Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement method and device

Abstract

The invention discloses a Beidou frequency observation three-dimensional positioning and gravitational potential synchronous measurement method, which comprises the following steps: receiving multi-frequency signals transmitted by a plurality of navigation satellites by using Beidou multi-frequency receiving equipment, and obtaining pseudo-range and carrier phase observation values of each frequency point; constructing a frequency observation model containing an earth gravity frequency shift item according to the signal frequency change; fusing a frequency observation value obtained based on a frequency observation model with the pseudo-range and carrier phase observation value, and constructing an inversion model of a three-dimensional position and a gravity potential; and based on the constructed inversion model, carrying out multi-parameter inversion by adopting an extended Kalman filtering or least square method, and solving the three-dimensional geometric position of the observation station and the corresponding gravitational potential thereof. According to the invention, the frequency change information contained in the Beidou multi-frequency signal can be utilized to synchronously estimate the physical gravitational potential of the measuring point while obtaining the three-dimensional space coordinates.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of satellite navigation and geodesy technology, and specifically relates to a method and device for synchronously acquiring the three-dimensional geometric coordinates and physical gravity potential of a measuring point based on the frequency observation of multi-frequency signals from the Beidou navigation system. Background Technology

[0002] Global Navigation Satellite Systems (GNSS) are widely used in high-precision positioning and navigation, primarily outputting three-dimensional spatial position. However, advanced applications such as Earth science, surveying engineering, and time-frequency geodesy also demand gravity potential information from measurement points. Traditional gravity potential acquisition relies on leveling routes and gravity measurements, a cumbersome and limited process that fails to meet the demands of dynamic, wide-area, and automated measurements. With the development of precise time-frequency technology and relativistic theory, frequency shifts in navigation signals are considered to carry gravity field information, making this a research hotspot. Although some scholars have explored gravity potential estimation methods based on frequency observations, a universal method and apparatus framework that integrates frequency observations and GNSS positioning observations to achieve "two-dimensional positioning in one step" is still lacking. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a method and device for synchronous measurement of three-dimensional positioning and gravity potential using BeiDou frequency observation. It can utilize the frequency change information contained in the BeiDou multi-frequency signal to simultaneously estimate the physical gravity potential of the measurement point while obtaining the three-dimensional spatial coordinates.

[0004] According to one aspect of the present invention, a method for three-dimensional positioning and synchronous measurement of gravity potential using BeiDou frequency observation is provided, comprising: The BeiDou multi-frequency receiving equipment is used to receive multi-frequency signals transmitted by multiple navigation satellites and obtain pseudorange and carrier phase observation values ​​at each frequency point. Based on the signal frequency variation, a frequency observation model including the Earth's gravity frequency shift term is constructed; The frequency observations obtained based on the frequency observation model are fused with the pseudorange and carrier phase observations to construct a three-dimensional position and gravity potential inversion model. Based on the constructed inversion model, multi-parameter inversion is performed using extended Kalman filtering or least squares method to solve for the three-dimensional geometric position of the station and its corresponding gravitational potential.

[0005] As a further technical solution, the method also includes: An ionospheric / tropospheric delay correction model, an equipment delay drift model, and a noise filtering mechanism are introduced to systematically correct errors in all observation data.

[0006] As a further technical solution, after constructing a frequency observation model that includes the Earth's gravity frequency shift term, it also includes: Observational corrections are made by combining satellite ephemeris and clock bias information.

[0007] As a further technical solution, the unknown parameters to be solved in the constructed inversion model include three-dimensional geometric position, receiver clock error, and station gravity potential.

[0008] As a further technical solution, extended Kalman filtering or least squares methods are used for multi-parameter inversion, including: Using a precise single-point positioning ionosphere-free combined time-frequency transfer model, the unknown parameters are solved, and the station coordinates and station clock error parameters at each epoch are calculated. After the clock error parameters of the station are processed for a certain period of time, a receiver clock error time series is formed, and the frequency offset data is calculated. Based on the frequency shift data, the gravity frequency shift caused by the gravity potential difference is obtained, and the gravity potential at the station is calculated.

[0009] As a further technical solution, the method also includes: Based on the calculated gravity potential, the orthographic height information or geoid undulation is obtained.

[0010] According to one aspect of the present invention, a BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement device is provided, comprising: The BeiDou multi-frequency receiver module is used to receive multi-frequency signals transmitted by multiple navigation satellites and obtain pseudorange and carrier phase observations at each frequency point. The frequency comparison module is used to compare the received signal with the local reference frequency in real time and extract the signal frequency changes. The joint solution processing module is used to fuse the frequency observation values ​​obtained based on the frequency observation model with the pseudorange and carrier phase observation values ​​to construct an inversion model of three-dimensional position and gravity potential. Based on the constructed inversion model, multi-parameter inversion is performed using extended Kalman filtering or least squares method to solve for the three-dimensional geometric position of the station and its corresponding gravity potential.

[0011] As a further technical solution, the device also includes: The error correction module is used to introduce ionospheric / tropospheric delay correction models, equipment delay drift models and noise filtering mechanisms to systematically correct errors in all observation data, and to introduce satellite ephemeris and clock bias information to correct frequency observations.

[0012] As a further technical solution, the device also includes: The results display module provides an interactive interface or data export function, and supports the visualization, remote transmission and storage of results.

[0013] According to one aspect of the present invention, a BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement device is provided, comprising a BeiDou multi-frequency receiver, a memory, and a processor. The memory stores program instructions that are executed by the processor, and the processor calls the program instructions to execute the BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement method.

[0014] This invention aims to propose a method and device for simultaneously estimating the physical gravity potential of a measurement point by utilizing the frequency variation information contained in the BeiDou multi-frequency signal to acquire three-dimensional spatial coordinates. It possesses significant independent innovation and cutting-edge technology, laying the foundation for promoting high-end applications of navigation systems. Compared with existing technologies, the beneficial effects of this invention are: 1. It can simultaneously acquire the three-dimensional geometric position and gravity potential information of the station, realizing the unification of position and physical meaning; 2. Utilizing existing BeiDou frequency resources and receiving equipment, it has good scalability and engineering feasibility; 3. It has broad application prospects in engineering monitoring, high-precision navigation, and time-frequency geodetic surveying. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the BeiDou frequency observation three-dimensional positioning and gravity potential synchronous measurement method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement device provided in an embodiment of the present invention. Detailed Implementation

[0017] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0019] This invention provides a method for synchronous measurement of three-dimensional positioning and gravity potential using BeiDou frequency observation, such as... Figure 1 As shown, firstly, the BeiDou multi-frequency receiving equipment is used to receive multi-frequency signals transmitted by multiple navigation satellites to obtain pseudorange and carrier phase observations at each frequency point. Next, based on signal frequency variations, a frequency observation model incorporating the Earth's gravity frequency shift term is constructed. Subsequently, the frequency observations obtained based on the frequency observation model are fused with the pseudorange and carrier phase observations to construct an inversion model of three-dimensional position and gravity potential. Then, based on the constructed inversion model, extended Kalman filtering or least squares methods are used for multi-parameter inversion to solve for the station's three-dimensional geometric position and its corresponding gravity potential.

[0020] The embodiments of the present invention overcome the technical obstacle that traditional gravity potential measurement needs to be separated from the positioning process, improve the calculation efficiency and system integration, and are applicable to multiple application scenarios such as unified elevation benchmarks, precision navigation, engineering monitoring and time-frequency measurement. They have important theoretical significance and engineering practical value.

[0021] In the embodiments of the present invention, when receiving multi-frequency signals and acquiring observation values, the BeiDou multi-frequency receiving equipment is used to receive signals at different frequencies transmitted by multiple navigation satellites and acquire basic observation data such as pseudorange and carrier phase.

[0022] Furthermore, by using the comparison results between the received signal and the local reference frequency, a frequency observation model including the Earth's gravity frequency shift term is constructed, and observation corrections are made by combining satellite ephemeris and clock bias information.

[0023] In constructing the solution model and implementing the inversion algorithm, this invention builds a solution framework based on the aforementioned observations, integrates variables such as position parameters and clock error parameters, and performs multi-parameter inversion using extended Kalman filtering or least squares methods. This allows for the precise determination of the station's three-dimensional geometric position and the simultaneous acquisition of the clock error time series of the station's high-precision atomic clock. Furthermore, the obtained clock error time series is analyzed and processed, and the corresponding gravitational potential at the station can be calculated using the gravitational potential frequency shift equation. Therefore, simultaneous measurement of the three-dimensional geometric position and gravitational potential is achieved.

[0024] During the inversion, the unknown parameters to be estimated include the three-dimensional geometric position, receiver clock error, and station gravity potential parameters.

[0025] Furthermore, in this embodiment of the invention, the output station receiver has a three-dimensional geometric position in the global coordinate system, and at the same time estimates its gravity potential value or the gravity potential difference between it and the reference point, which can be further converted into morphological indicators such as orthometric height and geoid undulation.

[0026] The embodiments of the present invention also introduce an ionospheric / tropospheric delay correction model, an equipment delay drift model, and a noise filtering mechanism to systematically correct errors in all observation data.

[0027] Based on the same inventive concept as the foregoing embodiments, this embodiment of the invention also provides a BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement device, such as... Figure 2 As shown, it includes: a BeiDou multi-frequency receiving module, used to receive multi-frequency signals transmitted by multiple navigation satellites and obtain pseudorange and carrier phase observation values ​​at each frequency point; a frequency comparison module, used to compare the received signal with the local reference frequency in real time and extract the signal frequency changes; and a joint calculation and processing module, used to fuse the frequency observation values ​​obtained based on the frequency observation model with the pseudorange and carrier phase observation values ​​to construct an inversion model of three-dimensional position and gravity potential. Based on the constructed inversion model, multi-parameter inversion is performed using extended Kalman filtering or least squares method to solve for the three-dimensional geometric position of the station and its corresponding gravity potential.

[0028] In this embodiment of the invention, the joint solution processing module integrates an extended Kalman filter or a least squares estimation module. The joint solution processing module performs joint modeling and calculation of three-dimensional coordinates and gravity potential, supporting both real-time and post-processing modes. The frequency comparison module supports multi-channel parallel processing, improving the real-time performance and accuracy of frequency offset extraction.

[0029] Furthermore, the device also includes: an error correction module, used to introduce an ionospheric / tropospheric delay correction model, an equipment delay drift model and a noise filtering mechanism to systematically correct errors in all observation data, and to introduce satellite ephemeris and clock bias information to correct frequency observations.

[0030] Furthermore, the device also includes a result display module, used to provide an interactive interface or data export function, supporting result visualization, remote transmission, and storage. The result display unit supports converting gravity potential estimates into elevation differences or equipotential surface undulation differences. The result display module can output or remotely transmit the acquired coordinate information and gravity potential data in real time.

[0031] The device also integrates a highly stable local reference frequency standard for real-time correction of frequency drift.

[0032] To illustrate the technical solution of the present invention more specifically, the following detailed description, in conjunction with typical embodiments, details the practical application process and technical implementation of the method and apparatus for determining three-dimensional position and gravity potential synchronization based on BeiDou signal frequency observation. However, it should be understood that these embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment illustrates the calculation process for BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement, including the following steps: 1. System preparation and equipment configuration.

[0035] Several typical measurement points were selected in the field, and GNSS receiving terminals capable of receiving BeiDou B1, B2, and B3 signals were deployed. At the same time, a high-precision and high-stability local frequency source (such as a hydrogen clock) was configured to ensure that the frequency comparison accuracy meets the calculation requirements.

[0036] 2. Acquisition of observational data.

[0037] Start the receiver and continuously record observations including pseudorange and carrier phase, setting the sampling rate to 1 s or higher (e.g., 0.1 s), and save it as a mixed file in RINEX and frequency difference formats.

[0038] 3. Determination of the three-dimensional geometric position and clock error of the station.

[0039] The unknown parameters are solved using a precise single-point positioning ionosphere-free (IF) time-frequency transfer model. The state vector is set as follows:

[0040] in, For the receiver's three-dimensional coordinates, This refers to the receiver clock bias (the clock bias between the atomic clock at the station and the atomic clock on the satellite). For tropospheric zenith wet delay, The ambiguities are n in total, representing the ionospheric-free combination. By constructing pseudorange observation equations and carrier phase equations, and using Kalman filtering for parameter estimation, precise determination of station coordinates and clock error parameters at each epoch can be achieved.

[0041] 4. Determine the gravity potential of the station.

[0042] After a period of calculation, the clock error parameters of each station can be obtained for each epoch. The corresponding station clock bias results constitute a receiver clock bias time series. The corresponding frequency offset data can be obtained using the following formula:

[0043] in, express The instantaneous frequency shift corresponding to the epoch.

[0044] The frequency shift results obtained from the measurement can be further expanded as follows:

[0045] in This indicates the gravitational frequency shift caused by the difference in gravitational potential. This indicates the system frequency offset between ground-based atomic clocks and satellite atomic clocks. This indicates the frequency drift between ground-based atomic clocks and satellite atomic clocks. and These represent the effects of the ionosphere and the troposphere, respectively. This represents the sum of other unmodeled errors.

[0046] It should be noted that before launch, the BeiDou satellites undergo frequency modulation to correct for the effects of inherent terms in relativity. The remaining effects of relativistic elliptical orbits are corrected during data processing using appropriate models. This is done to maintain time consistency between the satellite clock and the ground clock. In fact, after these corrections, it is equivalent to normalizing the satellite clock frequency to the geoid. Thus, regardless of which satellite a ground station tracks, in terms of time and frequency attributes, it is equivalent to comparing the station's clock with a clock located on the geoid.

[0047] Therefore, when the satellite system is strictly reduced to the geoid and the atomic clocks at the stations are precisely calibrated beforehand, the gravitational potential at a given station p can be directly determined after a period of tracking and observation of the BeiDou satellites. :

[0048] in, This represents the gravitational potential at the geoid. This represents the speed of light in a vacuum.

[0049] Finally, using the altitude calculation formula, the altitude at station p can be obtained. :

[0050] in, This represents the average gravity at point p.

[0051] 5. Error correction and data filtering.

[0052] Real-time corrections are performed using IGS precise ephemeris and clock bias, combined with RTCM format differential data. Ionospheric delay is calculated using a dual-frequency ionospheric de-de-situation model to eliminate the influence of first-order terms, while tropospheric delay is calculated using the Saastamoinen model with elevation angle-related weighting.

[0053] 6. Results output and verification.

[0054] After the calculation is completed, the three-dimensional coordinates and gravity potential estimate are output. The gravity potential is compared with the theoretical value calculated by the EGM2008 geoid model. The error is within ±0.3 m² / s², and the error of the converted orthographic height does not exceed 3 cm, which verifies the practicality and effectiveness of the method described in this embodiment.

[0055] Example 2

[0056] This embodiment illustrates a synchronous monitoring system in an engineering application scenario. The synchronous monitoring system is implemented using the BeiDou frequency observation three-dimensional positioning and gravity potential synchronous measurement device.

[0057] The aforementioned synchronous measurement device was deployed at a large-scale infrastructure construction site to achieve dynamic monitoring of the spatial stability and gravitational potential changes of key engineering points. The device collects continuous frequency and location observation data, and performs dynamic calculations and anomaly alarms with a 5-minute time resolution. Compared to the traditional combination of height measurement and gravimeter, this device significantly reduces the number of devices, improves system stability and measurement efficiency, and is particularly suitable for engineering scenarios such as tunnel deformation monitoring and seawall settlement monitoring.

[0058] In summary, the "method and device for synchronous measurement of three-dimensional positioning and gravity potential based on BeiDou frequency observation" proposed in this invention innovatively integrates conventional GNSS observation technology with relativistic frequency observation theory, establishes a joint solution model, and achieves the synchronous measurement of three-dimensional coordinates and gravity potential information on a single GNSS platform for the first time.

[0059] Compared to the multi-step process of traditional gravity potential measurement that relies on leveling networks and gravimeters, the method of this invention has the following significant advantages: (1) High system integration: It realizes the "co-source acquisition" of position and gravity position information, reducing the number of devices and system complexity; (2) Advanced solution model: It introduces a frequency observation model, integrates relativistic correction and error control, and has a solid theoretical foundation; (3) Excellent accuracy and stability: The frequency observation is less affected by noise, and a stable gravity potential estimate can be obtained by combining filtering methods; (4) Wide range of applicable scenarios: It can be widely applied to fields such as elevation benchmark unification, satellite gravity calibration, engineering monitoring and time and frequency benchmark synchronization.

[0060] In summary, this invention has good engineering feasibility and application prospects, and is of great significance for promoting the integrated development of navigation and positioning technology and modern geodesy.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for synchronous measurement of three-dimensional positioning and gravity potential using BeiDou frequency observation, characterized in that, include: The BeiDou multi-frequency receiving equipment is used to receive multi-frequency signals transmitted by multiple navigation satellites and obtain pseudorange and carrier phase observation values ​​at each frequency point. Based on the signal frequency variation, a frequency observation model including the Earth's gravity frequency shift term is constructed; The frequency observations obtained based on the frequency observation model are fused with the pseudorange and carrier phase observations to construct a three-dimensional position and gravity potential inversion model. Based on the constructed inversion model, multi-parameter inversion is performed using extended Kalman filtering or least squares method to solve for the three-dimensional geometric position of the station and its corresponding gravitational potential.

2. The method for synchronous measurement of three-dimensional positioning and gravity potential using BeiDou frequency observation according to claim 1, characterized in that, The method further includes: An ionospheric / tropospheric delay correction model, an equipment delay drift model, and a noise filtering mechanism are introduced to systematically correct errors in all observation data.

3. The method for synchronous measurement of three-dimensional positioning and gravity potential using BeiDou frequency observation according to claim 2, characterized in that, After constructing a frequency observation model that includes the Earth's gravity frequency shift term, it also includes: Observational corrections are made by combining satellite ephemeris and clock bias information.

4. The method for synchronous measurement of three-dimensional positioning and gravity potential using BeiDou frequency observation according to claim 1, characterized in that, In the constructed inversion model, the unknown parameters to be solved include the three-dimensional geometric position, receiver clock error, and station gravity potential.

5. The method for synchronous measurement of three-dimensional positioning and gravity potential using BeiDou frequency observation according to claim 4, characterized in that, Multi-parameter inversion is performed using extended Kalman filtering or least squares methods, including: Using a precise single-point positioning ionosphere-free combined time-frequency transfer model, the unknown parameters are solved, and the station coordinates and station clock error parameters at each epoch are calculated. After the clock error parameters of the station are processed for a certain period of time, a receiver clock error time series is formed, and the frequency offset data is calculated. Based on the frequency shift data, the gravity frequency shift caused by the gravity potential difference is obtained, and the gravity potential at the station is calculated.

6. The method for synchronous measurement of three-dimensional positioning and gravity potential using BeiDou frequency observation according to claim 1, characterized in that, The method further includes: Based on the calculated gravity potential, the orthographic height information or geoid undulation is obtained.

7. A BeiDou frequency observation three-dimensional positioning and gravity potential synchronous measurement device, characterized in that, include: The BeiDou multi-frequency receiver module is used to receive multi-frequency signals transmitted by multiple navigation satellites and obtain pseudorange and carrier phase observations at each frequency point. The frequency comparison module is used to compare the received signal with the local reference frequency in real time and extract the signal frequency changes. The joint solution processing module is used to fuse the frequency observation values ​​obtained based on the frequency observation model with the pseudorange and carrier phase observation values ​​to construct an inversion model of three-dimensional position and gravity potential. Based on the constructed inversion model, multi-parameter inversion is performed using extended Kalman filtering or least squares method to solve for the three-dimensional geometric position of the station and its corresponding gravity potential.

8. The BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement device according to claim 7, characterized in that, The device further includes: The error correction module is used to introduce ionospheric / tropospheric delay correction models, equipment delay drift models and noise filtering mechanisms to systematically correct errors in all observation data, and to introduce satellite ephemeris and clock bias information to correct frequency observations.

9. The BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement device according to claim 7, characterized in that, The device further includes: The results display module provides an interactive interface or data export function, and supports the visualization, remote transmission and storage of results.

10. A BeiDou frequency observation three-dimensional positioning and gravity potential synchronous measurement device, characterized in that, The device includes a BeiDou multi-frequency receiver, a memory, and a processor. The memory stores program instructions that are executed by the processor. The processor calls the program instructions to execute the BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement method according to any one of claims 1 to 6.

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