but in reality, satellites are redundant with each other. Therefore, relative to a certain satellite as a vertex, the redundant angle of the satellites at other vertices of the bottom surface to be searched is for:

[0095] .

[0096] Step 4: Sort the bottom vertex satellite set corresponding to each satellite in descending order of the number of satellites.

[0097] Specifically, the bottom vertex satellite set corresponding to each vertex satellite is sorted in descending order of the number of satellites to obtain the bottom vertex satellite set sequence, which is expressed as ;in, is the total number of satellites transmitting long code signals, Indicates The satellite set of the bottom vertex, express The satellites, for The total number of satellites in , Indicates n The satellite set of the bottom vertex The total number of satellites in .

[0098] Step 5, sequentially select three satellites from the bottom vertex satellite set and construct an approximate regular tetrahedron with their corresponding vertex satellites, and form an initial list of satellites to be captured with the four satellites constituting the approximate regular tetrahedron.

[0099] Specifically, the satellite sets at the bottom vertices are arranged in order. Select three satellites that approximately form an equilateral triangle, and construct an approximate regular tetrahedron based on these three satellites and their corresponding vertex satellites; the selection rule of the three satellite combination G that approximately forms an equilateral triangle is:

[0100] Satellite collection at the bottom vertex Select the j Satellites As the first satellite in satellite group G, and Search and satellite The angle between the corresponding space vectors is Satellite collection within the interval , if the satellite collection Does not exist or the subsequent step is in the satellite collection If the second or third satellite of satellite combination G cannot be selected, update j=j+1 and repeat the step; j The initial value of ; Represents a satellite collection The l satellites;

[0101] Meet at Satellite Select the p Satellites As the second satellite in satellite group G, and in satellite group Search and satellite The angle between the corresponding space vectors is Satellite collection within the interval , if the satellite collection If it does not exist, update p=p+1 and repeat the step; where, p The initial value of ; Represents a satellite collection The k satellites;

[0102] If the satellites gather If exists, then in the satellite set Select any satellite as the third satellite in the satellite combination G, and combine the three satellites in the satellite combination G and their corresponding vertex satellites to form an initial list of satellites to be captured.

[0103] The above steps 1 to 5 provide a method for generating an initial list of satellites to be captured. This method establishes mathematical constraints on the angle relationship between the space vectors corresponding to the satellites transmitting long code signals, searches for four satellites among all satellites to construct an approximate regular tetrahedron with the center of the earth as the body center, and forms the initial list of satellites to be captured. The list of satellites to be captured generated in this way makes at least one of the satellites visible at any position on the surface of the earth and above, and the initial list of satellites to be captured greatly compresses the search space of different satellites, and there is no need to search for satellites all over the sky, which greatly reduces the number of satellites to be searched, so that the first satellite can be captured quickly and the multi-satellite parallel capture process can be entered early.

[0104] In the process of generating the list of satellites to be captured, the position distribution of all satellites transmitting long code signals and the angle of the corresponding space vectors are first calculated, and then one satellite is selected as the vertex of the approximate regular tetrahedron in turn, and the set of satellites that may form the vertex of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center is searched. After traversing all satellites, three satellites are selected from the set of bottom vertex satellites according to certain criteria, and these three satellites and the corresponding vertex satellites are used as the list of satellites to be captured. This method of searching one by one to determine the satellites in the list of satellites to be captured can more flexibly adapt to different satellite distribution situations, especially when the number of satellites in a single-constellation satellite navigation system is limited, it can more effectively find a satellite combination that forms an approximate regular tetrahedron with the vertex satellite, thereby achieving more efficient and reliable satellite capture.

[0105] Step 6, capture the satellites in the initial list of satellites to be captured in sequence. If the first satellite emitting a long code signal is successfully captured, proceed to step 7; if the capture of the four satellites in the initial list of satellites to be captured fails, return to step 5, reselect four satellites that form a new approximate regular tetrahedron as a new list of satellites to be captured, and continue to capture satellites in the new list of satellites to be captured until the first satellite emitting a long code signal is successfully captured.

[0106] Step 7: Use the first satellite captured to calibrate the local time of the receiver, and then perform parallel capture of the remaining satellites based on the local time-calibrated receiver.

[0107] Specifically, the local time of the receiver is calibrated using the single-satellite calibration method using the first captured satellite that transmits a long code signal, and the remaining satellites are captured in parallel based on the local time-calibrated receiver. During the parallel capture process, some invisible stars are eliminated based on the angle relationship between the space vectors corresponding to the remaining satellites and the first captured satellite, thereby further narrowing the satellite capture range.

[0108] Among them, the receiver local time is calibrated using the first satellite captured in the initial list of satellites to be captured, which can obtain a more accurate local time. Due to the improved time accuracy, the receiver can be more accurately synchronized with the clock of the satellite signal. This means that when capturing the signal, the phase information can correspond more accurately to the real satellite signal, thereby reducing the uncertainty in the phase solution process, significantly reducing the code phase ambiguity during signal capture, and greatly reducing the time required for capture and hardware processing resources. On this basis, the remaining satellites are captured in parallel until the cold start is completed, which can further improve the receiver's long code signal capture efficiency during cold start.

[0109] Step 8: The receiver obtains observation information and ephemeris parameters in real time from the long code signals transmitted by all successfully captured satellites until the receiver achieves the first positioning and the receiver cold start is completed.

[0110] Compared with the prior art, the present application provides a method for cold-starting long code signal capture of a satellite navigation receiver. For the three-dimensional search process faced by long code signal capture, such as different satellites, carrier frequencies and code phases, the search space of different satellites is greatly compressed by generating a minimized initial list of satellites to be captured. After the receiver is locally calibrated with the first satellite captured in the list, the remaining satellites are captured in parallel, which can effectively reduce the cold-start time of the receiver and realize the rapid capture of long code signals during the cold-start of the receiver.

[0111] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 4As shown. The computer device includes a processor, a memory, a network interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for cold-starting long code signal capture of a satellite navigation receiver is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0112] Those skilled in the art will understand that Figure 4 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0113] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0114] Step 1: For a single-constellation satellite navigation system, calculate and obtain the position distribution of all satellites that transmit long code signals;

[0115] Step 2, calculate and obtain the angle between the space vectors corresponding to any two satellites;

[0116] Step 3, select one satellite in turn as the vertex of the approximate regular tetrahedron, and according to the angle between the vertex satellite and the space vectors corresponding to other satellites, search for the satellite set corresponding to the vertex satellite that satisfies the construction of the other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center;

[0117] Step 4, sort the bottom vertex satellite set corresponding to each satellite in descending order of the number of satellites;

[0118] Step 5, sequentially selecting three satellites from the bottom vertex satellite set and their corresponding vertex satellites to construct an approximate regular tetrahedron, and the four satellites constituting the approximate regular tetrahedron form an initial list of satellites to be captured;

[0119] Step 6, capture the satellites in the initial list of satellites to be captured in sequence. If the first satellite emitting a long code signal is successfully captured, proceed to step 7; if the capture of the four satellites in the initial list of satellites to be captured fails, return to step 5, reselect four satellites that form a new approximate regular tetrahedron as a new list of satellites to be captured, and continue to capture satellites in the new list of satellites to be captured until the first satellite emitting a long code signal is successfully captured;

[0120] Step 7, use the first satellite captured to calibrate the local time of the receiver, and perform parallel capture of the remaining satellites based on the local time-calibrated receiver;

[0121] Step 8: The receiver obtains observation information and ephemeris parameters in real time from the long code signals transmitted by all successfully captured satellites until the receiver achieves the first positioning and the receiver cold start is completed.

[0122] In one embodiment, a computer readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0123] Step 1: For a single-constellation satellite navigation system, calculate and obtain the position distribution of all satellites that transmit long code signals;

[0124] Step 2, calculate and obtain the angle between the space vectors corresponding to any two satellites;

[0125] Step 3, select one satellite in turn as the vertex of the approximate regular tetrahedron, and according to the angle between the vertex satellite and the space vectors corresponding to other satellites, search for the satellite set corresponding to the vertex satellite that satisfies the construction of the other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center;

[0126] Step 4, sort the bottom vertex satellite set corresponding to each satellite in descending order of the number of satellites;

[0127] Step 5, sequentially selecting three satellites from the bottom vertex satellite set and their corresponding vertex satellites to construct an approximate regular tetrahedron, and the four satellites constituting the approximate regular tetrahedron form an initial list of satellites to be captured;

[0128] Step 6, capture the satellites in the initial list of satellites to be captured in sequence. If the first satellite emitting a long code signal is successfully captured, proceed to step 7; if the capture of the four satellites in the initial list of satellites to be captured fails, return to step 5, reselect four satellites that form a new approximate regular tetrahedron as a new list of satellites to be captured, and continue to capture satellites in the new list of satellites to be captured until the first satellite emitting a long code signal is successfully captured;

[0129] Step 7, use the first satellite captured to calibrate the local time of the receiver, and perform parallel capture of the remaining satellites based on the local time-calibrated receiver;

[0130] Step 8: The receiver obtains observation information and ephemeris parameters in real time from the long code signals transmitted by all successfully captured satellites until the receiver achieves the first positioning and the receiver cold start is completed.

[0131] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0132] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0133] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for cold-starting long code signal acquisition of a satellite navigation receiver, characterized in that: The method comprises: Step 1: For a single-constellation satellite navigation system, calculate and obtain the position distribution of all satellites that transmit long code signals; Step 2, calculate and obtain the angle between the space vectors corresponding to any two satellites; Step 3, select one satellite in turn as the vertex of the approximate regular tetrahedron, and according to the angle between the vertex satellite and the space vectors corresponding to other satellites, search for the satellite set corresponding to the vertex satellite that satisfies the construction of the other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center; Step 4, sort the bottom vertex satellite set corresponding to each satellite in descending order of the number of satellites; Step 5, sequentially selecting three satellites from the bottom vertex satellite set and their corresponding vertex satellites to construct an approximate regular tetrahedron, and the four satellites constituting the approximate regular tetrahedron form an initial list of satellites to be captured; Step 6, capturing the satellites in the initial list of satellites to be captured in sequence. If the first satellite emitting a long code signal is successfully captured, proceed to step 7; if the four satellites in the initial list of satellites to be captured fail to be captured, return to step 5, reselect four satellites forming a new approximate regular tetrahedron as a new list of satellites to be captured, and continue to capture satellites in the new list of satellites to be captured until the first satellite emitting a long code signal is successfully captured; Step 7, use the first satellite captured to calibrate the local time of the receiver, and perform parallel capture of the remaining satellites based on the local time-calibrated receiver; Step 8: The receiver obtains observation information and ephemeris parameters in real time from the long code signals transmitted by all successfully captured satellites until the receiver achieves the first positioning and the receiver cold start is completed.

2. The method according to claim 1, characterized in that: For a single-constellation satellite navigation system, calculate and obtain the position distribution of all satellites transmitting long code signals, including: For single-constellation satellite navigation systems, the approximate spatial positions of all satellites transmitting long code signals are calculated based on the approximate time and the valid almanac parameters saved by the receiver.

3. The method according to claim 2, characterized in that Calculate the angle between the space vectors corresponding to any two satellites, including: In the Earth-centered Earth-fixed coordinate system, the space vector corresponding to the satellite is obtained according to the approximate spatial position of the satellite, and the angle between the space vectors corresponding to any two satellites is calculated according to the vector angle calculation formula, which is expressed as ； in, and Respectively represent Satellites and Satellites The corresponding space vector is, and They are and The model, express and The angle between , ,and , Indicates the total number of satellites transmitting long code signals.

4. The method according to claim 3, characterized in that Select one satellite in turn as the vertex of the approximate regular tetrahedron, and according to the angle between the space vectors corresponding to the vertex satellite and other satellites, search for the satellite set corresponding to the vertex satellite that satisfies the construction of the other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center, including: Select Satellite As the vertices of the approximate regular tetrahedron, and search for vertex satellites Correspondingly, the satellite set of other vertices of the bottom surface of the approximate regular tetrahedron with the center of the earth as the body center is satisfied, and the satellite set is recorded as the bottom surface vertex satellite set ,in, The space vector corresponding to the mid-satellite and the vertex satellite The angle between the corresponding space vectors The satisfied angle range constraint is expressed as ； in, The angle between the vectors from each vertex to the center of the earth is the size of the angle between the vertices of the tetrahedron and the vertices of the bottom surface when the vertices of the tetrahedron and the bottom surface form a regular tetrahedron tangent to the earth. At this time, the earth is assumed to be a perfect sphere. Since the satellites in the single-constellation satellite navigation system are all medium- and high-orbit satellites, the actual distance to the center of the earth is greater than the distance from the vertex of the regular tetrahedron tangent to the earth to the center of the earth. The angle between the vectors from each vertex of the constructed approximate regular tetrahedron to the center of the earth is smaller than The size of allows a certain offset, and this angle offset is recorded as the redundant angle .

5. The method according to claim 4, characterized in that Sort the bottom vertex satellite sets corresponding to each satellite in descending order of the number of satellites, including: According to the order of satellite numbers from large to small, the bottom vertex satellite sets corresponding to each vertex satellite are sorted to obtain the bottom vertex satellite set sequence, which is expressed as ;in, is the total number of satellites transmitting long code signals, Indicates The satellite set of the bottom vertex, express The satellites, for The total number of satellites in , Indicates n The satellite set of the bottom vertex The total number of satellites in .

6. The method according to claim 5, characterized in that Sequentially select three satellites from the bottom vertex satellite set and construct an approximate regular tetrahedron with their corresponding vertex satellites, and form an initial list of satellites to be captured with the four satellites constituting the approximate regular tetrahedron, including: The satellites are assembled in order at the bottom vertices Select three satellites that approximately form an equilateral triangle, and construct an approximate regular tetrahedron based on these three satellites and their corresponding vertex satellites; the selection rule of the three satellite combination G that approximately forms an equilateral triangle is: Satellite collection at the bottom vertex Select the j Satellites As the first satellite in satellite group G, and Search and satellite The angle between the corresponding space vectors is Satellite collection within the interval , if the satellite collection Does not exist or the subsequent step is in the satellite collection If the second or third satellite of satellite combination G cannot be selected, update j=j+1 and repeat the step; j The initial value of ; Represents a satellite collection The l satellites; Meet at Satellite Select the p Satellites As the second satellite in satellite group G, and in satellite group Search and satellite The angle between the corresponding space vectors is Satellite collection within the interval , if the satellite collection If it does not exist, update p=p+1 and repeat the step; where, p The initial value of ; Represents a satellite collection The k satellites; If the satellites gather If exists, then in the satellite set Select any satellite as the third satellite in the satellite combination G, and combine the three satellites in the satellite combination G and their corresponding vertex satellites to form an initial list of satellites to be captured.

7. The method according to claim 6, characterized in that The local time of the receiver is calibrated using the first satellite captured, and the remaining satellites are captured in parallel based on the local time-calibrated receiver, including: The single-satellite calibration method is used to calibrate the local time of the receiver using the first captured satellite that transmits a long code signal, and the remaining satellites are captured in parallel based on the local time-calibrated receiver. During the parallel capture process, some invisible stars are eliminated based on the angle relationship between the space vectors corresponding to the remaining satellites and the first captured satellite, thereby further narrowing the satellite capture range.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

Images