CN-121995408-A - Wide-area GNSS time-frequency transmission method, device and equipment based on crowdsourcing RTK technology

CN121995408ACN 121995408 ACN121995408 ACN 121995408ACN-121995408-A

Abstract

A wide-area GNSS time-frequency transmission method, device and equipment based on a crowdsourcing RTK technology are provided, wherein the method comprises the steps of constructing an unbiased single-difference ionosphere and troposphere delay correction model at a server through atmospheric correction information generated by a reference station and a user side in a convergence area based on a single-difference ionosphere weighted observation model, broadcasting atmospheric correction prior information to a time-frequency transmission user, fixing whole-cycle ambiguity with the atmospheric correction prior information to construct a single-difference observation model of the crowdsourcing RTK, and separating pseudo-range hardware delay in clock difference parameters based on the single-difference observation model of the crowdsourcing RTK to only absorb phase hardware delay to form a phase clock model and constructing a corresponding random model. The invention realizes zero short baseline condition The stability of the magnitude breaks through the upper limit of accuracy of the existing GNSS time transfer technology. Meanwhile, the advantages of the crowdsourcing RTK technology in ionosphere space transfer are utilized, and the capability is expanded to a wide area range.

Inventors

CHEN XINGYU
XU HONGJIN
YUAN YUNBIN
OU JIKUN

Assignees

中国科学院精密测量科学与技术创新研究院

Dates

Publication Date: 20260508
Application Date: 20251231

Claims (10)

1. A wide-area GNSS time-frequency delivery method based on crowdsourcing RTK technology, comprising: based on a single-difference ionosphere weighted observation model, constructing an unbiased single-difference ionosphere and troposphere delay correction model at a server through atmospheric correction information generated by a reference station and a user side in a convergence area, transmitting atmospheric correction prior information to a time-frequency transmission user, and fixing integer ambiguity by the atmospheric correction prior information to construct a single-difference observation model of the crowdsourcing RTK; On the basis of a single-difference observation model of the crowdsourcing RTK, only the phase hardware delay is absorbed by separating the pseudo-range hardware delay in the clock difference parameter, so as to form a phase clock model, and a corresponding random model is constructed.
2. The wide-area GNSS time-frequency delivery method based on crowdsourcing RTK technique according to claim 1, wherein the single difference observation model of the crowdsourcing RTK is: ; ; ; ; in the formula, Is a desired operator, superscript The representation of the satellite is given to the satellite, By using Distinguishing between different GNSS constellations And Respectively representing a reference station and a user terminal; for the frequency identification purposes, ; And The pseudo-range and phase O-C single difference observed values are respectively; representing the star distance of a single-difference station; Is a troposphere projection coefficient; delay for relative troposphere between zenith directional stops; in order to have an unbiased single difference ionospheric delay, Is a frequency-dependent term; Is wavelength; is double-difference ambiguity, superscript Representing a reference satellite; And The ionosphere and troposphere prior values are respectively; And Pseudo-range clock difference and phase clock difference respectively; The pseudo-range clock difference and the phase clock difference are as follows: ; ; in the formula, True clock difference for the receiver; pseudo-range hardware delay for the inter-station receiver; delay for inter-station receiver phase hardware; Is ambiguity.
3. The method for wide-area GNSS time-frequency delivery based on crowdsourcing RTK technology as set forth in claim 2, wherein the unbiased single difference ionospheric delay is synchronously returned to the server according to the user-side solution Relative tropospheric delay between zenith directional stops The method is used for constructing a wide-area ionosphere and troposphere delay correction model and broadcasting precise atmosphere correction prior information to a time-frequency transmission user.
4. The wide-area GNSS time-frequency delivery method based on crowdsourcing RTK technique according to claim 1, wherein the phase clock model is: ; ; ; ; in the formula, Is a desired operator, superscript The representation of the satellite is given to the satellite, By using Distinguishing between different GNSS constellations And Respectively representing a reference station and a user terminal; for the frequency identification purposes, ; And The pseudo-range and phase O-C single difference observed values are respectively; Is a single-difference station star distance; Is a phase clock difference parameter; Is a troposphere projection coefficient; delay for relative troposphere between zenith directional stops; Is a frequency-dependent term; is an unbiased single difference ionospheric delay; a pseudo-range hardware delay between receivers; phase hardware delay between the second and above second frequency receivers; Is wavelength; is double-difference ambiguity, superscript Representing a reference satellite; And The ionosphere and troposphere prior values are respectively; The phase clock difference parameters are as follows: ; in the formula, True clock difference for the receiver; for a first frequency phase offset between the receivers; is a first frequency wavelength; Is the single difference ambiguity between stations on the first frequency.
5. The wide-area GNSS time-frequency delivery method of claim 4, wherein the reference satellite is fixed to ensure single-difference ambiguity terms Is a fixed constant.
6. The method for wide-area GNSS time-frequency delivery over crowdsourcing RTK technology as set forth in claim 4, wherein, Phase hardware delay between the second and above second frequency receivers The method comprises the following steps: ; in the formula, Is that Phase hardware delay between receivers on frequency; Is a phase hardware delay between receivers on a first frequency; is a first frequency wavelength; a single difference reference satellite ambiguity between stations on a first frequency; Is that Single difference reference satellite ambiguity between stations on frequency; pseudo-range hardware delay between the receivers The method comprises the following steps: ; in the formula, Is that Pseudo-range hardware delay between receivers on frequency; Is a phase hardware delay between receivers on a first frequency; The satellite ambiguity is referenced for single difference between stations on a first frequency.
7. The wide-area GNSS time-frequency delivery method based on crowdsourcing RTK technique of claim 4 wherein the stochastic model is: ; ; ; ; ; ; ; in the formula, And A variance-covariance matrix of the pseudorange and the phase observations, respectively; a variance component matrix related to the receiver is used for describing the relative difference of the observed noise levels of different receivers; The diagonal element of the variance component matrix related to the pseudo-range observation is the variance of each frequency pseudo-range observation; the diagonal element of the variance component matrix is the variance of the carrier phase observation of each frequency; the variance component matrix is related to the satellite altitude angle and is used for describing the characteristic that the observation noise increases along with the decrease of the satellite altitude angle; Is Kronecker product; a reference station variance component factor; the variance component factor of the user side is used as the variance component factor of the user side; Observing variance for a first frequency pseudo range; Is that Pseudorange observation variance over frequency; Observing a variance for the first frequency phase; Is that Phase observation variance over frequency; Is the first A high-angle correlation variance component corresponding to the satellite; the method is used for describing the reference noise level of GNSS observation under the optimal observation geometry condition; Is the satellite altitude.
8. A wide-area GNSS time-frequency delivery apparatus based on crowdsourcing RTK technology, characterized in that the apparatus is adapted to implement the method of any of the claims 1 to 7, the apparatus comprising: The first model construction module is used for constructing an unbiased single-difference ionosphere and troposphere delay correction model at a server through the atmospheric correction information generated by a reference station and a user side in a convergence area based on a single-difference ionosphere weighted observation model, transmitting the atmospheric correction prior information to a time-frequency transmission user, and constructing a single-difference observation model of the crowdsourcing RTK by fixing integer ambiguity with the atmospheric correction prior information; The second model building module is used for forming a phase clock model by separating pseudo-range hardware delay from clock difference parameters and only absorbing phase hardware delay on the basis of a single-difference observation model of the crowdsourcing RTK, and building a corresponding random model.
9. A wide-area GNSS time-frequency transmission device based on crowdsourcing RTK technology is characterized in that, Comprising a memory and a processor; the memory is used for storing computer program codes and transmitting the computer program codes to the processor; The processor being configured to perform the method of any of claims 1 to 7 according to instructions in the computer program code.
10. A computer readable storage medium, characterized in that the computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements the method according to any of claims 1 to 7.

Description

Wide-area GNSS time-frequency transmission method, device and equipment based on crowdsourcing RTK technology Technical Field The present invention relates to the field of GNSS time transfer technologies, and in particular, to a wide area GNSS time-frequency transfer method, apparatus and device based on a crowdsourcing RTK technology. Background High-precision time and frequency transfer is an important foundation of a modern time-frequency system and a navigation system, and has a key effect in the fields of metering science, GNSS space-time reference maintenance and earth science and space technology. Researches such as relativistic geodetic measurement, gravitational potential difference measurement and reference frame maintenance by means of an optical atomic clock and GNSS are rapidly developed, and time-frequency observation is an important technical approach for improving the geodetic accuracy. With short-term stability breakthrough of optical atomic clockHorizontal, making cross-site time comparison links a key bottleneck limiting the application of optical clocks in areas or even wider scales. Although optical fiber links can achieve time-frequency transmission approaching the intrinsic stability of high-performance atomic clocks, the optical fiber links are limited by construction cost and geographic coverage, wide-area deployment is difficult to form, and GNSS has the advantages of wide coverage, low cost, global deployment and the like, and is considered as a means for achieving the most potential of large-range time-frequency transmission. However, the existing GNSS time-frequency transfer performance is limited toMagnitude, break throughThe magnitude remains challenging. The main challenges are presented by both the integer ambiguity fixing capability and the pseudorange hardware delay processing. On the one hand, a great deal of researches show that the whole-cycle ambiguity is fixed in the models of IPPP, UDUC, SDRTK and the like, and compared with PPP with unfixed ambiguity, the short-term frequency stability can be improved by about 30% -60%. However, because the ionospheric delay and the ambiguity have strong coupling in the observation equation, the success rate of the ambiguity fixing is highly dependent on the refinement of the ionospheric delay. The baseline class models (e.g., SDRTK, UDUC RTK) typically need to switch between fixed, weighted, and floating point strategies based on baseline length or regional ionospheric activity, and lack a uniform constraint framework, resulting in large differences in performance under different regional and spatio-temporal conditions. Although single-station models (such as PPP and IPPP) can reduce the influence through ionosphere combination or ionosphere parameterization, the whole-cycle ambiguity fixing still depends on external precise products and can reach a steady state only by undergoing a longer filtering convergence process. On the other hand, the existing GNSS time-frequency transfer model, whether it be a baseline class model (SDRTK and UDUC RTK) or a single station class model (PPP and IPPP), inevitably absorbs different forms of hardware delay, including pseudo-range hardware delay or hardware delay after frequency combination. Wherein the pseudorange hardware delay is not only high in noise level, but the multi-frequency combination further amplifies the noise, both of which raise the noise floor of the clock-difference sequence, thereby limiting short-term frequency stability. Therefore, there is a need to develop new algorithm frameworks that further attenuate the effects of ionosphere and pseudorange/phase hardware delays on time transfer to achieve higher stability GNSS time-frequency transfer over a wide area. Disclosure of Invention The present invention is directed to overcoming the above-mentioned drawbacks and problems in the prior art, and provides a wide-area GNSS time-frequency transmission method, apparatus and device based on crowdsourcing RTK technology, wherein the wide-area GNSS time-frequency transmission method implements zero short baseline conditionThe stability of the magnitude breaks through the upper limit of precision of the existing GNSS time transfer technology, and meanwhile, the advantages of the crowdsourcing RTK technology in ionosphere space transfer are further utilized, and the capability is expanded to a wide area range. In order to achieve the above object, the technical solution of the present invention is: in a first aspect, the present invention provides a wide-area GNSS time-frequency delivery method based on crowdsourcing RTK technology, including: based on a single-difference ionosphere weighted observation model, constructing an unbiased single-difference ionosphere and troposphere delay correction model at a server through atmospheric correction information generated by a reference station and a user side in a convergence area, transmitting atmospheric correction prior information to a ti