A method for determining the accuracy of raw observations from a spaceborne GNSS receiver

Abstract

This invention relates to a method for determining the accuracy of raw observations from a spaceborne GNSS receiver. The method involves preprocessing the raw observation data file, selecting pseudorange and carrier phase data that meet predetermined conditions as test channel data and reference channel data, calculating their temporal intersection, performing cross-difference on each segment of raw observation data, and then performing triple or quadruple difference. The root mean square of each segment of raw observation data for each channel is statistically analyzed and plotted. This method features batch processing capabilities, automatically traversing and matching various satellite channels to obtain all time-segment data that meet predetermined conditions, greatly improving evaluation efficiency, accuracy, and coverage, and outputting visualized evaluation results. Accurate evaluation of pseudorange and carrier phase accuracy is achieved through inter-channel cross-difference and triple or quadruple difference; by selecting different difference orders for static and high-dynamic test scenarios, the need for an additional receiver as a test reference is avoided.

Description

Technical Field

[0001] This invention belongs to the field of satellite navigation, specifically relating to a method for determining the accuracy of raw observations of a spaceborne GNSS receiver. Background Technology

[0002] With the development of GNSS, spaceborne GNSS receivers have become an effective means of high-precision orbit determination for various satellites. They can provide satellites with all-day, all-weather, high-precision position, velocity, and time information. Not only are they highly accurate, but they are also technologically mature, low-cost, and have a wide coverage, leading to their widespread application. As the aerospace field demands increasingly higher accuracy in satellite orbit determination, in addition to real-time orbit determination, post-orbit precision orbit determination is also required. Therefore, extensive simulation tests under various testing scenarios are necessary to ensure that the accuracy of the raw observations (mainly pseudorange and carrier phase values) output by the spaceborne GNSS receiver meets the required specifications.

[0003] Currently, the real-time positioning / orbit determination accuracy assessment of spaceborne GNSS receivers mainly involves comparing the positioning / orbit determination results output by the GNSS receiver with the simulated position information from a simulator, calculating the RMS value of the difference, and then using this method primarily to troubleshoot receiver malfunctions, rarely evaluating the raw observations. Assessing the on-orbit accuracy of spaceborne GNSS receivers mainly involves comparing and analyzing the post-hoc precise orbit determination results with the downlinked real-time orbit determination results, calculating the RMS value of the difference. In this orbit determination accuracy assessment method, the post-hoc precise orbit determination serves as the benchmark for position and velocity. The accuracy of the raw observations is one of the most important determinants of the post-hoc precise orbit determination accuracy, directly determining not only the accuracy of the post-hoc precise orbit determination but also indirectly determining the accuracy and reliability of the on-orbit accuracy assessment.

[0004] After the development of a spaceborne GNSS receiver is completed, the evaluation of the accuracy of the raw observations is a crucial step. Currently, there are two main evaluation methods: one is to perform zero-baseline measurements using a reference receiver and the receiver under test, and the other is to perform double-difference measurements using the receiver and a simulator. Both methods involve double-difference processing, which cannot meet the accuracy evaluation requirements of carrier phase for spaceborne receivers with acceleration and jerk. Furthermore, they require additional receivers, resulting in high hardware costs and testing complexity. The specific implementation of these two methods involves opening the data file, randomly selecting a segment of valid raw observation data (pseudorange or carrier phase value) at a specific frequency point of a certain channel of the receiver, then manually interpreting and searching for valid data from other channels within the same time period. The difference between the two data points is then performed again using double-difference processing, and finally, statistical analysis is conducted using data processing tools. This method has several shortcomings in its implementation: it cannot eliminate the effects of jerk, leading to inaccurate assessment of the precision of the raw observations; due to the large volume of observation files, opening the data files using ordinary data processing software requires a long loading time, and manual interpretation and filtering of valid data are necessary, resulting in low processing efficiency and a high risk of errors; the large number of satellite channels makes it impossible to evaluate the precision of the raw observations across all channels; and the numerous test scenarios and data files contribute to low processing efficiency. Therefore, to improve the efficiency and accuracy of raw observation assessment while also increasing its coverage, it is necessary to improve the implementation method for assessing the precision of raw observations. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a method for determining the raw observation accuracy of a spaceborne GNSS receiver, which addresses the shortcomings of existing technologies. This method enables automatic evaluation of the raw observation accuracy of the spaceborne GNSS receiver, while also having batch processing capabilities to improve evaluation efficiency, accuracy, and coverage, and outputs evaluation results.

[0006] The technical solution of this invention is: a method for determining the raw observation accuracy of a spaceborne GNSS receiver, wherein the spaceborne GNSS receiver comprises Y satellite navigation systems, each satellite navigation system comprises M frequency points, and each frequency point corresponds to K channels; Y≥1, M≥1, K>1; a raw observation data file stores the M*K channel data corresponding to each frequency point of one system. The method for determining the raw observation accuracy of a static observation scenario includes the following steps:

[0007] S1. Select the original observation data file, perform data preprocessing, and obtain continuous observation data of pseudorange and carrier phase for each satellite channel at each frequency point. The obtained continuous observation data of pseudorange is within the pseudorange threshold range, and the continuous observation data of carrier phase does not contain continuous zero values.

[0008] S2. For the currently selected frequency point, select one channel as the reference channel and the other K-1 channels as test channels. According to the satellite orbit type, select the pseudorange and carrier phase data of the reference channel from the preprocessed data of the original observation data file as the reference channel data, and select the pseudorange and carrier phase data of the other K-1 channels from the preprocessed data of the original observation data file as the test channel data.

[0009] S3. For the current test channel, search for the time intersection between the baseline channel data and the current test channel data, and filter the data segments that meet the time length threshold within the time intersection to obtain the number of data segments N and the start and end times of each data segment;

[0010] S4. Perform cross-difference between the reference channel data and the test channel data in the current data segment, and then perform triple difference to obtain the triple difference array PrD3 of pseudorange observations and the triple difference array CpD3 of carrier phase observations.

[0011] S5. Calculate the root mean square X of the pseudorange of the current data segment in the current test channel based on the triple difference array PrD3 of the pseudorange observations. RMS Standard deviation X std The root mean square X of the carrier phase of the current data segment in the current test channel is calculated based on the three-difference array CpD3 of the carrier phase observations. RMS Standard deviation X std ;

[0012] S6. Repeat S4 to S5 to obtain the root mean square pseudorange X of the N data segments of the current test channel. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std And output the plot;

[0013] S7. Repeat steps S3 to S6 to obtain the pseudo-range root mean square X of N data segments for all test channels at the currently selected frequency point. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std ;

[0014] S8. Repeat steps S2 to S7 to obtain the root mean square pseudorange X of N data segments for all test channels at all frequency points. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std ;

[0015] S9. Repeat S1 to S8 to obtain the pseudo-range root mean square X of N data segments for all test channels at all frequencies in all original observation data files.RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std This serves as the output of the raw observation accuracy of the spaceborne GNSS receiver.

[0016] Furthermore, the data preprocessing described in S1 includes: skipping data segments of specified length and data segments with specified start and end times in the original observation data file; filtering the pseudorange and carrier phase values ​​in the original observation data file; the filtering principle is: setting pseudorange threshold intervals according to the different orbital altitudes of different navigation satellites; filtering out pseudorange observation data within the pseudorange threshold interval; and removing data segments in the original observation data file where the carrier phase value has consecutive zero values.

[0017] Furthermore, the selection principle of the reference channel in S2 is as follows: the validity of each channel data is pre-judged sequentially, and there is valid data and the length of at least one continuous data segment meets the time length threshold; the validity includes: pseudorange observation data is within the pseudorange threshold range, and carrier phase observation data does not contain continuous zero values.

[0018] Furthermore, the triple difference array PrD3 of the pseudorange observations and the triple difference array CpD3 of the carrier phase observations obtained in S4 specifically include:

[0019] Step 41: Perform cross-difference between the baseline channel data and the test channel data in the current data segment:

[0020] △Pr i =Pr ij -Pr ik

[0021] △Cp i =Cp ij -Cp ik

[0022] In the formula, △Pr i Let △Cp represent the cross difference array of pseudorange observations obtained in the i-th data segment. i This represents the cross-difference array of carrier phase observations obtained within the i-th data segment, where i is the data segment number, ranging from 1 to N; Pr ij Pr represents an array consisting of all pseudorange observations in the i-th data segment of the reference channel. ik Cp represents the array consisting of all pseudorange observations of the k-th test channel within the i-th data segment; ij Cp represents the array consisting of all carrier phase observations in the i-th data segment of the reference channel. ik Let k represent the array of all carrier phase observations in the i-th data segment of the k-th test channel, where k = 1, 2, ..., K, and k ≠ j;

[0023] Step 42: Perform cross-difference array ΔPr of pseudorange observations i The cross-difference array △Cp between carrier phase observations i Perform three-difference processing separately;

[0024] The single difference PrD1(n1), double difference PrD2(n2), and triple difference PrD3(n3) of pseudorange observations are expressed as follows:

[0025] PrD1(n1)=△Pri(n1+1)-△Pri(n1);

[0026] PrD2(n2)=PrD1(n2+1)-PrD1(n2);

[0027] PrD3(n3)=PrD2(n3+1)-PrD2(n3);

[0028] Where n1 ranges from 1 to D1-1, and D1 is the number of pseudorange observations contained in the current data segment; D1-1 PrD1(n1) constitute the single difference array PrD1 of the pseudorange observations;

[0029] The value of n2 ranges from 1 to D1-2. D1-2 PrD2(n2) constitute the double difference array PrD2 of the pseudorange observations.

[0030] The value of n3 ranges from 1 to D1-3. D1-3 PrD3(n3) constitute the three-difference array PrD3 of the pseudorange observations.

[0031] The single difference CpD1(n5), double difference CpD2(n6), and triple difference CpD3(n7) of the carrier phase observations are expressed as follows:

[0032] CpD1(n5)=△Cpi(n5+1)-△Cpi(n5);

[0033] CpD2(n6)=CpD1(n6+1)-CpD1(n6);

[0034] CpD3(n7)=CpD2(n7+1)-CpD2(n7);

[0035] Wherein, the value of n5 ranges from 1 to D2-1, and D2 is the number of carrier phase observations contained in the current data segment; D2-1 CpD1(n5) constitute the single difference array CpD1 of the carrier phase observations;

[0036] The value of n6 ranges from 1 to D2-2. D2-2 CpD2(n6) constitute the double difference array CpD2 of the carrier phase observation.

[0037] The value of n7 ranges from 1 to D2-3. D2-3 CpD3(n7) constitute the three-difference array CpD3 of the carrier phase observation.

[0038] Furthermore, the root mean square X of the pseudo-distance described in S5 RMS Standard deviation X std The calculation is as follows:

[0039]

[0040] Where A is the noise figure of the three differences in the observation;

[0041]

[0042] in,

[0043] Furthermore, the root mean square X of the carrier phase mentioned in S5 RMS Standard deviation X std The calculation is as follows:

[0044]

[0045]

[0046] in,

[0047] Furthermore, the method for determining the accuracy of the original observations in a dynamic observation scenario includes the following steps:

[0048] T1. Select the original observation data file, perform data preprocessing, and obtain continuous observation data of pseudorange at each frequency point of each satellite channel within the threshold range, and continuous observation data of carrier phase with non-continuous zero values.

[0049] T2. For the currently selected frequency point, select one channel as the reference channel and the other K-1 channels as test channels. According to the satellite orbit type, select the pseudorange and carrier phase data of the reference channel from the preprocessed data of the original observation data file as the reference channel data, and select the pseudorange and carrier phase data of the other K-1 channels from the preprocessed data of the original observation data file as the test channel data.

[0050] T3. For the current test channel, search for the time intersection between the baseline channel data and the current test channel data, and filter the data segments that meet the time length threshold within the time intersection to obtain the number of data segments N and the start and end times of each data segment;

[0051] T4. Perform cross-difference between the reference channel data and the test channel data in the current data segment, and then perform four-difference to obtain the four-difference array PrD4 of pseudorange observations and the four-difference array CpD4 of carrier phase observations.

[0052] T5. Calculate the root mean square (X) of the pseudorange in the current data segment of the current test channel based on the four-difference array PrD4 of the pseudorange observations. RMS Standard deviation X std The root mean square X of the carrier phase of the current data segment in the current test channel is calculated based on the four-difference array CpD4 of the carrier phase observations. RMS Standard deviation X std ;

[0053] T6. Repeat T4 to T5 to obtain the root mean square pseudorange X of the N data segments of the current test channel. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std And output the plot;

[0054] T7. Repeat T3 to T6 to obtain the pseudo-range root mean square X of N data segments for all test channels at the currently selected frequency point. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std ;

[0055] T8. Repeat T2 to T7 to obtain the root mean square pseudorange X of N data segments for all test channels at all frequencies. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std ;

[0056] T9. Repeat T1 to T8 to obtain the pseudo-range root mean square X of N data segments for all test channels at all frequencies in all original observation data files. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std This serves as the output of the raw observation accuracy of the spaceborne GNSS receiver.

[0057] Furthermore, T4 describes obtaining the four-difference array PrD4 of pseudorange observations and the four-difference array CpD4 of carrier phase observations, specifically including:

[0058] Step 41: Perform cross-difference between the baseline channel data and the test channel data in the current data segment:

[0059] △Pr i =Pr ij -Pr ik

[0060] △Cp i =Cpij -Cp ik

[0061] In the formula, △Pr i Let △Cp represent the cross difference array of pseudorange observations obtained in the i-th data segment. i This represents the cross-difference array of carrier phase observations obtained within the i-th data segment, where i is the data segment number, ranging from 1 to N; Pr ij Pr represents an array consisting of all pseudorange observations in the i-th data segment of the reference channel. ik Cp represents the array consisting of all pseudorange observations of the k-th test channel within the i-th data segment; ij Cp represents the array consisting of all carrier phase observations in the i-th data segment of the reference channel. ik Let k represent the array of all carrier phase observations in the i-th data segment of the k-th test channel; where k = 1, 2, ..., K, and k ≠ j.

[0062] Step 42: Perform cross-difference array ΔPr of pseudorange observations i The cross-difference array △Cp between carrier phase observations i Perform four-difference processing separately;

[0063] The single difference PrD1(n1), double difference PrD2(n2), triple difference PrD3(n3), and quadruple difference PrD4(n4) of pseudorange observations are expressed as follows:

[0064] PrD1(n1)=△Pri(n1+1)-△Pri(n1);

[0065] PrD2(n2)=PrD1(n2+1)-PrD1(n2);

[0066] PrD3(n3)=PrD2(n3+1)-PrD2(n3);

[0067] PrD4(n4)=PrD3(n4+1)-PrD3(n4);

[0068] Where n1 ranges from 1 to D1-1, and D1 is the number of pseudorange observations contained in the current data segment; D1-1 PrD1(n1) constitute the single difference array PrD1 of the pseudorange observations;

[0069] The value of n2 ranges from 1 to D1-2. D1-2 PrD2(n2) constitute the double difference array PrD2 of the pseudorange observations.

[0070] The value of n3 ranges from 1 to D1-3. D1-3 PrD3(n3) constitute the three-difference array PrD3 of the pseudorange observations.

[0071] The value of n4 ranges from 1 to D1-4. D1-4 PrD3(n4) constitute the four-difference array PrD4 of the pseudorange observations.

[0072] The single, double, triple, and quadruple differences of carrier phase observations are expressed as follows:

[0073] CpD1(n5)=△Cpi(n5+1)-△Cpi(n5);

[0074] CpD2(n6)=CpD1(n6+1)-CpD1(n6);

[0075] CpD3(n7)=CpD2(n7+1)-CpD2(n7);

[0076] CpD4(n8)=CpD3(n8+1)-CpD3(n8);

[0077] Wherein, the value of n5 ranges from 1 to D2-1, and D2 is the number of carrier phase observations contained in the current data segment; D2-1 CpD1(n5) constitute the single difference array CpD1 of the carrier phase observations;

[0078] The value of n6 ranges from 1 to D2-2. D2-2 CpD2(n6) constitute the double difference array CpD2 of the carrier phase observation.

[0079] The value of n7 ranges from 1 to D2-3. D2-3 CpD3(n7) constitute the three-difference array CpD3 of the carrier phase observation.

[0080] The value of n8 ranges from 1 to D2-4. D2-4 CpD3(n8) constitute the four-difference array CpD4 of the carrier phase observation.

[0081] Furthermore, the root mean square X of the pseudo-distance described in T4 RMS Standard deviation X std The calculation is as follows:

[0082]

[0083] Where B is the noise figure of the four differences in the observations;

[0084]

[0085] in,

[0086] Furthermore, the root mean square X of the carrier phase described in T4 RMS Standard deviation X std The calculation is as follows:

[0087]

[0088]

[0089] in,

[0090] The advantages of this invention compared to the prior art are:

[0091] (1) This method uses the mutual difference between satellite channels, which can reduce testing costs and implementation difficulty without relying on additional hardware facilities such as third-party receivers, thus reducing testing complexity.

[0092] (2) This method can select between three-difference and four-difference methods depending on the test scenario, which can eliminate the influence of acceleration and jerk on the accuracy of pseudorange and carrier phase measurement; no additional receiver is required as a test reference.

[0093] (3) This method has completed the code implementation and can batch process the raw observation files of multiple systems such as GPS and BDS. It can traverse each effective data segment of each satellite channel, automatically statistically analyze the accuracy of pseudorange and carrier phase observations and output the plot. No manual matching of observation data is required, which greatly improves the accuracy evaluation efficiency of raw observations. Attached Figure Description

[0094] Figure 1 Flowchart for automatic evaluation of the accuracy of raw observations;

[0095] Figure 2 GPS L1 pseudorange and carrier phase accuracy assessment results (Satellite 18);

[0096] Figure 3 GPSL2 pseudorange and carrier phase accuracy assessment results (Satellite 18);

[0097] Figure 4 BDS B1 pseudorange and carrier phase accuracy assessment results (Satellite 32). Detailed Implementation

[0098] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0099] This invention provides a method for determining the accuracy of raw observations of a spaceborne GNSS receiver. The spaceborne GNSS receiver includes Y satellite navigation systems, each satellite navigation system includes M frequency points, and each frequency point corresponds to K channels; Y≥1, M≥1, K>1; a raw observation data file stores the M*K channel data corresponding to each frequency point of one system.

[0100] The method described in this invention utilizes code to implement the accuracy assessment function of raw observations from a spaceborne GNSS receiver. It achieves the accuracy assessment of pseudorange and carrier phase through cross-difference and triple or quadruple difference between different channels. It has an automatic batch processing function for raw observation data files; it can automatically traverse and match each satellite channel, and automatically judge and process all time period data that meet the predetermined conditions; it allows setting the difference order, and different difference orders can be selected for static and high-dynamic test scenarios; it does not require an additional receiver as a test benchmark.

[0101] Example 1

[0102] The method flow is as follows: Figure 1 As shown, GNSS static observation data is obtained through the following steps:

[0103] Step 1: Select the original observation data file and perform data preprocessing to obtain continuous observation data of pseudorange and carrier phase for each satellite channel at each frequency point. The obtained continuous observation data of pseudorange is within the pseudorange threshold range, and the continuous observation data of carrier phase does not contain continuous zero values.

[0104] Step 2: For the currently selected frequency point, select one channel as the reference channel and the other K-1 channels as test channels. According to the satellite orbit type, select the pseudorange and carrier phase data of the reference channel from the preprocessed data of the original observation data file as the reference channel data, and select the pseudorange and carrier phase data of the other K-1 channels from the preprocessed data of the original observation data file as the test channel data; where K is the total number of channels under the currently selected frequency point.

[0105] The selection principle of the reference channel in this invention is as follows: the validity of each channel data is pre-judged sequentially, and there is valid data and the length of at least one continuous data segment meets the time length threshold (the time length threshold can be set to ThDl = 1800s in static test scenarios); the validity includes: pseudorange observation data is within the pseudorange threshold range, and carrier phase observation data does not contain continuous zero values.

[0106] Data preprocessing primarily involves filtering pseudorange and carrier phase values ​​from the raw observation data files, selecting all continuous observation data that meet preset conditions for each satellite channel and frequency point. During data preprocessing, specified data lengths or start and end times can be skipped. Based on orbit type, navigation satellites are classified as MEO, GEO, and IGSO, with orbital altitudes of 2×10⁻⁶. 4 km, 3.6×10 4 km, 3.6×10 4 The value of the MEO pseudorange is typically 2 × 10 km. 4 ~2.6×10 4km, the pseudorange values ​​for GEO and IGSO are typically in the range of 3.6 × 10. 4 ~4.15×10 4 km, the pseudorange threshold can be set to ThPr = [1.8 × 10 4 ~4.2×10 4 [km], and the pseudorange observation data within the pseudorange threshold range are obtained by filtering; the carrier phase value can be positive or negative, and can also be zero, but the effective data will not have multiple consecutive zero values, so the data segments with multiple consecutive zero values ​​in the carrier phase value are filtered out.

[0107] To eliminate the influence of channel noise, the test channel and reference channel data are cross-subtracted, but the temporal consistency of the two must be guaranteed; the data must be from the same time point. The pseudorange threshold for the reference channel data is set to ThPr = [1.8 × 10⁻⁶]. 4 ~4.2×10 4 km).

[0108] Step 3: For the current test channel, search for the time intersection between the baseline channel data and the current test channel data, and filter the data segments that meet the time length threshold within the time intersection to obtain the number of data segments N and the start and end times of each data segment.

[0109] For observation data at a certain frequency, starting from the first test channel, the system iterates through all subsequent test channels to search for any temporal intersection with the baseline channel, obtaining all data segments that meet the time length threshold. The number of data segments is denoted as N, and the start and end numbers of each segment are denoted as [Tsi, Tei], i = 1 to N. The time length threshold is typically set according to different test scenarios; for static testing, ThDl = 1800s.

[0110] Step 4: Perform cross-difference between the reference channel data and the test channel data in the current data segment, and then perform triple difference to obtain the triple difference array PrD3 of the pseudorange observations and the triple difference array CpD3 of the carrier phase observations.

[0111] Step 41: First, perform cross-difference between the reference channel data and the test channel data in the current data segment. After selecting a certain frequency point, the cross-difference results of the pseudorange and carrier phase in the current data segment can be expressed as follows:

[0112] △Pr i =Pr ij -Pr ik

[0113] △Cp i =Cp ij -Cp ik

[0114] In the formula, △Pr iLet △Cp represent the cross difference array of pseudorange observations obtained in the i-th data segment. i This represents the cross-difference array of carrier phase observations obtained within the i-th data segment, where i represents the data segment number, ranging from 1 to N; j is the reference channel, and k is the current test channel, k = 1, 2, ..., K, and k ≠ j; Pr ij Pr represents an array consisting of all pseudorange observations in the i-th data segment of the reference channel. ik Cp represents the array consisting of all pseudorange observations of the k-th test channel within the i-th data segment; ij Cp represents the array consisting of all carrier phase observations in the i-th data segment of the reference channel. ik This represents an array consisting of all carrier phase observations for the k-th test channel within the i-th data segment.

[0115] Step 42: Calculate the cross difference array ΔPr of the pseudorange observations. i The cross-difference array △Cp between carrier phase observations i Three-dimensional processing was performed separately to eliminate the influence of acceleration.

[0116] The single, double, and triple differences of pseudorange observations are expressed as follows:

[0117] PrD1(n1)=△Pri(n1+1)-△Pri(n1);

[0118] PrD2(n2)=PrD1(n2+1)-PrD1(n2);

[0119] PrD3(n3)=PrD2(n3+1)-PrD2(n3);

[0120] Where n1 ranges from 1 to D1-1, and D1 is the number of pseudorange observations contained in the current data segment; D1-1 PrD1(n1) constitute the single difference array PrD1 of the pseudorange observations;

[0121] The value of n2 ranges from 1 to D1-2. D1-2 PrD2(n2) constitute the double difference array PrD2 of the pseudorange observations.

[0122] The value of n3 ranges from 1 to D1-3. D1-3 PrD3(n3) constitute the triple difference array PrD3 of the pseudorange observations. The single difference, double difference, and triple difference of the carrier phase observations are expressed as follows:

[0123] CpD1(n5)=△Cpi(n5+1)-△Cpi(n5);

[0124] CpD2(n6)=CpD1(n6+1)-CpD1(n6);

[0125] CpD3(n7)=CpD2(n7+1)-CpD2(n7);

[0126] Wherein, the value of n5 ranges from 1 to D2-1, and D2 is the number of carrier phase observations contained in the current data segment; D2-1 CpD1(n5) constitute the single difference array CpD1 of the carrier phase observations;

[0127] The value of n6 ranges from 1 to D2-2. D2-2 CpD2(n6) constitute the double difference array CpD2 of the carrier phase observation.

[0128] The value of n7 ranges from 1 to D2-3. D2-3 CpD3(n7) constitute the three-difference array CpD3 of the carrier phase observation.

[0129] Step 5: Calculate the root mean square (X) of the pseudorange of the current data segment in the current test channel based on the triple difference array PrD3 of the pseudorange observations. RMS Standard deviation X std The root mean square X of the carrier phase of the current data segment in the current test channel is calculated based on the three-difference array CpD3 of the carrier phase observations. RMS Standard deviation X std .

[0130] X of pseudorange RMS Value and standard deviation X std The calculation formula is as follows:

[0131]

[0132] Where A is the noise figure of the three differences in the observations, with a value of

[0133]

[0134] in,

[0135] X of carrier phase RMS Value and standard deviation X std The calculation formula is as follows:

[0136]

[0137]

[0138] in,

[0139] This embodiment provides a method for calculating the observed triple-difference noise figure A:

[0140] Assuming the observation sequence of the current data segment is: [a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 a10…], then the observation sequence obtained by the pseudorange and carrier phase three differences is: [a3-3a2+3a1-a0 a4-3a3+3a2-a1a5-3a4+3a3-a2…];

[0141] Therefore, the coefficients of each polynomial in the observation sequence obtained by the three-difference method are 1, -3, 3, -1 in sequence. Thus, the noise coefficient of the three-difference observations is... Step 6: Repeat steps 4 and 5 to obtain the root mean square pseudorange X of the N data segments of the current test channel. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std And output the plot.

[0142] Step 7: Repeat steps 3 to 6 to obtain the root mean square pseudorange X of N data segments for all test channels at the currently selected frequency point. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std .

[0143] Step 8: Repeat steps 2 through 7 to obtain the root mean square pseudorange X of N data segments for all test channels at all frequency points. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std .

[0144] Step 9: Repeat steps 1 to 8 to obtain the root mean square pseudorange X of N data segments for all test channels at all frequencies in all original observation data files. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std This serves as the output of the raw observation accuracy of the spaceborne GNSS receiver.

[0145] Example 2

[0146] For GNSS dynamic observation data, the specific steps are as follows:

[0147] Step 1: Select the original observation data file and perform data preprocessing. Filter the pseudorange and carrier phase values ​​in the original observation data file to obtain continuous observation data of pseudorange and carrier phase for each satellite channel at each frequency point. The obtained continuous observation data of pseudorange is within the pseudorange threshold range, and the continuous observation data of carrier phase does not contain continuous zero values.

[0148] Step 2: For the currently selected frequency point, select one channel as the reference channel and the other K-1 channels as test channels. According to the satellite orbit type, select the pseudorange and carrier phase data of the reference channel from the preprocessed data of the original observation data file as the reference channel data, and select the pseudorange and carrier phase data of the other K-1 channels from the preprocessed data of the original observation data file as the test channel data; where K is the total number of channels under the currently selected frequency point.

[0149] The selection principle for the baseline channel is to sequentially pre-judge the validity of each channel's data, ensuring that there is valid data and that at least one segment of continuous data meets the data length threshold (the data length threshold can be set to ThDl = 300s in dynamic test scenarios).

[0150] Data preprocessing primarily involves filtering pseudorange and carrier phase values ​​from the raw observation data files, selecting all continuous observation data that meet preset conditions for each satellite channel and frequency point. During data preprocessing, specified data lengths or start and end times can be skipped. Based on orbit type, navigation satellites are classified as MEO, GEO, and IGSO, with orbital altitudes of 2×10⁻⁶. 4 km, 3.6×10 4 km, 3.6×10 4 The value of the MEO pseudorange is typically 2 × 10 km. 4 ~2.6×10 4 km, the pseudorange values ​​for GEO and IGSO are typically in the range of 3.6 × 10. 4 ~4.15×10 4 km, the pseudorange threshold can be set to ThPr = [1.8 × 10 4 ~4.2×10 4 [km], and the pseudorange observation data within the pseudorange threshold range are obtained by filtering; the carrier phase value can be positive or negative, and can also be zero, but the effective data will not have multiple consecutive zero values, so the data segments with multiple consecutive zero values ​​in the carrier phase value are filtered out.

[0151] To eliminate the influence of channel noise, the test channel and reference channel data are cross-subtracted, but the temporal consistency of the two must be guaranteed; the data must be from the same time point. The pseudorange threshold for the reference channel data is set to ThPr = [1.8 × 10⁻⁶]. 4~4.2×10 4 km).

[0152] Step 3: For the current test channel, search for the time intersection between the baseline channel data and the current test channel data, and filter the data segments that meet the time length threshold within the time intersection to obtain the number of data segments N and the start and end times of each data segment.

[0153] For observation data at a certain frequency, starting from the first test channel, the system iterates through all subsequent test channels to search for any temporal intersection with the baseline channel, obtaining all data segments that meet the time length threshold. The number of data segments is denoted as N, and the start and end numbers of each segment are denoted as [Tsi, Tei], i = 1 to N. The data time length threshold is typically set according to different test scenarios; for low-Earth orbit dynamic scenarios, ThDl = 300s is usually sufficient.

[0154] Step 4: Perform cross-difference between the reference channel data and the test channel data in the current data segment, and then perform four-difference to obtain the four-difference array PrD4 of pseudorange observations and the four-difference array CpD4 of carrier phase observations.

[0155] Step 41: First, perform cross-difference between the reference channel data and the test channel data in the current data segment. After selecting a certain frequency point, the cross-difference results of the pseudorange and carrier phase in the current data segment can be expressed as follows:

[0156] △Pr i =Pr ij -Pr ik

[0157] △Cp i =Cp ij -Cp ik

[0158] In the formula, △Pr i Let △Cp represent the cross difference array of pseudorange observations obtained in the i-th data segment. i This represents the cross-difference array of carrier phase observations obtained within the i-th data segment, where i represents the data segment number, ranging from 1 to N; j is the reference channel, and k is the current test channel, k = 1, 2, ..., K, and k ≠ j; Pr ij Pr represents an array consisting of all pseudorange observations in the i-th data segment of the reference channel. ik Cp represents the array consisting of all pseudorange observations of the k-th test channel within the i-th data segment; ij Cp represents the array consisting of all carrier phase observations in the i-th data segment of the reference channel. ik This represents an array consisting of all carrier phase observations for the k-th test channel within the i-th data segment.

[0159] Step 42: Calculate the cross difference array ΔPr of the pseudorange observations. i The cross-difference array △Cp between carrier phase observations i Four different processing steps were performed separately to eliminate the influence of jerk.

[0160] The single, double, triple, and quadruple differences of pseudorange observations are expressed as follows:

[0161] PrD1(n1)=△Pri(n1+1)-△Pri(n1);

[0162] PrD2(n2)=PrD1(n2+1)-PrD1(n2);

[0163] PrD3(n3)=PrD2(n3+1)-PrD2(n3);

[0164] PrD4(n4)=PrD3(n4+1)-PrD3(n4);

[0165] Where n1 ranges from 1 to D1-1, and D1 is the number of pseudorange observations contained in the current data segment; D1-1 PrD1(n1) constitute the single difference array PrD1 of the pseudorange observations;

[0166] The value of n2 ranges from 1 to D1-2. D1-2 PrD2(n2) constitute the double difference array PrD2 of the pseudorange observations.

[0167] The value of n3 ranges from 1 to D1-3. D1-3 PrD3(n3) constitute the three-difference array PrD3 of the pseudorange observations.

[0168] The value of n4 ranges from 1 to D1-4. D1-4 PrD3(n4) constitute the four-difference array PrD4 of the pseudorange observations.

[0169] The single, double, triple, and quadruple differences of carrier phase observations are expressed as follows:

[0170] CpD1(n5)=△Cpi(n5+1)-△Cpi(n5);

[0171] CpD2(n6)=CpD1(n6+1)-CpD1(n6);

[0172] CpD3(n7)=CpD2(n7+1)-CpD2(n7);

[0173] CpD4(n8)=CpD3(n8+1)-CpD3(n8);

[0174] Wherein, the value of n5 ranges from 1 to D2-1, and D2 is the number of carrier phase observations contained in the current data segment; D2-1 CpD1(n5) constitute the single difference array CpD1 of the carrier phase observations;

[0175] The value of n6 ranges from 1 to D2-2. D2-2 CpD2(n6) constitute the double difference array CpD2 of the carrier phase observation.

[0176] The value of n7 ranges from 1 to D2-3. D2-3 CpD3(n7) constitute the three-difference array CpD3 of the carrier phase observation.

[0177] The value of n8 ranges from 1 to D2-4. D2-4 CpD3(n8) constitute the four-difference array CpD4 of the carrier phase observation.

[0178] Step 5: Calculate the root mean square (X) of the pseudorange of the current data segment in the current test channel based on the four-difference array PrD4 of the pseudorange observations. RMS Standard deviation X std The root mean square X of the carrier phase of the current data segment in the current test channel is calculated based on the four-difference array CpD4 of the carrier phase observations. RMS Standard deviation X std .

[0179] X of pseudorange RMS Value and standard deviation X std The calculation formula is as follows:

[0180]

[0181] Where B is the noise figure of the four differences in the observations, with a value of

[0182]

[0183] in,

[0184] X of carrier phase RMS Value and standard deviation X std The calculation formula is as follows:

[0185]

[0186]

[0187] in,

[0188] This embodiment provides a method for calculating the four-difference noise figure B of the observed data:

[0189] Assuming the observation sequence of the current data segment is: [a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 a10…], then the observation sequence obtained from the pseudorange and carrier phase four-differences is: [a4-4a3+6a2-4a1+a0a5-4a4+6a3-4a2+a1…]. It can be seen that the coefficients of each polynomial in the four-differences observation sequence are, in order, 1, -4, 6, -4, 1. Therefore, the four-differences noise figure for the observations…

[0190]

[0191] Step 6: Repeat steps 4 and 5 to obtain the root mean square pseudorange X of the N data segments of the current test channel. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std And output the plot.

[0192] Step 7: Repeat steps 3 to 6 to obtain the root mean square pseudorange X of N data segments for all test channels at the currently selected frequency point. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std .

[0193] Step 8: Repeat steps 2 through 7 to obtain the root mean square pseudorange X of N data segments for all test channels at all frequency points. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std .

[0194] Step 9: Repeat steps 1 to 8 to obtain the root mean square pseudorange X of N data segments for all test channels at all frequencies in all original observation data files. RMS Standard deviation X std Carrier phase root mean square X RMS Standard deviation X std This serves as the output of the raw observation accuracy of the spaceborne GNSS receiver.

[0195] The accuracy of raw observations is one of the most important determinants of the accuracy of post-precision orbit determination. It not only directly determines the accuracy of post-precision orbit determination but also indirectly determines the accuracy and reliability of on-orbit accuracy assessment. Using this method to determine the accuracy of raw observations from the spaceborne GNSS receiver provides a reliable basis and guidance for determining the accuracy of post-precision orbit determination and for on-orbit accuracy assessment.

[0196] The method described in this invention achieves accurate assessment of pseudorange and carrier phase accuracy through inter-channel cross-difference and triple or quadruple cross-difference; it automatically traverses and matches each satellite channel, and automatically judges and processes all time-period data that meet predetermined conditions. By setting the difference order, the accuracy of the raw observations from the spaceborne GNSS receiver can be determined for both static and high-dynamic test scenarios.

[0197] The invention is further illustrated below with specific numerical values. Taking GPS and BDS systems as examples, assuming the onboard GNSS receiver is in dynamic mode, the GNSS signal simulator is set to dual-system dual-frequency mode (GPS L1, L2 and BDS B1I, B3I), the user receiver's orbital altitude is 600km, the radio frequency signal is input to the GNSS receiver, and the raw observation data output by the receiver is saved. The accuracy of the raw observation data (pseudorange and carrier phase values) is evaluated using the method provided by this invention. The specific steps are as follows:

[0198] Step 1: Select the data file and run the code;

[0199] Step 2: The code will complete data preprocessing, filter test channel and benchmark channel data, perform cross-difference, triple difference and quadruple difference operations, calculate RMS and standard deviation, plot output, and traverse all channel data.

[0200] Step 3: View the evaluation results. You can see the pseudorange and carrier phase accuracy evaluations saved as text and images in the corresponding folder.

[0201] From the example Figure 2 , 3 As can be seen from Figure 4, the L1 pseudorange and carrier phase accuracy of GPS satellite 18 are approximately 15cm and 1mm, respectively; the L1 pseudorange and carrier phase accuracy of GPS satellite 18 are approximately 2.2cm and 1.3mm, respectively; the B1 pseudorange and carrier phase accuracy of BDS satellite 32 are approximately 4.5cm and 0.76mm, respectively (all figures are root mean square). RMS value).

Claims

1. A method for determining the accuracy of raw observations of a spaceborne GNSS receiver, wherein the spaceborne GNSS receiver comprises Y satellite navigation systems, each satellite navigation system comprises M frequency points, and each frequency point corresponds to K channels; Y≥1, M≥1, K>1; a raw observation data file stores M*K channel data corresponding to each frequency point of one system; characterized in that, The method for determining the accuracy of raw observations in static observation scenarios includes the following steps: S1. Select the original observation data file, perform data preprocessing, and obtain continuous observation data of pseudorange and carrier phase for each satellite channel at each frequency point. The obtained continuous observation data of pseudorange is within the pseudorange threshold range, and the continuous observation data of carrier phase does not contain continuous zero values. S2. For the currently selected frequency point, select one channel as the reference channel and the other K-1 channels as test channels. According to the satellite orbit type, select the pseudorange and carrier phase data of the reference channel from the preprocessed data of the original observation data file as the reference channel data, and select the pseudorange and carrier phase data of the other K-1 channels from the preprocessed data of the original observation data file as the test channel data. S3. For the current test channel, search for the time intersection between the baseline channel data and the current test channel data, and filter the data segments that meet the time length threshold within the time intersection to obtain the number of data segments N and the start and end times of each data segment; S4. Perform cross-difference between the reference channel data and the test channel data in the current data segment, and then perform triple difference to obtain the triple difference array PrD3 of pseudorange observations and the triple difference array CpD3 of carrier phase observations. S5. Calculate the root mean square Pr of the pseudorange of the current data segment in the current test channel based on the triple difference array PrD3 of the pseudorange observations. RMS Standard deviation Pr STD The root mean square Cp of the carrier phase of the current data segment in the current test channel is calculated based on the triple difference array CpD3 of the carrier phase observations. RMS Standard deviation Cp STD ; S6. Repeat S4 to S5 to obtain the pseudo-root mean square Pr of the N data segments of the current test channel. RMS Standard deviation Pr STD Carrier phase root mean square Cp RMS Standard deviation Cp STD And output the plot; S7. Repeat steps S3 to S6 to obtain the pseudo-range root mean square Pr of N data segments for all test channels at the currently selected frequency point. RMS Standard deviation Pr STD Carrier phase root mean square Cp RMS Standard deviation Cp STD ; S8. Repeat steps S2 to S7 to obtain the pseudo-range root mean square Pr of N data segments for all test channels at all frequencies. RMS Standard deviation Pr STD Carrier phase root mean square Cp RMS Standard deviation Cp STD ; S9. Repeat S1 to S8 to obtain the pseudo-root mean square (Pr) of the N data segments for all test channels at all frequencies in all original observation data files. RMS Standard deviation Pr STD Carrier phase root mean square Cp RMS Standard deviation Cp STD This serves as the output of the raw observation accuracy of the spaceborne GNSS receiver.

2. The method for determining the accuracy of raw observations of a spaceborne GNSS receiver according to claim 1, characterized in that, S1 describes data preprocessing, which includes: skipping data segments of specified length and data segments with specified start and end times in the original observation data file; filtering pseudorange and carrier phase values ​​in the original observation data file; and filtering based on the following principle: setting pseudorange threshold intervals according to the different orbital altitudes of different navigation satellites, and filtering pseudorange observation data within the pseudorange threshold interval; and removing data segments in the original observation data file where the carrier phase value is consecutively zero.

3. The method for determining the accuracy of raw observations of a spaceborne GNSS receiver according to claim 1, characterized in that, The selection principle of the reference channel in S2 is as follows: the validity of each channel data is pre-judged sequentially, and there is valid data and the length of at least one continuous data segment meets the time length threshold; the validity includes: pseudorange observation data is within the pseudorange threshold range, and carrier phase observation data does not contain continuous zero values.

4. The method for determining the accuracy of raw observations of a spaceborne GNSS receiver according to claim 1, characterized in that, The triple difference array PrD3 for pseudorange observations and the triple difference array CpD3 for carrier phase observations obtained in S4 specifically include: Step 41: Perform cross-difference between the baseline channel data and the test channel data in the current data segment: △Pr i =Pr ij -Pr ik △Cp i =Cp ij -Cp ik In the formula, △Pr i Let △Cp represent the cross difference array of pseudorange observations obtained in the i-th data segment. i This represents the cross-difference array of carrier phase observations obtained within the i-th data segment, where i is the data segment number, ranging from 1 to N; Pr ij Pr represents an array consisting of all pseudorange observations in the i-th data segment of the reference channel. ik Cp represents the array consisting of all pseudorange observations of the k-th test channel within the i-th data segment; ij Cp represents the array consisting of all carrier phase observations in the i-th data segment of the reference channel. ik Let k represent the array of all carrier phase observations in the i-th data segment of the k-th test channel, where k = 1, 2, ..., K, and k ≠ j; Step 42: Perform cross-difference array ΔPr of pseudorange observations i The cross-difference array △Cp between carrier phase observations i Perform three-difference processing separately; The single difference PrD1(n1), double difference PrD2(n2), and triple difference PrD3(n3) of pseudorange observations are expressed as follows: PrD1(n1)=△Pri(n1+1)-△Pri(n1); PrD2(n2)=PrD1(n2+1)-PrD1(n2); PrD3(n3)=PrD2(n3+1)-PrD2(n3); Where n1 ranges from 1 to D1-1, and D1 is the number of pseudorange observations contained in the current data segment; D1-1 PrD1(n1) constitute the single difference array PrD1 of the pseudorange observations; The value of n2 ranges from 1 to D1-2. D1-2 PrD2(n2) constitute the double difference array PrD2 of the pseudorange observations. The value of n3 ranges from 1 to D1-3. D1-3 PrD3(n3) constitute the three-difference array PrD3 of the pseudorange observations. The single difference CpD1(n5), double difference CpD2(n6), and triple difference CpD3(n7) of the carrier phase observations are expressed as follows: CpD1(n5)=△Cpi(n5+1)-△Cpi(n5); CpD2(n6)=CpD1(n6+1)-CpD1(n6); CpD3(n7)=CpD2(n7+1)-CpD2(n7); Wherein, the value of n5 ranges from 1 to D2-1, and D2 is the number of carrier phase observations contained in the current data segment; D2-1 CpD1(n5) constitute the single difference array CpD1 of the carrier phase observations; The value of n6 ranges from 1 to D2-2. D2-2 CpD2(n6) constitute the double difference array CpD2 of the carrier phase observation. The value of n7 ranges from 1 to D2-3. D2-3 CpD3(n7) constitute the three-difference array CpD3 of the carrier phase observation.

5. The method for determining the raw observation accuracy of a spaceborne GNSS receiver according to claim 4, characterized in that, The root mean square Pr of the pseudo-distance mentioned in S5 RMS Standard deviation Pr STD The calculation is as follows: Where A is the noise figure of the three differences in the observation; in, 6. The method for determining the accuracy of raw observations of a spaceborne GNSS receiver according to claim 5, characterized in that, The root mean square Cp of the carrier phase described in S5 RMS Standard deviation Cp STD The calculation is as follows: in, 7. A method for determining the accuracy of raw observations of a spaceborne GNSS receiver, characterized in that, The method for determining the accuracy of raw observations in dynamic observation scenarios includes the following steps: T1. Select the original observation data file, perform data preprocessing, and obtain continuous observation data of pseudorange at each frequency point of each satellite channel within the threshold range, and continuous observation data of carrier phase with non-continuous zero values. T2. For the currently selected frequency point, select one channel as the reference channel and the other K-1 channels as test channels. According to the satellite orbit type, select the pseudorange and carrier phase data of the reference channel from the preprocessed data of the original observation data file as the reference channel data, and select the pseudorange and carrier phase data of the other K-1 channels from the preprocessed data of the original observation data file as the test channel data. T3. For the current test channel, search for the time intersection between the baseline channel data and the current test channel data, and filter the data segments that meet the time length threshold within the time intersection to obtain the number of data segments N and the start and end times of each data segment; T4. Perform cross-difference between the reference channel data and the test channel data in the current data segment, and then perform four-difference to obtain the four-difference array PrD4 of pseudorange observations and the four-difference array CpD4 of carrier phase observations. T5. Calculate the root mean square Pr of the pseudorange of the current data segment in the current test channel based on the four-difference array PrD4 of the pseudorange observations. RMS Standard deviation Pr STD The root mean square Cp of the carrier phase of the current data segment in the current test channel is calculated based on the four-difference array CpD4 of the carrier phase observations. RMS Standard deviation Cp STD ; T6. Repeat T4 to T5 to obtain the pseudo-range root mean square Pr of the N data segments of the current test channel. RMS Standard deviation Pr STD Carrier phase root mean square Cp RMS Standard deviation Cp STD And output the plot; T7. Repeat T3 to T6 to obtain the pseudo-range root mean square Pr of N data segments for all test channels at the currently selected frequency point. RMS Standard deviation Pr STD Carrier phase root mean square Cp RMS Standard deviation Cp STD ; T8. Repeat T2 to T7 to obtain the pseudo-range root mean square Pr of N data segments for all test channels at all frequencies. RMS Standard deviation Pr STD Carrier phase root mean square Cp RMS Standard deviation Cp STD ; T9. Repeat T1 to T8 to obtain the pseudo-range root mean square Pr of N data segments for all test channels at all frequencies in all original observation data files. RMS Standard deviation Pr STD Carrier phase root mean square Cp RMS Standard deviation Cp STD This serves as the output of the raw observation accuracy of the spaceborne GNSS receiver.

8. The method for determining the accuracy of raw observations of a spaceborne GNSS receiver according to claim 7, characterized in that, The four-difference array PrD4 for pseudorange observations and the four-difference array CpD4 for carrier phase observations, as described in T4, specifically include: Step 41: Perform cross-difference between the baseline channel data and the test channel data in the current data segment: △Pr i =Pr ij -Pr ik △Cp i =Cp ij -Cp ik In the formula, △Pr i Let △Cp represent the cross difference array of pseudorange observations obtained in the i-th data segment. i This represents the cross-difference array of carrier phase observations obtained within the i-th data segment, where i is the data segment number, ranging from 1 to N; Pr ij Pr represents an array consisting of all pseudorange observations in the i-th data segment of the reference channel. ik Cp represents the array consisting of all pseudorange observations of the k-th test channel within the i-th data segment; ij Cp represents the array consisting of all carrier phase observations in the i-th data segment of the reference channel. ik Let k represent the array of all carrier phase observations in the i-th data segment of the k-th test channel; where k = 1, 2, ..., K, and k ≠ j. Step 42: Perform cross-difference array ΔPr of pseudorange observations i The cross-difference array △Cp between carrier phase observations i Perform four-difference processing respectively; The single difference PrD1(n1), double difference PrD2(n2), triple difference PrD3(n3), and quadruple difference PrD4(n4) of pseudorange observations are expressed as follows: PrD1(n1)=△Pri(n1+1)-△Pri(n1); PrD2(n2)=PrD1(n2+1)-PrD1(n2); PrD3(n3)=PrD2(n3+1)-PrD2(n3); PrD4(n4)=PrD3(n4+1)-PrD3(n4); Where n1 ranges from 1 to D1-1, and D1 is the number of pseudorange observations contained in the current data segment; D1-1 PrD1(n1) constitute the single difference array PrD1 of the pseudorange observations; The value of n2 ranges from 1 to D1-2. D1-2 PrD2(n2) constitute the double difference array PrD2 of the pseudorange observations. The value of n3 ranges from 1 to D1-3. D1-3 PrD3(n3) constitute the three-difference array PrD3 of the pseudorange observations. The value of n4 ranges from 1 to D1-4. D1-4 PrD3(n4) constitute the four-difference array PrD4 of the pseudorange observations. The single, double, triple, and quadruple differences of carrier phase observations are expressed as follows: CpD1(n5)=△Cpi(n5+1)-△Cpi(n5); CpD2(n6)=CpD1(n6+1)-CpD1(n6); CpD3(n7)=CpD2(n7+1)-CpD2(n7); CpD4(n8)=CpD3(n8+1)-CpD3(n8); Wherein, the value of n5 ranges from 1 to D2-1, and D2 is the number of carrier phase observations contained in the current data segment; D2-1 CpD1(n5) constitute the single difference array CpD1 of the carrier phase observations; The value of n6 ranges from 1 to D2-2. D2-2 CpD2(n6) constitute the double difference array CpD2 of the carrier phase observation. The value of n7 ranges from 1 to D2-3. D2-3 CpD3(n7) constitute the three-difference array CpD3 of the carrier phase observation. The value of n8 ranges from 1 to D2-4. D2-4 CpD3(n8) constitute the four-difference array CpD4 of the carrier phase observation.

9. The method for determining the accuracy of raw observations of a spaceborne GNSS receiver according to claim 8, characterized in that, The root mean square Pr of the pseudo-distance mentioned in T4 RMS Standard deviation Pr STD The calculation is as follows: Where B is the noise figure of the four differences in the observations; in, 10. The method for determining the accuracy of raw observations of a spaceborne GNSS receiver according to claim 9, characterized in that, The root mean square Cp of the carrier phase described in T4 RMS Standard deviation Cp STD The calculation is as follows: in,

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