A real-time PPP-RTK signal deviation product integrity monitoring method

Abstract

The present application relates to a kind of real-time PPP-RTK signal deviation product integrity monitoring method, comprising: S1) receiving the real-time multi-frequency observation data of monitoring station and generating real-time satellite clock track correction product and signal deviation product;S2) based on ionosphere-free combination extraction corresponding frequency point's equivalent space signal ranging residual error, obtain the equivalent space signal ranging residual error corresponding to all frequency point combination mode;S3) establish the residual error hypothesis testing model under fault and no fault;S4) the detection statistic and detection threshold of signal deviation product integrity monitoring are constructed, and detection statistic and detection threshold are compared to carry out fault detection, if the detection result is no fault, then enter step S5, if the detection result is fault, then enter step S6;S5) calculate minimum detectable deviation, execute availability judgment;S6) according to fault detection result and availability judgment result, determine the final alarm information of the signal deviation product of different frequency points.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of satellite navigation technology, in particular to a real-time PPP-RTK signal bias product integrity monitoring method. BACKGROUND

[0002] Global Navigation Satellite System (GNSS) has powerful functions such as navigation, positioning, and timing, and is an important means to help realize the informatization and modernization of transportation, covering multiple typical application scenarios such as sea, land, and air, and is widely used in transportation, military, agriculture, and other fields, such as automatic landing of aircraft, automatic landing of carrier-based aircraft, vehicle navigation system, unmanned driving, intelligent traffic control, intelligent ocean operation, and intelligent agricultural cooperative operation, etc.

[0003] Precise Point Positioning Real-time Kinematic (PPP-RTK) is a hot research topic in the field of satellite navigation. PPP-RTK user terminal relies on satellite orbit, satellite clock error, signal bias, code bias, regional troposphere, and regional ionosphere correction products provided by the cloud master station to complete positioning convergence within 1 minute and achieve centimeter-level positioning accuracy. The positioning accuracy of PPP-RTK is sufficient to meet the positioning needs of intelligent and few-person application scenarios such as automatic driving and precision agriculture. However, since intelligent and few-person application scenarios often involve life safety-related applications, in addition to the requirement for positioning accuracy, the reliability of navigation and positioning must also be ensured.

[0004] Signal bias product is a prerequisite for PPP-RTK to complete ambiguity fixing and achieve high-precision fast-convergence positioning. Faults in signal bias products will inevitably affect the reliability of PPP-RTK navigation and positioning. Signal bias products are estimated based on global observation station network data and real-time satellite clock and orbit correction products. Influenced by factors such as observation station data faults, satellite clock and orbit correction product inaccuracies, and signal bias product estimation model faults, the integrity of real-time satellite signal bias products is difficult to guarantee, resulting in reduced reliability of PPP-RTK navigation and positioning and restricting the application of PPP-RTK technology in intelligent and unmanned scenarios. SUMMARY

[0005] To solve the above problems and ensure the integrity of real-time PPP-RTK signal bias products, the present application proposes a real-time PPP-RTK signal bias product integrity monitoring method, which comprises:

[0006] Step S1) The PPP-RTK cloud master station receives real-time multi-frequency observation data of the monitoring station and generates real-time satellite clock and orbit correction products and signal bias products using satellite data provided by the reference station, which are used as input data for real-time PPP-RTK signal bias product integrity monitoring;

[0007] Step S2) extracts the equivalent space signal ranging residual of the corresponding frequency point based on the ionosphere-free combination, traverses different frequency point combination modes, obtains the equivalent space signal ranging residual corresponding to all frequency point combination modes, and classifies them, wherein the ranging residual of all frequency point combinations involving the use of the same frequency point signal deviation product is classified into a class;

[0008] Step S3) uses all the equivalent space signal ranging residuals corresponding to different frequency point combinations obtained in step S2 to establish a residual hypothesis test model under the fault and non-fault conditions;

[0009] Step S4) constructs a detection statistic for real-time satellite signal deviation product integrity monitoring, establishes the residual hypothesis test model under the non-fault condition according to step S3, and constructs a detection threshold combining the continuity risk required by the real-time satellite clock and orbit correction product and the signal deviation product, compares the detection statistic with the detection threshold to perform fault detection, if the detection result is non-fault, it enters step S5, if the detection result is fault, it enters step S6;

[0010] Step S5) uses the residual hypothesis test model under the fault condition established in step S3, and combines the integrity risk required by the real-time satellite clock and orbit correction product and the signal deviation product to calculate the minimum detectable deviation, and performs availability judgment;

[0011] Step S6) determines the final alarm information of the signal deviation product of different frequency points according to the signal deviation product fault detection result executed in step S4 and the signal deviation product availability judgment result executed in step S5.

[0012] The beneficial effects of the present application are:

[0013] The real-time PPP-RTK signal deviation product integrity monitoring method provided by the present application relies on the independent multi-frequency observation data of the monitoring station, extracts the equivalent space signal ranging residual based on the ionosphere-free combination, uses the frequency correlation characteristics of the signal deviation product, identifies the satellite clock and orbit correction product and the signal deviation product fault through the multi-frequency point arrangement combination and the classification processing of the equivalent space signal ranging residual, completes the fault detection and availability judgment of the real-time signal deviation product in the PPP-RTK cloud master station, determines the final alarm information of the satellite clock and orbit correction product and the signal deviation product of each frequency point, and guarantees the integrity of the signal deviation product broadcast by the PPP-RTK cloud master station, provides a solution for the landing application of the PPP-RTK technology to the intelligent and unmanned application scenarios with high integrity requirements, and has important significance. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 A flowchart of a real-time PPP-RTK signal deviation product integrity monitoring method provided by the present application. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0016] The real-time PPP-RTK signal bias product integrity monitoring method provided by the present application is completed at a PPP-RTK cloud master station.

[0017] Reference Figure 1 The real-time PPP-RTK signal bias product integrity monitoring method comprises the following steps.

[0018] Step S1) The PPP-RTK cloud master station receives real-time multi-frequency observation data of a monitoring station and generates real-time satellite clock and orbit correction products and signal bias products using satellite data provided by a reference station, which are used as input data for real-time PPP-RTK signal bias product integrity monitoring. The real-time satellite clock and orbit correction products include real-time precise satellite orbit products and real-time satellite clock error products.

[0019] The real-time multi-frequency observation data of the monitoring station needs to be independent of the real-time satellite clock and orbit correction products and the signal bias products, that is, the real-time multi-frequency observation data of the monitoring station cannot be used to generate the real-time satellite clock and orbit correction products and the signal bias products. The PPP-RTK cloud master station uses satellite data provided by the reference station to generate the real-time satellite clock and orbit correction products and the signal bias products.

[0020] The stations used in the real-time service process can be divided into reference stations and monitoring stations. In the present application, satellite data provided by the reference stations are used to generate real-time satellite clock and orbit correction products and signal bias products, and data provided by the monitoring stations are used for integrity monitoring of the real-time PPP-RTK signal bias products in the present application. In the present application, the observation data used cannot be used both to generate the satellite clock and orbit correction products and the signal bias products and to verify the integrity of the signal bias products, otherwise the integrity verification result of the products will be inaccurate. Therefore, the real-time multi-frequency observation data provided by the monitoring station does not participate in the generation of the real-time satellite clock and orbit correction products and the signal bias products, but satellite data provided by the reference station are used to generate the real-time satellite clock and orbit correction products and the signal bias products.

[0021] The input data for real-time PPP-RTK signal bias product integrity monitoring include received real-time multi-frequency observation data and generated real-time satellite clock and orbit correction products and signal bias products.

[0022] Step S2) extracting the equivalent space signal ranging residuals of the corresponding frequency points based on the ionosphere-free combination, traversing different frequency point combination modes, obtaining the equivalent space signal ranging residuals corresponding to all frequency point combination modes and classifying, wherein the ranging residuals of the signal bias products of all frequency point combinations involving the use of the same frequency point are classified into a class.

[0023] Using the received observation data of the monitoring station and the real-time satellite clock and orbit correction products and signal bias products generated using the satellite data provided by the reference station, the ranging residuals of the equivalent space signal corresponding to frequency point i and frequency point j are extracted based on the ionosphere-free combination:

[0024]

[0025] In formula (1), the superscript k represents the satellite, the subscript m represents the monitoring station, the subscript ij represents the combination of frequency point i and frequency point j, and the subscript IF represents the ionosphere-free combination, represents the ranging residuals of the equivalent space signal corresponding to the combination of frequency point i and frequency point j, represents the carrier phase observation of the ionosphere-free combination after being corrected by the real-time satellite signal bias product, X IMS,m represents the position of the monitoring station m, represents the satellite position after being corrected by the real-time precise satellite orbit product, c is the speed of light, Δt IMS,m is the receiver clock error of the monitoring station m, is the satellite clock error after being corrected by the real-time satellite clock error product, Z w is the wet delay of the troposphere, H(·) is the tropospheric wet delay mapping function, θ k is the satellite elevation angle, is the ambiguity corresponding to the ionosphere-free combination.

[0026] It should be noted that since the real-time satellite clock and orbit correction product error and the signal bias product error are coupled with each other, the constructed equivalent space signal ranging residuals not only contain the signal bias product error but also contain the real-time satellite clock and orbit correction product error.

[0027] After extracting the equivalent space signal ranging residuals corresponding to frequency point i and frequency point j based on the ionosphere-free combination, the combination mode of frequency point i and frequency point j is modified, and the operation of equation (1) is repeatedly performed, so as to traverse different frequency point combination modes and obtain all the equivalent space signal ranging residuals corresponding to all the frequency point combination modes of the monitoring station. After completing the traversal of all the frequency point combination modes and obtaining the corresponding all the equivalent space signal ranging residuals, all the equivalent space signal ranging residuals are classified, wherein the ranging residuals of the signal bias products of all the frequency point combinations involving the use of the same frequency point are classified into a class:

[0028]

[0029] wherein is a set of ranging residuals of signal bias products corresponding to satellite k and frequency point a, represents a ranging residual of an equivalent space signal of frequency point a, represents a ranging residual of an equivalent space signal corresponding to the combination of frequency point i and frequency point j; k represents a satellite, a represents a frequency point, m represents a monitoring station, and M is a set of all monitoring stations.

[0030] As can be seen from equation (2), for satellite k, as long as one of the frequency points i or j in the combination of frequency point i and frequency point j is frequency point a, the ranging residual of the equivalent space signal corresponding to the combination of frequency point i and frequency point j is classified into a category, i.e. belongs to set

[0031] Step S3) uses all the ranging residuals of the equivalent space signals corresponding to different combinations of frequency points obtained in step S2 to establish a residual hypothesis test model under the fault and non-fault conditions.

[0032] The ranging residuals of the equivalent space signals obtained in step S2 contain real-time satellite clock and orbit correction products and signal bias products, and the ranging residuals of the equivalent space signals can be used to construct a detection statistic of the real-time satellite signal bias product. Assuming that the ranging residuals of the equivalent space signals under the fault and non-fault conditions respectively follow Gaussian distributions with zero mean and non-zero mean, the residual hypothesis test model under the fault and non-fault conditions is:

[0033]

[0034] wherein H0 represents a non-fault mode hypothesis, H1 represents a fault mode hypothesis, and μ is a ranging bias existing under the fault mode; represents a ranging residual of an equivalent space signal corresponding to the combination of frequency point i and frequency point j; is a standard deviation corresponding to the ranging residual of the equivalent space signal corresponding to the combination of frequency point i and frequency point j, which can be represented as a linear superposition of a real-time satellite clock and orbit correction product quality identifier a signal bias product quality identifier and a measurement noise standard deviation , and is specifically:

[0035]

[0036] wherein the real-time satellite clock and orbit correction product quality identifier QI URA and the signal bias product quality identifier QI Bias,ij are obtained through real-time broadcasting of a PPP-RTK cloud master station, and the measurement noise standard deviation σ δ,ijThe measurement noise standard deviation σ can be obtained by empirical elevation angle model weighting.

[0037] Herein, the real-time satellite clock and orbit correction product quality identifier QI URA The signal bias product quality identifier QI Bias,ij is obtained by existing known processing methods before performing the real-time PPP-RTK signal bias product integrity monitoring method, and the measurement noise standard deviation σ δ,ij is obtained by empirical elevation angle model weighting.

[0038] Step S4) constructing a detection statistic of real-time satellite signal bias product integrity monitoring, constructing a detection threshold according to the residual hypothesis test model under the fault-free condition established in step S3 and combining the continuity risk required by the real-time satellite clock and orbit correction product and the signal bias product, comparing the detection statistic with the detection threshold to perform fault detection, if the detection result is fault-free, entering step S5, and if the detection result is faulty, entering step S6.

[0039] The method for constructing the detection statistic of real-time satellite signal bias product integrity monitoring is as follows:

[0040]

[0041] wherein represents the detection statistic of the real-time satellite signal bias product for satellite k and frequency point a, is a set of ranging residuals of the signal bias product corresponding to satellite k and frequency point a, represents the ranging residual of the equivalent space signal of frequency point a, represents the standard deviation corresponding to the ranging residual of the equivalent space signal of frequency point a.

[0042] According to the residual hypothesis test model established based on equation (3), the detection statistic under the fault-free condition is subject to a central chi-square distribution with a degree of freedom P, and the detection threshold is calculated by combining the continuity risk required by the real-time satellite clock and orbit correction product and the signal bias product as follows:

[0043]

[0044] wherein CR is the required continuity risk; N S is the number of available satellites; is the detection threshold for satellite k and frequency point a; f(x) is the probability density function, and then represents the probability density function of the chi-square distribution, wherein x is the independent variable, P is the degree of freedom, and the value of P is the number of elements in the set .

[0045] Since the required continuity risk CR is given in advance, the corresponding detection threshold can be calculated by equation (6):

[0046] Comparative test statistics and detection threshold Since the constructed detection statistic contains the signal bias product error and the real-time satellite clock orbit correction product error, if the detection statistic Less than the detection threshold The test result indicates that the real-time satellite clock orbit correction product corresponding to satellite k and the signal deviation product corresponding to frequency a are normal, and the process goes to step S5. If the test statistic Greater than or equal to the detection threshold The test result indicates that the real-time satellite clock and orbit correction product corresponding to satellite k is faulty and / or the signal deviation product corresponding to frequency a is faulty, and the process proceeds to step S6. During the fault detection process, the presence or absence of a fault can be marked, that is, the corresponding product can be marked as faulty or not.

[0047] Step S5) Using the residual hypothesis test model established in step S3 under fault conditions, and combining the integrity risk required by the real-time satellite clock and orbit correction products and the signal deviation products, the minimum detectable deviation is calculated and the availability judgment is performed.

[0048] According to the residual hypothesis test model established based on equation (3), the detection statistic in the case of a fault follows a non-central chi-square distribution with P degrees of freedom. Combined with the integrity risk required by the real-time satellite clock and orbit correction product and the signal bias product, the corresponding missed detection rate in the case of a fault is calculated as:

[0049]

[0050] Among them, P MD is the missed detection rate, which is the preset value, IR is the required integrity risk, N S is the number of available satellites, P f is the priori failure probability of the real-time satellite clock and orbit correction product and the signal bias product, which is a known value; is the detection threshold for satellite k and frequency a; f(x) is the probability density function, then Represents the probability density function of the chi-square distribution, where x is the independent variable, P is the degree of freedom, and the value of P is the set The number of elements in , is the non-centralized parameter corresponding to satellite k and frequency a.

[0051] Since the missed detection rate P is given in advance MDand the required integrity risk IR, the non-centralized parameter corresponding to satellite k and frequency a can be calculated from equation (7): From this, the corresponding minimum detectable deviation MDB can be calculated as:

[0052]

[0053] in It represents the minimum detectable deviation corresponding to satellite k and frequency point a.

[0054] Comparing Minimum Detectable Deviation and the preset fault detection sensitivity alarm limit AL MDB If the minimum detectable deviation Less than the preset fault detection sensitivity alarm limit AL MDB , then the monitoring results of the real-time satellite clock orbit correction product corresponding to the marked satellite k and the signal deviation product corresponding to the frequency point a are available; if the minimum detectable deviation Greater than or equal to the preset fault detection sensitivity alarm limit AL MDB , then the monitoring results of the real-time satellite clock orbit correction product corresponding to satellite k and the signal deviation product corresponding to frequency point a are marked as unavailable; go to step S6.

[0055] Step S6) According to the fault detection result performed in step S4 and the availability judgment result performed in step S5, the final alarm information of the signal deviation products at different frequency points is determined.

[0056] Based on the information introduced in step S2: the real-time satellite clock and orbit correction product error and the signal bias product error are coupled with each other, and the equivalent space signal ranging residual contains the signal bias product error and the real-time satellite clock and orbit correction product error. It can be understood that in step S6, in addition to being able to determine the final alarm information of the signal bias product at different frequencies, the final alarm information of the real-time satellite clock and orbit correction product can also be determined.

[0057] The execution method of step S6 is: counting the number of faulty results and unavailable results in the fault detection results and availability judgment results, and determining the final alarm information of the real-time satellite clock and orbit correction product and the satellite signal deviation product at different frequencies based on the statistical number.

[0058] Specifically, if the fault detection result is no fault and the availability judgment result is available, the real-time satellite clock orbit correction product and the signal deviation product of the corresponding frequency point will be processed normally, that is, the alarm information will be marked as normal, and the Boolean alarm flag bit bool ais set to "0" to indicate; otherwise, if the fault detection result is fault and / or the availability judgment result is unavailable, the real-time satellite clock and orbit correction product or the signal deviation product of the corresponding frequency point is processed as an alarm, that is, the alarm information is marked as a fault alarm, and the Boolean alarm flag bool a is set to "1" to indicate.

[0059] The alarm information corresponding to all frequency points is integrated to construct a Boolean detection statistic ξ as follows:

[0060]

[0061] wherein ξ is a Boolean detection statistic, N f is the number of available frequency points, a represents a frequency point, and bool a represents the Boolean alarm flag of the frequency point a.

[0062] The Boolean detection statistic ξ is compared with the number of available frequency points N f to determine whether the real-time satellite clock and orbit correction product is faulty and whether the signal deviation product is faulty. If the Boolean detection statistic ξ is less than the number of available frequency points N f and not equal to 0, it indicates that the signal deviation product of the corresponding frequency point is faulty, while the real-time satellite clock and orbit correction product is not faulty; if the Boolean detection statistic ξ is equal to the number of available frequency points N f , it indicates that the real-time satellite clock and orbit correction product is faulty, while the signal deviation product of the corresponding frequency point is not faulty; if the Boolean detection statistic ξ is equal to 0, it indicates that the real-time satellite clock and orbit correction product and the signal deviation product are both not faulty, and the corresponding determination result is marked in the alarm information.

[0063] The final alarm information is broadcast to the PPP-RTK users in the service area, and the final alarm information includes: the real-time satellite clock and orbit correction product is normal or fault alarm, and the signal deviation product is normal or fault alarm, reminding the user not to use the faulty product, that is, not to use the faulty real-time satellite clock and orbit correction product and the faulty signal deviation product.

[0064] The above is a further detailed description of the present application in combination with specific embodiments, and cannot be regarded as limiting the specific embodiments of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be regarded as falling within the protection scope determined by the claims submitted by the present application.

Claims

1. A method for monitoring integrity of real-time PPP-RTK signal bias products, comprising: Step S1) receiving real-time multi-frequency observation data of a monitoring station by a PPP-RTK cloud master station and generating real-time satellite clock and orbit correction products and signal bias products by using satellite data provided by a reference station, which are input data for monitoring integrity of real-time PPP-RTK signal bias products; Step S2) extracting equivalent space signal ranging residuals of corresponding frequency points based on ionosphere-free combinations, traversing different frequency point combination modes, obtaining equivalent space signal ranging residuals corresponding to all frequency point combination modes and classifying, wherein ranging residuals of signal bias products involving using the same frequency point in all frequency point combinations are classified into one category; Step S3) establishing residual hypothesis test models under fault and non-fault conditions by using all equivalent space signal ranging residuals corresponding to different frequency point combinations obtained in Step S2; Step S4) constructing a detection statistic for monitoring integrity of real-time satellite signal bias products, constructing a detection threshold according to the residual hypothesis test model under non-fault condition established in Step S3 and combining continuity risk required by real-time satellite clock and orbit correction products and signal bias products, comparing the detection statistic and the detection threshold to perform fault detection, if the detection result is non-fault, entering Step S5, if the detection result is fault, entering Step S6; Step S5) calculating the minimum detectable bias by using the residual hypothesis test model under fault condition established in Step S3 and combining integrity risk required by real-time satellite clock and orbit correction products and signal bias products, and performing availability judgment; Step S6) determining final alarm information of real-time satellite clock and orbit correction products and signal bias products of different frequency points according to the fault detection result of whether there is fault performed in Step S4 and the availability judgment result performed in Step S5, specifically including: If the fault detection result is no fault and the availability judgment result is available, the Boolean alarm flag bool a is set to "0" to indicate; if the fault detection result is fault or the availability judgment result is unavailable, the Boolean alarm flag bool a is set to "1" to indicate; and the Boolean detection statistics is constructed as follows: Wherein ξ is a Boolean detection statistic, N f is the number of available frequency points, a represents a frequency point, bool a represents a Boolean alarm flag for frequency point a; comparing the Boolean detection statistic and the number of available frequency points to determine whether the real-time satellite clock and orbit correction products are faulty and whether the signal bias products are faulty: if the Boolean detection statistic is less than the number of available frequency points and not equal to 0, it means that the signal bias products of the corresponding frequency points are faulty, while the real-time satellite clock and orbit correction products are not faulty; if the Boolean detection statistic is equal to the number of available frequency points, it means that the real-time satellite clock and orbit correction products are faulty, while the signal bias products of the corresponding frequency points are not faulty; if the Boolean detection statistic is equal to 0, it means that the real-time satellite clock and orbit correction products and the signal bias products are all not faulty; the corresponding determination result is marked in the final alarm information. The real-time satellite clock and orbit correction products include real-time precise satellite orbit products and real-time satellite clock error products, and the received real-time multi-frequency observation data of the monitoring station does not participate in the generation of the real-time satellite clock and orbit correction products and the signal bias products.

2. The real-time PPP-RTK signal bias product integrity monitoring method of claim 1, wherein: In Step S2, the method for extracting equivalent space signal ranging residuals of corresponding frequency points based on ionosphere-free combinations is:

3. The real-time PPP-RTK signal bias product integrity monitoring method of claim 1, wherein: In Step S2, the method for classifying ranging residuals of signal bias products involving using the same frequency point in all frequency point combinations is: where the superscript k denotes the satellite, the subscript m denotes the monitoring station, the subscript ij represents the combination of frequency i and frequency j, and the subscript IF denotes the ionosphere-free combination, represents the ranging residual of the equivalent space signal corresponding to the combination of frequency i and frequency j, represents the carrier phase observation of the ionosphere-free combination after being corrected by the real-time satellite signal bias product, X IMS,m represents the position of the monitoring station m, represents the satellite position after being corrected by the real-time precise satellite orbit product, c is the speed of light, and Δt IMS,m is the receiver clock error of the monitoring station m, is the satellite clock error after being corrected by the real-time satellite clock error product, Z w is the tropospheric wet delay, H(·) is the tropospheric wet delay mapping function, and θ k is the satellite elevation angle, is the ambiguity corresponding to the ionosphere-free combination.

4. The real-time PPP-RTK signal bias product integrity monitoring method of claim 1, wherein: ​ wherein is a set of ranging residuals for signal bias products corresponding to satellite k and frequency a, represents a ranging residual for the equivalent spatial signal of frequency a, represents a ranging residual for the equivalent spatial signal corresponding to the combination of frequency i and frequency j; k represents a satellite, a represents a frequency, m represents a monitoring station, and M is a set of all monitoring stations.

5. The real-time PPP-RTK signal bias product integrity monitoring method of claim 1, wherein: In step S3, the established residual hypothesis test model under the fault and non-fault conditions is: wherein H0 represents a fault-free mode hypothesis, H1 represents a fault mode hypothesis; μ is the ranging bias existing in the fault mode; represents the ranging residual of the equivalent space signal corresponding to the combination of frequency point i and frequency point j; is the standard deviation corresponding to the ranging residual of the equivalent space signal corresponding to the combination of frequency point i and frequency point j, and the standard deviation is represented as the real-time satellite clock and orbit correction product quality identifier signal bias product quality identifier and the measurement noise standard deviation is a linear superposition, specifically: The real-time satellite clock and orbit correction product quality identifier The signal bias product quality identifier The measurement noise standard deviation is obtained by real-time broadcasting through a PPP-RTK cloud master control station Obtained by empirical elevation angle model weighting.

6. The real-time PPP-RTK signal bias product integrity monitoring method of claim 1, wherein: In step S4, the method for constructing the detection statistic of the real-time satellite signal bias product integrity monitoring is as follows: wherein denotes the detection statistic for the real-time satellite signal bias product for satellite k and frequency a, is the set of ranging residuals for the signal bias product for satellite k and frequency a, denotes the ranging residuals for the equivalent space signal for frequency a, denotes the standard deviation corresponding to the equivalent space signal ranging residuals for frequency a; The method for constructing the detection threshold is: where CR is the required continuity risk, N S is the number of available satellites, is the detection threshold for satellite k and frequency bin a, denotes the probability density function of the chi-squared distribution with x as the argument and P as the degrees of freedom.

7. The real-time PPP-RTK signal bias product integrity monitoring method of claim 6, wherein: In step S4, the specific method for comparing the detection statistic with the detection threshold for fault detection is: The size of the detection statistic and the detection threshold is compared, if the detection statistic is less than the detection threshold, the detection result indicates that the real-time satellite clock and orbit correction product corresponding to the satellite k and the signal bias product corresponding to the frequency point a are fault-free; if the detection statistic is greater than or equal to the detection threshold, the detection result indicates that the real-time satellite clock and orbit correction product corresponding to the satellite k and / or the signal bias product corresponding to the frequency point a are faulty.

8. The real-time PPP-RTK signal bias product integrity monitoring method of claim 6, wherein: In step S5, the method for obtaining the minimum detectable bias is: wherein denotes the minimum detectable bias for satellite k and frequency a, is the uncentered parameter for satellite k and frequency a; A method of obtaining non-centralized parameters is: where P MD is the probability of missing detection, IR is the required integrity risk, N S is the number of available satellites, P f is the a priori probability of failure of the real-time satellite clock and orbit correction products and signal bias products, is the detection threshold for satellite k and frequency a, denotes the probability density function of the chi-squared distribution with x as the argument and P as the degrees of freedom, is the non-centrality parameter for satellite k and frequency a; The method for performing the availability judgment is: The size of the minimum detectable bias and the preset fault detection sensitivity alarm limit is compared, if the minimum detectable bias is less than the fault detection sensitivity alarm limit, the monitoring result of the real-time satellite clock and orbit correction product corresponding to the satellite k and the signal bias product corresponding to the frequency point a is marked as available; If the minimum detectable bias is greater than or equal to the fault detection sensitivity alarm limit, the monitoring result of the real-time satellite clock and orbit correction product corresponding to the satellite k and the signal bias product corresponding to the frequency point a is marked as unavailable.

9. The real-time PPP-RTK signal bias product integrity monitoring method of claim 1, further comprising: The final alarm information is broadcast to the PPP-RTK users in the service area, reminding the users not to use the faulty real-time satellite clock and orbit correction product and the faulty signal bias product.

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