Second-level real-time high-precision positioning method and system based on code pseudorange

文档序号：1888066 发布日期：2021-11-26 浏览：26次中文

阅读说明：本技术 一种基于码伪距的秒级实时高精度定位方法与系统 (Second-level real-time high-precision positioning method and system based on code pseudorange ) 是由蒙艳松田野边朗王瑛严涛李天� 周泉于 2021-07-29 设计创作，主要内容包括：本发明涉及一种基于码伪距的秒级实时高精度定位系统及方法,所述的系统包括北斗、GPS、Galileo组成的GNSS星座、低轨卫星星座、地面站、用户终端；所述的低轨卫星星座用于播发与GNSS同频的导航信号,以及在1518MHz～1525MHz播发导航增强电文；所述的地面监测站用于接收GNSS卫星导航信号和低轨卫星星座播发的导航信号；所述主控中心用于接收地面监测站的数据,生成GNSS卫星和低轨卫星的星历和载波相位偏差,同时根据地面监测站的密度生成区域/全球的大气延迟模型,得到导航增强电文；所述地面信关站通过馈电上行链路与低轨卫星星座建立连接,将主控中心生成的导航增强电文上注到低轨卫星星座；所述用户终端用于接收和处理GNSS卫星的导航信号和导航增强电文,得到码伪距并进行定位。(The invention relates to a second-level real-time high-precision positioning system and a method based on code pseudo-range, wherein the system comprises a GNSS constellation consisting of Beidou, a GPS and Galileo, a low-orbit satellite constellation, a ground station and a user terminal; the low-orbit satellite constellation is used for broadcasting navigation signals with the same frequency as the GNSS and broadcasting navigation enhancement messages at 1518 MHz-1525 MHz; the ground monitoring station is used for receiving GNSS satellite navigation signals and navigation signals broadcast by a low earth orbit satellite constellation; the main control center is used for receiving data of the ground monitoring station, generating ephemeris and carrier phase deviation of a GNSS satellite and a low-orbit satellite, and generating a regional/global atmosphere delay model according to the density of the ground monitoring station to obtain a navigation enhancement message; the ground gateway station establishes connection with a low-orbit satellite constellation through a feed uplink, and the navigation enhancement message generated by the main control center is injected to the low-orbit satellite constellation; and the user terminal is used for receiving and processing the navigation signal and the navigation enhancement message of the GNSS satellite to obtain the code pseudo range and positioning.)

1. A second-level real-time high-precision positioning system based on code pseudorange is characterized in that: the system comprises a GNSS constellation consisting of Beidou, a GPS and Galileo, a low orbit satellite constellation, a ground station and a user terminal; the ground station comprises a ground monitoring station, a master control center and a gateway station;

the low-orbit satellite constellation is used for broadcasting navigation signals with the same frequency as the GNSS and broadcasting navigation enhancement messages at 1518 MHz-1525 MHz;

the ground monitoring station is used for receiving GNSS satellite navigation signals and navigation signals broadcast by a low earth orbit satellite constellation, and generating code pseudo range and carrier phase observed quantity data;

the main control center is used for receiving data of the ground monitoring station, generating precise ephemeris and carrier phase deviation of a GNSS satellite and a low-orbit satellite, and generating a regional/global atmosphere delay model according to the density of the ground monitoring station to finally form a navigation enhancement message;

the ground gateway station establishes connection with a low-orbit satellite constellation through a feed uplink, and the navigation enhancement message generated by the main control center is injected to the low-orbit satellite constellation;

the user terminal is used for receiving and processing navigation signals and navigation enhancement messages of GNSS satellites and low orbit satellites to obtain code pseudo-ranges, and positioning is carried out by utilizing the code pseudo-ranges.

2. The system of claim 1, wherein: the user terminal carries out positioning by using the code pseudo range in the following modes:

s1, judging whether the atmospheric delay model of the corresponding area/the whole world broadcasted by the low orbit satellite is received or not, if so, positioning by a PPP-RTK positioning method based on the code pseudo range; if not, go to S2;

s2, judging whether the carrier-to-noise ratio of the navigation signals of the GNSS satellite and the low-orbit satellite is lower than 45dB-Hz, and if not, positioning by using the double-frequency ionosphere-free combination; otherwise, judging whether the realization precision is required to be at the second-level instantaneity of a decimeter level, if so, turning to S3, otherwise, turning to S4;

s3, fixing the ambiguity of the ultra-wide lane and the widelane by 100% by using multi-frequency carrier phase data in the navigation enhancement message, and obtaining the observed quantity of the ambiguity fixation of the ultra-wide lane and the widelane; combining the observation quantity without ionospheric ambiguity by using the fixed ambiguity observation quantity of the ultra-wide lane and the wide lane to realize instantaneous positioning;

s4, realizing 100% widelane ambiguity fixation in the first epoch by using code pseudo-range observed quantity; after the ambiguity of the wide lane is determined, the ambiguity of the narrow lane is fixed through a plurality of epochs by using the observation quantity for fixing the ambiguity of the super-wide lane and the ambiguity of the wide lane provided by S3.

3. The system according to claim 1 or 2, characterized in that: the user terminal improves the measurement precision of the code pseudo range through a broadband signal coherent joint receiving method to obtain the code pseudo range observed quantity; the coherent joint receiving method of the broadband signals comprises the following steps: and processing a signal with a difference value between two central frequency points of 10 MHz-100 MHz broadcasted by the same GNSS satellite or low-earth satellite constellation as a broadband signal.

4. The system of claim 2, wherein: the PPP-RTK positioning method based on the code pseudorange comprises the following steps:

s1: the ground monitoring station receives navigation signals and navigation enhancement messages of GNSS satellites and low-orbit satellites, generates atmospheric delay corresponding to the monitoring station through precise single-point positioning, and transmits the position of the monitoring station and the atmospheric delay to a master control center;

s2: the main control center generates an atmosphere delay model corresponding to the region/the whole world by using the data of S1, and uploads the atmosphere delay model to the low-orbit satellite through the ground gateway station;

s3: after receiving a navigation enhancement message containing an atmospheric delay model, a user terminal calculates the atmospheric delay corresponding to the position of the user terminal by using the atmospheric delay model based on the initial position of the user terminal;

s4: and the user realizes the second-level real-time high-precision positioning by using the code pseudo range and the atmosphere delay calculated by the S3.

5. The system of claim 4, wherein: the error of the initial position of the user terminal in S3 is required to be within 1000 m.

6. The system of claim 1, wherein: the user terminal is provided with an anti-multipath antenna for receiving signals, and the anti-multipath antenna and the radio frequency channel support the signal receiving capacity of the bandwidth range of 0-100 MHz.

7. The system of claim 1, wherein: the GNSS constellation and the low-orbit satellite constellation broadcast three-frequency or multi-frequency navigation signals, and the multi-frequency is more than three frequencies.

8. The system of claim 1, wherein: the low-orbit satellite constellation broadcasts signals of ground level (-145dBW to-120 dBW) in 1518 MHz-1525 MHz, and supports high-speed broadcast of navigation enhancement messages.

9. A second-level real-time high-precision positioning method based on code pseudorange is characterized by comprising the following steps:

a GNSS constellation broadcasts a navigation signal, and a low-orbit satellite constellation broadcasts a navigation signal with the same frequency as the GNSS;

the ground monitoring station receives navigation signals broadcast by a GNSS and a low-orbit satellite constellation, transmits the navigation signals to the master control center, generates ephemeris and carrier phase deviation of the GNSS satellite and the low-orbit satellite by the master control center, and generates a regional/global atmosphere delay model according to the density of the ground monitoring station to obtain a navigation enhancement message;

the navigation enhancement message generated by the master control center is injected to a low-orbit satellite constellation through a ground gateway station, and the navigation enhancement message is broadcast by the low-orbit satellite constellation at 1518 MHz-1525 MHz;

and the user terminal receives and processes the navigation signal and the navigation enhancement message of the GNSS satellite to obtain a code pseudo-range, and the code pseudo-range is utilized for positioning.

10. The method of claim 1, wherein: the user terminal carries out positioning by using the code pseudo range in the following modes:

s2, judging whether the signal carrier-to-noise ratio mentioned above is lower than 45dB-HZ, if not, positioning by using the double-frequency non-ionosphere combination; otherwise, judging whether the second-level real-time performance is required to be realized, if so, switching to S3, otherwise, switching to S4;

Technical Field

The invention belongs to the field of satellite navigation enhancement, and relates to a method and a system for realizing second-level real-time high-precision positioning.

Background

With the rise and development of new generation intelligent science and technology and industrial revolution characterized by "nobody, intelligent connection and thing connection", users and demands of GNSS high-precision services have changed significantly: high-precision users gradually develop from the professional industry fields such as surveying and mapping, engineering measurement and marine resource detection to the mass industry or the mass user field, typical users are new-generation intelligent traffic users represented by automatic driving, and the scale of the automatic driving is about ten million in the future; the user's demand for high-precision services is developed from pure precision to real-time high precision with high integrity and high availability.

At present, the coverage range of the global basic navigation service and the wide area differential positioning service is wide, but the positioning precision can only reach the meter level. High-precision Positioning technologies such as PPP (precision Point Positioning), PPP-AR (precision Point Positioning-amplitude solution), network RTK (Real-time Kinematic), PPP-RTK (Real-time Kinematic) mainly depend on using a high-precision carrier phase measurement value, and always have a problem of solving carrier phase Ambiguity. Carrier phase ambiguity is highly coupled with various errors, and is a main factor influencing positioning convergence. Although many technologies can effectively solve the problem of ambiguity resolution at present, in scenes with a wide application range, such as cities, high-quality and continuous carrier phase measurement has high requirements on a terminal and an observation environment, and is limited in practical use, so that the application of realizing second-level real-time high-precision positioning by using carrier phases is limited.

Disclosure of Invention

The technical problem solved by the invention is as follows: in order to solve the technical problem, the invention discloses a second-level real-time high-precision positioning method and system based on code pseudorange.

The technical scheme of the invention is as follows: a second-level real-time high-precision positioning system based on code pseudo-range comprises a GNSS constellation consisting of a Beidou, a GPS and a Galileo, a low-orbit satellite constellation, a ground station and a user terminal; the ground station comprises a ground monitoring station, a master control center and a gateway station;

the low-orbit satellite constellation is used for broadcasting navigation signals with the same frequency as the GNSS and broadcasting navigation enhancement messages at 1518 MHz-1525 MHz;

Preferably, the user terminal uses the code pseudorange for positioning by the following method:

Preferably, the user terminal improves the measurement precision of the code pseudo range through a broadband signal coherent joint receiving method to obtain the code pseudo range observed quantity; the coherent joint receiving method of the broadband signals comprises the following steps: and processing a signal with a difference value between two central frequency points of 10 MHz-100 MHz broadcasted by the same GNSS satellite or low-earth satellite constellation as a broadband signal.

Preferably, the positioning by the method for PPP-RTK positioning based on code pseudorange comprises the following steps:

s4: and the user realizes the second-level real-time high-precision positioning by using the code pseudo range and the atmosphere delay calculated by the S3.

Preferably, the initial position error of the user terminal in S3 is required to be within 1000 m.

Preferably, the user terminal is equipped with an anti-multipath antenna for receiving signals, and the anti-multipath antenna and the radio frequency channel support the signal receiving capability within the bandwidth range of 0-100 MHz.

Preferably, the GNSS constellation and the low earth orbit satellite constellation broadcast a tri-frequency or multi-frequency navigation signal, and the multi-frequency is more than three frequencies.

Preferably, the low-orbit satellite constellation broadcasts signals of ground level (-145dBW to-120 dBW) in 1518MHz to 1525MHz, and supports high-speed broadcast of navigation enhancement messages.

A second-level real-time high-precision positioning method based on code pseudorange comprises the following steps:

a GNSS constellation broadcasts a navigation signal, and a low-orbit satellite constellation broadcasts a navigation signal with the same frequency as the GNSS;

Preferably, the user terminal uses the code pseudorange for positioning by the following method:

Compared with the prior art, the invention has the beneficial effects that:

the invention discloses a second-level real-time high-precision positioning method and system based on code pseudo-range, which provide second-level real-time high-precision positioning service and can enhance and supplement the real-time performance and reliability of the current GNSS high-precision service. In order to realize the second-level real-time public security precision positioning based on the code pseudo range, the invention discloses a broadband signal coherent joint receiving method and a real-time high-precision positioning method based on the code pseudo range. Compared with the prior art, the method disclosed by the invention has the following advantages:

(1) the existing high-precision positioning system or high-precision enhancement system mainly utilizes carrier phase measurement values, and pseudo-range measurement values are mainly used as reference. The carrier phase measurement value has the advantages of high measurement precision and small influence of multipath, but the ambiguity always needs to be solved, and is highly coupled with various errors, so the positioning real-time performance of the carrier phase measurement value is influenced, and sometimes the ambiguity is fixed incorrectly. The invention provides a broadband signal coherent joint receiving method, which can be used for carrying out coherent joint receiving on signals of two adjacent frequency bands serving as a broadband signal on the basis of the existing transmitted signal, thereby improving the measurement precision of a code pseudo range. And data processing is carried out in a classified mode according to the carrier-to-noise ratio during signal receiving, and real-time high-precision positioning or rapid fixing of the ambiguity of the auxiliary carrier phase measurement value is always carried out by using the high-precision code pseudo range measurement value.

(2) In the existing literature or constructed and implemented PPP-RTK system, the main principle is that on the basis of real-time high-precision orbit and clock error, each monitoring station is used to solve the carrier phase fractional deviation in the area, then the PPP fixed solution is used to solve the troposphere and ionosphere corrections with integer characteristics under the constraint of integer space, and these corrections are broadcast to the user for use, thereby improving the real-time performance of positioning. The PPP-RTK positioning method and system based on the code pseudorange simplify the setting of a PPP-RTK system based on a carrier phase measured value, do not need to solve each error on the basis of ambiguity fixing solution, simplify the flow and improve the real time and the reliability of the system.

Drawings

FIG. 1 is a schematic diagram of a second-level real-time high-precision positioning system based on code pseudorange according to the present invention;

FIG. 2 is a diagram of a coherent joint receiving method for broadband signals;

FIG. 3 is a diagram of a second-level real-time high-precision positioning method based on code pseudoranges;

FIG. 4 shows the spectrum and code tracking error of a coherent and combined received signal of Beidou tri-band and low-orbit satellites B1I and 1518-1525 MHz;

FIG. 5 is a PPP-RTK positioning system based on code pseudoranges;

FIG. 6 is a flow comparison of a PPP-RTK system based on carrier phase measurements and a PPP-RTK system based on code pseudoranges;

fig. 7 is a diagram of measurement errors of wide lanes formed by coherent joint reception of multi-frequency signals.

Detailed Description

The invention will be further elucidated with reference to the embodiments shown in fig. 1 to 7.

The invention provides a second-level real-time high-precision positioning system based on a code pseudo range, which comprises a GNSS constellation consisting of Beidou, a GPS and Galileo, and also comprises a low-orbit satellite constellation (broadcasting a navigation signal with the same frequency as the GNSS and broadcasting a navigation enhancement message in a frequency band (1518 MHz-1525 MHz)); the low orbit satellite constellation supports fast dissemination of navigation enhancement messages (the navigation enhancement messages include ephemeris for GNSS satellites and low orbit satellites, carrier phase bias for multifrequency signals, regional/global high accuracy atmospheric delay models). The system also comprises a ground monitoring station, a master control center and a gateway station. The ground monitoring station is mainly used for receiving GNSS satellite navigation signals and low-orbit satellite navigation signals; the main control center receives the navigation signal of the monitoring station, generates the precise ephemeris and the carrier phase deviation of the GNSS satellite and the low orbit satellite, and simultaneously can generate a high-precision atmosphere delay model of a corresponding area or the whole world if the ground monitoring station is distributed every 10km to 100km, and finally forms a navigation enhancement message; and the ground gateway station injects the navigation enhancement message generated by the main control center to the low-orbit navigation satellite through the feeder uplink.

The GNSS satellite navigation system also comprises a user terminal, wherein the user terminal can receive and process the navigation signals of the GNSS satellite and the low-orbit satellite navigation signals, and meanwhile, the user terminal has strong anti-multipath capability.

After receiving the multi-frequency navigation signals of the GNSS satellite and the low-orbit satellite, the user can improve the measurement precision of the code pseudo range through a broadband signal coherent joint receiving method. The coherent joint receiving method of the broadband signals comprises the following steps: the receiving channel and the digital processing part take two signals with similar frequencies (the difference value of central frequency points is 10 MHz-100 MHz) broadcast by the same GNSS satellite or low earth orbit satellite as a broadband signal for processing, and two coherent signals are taken as a broadband signal for combined processing, so that the measurement precision of the code pseudo range can be improved.

And the user terminal uses the coherent and joint receiving of the broadband signals to obtain the code pseudo range for positioning. According to whether a user receives a regional/global high-precision atmospheric delay model and the carrier-to-noise ratio of a received signal, a second-level real-time high-precision positioning method based on code pseudo-range can be divided into three processing methods, and the user selects according to a use scene.

3.1 a second-level real-time high-precision positioning method based on code pseudo-range: when the area/global high-precision atmosphere delay model information does not exist, when the signal carrier-to-noise ratio exceeds 45dB-Hz, the tracking error of a code pseudo range is small (centimeter level), the code pseudo range can be directly positioned by utilizing the double-frequency ionosphere-free combination, the code pseudo range does not need to be subjected to carrier phase ambiguity resolution, and high-precision positioning (horizontal 10 centimeters) can be instantly realized;

3.2 method based on code pseudo range fast fixed carrier phase ambiguity: when the signal-to-carrier-to-noise ratio is lower than 45dB-HZ and the tracking error of the code pseudo range is larger in the absence of regional/global high-precision atmosphere delay model information, the steps of the positioning method are as follows:

s1.1, by using multi-frequency carrier phase data, realizing the fast fixation of ambiguity of ultra-wide lane and wide lane (the code pseudo range measurement precision of multi-frequency signal coherent joint receiving is far higher than the traditional single signal receiving precision)

S1.2, the ultra-wide lane and wide lane ambiguity-fixed observed quantities obtained in S1.1 are combined into an ionosphere-free ambiguity-free observed quantity, and instantaneous high-precision positioning (horizontal 15 cm) is achieved.

The positioning in the two steps has high real-time performance, but the positioning accuracy is slightly inferior to the accuracy after convergence of the observed quantity by the carrier phase. For some users with low real-time requirements, in order to realize the positioning accuracy with the level less than 5 centimeters, the positioning method comprises the following steps:

s1.3.1 use wideband signal coherent joint received code pseudo range observation to realize 100% wide lane ambiguity fixation in the first epoch.

S1.3.2, after determining the widelane ambiguity, fixing the widelane ambiguity by several epochs by using the observation quantity for fixing the widelane ambiguity and the widelane ambiguity provided by S1.2.

3.3 PPP-RTK (precision Point Positioning-Real-time Kinematic) Positioning method based on code pseudo-range, when there is regional/global high-precision atmosphere delay model, PPP-RTK based on code pseudo-range measurement, because the broadband signal coherent joint receives pseudo-range measurement error is smaller, does not have the factor of the fixed ambiguity at the same time, characterized by that the regional reference station can not produce the ionosphere, troposphere information based on the fixed solution of ambiguity, need not consider the problem of solving the atmosphere delay under the integer space, has reduced the calculation procedure of the service end, increase the Real-time.

The PPP-RTK positioning method based on the code pseudo-range can eliminate the ionized layer without using a combination coefficient because a high-precision atmosphere delay model is known, reduces the amplification of noise after combination and can realize second-level real-time high-precision positioning.

Example 1

The invention discloses a second-level real-time high-precision positioning system based on code pseudo-range, as shown in figure 1, comprising:

1. GNSS/low earth satellite constellation. The GNSS constellation is a current Beidou, GPS and Galileo system, and three systems broadcast multi-frequency signals, wherein the Beidou III system broadcasts B1I, B1C, B2 and B3 signals, the GPS broadcasts L1, L2 and L5 signals, and the Galileo system broadcasts E1, E5 and E6 signals; the low-earth orbit satellite can broadcast a tri-band signal universal to GNSS and can broadcast a navigation enhancement message in a frequency band (1518 MHz-1525 MHz), thereby reducing the time for a user to receive the message.

2. And (4) a ground station. The ground station comprises a monitoring station, a main control center and a gateway station. The ground monitoring station is mainly used for receiving GNSS downlink signals (namely navigation signals) and navigation signals which are broadcasted by low earth orbit satellites and have the same frequency with the GNSS; the main control center receives the navigation signal of the monitoring station, is used for generating precise ephemeris (orbit, clock error) and carrier phase deviation of high-precision GNSS/low-orbit satellite, and can generate a regional/global high-precision atmospheric delay model according to the density of the ground monitoring station; the ground gateway station establishes connection with the low-orbit navigation enhancement satellite through a feed uplink, and injects various high-precision correction numbers (navigation enhancement messages) generated on the ground to the low-orbit navigation enhancement satellite.

3. And a user side. The user terminal can simultaneously receive the GNSS downlink signal and the navigation enhancement message and carry out high-precision and fast convergence positioning; the user side can receive multi-frequency navigation signals broadcast by a GNSS/LEO satellite constellation; the user side can realize coherent joint receiving of a plurality of frequency point broadband signals, and the pseudo range precision is improved; the user terminal is provided with an anti-multipath antenna (the anti-multipath antenna and a radio frequency channel support the signal receiving capability within the bandwidth range of 0-100 MHz), has the sensitivity analysis capability of multipath and also has the anti-multipath capability.

4. A method for coherent joint reception of wideband signals. Taking beidou No. three as an example, as shown in fig. 4, B2a and B2B, B2B and B3I, B1I and B1C, and 1518-1525 MHz signals and B1I signals are received in a coherent and combined manner, and fig. 4 shows code tracking errors when the signals are received in a coherent and combined manner, and the multi-frequency broadband signal correlation and combined reception reduces measurement noise of a pseudorange and improves positioning accuracy. The tracking accuracy of L2 and L5 of GPS is similar to that of B2B and B3I, the tracking accuracy of E5a and E5B of Galileo is similar to that of B2B and B3I, and the coherent joint receiving accuracy of E5B and E6 is similar to that of B2B and B3I. Under the normal condition, the carrier-to-noise ratio of the receiver is about 45dB-HZ (the carrier-to-noise ratio is higher under the conditions of high elevation angle and the like), correspondingly, when in coherent joint receiving, the code tracking error difference of B2a + B2B, B2B + B3I and B1I + B1C under the thermal noise is respectively about 1.5-2 cm, 0.8-1 cm, 3-4 cm and 2-2.5 cm through coherent joint receiving of over-broadband signals, so that a broadband signal (higher than the bandwidth of a traditional navigation signal) is formed, the code tracking error under the thermal noise is improved, and the error is far lower than the code tracking error when a single signal is received at present. The receiver adopts effective anti-multipath design and multipath sensitivity analysis, can effectively reduce the interference of multipath on pseudo-range measurement values, further improves the precision of code pseudo-range measurement values, and simultaneously adopts coherent joint reception of broadband signals, so that the anti-multipath capability is better than that of single signal reception. And obtaining a code pseudo-range measured value with higher precision for second-level real-time high-precision positioning through the coherent joint receiving of the broadband signals.

And 5, a second-level real-time high-precision positioning method based on the code pseudorange.

Taking the beidou third satellite and the low orbit satellite as examples, when the broadband signal coherently and jointly receives the beidou third satellite or the low orbit satellite signal, the center frequency of the signal is shown in the following table:

TABLE 1 center frequency of signal in Beidou III coherent joint reception

f₁	B1I+B1C	1568.259MHz
			f₂	B2b+B3	1237.830MHz
f₃	B2a+B2b	1191.795MHz
			f₄	1521MHz+B1I	1541.14MHz

(1) Second-level real-time high-precision positioning method based on code pseudo range

When the user does not receive the regional/global high-precision atmospheric delay model, and when the signal carrier-to-noise ratio exceeds 45dB-Hz, it can be seen from fig. 4 that the code pseudorange tracking error is small (centimeter level), and the following positioning can be performed by using the dual-frequency ionosphere-free combination (which can use the measurement data of the beidou, Galileo and low-orbit satellites):

the code pseudorange does not need to solve the carrier phase ambiguity, and high-precision positioning (10 cm horizontally) can be instantly realized.

(2) Method for rapidly fixing carrier phase ambiguity based on code pseudorange (S1.1 and S1.2)

When the signal carrier-to-noise ratio is lower than 45dB-HZ, the code pseudorange has larger tracking error, the method shown in the step (1) is directly utilized, the positioning accuracy is poor, firstly, three-frequency carrier phase data (utilizing measurement data of Beidou and low-orbit satellites) are utilized to realize the rapid fixation of the ambiguity of the ultra-wide lane and the wide lane by 100% (the code pseudorange measurement accuracy received by the coherent combination of the multi-frequency signals is far higher than the receiving accuracy of the traditional single signal), then, the observation quantity without the ionospheric ambiguity is combined by utilizing the observation quantity fixed by the ambiguity of the ultra-wide lane and the wide lane, and the instantaneous high-accuracy positioning (the level is 15 cm) is realized. The following steps are specific:

three frequencies received by coherent combination are fully utilized, three-frequency data are utilized to carry out rapid convergence positioning, and the combination of an ultra-wide lane and a wide lane is as follows:

the wide-lane wavelength of the double-frequency combination is far larger than the measurement error, the wide-lane ambiguity can be instantly fixed, the phase decimal deviation can be eliminated through average and single difference, and the wide-lane measurement value and the measurement error are as follows:

andafter the two widelane ambiguities are fixed, a new observation quantity 1 expression is combined, and errors are as follows:

wide lane and L_ewAfter the ambiguity of the ultra-wide lane is fixed, a new observation quantity 2 expression is combined, and errors are as follows:

wide lane and L_ewAfter the ambiguity of the ultra-wide lane is fixed, a new observation quantity 3 expression is combined, and errors are as follows:

when the measurement error of the carrier phase is about 1 mm, a new observed quantityThe measurement error of the method is about ten centimeters and several centimeters, and when the error of coherent joint receiving is large, a new observed quantity is utilizedAnd high-precision positioning is realized.

(3) Method for rapidly fixing carrier phase ambiguity based on code pseudorange (S1.3)

The methods shown in S1.1 and S1.2 have high real-time positioning, but the positioning accuracy is slightly inferior to the accuracy after convergence of the observed quantity using the carrier phase. For some users with low real-time requirements, the following method can be utilized to realize the positioning accuracy with the level less than 5 centimeters. Firstly, the coherent joint received code pseudorange observed quantity is utilized to realize the fixation of 100% of the widelane ambiguity in the first epoch, and after the widelane ambiguity is determined, the observed quantity provided in the steps (1) and (3) is utilized to realize the fixation of the widelane ambiguity through a plurality of epochs. For widelane ambiguity, the solution is as follows:

in the above formula, the wavelength of the wide lane and the combined observation L for determining the ambiguity of the wide lane_wThe measurement error of (a) is expressed as follows:

whether the ambiguity of the wide lane can quickly fix the wavelength and L of the main and wide lanes_wIs determined by the measurement error of (1), wherein L_wThe measurement error of (2) is mainly determined by the measurement error of the carrier phase and the pseudo range.

In coherent joint reception, assuming that the measurement errors of the carrier phases are all 2 mm, the wavelength and the measurement error of the wide lane and the ultra-wide lane in different combinations are respectively shown in the following table, and it can be seen that the combined observed quantity L for determining the ambiguity of the wide lane is determined under different carrier-to-noise ratios_wThe measurement error of the method is far smaller than the wavelength of the wide lane, 100% wide lane ambiguity fixation can be realized in the first epoch, and meanwhile, the situation of mistakenly fixing the wide lane ambiguity cannot occur due to the very small measurement error of the wide laneSee fig. 7.

After the widelane ambiguity is determined, the widelane ambiguity is determined next, and the measurement errors of the widelane wavelength and the carrier phase observed quantity are respectively shown as the following formula:

after the widelane ambiguity is determined, and the widelane ambiguity can be fixed through several epochs by using observed quantity double-frequency ionosphere-free pseudo-range observed quantity or three-frequency ionosphere-free ambiguity fixed observed quantity provided by the middle S1.1 and the S1.2.

4 PPP-RTK positioning method based on code pseudo range

In order to realize higher precision and second-level real-time positioning, the invention provides a PPP-RTK positioning method based on code pseudo range. When the multi-frequency signal is received in a coherent and combined mode, no matter how accurate the pseudo range is, a new observed quantity error is increased due to the influence of a combination coefficient of a ionosphere, and if the measurement accuracy of the pseudo range is high enough and a priori high-precision atmosphere delay model is provided, instantaneous precision positioning can be achieved through the pseudo range-based PPP-RTK positioning method. Fig. 5 is a schematic block diagram of a pseudorange based PPP-RTK positioning method, and fig. 6 is a comparison with a carrier based PPP-RTK system.

The PPP-RTK positioning method based on the code pseudo range comprises the following steps:

s4: and the user realizes the second-level real-time high-precision positioning by using the code pseudo range and the atmosphere delay calculated by the S3.

A PPP-RTK system based on carrier phase observed quantity needs corresponding carrier phase fractional deviation information, meanwhile, a reference station for generating ionosphere troposphere enhancement information needs to realize PPP fixed solution, various error information of the ionosphere and the troposphere is continuously decomposed on the premise of ensuring an integer space, finally, the uniformly matched precise orbit, clock error, phase fractional deviation, ionosphere delay, troposphere delay and the like are broadcasted to a user for use, and the user realizes quick ambiguity fixation by using the information. In this system, three layers of processing are required: 1 precision orbit and clock error; 2 corresponding carrier phase UPD; 3 corresponding ionospheric, tropospheric delays.

In the PPP-RTK system based on pseudo-range measurement, because the multi-frequency signal coherent joint receiving pseudo-range measurement error is small, and meanwhile, the factor of fixed ambiguity does not exist, the regional reference station can not generate ionosphere and troposphere information based on ambiguity fixed solution, the problem of solving the atmospheric delay in an integer space does not need to be considered, the calculation process of a server side is reduced, and the real-time performance is improved. Meanwhile, because a high-precision atmospheric delay model is known, an ionosphere can be eliminated without using a combination coefficient, the amplification of noise after combination is reduced, and second-level real-time high-precision positioning can be realized.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.

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Second-level real-time high-precision positioning method and system based on code pseudorange

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