Method and apparatus for estimating global navigation satellite system satellite inter-frequency clock bias

Abstract

The embodiment of the application provides a global navigation satellite system satellite frequency interval clock bias estimation method and device, the method comprises: calculating the observation data of each satellite collected by a plurality of observation stations in a specified time period to generate a harmonic function coefficient table; if the arc length of the current data arc segment is greater than or equal to the set length threshold, the corresponding first coefficient group is matched according to the harmonic function coefficient table, and the first coefficient group is determined as the initial value of the fitting coefficient group; the least square fitting is carried out on the current data arc segment through the initial value of the fitting coefficient group, and the satellite frequency interval clock bias fitting value of the current data arc segment is obtained, so as to eliminate the error of positioning calculation; the arc length to be processed is not required, the data amount is reduced, and the timeliness of fitting processing is improved.

Description

Technical Field

[0001] This invention relates to the field of satellite technology, and in particular to a method and apparatus for estimating inter-frequency clock offsets of satellites in a global navigation satellite system. Background Technology

[0002] The Global Navigation Satellite System (GNSS) suffers from phase inconsistencies between carrier waves of multiple frequencies, a phenomenon known as inter-frequency clock bias (IFCB). To eliminate IFCB and reduce the computational load on real-time GNSS services, IFCB estimation is necessary.

[0003] In related technologies, the method for processing IFCB is based on the differenced ionosphere-free linear combination (DIF) value of a single station and a single satellite with three frequencies over three arc days. A sliding window fitting of the IFCB is performed using a set of harmonic functions under the least squares criterion. When there are many observation stations and satellites, the amount of data that needs to be processed by the above method becomes enormous, resulting in an excessive computational load. Furthermore, if data interruption or loss occurs, the fitting coefficients will show a significant deviation, and the fitting results will become invalid. Summary of the Invention

[0004] One object of this invention is to provide a method for estimating the inter-frequency clock offset of a Global Navigation Satellite System (GNSS), which reduces the amount of data processing and improves the timeliness and accuracy of fitting results. Another object of this invention is to provide a device for estimating the inter-frequency clock offset of a GNSS. A further object of this invention is to provide a computer-readable medium. A still other object of this invention is to provide a computer device.

[0005] To achieve the above objectives, this invention discloses a method for estimating inter-frequency clock offsets of satellites in a global navigation satellite system, comprising:

[0006] The observation data of each satellite collected from multiple observation stations for a specified time period are calculated to generate a table of harmonic function coefficients;

[0007] If the arc length of the current data arc segment is greater than or equal to the set length threshold, the corresponding first coefficient group is matched according to the harmonic function coefficient table, and the first coefficient group is determined as the initial value of the fitting coefficient group.

[0008] By performing least-squares fitting on the current data arc using the initial values ​​of the fitting coefficient set, the satellite inter-frequency clock offset fitting value for the current data arc is obtained, thereby eliminating positioning calculation errors.

[0009] Preferably, before matching the corresponding first coefficient group according to the harmonic function coefficient table if the arc length of the current data arc segment is greater than or equal to the set length threshold, the method further includes:

[0010] Based on the visual status of the received satellite signals, the initial data arc is divided into multiple continuous data arcs;

[0011] Each continuous data arc segment is subjected to cycle slip detection and repair processing to obtain multiple repaired data arc segments.

[0012] Preferably, the method further includes:

[0013] If the length of the current data arc segment is less than the set length threshold, the pre-set second coefficient group will be determined as the initial value of the fitting coefficient group.

[0014] Preferably, the observation data of each satellite collected from multiple observation stations for a specified time period are calculated to generate a harmonic function coefficient table, including:

[0015] Based on observation data collected from multiple observation stations for a specified time period for each satellite, multiple three-frequency deionization geometric combination values ​​for each satellite are calculated.

[0016] By using the least squares criterion, the coefficient set corresponding to each satellite is calculated based on the multiple three-frequency deionization geometric combination values ​​of each satellite;

[0017] A harmonic function coefficient table is generated based on the coefficient groups corresponding to multiple satellites.

[0018] Preferably, using the least squares criterion, based on multiple three-frequency deionization geometric combination values ​​for each satellite, the coefficient set corresponding to each satellite is calculated, including:

[0019] By using the least squares criterion, multiple geometrically unmatched three-frequency deionization values ​​for each satellite are fitted to obtain multiple sets of initial coefficients for each satellite.

[0020] The average value of multiple initial coefficients corresponding to each satellite is taken to obtain the coefficient set corresponding to each satellite.

[0021] Preferably, after performing least-squares fitting on the current data arc segment using the initial values ​​of the fitting coefficient set to obtain the satellite inter-frequency clock offset fitting value for the current data arc segment, the method further includes:

[0022] Obtain the next data arc segment and designate it as the current data arc segment;

[0023] Determine whether the length of the current data arc segment is greater than or equal to the set length threshold;

[0024] If so, continue to execute the steps of matching the corresponding first coefficient group according to the harmonic function coefficient table and determining the first coefficient group as the initial value of the fitting coefficient group, until all data arcs are fitted.

[0025] If not, continue with the step of determining the pre-set second coefficient group as the initial value of the fitting coefficient group until all data segments are fitted.

[0026] This invention also discloses a device for estimating inter-frequency clock offsets of global navigation satellite systems, comprising:

[0027] The generation unit is used to calculate the observation data of each satellite collected by multiple observation stations for a specified time period and generate a harmonic function coefficient table.

[0028] The matching unit is used to match the corresponding first coefficient group according to the harmonic function coefficient table if the arc length of the current data arc segment is greater than or equal to the set length threshold, and to determine the first coefficient group as the initial value of the fitting coefficient group.

[0029] The fitting unit is used to perform least-squares fitting on the current data arc segment using the initial values ​​of the fitting coefficient set, so as to obtain the satellite inter-frequency clock deviation fitting value of the current data arc segment and eliminate the positioning solution error.

[0030] Preferably, the device further includes:

[0031] The segmentation unit is used to divide the received initial data arc into multiple continuous data arcs according to the visibility of the received satellite signal;

[0032] The processing unit is used to perform cycle slip detection and repair processing on each continuous data arc segment to obtain multiple repaired data arc segments.

[0033] Preferably, the device further includes:

[0034] The determination unit is used to determine the pre-set second coefficient group as the initial value of the fitting coefficient group if the arc length of the current data arc segment is less than the set length threshold.

[0035] Preferably, the generation unit is specifically used to calculate multiple three-frequency ionospheric de-geometric combination values ​​for each satellite based on the observation data of each satellite collected by multiple observation stations for a specified time period; calculate the coefficient group corresponding to each satellite based on the multiple three-frequency ionospheric de-geometric combination values ​​for each satellite using the least squares criterion; and generate a harmonic function coefficient table based on the coefficient groups corresponding to multiple satellites.

[0036] Preferably, the generation unit is specifically used to fit multiple three-frequency deionization geometric combination values ​​of each satellite using the least squares criterion to obtain multiple sets of initial coefficients corresponding to each satellite; and to take the average value of the multiple sets of initial coefficients corresponding to each satellite to obtain the coefficient set corresponding to each satellite.

[0037] Preferably, the device further includes:

[0038] The acquisition unit is used to acquire the next data arc segment and determine the next data arc segment as the current data arc segment;

[0039] The judgment unit is used to determine whether the arc length of the current data arc is greater than or equal to the set length threshold. If so, the matching unit is triggered to continue executing the step of matching the corresponding first coefficient group according to the harmonic function coefficient table and determining the first coefficient group as the initial value of the fitting coefficient group, until all data arcs are fitted. If not, the determination unit is triggered to continue executing the step of determining the pre-set second coefficient group as the initial value of the fitting coefficient group, until all data arcs are fitted.

[0040] The present invention also discloses a computer-readable medium having a computer program stored thereon, which, when executed by a processor, implements the method described above.

[0041] The present invention also discloses a computer device, including a memory and a processor, wherein the memory is used to store information including program instructions, and the processor is used to control the execution of the program instructions, wherein the processor executes the program to implement the method described above.

[0042] The present invention also discloses a computer program product, including a computer program / instructions that, when executed by a processor, implement the method described above.

[0043] This invention calculates the harmonic function coefficient table by collecting observation data from multiple observation stations for each satellite over a specified time period. If the arc length of the current data segment is greater than or equal to a set length threshold, the corresponding first coefficient group is matched according to the harmonic function coefficient table, and the first coefficient group is determined as the initial value of the fitting coefficient group. The current data segment is then fitted with least squares using the initial value of the fitting coefficient group to obtain the satellite inter-frequency clock deviation fitting value for the current data segment, thereby eliminating positioning calculation errors, reducing data processing volume, and improving fitting timeliness and accuracy of fitting results. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A time trend chart of DIF data for each satellite is provided as an embodiment of the present invention;

[0046] Figure 2 A time trend chart of DIF and IFCB of three GPS Block IIF satellites provided in an embodiment of the present invention;

[0047] Figure 3 A time-domain trend diagram of the IFCB of each satellite;

[0048] Figure 4 A flowchart illustrating a method for estimating inter-frequency clock bias in a global navigation satellite system, provided as an embodiment of the present invention;

[0049] Figure 5 A flowchart illustrating another method for estimating inter-frequency clock bias in a global navigation satellite system, provided in an embodiment of the present invention;

[0050] Figure 6 A fitting graph of data arc segments with arc lengths less than a length threshold is provided as an embodiment of the present invention;

[0051] Figure 7 This invention provides a DIF trend chart of the same satellite observed from different stations, as provided in an embodiment of the invention.

[0052] Figure 8 A short arc segment IFCB fitting trend graph with a given initial value is provided for an embodiment of the present invention;

[0053] Figure 9 This is a schematic diagram of the structure of a satellite inter-frequency clock bias estimation device for a global navigation satellite system provided in an embodiment of the present invention;

[0054] Figure 10 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] To facilitate understanding of the technical solution provided in this application, the relevant content of the technical solution will be explained below. With the development and deepening of high-precision applications of Global Navigation Satellite System (GNSS), the importance of GNSS carrier phase observations is increasingly highlighted. Currently, to provide better redundancy and faster ambiguity fixing, the observation signals of various GNSS systems have gradually evolved from single-frequency and dual-frequency to multi-frequency systems. Due to the inconsistency between the carrier phases of multi-frequency GNSS signals, inter-frequency clock bias (IFCB) is generated. The existence of IFCB means that the satellite clock bias estimate obtained using an ionospheric de-spheric combination of two frequencies cannot be used for other frequency combinations, thus affecting the performance of precise point positioning.

[0057] By using the carrier phase observation equation, the observed data is calculated to obtain the carrier observation value at the current frequency. When three frequencies of carrier observation are available, two sets of dual-frequency ionosphere-free linear combination (IF) values ​​can be obtained. Subtracting the two sets of IF values ​​yields the three-frequency ionosphere-free linear combination (DIF) value. Taking the three-frequency carrier phase observation data of various Galileo system satellites at the ARHT observation station as an example... Figure 1 A time trend chart of DIF data for each satellite is provided as an embodiment of the present invention, such as... Figure 1 As shown, the horizontal axis of this trend graph represents the epoch, with a sampling rate of 1 / 30 Hz, and the vertical axis represents DIF (difference in frequency), with units in meters (m). Different grayscale colors represent different satellites. It can be seen that the DIF of this system conforms to white noise characteristics; therefore, the IFCB (inter-frequency phase cross-section) between its three frequency signals can be considered negligible. Taking the three-frequency carrier phase observation data of three GPS Block IIF satellites from the acquisition observation station (ARHT station) as an example... Figure 2 A time trend chart of DIF and IFCB of three GPS Block IIF satellites provided in an embodiment of the present invention, as shown below. Figure 2As shown, the horizontal axis of this trend chart represents the epoch, with a sampling rate of 1 / 30 Hz, and the vertical axis represents the DIF or IFCB estimate, both in meters (m). The three GPS Block IIF satellites are G09, G24, and G27. Figure 2 As shown in the legend, different shades of gray represent different values ​​for different satellites. From Figure 2 As can be seen, although both are ARHT stations, the three-frequency DIF signals received from the three GPS Block IIF satellites are different compared to... Figure 1 The DIFCB of each satellite in China has a significant impact, and from Figure 2 The data shows that the variation trend of IFCB for each satellite is different, but they all have periodic repetition, with peak values ​​reaching close to 0.2m.

[0058] To better understand the characteristics of the IFCB, 15 stations in the International GNSS Service (IGS) tracking network that can receive tri-frequency Global Positioning System (GPS) signals were selected. The basic information of the stations is shown in Table 1.

[0059] Table 1. Basic information of the selected IGS stations

[0060]

[0061] The basic information of the stations includes the station names of multiple stations, the location of each station, and the receiver type, which is JAVAD TRE_3DELTA 4.1.01.

[0062] Fourier transform (FFT) analysis was performed on the combined DIF values ​​of multiple stations over 30 consecutive days to obtain the time-domain variation trend of IFCB for each satellite. Taking G09, G24, G27, and G30 satellites as examples... Figure 3 The following is a time-domain trend diagram of the IFCB of each satellite, such as... Figure 3 As shown, the horizontal axis of the trend chart for each satellite represents the sampling frequency, and the vertical axis represents the IFCB (In-Frequency Control Block). Different grayscale colors represent different stations. From Figure 3 It can be seen that although the IFCB of each satellite has different trends in the time domain, it exhibits similar characteristics in the frequency domain. That is, the IFCB of each satellite has multiple frequency components, with the largest amplitude periods being 4.7h, 6h, 8h, 12h and 24h, respectively.

[0063] The following uses a Global Navigation Satellite System (GNSS) inter-frequency clock bias estimation device as an example to illustrate the implementation process of the GNSS inter-frequency clock bias estimation method provided in this embodiment of the invention. It is understood that the execution entities of the GNSS inter-frequency clock bias estimation method provided in this embodiment of the invention include, but are not limited to, a GNSS inter-frequency clock bias estimation device.

[0064] Figure 4 A flowchart of a method for estimating inter-frequency clock offsets of a global navigation satellite system provided in an embodiment of the present invention is shown below. Figure 4 As shown, the method includes:

[0065] Step 101: Calculate the observation data of each satellite for a specified time period collected by multiple observation stations to generate a harmonic function coefficient table.

[0066] In this embodiment of the invention, the specified time period can be set according to actual needs, and the specified time period is greater than or equal to 3 days.

[0067] Step 102: If the arc length of the current data arc segment is greater than or equal to the set length threshold, match the corresponding first coefficient group according to the harmonic function coefficient table, and determine the first coefficient group as the initial value of the fitting coefficient group.

[0068] Step 103: Perform least squares fitting on the current data arc segment using the initial values ​​of the fitting coefficient set to obtain the satellite inter-frequency clock deviation fitting value for the current data arc segment, thereby eliminating the positioning calculation error.

[0069] In the technical solution provided by this invention, observation data of each satellite collected by multiple observation stations for a specified time period are calculated to generate a harmonic function coefficient table. If the arc length of the current data arc is greater than or equal to a set length threshold, the corresponding first coefficient group is matched according to the harmonic function coefficient table, and the first coefficient group is determined as the initial value of the fitting coefficient group. The current data arc is fitted with least squares using the initial value of the fitting coefficient group to obtain the satellite inter-frequency clock deviation fitting value of the current data arc, so as to eliminate the positioning calculation error, reduce the amount of data processing, and improve the fitting timeliness and the accuracy of the fitting results.

[0070] Figure 5 A flowchart of another method for estimating inter-frequency clock bias of a global navigation satellite system provided in an embodiment of the present invention is shown below. Figure 5 As shown, the method includes:

[0071] Step 201: According to the visual state of the received satellite signal, divide the received initial data arc into multiple continuous data arcs.

[0072] In this embodiment of the invention, each step is performed by the global navigation satellite system inter-frequency clock offset estimation device.

[0073] In this embodiment of the invention, due to the operation of the satellite, the visible state of the satellite signal received from the ground includes breakpoints, and the received initial data arc is discontinuous; according to the visible state, the initial arc is divided from the breakpoint into multiple continuous data arcs.

[0074] Step 202: Perform cycle slip detection and repair processing on each continuous data arc segment to obtain multiple repaired data arc segments.

[0075] In this embodiment of the invention, cycle slip detection and repair processing are performed on continuous data arc segments to eliminate the step effect caused by cycle slips and obtain repaired data arc segments.

[0076] It is worth noting that the specific methods for cycle slip detection and repair can be selected according to actual needs, and the embodiments of the present invention do not limit the selection of specific methods for cycle slip detection and repair.

[0077] Step 203: Determine the arc length of the current data arc segment and the set length threshold to determine the initial value of the fitting coefficient group, and determine the initial value of the fitting coefficient group through the determination method.

[0078] In this embodiment of the invention, the arc length is the continuous observation duration of the current data arc segment. The determination method includes determining the initial value of the fitting coefficient set based on a harmonic function coefficient table or based on a set linear function.

[0079] In this embodiment of the invention, step 203 specifically includes:

[0080] Step 2031: Based on the observation data of each satellite collected by multiple observation stations for a specified time period, calculate multiple three-frequency ionosphere-free linear combination values ​​(DIF) for each satellite.

[0081] In this embodiment of the invention, the specified time period can be set according to actual needs, and the specified time period is greater than or equal to 3 days.

[0082] In this embodiment of the invention, the carrier phase observation data is calculated using the carrier phase observation equation to obtain the carrier observation data at the current frequency. The observation data consists of relevant data from continuous observation data arcs, including but not limited to the geometric distance from the satellite to the station, satellite clock error, receiver clock error, carrier wavelength, carrier phase integer ambiguity, ionospheric delay along the signal propagation path, tropospheric delay along the signal propagation path, multipath error, carrier phase observation noise, and the sum of error sources.

[0083] Specifically, through The carrier observations at the current frequency i are calculated from the observed data. Let ρ be the carrier observation at frequency i, ρ be the geometric distance from the satellite to the station, i be the frequency marker, c be the speed of light, and dt be the carrier observation. s For satellite clock bias, dt r Let λ be the receiver clock bias, λ be the carrier wavelength, N be the carrier phase integer ambiguity, I be the ionospheric delay along the signal propagation path, T be the tropospheric delay along the signal propagation path, M be the multipath error, ε be the carrier phase observation noise, and δ be the sum of error sources. The sum of error sources includes the sum of other error sources in the carrier phase observation, specifically including but not limited to hardware delay deviations at the satellite and receiver ends, antenna phase winding corrections, and higher-order terms of ionospheric delay.

[0084] In this embodiment of the invention, the carrier observations of three frequencies are calculated to obtain two sets of dual-frequency ionosphere-free linear combination (IF) values. The difference between the two sets of IF values ​​is then obtained to obtain the DIF.

[0085] Specifically, the DIF of the satellite is obtained by calculating the carrier observations at three frequencies using the following formula.

[0086]

[0087] in, For the first carrier observation at the first frequency, For the second carrier observation at the second frequency, For the third carrier observation at the third frequency, For the first carrier observation and the second carrier observation, Let f1 be the first carrier observation and f2 be the second carrier observation, f3 be the third carrier observation, M1 be the first multipath error, M2 be the second multipath error, M3 be the third multipath error, ε1 be the first carrier phase observation noise, ε2 be the second carrier phase observation noise, ε3 be the third carrier phase observation noise, δ1 be the sum of the first error sources, δ2 be the sum of the second error sources, and δ3 be the sum of the third error sources.

[0088] Under normal circumstances, errors such as hardware delay deviation, antenna phase winding correction, and higher-order terms of ionospheric delay are relatively small and can be ignored. Therefore, DIF can be regarded as a weighted combination of observation noise and multipath error, and should have characteristics similar to white noise.

[0089] Step 2032: Using the least squares criterion, calculate the coefficient set corresponding to each satellite based on the multiple DIFs of each satellite.

[0090] In this embodiment of the invention, multiple DIFs of each satellite are fitted using the least squares criterion to obtain multiple sets of initial coefficients corresponding to each satellite; the average value of the multiple sets of initial coefficients corresponding to each satellite is taken to obtain the coefficient set corresponding to each satellite.

[0091] Specifically, by using a set of harmonic functions to perform a sliding window fitting of the IFCB under the least squares criterion, the expression of this set of harmonic functions is as follows:

[0092]

[0093] Where n is the number of harmonic functions, a1, a2, b i1 and b i2 (i = 1, ..., n) represents the harmonic function coefficients to be estimated, i.e., the coefficient set. Depending on the required fitting accuracy, n can be any natural number, and T... i This corresponds to the period of the harmonic function. As an alternative, when n = 5, the period of the harmonic function is T. i The approximation effect is better when the time is 4.7h, 6h, 8h, 12h and 24h.

[0094] For each satellite, a fitting calculation is performed to obtain multiple sets of initial coefficients for each satellite; the average value of the multiple sets of initial coefficients is taken to obtain the coefficient set for each satellite, and the coefficient set for each satellite is recorded and stored.

[0095] Step 2033: Generate a harmonic function coefficient table based on the coefficient groups corresponding to multiple satellites.

[0096] In this embodiment of the invention, the coefficient group corresponding to each satellite is recorded and stored, and the coefficient groups corresponding to multiple satellites are combined to form a harmonic function coefficient table. The harmonic function coefficient table includes multiple satellites and the coefficient group corresponding to each satellite.

[0097] Step 2034: Determine whether the arc length of the current data arc segment is greater than or equal to the set length threshold. If yes, proceed to step 2035; otherwise, proceed to step 2036.

[0098] In this embodiment of the invention, if the arc length of the current data arc segment is greater than or equal to the set length threshold, it indicates that the observation time is relatively long. The initial value of the fitting coefficient group is determined according to the harmonic function coefficient table, and step 2035 is continued. If the arc length of the current data arc segment is less than the set length threshold, it indicates that the observation time is relatively short. The initial value of the fitting coefficient group is determined according to the set linear function, and step 2036 is continued.

[0099] In this embodiment of the invention, the length threshold can be set according to actual conditions, and this embodiment of the invention does not limit it. As an optional solution, the length threshold is 20 minutes.

[0100] Step 2035: Match the corresponding first coefficient group according to the pre-calculated harmonic function coefficient table, and determine the first coefficient group as the initial value of the fitting coefficient group, and continue to execute step 204.

[0101] In this embodiment of the invention, the harmonic function coefficient table includes multiple satellites and a coefficient group corresponding to each satellite. The satellite to which the current data arc belongs is matched with the satellites in the harmonic function coefficient table to obtain the corresponding first coefficient group; the first coefficient group is determined as the initial value of the fitting coefficient group, and step 204 is continued.

[0102] Step 2036: Determine the pre-set second coefficient group as the initial value of the fitting coefficient group.

[0103] In this embodiment of the invention, the second coefficient group is preset, and the coefficient group includes a1, a2, b i1 and b i2 (i = 1, ..., n), set the value of a2 in the second coefficient group to 1, and set the values ​​of other coefficients to 0, that is: the second coefficient group is 0, 1, 0...0. If the arc length of the current data segment is less than the set length threshold, the second coefficient group is determined as the initial value of the fitting coefficient group.

[0104] In this embodiment of the invention, the fitting coefficient group for data arc segments whose arc length is less than the length threshold is specified because, due to limitations of the observation cutoff angle or hardware failures such as receiver lockout, there may be a short segment of observation data whose DIF fluctuations are insufficient to reflect the trend of IFCB. Therefore, when the initial fitting values ​​of other observation arc segments of the same satellite are used, a large fitting deviation will occur.

[0105] Figure 6 A fitting graph of data arc segments with arc lengths less than a length threshold is provided as an embodiment of the present invention, such as... Figure 6 As shown, the horizontal axis represents epochs with a sampling rate of 1 / 30 Hz, and the vertical axis represents DIF or IFCB in meters (m). When a certain observation arc segment is less than 50 epochs, the DIF is relatively flat, approaching linear characteristics. When using the initial fitting values ​​from other observation arc segments of the same satellite, a large fitting deviation occurs. If the second set of coefficients is used as the fitting coefficient set, a smaller fitting deviation can be obtained, improving the fitting effect.

[0106] Step 204: Perform least-squares fitting on the current data arc segment using the initial values ​​of the fitting coefficient set to obtain the satellite IFCB fitting value of the current data arc segment, thereby eliminating the positioning solution error.

[0107] Specifically, through The satellite IFCB fitting value for the current data arc segment is obtained by performing a least-squares fit on the fitting coefficient set. Here, ν represents the satellite IFCB fitting value, n is the number of harmonic functions, and a1, a2, b... i1 and b i2 (i = 1, ..., n) is the set of fitting coefficients.

[0108] Step 205: Obtain the next data arc segment and designate it as the current data arc segment. Continue executing step 203 until all data arc segments are fitted.

[0109] Specifically, after the satellite IFCB fitting value for the current data arc segment is calculated, it is determined whether there is another data arc segment. If so, the next data arc segment is determined as the current data arc segment, and step 203 is continued; if not, it indicates that all data arc segments have been fitted and the process ends.

[0110] Furthermore, satellite IFCB is a systematic error. Once the data arc fitting is complete, the calculated satellite IFCB fitting value can be eliminated during subsequent positioning calculations, thereby improving the positioning accuracy.

[0111] The following section uses satellite G03 observation data as an example to describe in detail the method for estimating the inter-frequency clock offset of global navigation satellite systems:

[0112] Fifteen stations were selected from Table 1, and observation data for three days were collected from these stations. The observation data were then used to calculate the DIF of satellite G03. Figure 7 This invention provides an embodiment of a DIF trend chart of the same satellite observed from different stations, such as... Figure 7 As shown, the horizontal axis represents the epoch, with a sampling rate of 1 / 30 Hz, and the vertical axis represents DIF, with units in meters (m). Different grayscale colors represent different stations. From Figure 7It can be seen that, since the IFCB is related to the satellite hardware, the three-frequency IFCBs of the same satellite exhibit similar characteristics, and the harmonic function coefficients obtained during fitting are also similar. If the harmonic function coefficients corresponding to different satellites are recorded and used directly as the initial values ​​for fitting in subsequent processing, it is not necessary to solve the problem jointly for observation arcs over multiple days, and the convergence speed of the fitting process is also accelerated. After cycle slip detection and repair for each continuous data arc, the DIF of each station is fitted using the least squares criterion to obtain 15 sets of initial coefficients corresponding to satellite G03; the average value of the 15 sets of initial system coefficients is taken, and the resulting coefficient sets are shown in Table 2.

[0113] Table 2. Coefficient Groups for G03 Satellite

[0114] <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[b 11 ]]> <![CDATA[b 12 ]]> <![CDATA[b 21 ]]> <![CDATA[b 22 ]]> 1.0099 -0.86792 0.64142 0.15131 -1.2229 1.1902 <![CDATA[b 31 ]]> <![CDATA[b 32 ]]> <![CDATA[b 41 ]]> <![CDATA[b 42 ]]> <![CDATA[b 51 ]]> <![CDATA[b 52 ]]> -0.38260 0.045876 -0.29071 0.0088886 -0.068357 0.014919

[0115] Using the coefficient set shown in Table 2, least squares fitting is performed on the current data arc segment to obtain the satellite IFCB fitting value for the current data arc segment. Figure 8 An example of a short arc segment IFCB fitting trend plot provided by an embodiment of the present invention, such as... Figure 8 As shown, the horizontal axis represents the epoch, with a sampling rate of 1 / 30 Hz, and the vertical axis represents the DIF or IFCB estimate, in meters (m). Figure 8 It can be seen that even when the data arc is only about 5 hours long, an ideal fitting effect can be achieved, indicating that the obtained coefficient set is effective. Furthermore, comparing the above strategy with the method of using all-zero coefficients as the fitting coefficient set (without given initial values), and statistically analyzing the computation time, it was found that under the same constraints, processing one day's data from a single station and single satellite (sampling rate 1 / 30Hz), the former averaged 6.7320 seconds, while the latter averaged 12.029 seconds. Therefore, selecting the coefficient set from Table 2 as the fitting coefficient set can improve the timeliness of the fitting process.

[0116] In this embodiment of the invention, no requirement is set for the length of the observed data arc segment. Initial values ​​of the corresponding fitting coefficient group are set for observed data arc segments of different lengths, which reduces the amount of data processing and can accelerate the convergence speed of the least squares estimation of IFCB. When dealing with massive amounts of data, it can greatly save processing time and improve the fitting timeliness.

[0117] In the technical solution of the satellite inter-frequency clock bias estimation method for a global navigation satellite system provided in this invention, the observation data of each satellite collected by multiple observation stations for a specified time period are calculated to generate a harmonic function coefficient table. If the arc length of the current data arc is greater than or equal to a set length threshold, the corresponding first coefficient group is matched according to the harmonic function coefficient table, and the first coefficient group is determined as the initial value of the fitting coefficient group. The current data arc is fitted with least squares using the initial value of the fitting coefficient group to obtain the satellite inter-frequency clock bias fitting value of the current data arc, thereby eliminating positioning calculation errors, reducing data processing volume, and improving fitting timeliness and accuracy of fitting results.

[0118] Figure 9 This is a schematic diagram of a global navigation satellite system (GNSS) inter-frequency clock bias estimation device provided in an embodiment of the present invention. This device is used to execute the aforementioned GNSS inter-frequency clock bias estimation method, such as... Figure 9 As shown, the device includes: a generation unit 11, a matching unit 12, and a fitting unit 13.

[0119] The generation unit 11 is used to calculate the observation data of each satellite collected by multiple observation stations for a specified time period and generate a harmonic function coefficient table;

[0120] The matching unit 12 is used to match the corresponding first coefficient group according to the harmonic function coefficient table if the arc length of the current data arc segment is greater than or equal to the set length threshold, and to determine the first coefficient group as the initial value of the fitting coefficient group.

[0121] The fitting unit 13 is used to perform least-squares fitting on the current data arc segment through the fitting coefficient set to obtain the satellite inter-frequency clock deviation fitting value of the current data arc segment, so as to eliminate the positioning solution error.

[0122] In this embodiment of the invention, the device further includes a division unit 14 and a processing unit 15.

[0123] The segmentation unit 14 is used to divide the received initial data arc into multiple continuous data arcs according to the visibility of the received satellite signal.

[0124] The processing unit 15 is used to perform cycle slip detection and repair processing on each continuous data arc segment to obtain multiple repaired data arc segments.

[0125] In this embodiment of the invention, the device further includes a determining unit 16.

[0126] The determining unit 16 is used to determine the pre-set second coefficient group as the fitting coefficient group if the arc length of the current data arc segment is less than the set length threshold.

[0127] In this embodiment of the invention, the generation unit 11 is specifically used to calculate multiple three-frequency de-ionization geometric combination values ​​for each satellite based on the observation data of each satellite collected by multiple observation stations for a specified time period; calculate the coefficient group corresponding to each satellite based on the multiple three-frequency de-ionization geometric combination values ​​for each satellite using the least squares criterion; and generate a harmonic function coefficient table based on the coefficient groups corresponding to multiple satellites.

[0128] In this embodiment of the invention, the generation unit 11 is specifically used to fit multiple three-frequency deionization geometric combination values ​​of each satellite using the least squares criterion to obtain multiple sets of initial coefficients corresponding to each satellite; and to take the average value of the multiple sets of initial coefficients corresponding to each satellite to obtain the coefficient set corresponding to each satellite.

[0129] In this embodiment of the invention, the device further includes an acquisition unit 17 and a judgment unit 18.

[0130] The acquisition unit 17 is used to acquire the next data arc segment and determine the next data arc segment as the current data arc segment.

[0131] The judgment unit 18 is used to determine whether the arc length of the current data arc is greater than or equal to the set length threshold; if so, the matching unit 12 is triggered to continue to execute the step of matching the corresponding first coefficient group according to the harmonic function coefficient table and determining the first coefficient group as the initial value of the fitting coefficient group, until all data arcs are fitted; if not, the determination unit 16 is triggered to continue to execute the step of determining the pre-set second coefficient group as the initial value of the fitting coefficient group, until all data arcs are fitted.

[0132] In the embodiment of the present invention, the observation data of each satellite collected by multiple observation stations for a specified time period are calculated to generate a harmonic function coefficient table. If the arc length of the current data arc is greater than or equal to a set length threshold, the corresponding first coefficient group is matched according to the harmonic function coefficient table, and the first coefficient group is determined as the initial value of the fitting coefficient group. The current data arc is fitted with least squares using the initial value of the fitting coefficient group to obtain the satellite inter-frequency clock deviation fitting value of the current data arc, so as to eliminate the positioning calculation error, reduce the amount of data processing, and improve the fitting timeliness and the accuracy of the fitting results.

[0133] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer device, specifically, a computer device can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0134] This invention provides a computer device including a memory and a processor. The memory stores information including program instructions, and the processor controls the execution of the program instructions. When the program instructions are loaded and executed by the processor, they implement the steps of the above-described embodiment of the global navigation satellite system inter-frequency clock offset estimation method. For a detailed description, please refer to the above-described embodiment of the global navigation satellite system inter-frequency clock offset estimation method.

[0135] The following is for reference. Figure 10 It shows a schematic diagram of the structure of a computer device 600 suitable for implementing the embodiments of this application.

[0136] like Figure 10 As shown, the computer device 600 includes a central processing unit (CPU) 601, which can perform various appropriate tasks and processes according to programs stored in read-only memory (ROM) 602 or programs loaded from storage section 608 into random access memory (RAM) 603. The RAM 603 also stores various programs and data required for the operation of the computer device 600. The CPU 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0137] The following components are connected to I / O interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including a cathode ray tube (CRT), liquid crystal feedback (LCD), etc., and speakers, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card, modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to I / O interface 605 as needed. A removable medium 611, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 610 as needed so that computer programs read from it can be installed in storage section 608 as needed.

[0138] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program including program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 609, and / or installed from removable medium 611.

[0139] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0140] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0141] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0142] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0143] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0144] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0145] The acquisition, storage, use, and processing of data in this application all comply with the relevant provisions of national laws and regulations.

[0146] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0147] This application can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0148] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0149] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for estimating inter-frequency clock offsets of satellites in a global navigation satellite system, characterized in that, The method includes: The observation data collected from multiple observation stations for each satellite over a specified time period are calculated to generate a harmonic function coefficient table, including: Based on observation data collected from multiple observation stations for a specified time period for each satellite, multiple three-frequency deionization geometric combination values ​​for each satellite are calculated. By using the least squares criterion, multiple geometrically unmatched three-frequency deionization values ​​for each satellite are fitted to obtain multiple sets of initial coefficients for each satellite. The average value of the multiple initial coefficients corresponding to each satellite is taken to obtain the coefficient set corresponding to each satellite; Based on the coefficient groups corresponding to multiple satellites, a harmonic function coefficient table is generated; If the arc length of the current data arc segment is greater than or equal to the set length threshold, the corresponding first coefficient group is matched according to the harmonic function coefficient table, and the first coefficient group is determined as the initial value of the fitting coefficient group. The satellite inter-frequency clock offset fitting value for the current data arc segment is obtained by performing least-squares fitting on the current data arc segment using the initial values ​​of the fitting coefficient set, thereby eliminating positioning calculation errors.

2. The method for estimating inter-frequency clock offsets of global navigation satellite systems according to claim 1, characterized in that, Before matching the corresponding first coefficient group according to the harmonic function coefficient table if the arc length of the current data arc segment is greater than or equal to the set length threshold, the method further includes: Based on the visual status of the received satellite signals, the initial data arc is divided into multiple continuous data arcs; Each continuous data arc segment is subjected to cycle slip detection and repair processing to obtain multiple repaired data arc segments.

3. The method for estimating inter-frequency clock offsets of global navigation satellite systems according to claim 1, characterized in that, The method further includes: If the arc length of the current data segment is less than the set length threshold, the pre-set second coefficient group will be determined as the initial value of the fitting coefficient group.

4. The method for estimating inter-frequency clock offsets of a global navigation satellite system according to claim 3, characterized in that, After performing least-squares fitting on the current data arc segment using the initial values ​​of the fitting coefficient set to obtain the satellite inter-frequency clock offset fitting value for the current data arc segment, the method further includes: Obtain the next data arc segment and determine the next data arc segment as the current data arc segment; Determine whether the arc length of the current data arc segment is greater than or equal to the set length threshold; If so, continue to execute the steps of matching the corresponding first coefficient group according to the harmonic function coefficient table and determining the first coefficient group as the initial value of the fitting coefficient group, until all data arcs are fitted. If not, continue with the step of determining the pre-set second coefficient group as the initial value of the fitting coefficient group until all data segments are fitted.

5. A device for estimating inter-frequency clock offsets of a global navigation satellite system, characterized in that, The device includes: The generation unit is used to calculate the observation data of each satellite collected by multiple observation stations for a specified time period and generate a harmonic function coefficient table. The matching unit is used to match the corresponding first coefficient group according to the harmonic function coefficient table if the arc length of the current data arc segment is greater than or equal to the set length threshold, and to determine the first coefficient group as the initial value of the fitting coefficient group. The fitting unit is used to perform least-squares fitting on the current data arc segment using the initial values ​​of the fitting coefficient set, so as to obtain the satellite inter-frequency clock deviation fitting value of the current data arc segment and eliminate the positioning solution error. The generation unit is specifically used to calculate multiple three-frequency ionospheric de-geometric combination values ​​for each satellite based on observation data collected by multiple observation stations for a specified time period; to fit the multiple three-frequency ionospheric de-geometric combination values ​​for each satellite using the least squares criterion to obtain multiple sets of initial coefficients corresponding to each satellite; to take the average of the multiple sets of initial coefficients corresponding to each satellite to obtain the coefficient set corresponding to each satellite; and to generate a harmonic function coefficient table based on the coefficient sets corresponding to multiple satellites.

6. The global navigation satellite system inter-frequency clock offset estimation device according to claim 5, characterized in that, The device further includes: The segmentation unit is used to divide the received initial data arc into multiple continuous data arcs according to the visibility of the received satellite signal; The processing unit is used to perform cycle slip detection and repair processing on each of the continuous data arc segments to obtain multiple repaired data arc segments.

7. The global navigation satellite system inter-frequency clock offset estimation device according to claim 5, characterized in that, The device further includes: The determining unit is used to determine the pre-set second coefficient group as the initial value of the fitting coefficient group if the arc length of the current data arc segment is less than the set length threshold.

8. The global navigation satellite system inter-frequency clock offset estimation device according to claim 7, characterized in that, The device further includes: An acquisition unit is used to acquire the next data arc segment and determine the next data arc segment as the current data arc segment; The judgment unit is used to determine whether the arc length of the current data arc segment is greater than or equal to a set length threshold; if so, the matching unit is triggered to continue executing the step of matching the corresponding first coefficient group according to the harmonic function coefficient table and determining the first coefficient group as the initial value of the fitting coefficient group, until all data arc segments are fitted; if not, the determination unit is triggered to continue executing the step of determining the pre-set second coefficient group as the initial value of the fitting coefficient group, until all data arc segments are fitted.

9. A computer-readable medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the global navigation satellite system satellite inter-frequency clock offset estimation method as described in any one of claims 1 to 4.

10. A computer device comprising a memory and a processor, the memory for storing information including program instructions, and the processor for controlling the execution of the program instructions, characterized in that, When the program instructions are loaded and executed by the processor, they implement the global navigation satellite system satellite inter-frequency clock offset estimation method according to any one of claims 1 to 4.

11. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements the global navigation satellite system satellite inter-frequency clock offset estimation method according to any one of claims 1 to 4.

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