Real-time PPP-RTK signal deviation product integrity monitoring method

Abstract

The invention relates to a real-time PPP-RTK signal deviation product integrity monitoring method. The method comprises the following steps: S1) receiving real-time multi-frequency observation data of a monitoring station and generating a real-time satellite clock orbit correction product and a signal deviation product; s2) extracting equivalent space signal ranging residuals of corresponding frequency points based on ionosphere-free combination, and obtaining equivalent space signal ranging residuals corresponding to all frequency point combination modes; s3) establishing a residual hypothesis test model under a fault condition and a fault-free condition; s4) constructing a detection statistical magnitude and a detection threshold value of signal deviation product integrity monitoring, comparing the detection statistical magnitude with the detection threshold value to perform fault detection, if the detection result is no fault, entering a step S5, and if the detection result is fault, entering a step S6; s5) calculating the minimum detectable deviation, and executing availability judgment; and S6) according to a fault detection result and an availability judgment result, determining final alarm information of signal deviation products at different frequency points.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation technology, and in particular to a real-time PPP-RTK signal deviation product integrity monitoring method. Background Art

[0002] The Global Navigation Satellite System (GNSS) has powerful functions such as navigation, positioning, and timing. It is an important means to help realize the informatization and modernization of transportation. It covers multiple typical application scenarios such as sea, land, and air, and is widely used in transportation, military, agriculture and other fields, such as fully automatic landing of aircraft, fully automatic landing of carrier-based aircraft, vehicle-mounted navigation systems, unmanned driving, intelligent traffic control, intelligent marine operations, collaborative operations of smart agricultural machinery, etc.

[0003] Precision single-point real-time dynamic positioning technology (PPP-RTK) is a hot topic in the field of satellite navigation. Relying on the correction products such as satellite orbit, satellite clock error, signal deviation, code deviation, regional troposphere, and regional ionosphere provided by the cloud-based master station, the PPP-RTK user terminal can 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 less-manned application scenarios such as autonomous driving and precision agriculture. However, since intelligent and less-manned application scenarios often involve life safety-related applications, in addition to the requirements for positioning accuracy, the reliability of navigation positioning must also be guaranteed.

[0004] Signal deviation products are a prerequisite for PPP-RTK to complete ambiguity fixation and achieve high-precision fast convergence positioning. Signal deviation product failure will inevitably affect the reliability of PPP-RTK navigation and positioning. Signal deviation products are estimated based on global observation station network data and real-time satellite clock and orbit correction product modeling. Affected by factors such as observation station data failure, satellite clock and orbit correction product inaccuracy, and signal deviation product estimation model failure, the integrity of real-time satellite signal deviation products is difficult to guarantee, resulting in reduced reliability of PPP-RTK navigation and positioning, and restricting the implementation of PPP-RTK technology in intelligent and unmanned scenarios. Summary of the invention

[0005] In order to solve the above problems and ensure the integrity of PPP-RTK real-time signal deviation products, the present invention proposes a real-time PPP-RTK signal deviation product integrity monitoring method, which includes:

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

[0007] Step S2) extracting the equivalent spatial signal ranging residuals of the corresponding frequency points based on the ionosphere-free combination, traversing different frequency point combination modes, obtaining the equivalent spatial signal ranging residuals corresponding to all frequency point combination modes and classifying them, wherein the ranging residuals involving the signal deviation product using the same frequency point in all frequency point combinations are classified into one category;

[0008] Step S3) using the ranging residuals of all equivalent spatial signals corresponding to different frequency point combinations obtained in step S2, a residual hypothesis test model is established in the presence and absence of faults;

[0009] Step S4) constructs a detection statistic for integrity monitoring of real-time satellite signal deviation products, constructs a detection threshold based on the residual hypothesis test model under the fault-free condition established in step S3, and combines the continuity risk required by the real-time satellite clock and orbit correction products and the signal deviation products, and compares the detection statistic with the detection threshold to perform fault detection. If the detection result is no fault, proceed to step S5; if the detection result is a fault, proceed to step S6;

[0010] 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 product and the signal deviation product, calculate the minimum detectable deviation and perform availability judgment;

[0011] Step S6) According to the signal deviation product fault detection result performed in step S4 and the signal deviation product availability judgment result performed in step S5, the final alarm information of the signal deviation products at different frequencies is determined.

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

[0013] The present invention proposes a real-time PPP-RTK signal deviation product integrity monitoring method. The method 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, utilizes the frequency-related characteristics of the signal deviation product, and identifies the satellite clock and orbit correction product and the signal deviation product failure through multi-frequency point arrangement and combination and classification processing of the equivalent space signal ranging residual. The fault detection and availability judgment of the real-time signal deviation product are completed at the PPP-RTK cloud master station, and the final alarm information of the satellite clock and orbit correction product and the signal deviation product of each frequency point is determined, so as to ensure the integrity of the signal deviation product broadcasted by the PPP-RTK cloud master station. The method provides a solution for the implementation of the PPP-RTK technology in intelligent, unmanned and other application scenarios with high integrity requirements, which is of great significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention provides a flow chart of a real-time PPP-RTK signal deviation product integrity monitoring method. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] A real-time PPP-RTK signal deviation product integrity monitoring method provided by the present invention is completed at a PPP-RTK cloud master control station.

[0017] refer to Figure 1 The real-time PPP-RTK signal deviation product integrity monitoring method includes:

[0018] Step S1) The PPP-RTK cloud master station receives the real-time multi-frequency observation data from the monitoring station and uses the satellite data provided by the reference station to generate real-time satellite clock and orbit correction products and signal deviation products, which are used as input data for real-time PPP-RTK signal deviation product integrity monitoring. The real-time satellite clock and orbit correction products include real-time precision 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 signal deviation products, that is, the real-time multi-frequency observation data of the monitoring station cannot be used to generate real-time satellite clock and orbit correction products and signal deviation products. The PPP-RTK cloud master station uses the satellite data provided by the base station to generate real-time satellite clock and orbit correction products and signal deviation products.

[0020] The stations used in the real-time service process can be divided into reference stations and monitoring stations. In the present invention, the satellite data provided by the reference station is used to generate real-time satellite clock and orbit correction products and signal deviation products, and the data provided by the monitoring station is used for the integrity monitoring of the real-time PPP-RTK signal deviation product of the present invention. In the present invention, the observation data used cannot be used to generate satellite clock and orbit correction products and signal deviation products, and to verify the integrity of the signal deviation products, otherwise the integrity verification results 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 real-time satellite clock and orbit correction products and signal deviation products, but uses the satellite data provided by the reference station to generate real-time satellite clock and orbit correction products and signal deviation products.

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

[0022] Step S2) extracting the equivalent spatial signal ranging residuals of the corresponding frequency points based on the ionosphere-free combination, traversing different frequency point combination modes, obtaining the equivalent spatial signal ranging residuals corresponding to all frequency point combination modes and classifying them, wherein the ranging residuals involving the signal deviation product using the same frequency point in all frequency point combinations are classified into one category.

[0023] Using the observation data received from the monitoring station and the real-time satellite clock orbit correction products and signal deviation products generated using the satellite data provided by the reference station, the ranging residuals of the equivalent space signals corresponding to frequency points i and 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 points i and j, and the subscript IF represents the ionosphere-free combination. represents the ranging residual of the equivalent spatial 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 signal bias product of the real-time satellite, X IMS,m represents the location of monitoring station m, represents the satellite position corrected by the real-time precise satellite orbit product, c is the speed of light, Δt IMS,m is the receiver clock error of monitoring station m, is the satellite clock error corrected by the real-time satellite clock error product, Z w is the tropospheric wet delay, H(·) is the tropospheric wet delay mapping function, θ k is the satellite altitude 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 residual includes not only the signal bias product error but also the real-time satellite clock and orbit correction product error.

[0027] After extracting the equivalent spatial signal ranging residuals corresponding to frequency i and frequency j based on the ionosphere-free combination, modify the combination of frequency i and frequency j, and repeat the operation of equation (1), thereby traversing different frequency combinations and obtaining all equivalent spatial signal ranging residuals corresponding to all frequency combinations of the monitoring station. After completing the traversal of all frequency combinations and obtaining all corresponding equivalent spatial signal ranging residuals, classify all equivalent spatial signal ranging residuals, wherein the ranging residuals involving the signal deviation product using the same frequency in all frequency combinations are classified into one category:

[0028]

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

[0030] From equation (2), we can see that for satellite k, in the combination of frequency i and frequency j, as long as one of the frequency i or j is frequency a, the ranging residual of the equivalent spatial signal corresponding to the combination of frequency i and frequency j is divided into one category, that is, belonging to the set

[0031] Step S3) Using the ranging residuals of all equivalent spatial signals corresponding to different frequency point combinations obtained in step S2, a residual hypothesis testing model is established in the presence and absence of faults.

[0032] The equivalent spatial signal ranging residual obtained in step S2 It contains real-time satellite clock orbit correction products and signal deviation products. The detection statistics of real-time satellite signal deviation products can be constructed using equivalent spatial signal ranging residuals. The residual hypothesis test model under the conditions of fault and no fault is:

[0033]

[0034] Where H0 represents the no-fault mode hypothesis, H1 represents the fault mode hypothesis; μ is the ranging deviation existing in the fault mode; Represents the ranging residual of the equivalent spatial signal corresponding to the combination of frequency point i and frequency point j; is the standard deviation of the equivalent spatial signal ranging residual corresponding to the combination of frequency point i and frequency point j. This standard deviation can be expressed as the quality mark of the real-time satellite clock and orbit correction product. Signal Deviation Product Quality Mark And the measurement noise standard deviation The linear superposition is:

[0035]

[0036] The real-time satellite clock and orbit correction product quality indicator QI URA Product quality identification QI with signal deviation Bias,ij The measurement noise standard deviation σ is obtained through real-time broadcasting by the PPP-RTK cloud master station. δ,ijIt can be obtained by weighting the empirical altitude angle model.

[0037] Here is a brief explanation of the quality mark QI of the real-time satellite clock and orbit correction product. URA Product quality identification QI with signal deviation Bias,ij It is obtained by the existing known processing method before executing the real-time PPP-RTK signal deviation product integrity monitoring method, and the measurement noise standard deviation σ is obtained by weighting through the empirical elevation angle model. δ,ij The method adopts the existing known method, which will not be described here.

[0038] Step S4) Construct a detection statistic for integrity monitoring of the real-time satellite signal deviation product. According to the residual hypothesis test model under the fault-free condition established in step S3, and in combination with the continuity risk required by the real-time satellite clock and orbit correction product and the signal deviation product, construct a detection threshold. Compare the detection statistic with the detection threshold to perform fault detection. If the detection result is no fault, proceed to step S5. If the detection result is a fault, proceed to step S6.

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

[0040]

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

[0042] According to the residual hypothesis test model established based on equation (3), the detection statistic in the fault-free case obeys the central chi-square distribution with P degrees of freedom. Combined with the continuity risk required by the real-time satellite clock and orbit correction product and the signal deviation product, the detection threshold is calculated as:

[0043]

[0044] Where CR is the required continuity risk; N S is the number of available satellites; 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 .

[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 With detection threshold The size of the detection statistic is used to detect the fault. 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 point a are fault-free, and the process goes to step S5. If the test 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 satellite k is faulty and / or the signal deviation product corresponding to frequency point a is faulty, and the process goes to step S6. In the process of fault detection, the presence or absence of faults 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 faults 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 deviation product, the corresponding missed detection rate in the case of faults is calculated as:

[0049]

[0050] Where 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 orbit correction product and the signal deviation product, and the priori failure probability 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 point 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 by 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] Comparison of 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 the mark satellite k and the signal deviation product corresponding to the frequency point a are 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 deviation product error are coupled with each other, and the equivalent space signal ranging residual contains the signal deviation 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 deviation 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 the 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 are processed normally, that is, the alarm information is marked as normal, and the Boolean alarm flag bit bool aSet to "0" to indicate; otherwise, if the fault detection result is faulty 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 will be processed as an alarm, that is, the alarm information will be marked as a fault alarm, and the Boolean alarm flag bit bool a Set to "1" to indicate.

[0059] Based on the alarm information corresponding to all frequency points, the Boolean detection statistic ξ is constructed as follows:

[0060]

[0061] where ξ is a Boolean detection statistic, N f is the number of available frequencies, a represents the frequency, bool a Indicates the Boolean alarm flag of frequency point a.

[0062] The Boolean detection statistic ξ is related to the number of available frequency points N f A comparison is performed 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 is not equal to 0, it means 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 means 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 means that both the real-time satellite clock and orbit correction product and the signal deviation product are faulty, and the corresponding determination result is marked in the alarm information.

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

[0064] The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, some simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the scope of protection determined by the claims submitted for the present invention.

Claims

1. A real-time PPP-RTK signal deviation product integrity monitoring method, comprising: Step S1) The PPP-RTK cloud master station receives the real-time multi-frequency observation data from the monitoring station and uses the satellite data provided by the reference station to generate real-time satellite clock and orbit correction products and signal deviation products, which are used as input data for real-time PPP-RTK signal deviation product integrity monitoring; Step S2) extracting the equivalent spatial signal ranging residuals of the corresponding frequency points based on the ionosphere-free combination, traversing different frequency point combination modes, obtaining the equivalent spatial signal ranging residuals corresponding to all frequency point combination modes and classifying them, wherein the ranging residuals involving the signal deviation product using the same frequency point in all frequency point combinations are classified into one category; Step S3) using the ranging residuals of all equivalent spatial signals corresponding to different frequency point combinations obtained in step S2, a residual hypothesis test model is established in the presence and absence of faults; Step S4) constructs a detection statistic for integrity monitoring of real-time satellite signal deviation products, constructs a detection threshold based on the residual hypothesis test model under the fault-free condition established in step S3, and combines the continuity risk required by the real-time satellite clock and orbit correction products and the signal deviation products, and compares the detection statistic with the detection threshold to perform fault detection. If the detection result is no fault, proceed to step S5; if the detection result is a fault, proceed to step S6; 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 product and the signal deviation product, the minimum detectable deviation is calculated and the availability judgment is performed; 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.

2. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 1, wherein: The real-time satellite clock and orbit correction products include real-time precise satellite orbit products and real-time satellite clock error products. The real-time multi-frequency observation data received from the monitoring station does not participate in the generation of real-time satellite clock and orbit correction products and signal deviation products.

3. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 1, wherein: In step S2, the method for extracting the equivalent spatial signal ranging residual of the corresponding frequency point based on the ionosphere-free combination is: The superscript k represents the satellite, the subscript m represents the monitoring station, the subscript ij represents the combination of frequency points i and j, and the subscript IF represents the ionosphere-free combination. represents the ranging residual of the equivalent spatial 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 signal bias product of the real-time satellite, X IMS,m represents the location of monitoring station m, represents the satellite position corrected by the real-time precise satellite orbit product, c is the speed of light, Δt IMS,m is the receiver clock error of monitoring station m, is the satellite clock error corrected by the real-time satellite clock error product, Z w is the tropospheric wet delay, H(·) is the tropospheric wet delay mapping function, θ k is the satellite altitude angle, is the ambiguity corresponding to the ionosphere-free combination.

4. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 1, wherein: In step S2, the method of classifying the ranging residuals involving the signal deviation product using the same frequency point in all frequency point combinations into one category is: in is the set of ranging residuals corresponding to the signal bias products of satellite k and frequency point a, Represents the ranging residual of the equivalent spatial signal at frequency point a, represents the ranging residual of the equivalent space signal corresponding to the combination of frequency point i and frequency point j; k represents the satellite, a represents the frequency point, m represents the monitoring station, and M is the set of all monitoring stations.

5. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 1, wherein: In step S3, the residual hypothesis test model established in the case of fault and no fault is: Where H0 represents the no-fault mode hypothesis, H1 represents the fault mode hypothesis; μ is the ranging deviation existing in the fault mode; Represents the ranging residual of the equivalent spatial signal corresponding to the combination of frequency point i and frequency point j; is the standard deviation of the equivalent spatial signal ranging residual corresponding to the combination of frequency point i and frequency point j. This standard deviation can be expressed as the quality mark of the real-time satellite clock and orbit correction product. Signal Deviation Product Quality Mark And the measurement noise standard deviation The linear superposition is: The real-time satellite clock and orbit correction product quality indicator QI URA Product quality identification QI with the signal deviation Bias,ij The measurement noise standard deviation σ is obtained through real-time broadcasting by the PPP-RTK cloud master station. δ,ij Obtained by weighting the empirical altitude angle model.

6. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 1, wherein: In step S4, the method for constructing the detection statistics for real-time satellite signal deviation product integrity monitoring is as follows: in represents the detection statistic of the real-time satellite signal deviation product for satellite k and frequency point a, is the set of ranging residuals corresponding to the signal bias products of satellite k and frequency point a, Represents the ranging residual of the equivalent spatial signal at frequency point a, Indicates the standard deviation of the equivalent spatial signal ranging residual of frequency point a; The method to construct 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 point a, Represents the probability density function of the chi-square distribution, where x is the independent variable and P is the degrees of freedom.

7. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 6, wherein: In step S4, the specific method of comparing the detection statistic with the detection threshold to perform fault detection is: Compare the detection statistic with the detection threshold. 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 satellite k and the signal deviation product corresponding to frequency point a are faulty; 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 satellite k is faulty and / or the signal deviation product corresponding to frequency point a is faulty.

8. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 6, wherein: In step S5, the method for obtaining the minimum detectable deviation is: in represents the minimum detectable deviation corresponding to satellite k and frequency point a, is the non-centralized parameter corresponding to satellite k and frequency point a; Get the non-centralized parameters The method is: Where P MD is the missed detection rate, 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 deviation product, is the detection threshold for satellite k and frequency point a, represents the probability density function of the chi-square distribution, where x is the independent variable, P is the degree of freedom, is the non-centralized parameter corresponding to satellite k and frequency point a; The method for performing availability judgment is: Compare the minimum detectable deviation with the preset fault detection sensitivity alarm limit. If the minimum detectable deviation is less than the fault detection sensitivity alarm limit, 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 is greater than or equal to the fault detection sensitivity alarm limit, the monitoring results of the real-time satellite clock and orbit correction product corresponding to the marked satellite k and the signal deviation product corresponding to the frequency point a are unavailable.

9. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 1, wherein: In step S6, it also includes: determining the final alarm information of the real-time satellite clock orbit correction product, and the execution method of step S6 is: counting the number of faulty results and unavailable results in the fault detection results and the availability judgment results, and determining the final alarm information of the real-time satellite clock orbit correction product and the signal deviation products of different frequency points based on the statistical number, specifically including: If the fault detection result is no fault and the availability judgment result is available, the Boolean alarm flag bit bool a If the fault detection result is faulty and / or the availability judgment result is unavailable, the Boolean alarm flag bit bool a Set to "1" to represent; construct the Boolean detection statistic ξ as follows: where ξ is a Boolean detection statistic, N f is the number of available frequencies, a represents the frequency, bool a Indicates the Boolean alarm flag of frequency point a; The Boolean detection statistic is compared with the number of available frequency points 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 is less than the number of available frequency points and is not equal to 0, it means 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 is equal to the number of available frequency points, it means 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 is equal to 0, it means that both the real-time satellite clock and orbit correction product and the signal deviation product are not faulty; the corresponding determination result is marked in the alarm information.

10. The real-time PPP-RTK signal deviation product integrity monitoring method according to claim 9 further comprises: The final warning information will be broadcast to PPP-RTK users in the service area to remind them not to use faulty real-time satellite clock and orbit correction products and faulty signal deviation products.

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