Ionized layer STEC extraction method and system

Abstract

The invention relates to an ionosphere STEC extraction method and system, a computer program product, computer equipment and a storage medium, and relates to the technical field of satellite navigation positioning, and the method comprises the steps: constructing a PPP observation model containing a receiver DCB parameter based on a received multi-system multi-frequency satellite observation value; performing measurement updating on the PPP observation model through PPP filtering to obtain a state vector and a variance-covariance matrix thereof; performing ambiguity fixation on the state vector and the variance-covariance matrix thereof to obtain ionosphere delay; and converting the ionospheric delay amount into STEC. Compared with the prior art, the method aims at eliminating the influence of the receiver DCB on STEC extraction, and unbiased STEC is provided for follow-up work such as ionosphere monitoring and modeling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of satellite navigation and positioning, in particular to an ionospheric STEC extraction method and system, a computer program product, a computer device and a storage medium. BACKGROUND

[0002] The ionospheric delay is one of the main error sources in Global Navigation Satellite System (GNSS) positioning, and its size is inversely proportional to the square of the signal frequency and proportional to the Slant Total Electron Content (STEC). At present, the non-difference non-combination precise point positioning (PPP) technology is often used to extract high-precision STEC. However, in the traditional PPP model, the ionospheric parameter absorbs the receiver DCB, which may cause the following problems: abnormal situation of negative extraction value; in order to ensure the uniformity of the receiver DCB absorbed by the model values of each satellite, some satellites that cannot be observed by the station are usually excluded, resulting in that the number of modeling satellites is lower than the actual number of satellites; if the receiver DCB is jointly estimated by multiple satellites during modeling, the VTEC projection is not conducive to the modeling accuracy.

[0003] Therefore, how to effectively eliminate the influence of the receiver DCB in the PPP observation model and improve the accuracy of the ionospheric parameter has become a technical problem to be solved at present. Extracting high-precision and unbiased STEC has important significance in ionospheric monitoring, ionospheric modeling and PPP-RTK technology promotion. SUMMARY

[0004] Therefore, it is necessary to provide an ionospheric STEC extraction method and system, a computer program product, a computer device and a storage medium capable of eliminating the influence of the receiver DCB on the extraction of the STEC, providing unbiased STEC for subsequent ionospheric monitoring, modeling and other work, in order to solve the technical problems of abnormal situation of negative extraction value, low number of modeling satellites compared with the actual number of satellites and VTEC projection not conducive to modeling accuracy after the ionospheric parameter absorbs the receiver DCB.

[0005] To solve the above technical problems, the technical solutions of the present application are as follows: In a first aspect, an ionospheric STEC extraction method comprises: building a PPP observation model containing a receiver DCB parameter based on received multi-system multi-frequency satellite observation values; updating the PPP observation model by PPP filtering to obtain a state vector and a variance-covariance matrix thereof; fixing the ambiguity of the state vector and the variance-covariance matrix to obtain ionospheric delay; convert the ionospheric delay into STEC.

[0006] In a second aspect, an ionospheric STEC extraction system comprises: an observation model construction module configured to construct a PPP observation model containing the receiver DCB parameter based on the received multi-system multi-frequency satellite observation value; an observation model updating module configured to update the PPP observation model through PPP filtering to obtain a state vector and a variance-covariance matrix; an ambiguity fixing module configured to fix the ambiguity of the state vector and the variance-covariance matrix to obtain ionospheric delay; a STEC conversion module configured to convert the ionospheric delay into STEC.

[0007] In a third aspect, a computer program product comprises computer programs or computer executable instructions, which, when executed by a processor, implement an ionospheric STEC extraction method as described above.

[0008] In a fourth aspect, an electronic device comprises: a memory configured to store computer executable instructions or computer programs; a processor configured to execute the computer executable instructions or computer programs stored in the memory to implement an ionospheric STEC extraction method as described above.

[0009] In a fifth aspect, a computer readable storage medium stores at least one instruction, at least one program, a code set or an instruction set, which are loaded and executed by a processor to implement an ionospheric STEC extraction method as described above.

[0010] Compared with the prior art, the technical scheme of the present application has the following beneficial effects: By constructing an improved PPP model, modifying the receiver clock bias parameter, and adding the receiver DCB parameter to separate it from the ionospheric parameter, an uncontaminated ionospheric slant delay estimate is obtained. The new ambiguity parameter can still use the traditional phase bias product for ambiguity fixing to improve the PPP positioning accuracy and the STEC extraction accuracy. This method aims to eliminate the influence of the receiver DCB on the STEC extraction and provide unbiased STEC for subsequent ionospheric monitoring and modeling. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1A flowchart of a method for extracting ionospheric STEC in some embodiments of the present application is shown in FIG. 1. Figure 2 A module diagram of a system for extracting ionospheric STEC in some embodiments of the present application is shown in FIG. 2. DETAILED DESCRIPTION

[0012] The terms "first", "second", and the like in the description and in the claims of the present application and in the above drawings are used for distinguishing between similar objects and not necessarily for describing a specific sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the application described herein are capable of functioning in other sequences, unless explicitly claimed otherwise. Furthermore, the terms "comprise", "have" and any variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. The term "determine" broadly encompasses a wide variety of actions and, therefore, the term "determine" can include, for example, measure, evaluate, calculate, compute, process, derive, investigate, look up (e.g., in a table, a database or another data structure), discover, and the like. The term "determine" can also include receive (e.g., receive information), access (e.g., access data in a memory), and the like. The term "determine" can also include generate, create, establish, and the like. The term "determine" can also include resolve, select, choose, and the like. The term "determine" can also include other actions.

[0013] It should be noted that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or connected to the other element through an intervening element. In addition, "connected" in the following embodiments should be understood as "electrically connected", "communicatively connected", and the like if there is transmission of electrical signals or data between the connected objects.

[0014] It should be emphasized that the acquisition, transmission, storage, use, processing, and the like of data in the technical solutions of the embodiments of the present application all comply with the relevant provisions of national laws and regulations.

[0015] In the embodiments of the present application, some industry existing solutions of software, components, models, and the like may be mentioned, which should be considered as exemplary, and the purpose is only to illustrate the feasibility of the implementation of the technical solutions of the present application, but does not mean that the applicant has or will necessarily use the solutions.

[0016] The accompanying drawings are only used for illustrative description and should not be understood as a limitation on the patent; In order to better illustrate the embodiments, some components in the drawings may be omitted, enlarged or reduced, and do not represent the actual size of the product; It will be appreciated by those skilled in the art that certain known structures and their descriptions can be omitted from the drawings for the sake of clarity.

[0017] The technical solutions of the present application will be further described below in combination with the drawings and examples.

[0018] Example 1 This example provides an ionospheric STEC extraction method, referring to Figure 1 , comprising: Based on the received multi-system multi-frequency satellite observation value, a PPP observation model containing the receiver DCB parameter is constructed; The PPP observation model is measured and updated by PPP filtering to obtain the state vector and its variance-covariance matrix; The state vector and its variance-covariance matrix are fixed for ambiguity to obtain ionospheric delay; The ionospheric delay is converted into STEC.

[0019] The method constructs an improved PPP model, modifies the receiver clock bias parameter, and increases the receiver DCB parameter to separate it from the ionospheric parameter, so as to obtain the ionospheric slant delay estimate which is not contaminated; The new ambiguity parameter can still use the traditional phase bias product for ambiguity fixing to improve the PPP positioning accuracy and STEC extraction accuracy; The method aims to eliminate the influence of the receiver DCB on the STEC extraction, and provides unbiased STEC for subsequent ionospheric monitoring and modeling In some preferred embodiments, the PPP observation model containing the receiver DCB parameter is constructed, comprising: When the satellite system is a code division multiple access system, the PPP observation model is represented as:

[0020] wherein, is the pseudo-range observation value, is the carrier phase observation value; the superscript and respectively represent the satellite and the corresponding satellite system; the subscript and respectively represent the station and the signal frequency sequence number; is the signal frequency; is the satellite precise clock bias product, wherein the ionosphere-free combination of the first and second frequency pseudo-range biases , is absorbed, that is , ， ; is the distance between the satellite and the station; a reference receiver clock bias, a reference system when using multi-system observations; an inter-system bias; and a tropospheric wet delay and its mapping function, respectively; the ionospheric delay at the first frequency; a receiver differential code bias parameter; a signal wavelength; a ambiguity parameter; an observation of the sum of the remaining un-modeled errors; when the satellite system is a frequency division multiple access system GLONASS, the PPP observation model is expressed as:

[0021] i.e. setting the receiver clock bias parameter separately for each satellite and the receiver DCB parameter .

[0022] In some preferred embodiments, the inter-system bias wherein the SYS is any one of GPS, Galileo, BDS and QZSS; wherein, when the SYS is the BDS, BDS-2 and BDS-3 should be treated as two independent systems and the systematic bias of BDS-2 satellites related to satellite elevation angle is corrected by using a systematic bias correction model; when multiple satellite systems are used jointly, the ISB parameter is required for the satellite system other than the BS; the ISB parameter is not required when using single system observations; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor

[0023] ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor ; the ionospheric delay at the first frequency is converted to other frequencies by an ionospheric mapping factor correcting the station position of the at least one of the solid tide correction, the ocean tide correction, and the polar tide correction.

[0024] In some preferred embodiments, the fixing the ambiguity and the variance-covariance matrix of the state vector to obtain ionospheric slant delay comprises: fixing the ambiguity of the ultra-wide lane, the wide lane and the N1 in turn from easy to difficult; In the traditional non-difference non-combination PPP model, the form of the ambiguity parameter is: wherein, is an unknown integer ambiguity in the phase observation of the satellite s is a phase bias of the receiver on the satellite system SYS and the first k frequency; is an unknown integer ambiguity in the phase observation of the satellite k is a phase bias of the receiver on the satellite system SYS and the first frequency; s is a phase bias of the satellite k on the first frequency; k is a pseudo-range bias of the receiver on the satellite system SYS and the first frequency; s is a pseudo-range bias of the satellite k on the first frequency.

[0025] Compared with the prior art, in the method, the ambiguity parameter only the receiver pseudo-range bias part changes, and the pseudo-range bias and the phase bias related to the satellite remain unchanged, so the inter-satellite single-difference floating ambiguity constructed from the non-difference floating ambiguity is consistent with the traditional PPP model, and the traditional uncorrected phase delay (UPD) product can still be used to restore the integer characteristics of the floating ambiguity.

[0026] The floating ultra-wide lane ambiguity and the floating wide lane ambiguity can be expressed as:

[0027] wherein, is a single-difference ultra-wide lane ambiguity of the satellite and the reference satellite , and the subscripts i and j are the frequency serial numbers for constructing the ultra-wide lane ambiguity, which are selected according to the actual ultra-wide lane UPD product, and in the commonly used three-frequency observation model, i=2 and j=3; and are non-difference floating ambiguities corresponding to the frequencies, which can be obtained from the PPP filter; is an ultra-wide lane UPD product; is a single-difference ultra-wide lane ambiguity of the satellite and the reference satellite ​single-difference wide-lane ambiguity; and non-difference float ambiguity of the first frequency and the second frequency, which can be obtained from the PPP filter; wide-lane UPD product; satellite and reference star should be the same system satellite, otherwise the receiver end hardware delay cannot be completely eliminated, so each satellite system needs to select a satellite as the reference star; In this embodiment, taking three-frequency observations as an example, the float super-wide-lane ambiguity and the float wide-lane ambiguity can be expressed as: ; Since the super-wide-lane and wide-lane wavelengths are relatively long, after several epochs of filtering, the float super-wide-lane ambiguity and the float wide-lane ambiguity whose precision and decimal part threshold meet the requirements can be directly rounded to integers 、 ; Construct the virtual observation equation of the float super-wide-lane ambiguity and the float wide-lane ambiguity, update the state vector and state variance-covariance matrix, and narrow the float N1 ambiguity search space: ; In this embodiment, taking three-frequency observations as an example, the virtual observation equation of the float super-wide-lane ambiguity and the float wide-lane ambiguity is constructed, the state vector and state variance-covariance matrix are updated, and the float N1 ambiguity search space is narrowed: ; Narrow the float N1 ambiguity search space:

[0028] The float N1 ambiguity is expressed as:

[0029]

[0030]

[0031] wherein, single-difference float N1 ambiguity of satellite and reference star ; non-difference first frequency float ambiguity of satellite , which should be obtained from the filter after the super-wide-lane and wide-lane are fixed as integers; first frequency float ambiguity of reference star ; single-difference float N1 ambiguity of satellite a first frequency ambiguity UPD correction number; a reference satellite a first frequency ambiguity UPD correction number converted from narrow-lane and wide-lane ambiguity UPD products; a satellite a narrow-lane UPD product; a reference satellite a k-th frequency signal frequency; combining the N1 variance-covariance matrix in the filter, using a least-squares ambiguity decorrelation adjustment (LAMBDA) method to search for an integer fixed solution of the floating-point N1 ambiguity and calculating a Ratio value, if greater than a set threshold, considering that the ambiguity is fixed successfully, otherwise considering that the ambiguity is fixed unsuccessfully, outputting a floating-point solution; if the floating-point N1 ambiguity is successfully fixed, constructing a virtual observation equation of the floating-point N1 ambiguity:

[0032] further updating the state vector and the variance-covariance matrix to be an ambiguity fixed solution, so that the ionospheric delay .

[0033] In some preferred embodiments, the converting the ionospheric slant delay into STEC comprises: representing an integral of ionospheric electron density along a signal propagation path, and the conversion formula of the ionospheric delay is:

[0034] wherein, ; unit: meter; representing a carrier frequency of a satellite a first frequency signal, unit: Hz; unit: TECu.

[0035] Embodiment 2 This embodiment further provides an ionospheric STEC extraction system on the basis of Embodiment 1, referring to Figure 2 , comprising: an observation model construction module, configured to construct a PPP observation model containing the receiver DCB parameter based on the received multi-system multi-frequency satellite observation value; An observation model updating module is configured to perform measurement updating on the PPP observation model by PPP filtering to obtain a state vector and a variance-covariance matrix thereof; An ambiguity fixing module is configured to perform ambiguity fixing on the state vector and the variance-covariance matrix thereof to obtain ionospheric delay; An STEC conversion module is configured to convert the ionospheric delay into STEC.

[0036] The system constructs an improved PPP model, modifies a receiver clock bias parameter, and adds a receiver DCB parameter to separate the ionospheric parameter, thereby obtaining uncontaminated ionospheric slant delay estimates. New ambiguity parameters can still use traditional phase bias products for ambiguity fixing to improve the PPP positioning accuracy and the STEC extraction accuracy. The system aims to eliminate the influence of the receiver DCB on the STEC extraction and provide unbiased STEC for subsequent ionospheric monitoring and modeling.

[0037] It can be understood that the system of the embodiment corresponds to the method of the above-mentioned embodiment 1, and the optional items in the above-mentioned embodiment 1 are also applicable to the embodiment, and thus are not repeated here.

[0038] Embodiment 3 The embodiment provides a computer readable storage medium, and at least one instruction, at least one program, a code set or an instruction set are stored on the storage medium. The at least one instruction, at least one program, code set or instruction set are loaded and executed by a processor, so that the processor executes part or all steps of the method provided in the embodiment 1.

[0039] It can be understood that the storage medium can be transitory or non-transitory. Exemplarily, the storage medium includes, but is not limited to, a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0040] Exemplarily, the processor can be a central processing unit (CPU), a microprocessor unit (MPU), a digital signal processor (DSP) or a field programmable gate array (FPGA).

[0041] Exemplarily, the read-only memory includes but is not limited to a MASK ROM, a PROM, an EPROM, an EEPROM, a Flash, and the like.

[0042] Exemplarily, the random access memory includes but is not limited to a DRAM, a SRAM, a SDRAM, a DDR SDRAM, and the like.

[0043] In some examples, a computer program product is provided, which can be implemented in a hardware manner, a software manner, or a combination of both. As a non-limiting example, the computer program product can be embodied in a storage medium, and can also be embodied in a software product, such as an SDK (Software Development Kit) or the like.

[0044] As a non-limiting example, a computer program product is provided, which includes a computer program or computer executable instructions stored in a computer readable storage medium. A processor of an electronic device reads the computer program or computer executable instructions from the computer readable storage medium, and the processor executes the computer executable instructions, so that the electronic device performs part or all of the steps of the method described in the embodiments of the present application.

[0045] In some examples, a computer program is provided, which includes computer readable code, and when the computer readable code runs in a computer device, a processor in the computer device performs part or all of the steps of the method.

[0046] The embodiments also provide an electronic device, which includes a memory and a processor. The memory stores at least one instruction, at least one program, a code set, or an instruction set. When the processor executes the at least one instruction, at least one program, code set, or instruction set, part or all of the steps of the method described in Embodiment 1 are implemented.

[0047] In some examples, a hardware entity of the electronic device is provided, comprising: a processor, a memory and a communication interface; wherein the processor generally controls the overall operation of the electronic device; the communication interface is used for the electronic device to communicate with other terminals or servers through a network; the memory is configured to store instructions and applications executable by the processor, and can also cache data to be processed by the processor and data processed or to be processed by each module in the electronic device (including but not limited to image data, audio data, voice communication data and video communication data), which can be realized by FLASH, EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory) or RAM (Random Access Memory).

[0048] The processor can include one or more processing elements. Thus, the processor can include one or more integrated circuits (ICs) that are configured to perform the functions of the processor. In addition, each integrated circuit can include circuitry (e.g., first circuitry, second circuitry, and other circuitry, etc.) that is configured to perform the functions of the processor.

[0049] Further, the processor, the communication interface and the memory can transmit data through a bus, which can include any number of interconnected buses and bridges, connecting the various circuitry of the one or more processors and the memory together.

[0050] It can be understood that the optional items in Embodiment 1 described above are also applicable to this embodiment, and thus will not be repeated here.

[0051] The same or similar reference numerals correspond to the same or similar components; The terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present application; It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0052] In different specific implementations, the methods or systems described in the present application can be implemented in software, hardware or their combination. In addition, the order of the steps of the method can be changed, and various elements can be added, reordered, combined, omitted, modified, etc.

[0053] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation of the present application, and are not used to limit the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art, and each separate structure / function module or unit can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part, and the structure and function of the separate components can be realized as a combined structure or component. Here, all the implementations are not required or possible to be exhausted. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for extracting STEC from the ionosphere, characterized in that, include: Based on the received multi-system, multi-frequency satellite observations, a PPP observation model including receiver DCB parameters is constructed. The PPP observation model is updated by PPP filtering to obtain the state vector and its variance-covariance matrix. By fixing the ambiguity of the state vector and its variance-covariance matrix, the ionospheric delay is obtained; The ionospheric delay is converted into STEC.

2. The method for extracting STEC from the ionosphere according to claim 1, characterized in that, The construction of the PPP observation model, which includes the receiver's DCB parameters, based on the received multi-system, multi-frequency satellite observations, includes: When the satellite system is a code division multiple access system, the PPP observation model is expressed as: in, These are pseudorange observations. Carrier phase observations; superscript and These represent the satellite and its corresponding satellite system; subscript and These represent the station and signal frequency serial numbers, respectively. The signal frequency; This is a satellite precision clock product that incorporates pseudorange biases from both the first and second frequencies. , The non-ionized combination, i.e. , , ; The distance between the satellite and the station; , is the reference receiver clock bias. As a reference system when using observations from multiple systems; This represents the inter-system deviation; and These are the tropospheric wet delay and its projection function, respectively; The ionospheric delay is the amount of time required to reach the first frequency. This refers to the receiver differential code offset parameter; The wavelength of the signal; , is the ambiguity parameter; The observed values ​​represent the sum of the remaining unmodeled errors; When the satellite system is a frequency division multiple access system GLONASS, the PPP observation model is expressed as: That is, the receiver clock bias parameter is set individually for each satellite. and the parameters of the receiver DCB .

3. The method for extracting STEC from the ionosphere according to claim 2, characterized in that, Inter-system deviation In this context, SYS refers to any one of GPS, Galileo, BDS, and QZSS systems. Wherein, when SYS is BDS, BDS-2 and BDS-3 are treated as two independent systems, and the systematic deviation of BDS-2 satellite related to satellite elevation angle is corrected by using a systematic deviation correction model; When multiple satellite systems are used in conjunction, the ISB parameter needs to be set for all satellite systems except the BS; when using single-system observations, the ISB parameter is not required. Through ionospheric mapping factor The ionospheric delay amount at the first frequency Switch to other frequencies; By setting the receiver differential code deviation parameter for all frequencies except the first frequency pseudorange observation value. To estimate the receiver DCB; The observed values ​​of the sum of the remaining unmodeled errors This includes at least one of measurement noise, gross error, and multipath error.

4. The method for extracting STEC from the ionosphere according to claim 3, characterized in that, The pseudorange observations are corrected using at least one of the following methods: satellite DCB product correction, tropospheric dry delay model correction, antenna correction, relativistic correction, phase wrapping correction, and multi-frequency data IFCB correction. and the carrier phase observation value Make corrections; By using at least one of solid tide correction, ocean tide correction, and polar tide correction, the aforementioned The location of the measuring station was corrected.

5. The method for extracting STEC from the ionosphere according to claim 4, characterized in that, The step of fixing the ambiguity of the state vector and its variance-covariance matrix to obtain the ionospheric slant delay includes: The floating-point ultrawide ambiguity and floating-point wide-lane ambiguity can be expressed as: in, For satellite and reference star The single-difference ultra-wide lane ambiguity, where the subscripts i and j are the frequency indices for constructing the ultra-wide lane ambiguity, selected according to the actual ultra-wide lane UPD product; and The non-difference floating-point ambiguity corresponding to the frequency can be obtained from the PPP filter; For ultra-wide lane UPD products; For satellite and reference star Single-difference wide-lane ambiguity; and The non-difference floating-point ambiguity for the first and second frequencies can be obtained from the PPP filter; For wide-lane UPD products; satellite and reference star The satellites should be from the same system; otherwise, the hardware delay at the receiver cannot be completely eliminated. Therefore, each satellite system needs to select a satellite as a reference satellite. The floating-point ultrawide ambiguity and the floating-point wide-lane ambiguity, which meet the requirements for precision and decimal part thresholds, are rounded and fixed to integers. , ; Construct virtual observation equations for the floating-point ultrawide ambiguity and the floating-point wide-lane ambiguity, update the state vector and state variance-covariance matrix, and reduce the floating-point N1 ambiguity search space: The floating-point N1 ambiguity is represented as follows: in, For satellite and reference star The single-difference floating-point N1 ambiguity; For satellite The non-difference first-frequency floating-point ambiguity should be obtained from the filter after the ultra-wide lane and wide lane are fixed to integers. As a reference star The first frequency floating-point ambiguity; For satellite The first frequency ambiguity UPD correction number; As a reference star The first frequency ambiguity UPD correction number; the first frequency ambiguity UPD correction number is derived from the narrow alley and wide alley ambiguity UPD products; For satellite Narrow alley UPD products; As a reference star The frequency of the k-th frequency signal; By combining the N1 variance-covariance matrix in the filter, the least squares downcorrelation adjustment method is used to search for the integer fixed solution of the floating-point N1 ambiguity. It calculates the Ratio value; if it is greater than the set threshold, the ambiguity is considered to have been successfully fixed; otherwise, it is considered to have failed, and a floating-point solution is output. If the floating-point N1 ambiguity is successfully fixed, construct the virtual observation equation for the floating-point N1 ambiguity: Further updating the state vector and variance-covariance matrix yields the fixed ambiguity solution, from which the ionospheric delay can be obtained. .

6. The method for extracting STEC from the ionosphere according to claim 5, characterized in that, The process of converting the ionospheric slant delay to STEC includes: This represents the integral of the ionospheric electron density along the signal propagation path, and the ionospheric delay. The conversion formula is: in, ; The unit is meters; Indicates satellite The carrier frequency of the first frequency signal is expressed in Hz. The unit is TECu.

7. A system for extracting STEC from the ionosphere, characterized in that, include: The observation model construction module is used to construct a PPP observation model containing the receiver DCB parameters based on the received multi-system multi-frequency satellite observation values. The observation model update module is used to update the PPP observation model through PPP filtering to obtain the state vector and its variance-covariance matrix; The ambiguity fixing module is used to fix the ambiguity of the state vector and its variance-covariance matrix to obtain the ionospheric delay. The STEC conversion module is used to convert the ionospheric delay into STEC.

8. A computer program product, comprising a computer program or computer-executable instructions, characterized in that, When the computer program or computer-executable instructions are executed by a processor, the method described in any one of claims 1-6 is implemented.

9. An electronic device, characterized in that, include: Memory is used to store executable instructions or computer programs. A processor, configured to execute computer-executable instructions or computer programs stored in the memory, implements the method according to any one of claims 1-6.

10. A computer-readable storage medium, characterized in that, The storage medium stores at least one instruction, at least one program, code set, or instruction set, which is loaded and executed by a processor to implement the method as described in any one of claims 1-6.

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