Method and device for simultaneous measurement of three-dimensional positioning and gravity potential by using compass frequency observation

Abstract

The application discloses a Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement method, which comprises the following steps: receiving a plurality of frequency signals emitted by a plurality of navigation satellites by using a Beidou multi-frequency receiving device, and acquiring pseudo-range and carrier phase observation values of each frequency point; constructing a frequency observation model containing an earth gravity frequency shift term according to signal frequency variation; fusing frequency observation values obtained based on the frequency observation model with the pseudo-range and carrier phase observation values, and constructing an inversion model of three-dimensional position and gravity potential; and based on the constructed inversion model, performing multi-parameter inversion by using an extended Kalman filter or a least square method, so as to solve the three-dimensional geometric position of a station and the corresponding gravity potential. The application can utilize the frequency variation information contained in the Beidou multi-frequency signal, and simultaneously obtains the three-dimensional space coordinates and synchronously estimates the physical gravity potential of a measurement point.

Description

TECHNICAL FIELD

[0001] The present application belongs to the cross field of satellite navigation and geodetic surveying, and particularly relates to a method and device for realizing synchronous acquisition of three-dimensional geometric coordinates and physical gravity potential of a survey point based on frequency observation of multi-frequency signals of a Beidou navigation system. BACKGROUND

[0002] Global Navigation Satellite System (GNSS) has been widely applied in high-precision positioning and navigation fields, and its main output is three-dimensional spatial position. However, high-end applications such as earth science, surveying and mapping engineering, and time and frequency geodetic surveying also put forward the demand for gravity potential information of survey points. The traditional gravity potential acquisition relies on leveling route and gravity measurement, which is complicated and limited, and is difficult to meet the dynamic, wide-area and automatic measurement demand. With the development of precise time and frequency technology and the theory of relativity, the frequency offset in the navigation signal is considered to carry the gravity field information, which has become a research hotspot. Although some scholars have discussed the gravity potential estimation method based on frequency observation, there is still a lack of a general method and device framework that integrates frequency observation and GNSS positioning observation to realize "one-step measurement of two positions". SUMMARY

[0003] In order to overcome the shortcomings of the prior art, the present application provides a Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement method and device, which can utilize the frequency change information contained in the Beidou multi-frequency signal to simultaneously estimate the physical gravity potential of the survey point while obtaining the three-dimensional spatial coordinates.

[0004] According to one aspect of the present application, a Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement method is provided, comprising:

[0005] receiving multi-frequency signals transmitted by a plurality of navigation satellites using a Beidou multi-frequency receiving device, and obtaining pseudo-range and carrier phase observation values of each frequency point;

[0006] constructing a frequency observation model containing an earth gravity frequency shift term according to the signal frequency change;

[0007] fusing the frequency observation values obtained based on the frequency observation model with the pseudo-range and carrier phase observation values to construct an inversion model of three-dimensional position and gravity potential;

[0008] based on the constructed inversion model, using an extended Kalman filter or a least squares method to perform multi-parameter inversion to solve the three-dimensional geometric position of the survey station and the corresponding gravity potential.

[0009] As a further technical solution, the method further comprises:

[0010] introducing an ionosphere / troposphere delay correction model, a device delay drift model and a noise filtering mechanism to correct the systematic errors of all observation data.

[0011] As a further technical solution, after the frequency observation model containing the gravity frequency shift term of the earth is constructed, the method further comprises:

[0012] Combining the satellite ephemeris and the clock error information to perform observation correction.

[0013] As a further technical solution, in the inversion model constructed, the unknown parameters to be solved include the three-dimensional geometric position, the receiver clock error and the gravity potential of the station.

[0014] As a further technical solution, the extended Kalman filter or the least square method is used for multi-parameter inversion, comprising:

[0015] The unknown parameters are solved by using the ionosphere-free combined time-frequency transfer model of precise point positioning, and the station coordinates and the station clock error parameters at each epoch are solved;

[0016] After the station clock error parameters are solved for a certain period of time, a receiver clock error time sequence is formed, and frequency offset data is calculated;

[0017] According to the frequency offset data, the gravity frequency shift caused by the gravity potential difference is obtained, and the gravity potential at the station is calculated.

[0018] As a further technical solution, the method further comprises:

[0019] According to the solved gravity potential, the orthometric height information or the geoid undulation is transformed.

[0020] According to an aspect of the specification, a Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement device is provided, comprising:

[0021] A Beidou multi-frequency receiving module is used for receiving multi-frequency signals transmitted by a plurality of navigation satellites, and obtaining pseudo-range and carrier phase observation values of each frequency point;

[0022] A frequency comparison module is used for real-time comparison of received signals and local reference frequency, and extraction of signal frequency change;

[0023] A joint solution processing module is used for fusing the frequency observation values obtained based on the frequency observation model with the pseudo-range and carrier phase observation values, constructing an inversion model of three-dimensional position and gravity potential, and using the extended Kalman filter or the least square method for multi-parameter inversion based on the constructed inversion model to solve the three-dimensional geometric position of the station and the corresponding gravity potential.

[0024] As a further technical solution, the device further comprises:

[0025] An error correction module is configured to introduce ionospheric / tropospheric delay correction model, device delay drift model and noise filtering mechanism to correct systematic errors of all observation data, and introduce satellite ephemeris and clock error information to correct observation of frequency observation value.

[0026] As a further technical solution, the device further comprises:

[0027] A result display module is configured to provide an interactive interface or data export function to support visualization, remote transmission and storage of results.

[0028] According to an aspect of the present application, a Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement device is provided, comprising a Beidou multi-frequency receiving device, a memory and a processor, the memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement method.

[0029] The present application aims to provide a method and device capable of utilizing the frequency change information contained in the Beidou multi-frequency signal to simultaneously obtain three-dimensional spatial coordinates and estimate the physical gravity potential of the measurement point, which has obvious independent innovation and frontier nature, and lays a foundation for promoting high-end applications of navigation systems. Compared with the prior art, the present application has the following advantages:

[0030] 1. The three-dimensional geometric position and gravity potential information of the measurement station can be obtained simultaneously, and the unity of position and physical meaning is realized;

[0031] 2. The existing Beidou frequency resources and receiving devices are used, which has good generalizability and engineering feasibility;

[0032] 3. It has wide application prospects in engineering monitoring, high-precision navigation, time-frequency geodetic survey and the like. BRIEF DESCRIPTION OF DRAWINGS

[0033] To make the technical solutions of the present application or prior art clearer, the following will briefly introduce the drawings used in the embodiments or prior art descriptions. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 A Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement method flowchart is provided for the embodiments of the present application.

[0035] Figure 2 A schematic diagram of a Beidou frequency observation three-dimensional positioning and gravity potential synchronous measurement device is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] During the inversion, the unknown parameters to be estimated include the three-dimensional geometric position, receiver clock error, and station gravity potential parameters.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The device also integrates a highly stable local reference frequency standard for real-time correction of frequency drift.

[0051] 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.

[0052] Example 1

[0053] This embodiment illustrates the calculation process for BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement, including the following steps:

[0054] 1. System preparation and equipment configuration.

[0055] 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.

[0056] 2. Acquisition of observational data.

[0057] 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.

[0058] 3. Determination of the three-dimensional geometric position and clock error of the station.

[0059] 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:

[0060]

[0061] 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 defined for ionospheric combinations (n ​​in total). 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.

[0062] 4. Determine the gravity potential of the station.

[0063] 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:

[0064]

[0065] in, express The instantaneous frequency shift corresponding to the epoch.

[0066] The frequency shift results obtained from the measurement can be further expanded as follows:

[0067]

[0068] 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.

[0069] 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.

[0070] 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. :

[0071]

[0072] in, This represents the gravitational potential at the geoid. This represents the speed of light in a vacuum.

[0073] Finally, using the altitude calculation formula, the altitude at station p can be obtained. :

[0074]

[0075] in, This represents the average gravity at point p.

[0076] 5. Error correction and data filtering.

[0077] 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.

[0078] 6. Results output and verification.

[0079] 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.

[0080] Example 2

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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:

[0085] (1) High system integration: It realizes the "co-source acquisition" of position and gravity position information, reducing the number of devices and system complexity;

[0086] (2) Advanced solution model: It introduces a frequency observation model, integrates relativistic correction and error control, and has a solid theoretical foundation;

[0087] (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;

[0088] (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.

[0089] 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.

[0090] 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 signals from multiple navigation satellites at frequencies B1, B2, and B3, and to obtain pseudorange and carrier phase observations for each frequency. 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 an inversion model of three-dimensional position and gravity potential. In the constructed inversion model, the unknown parameters to be solved include three-dimensional geometric position, receiver clock error and station gravity potential. Based on the constructed inversion model, 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 to solve for unknown parameters, calculating the station coordinates and station clock error parameters at each epoch; after solving the station clock error parameters for a certain period of time, a receiver clock error time series is formed, and frequency offset data is calculated; based on the frequency offset data, the gravity frequency shift caused by the gravity potential difference is obtained, and the gravity potential at the station is calculated.

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, The method further includes: Based on the calculated gravity potential, the orthographic height information or geoid undulation is obtained.

5. 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 signals from multiple navigation satellites at frequencies B1, B2, and B3, and to obtain pseudorange and carrier phase observations for each frequency. 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. In the constructed inversion model, the unknown parameters to be solved include three-dimensional geometric position, receiver clock error and station gravity potential. Based on the constructed inversion model, 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 to solve for unknown parameters, calculating the station coordinates and station clock error parameters at each epoch; after solving the station clock error parameters for a certain period of time, a receiver clock error time series is formed, and frequency offset data is calculated; based on the frequency offset data, the gravity frequency shift caused by the gravity potential difference is obtained, and the gravity potential at the station is calculated.

6. The BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement device according to claim 5, 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.

7. The BeiDou frequency observation three-dimensional positioning and gravity potential synchronization measurement device according to claim 6, 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.

8. 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 4.

Images