Beidou signal high-precision positioning and measuring method

Abstract

The invention belongs to the technical field of communication, and particularly relates to a Beidou signal high-precision positioning and measuring method, which comprises the following steps of: researching a mutual relation and an analytical algorithm of a Beidou signal structure, a propagation path and receiving processing, and improving the observation precision from the angle of a data source; according to a Beidou multi-frequency RTK deep coupling technology, calculating a double-difference three-frequency pseudo-range and carrier combination observation value, cooperatively applying a regional network error model, and performing coordinate calculation and error correction on the basis; and high-precision positioning data is obtained by combining precise time synchronization and a dual monitoring system. According to the invention, through a precise and efficient positioning and attitude determination algorithm, the data processing precision of Beidou signals is improved, and more accurate data support can be provided for the fields of transportation, public safety, disaster reduction and prevention and the like.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a Beidou signal high-precision positioning and measurement method. Background Art

[0002] The Beidou Navigation System (BDS) boasts short message communication capabilities unavailable in other satellite navigation systems. It boasts wide coverage, uninterrupted service around the clock, reliable and secure, and the ability to simultaneously use short message communication for navigation and positioning. This makes it a reliable backup communication method, particularly in the event of ground communication signal interruptions. Beidou boasts world-class performance indicators, including navigation and positioning, and communication data transmission. It provides global services such as positioning, navigation, and timing, global short message communication, regional short message communication, international search and rescue, satellite-based augmentation, ground-based augmentation, and precise point positioning. BDS can provide crucial data support for smart tourism, transportation, logistics, marine fisheries, public safety, disaster reduction, and prevention, and is crucial for breaking the GPS monopoly and enhancing my country's international standing.

[0003] Currently, the application and services of high-precision positioning technology are gradually expanding into mass application areas such as next-generation information technology and smart cities. With the increasing demand for intelligent, refined, and information-based management, there is an urgent need to overcome several technical bottlenecks in the algorithms, terminal systems, and industrial applications of Beidou satellite navigation precision positioning services: first, there is a lack of precise and efficient positioning algorithms, positioning terminals, and high-reliability, continuous, and precise positioning modules that collaborate with multiple sensors. Second, due to the uneven distribution of the geomagnetic field and complex conditions at base stations, the measurement results of handheld attitude detectors can have significant errors. These issues make it difficult to fully utilize the positioning and direction-finding technical advantages of BDS to obtain the precise position and attitude characteristics of monitored targets in actual applications such as geological disaster monitoring and meteorological monitoring.

[0004] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-precision positioning and measurement method for Beidou signals. In view of the problems of Beidou signal multi-peak, weak signal capture, and difficult signal processing, the corresponding improved algorithm is studied to improve the positioning and attitude determination accuracy of the detected target.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A BeiDou signal high-precision positioning and measurement method comprises the following steps:

[0008] S1. Analyze the matching relationship between Beidou signal structure, propagation and reception processing, design the CSSPCT algorithm, and perform Beidou signal multi-peak elimination, weak signal capture and tracking;

[0009] S2. Calculate the double-difference triple-frequency pseudorange and carrier combined observation values, ionospheric influence factors, and observation noise based on the pseudorange phase and carrier observation equations after correcting the troposphere, ionosphere, and antenna phase center deviations.

[0010] S3. Build a regional network error model based on multiple antennas, introduce data evaluation and constellation optimization algorithms, and perform multi-dimensional and high-precision real-time dynamic measurement of detection targets;

[0011] S4. Develop a precise synchronous acquisition mechanism for BeiDou data in complex environments to obtain high-precision relative positioning data for BeiDou monitoring points and benchmark points in complex environments;

[0012] S5. Design a dual monitoring system to obtain small changes in the position and angle of the detection target, and integrate and transmit the data.

[0013] As a preferred method, S1 uses the CSSPCT algorithm to eliminate Beidou signal multi-peaks. The principle is as follows:

[0014] Constructing shape code vectors to obtain the universal cross-correlation function expression of BOC modulation reference and derived modulation signals;

[0015] Then, a special local code waveform is designed to perform correlation operation with the corresponding received signal to obtain the signal correlation sub-function, and the sub-function is recombined using the reconstruction rule;

[0016] In addition, an additional related branch is added to the traditional tracking loop to form a three-loop structure.

[0017] As a preference, the calculation equations for the double-difference triple-frequency pseudorange and carrier combination observation values ​​in S2 are as follows:

[0018]

[0019] Preferably, a regional network error model based on multiple antennas is constructed in S3, specifically comprising the following steps:

[0020] Introducing an observation quality assessment mechanism to conduct credibility analysis on observation data from all visible satellites, prioritizing high-quality observations with high signal-to-noise ratio, few cycle slips, and small multipath errors for solution.

[0021] In terms of satellite selection strategy, an intelligent constellation optimization algorithm is used, which comprehensively considers the spatial distribution characteristics of the geometric dilution of precision (DOP) to ensure that the selected satellites have the best positioning accuracy in terms of spatial geometric configuration;

[0022] For some satellites with poor observation conditions, three-bandwidth lane combined observations are used for processing.

[0023] As a preference, S4 obtains high-precision relative positioning data of Beidou monitoring points and reference points in complex environments, which is achieved by dual-chip synchronization interface technology through two device interfaces of the monitoring station and the reference station in the region, a GPIO interface, and a baseband event input interface each; the observation moments on both sides are kept synchronized, including the following two steps: initial alignment after the chip is powered on; during subsequent operation, the observation moments of the two chips are adjusted to remain synchronized, specifically: the L1 / B1 receiver time and clock difference are corrected in real time according to the L1 / B1PVT positioning, and the information after the cumulative adjustment of 1ms is transmitted to the MeasCount value of L1 / B1 to L2 / B2, and L2 / B2 is adjusted according to the MeasCount value to keep it synchronized with L1 / B1.

[0024] As an optimal choice, the dual monitoring system designed by S5 consists of three parts: the base station, the observation station micro-area monitoring system and the background server, specifically:

[0025] The main nodes of the micro-area monitoring systems of the base station and the observation station are equipped with BDS antenna modules, BDS data processing modules and LoRa wireless communication modules, which are mainly used for displacement measurement, baseline length calculation and data exchange between the base station and the observation station main node;

[0026] The observation station micro-area monitoring system consists of a master node and multiple slave nodes. The slave nodes are equipped with BDS antenna modules, which form a baseline with the antenna module on the master node. They are used to observe data in the micro-area of ​​the observation station, integrate the data, and transmit the integrated data to the reference station through the LoRa module on the master node.

[0027] The base station is also equipped with an LTE module to send the data integrated by the base station to the background server.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The high-precision positioning and measurement method of Beidou signals of the present invention solves the problems of multiple peaks of Beidou signals and poor weak signal capture and tracking capabilities by designing the CSSPCT algorithm, significantly improves the tracking accuracy and anti-multipath performance of the signal, and is conducive to improving the signal's anti-interference performance and ranging accuracy.

[0030] (2) The high-precision positioning and measurement method of the Beidou signal of the present invention develops a regional network error model, and through the hierarchical screening of observation value quality and the optimization configuration of constellation geometry, the Beidou multi-frequency RTK strategy is collaboratively applied to achieve the best balance between computational efficiency and positioning reliability, providing a high-quality observation data foundation for real-time dynamic positioning.

[0031] (3) The high-precision positioning and measurement method of the Beidou signal of the present invention accurately calculates the integer ambiguity and attitude parameter estimation by reasonably deploying the Beidou antenna, which is beneficial to improving the positioning accuracy of the detected target and the accuracy of the motion attitude. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the method steps of the present invention;

[0033] Figure 2 This is a block diagram of the BOC signal capture principle based on correlation shift;

[0034] Figure 3 This is the workflow diagram of the three-antenna three-frequency RTK attitude determination technology;

[0035] Figure 4 This is a schematic diagram of master and slave chip synchronization;

[0036] Figure 5 It is the hardware schematic diagram of the dual monitoring system. DETAILED DESCRIPTION

[0037] The following is a clear and complete description of the technical solution of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0039] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and connections within two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0040] Refer to the attached Figure 1 A high-precision positioning and measurement method for Beidou signals includes the following steps:

[0041] S1. Analyze the matching relationship between Beidou signal structure, propagation and reception processing, design the CSSPCT algorithm, and perform Beidou signal multi-peak elimination, weak signal capture and tracking;

[0042] The system uses a dual-channel orthogonal demodulation architecture and generates two strictly orthogonal local oscillator signals through digital signal processing. These signals are divided into I and Q paths, with a phase angle difference of 90 degrees. The system uses orthogonal coherent demodulation technology to completely strip the carrier of the RF signal. After completing the carrier stripping, the system digitally modulates the baseband subcarrier signal with a pseudo-random spread spectrum sequence (PRN code) and performs spectrum convolution operations on the two through a multiplier, thereby generating a binary offset carrier (BOC) modulated signal with specific spectrum characteristics. The specific process is shown in the attached figure. Figure 2 As shown. The chip width of each pseudo-random noise (PRN) code is used as the time reference unit, and the time unit is divided into two equal subintervals. The original signal component is retained in the first subinterval, and the signal in the second subinterval is set to zero, thereby constructing the odd branch signal; correspondingly, the signal component is retained in the second subinterval and the signal in the first subinterval is set to zero, thereby forming the even branch signal. Next, in the coherent operation stage, the received satellite signal and the locally generated odd branch signal are coherently operated to obtain the initial correlation value. The correlation function is then time-shifted, delayed by half a chip period and inverted to generate a new correlation function. The new correlation function is multiplied by the original value, and the result is modulo valued. Finally, the modulus value is algebraically added to the original correlation value that has not been modulo processed. Through this special signal combination method, the secondary peak interference in the traditional correlation function is effectively eliminated, and the sharpness of the main peak signal is significantly improved.

[0043] In terms of unambiguous tracking of BOC signals, a correlation shift side-peak cancellation technique (CSSPCT) was designed. The principle is as follows: a shape code vector is constructed to obtain the universal cross-correlation function expression of the BOC modulation reference and derived modulation signals; then a special local code waveform is designed to perform correlation operations with the corresponding received signal to obtain a signal correlation sub-function, and the sub-function is recombined using reconstruction rules; in addition, an additional correlation branch is added to the traditional tracking loop to form a three-loop structure (carrier loop, subcarrier loop, code loop), which dynamically realizes unambiguous tracking of BOC signals.

[0044] S2. Calculate the double-difference triple-frequency pseudorange and carrier combined observation values, ionospheric influence factors, and observation noise based on the pseudorange phase and carrier observation equations after correcting the troposphere, ionosphere, and antenna phase center deviations.

[0045] First, the antenna phase center deviation, earth rotation effect, and tidal effect are corrected by using the model, and then the double-difference pseudo-range phase observation equation and carrier observation equation in units of distance are calculated:

[0046]

[0047] Where, is the double-difference pseudorange, is the double-difference ionospheric delay, is the double-difference ionospheric delay, is the observation noise, is the double-difference carrier observation value, η is the ionospheric factor, λ (i,j,k) is the wavelength of the combined observation value, and i, j, k, α, β, and γ are arbitrary real numbers.

[0048] The triple-frequency pseudorange combined observation value and carrier combined observation value after double difference can be expressed as equations (3) and (4) respectively:

[0049]

[0050] Where: f1, f2, f3 represent the carrier frequencies of the three frequency points B1, B2, and B3 respectively. The frequency f of the three-frequency combination observation value is (i,j,k) and wavelength λ (i,j,k) They are shown in formulas (5) and (6) respectively:

[0051] f (i,j,k) =if1+jf2+kf3 (5)

[0052] λ (i,j,k) =c / f (i,j,k) (6)

[0053] The ionospheric impact factors of the double-differenced pseudorange and carrier combined observations can be expressed as shown in equations (7) and (8), respectively:

[0054]

[0055] The observation noise of the double-differenced pseudorange and carrier combination observation values ​​can be expressed as shown in equations (9) and (10) respectively:

[0056]

[0057] S3. Build a regional network error model based on multiple antennas, introduce data evaluation and constellation optimization algorithms, and perform multi-dimensional and high-precision real-time dynamic measurement of detection targets;

[0058] For real-time kinematic positioning, data is preprocessed to reduce computational precision requirements, simplifying 8-byte floating-point calculations to 4-byte floating-point calculations, thereby improving memory and MIPS utilization. A regional network error model replaces the linear attenuation error model. Specifically, an observation quality assessment mechanism is introduced to analyze the credibility of observations from all visible satellites, prioritizing high-quality observations with high signal-to-noise ratio, low cycle slips, and minimal multipath error. Regarding satellite selection, an intelligent constellation optimization algorithm is employed, comprehensively considering the spatial distribution of the geometric dilution of precision (DOP) to ensure optimal positioning accuracy in the selected satellites' spatial geometry. For satellites with suboptimal observation conditions, three-bandwidth lane combined observations are used. Matrix operation optimization utilizes a block-based matrix calculation strategy and meticulously designs the matrix operation process. Specifically, relevant matrix operations are task-decomposed, memory allocation is pre-planned based on computational requirements, and a dynamic memory management mechanism is established to ensure orderly memory allocation, use, and release during the computation process. Specifically for key computational units like the ambiguity variance and covariance matrix, an intelligent caching mechanism is designed to enable multiple rounds of matrix data reuse while ensuring data consistency. Furthermore, attention should be paid to effectively controlling the size of the observation equations and optimizing the coefficient matrix dimensions to a reasonable range.

[0059] In terms of attitude measurement, three Beidou satellite signal receiving antennas are designed and fixed on the surface of the carrier according to certain rules. Under the premise that the three antennas can receive Beidou satellite signals, the satellite signals received by each Beidou antenna are processed to obtain carrier phase observation values ​​and code phase measurement values. The obtained measurement values ​​are combined with the least squares attitude solution algorithm to calculate the coordinates of the baseline vector between antennas in the local horizontal coordinate system, and finally the attitude of the carrier is solved through coordinate transformation. The functions and work flow of each part of the three-antenna Beidou attitude measurement receiver are shown in the attached figure. Figure 3 shown.

[0060] S4. Develop a precise synchronous acquisition mechanism for monitoring data in complex environments to obtain high-precision relative positioning data of Beidou monitoring points and benchmark points in complex environments;

[0061] Refer to the attached Figure 4 The dual-chip synchronization interface technology is implemented through two device interfaces, one GPIO interface and one baseband event input (BB_EVENT) interface for the monitoring station and the base station in the region. This interface is the physical link layer interface for raw observations or time synchronization.

[0062] When the module is powered on, the main chip monitors the slave chip interface for data frames. Once it detects that the slave chip is receiving the antenna signal and booting up, the main chip sends a signal through a GPIO to the event input interfaces of both the main and slave chips. The event interfaces of the main and slave chips simultaneously sample the input signal and generate interrupts. Internal logic and firmware work together to synchronize the input raw observations.

[0063] When an external event (BB_EVENT) occurs, both rising and falling edge triggering are supported. When a BB_EVENT is triggered, all RTC counters are latched for software access. Furthermore, a BB_EVENT trigger can generate a BB hardware interrupt, and interrupt control supports interrupt masking. These features greatly facilitate firmware development and enable fast and flexible processing of BB_EVENT transactions.

[0064] When implementing the EVENT interface, the external input signal is synchronized with the high-speed system clock. The synchronized signal is then configured to trigger on either the rising or falling edge, generating the BB_EVENT status signal. The BB_EVENT status signal serves as the external latch trigger source for the RTC module, and the interrupt mask setting determines whether a BB EVNET interrupt is generated.

[0065] Maintaining synchronization between the two observation times involves two steps: initial alignment after powering up the chips; and subsequent adjustment during operation to maintain synchronization. The L1 / B1 receiver's time and clock offset are corrected in real time based on the L1 / B1 PVT positioning. After accumulating 1ms of adjustment information, the L1 / B1 MeasCount value is transmitted to L2 / B2. L2 / B2 uses this MeasCount value to adjust its own clock to maintain synchronization with L1 / B1.

[0066] S5. Design a dual monitoring system to obtain small changes in the position and angle of the detection target, and integrate and transmit the data.

[0067] The overall structure of the dual monitoring system is as follows Figure 5As shown, the system consists of three parts: a base station, an observation station micro-area monitoring system, and a backend server. Both the base station and the master node of the observation station micro-area monitoring system are equipped with a BDS antenna module, a BDS data processing module, and a LoRa wireless communication module. These modules are primarily used for displacement measurement, baseline length calculation, and data exchange between the base station and the master node. The observation station micro-area monitoring system consists of a master node and multiple slave nodes. The slave nodes are equipped with BDS antenna modules, which form a baseline with the antenna module on the master node. This is used to observe data within the observation station micro-area monitoring system, integrate the data, and transmit it to the base station via the LoRa module on the master node. The base station is also equipped with an LTE module, which transmits the integrated data to the backend server. The backend server processes and analyzes the data sent by the base station and provides feedback to the base station, which then determines the displacement.

[0068] The hardware design principle of the BDS dual monitoring system is: the collection of target mobile data is divided into two layers and carried out simultaneously, mainly including satellite signal receiving module, data processing module, LoRa wireless transmission module, LTE wireless transmission module, background computer, etc.

[0069] The satellite receiving module uses the HP8863, the LoRa wireless transmission module uses the HC-12 wireless serial communication module, and the LTE wireless transmission module uses the USR-G7804G LTE DTU. Data collection is primarily divided into two layers: the first is data collection within the observation station's micro-area, using a wired connection, which can be later determined based on actual conditions. The second is data collection between the observation station's micro-area master node and the reference station, using LoRa wireless transmission to establish a baseline.

[0070] The software includes baseline solution in the data processing module and automatic data monitoring on the backend server. Its core component is baseline solution, based on the BDS-RTK baseline measurement principle. The raw data received by the BDS antenna module is first converted into the standard RINEX format. A double-difference observation equation is constructed based on the double-difference model. A weighted least squares method is then used to obtain a floating-point solution, which significantly improves the accuracy of the floating-point solution compared to traditional least squares estimation methods. The classic LAMBDA algorithm is then used to resolve integer ambiguities. Finally, the baseline is continuously corrected based on the integer ambiguities after baseline length validity verification.

[0071] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A high-precision positioning and measurement method for Beidou signals, characterized in that: The following steps are involved: S1. Analyze the matching relationship between Beidou signal structure, propagation and reception processing, design the CSSPCT algorithm, and perform Beidou signal multi-peak elimination, weak signal capture and tracking; S2. Calculate the double-difference triple-frequency pseudorange and carrier combined observation values, ionospheric influence factors, and observation noise based on the pseudorange phase and carrier observation equations after correcting the troposphere, ionosphere, and antenna phase center deviations. S3. Build a regional network error model based on multiple antennas, introduce data evaluation and constellation optimization algorithms, and perform multi-dimensional and high-precision real-time dynamic measurement of detection targets; S4. Develop a precise synchronous acquisition mechanism for BeiDou data in complex environments to obtain high-precision relative positioning data for BeiDou monitoring points and benchmark points in complex environments; S5. Design a dual monitoring system to obtain small changes in the detection target and integrate and transmit the data.

2. The BeiDou signal high-precision positioning and measurement method according to claim 1, characterized in that: In S1, the CSSPCT algorithm is used to eliminate the multi-peak of Beidou signals. The principle is as follows: Constructing shape code vectors to obtain the universal cross-correlation function expression of BOC modulation reference and derived modulation signals; Design local code waveform and receive signal to calculate and get signal correlation sub-function, and use reconstruction rule to reassemble sub-function; An additional related branch is added to the traditional tracking loop to form a three-loop structure.

3. The BeiDou signal high-precision positioning and measurement method according to claim 1, characterized in that: The calculation equations for the double-difference triple-frequency pseudorange and carrier combination observation values ​​in S2 are as follows: ； 。 4. The BeiDou signal high-precision positioning and measurement method according to claim 1, characterized in that: In S3, a regional network error model based on multiple antennas is constructed, which specifically includes the following steps: Introducing an observation quality assessment mechanism to conduct credibility analysis on observation data from all visible satellites, prioritizing high-quality observations with high signal-to-noise ratio, few cycle slips, and small multipath errors for solution. In terms of satellite selection strategy, an intelligent constellation optimization algorithm is used, which comprehensively considers the spatial distribution characteristics of the geometric precision factor to ensure that the selected satellites have the best positioning accuracy in terms of spatial geometric configuration; For satellites with poor observation conditions, three-bandwidth lane combined observations are used for processing.

5. The BeiDou signal high-precision positioning and measurement method according to claim 1, characterized in that: In S4, high-precision relative positioning data of Beidou monitoring points and reference points in complex environments is obtained by dual-chip synchronous interface technology through two device interfaces of the monitoring station and the reference station in the region, a GPIO interface, and a baseband event input interface respectively. Maintaining synchronization of the observation times of both sides includes the following two steps: initial alignment after the chip is powered on; and during subsequent operation, the observation times of the two chips are adjusted to maintain synchronization, specifically: the L1 / B1 receiver time and clock difference are corrected in real time according to the L1 / B1 PVT positioning, and the information after 1ms of cumulative adjustment is transmitted to the L1 / B1 MeasCount value to L2 / B2. L2 / B2 is adjusted according to the MeasCount value to maintain synchronization with L1 / B1.

6. The BeiDou signal high-precision positioning and measurement method according to claim 1, characterized in that: The dual monitoring system designed by S5 consists of three parts: the base station, the observation station micro-area monitoring system and the background server. Specifically: The main nodes of the micro-area monitoring systems of the base station and the observation station are equipped with BDS antenna modules, BDS data processing modules and LoRa wireless communication modules, which are used for displacement measurement, baseline length calculation and data exchange between the base station and the observation station main node; The observation station micro-area monitoring system consists of a master node and multiple slave nodes. The slave nodes are equipped with BDS antenna modules, which form a baseline with the antenna module on the master node. They are used to observe data in the micro-area of ​​the observation station, integrate the data, and transmit the integrated data to the reference station through the LoRa module on the master node. The base station is equipped with an LTE module, which is used to send the data integrated by the base station to the background server.

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