CN118348564A - Single Beidou and pseudolite combined positioning method in complex environment - Google Patents
Single Beidou and pseudolite combined positioning method in complex environment Download PDFInfo
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Classifications
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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
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/25—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS
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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
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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
- G01S19/38—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
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Abstract
The invention relates to a single Beidou and pseudolite combined positioning method in a complex environment, which comprises the following steps: arranging pseudolites; time synchronization; RTK data processing; analyzing precision; and outputting a result. The time synchronization comprises a time taming algorithm and a time synchronization correction algorithm, so that the time synchronization is guaranteed from two aspects of hardware and algorithm to meet the high-precision positioning requirement, and the problems that a ground pseudolite transmitter adopts an inexpensive crystal oscillator as a time reference and clock synchronization exists between a pseudolite and a real satellite system are solved; the accuracy analysis analyzes from two aspects of positioning accuracy and DOP value, finds out the problem and solves the problem, and ensures smooth output of the high-accuracy positioning result by combining the pseudolite with the single Beidou. The Beidou single-system multi-frequency point is fully utilized to combine with the pseudolite self-defined frequency point to perform real-time detection, so that the space geometric configuration of the satellite in the severe environment is optimized, and the high-precision output of the positioning result is ensured.
Description
Technical Field
The invention relates to the field of surveying and mapping science and technology, in particular to a single Beidou and pseudolite combined positioning method in a complex environment.
Background
With the development of technology, GNSS is applied to aspects of our lives, but is affected by factors such as the number of satellites and shielding, and the application performance of GNSS is greatly reduced in environments with serious and complex shielding areas such as tunnels and valleys. Therefore, a pseudolite technology is developed, so far, the pseudolite technology has been preliminarily applied, and for the fields of high-precision deformation monitoring and positioning and the like, the pseudolite has a temporary lack of formed application cases.
In the field of deformation monitoring, the RTK technology is widely applied at present, a millimeter-level high-precision positioning result can be solved by using GNSS multimode multi-frequency signals, however, considering that foreign navigation systems such as GPS and the like possibly have adverse effects on us at key time points, compared with other systems, the Beidou satellite navigation system which is self-researched in China is higher in precision and better in stability and wider in coverage, so that the monitoring of important infrastructures such as dams and the like is realized, and the high-precision positioning by using single Beidou is also a safer choice. However, in a complex environment, the method can also face the influence of small number of visible satellites and poor space geometry of the satellites, so that the influence can be eliminated to a great extent by introducing pseudolites, and high-quality output of positioning results in the complex environment is ensured. However, in the practical application process, the following problems still exist:
for terrestrial pseudolite transmitters, inexpensive crystal oscillators are commonly used as time references due to cost constraints, so that clock synchronization problems exist between pseudolites and real satellite systems,
And secondly, after the pseudolite and Beidou combined data processing is carried out, the reliability of the pseudolite cannot be verified, and the accuracy of an output result is influenced under the influence of multipath errors of the pseudolite and or positioning errors in navigation positioning.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a single Beidou and pseudolite combined positioning method in a complex environment so as to solve one or more problems in the prior art.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
A single Beidou and pseudolite combined positioning method in a complex environment comprises the following steps:
arranging pseudolites;
time synchronization;
RTK data processing;
analyzing precision;
And outputting a result.
Further, the pseudolite layout comprises navigation message format determination, self-position acquisition and pseudolite frequency determination.
Further, the time synchronization includes the steps of:
time tame;
a time synchronization correction algorithm;
and (3) judging the time deviation, if the time deviation delta T of the pseudolite and the real satellite is not larger than a given threshold value, carrying out the next RTK data processing, and if the time deviation delta T is larger than the given threshold value, returning to time discipline.
Further, the time-taming includes taming the crystal oscillator, the taming the crystal oscillator including the steps of:
measuring the phase difference between the local frequency standard and the reference signal;
converting the phase difference into a voltage value or a digital signal;
performing voltage control adjustment or digital adjustment on the crystal oscillator;
And keeping the output frequency and the frequency of the reference signal synchronous, and finishing the taming.
Further, the calculation formula of the time synchronization correction algorithm is as follows:
in the method, in the process of the invention, As the clock difference between the satellite and the real satellite,Pseudo-range measurements obtained for pseudolites observing real satellites,Pseudo-range errors such as ionosphere propagation delay errors when the pseudolite observes a real satellite are considered, ρ is a true range value of the pseudolite and the real satellite, x PL,yPL,zPL is a three-dimensional position coordinate of the pseudolite, and x s,ys,zs is a three-dimensional position coordinate of the real satellite.
Further, the RTK data processing includes the steps of:
Establishing a single Beidou and pseudolite observation equation;
Establishing a single Beidou and pseudolite observation equation in high-precision positioning;
RTK positioning and resolving.
Further, the single Beidou observation equation is shown as follows:
in the above-mentioned method, the step of, The pseudo-range observation value of the ith Beidou satellite is represented, r i represents the linear distance between the satellite and a receiver, c represents the light speed, deltat u represents the receiver clock difference, deltat BDS represents the Beidou satellite clock difference, epsilon j represents the measurement noise of the satellite, and T i and I i respectively represent the tropospheric error and the ionospheric error of the Beidou satellite;
The pseudolite observation equation is shown as follows:
in the above-mentioned method, the step of, The pseudo-range observation value of the j-th pseudolite is represented, r j represents the linear distance between the satellite and the receiver, c represents the light speed, delta T u represents the receiver clock difference, delta T PL is the pseudolite clock difference, epsilon i respectively represents the measurement noise of the satellite, T j represents the tropospheric error of the Beidou satellite, and delta j is the pseudolite multipath error;
the single Beidou observation equation in high-precision positioning is shown as follows:
in the above formula, λ represents a wavelength, and N is a whole-cycle ambiguity.
The pseudolite observation equation in high-precision positioning is shown as follows:
in the above formula, λ represents a wavelength, and N is a whole-cycle ambiguity.
Further, the precision analysis includes the steps of:
Analyzing the positioning accuracy, returning to RTK data processing if the Beidou pseudo satellite combined positioning result is greater than or equal to the single Beidou positioning result or the fluctuation amplitude of the Beidou pseudo satellite combined positioning result in a time sequence is greater than the single Beidou positioning result after calculation through an accuracy formula, and outputting the result if the result is consistent with the single Beidou positioning result;
And (3) checking the DOP value, returning to the pseudolite layout if the DOP value of the Beidou pseudolite combined positioning is larger than or equal to the DOP value of the single Beidou positioning after calculation through the DOP value formula, and outputting a result if the DOP value is matched with the DOP value.
Further, the precision formula is as follows:
In the above formula, x i is an observed value, For the observation average value, n is the number of observations.
Further, the DOP value formula is as follows:
In the above formula, GDOP is a geometric precision factor, PDOP is a position precision factor, HDOP is a horizontal precision factor, VDOP is an elevation precision factor, and Q 11、q22、q33、q44 is an element in the weight coefficient array Q.
Compared with the prior art, the invention has the following beneficial technical effects:
Firstly, by introducing a time tame crystal oscillator and using a time synchronization algorithm, the problems that a ground pseudolite transmitter adopts an inexpensive crystal oscillator as a time reference and clock synchronization exists between a pseudolite and a real satellite system are solved, and the time synchronization is ensured from two aspects of hardware and algorithm so as to achieve the high-precision positioning requirement.
And secondly, verifying the reliability of the pseudolite after RTK data processing, analyzing from two aspects of positioning accuracy and DOP value, finding out and solving the problem, and ensuring the smooth output of the high-accuracy positioning result of the pseudolite combined with single Beidou.
Drawings
Fig. 1 shows a flow chart of a single Beidou and pseudolite combined positioning method in a complex environment according to an embodiment of the invention.
Detailed Description
In order to make the purposes, technical schemes and advantages of the invention more clear, the invention provides a single Beidou and pseudolite combined positioning method under a complex environment by combining the drawings and the specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for the purpose of facilitating and clearly aiding in the description of embodiments of the invention. For a better understanding of the invention with objects, features and advantages, refer to the drawings. It should be understood that the structures, proportions, sizes, etc. shown in the drawings are for illustration purposes only and should not be construed as limiting the invention to the extent that any modifications, changes in the proportions, or adjustments of the sizes of structures, proportions, or otherwise, used in the practice of the invention, are included in the spirit and scope of the invention which is otherwise, without departing from the spirit or essential characteristics thereof.
Step 1: pseudolite layout referring to fig. 1, the pseudolite layout includes navigation message format determination, self-location acquisition and pseudolite frequency determination.
When signal interference is generated by other foreign satellite navigation systems such as GPS, the frequency points B1C/L1/E1, B2a/L5/E5a and B2B/G3/E5B are completely overlapped, namely, the signal B1C is impossible to be received only and the signal L1/E1 is impossible to be received, so that for single Beidou positioning, in order to avoid signal interference of other systems, the special frequency points B1I and B3I can be used as far as possible. Similarly, the frequency selection of pseudolites should also take into account signal interference issues while also reducing regulatory risks.
The user receiver obtains a data code of 50bps by carrying out carrier demodulation and pseudo code spread spectrum demodulation on the received satellite signals, and then can finally compile the data code into a navigation message according to the format of the navigation message. The navigation message contains important information for positioning such as time, satellite orbit, ionosphere delay and the like. The satellite arranges the navigation messages into a data stream in the form of a frame and subframe structure. Each satellite transmits navigation messages frame by frame, and the satellites proceed in a sub-frame by sub-frame manner when transmitting each frame of messages. Each frame of navigation message is 1500 bits long and 30s, and sequentially consists of 5 subframes. The first three subframes of the conventional satellite comprise satellite orbit parameters, time, various corrections and the like, and the second two subframes comprise data information such as almanac parameters, ionospheric delay correction parameters, satellite health conditions and the like of the satellite.
The pseudolite can simulate a real satellite, namely, the acquired ephemeris data is utilized to simulate a low-altitude interval satellite signal which cannot be directly received due to the influence of factors such as environment and the like, and the orbit parameters of the pseudolite are similar to those of the real satellite; the position of the non-existent satellite, namely the pseudolite, can be simulated to be stable and unchanged, the transmitted signal is a static signal, and the position of the monitoring station is solved through the known position of the pseudolite. In order to facilitate the calculation, the visible pseudolite is a static satellite, the precise position of the visible pseudolite is only needed to be known at the moment, and orbit information of various satellites is not needed to be provided, in this case, in order to facilitate the demodulation of a user receiver, the message design can be realized by adopting a real satellite navigation message, namely the message rate can be designed to be 50bps, 300 bits are broadcasted every 6 seconds to be 1 subframe, 5 subframes are counted, and the application expansibility is considered, so that the coordinates and the system time delay of the pseudolite are broadcasted through the 4 th subframe, and other subframes are reserved.
For pseudolite positioning, it is important to acquire accurate coordinates of the position of the pseudolite positioning, so the position of the pseudolite positioning should be calibrated in advance before the pseudolite is arranged, and in order to prevent systematic coarse difference caused by position deviation of the pseudolite station during operation, a high-precision positioning module can be arranged on the pseudolite station. The pseudolites and receiver locations should remain as clear as possible, avoiding reflectors. Meanwhile, a specially designed pseudo satellite transmitting antenna, such as a spiral antenna, a microstrip antenna and the like, can be adopted, and the propagation angle of signals of the pseudo satellite transmitting antenna can be standardized by controlling the spiral length of the antenna.
Step 2: with continued reference to fig. 1, further, it is known that the time between satellites must be synchronized according to the principle of navigation positioning, otherwise a time synchronization error is introduced in positioning. Likewise, pseudolites should not only be time synchronized with each other but also need to remain synchronized with system time.
Step 2.1: in time discipline and in combination with BDS time in Beidou, for a ground pseudolite transmitter, low-cost crystal oscillators are generally used as time references due to cost limitation, so that the problem of clock synchronization between a pseudolite and a real satellite system exists. For high-precision positioning, a high-precision time service module is needed, the module can receive clock information of a real satellite, then provide pps second signals to a disciplinary crystal oscillator in the pseudolite, the disciplinary crystal oscillator refers to the pps second signals, meanwhile, based on an internal constant-temperature crystal oscillator, calculate and output more accurate pps second signals and clock signals, and therefore the effect of keeping synchronization of the pseudolite and the real satellite system time is achieved.
The working mode of the tame crystal oscillator can be roughly divided into the following steps:
phase discrimination: firstly, the tame system can perform phase discrimination on an input local frequency standard and a reference signal, and the phase difference of the two signals is measured through high-precision time interval measurement.
Conversion: the phase difference is converted into a voltage value or a digital signal, which represents the deviation between the crystal oscillator output frequency and the reference signal frequency.
And (3) adjusting: the crystal oscillator is subjected to voltage control adjustment or digital adjustment through an adjusting end of the crystal oscillator, so that the output frequency of the crystal oscillator is close to the frequency of the reference signal.
Locking: and the output frequency of the crystal oscillator is kept synchronous with the frequency of the reference signal through a control circuit such as a phase-locked loop and the like, so that the taming process is completed.
In the whole tame process, the tame unit can adjust the output frequency of the crystal oscillator in real time according to the degree of the actual frequency deviating from the nominal value, which is a dynamic process of closed-loop feedback adjustment. In this way, the tamed crystal oscillator can remarkably improve the time measurement precision and the time keeping stability of the system.
Step 2.2: the time synchronization correction algorithm is that the above process is time synchronization of the hardware process, and the hardware itself has a time delay, so in order to ensure more accurate time synchronization, the time synchronization correction algorithm is now used as shown in the following formula 1:
in the method, in the process of the invention, As the clock difference between the satellite and the real satellite,Pseudo-range measurements obtained for pseudolites observing real satellites,Pseudo-range errors such as ionosphere propagation delay errors when the pseudolite observes a real satellite are considered, ρ is a true range value of the pseudolite and the real satellite, x PL,yPL,zPL is a three-dimensional position coordinate of the pseudolite, and x s,ys,zs is a three-dimensional position coordinate of the real satellite.
Because the position erected by the pseudolite can be calibrated in advance, namely the position of the pseudolite is accurately known, the pseudolite built-in high-precision time service module can receive real satellite signals, and the real satellite signals can be calculated by utilizing the method only by observing one real satelliteWhen signals of a plurality of satellites are received, the position change of the pseudo satellite station can be monitored in real time, and the clock error is solved
Step 2.3: according to actual use, the time synchronization accuracy of the time synchronization method can reach nanosecond level, and for different applications, the required time synchronization accuracy, namely the time deviation delta T of the pseudolite and the real satellite, can be different, and normally 20 nanoseconds can meet most application requirements. If the delta T cannot meet the application requirement, namely is larger than a given threshold, returning to time taming, firstly considering the hardware problem, analyzing the performance of the selected high-precision time service module, researching whether the performance of the selected high-precision time service module can meet the required application requirement, and if the performance of the selected high-precision time service module is not larger than the given threshold, entering the next RTK data processing.
Step 3: the RTK data processing, in combination with the beidou data BDS data, please continue to refer to fig. 1, further, after solving the time synchronization problem, can utilize the simultaneous observation equation of the pseudolite and the single beidou observation data, because the observation equation of the pseudolite and the BDS combined positioning is slightly different due to the difference of the propagation paths of the pseudolite and the BDS signals:
step 3.1, the single Beidou observation equation is shown in the following formula 2:
in the above-mentioned method, the step of, The pseudo-range observation value of the ith Beidou satellite is represented, r i represents the linear distance between the satellite and a receiver, c represents the light speed, deltat u represents the receiver clock difference, deltat BDS represents the Beidou satellite clock difference, epsilon j represents the measurement noise of the satellite, and T i and I i respectively represent the tropospheric error and the ionospheric error of the Beidou satellite.
The pseudolite observation equation is shown as follows in figure 3:
in the above-mentioned method, the step of, The pseudo-range observation value of the j-th pseudolite is represented, r j represents the linear distance between the satellite and the receiver, c represents the light speed, Δt u represents the receiver clock difference, Δt PL is the pseudolite clock difference, ε i represents the measured noise of the satellite, T j represents the tropospheric error of the Beidou satellite, and δ j is the pseudolite multipath error.
Because the pseudolite and the GNSS signal have different propagation paths, the propagation paths of the pseudolite signals do not pass through the ionosphere, so that the observation equation of the pseudolite has no ionosphere error. In addition, since the multipath interference signal from the pseudolite is much stronger than the multipath interference signal from the real satellite, the multipath error δ j is introduced separately in the observation equation of the pseudolite.
Step 3.2, in high-precision positioning, carrier phase is mainly used, and a single Beidou observation equation in the high-precision positioning is shown in the following formula 4:
in the above formula, λ represents a wavelength, and N is a whole-cycle ambiguity.
The pseudolite observation equation in the high-precision positioning is shown in the following formula 5:
in the above formula, λ represents a wavelength, and N is a whole-cycle ambiguity.
The accurate determination of the integer ambiguity directly determines the accuracy of the positioning. After the simultaneous observation equations are completed, each unknown quantity is accurately solved, deformation monitoring is carried out on a dam and the like, and an RTK positioning algorithm is mainly applied.
Step 4: with reference to fig. 1, further, after the data processing is completed, in order to verify that the addition of the pseudolite is optimal for the accuracy and geometric spatial configuration of the whole deformation monitoring system, the reliability analysis needs to be performed on the solution result.
And 4.1, analyzing the positioning accuracy, wherein the positioning accuracy can intuitively reflect the effect condition of the Beidou pseudolite combined positioning, and in a complex environment, positioning instability can be possibly caused by only depending on double frequencies of the Beidou B1I and the Beidou B3I, and larger fluctuation exists, so that larger positioning errors are considered. When RTK data processing is carried out, single Beidou positioning and Beidou pseudolite combined positioning can be respectively solved, the difference of the two groups of solutions is compared, and after the pseudolites are introduced in a complex shielding serious environment, the positioning result tends to be stable due to the increase of the number of the satellites and the improvement of the geometric configuration of the satellites.
The precision formula is shown in the following formula 6:
In the above formula, x i is an observed value, For the observation average value, n is the number of observations.
If the precision formula is adopted to calculate, the Beidou pseudo satellite combined positioning result is greater than or equal to the single Beidou positioning result or the fluctuation amplitude of the Beidou pseudo satellite combined positioning result in the time sequence is greater than the single Beidou positioning result, the fact that the pseudo satellite multipath errors are not accurately eliminated during RTK data processing is considered, RTK data processing is returned, and if the precision formula is matched, the output result is waited.
The multipath interference signal of the pseudolite is much stronger than that of a real satellite, the quality of the positioning result of the pseudolite is directly determined by the quality of multipath error elimination, and when the pseudolite and the user equipment are in a static environment, the multipath interference can be approximately understood as constant deviation and can be estimated in advance by constructing a related multipath error elimination model.
Step 4.2, DOP value test. In navigational positioning, the positioning error can ultimately be expressed as the product of the ranging error and the DOP value, where the DOP value represents the composite effect of the satellite/user's relative geometry on the positioning error, the smaller the value, the higher the accuracy for assessing the positioning accuracy of the positioning system and the integrity of the system. In satellite navigation, the receiver position and time error can be represented by the following equations 7 to 9:
ΔX＝(GTG)-1GT·Δρ#(7)
wherein:
In the middle of The directional cosine of the ith satellite.
And Δx= (G TG)-1GT ·Δρ availability weight coefficient array Q, as shown in the following equation 10:
Element q ij is a basis for evaluating satellite positioning results, and the precision factor DOP thereof can be represented by the following formulas 11 to 14:
In the above formula, GDOP is a geometric precision factor, PDOP is a position precision factor, HDOP is a horizontal precision factor, VDOP is an elevation precision factor, and Q 11、q22、q33、q44 is an element in the weight coefficient array Q.
In a complex environment, the geometry of the satellite can be obviously improved by introducing the pseudolite in a low-altitude interval, wherein the improvement of the VDOP value is most obvious, and DOP values of single Beidou positioning and Beidou pseudolite combined positioning can be respectively calculated for checking the improvement condition of the precision of the pseudolite after the pseudolite is introduced.
If the DOP value of the Beidou pseudo satellite combined positioning is larger than or equal to the DOP value of the single Beidou positioning after calculation through the DOP value formula, returning to pseudo satellite layout, considering whether a problem exists in the pseudo satellite layout selection point, and if the problem exists, waiting for an output result.
Step 5: and outputting a result when the positioning accuracy analysis and DOP value inspection are consistent.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. The single Beidou and pseudolite combined positioning method in a complex environment is characterized by comprising the following steps of:
arranging pseudolites;
time synchronization;
RTK data processing;
analyzing precision;
And outputting a result.
2. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 1, wherein the method comprises the following steps: the pseudolite layout comprises navigation message format determination, self-position acquisition and pseudolite frequency determination.
3. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 1, wherein the method comprises the following steps: the time synchronization includes the steps of:
time tame;
a time synchronization correction algorithm;
and (3) judging the time deviation, if the time deviation delta T of the pseudolite and the real satellite is not larger than a given threshold value, carrying out the next RTK data processing, and if the time deviation delta T is larger than the given threshold value, returning to time discipline.
4. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 3, wherein the method comprises the following steps of: the time tame comprises tame crystal oscillator, and the tame crystal oscillator comprises the following steps:
measuring the phase difference between the local frequency standard and the reference signal;
converting the phase difference into a voltage value or a digital signal;
performing voltage control adjustment or digital adjustment on the crystal oscillator;
And keeping the output frequency and the frequency of the reference signal synchronous, and finishing the taming.
5. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 3, wherein the method comprises the following steps of: the calculation formula of the time synchronization correction algorithm is shown as follows:
in the method, in the process of the invention, Clock difference between the satellite and the real satellite; pseudo-range measurement values obtained by observing real satellites for pseudo-satellites; Pseudo-range errors such as ionosphere propagation delay errors when a true satellite is observed for a pseudo-satellite; ρ is the true value of the distance between the pseudolite and the real satellite; (x PL,yPL,zPL) is pseudolite three-dimensional position coordinates and (x s,ys,zs) is true satellite three-dimensional position coordinates.
6. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 1, wherein the method comprises the following steps: the RTK data processing comprises the following steps:
Establishing a single Beidou and pseudolite observation equation;
Establishing a single Beidou and pseudolite observation equation in high-precision positioning;
RTK positioning and resolving.
7. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 6, wherein the method comprises the following steps: the single Beidou observation equation is shown as follows:
in the above-mentioned method, the step of, The pseudo-range observation value of the ith Beidou satellite is represented, r i represents the linear distance between the satellite and a receiver, c represents the light speed, deltat u represents the receiver clock difference, deltat BDS represents the Beidou satellite clock difference, epsilon j represents the measurement noise of the satellite, and T i and I i respectively represent the tropospheric error and the ionospheric error of the Beidou satellite; the pseudolite observation equation is shown as follows:
in the above-mentioned method, the step of, The pseudo-range observation value of the j-th pseudolite is represented, r j represents the linear distance between the satellite and the receiver, c represents the light speed, delta T u represents the receiver clock difference, delta T PL is the pseudolite clock difference, epsilon i respectively represents the measurement noise of the satellite, T j represents the tropospheric error of the Beidou satellite, and delta j is the pseudolite multipath error;
the single Beidou observation equation in high-precision positioning is shown as follows:
In the above formula, lambda represents wavelength, and N is integer ambiguity;
the pseudolite observation equation in high-precision positioning is shown as follows:
in the above formula, λ represents a wavelength, and N is a whole-cycle ambiguity.
8. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 1, wherein the method comprises the following steps: the precision analysis comprises the following steps:
Analyzing the positioning accuracy, returning to RTK data processing if the Beidou pseudo satellite combined positioning result is greater than or equal to the single Beidou positioning result or the fluctuation amplitude of the Beidou pseudo satellite combined positioning result in a time sequence is greater than the single Beidou positioning result after calculation through an accuracy formula, and outputting the result if the result is consistent with the single Beidou positioning result;
And (3) checking the DOP value, returning to the pseudolite layout if the DOP value of the Beidou pseudolite combined positioning is larger than or equal to the DOP value of the single Beidou positioning after calculation through the DOP value formula, and outputting a result if the DOP value is matched with the DOP value.
9. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 8, wherein the method is characterized by comprising the following steps: the precision formula is shown as follows:
In the above formula, x i is an observed value, For the observation average value, n is the number of observations.
10. The method for combining and positioning single Beidou and pseudolites in a complex environment as claimed in claim 8, wherein the method is characterized by comprising the following steps: the DOP value formula is shown as follows:
in the above formula, GDOP is a geometric precision factor, PDOP is a position precision factor, HDOP is a horizontal precision factor, VDOP is an elevation precision factor, and Q 11、q22、q33、q44 is an element in the weight coefficient array Q.
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