Low-cost Beidou satellite positioning enhancement method

Abstract

The invention relates to a low-cost Beidou satellite positioning enhancement method, and belongs to the technical field of GNSS positioning. According to the invention, the first Beidou terminal receives the correction number information, realizes high-precision positioning and obtains the observation value domain difference correction number of the position where the first Beidou terminal is located, and at the moment, the first Beidou terminal is used as a base station to establish a Beidou short message multicast group with other Beidou terminals; and broadcasting the observation value domain difference correction number to other Beidou terminals in the area through Beidou short message broadcasting. According to the invention, cooperative positioning of a plurality of north hopper terminals in a working area can be realized without relying on a ground base station; and communication resources of a Beidou No.3 global satellite navigation system are fully utilized, satellite-based and ground-based differential correction number broadcasting is realized based on Beidou short messages, and high-precision positioning and communication self-closed-loop of the system can be realized only through a Beidou system. Infrastructure construction investment is reduced to the maximum extent, the service coverage range is wide, cost is low, and the system is light and easy to deploy.

Description

Technical Field

[0001] The present invention belongs to the technical field of GNSS positioning, and particularly relates to a low-cost Beidou satellite positioning enhancement method. Background Technique

[0002] The Global Navigation Satellite System (GNSS) generally refers to all satellite navigation systems, including global, regional, and enhanced satellite navigation systems.

[0003] Satellite positioning enhancement systems are mainly divided into two categories: space-based augmentation systems (SBAS) and ground-based augmentation systems (GBAS). Space-based augmentation systems such as the Wide Area Augmentation System (WAAS) in the United States and the Differential Correction and Monitoring System (SDCM) in Russia, and ground-based augmentation systems such as the Local Area Augmentation System (LAAS) in the United States. These systems comprehensively use different navigation enhancement technologies to ultimately achieve the purpose of improving the performance of satellite navigation services. The satellite navigation enhancement technologies used in these enhancement systems mainly include accuracy enhancement technology, integrity enhancement technology, continuity and availability enhancement technology. Among them, the accuracy enhancement technology mainly uses the differential principle and can be further divided into wide area differential technology, local area differential technology, wide area precise positioning technology, and local area precise positioning technology. The corresponding technical directions include network RTK, PPP / PPP-RTK / PPP-AR, etc. PPP / PPP-RTK / PPP-AR decomposes the "observation value error" of the reference station into "state quantity errors" such as satellite orbit, satellite clock error, satellite phase deviation, ionospheric delay, and tropospheric delay through state domain modeling. PPP / PPP-RTK / PPP-AR is called State Space Representation (SSR), and network RTK is called Observation Space Representation (OSR).

[0004] Information of Similar Products:

[0005] Patent for Invention: Space-ground integrated PPP-RTK precise positioning service method and system for communication base station planning; Publication Number (Publication): CN117471511A

[0006] The invention provides a space-ground integrated PPP-RTK precise positioning service method and system for communication base station planning, including that a data processing center receives the real-time observation value data stream broadcast by a reference station network, and uses a non-ionospheric combined network solution method to calculate the real-time state domain enhanced product; further extracts the fixed solution ionospheric delay and tropospheric delay by using a non-differential and non-combined precise point positioning model to obtain an atmospheric delay product; takes the communication base station as a virtual station to obtain a virtual observation value OSR product; under the condition of no support from the ground communication network, receives the SSR product broadcast by satellites, and uses the PPP-RTK positioning mode to achieve high-precision positioning, or generates a virtual observation value OSR product at the approximate position of the user by using the SSR product for RTK positioning; under the condition of support from the ground communication network, receives the virtual observation value OSR product of the corresponding access point base station, and uses the network RTK positioning mode to achieve high-precision positioning.

[0007] In the prior art, the ground-based augmentation system needs to rely on a large number of ground reference stations to calculate the observation value domain differential correction number, and the space-based augmentation system calculates correction products such as satellite orbits, clock errors, code biases, phase biases, ionospheric and tropospheric delays. Although service broadcast can be achieved based on the ground communication network, it is difficult to meet the requirements of typical scenarios such as remote areas or offshore navigation. Summary of the Invention

[0008] (1) Technical Problems to be Solved

[0009] The technical problem to be solved by the present invention is how to provide a low-cost Beidou satellite positioning enhancement method to solve the problems that in the prior art, the ground-based augmentation system needs to rely on a large number of ground reference stations to calculate the observation value domain differential correction number, the space-based augmentation system calculates correction products such as satellite orbits, clock errors, code biases, phase biases, ionospheric and tropospheric delays, and although service broadcast can be achieved based on the ground communication network, it is difficult to meet the requirements of typical scenarios such as remote areas or offshore navigation.

[0010] (2) Technical Solutions

[0011] To solve the above technical problems, the present invention proposes a low-cost Beidou satellite positioning enhancement method, which includes the following steps:

[0012] S1. Build a certain number of ground-based augmentation reference stations with known coordinates in the service area, conduct a mesh coverage of the service area to form a ground-based augmentation station network;

[0013] S2. Check the integrity of the observation data of each reference station, calculate the state domain differential correction number, that is, calculate the PPP-AR correction number, and push the correction number to the high-precision service center;

[0014] S3. The high-precision service center encodes the correction number according to a specific correction number encoding strategy;

[0015] S4. Multiple Beidou terminals are deployed in an operating area. The first Beidou terminal initiates a positioning request to the high-precision service center through a Beidou short message. The high-precision service center receives the request from the first Beidou terminal and sends the PPP-AR correction number to the first Beidou terminal through a Beidou short message.

[0016] S5. The first Beidou terminal receives the correction information, realizes high-precision positioning, and obtains the observation domain differential correction of the location, that is, solves the RTK correction. At this time, the terminal acts as a reference station and establishes a Beidou short message multicast group with other Beidou terminals, and broadcasts the observation domain differential correction to other Beidou terminals in the area through Beidou short message broadcast;

[0017] S6. Other Beidou terminals receive the differential correction numbers sent by the first Beidou terminal to achieve high-precision solutions.

[0018] (III) Beneficial effects

[0019] The present invention proposes a low-cost Beidou satellite positioning enhancement method. Compared with the prior art, the Beidou satellite positioning enhancement method proposed by the present invention can realize the coordinated positioning of multiple Beidou terminals in the operating area without relying on the ground reference station; and fully utilizes the communication resources of the Beidou-3 global satellite navigation system, realizes the broadcast of satellite-based and ground-based differential correction numbers based on Beidou short messages, and can realize high-precision positioning of the system and self-closed communication loop only through the Beidou system. The present invention minimizes the investment in infrastructure construction, has a wide service coverage, and is low-cost, lightweight and easy to deploy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of PPP-AR correction number calculation of the present invention;

[0021] Figure 2 Format diagram for satellite orbit correction information type 1;

[0022] Figure 3 Satellite clock correction information type 2 format layout diagram;

[0023] Figure 4 The satellite code deviation information type 3 format is arranged in diagram;

[0024] Figure 5 Format diagram for satellite phase deviation information type 4;

[0025] Figure 6 This is the flow chart of the interaction between Beidou terminal and service center. DETAILED DESCRIPTION

[0026] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0027] The patent of this invention belongs to the field of GNSS positioning technology. It mainly optimizes the Beidou satellite positioning enhancement method to ensure the high-precision positioning accuracy and efficiency of Beidou terminals, reduce the scale of ground-based enhanced ground station infrastructure construction, and expand the coverage of Beidou high-precision services. The present invention particularly relates to a low-cost Beidou satellite positioning enhancement method and system without base station reliance and external communication resource dependence.

[0028] The patent of this invention aims to solve the above-mentioned technical problems and provide a Beidou satellite positioning enhancement method that does not rely on a base station or external communication resources during operation. It combines multiple high-precision positioning modes such as network RTK and PPP-AR to achieve multi-terminal collaborative positioning and improve the positioning performance of a group of Beidou terminals in the coverage area. It makes full use of the resources of the Beidou-3 global satellite navigation system and realizes high-precision service broadcasting through Beidou short messages. The high-precision service range can cover the Asia-Pacific region.

[0029] The present invention provides a low-cost Beidou satellite positioning enhancement method and system, in particular, a low-cost Beidou satellite positioning enhancement method and system without relying on a reference station or external communication resources, the method comprising:

[0030] S1. Build a certain number of ground-based augmentation reference stations with known coordinates in the service area to provide mesh coverage of the service area and form a ground-based augmentation station network;

[0031] S2. Check the integrity of the observation data of each base station, calculate the state domain differential correction, that is, calculate the PPP-AR correction, and push the correction to the high-precision service center;

[0032] S3, the high-precision service center performs correction number encoding according to a specific correction number encoding strategy;

[0033] S4. Multiple Beidou terminals (user stations) are deployed in an operating area. The first Beidou terminal (station A) initiates a positioning request to the high-precision service center through a Beidou short message. The high-precision service center receives the request from the first Beidou terminal and sends the PPP-AR correction number to the first Beidou terminal through a Beidou short message.

[0034] S5. The first Beidou terminal receives the correction information, realizes high-precision positioning, obtains the observation value domain differential correction of the location, that is, solves the RTK correction. At this time, the terminal acts as a reference station, establishes a Beidou short message multicast group with other Beidou terminals, and broadcasts the observation value domain differential correction to other Beidou terminals in the area (station B, station C, ..., station N) through Beidou short message broadcast;

[0035] S6. Other Beidou terminals receive the differential correction numbers sent by the first Beidou terminal's A station to achieve high-precision solution calculation.

[0036] Embodiment 1:

[0037] Another technical solution of the present invention is based on the above. In step S1, within the service area, a ground-based augmentation reference station is built. Specifically, during construction, since this system only needs to broadcast PPP-AR correction numbers through the Beidou high-precision service center, the required data of the ground-based augmentation stations is less. Only 70 ground-based augmentation stations are needed to cover the whole country in the Asia-Pacific region.

[0038] Another technical solution of the present invention is based on the above. In step S2, the observation data of each reference station is preprocessed by real-time reception and integrity check, etc. The state-domain differential correction numbers are estimated by methods such as non-differential and non-combination. The correction numbers include four categories: precise orbit, precise clock error, differential code bias (DCB), and uncalibrated phase hardware delay (UPD). The processing flow is as Figure 1 shown. And the correction numbers are pushed to the high-precision service center. The high-precision service center is the Beidou satellite positioning augmentation service processing center, which converges the GNSS reference station observation data and has the ability to solve the Beidou satellite positioning augmentation service.

[0039] Another technical solution of the present invention is based on the above. In step S3, the high-precision service center designs a specific correction number encoding according to the Beidou short message communication ability. The Beidou short message communication levels are divided into level 1 to level 5, and the supported broadcast telegram lengths are 692 bit, 1835 bit, 3883 bit, 7979 bit, and 14000 bit respectively. The Beidou short message broadcast frequency supports 15 levels, including: 1s, 2s, 3s, 5s, 6s, 8s, 10s, 20s, 30s, 40s, 50s, 1min, 2min, 5min, 15min.

[0040] The basic data frame structure of the Beidou short message PPP-AR navigation augmentation telegram refers to the RTCM standard definition as Figure 2 shown, which includes three parts: a data header, telegram content, and a data tail. The data header consists of an 8-bit leading bit and a 12-bit telegram length. The data tail consists of 24-bit cyclic redundancy check bits (CRC). The remaining bits are the telegram content, which is mainly divided into a telegram header and a data body. The Beidou short message PPP-AR navigation augmentation telegram mainly includes satellite orbit correction information, satellite clock error correction information, satellite code deviation information, and phase deviation information.

[0041] The CRC check is performed bit by bit and is calculated for the message header and data body message content. The message header is used to distinguish the information content of the valid data body. The defined information types are shown in Table 1, which specifically include information type 1: satellite orbit correction information, information type 2: satellite clock correction information, information type 3: satellite code deviation information, information type 4: satellite phase deviation information, and the remaining information types are reserved.

[0042] Table 1 Information type definition

[0043]

[0044]

[0045] For each type of information, the message format needs to be arranged according to the characteristics of Beidou short message communication resources. The format of satellite orbit correction information message is as follows: Figure 2 As shown in the figure, the satellite clock correction information message is arranged as follows Figure 3 As shown, the satellite code deviation information message is arranged as follows Figure 4 As shown, the satellite phase deviation information message is arranged as follows Figure 5 shown.

[0046] Another technical solution of the present invention is that on this basis, in step S4, multiple Beidou terminals (user stations) in an operating area need to perform high-precision solutions. The first Beidou terminal (station A) initiates a positioning request to the high-precision service center through a Beidou short message. The high-precision service center receives the Beidou terminal request and sends the PPP-AR correction number to the Beidou terminal through a Beidou short message.

[0047] Another technical scheme of the present invention is that on this basis, in step S5, the first Beidou terminal receives PPP-AR correction number information, realizes high-precision positioning, and obtains the observation value domain differential correction number (RTK service message, meets RTK positioning solution) of the position. The terminal is used as a reference station, and a Beidou short message multicast group is established with other Beidou terminals. The baseline distance between each Beidou terminal can reach 20 kilometers, and the multicast group supports the number of terminals to reach 500. The observation value domain differential correction number is broadcasted to other Beidou terminals (B station, C station, ..., N station) in the region by Beidou short message broadcasting, and the observation value domain differential correction number also needs to be encoded according to the Beidou short message communication resource characteristics.

[0048] The RTK service message mainly contains the base station location information and Beidou satellite observation information. The differential correction number is coded and optimized to minimize the communication traffic consumption. The base station location information message design is shown in Table 2. Differential correction number coding optimization design.

[0049] Table 2 Observation range differential correction message design

[0050]

[0051]

[0052] Note: Ns represents the number of satellites; n is the number of padding digits.

[0053] In step S6, other Beidou terminals receive the observed value domain differential correction number sent by the first Beidou terminal based on Beidou short message, and achieve high-precision solution through the RTK algorithm, and smooth the positioning result. The specific steps are as follows.

[0054] S61. Other Beidou terminals obtain the positioning result data packet solved by the first Beidou terminal.

[0055] S62. Analyze the data packet, judge whether the result is the positioning position result, and classify the information.

[0056] S63. After obtaining the positioning data, make an accuracy judgment. If the accuracy exceeds the limit, do not process and return to step S61.

[0057] S64. If the accuracy requirement is met, perform data filtering and smoothing processing to obtain a relatively stable positioning result.

[0058] S65. According to the user settings, reorganize the positioning result in the CGCS2000 coordinate system after filtering processing, retain the key information, encapsulate the data according to the sending protocol, and send back the high-precision positioning result through Beidou short message.

[0059] The data interaction process between the Beidou terminal and the service center in steps S4 - S6 is as Figure 6 shown

[0060] Compared with the prior art, the Beidou satellite positioning enhancement method proposed by the present invention can realize the collaborative positioning of multiple Beidou terminals in the working area without relying on a ground reference station; and make full use of the communication resources of the Beidou-3 global satellite navigation system, and realize the broadcast of satellite-based and ground-based differential correction numbers based on Beidou short message, and can realize the high-precision positioning and communication self-closed loop of the system only through the Beidou system. The present invention minimizes the investment in infrastructure construction, has a wide service coverage range, and has low cost, is lightweight and easy to deploy.

[0061] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can still be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A low-cost Beidou satellite positioning enhancement method, characterized in that: The method comprises the following steps: S1. Build a certain number of ground-based augmentation reference stations with known coordinates in the service area to provide mesh coverage of the service area and form a ground-based augmentation station network; S2. Check the integrity of the observation data of each base station, calculate the state domain differential correction, that is, calculate the PPP-AR correction, and push the correction to the high-precision service center; S3, the high-precision service center performs correction number encoding according to a specific correction number encoding strategy; S4. Multiple Beidou terminals are deployed in an operating area. The first Beidou terminal initiates a positioning request to the high-precision service center through a Beidou short message. The high-precision service center receives the request from the first Beidou terminal and sends the PPP-AR correction number to the first Beidou terminal through a Beidou short message. S5. The first Beidou terminal receives the correction information, realizes high-precision positioning, and obtains the observation domain differential correction of the location, that is, solves the RTK correction. At this time, the terminal acts as a reference station and establishes a Beidou short message multicast group with other Beidou terminals, and broadcasts the observation domain differential correction to other Beidou terminals in the area through Beidou short message broadcast; S6. Other Beidou terminals receive the differential correction numbers sent by the first Beidou terminal to achieve high-precision solutions.

2. The low-cost Beidou satellite positioning enhancement method as claimed in claim 1, characterized in that: In S1, a ground-based augmentation base station is constructed within the service area. During the specific construction, since the system only needs to broadcast PPP-AR correction numbers through the Beidou high-precision service center, the required ground-based augmentation station data is relatively small, and only 70 ground-based augmentation stations are needed to cover the entire Asia-Pacific region.

3. The low-cost Beidou satellite positioning enhancement method as claimed in claim 1, characterized in that: In S2, the observation data of each reference station is received in real time and pre-processed with an integrity check, the state domain differential correction number is estimated by a non-difference and non-combination method, and the correction number is pushed to the high-precision service center. The high-precision service center is a Beidou satellite positioning enhancement service processing center, which aggregates GNSS reference station observation data and has the Beidou satellite positioning enhancement service solution capability.

4. The low-cost Beidou satellite positioning enhancement method as claimed in claim 3, characterized in that: The correction numbers include four categories: precise orbit, precise clock error, differential code deviation DCB, and uncalibrated phase hardware delay UPD.

5. The low-cost Beidou satellite positioning enhancement method as claimed in claim 1, characterized in that: In S3, the high-precision service center designs specific correction number coding according to the Beidou short message communication capability. The Beidou short message communication level is divided into level 1 to level 5, and can support broadcast message lengths of 692 bits, 1835 bits, 3883 bits, 7979 bits, and 14000 bits respectively. The Beidou short message broadcast frequency supports 15 levels, including: 1s, 2s, 3s, 5s, 6s, 8s, 10s, 20s, 30s, 40s, 50s, 1min, 2min, 5min, and 15min.

6. The low-cost Beidou satellite positioning enhancement method as claimed in claim 5, characterized in that: The PPP-AR navigation enhancement message data frame structure of the Beidou short message includes three parts: a data header, a message content and a data tail. The data header consists of an 8-bit leading bit and a 12-bit message length, and the data tail consists of 24 bits for cyclic redundancy check bits; the remaining bits are the message content, which is divided into a message header and a data body. The Beidou short message PPP-AR navigation enhancement message includes satellite orbit correction information, satellite clock correction information, satellite code deviation information, and phase deviation information; CRC check is performed bit by bit, and is calculated for the message header and data body message content; the message header is used to distinguish the information content broadcast by the valid data body; The defined information types include: information type 1: satellite orbit correction information, information type 2: satellite clock correction information, information type 3: satellite code deviation information, information type 4: satellite phase deviation information, and the remaining information types are reserved; For each type of information, the message format needs to be arranged according to the characteristics of Beidou short message communication resources.

7. The low-cost Beidou satellite positioning enhancement method according to any one of claims 1 to 6, characterized in that: In S4, multiple Beidou terminals in an operating area need to perform high-precision solutions. The first Beidou terminal initiates a positioning request to the high-precision service center through a Beidou short message. The high-precision service center receives the Beidou terminal request and sends the PPP-AR correction number to the Beidou terminal through a Beidou short message.

8. The low-cost Beidou satellite positioning enhancement method as claimed in claim 7, characterized in that: In S5, the first Beidou terminal receives the PPP-AR correction information to achieve high-precision positioning, thereby obtaining the observation value domain differential correction number of the location; the terminal is used as a reference station to establish a Beidou short message multicast group with other Beidou terminals. The baseline distance between each Beidou terminal can reach 20 kilometers, and the multicast group supports up to 500 terminals; the observation value domain differential correction number is broadcast to other Beidou terminals in the area through Beidou short message broadcast, and the observation value domain differential correction number also needs to be encoded according to the characteristics of Beidou short message communication resources.

9. The low-cost Beidou satellite positioning enhancement method as claimed in claim 8, characterized in that: In S6, other Beidou terminals receive the observation domain differential correction numbers sent by the first Beidou terminal based on the Beidou short message, achieve high-precision solution through the RTK algorithm, and smooth the positioning results.

10. The low-cost Beidou satellite positioning enhancement method according to claim 9, characterized in that: The S6 specifically includes: S61, other Beidou terminals obtain the positioning result data packet solved by the first Beidou terminal; S62, parsing the data packet, determining whether the result is a positioning result, and classifying the information; S63, after obtaining the positioning data, make an accuracy judgment, if the accuracy exceeds the limit, do not process and return to step S61; S64: If the accuracy requirement is met, data filtering and smoothing are performed to obtain a relatively stable positioning result; S65. According to user settings, the positioning results in the CGCS2000 coordinate system after filtering are reorganized, key information is retained, data is encapsulated according to the sending protocol, and high-precision positioning results are transmitted back through Beidou short messages.

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