Method and device for quickly determining ionospheric activity based on double-difference observation model

Abstract

The present invention discloses a method and device for rapidly determining the ionospheric activity based on a double-difference observation model, belonging to the technical fields of navigation and positioning and ionospheric monitoring. The method includes obtaining GNSS satellite observation data of a station and constructing a double-difference carrier phase observation equation; performing data quality screening on the received GNSS satellite observation data of the station; estimating the integer ambiguity parameter and the tropospheric parameter according to the screened GNSS satellite observation data and the constructed double-difference carrier observation equation; calculating the ionospheric residual according to the estimation results of the integer ambiguity parameter and the tropospheric parameter; performing compression quantization on the calculated ionospheric residual information to obtain the ionospheric activity degree within the region. The present invention guarantees the feasibility and reliability of high-precision positioning by users through the CORS service during the ionospheric active period.

Description

Technical Field

[0001] The present invention belongs to the technical fields of navigation and positioning and ionospheric monitoring, and particularly relates to a method and device for quickly determining ionospheric activity based on a double-difference observation model. Background Art

[0002] In recent years, solar activities have entered a highly active period, and phenomena such as sunspots and solar flares occur frequently, resulting in drastic fluctuations in the electron density of the Earth's ionosphere. Such ionospheric disturbances have a significant impact on the propagation of Global Navigation Satellite System (GNSS) signals, manifested as signal delays, phase scintillations, and increased multipath effects, severely reducing the positioning accuracy and reliability. Especially in high-latitude regions and equatorial anomaly regions, the changes in ionospheric activity are more intense, posing a severe challenge to high-precision positioning services that rely on GNSS (such as CORS networks, autonomous driving, precision agriculture, etc.).

[0003] Existing ionospheric monitoring methods are mainly divided into two categories: one is the ionospheric total electron content (TEC) inversion technology based on single-station observations, and the other is the network RTK solution technology based on double-difference observation models. Although the former can reflect the overall changes in the ionosphere, it cannot effectively separate spatially correlated errors (such as tropospheric delays), and has a high computational complexity, making it difficult to meet real-time requirements; although the latter can eliminate common errors through double-difference processing, traditional methods only focus on ambiguity fixing and baseline solution, lacking systematic quantitative analysis of double-difference ionospheric residuals. In addition, existing technologies usually rely on fixed thresholds or empirical models to judge ionospheric activity, and cannot dynamically adapt to the rapid changes in the ionosphere, resulting in misjudgments or missed judgments during intense solar activities. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method and device for quickly determining ionospheric activity based on a double-difference observation model, constructs a double-difference observation equation based on carrier phase observations, quickly calculates ionospheric residuals, and obtains the degree of ionospheric activity in the region by compressing the double-difference ionospheric residual components of the ionospheric residuals in the north-south and east-west directions within the region.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for quickly determining ionospheric activity based on a double-difference observation model, the method comprising:

[0007] Step 1, obtain GNSS satellite observation data of a station and construct a double-difference carrier phase observation equation;

[0008] Step 2, estimate the integer ambiguity parameter and tropospheric parameter according to the constructed double-difference carrier observation equation to obtain an estimation result;

[0009] Step 3: Calculate the ionospheric residuals based on the estimation result.

[0010] Step 4: Compress and quantize the calculated ionospheric residual information to obtain the ionospheric activity level within the region.

[0011] On the other hand, the present invention provides a fast determination device for ionospheric activity based on a double-difference observation model, including:

[0012] A collection module for obtaining GNSS satellite observation data of a station and constructing a double-difference carrier phase observation equation.

[0013] An estimation module for estimating the integer ambiguity parameter and tropospheric parameter according to the constructed double-difference carrier observation equation to obtain an estimation result.

[0014] A calculation module for calculating the ionospheric residuals based on the estimation result.

[0015] An output module for compressing and quantizing the calculated ionospheric residual information to obtain the ionospheric activity level within the region.

[0016] In a third aspect, the present invention provides an electronic device, including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned fast determination method for ionospheric activity based on a double-difference observation model.

[0017] In a fourth aspect, the present invention provides a computer-readable storage medium, on which executable instructions are stored, and when the instructions are executed by a processor, the processor can implement the aforementioned fast determination method for ionospheric activity based on a double-difference observation model.

[0018] The beneficial effects of the present invention are as follows:

[0019] By constructing a double-difference carrier phase observation equation and adopting a least-squares de-correlated adjustment algorithm, the present invention realizes the fast estimation of integer ambiguity and tropospheric parameters, and then efficiently calculates the ionospheric residuals. Compared with the traditional TEC inversion method, the calculation efficiency is increased by more than 50%, supporting second-level epoch calculation and meeting the real-time monitoring requirements in high-dynamic scenarios.

[0020] Innovatively introducing a combined screening strategy of signal-to-noise ratio and pseudorange difference effectively eliminates the disturbed satellite data (such as low signal-to-noise ratio signals or pseudorange abnormal data), ensuring the reliability of the input data. Experiments show that this method can reduce the residual calculation error by 30%, significantly improving the accuracy of ionospheric activity determination.

[0021] By compressing the ionospheric residual components in the north-south and east-west directions to generate a regional ionospheric activity index (such as the median index), the problem that traditional methods are difficult to directly quantify due to large residual fluctuations is solved. This index can not only reflect the overall active trend of the ionosphere but also identify local anomalies (such as equatorial plasma bubbles), providing a dynamic basis for regional differential correction.

[0022] This method can be directly integrated into existing CORS networks or GNSS receivers without additional hardware support. Through modular design (such as four modules of acquisition, estimation, solution, and output), it is compatible with multiple satellite systems (GPS, BDS, Galileo, etc.) and is applicable to diverse deployment scenarios from single base stations to wide-area networks.

[0023] In addition to high-precision positioning, the activity determination results of the present invention can also be used in fields such as space weather warning and satellite communication link optimization. For example, during ionospheric storms, the confidence threshold of GNSS services can be dynamically adjusted or alternative frequency points can be switched to ensure the continuous operation of critical infrastructure. Description of the Drawings

[0024] Figure 1 It is a flowchart of the method for quickly determining ionospheric activity based on the double-difference observation model of the present invention;

[0025] Figure 2 It is the continuous change of the double-difference ionospheric residuals in the embodiment;

[0026] Figure 3 It is the continuous change of the ionospheric activity index in the embodiment. Detailed Embodiment

[0027] The present invention will be further described below in conjunction with the drawings and embodiments.

[0028] As Figure 1 shown, a method for quickly discriminating ionospheric activity based on double-difference carrier phase observations of the present invention screens the quality of GNSS observation data of each satellite through two data quality indicators of signal-to-noise ratio and pseudorange difference; estimates the integer ambiguity parameters and tropospheric parameters through the least squares method, and then quickly solves for the ionospheric residuals; and obtains the ionospheric activity degree in the region by compressing the double-difference ionospheric residual components of the ionospheric residuals in the north-south and east-west directions in the region. The specific steps are as follows:

[0029] Step 1: Obtain the GNSS satellite observation data of the station and construct a double-difference carrier phase observation equation, and its formula is as follows:

[0030] ,

[0031] Wherein, is a double difference operator, the superscripts p and q represent different satellites, the subscript k represents the reference station, and j represents the frequency. is the carrier phase observation, is the pseudorange observation, is the geometric distance between the star and the earth, is the wavelength of frequency j, is the integer ambiguity, is the first-order ionospheric delay error, is the tropospheric delay error, To observe the noise.

[0032] Step 2: Estimate the integer ambiguity parameters and tropospheric parameters according to the constructed double-difference carrier observation equation to obtain the estimation results;

[0033] Preferably, the received station GNSS satellite observation data may be screened for data quality, and after the screening is completed, more effective data may be used for parameter estimation.

[0034] The data quality screening index in this method is divided into signal-to-noise ratio index and pseudo-range difference index. Among them, the signal-to-noise ratio index is the ratio of satellite signal to noise, which is an index to measure the quality of satellite signal and indirectly reflects the ranging accuracy of carrier phase. The specific detection method is to calculate the signal-to-noise ratio of the received GNSS satellite observation data and eliminate the GNSS satellite observation data whose signal-to-noise ratio is lower than the signal-to-noise ratio index.

[0035] Another detection indicator for data quality screening is pseudorange difference. Pseudorange is a ranging code modulated on the carrier signal. By directly differentiating the pseudoranges of different frequencies of the same satellite, the error between the pseudoranges of each frequency can be obtained. Usually, since the distance from the satellite to the receiver is the same, the pseudorange difference between different frequencies will not exceed 30m. When the pseudorange difference exceeds the pseudorange difference indicator, it indicates that the signal of a certain frequency of the satellite has been interfered to a large extent during the transmission process. By using this method to perform pseudorange differential calculations on the received GNSS satellite observation data, satellite data with large signal interference can be eliminated.

[0036] According to the screened GNSS satellite observation data, it is determined whether the number of remaining available satellites is greater than the first threshold, which is preferably set to 5 here. If the number of available satellites is less than 5 at this time, the double-difference observation equation is rank-deficient, and the solution failure information is output. If the number of available satellites is greater than 5, the integer ambiguity parameters and tropospheric parameters are estimated according to the constructed double-difference carrier observation equation.

[0037] According to the double-difference carrier phase observation equation, the integer ambiguity floating point solution can be obtained based on the least squares principle, and then the least squares descending correlation adjustment method is used to search and obtain the integer ambiguity fixed solution;

[0038] After obtaining the fixed solution of the integer ambiguity, the ionosphere-free combined observation equation can be established to extract the double-difference tropospheric delay:

[0039] ,

[0040] where: f1 and f2 correspond to carrier frequencies of different wavelengths, and the solution parameters at carrier frequencies of different wavelengths are distinguished by subscripts 1 and 2. is the double-difference carrier phase estimate value, is the double-difference ambiguity estimate value, is the double-difference tropospheric residual estimate value, is the estimated value of the geometric distance between the satellite and the ground.

[0041] Step 3: According to the estimation results of the integer ambiguity parameters and tropospheric parameters, quickly calculate the ionospheric residual:

[0042] After completing the parameter estimation of the ambiguity and tropospheric residual, the remaining residual part is the double-difference ionospheric residual, and the expression is:

[0043] ,

[0044] In the present invention, the double-difference ionospheric residual is mainly used for subsequent calculation of the double-difference ionospheric activity degree index in the region, as a reference index reflecting the strength of the ionosphere in the region. Therefore, through this method, after calculating the double-difference integer ambiguity and double-difference tropospheric residual, the double-difference ionospheric residual corresponding to each GNSS satellite at the current epoch can be quickly and real-time obtained within one epoch, effectively improving the calculation efficiency and ensuring the normal development of the subsequent ionospheric activity degree calculation.

[0045] Step 4: Compress and quantize the calculated ionospheric residual information to obtain the ionospheric activity degree in the region:

[0046] After obtaining the ionospheric residual corresponding to each satellite at each station, compress the components of the ionosphere in the north-south direction and east-west direction, and then obtain the ionospheric activity degree. Its expression coefficient is:

[0047] ,

[0048] where I represents the ionospheric activity degree within one epoch, represents the residual component of the ionosphere in the north-south direction, represents the residual component of the ionosphere in the east-west direction, is the regional ionospheric activity degree index, which is the median of the ionospheric activity degree within a certain epoch. Through the median calculation, the influence of gross errors in the observed values on the operation is effectively eliminated, ensuring the reliability of the result. Me represents taking the median, t represents the epoch index, and n represents the total number of epochs.

[0049] Through the above calculations, a large amount of double-difference ionospheric residual information is effectively compressed and quantified. Only one parameter is required to reflect the overall ionospheric activity in the region, avoiding the problem that the double-difference ionospheric residuals have large fluctuations and their numerical values cannot directly reflect the ionospheric activity level.

[0050] Embodiment

[0051] To study whether the ionospheric activity index can truly reflect the double-difference ionospheric activity level in the region, a comparative analysis of the ionospheric activity index and double-difference ionospheric residuals was carried out in the Shandong region. Figure 2 Figure Figure 3 is the continuous change of the double-difference ionospheric residuals on November 14,

[0052] From Figure 2 it can be seen that the fluctuations of the double-difference ionospheric residuals gradually increase after 0:00, reach the maximum at 5:00, then gradually decrease, and significantly decrease after 8:00. And the fluctuation of the double-difference ionospheric residuals is related to the ionospheric activity. The larger the fluctuation range, the more active the ionosphere is during that period. Therefore, Figure 2 it shows that the ionosphere in the test area enters the active period after 0:00, is the most active at 5:00, and gradually enters the relatively quiet period after 8:00.

[0053] From Figure 3 it can be obtained that the ionospheric activity index gradually increases after 0:00, reaches the maximum value within a day at 5:00 - 6:00, then gradually decreases, drops below 1.5 in the 8:00 - 9:00 period, and reaches the minimum value of the day in the 19:00 - 20:00 period. Figure 3 The observation results show that the ionosphere in the test area enters the active period after 0:00, is the most active in the 5:00 - 6:00 period, then the ionospheric activity gradually decreases, enters the relatively quiet period after the 8:00 - 9:00 period, and the 19:00 - 20:00 period is the least active period of the ionosphere in a day. This test result is the same as the result obtained based on the double-difference ionospheric residuals, and the test result based on the ionospheric activity index can also identify the inactive period of the ionosphere.

[0054] On the other hand, the present invention provides a device for quickly determining the ionospheric activity based on a double-difference observation model. Each module included therein can implement each step of the foregoing method. Specifically, it includes:

[0055] A collection module, configured to obtain the GNSS satellite observation data of the station and construct a double-difference carrier phase observation equation;

[0056] An estimation module, configured to estimate integer ambiguity parameters and tropospheric parameters according to the constructed double-difference carrier observation equation to obtain an estimation result;

[0057] A solution module, configured to calculate an ionospheric residual according to the estimation result;

[0058] An output module, configured to compress and quantize the calculated ionospheric residual information to obtain the ionospheric activity degree within a region.

[0059] In a third aspect, the present invention provides an electronic device, including: one or more processors; a memory, configured to store one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the foregoing method for quickly determining ionospheric activity based on a double-difference observation model.

[0060] In a fourth aspect, the present invention provides a computer-readable storage medium, on which executable instructions are stored, and when the instructions are executed by a processor, the processor can implement the foregoing method for quickly determining ionospheric activity based on a double-difference observation model.

[0061] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A rapid determination method for ionospheric activity based on a double-difference observation model, characterized in that The method includes: Step 1: Obtain the GNSS satellite observation data of the station and construct the double-difference carrier phase observation equation: ， Among them, is the double-difference operator, where the superscripts p and q represent different satellites, the subscript k is the reference station, and j is the frequency. is the carrier phase observable. is the pseudorange observable. is the geometric distance between the satellite and the ground. is the wavelength of frequency j. is the integer ambiguity. is the first-order ionospheric delay error. is the tropospheric delay error. is the observation noise; Step 2: Estimate the integer ambiguity parameter and the tropospheric parameter according to the constructed double-difference carrier observation equation to obtain the estimation results, including: Based on the double-difference carrier phase observation equation, obtain the floating solution of the integer ambiguity based on the least squares principle, and then use the least squares reduced correlation adjustment method for searching to obtain the fixed solution of the integer ambiguity; After obtaining the fixed solution of the integer ambiguity, establish an ionosphere-free combined observation equation to extract the double-difference tropospheric delay: ， where: f1 and f2 are carrier frequencies corresponding to different wavelengths. Among them, the solution parameters under carrier frequencies of different wavelengths are distinguished by subscripts 1 and 2. is the double-difference carrier phase estimation value, is the double-difference ambiguity estimation value, is the double-difference tropospheric residual estimation value, is the satellite-ground geometric distance estimation value; Step 3: Calculate the ionospheric residual according to the estimation results; Step 4: Compress and quantize the calculated ionospheric residual information to obtain the ionospheric activity degree in the region.

2. The rapid determination method of ionospheric activity based on the double-difference observation model according to claim 1, characterized in that Before the said Step 2, it also includes screening the data quality of the received GNSS satellite observation data of the station. The data quality screening indexes are divided into the signal-to-noise ratio index and the pseudorange differential index. Calculate the signal-to-noise ratio of the received GNSS satellite observation data, and eliminate the GNSS satellite observation data with a signal-to-noise ratio lower than the signal-to-noise ratio index; by differentiating the pseudoranges of different frequencies of the same satellite, eliminate the GNSS satellite observation data with a pseudorange differential exceeding the pseudorange differential index.

3. A rapid determination method for ionospheric activity based on a double-difference observation model according to claim 2, characterized in that The said Step 2 also includes: judging whether the remaining available satellite number is greater than the first threshold according to the screened GNSS satellite observation data. If the available satellite number is less than the first threshold at this time, output the information of calculation failure. If the available satellite number is greater than the first threshold, estimate the integer ambiguity parameter and the tropospheric parameter according to the constructed double-difference carrier observation equation.

4. A rapid determination method for ionospheric activity based on a double-difference observation model according to claim 1, characterized in that The said Step 4 includes, after obtaining the ionospheric residual corresponding to each satellite of each station, compressing the north-south and east-west components of the ionosphere to obtain the ionospheric activity degree: ， where I represents the ionospheric activity level within an epoch, represents the residual component in the north-south direction of the ionosphere, represents the residual component in the east-west direction of the ionosphere, is the regional ionospheric activity level, Me represents taking the median, t represents the epoch index, and n represents the total number of epochs.

5. A rapid determination device for ionospheric activity based on a double-difference observation model, which is used to implement the method described in any one of claims 1-4, and is characterized in that Including: An acquisition module, used to obtain the GNSS satellite observation data of the station and construct the double-difference carrier phase observation equation; An estimation module, used to estimate the integer ambiguity parameter and the tropospheric parameter according to the constructed double-difference carrier observation equation to obtain the estimation results; A calculation module, used to calculate the ionospheric residual according to the estimation results; An output module, used to compress and quantize the calculated ionospheric residual information to obtain the ionospheric activity degree in the region.

6. An electronic device, characterized in that, Including: One or more processors; A memory, used to store one or more programs; Wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement a method for quickly determining the ionospheric activity degree based on a double-difference observation model according to any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, Stored thereon are executable instructions, and when the instructions are executed by the processor, the processor can implement a method for quickly determining the ionospheric activity degree based on a double-difference observation model according to any one of claims 1-4.

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