Beidou virtual reference high-precision positioning method taking ionosphere delay influence into consideration

Abstract

The invention relates to the technical field of Beidou positioning, in particular to a Beidou virtual reference high-precision positioning method taking ionosphere delay influence into consideration. The invention provides a weighting method combined with ionosphere delay influence, which comprises the following steps of: constructing a physical check station, calculating double-difference ionosphere delay # imgabs0 # of the check station relative to a main reference station, and taking a calculation result as a double-difference ionosphere delay reference value; calculating to obtain a double-difference ionosphere delay reference value # imgabs1 # at the construction position of the check station obtained by interpolation of the virtual reference station, and taking the absolute value of the difference value of # imgabs2 # and # imgabs3 # as the ionosphere error of the satellite; compared with the prior art, on the basis of combining the precision of the elevation angle related prior observation value of the double-difference observation value and combining the ionosphere error of the satellite, gross errors caused by ionosphere anomalies can be weakened, and high-precision and reliable GNSS virtual reference calculation can be achieved when the ionosphere is active, disturbance occurs and the like.

Description

Technical Field

[0001] The present invention relates to the field of Beidou positioning technology, and in particular to a Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay. Background Art

[0002] The core idea of ​​using a virtual reference station (VRS) as a base station is to use the observation data of the reference station to establish an error model in the region to correct the relevant errors, generate a virtual reference station near the mobile station, and then solve the ultra-short baseline formed by the virtual reference station and the mobile station. Therefore, as long as the observation value generated by the virtual reference station is accurate enough, the precise coordinates of the mobile station can be obtained.

[0003] Ionospheric delay is one of the main error sources affecting the positioning of the Global Navigation Satellite System (GNSS). When the satellite is at a low altitude angle, the maximum error can reach 150m. The existing ionospheric correction model can correct up to about 60%. Using dual-frequency observations, 99% of the ionospheric delay error can be corrected while ignoring the influence of high-order ionospheric terms. The ionospheric delay in VRS observations is calculated by the interpolation model, and the correction accuracy of the interpolation model is mainly affected by the activity of the ionosphere. As part of the space environment, the ionosphere is mainly affected by solar activities. Solar activities such as solar flares and corona will cause the ionosphere to be abnormally active. This phenomenon is particularly obvious in low-latitude areas. In low-latitude areas, due to the influence of the fountain effect, the plasma density of the ionosphere produces an uneven structure. When electromagnetic waves pass through this irregular body, it will cause GNSS signal attenuation, resulting in serious cycle slips and loss of lock in the observation values, resulting in reduced accuracy or even failure of the network's high-precision positioning (RTK) service. Since the ionospheric delay has a complex variation law and many influencing factors, the interference of ionospheric delay on the GNSS solution accuracy is more obvious.

[0004] The accuracy of observations in GNSS positioning plays a decisive role in the adjustment results. Satellite altitude angle and signal-to-noise ratio are important indicators that reflect the quality of observations. The random model constructed using these indicators is generally used to weaken the influence of residual atmospheric errors and multipath effects. The traditional VRS weighting method mainly uses the altitude angle model and the signal-to-noise ratio model for weighting. The altitude angle model mainly believes that the atmospheric error level and multipath effect of satellite observations are inversely proportional to the altitude angle. The smaller the altitude angle, the greater the observation error; the signal-to-noise ratio is often used to reflect the quality of signal reception, which is the ratio of signal to noise strength. The signal-to-noise ratio is related to the signal strength of the observation, the multipath effect, the error on the propagation path, etc., and can also reflect the accuracy of the observation to a certain extent.

[0005] During the day, the total electron content of the ionosphere caused by solar radiation changes dramatically, which causes the ionospheric delay error in GNSS positioning to show significant temporal and spatial variation characteristics. When using the above-mentioned traditional altitude angle weighting method, the influence of the time-varying characteristics of the above-mentioned ionospheric error is not taken into account, which leads to a decrease in RTK positioning performance. Especially in the afternoon, the error correction accuracy of the ionosphere is relatively low, resulting in poor terminal positioning accuracy. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the existing technology fails to take into account the influence of the ionosphere when using a virtual reference station to perform network RTK real-time positioning service solution, resulting in reduced positioning performance of the network RTK service terminal, and proposes a Beidou virtual reference high-precision positioning method that takes into account the influence of ionospheric delay.

[0007] On the one hand, the present invention proposes a Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay, which is applied to a server side and includes:

[0008] The server receives and verifies the coordinate information and observation data of the station and the coordinate information and observation data of the CORS station, and selects a CORS station as a primary reference station;

[0009] The server calculates the double difference ionospheric delay of the check station relative to the main reference station based on the received coordinate information and observation data.

[0010] The server side interpolates the double difference ionospheric delay at the construction location of the check station according to the main reference station. The double difference ionospheric delay obtained by interpolation Generate the virtual reference station, and obtain the virtual observation value of the virtual reference station;

[0011] The server end calculates the double difference ionospheric delay of the check station relative to the main reference station And the double difference ionospheric delay at the construction location of the check station Calculate the satellite's ionospheric error;

[0012] The server sends the virtual observation value and the ionospheric error of the satellite to the mobile station end, so that the mobile station end weights the prior accuracy of the virtual observation value, the ionospheric error of the satellite and the altitude angle of the double difference observation value, and performs differential positioning based on the weights to obtain the coordinates of the mobile station end relative to the virtual reference station position benchmark.

[0013] Preferably, the double difference ionospheric delay of the check station relative to the selected CORS station is As a double difference ionospheric delay reference value.

[0014] Preferably, the server side is based on the and stated The ionospheric error of the satellite is calculated. Specifically, the server calculates the absolute value of the double-difference ionospheric delay interpolation residual of the virtual reference station satellite by satellite, which is and is defined as the ionospheric error σ corresponding to the satellite resI .

[0015] In a second aspect, a Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay proposed by the present invention is applied to the mobile station end, comprising:

[0016] The mobile station receives the virtual observation value and the ionospheric error of the satellite sent from the server;

[0017] The mobile station combines the virtual observation value with the ionospheric error σ of the satellite resI The a priori precision σ related to the altitude angle of the double-difference observations ele Carry out weight determination and obtain weight determination information;

[0018] The mobile station performs differential positioning solution in combination with the positioning weight information and the virtual observation value to obtain the coordinates of the mobile station relative to the position benchmark of the virtual reference station.

[0019] Preferably, obtaining the weighting information includes:

[0020] Combining the empirical value and the satellite altitude angle, the non-difference observation value of a single satellite is calculated;

[0021] According to the non-difference observation value, the priori accuracy σ of the height angle of the double-difference observation value is calculated by the error propagation law. ele ;

[0022] The ionospheric error σ for the satellite resI The a priori precision σ associated with the altitude angle of the double difference observation ele A priori error comprehensive weighting is performed to obtain the weighting information.

[0023] In a third aspect, the present invention proposes a Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay, comprising at least one server end and one mobile station end, wherein the server end is connected to the mobile station end, and the method comprises:

[0024] S1. Based on the coordinate information and observation data of the check station and the coordinate information and observation data of the CORS station received by the server, the server selects a CORS station as the main reference station and calculates the double difference ionospheric delay of the check station relative to the main reference station.

[0025] S2. Based on the primary reference station, the server calculates the double difference ionospheric delay at the construction location of the check station The double difference ionospheric delay obtained by interpolation Generate the virtual reference station, and obtain the virtual observation value of the virtual reference station;

[0026] S3. Based on the and stated The server side calculates the ionospheric error σ of the satellite resI , and the virtual observation value and the satellite's ionospheric error σ resI Sending to the mobile station;

[0027] S4, based on the reception at the mobile station, the virtual observation value and the ionospheric error σ of the satellite resI , the priori accuracy σ of the altitude angle of the mobile station combined with the double difference observation value ele , perform weight determination and obtain the weight determination information;

[0028] S5. Based on the positioning weight information, the mobile station performs differential positioning solution in combination with the virtual observation value to obtain the coordinates of the mobile station relative to the position benchmark of the virtual reference station.

[0029] Preferably, before the server receives the coordinate information and observation data of the verification station and the coordinate information and observation data of the CORS station, it is also necessary to set up a physical verification station. The specific implementation process is as follows:

[0030] According to the location information of multiple CORS stations around the area to be measured, the coordinates of the center point are obtained;

[0031] A physical reference station is set as the checking station according to the coordinates of the central point.

[0032] Preferably, the double difference ionospheric delay of the check station relative to the main reference station is calculated in S1 It is also necessary to As a double-difference ionospheric delay reference;

[0033] Preferably, in S2, the double difference power delay at the construction location of the check station needs to be interpolated according to the main reference station. And generate the virtual reference station, obtain the virtual observation value of the virtual reference station; wherein the virtual reference station will be used as a base station, and the reference station observation data will be used to establish an error model in the region to repair the relevant errors, and a virtual reference station will be generated near the mobile station. The virtual reference station and the mobile station will form an ultra-short baseline and perform a solution. Therefore, as long as the observation value generated by the virtual reference station is accurate enough, the precise coordinates of the mobile station can be obtained.

[0034] Preferably, in S3, the ionospheric error σ of the satellite is calculated resI Specifically, the server needs to calculate the absolute value of the double-difference ionospheric delay interpolation residual of the virtual reference station satellite by satellite, that is, Defined as the ionospheric error σ corresponding to the satellite resI .

[0035] Preferably, in S4, the mobile station terminal calculates the ionospheric error σ of the satellite based on the virtual observation value. resI , and the prior accuracy σ of the height angle of the double difference observation ele , perform weight determination, and obtain the weight determination information, specifically including:

[0036] Combining the empirical value and the satellite altitude angle, the non-difference observation value of a single satellite is calculated, and the formula is:

[0037]

[0038] Where: coefficients a and b can be determined based on empirical values, and E represents the satellite altitude angle;

[0039] According to the non-difference observation value, the priori accuracy σ of the height angle of the double-difference observation value is calculated by the error propagation law. ele ;

[0040] The ionospheric error σ for the satellite resI The a priori precision σ associated with the altitude angle of the double difference observation ele The prior error is comprehensively weighted to obtain the weighting information, and the formula is:

[0041]

[0042] Where: w is the weight information, σ resI is the ionospheric error of the satellite, σ ele is the prior accuracy of the altitude angle of the double difference observation.

[0043] Further preferably, the ionospheric error of the satellite is taken into consideration as part of the weighting, which can effectively avoid the problem of reduced accuracy or even failure of network RTK services caused by the uneven structure of the plasma density of the ionosphere due to the influence of solar flares, corona and fountain effects.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a weighting method combining the influence of ionospheric delay, by constructing a physical check station, and calculating the double difference ionospheric delay of the check station relative to the main reference station. The calculation result is used as the double difference ionospheric delay reference value, and the double difference ionospheric delay reference value at the construction location of the check station obtained by interpolation of the virtual reference station is calculated. Will and The absolute value of the difference between the two is used as the ionospheric error of the satellite. Compared with the prior art, the present invention, based on the accuracy of the altitude angle related prior observation value combined with the double difference observation value, can weaken the gross error caused by ionospheric anomaly by combining the ionospheric error of the satellite, and realize high-precision and reliable GNSS virtual benchmark solution when the ionosphere is active and disturbance occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flowchart of a Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0048] Example 1

[0049] The existing technology mainly adopts the altitude angle model and the signal-to-noise ratio model to weight the virtual reference station when realizing the weighting. The altitude angle model mainly considers that the atmospheric error level and multipath effect of satellite observations are inversely proportional to the altitude angle. The smaller the altitude angle, the larger the observation error. The signal-to-noise ratio is often used to reflect the signal reception quality, which is the ratio of signal to noise intensity. The signal-to-noise ratio is related to the signal strength, multipath effect, and error on the propagation path of the observation, and can also reflect the accuracy of the observation to a certain extent. However, ionospheric delay, as one of the main error sources affecting the global navigation satellite system (GNSS) positioning, is often ignored during weighting, resulting in GNSS signal attenuation, causing serious cycle slips and loss of lock in the observation, resulting in reduced accuracy or even failure of network high-precision positioning (RTK) services.

[0050] Based on this, the present embodiment proposes a Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay, including at least one server end and one mobile station end, the server end is connected to the mobile station end, and the method includes:

[0051] S1. Based on the coordinate information and observation data of the check station and the coordinate information and observation data of the CORS station received by the server, the server selects a CORS station as the main reference station and calculates the double difference ionospheric delay of the check station relative to the main reference station.

[0052] S2. Based on the primary reference station, the server calculates the double difference ionospheric delay at the construction location of the check station The double difference ionospheric delay obtained by interpolation Generate the virtual reference station, and obtain the virtual observation value of the virtual reference station;

[0053] S3. Based on the and stated The server side calculates the ionospheric error σ of the satellite resI , and the virtual observation value and the satellite's ionospheric error σ resI Sending to the mobile station;

[0054] S4, based on the reception at the mobile station, the virtual observation value and the ionospheric error σ of the satellite resI , the priori accuracy σ of the altitude angle of the mobile station combined with the double difference observation value ele , perform weight determination and obtain the weight determination information;

[0055] S5. Based on the positioning weight information, the mobile station performs differential positioning solution in combination with the virtual observation value to obtain the coordinates of the mobile station relative to the position benchmark of the virtual reference station.

[0056] Before the server receives the coordinate information and observation data of the verification station and the coordinate information and observation data of the CORS station, it is necessary to set up a physical verification station. The specific implementation process is as follows:

[0057] According to the location information of multiple CORS stations around the area to be measured, the coordinates of the center point are obtained;

[0058] A physical reference station is set as the checking station according to the coordinates of the central point.

[0059] The double difference ionospheric delay of the check station relative to the main reference station is calculated in S1. It is also necessary to As a double-difference ionospheric delay reference;

[0060] Among them, S2 needs to interpolate the double difference power delay at the construction location of the check station according to the main reference station The double difference ionospheric delay obtained by interpolation Generate the virtual reference station and obtain the virtual observation value of the virtual reference station; wherein the virtual reference station will be used as a base station, and the reference station observation data will be used to establish an error model in the region to repair the relevant errors, and a virtual reference station will be generated near the mobile station. The virtual reference station and the mobile station will form an ultra-short baseline and perform the solution. Therefore, as long as the observation value generated by the virtual reference station is accurate enough, the precise coordinates of the mobile station can be obtained.

[0061] Furthermore, the generation process of the virtual reference station includes:

[0062] In a CORS network, first each CORS station receives and sends its observation data to the server;

[0063] The server uses data sent by multiple CORS stations to fix the ambiguity of the baselines in the CORS observation network, and solves the spatial phase errors between baselines, such as the ionosphere and the troposphere, and then establishes a spatial distribution model of spatial correlation errors in combination with the location information of the CORS stations;

[0064] The mobile station obtains its own approximate coordinates through single-point positioning, and sends the approximate coordinates to the server;

[0065] The server uses the approximate coordinates of the mobile station and the spatial distribution model of the spatial correlation error to interpolate and calculate the spatial correlation error of the mobile station, and finally constructs a virtual reference station based on the spatial correlation error obtained by the interpolation.

[0066] Among them, the ionospheric error σ of the satellite is calculated in S3 resI Specifically, the server needs to calculate the absolute value of the double-difference ionospheric delay interpolation residual of the virtual reference station satellite by satellite, that is, Defined as the ionospheric error σ corresponding to the satellite resI .

[0067] Among them, the mobile station end in S4 calculates the ionospheric error σ of the satellite based on the virtual observation value resI , and the prior accuracy σ of the height angle of the double difference observation ele , perform weight determination, and obtain the weight determination information, specifically including:

[0068] Combining the empirical value and the satellite altitude angle, the non-difference observation value of a single satellite is calculated, and the formula is:

[0069]

[0070] Where: coefficients a and b can be determined based on empirical values, and E represents the satellite altitude angle;

[0071] According to the non-difference observation value, the priori accuracy σ of the height angle of the double-difference observation value is calculated by the error propagation law. ele ;

[0072] The ionospheric error σ for the satellite resI The a priori precision σ associated with the altitude angle of the double difference observation ele The prior error is comprehensively weighted to obtain the weighting information, and the formula is:

[0073]

[0074] Where: w is the weight information, σ resI is the ionospheric error of the satellite, σ ele is the prior accuracy of the altitude angle of the double difference observation.

[0075] Among them, considering the ionospheric error of the satellite as a part of the weighting can effectively avoid the problem of reduced accuracy or even failure of network RTK service caused by the uneven structure of the plasma density of the ionosphere due to the influence of solar flares, corona and fountain effects.

[0076] The embodiment proposes a Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay, which is applied to a server side and includes:

[0077] The server receives and verifies the coordinate information and observation data of the station and the coordinate information and observation data of the CORS station, and selects a CORS station as a primary reference station;

[0078] The server calculates the double difference ionospheric delay of the check station relative to the main reference station based on the received coordinate information and observation data.

[0079] The server side interpolates the double difference ionospheric delay at the construction location of the check station according to the main reference station. and generating a virtual reference station, and obtaining a virtual observation value of the virtual reference station;

[0080] The server end calculates the double difference ionospheric delay of the check station relative to the main reference station And the double difference ionospheric delay at the construction location of the check station Calculate the satellite's ionospheric error;

[0081] The server sends the virtual observation value and the ionospheric error of the satellite to the mobile station end, so that the mobile station end weights the prior accuracy of the virtual observation value, the ionospheric error of the satellite and the altitude angle of the double difference observation value, and performs differential positioning based on the weights to obtain the coordinates of the mobile station end relative to the virtual reference station position benchmark.

[0082] The double difference ionospheric delay of the check station relative to the selected CORS station is As a double difference ionospheric delay reference value.

[0083] Wherein, the server end is based on the and stated The ionospheric error of the satellite is calculated. Specifically, the server calculates the absolute value of the double-difference ionospheric delay interpolation residual of the virtual reference station satellite by satellite, which is and is defined as the ionospheric error σ corresponding to the satellite resI .

[0084] The embodiment proposes a Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay, which is applied to the mobile station, and includes:

[0085] The mobile station receives the virtual observation value and the ionospheric error of the satellite sent from the server;

[0086] The mobile station combines the virtual observation value with the ionospheric error σ of the satellite resI The a priori precision σ related to the altitude angle of the double-difference observations ele Carry out weight determination and obtain weight determination information;

[0087] The mobile station performs differential positioning solution in combination with the positioning weight information and the virtual observation value to obtain the coordinates of the mobile station relative to the position benchmark of the virtual reference station.

[0088] Wherein, obtaining the weighting information includes:

[0089] Combining the empirical value and the satellite altitude angle, the non-difference observation value of a single satellite is calculated;

[0090] According to the non-difference observation value, the priori accuracy σ of the height angle of the double-difference observation value is calculated by the error propagation law. ele ;

[0091] The ionospheric error σ for the satellite resI The a priori precision σ associated with the altitude angle of the double difference observation ele A priori error comprehensive weighting is performed to obtain the weighting information.

[0092] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay, characterized in that: Applied to the server side, including: The server receives and verifies the coordinate information and observation data of the station and the coordinate information and observation data of the CORS station, and selects a CORS station as a primary reference station; The server calculates the double difference ionospheric delay of the check station relative to the main reference station based on the received coordinate information and observation data. The server side interpolates the double difference ionospheric delay at the construction location of the check station according to the main reference station. The double difference ionospheric delay obtained by interpolation Generate a virtual reference station, and obtain virtual observation values ​​of the virtual reference station; The server end calculates the double difference ionospheric delay of the check station relative to the main reference station And the double difference ionospheric delay at the construction location of the check station Calculate the satellite's ionospheric error; The server sends the virtual observation value and the ionospheric error of the satellite to the mobile station end, so that the mobile station end weights the prior accuracy of the virtual observation value, the ionospheric error of the satellite and the altitude angle of the double difference observation value, and performs differential positioning based on the weights to obtain the coordinates of the mobile station end relative to the virtual reference station position benchmark.

2. The Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay according to claim 1, characterized in that: The double-difference ionospheric delay of the check station relative to the selected CORS station is As a double difference ionospheric delay reference value.

3. The Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay according to claim 1, characterized in that: The server side according to the and stated The ionospheric error of the satellite is calculated. Specifically, the server calculates the absolute value of the double-difference ionospheric delay interpolation residual of the virtual reference station satellite by satellite, which is and is defined as the ionospheric error σ corresponding to the satellite resI .

4. A Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay, characterized in that: Applied to the mobile station, including: The mobile station receives the virtual observation value and the ionospheric error of the satellite sent from the server; The mobile station combines the virtual observation value with the ionospheric error σ of the satellite resI The a priori precision σ related to the altitude angle of the double-difference observations ele Carry out weight determination and obtain weight determination information; The mobile station performs differential positioning solution in combination with the positioning weight information and the virtual observation value to obtain the coordinates of the mobile station relative to the position benchmark of the virtual reference station.

5. The Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay according to claim 4 is characterized in that: Obtaining the weighting information includes: Combining the empirical value and the satellite altitude angle, the non-difference observation value of a single satellite is calculated; According to the non-difference observation value, the priori accuracy σ of the height angle of the double-difference observation value is calculated by the error propagation law. ele ; The ionospheric error σ for the satellite resI The a priori precision σ associated with the altitude angle of the double difference observation ele A priori error comprehensive weighting is performed to obtain the weighting information.

6. A Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay, characterized in that: The method comprises at least one of the server end and the mobile station end, wherein the server end is connected to the mobile station end, and the method comprises: S1. Based on the coordinate information and observation data of the check station and the coordinate information and observation data of the CORS station received by the server, the server selects a CORS station as the main reference station and calculates the double difference ionospheric delay of the check station relative to the main reference station. ; S2. Based on the primary reference station, the server calculates the double difference ionospheric delay at the construction location of the check station The double difference ionospheric delay obtained by interpolation Generate the virtual reference station, and obtain the virtual observation value of the virtual reference station; S3. Based on the and stated The server side calculates the ionospheric error σ of the satellite resI , and the virtual observation value and the satellite's ionospheric error σ resI Sending to the mobile station; S4, based on the reception at the mobile station, the virtual observation value and the ionospheric error σ of the satellite resI , the priori accuracy σ of the altitude angle of the mobile station combined with the double difference observation value ele , perform weight determination and obtain the weight determination information; S5. Based on the positioning weight information, the mobile station performs differential positioning solution in combination with the virtual observation value to obtain the coordinates of the mobile station relative to the position benchmark of the virtual reference station.

7. The Beidou virtual reference high-precision positioning method taking into account the influence of ionospheric delay according to claim 6 is characterized in that: Before the server receives the coordinate information and observation data of the verification station and the coordinate information and observation data of the CORS station, the method further includes: According to the location information of multiple CORS stations around the area to be measured, the coordinates of the center point are obtained; A physical reference station is set as the checking station according to the coordinates of the central point.

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