CN117348047A - Data processing method for maintaining RTK fixed precision in large differential age - Google Patents

Data processing method for maintaining RTK fixed precision in large differential age Download PDF

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Publication number
CN117348047A
CN117348047A CN202311308469.7A CN202311308469A CN117348047A CN 117348047 A CN117348047 A CN 117348047A CN 202311308469 A CN202311308469 A CN 202311308469A CN 117348047 A CN117348047 A CN 117348047A
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error
value
data processing
linear function
processing method
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Inventor
金蕾
黄策
温小华
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Suzhou Tianshuo Navigation Technology Co ltd
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Suzhou Tianshuo Navigation Technology Co ltd
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Priority to CN202311308469.7A priority Critical patent/CN117348047A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/35—Constructional details or hardware or software details of the signal processing chain
    • G01S19/37—Hardware or software details of the signal processing chain
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/40—Correcting position, velocity or attitude
    • G01S19/41—Differential correction, e.g. DGPS [differential GPS]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position
    • G01S19/43—Determining position using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry

Abstract

The invention discloses a data processing method for keeping RTK fixed precision in large differential age, which comprises the following steps: performing double difference observation by using data of the mobile station and the reference station; judging whether the differential data is normally received or not, and if not, estimating the position change by using the carrier observation value between the mobile station epochs as the difference. According to the invention, based on an actual application scene, under the condition that the instability of differential data is required to be solved, the RTK precision can be maintained under the condition that PPP or inertial navigation technology and elements are not relied on, and the positioning precision of the invention can be maintained well along with the increase of differential age.

Description

Data processing method for maintaining RTK fixed precision in large differential age
Technical Field
The invention relates to a data processing method for keeping RTK fixed precision in large differential age.
Background
The satellite navigation positioning technology has basically replaced the ground-based radio navigation, traditional geodetic and astronomical measurement navigation positioning technology at present, and has promoted the brand new development in the field of geodetic and navigation positioning. Today, GNSS systems are not only national security and economic infrastructure, but are also important markers embodying the status of the modernized nations and the comprehensive national power of the countries. Because of its important significance in politics, economy, military, etc., major military nations and economies of the world are competing to develop independent autonomous satellite navigation systems.
GNSS (Global Navigation Satellite System) the global navigation positioning system comprises a United states GPS, russian GLONASS, galileo in Europe and Beidou in China, and can provide uninterrupted high-precision global covered navigation signal resources for users, so that all-weather real-time positioning, speed measurement and time service functions are realized.
The global positioning system real-time kinematic (RTK) technique requires that the mobile station keep real-time tracking of satellites while receiving the observation data or corrections broadcast by the base station or the CORS service for differential positioning. In an actual application scenario, when the communication condition is limited, the differential data cannot be stably established. In general, as the differential time length is prolonged, the positioning accuracy is reduced more rapidly. Conventional locating cards set the differential zero-period maximum of the RTK at 60 seconds. With the perfect establishment of satellite systems in various countries, more satellites are available for observation, and the broadcasting quantity of differential data is greatly increased. RTCM institutions and GNSS receiver manufacturers are striving to reduce the amount of broadcast data by designing formats with higher compression rates. But such a format design does not solve this problem when the link is unstable. The existing method is to add PPP (precision single point positioning) technology or add inertial navigation elements, but the existing method is an integrated machine, adds cost and cannot be applied to existing equipment in the market.
Disclosure of Invention
The invention aims to overcome the defect that a GNSS receiver in the prior art cannot keep RTK fixed precision in a large differential age, and provides a data processing method for keeping RTK fixed precision in the large differential age, which can be used for keeping RTK precision under the condition that differential data is unstable and does not depend on PPP or inertial navigation technology and elements based on actual application scenes.
The invention solves the technical problems by the following technical scheme:
the data processing method for maintaining the fixed precision of the RTK in the large differential age is characterized by comprising the following steps of:
performing double difference observation by using data of the mobile station and the reference station;
judging whether the differential data is normally received or not, and if not, estimating the position change by using the carrier observation value between the mobile station epochs as the difference.
Preferably, the data processing method includes:
and judging whether the value of the differential delay is larger than a preset value, and if so, estimating the position change by adopting the difference of the carrier observation values among the mobile station epochs.
Preferably, the preset value is obtained through a positioning error obtained by using an RTK method and a positioning error obtained by using a method of carrier observation value difference among epochs.
Preferably, the positioning error obtained by using the RTK method is obtained through satellite position error, satellite clock drift, high-order term error of an ionosphere and troposphere error;
the positioning error obtained by the method of utilizing the carrier observation value difference between the epochs is obtained through observation noise.
Preferably, the satellite position error and the error caused by the satellite clock drift are estimated by using a first linear function, wherein the gradient of the first linear function is in a range of [0.029,0.038], the ionosphere higher-order term error and the troposphere error are estimated by using a second linear function, the second linear function takes the differential delay as a variable, the gradient of the second linear function is a first preset value, and the positioning error obtained by using the RTK method is obtained by using the gradient of the first linear function and the gradient of the second linear function.
Preferably, the formula for obtaining the positioning error obtained by using the RTK method is as follows:
ΔRTK error ＝a*Δt
wherein Δt isDifferential delay value, ΔRTK error For positioning errors obtained by using an RTK method, a is the sum of the slope of a first linear function and the slope of a second linear function, and the smaller the latitude of the place where the measurement is, the larger the slope of the second linear function.
Preferably, the formula for obtaining the positioning error obtained by the method of using the carrier observation value difference between the epochs is as follows:
wherein Δt is the value of differential delay, ΔEDPOS error And b is a second preset value obtained according to observation noise.
Preferably, a value of the same time difference delay as the positioning error obtained by the RTK method and the positioning error obtained by the inter-epoch carrier observation value difference method is obtained as the preset value.
The invention also provides a method for acquiring the preset value of the differential age, which is characterized in that the method is used for acquiring the preset value in the data processing method.
The invention also provides a GNSS receiver which is characterized in that the GNSS receiver is used for realizing the data processing method.
On the basis of conforming to the common knowledge in the field, the above preferred conditions can be arbitrarily combined to obtain the preferred examples of the invention.
The invention has the positive progress effects that:
the invention can utilize the existing component equipment of the current GNSS mapping all-in-one machine to improve the fixing rate and fixing precision of the GNSS RTK and greatly improve the positioning precision.
Drawings
Fig. 1 is a schematic diagram showing the result of observing the data error in embodiment 1 of the present invention.
Fig. 2 is a schematic diagram of the differential age and positioning error coordinates in embodiment 1 of the present invention.
Fig. 3 is a flowchart of a data processing method according to embodiment 1 of the present invention.
Fig. 4 is a flowchart of a method for obtaining a differential age preset value in embodiment 1 of the present invention.
Detailed Description
The invention is further illustrated by means of the following examples, which are not intended to limit the scope of the invention.
Example 1
The present embodiment provides a GNSS receiver for maintaining RTK fixed accuracy at large differential age, the GNSS receiver including a processing module and a receiving module.
The receiving module is used for carrying out double difference observation by utilizing data of the mobile station and the reference station.
The processing module is used for judging whether the differential data is normally received or not, and if not, the position change is estimated by utilizing the carrier observation value difference among the mobile station epochs.
The traditional positioning mode is to perform double-difference observation through the data of the mobile station and the reference station before the differential data are broken.
The formula (1) phi is a single difference observed value of satellites p and q observed by a mobile station r at the current T moment, D is the distance from the satellite to a receiver, V is the satellite clock difference, N is the ambiguity, I is the ionospheric error, and T is the tropospheric error. Equation (2) is a single difference observation value of satellites p, q observed by reference station b before Δt. Subtracting the formula (1) from the formula (2) to obtain a double difference observation value. From the equation, it can be derived that the positioning accuracy of the RTK decreases with the increase of the differential delay, and the influencing factors are mainly satellite position error, ionization layer higher-order term error and satellite clock drift.
Specifically, the processing module is used for:
and judging whether the value of the differential delay is larger than a preset value, and if so, estimating the position change by adopting the difference of the carrier observation values among the mobile station epochs.
The preset value is obtained through a positioning error obtained by an RTK method and a positioning error obtained by a method of carrier observation value difference among epochs.
Specifically, the positioning error obtained by using the RTK method is obtained through satellite position error, satellite clock drift, high-order term error of an ionosphere and troposphere error.
The positioning error obtained by the method of utilizing the carrier observation value difference between the epochs is obtained through observation noise.
Further, the satellite position error and the satellite clock-drift induced error are estimated using a first linear function having a slope ranging from [0.029,0.038].
The ionosphere higher order term errors and troposphere errors are estimated using a second linear function that varies with differential delay.
And the slope of the second linear function is a first preset value, and the positioning error obtained by the RTK method is obtained by utilizing the slope of the first linear function and the slope of the second linear function.
Knowing the velocity of the satellite's motion, the satellite's distance from the receiver, the accuracy of the broadcast ephemeris.
In addition, satellite clock drift is also responsible for error accumulation. The effect of satellite position error and satellite clock drift can be estimated as a linear function with a slope of about 0.029,0.038 with the slope of the first linear function taking a value of 0.038 in this embodiment as the differential delay increases.
Second, the higher order term errors of the ionosphere cannot be ignored as the differential delay increases.
The literature has shown that the higher order terms of the ionisation layer have an effect on both orbit and observations.
The magnitude of its effect is related to the latitude position of the survey station and cannot be eliminated by the inter-station difference. Also to be taken into account is tropospheric error.
The error of these two terms can also be expressed as a linear function with differential delay as a variable, with the slope empirical value of this embodiment taking the value of 0.051. For low latitude areas, the experience value will increase as the ionospheric variability is greater.
Specifically, the formula for obtaining the positioning error obtained by using the RTK method is as follows:
ΔRTK error ＝a*Δt
wherein Δt is the value of the differential delay, ΔRTK error In order to obtain a positioning error by using the RTK method, a is the sum of the slope of the first linear function and the slope of the second linear function, in this embodiment, the value of a is 0.089, and the smaller the latitude of the place where the measurement is, the larger the slope of the second linear function.
The estimation of the position change is performed if the inter-mobile epoch carrier observations are made worse.
Equation (4) is the observed value of satellite p observed by the rover at the current time t. D is the distance from the satellite to the receiver, V is the satellite clock difference, N is the ambiguity, I is the ionospheric error, and T is the tropospheric error. Subtracting the formula (4) from the formula (5) to obtain an inter-epoch single difference observation value of the mobile station.
Since the rover keeps continuously tracking the satellite, it is not affected by satellite position error accumulation and satellite clock drift.
The change of the ionosphere with time at the same station can be estimated by double frequency observations. The error in this calculation mode is mainly due to observation noise.
According to the characteristics of noise, the influence of the method on RTK precision can be considered to be along withThe time of flight can be increasedA power function.
That is, the formula for obtaining the positioning error obtained by the method of using the inter-epoch carrier observed value difference is:
wherein Δt is the value of the differential delay in seconds. Delta EDPOS error The unit of the positioning error is centimeter, which is obtained by using the method of carrier observation value difference between epochs. b is a second preset value obtained according to the observed noise. In this embodiment, the value of the second preset value is 0.5.
And acquiring a numerical value of the same time difference delay of the positioning error obtained by using the RTK method and the positioning error obtained by using the inter-epoch carrier observation value difference method as the preset value.
Referring to FIG. 1, the results of our observed data errors at intervals 1s,10s,30s and 60s are shown in FIG. 1, which also demonstrates the accuracy of the formula. For static data, the position change value for each direction should be 0.
The upper left plot in FIG. 1 shows a 3D error of 1 second when the differential zero period is 1 second
When the differential data is 10 seconds, the upper right-hand graph in FIG. 1 shows a 3D error ofThe same approach can be used to achieve 3D errors of 3.1cm and 4.5cm when the differential data is 30 seconds and 60 seconds, respectively.
Referring to fig. 2, the two models of the formula (1) and the formula (2) are compared, the horizontal axis is the differential age (unit: seconds), the vertical axis is the RTK positioning error (unit: cm), and as shown in fig. 2, the first line segment is used to represent the positioning error 301 of the double difference observation by the reference station data before the mobile station and the differential data are disconnected, and the second line segment is used to represent the positioning error 302 obtained by the inter-epoch carrier observation value difference method. It is considered that the positioning accuracy can be well maintained by adopting the carrier phase epoch difference method after the difference age exceeds about 30 seconds.
Referring to fig. 3, with the GNSS receiver described above, this embodiment further provides a data processing method, including:
step 100, performing double difference observation by using data of the mobile station and the reference station;
step 101, judging whether the differential data is received normally, if not, estimating the position change by using the carrier observation value difference between the mobile station epochs.
The step 101 specifically comprises the following steps:
step 1011, determining whether the value of the differential delay is greater than a preset value, if yes, executing step 1012, otherwise, executing step 100 again.
Step 1012, estimating the position change by using the difference between the inter-epoch carrier observations.
The preset value is obtained through a positioning error obtained by an RTK method and a positioning error obtained by a method of carrier observation value difference among epochs.
Specifically, the positioning error obtained by using the RTK method is obtained through satellite position error, satellite clock drift, high-order term error of an ionosphere and troposphere error;
the positioning error obtained by the method of utilizing the carrier observation value difference between the epochs is obtained through observation noise.
The method comprises the steps of estimating satellite position errors and errors caused by satellite clock drift by using a first linear function, wherein the gradient value range of the first linear function is [0.029,0.038], estimating the high-order term errors and troposphere errors of an ionosphere by using a second linear function, wherein the second linear function takes differential delay as a variable, the gradient of the second linear function is a first preset value, and acquiring the positioning errors obtained by using an RTK method by using the gradient of the first linear function and the gradient of the second linear function.
Specifically, the formula for obtaining the positioning error obtained by using the RTK method is as follows:
ΔRTK error ＝a*Δt
wherein Δt is the value of the differential delay, ΔRTK error For positioning errors obtained by using an RTK method, a is the sum of the slope of a first linear function and the slope of a second linear function, and the smaller the latitude of the place where the measurement is, the larger the slope of the second linear function.
Specifically, the formula for obtaining the positioning error obtained by the method of using the inter-epoch carrier observed value difference is:
wherein Δt is the value of differential delay, ΔEDPOS error And b is a second preset value obtained according to observation noise.
Specifically, a value of the same time difference delay of the positioning error obtained by using the RTK method and the positioning error obtained by using the inter-epoch carrier observation value difference method is obtained as the preset value.
Referring to fig. 4, the embodiment further provides a method for acquiring the preset value of the differential age, where the method includes:
step 200, positioning errors obtained by using an RTK method and positioning errors obtained by using a method of observing value differences by using carriers among epochs.
Step 201, obtaining the preset value of the differential age through the positioning error obtained by the RTK method and the positioning error obtained by the inter-epoch carrier observation value differential method.
In step 200, the positioning error obtained by the RTK method is obtained through satellite position error, satellite clock drift, ionosphere higher-order term error and troposphere error;
specifically, the satellite position error and the error caused by satellite clock drift are estimated by using a first linear function, the gradient of the first linear function is in a range of [0.029,0.038], the high-order term error and the troposphere error of the ionosphere are estimated by using a second linear function, the second linear function takes differential delay as a variable, the gradient of the second linear function is a first preset value, and the positioning error obtained by using the RTK method is obtained by using the gradient of the first linear function and the gradient of the second linear function.
The formula for obtaining the positioning error obtained by using the RTK method is as follows:
ΔRTK error ＝a*Δt
wherein Δt is the value of the differential delay, ΔRTK error For positioning errors obtained by using an RTK method, a is the sum of the slope of a first linear function and the slope of a second linear function, and the smaller the latitude of the place where the measurement is, the larger the slope of the second linear function.
In step 200, the positioning error obtained by the method of using inter-epoch carrier observation value difference is obtained through observation noise.
The formula for obtaining the positioning error by using the inter-epoch carrier observation value difference method is as follows:
wherein Δt is the value of differential delay, ΔEDPOS error And b is a second preset value obtained according to observation noise.
Step 201 specifically comprises:
and acquiring a numerical value of the same time difference delay of the positioning error obtained by using the RTK method and the positioning error obtained by using the inter-epoch carrier observation value difference method as the preset value.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that these are by way of example only, and the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the principles and spirit of the invention, but such changes and modifications fall within the scope of the invention.

Claims (10)

1. A data processing method for maintaining fixed precision of an RTK at large differential age, the data processing method comprising:
performing double difference observation by using data of the mobile station and the reference station;
judging whether the differential data is normally received or not, and if not, estimating the position change by using the carrier observation value between the mobile station epochs as the difference.
2. The data processing method according to claim 1, wherein the data processing method comprises:
and judging whether the value of the differential delay is larger than a preset value, and if so, estimating the position change by adopting the difference of the carrier observation values among the mobile station epochs.
3. The data processing method according to claim 2, wherein the preset value is obtained by a positioning error obtained by an RTK method and a positioning error obtained by a method of inter-epoch carrier observation value difference.
4. A data processing method according to claim 3, wherein the positioning error obtained by the RTK method is obtained by satellite position error, satellite clock drift, ionosphere higher order term error and troposphere error;
the positioning error obtained by the method of utilizing the carrier observation value difference between the epochs is obtained through observation noise.
5. The data processing method of claim 4, wherein the satellite position error and the satellite clock-drift induced error are estimated using a first linear function, the slope of the first linear function having a range of [0.029,0.038], the ionospheric higher order term error and the tropospheric error are estimated using a second linear function, the second linear function having a differential delay as a variable, the slope of the second linear function having a first predetermined value, the positioning error obtained using the RTK method being obtained using the slope of the first linear function and the slope of the second linear function.
6. The data processing method of claim 4, wherein the equation for obtaining the positioning error using the RTK method is:
ΔRTK error ＝a*Δt
wherein Δt is the value of the differential delay, ΔRTK error For positioning errors obtained by using an RTK method, a is the sum of the slope of a first linear function and the slope of a second linear function, and the smaller the latitude of the place where the measurement is, the larger the slope of the second linear function.
7. The data processing method of claim 6, wherein the formula for obtaining the positioning error by using the inter-epoch carrier observed value difference is:
wherein Δt is the value of differential delay, ΔEDPOS error And b is a second preset value obtained according to observation noise.
8. The data processing method according to claim 7, wherein a value of a same time difference delay as a positioning error obtained by an RTK method and a positioning error obtained by a method of inter-epoch carrier observation value difference is obtained as the preset value.
9. A method of acquiring a differential age preset value, characterized in that the method is used for acquiring the preset value in the data processing method according to any one of claims 2 to 8.
10. A GNSS receiver for implementing the data processing method according to any of the claims 1 to 8.
CN202311308469.7A 2023-10-11 2023-10-11 Data processing method for maintaining RTK fixed precision in large differential age Pending CN117348047A (en)

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