阅读说明：本技术 基于时间实验室增强信息的北斗局域精密时间传递方法 (Beidou local precise time transfer method based on time laboratory enhancement information ) 是由 涂锐 卢晓春 张鹏飞 张睿 韩军强 范丽红 鲁洋为 于 2020-05-08 设计创作，主要内容包括：本发明公开了一种基于时间实验室增强信息的北斗局域精密时间传递方法,包括：建设北斗基准站,将接收机时钟连接中国科学院国家授时中心时间实验室的标准时间信号,基于北斗基准站的观测值,提取含有标准时间信号的北斗卫星增强信息,并通过网络形式进行播发,时间用户接收到增强信息,并结合采集的观测数据和接收的星历产品,进行非差PPP解算,获取与标准时钟的时差,从而实现国家标准时间的精密时间传递。本发明方法能够消除或削弱共性误差,提高观测值误差修正水平,提高时间传递精度,可以提高用户站观测值误差的修正水平。(The invention discloses a Beidou local precise time transfer method based on time laboratory enhancement information, which comprises the following steps of: the method comprises the steps of building a Beidou reference station, connecting a receiver clock with a standard time signal of a national time service center time laboratory of China academy of sciences, extracting Beidou satellite enhanced information containing the standard time signal based on an observed value of the Beidou reference station, broadcasting the enhanced information in a network form, receiving the enhanced information by a time user, combining collected observation data and a received ephemeris product, performing non-differential PPP resolving, and obtaining time difference with the standard clock, so that precise time transmission of national standard time is realized. The method can eliminate or weaken common errors, improve the error correction level of the observed value, improve the time transfer precision and improve the correction level of the observed value error of the user station.)

1. A Beidou local precise time transfer method based on time laboratory enhancement information is characterized by mainly comprising the following steps of:

s1 Beidou reference station erection modulation: erecting a Beidou reference station, and connecting a receiver clock with a 1PPs standard time signal of a time laboratory of a national time service center of the Chinese academy of sciences;

s2 reference station data acquisition: acquiring double-frequency pseudo range and phase observation data of a Beidou satellite on a reference observation station and auxiliary data required by data processing;

s3 enhanced information extraction: preprocessing the data of the reference station, detecting the cycle slip to obtain a result, correcting errors of relativity, tide, an antenna phase center, a troposphere and earth autobiography of the preprocessed data based on a precise ephemeris and a strong constraint coordinate, and extracting the enhancement information of each satellite after correction;

s4 enhanced information broadcasting: broadcasting pseudo-range, phase enhancement information and cycle slip detection information of each satellite in a set format through a network;

s5 subscriber station data acquisition: acquiring dual-frequency pseudo range and phase observation data of a Beidou satellite on a user observation station, reference station enhancement information and cycle slip information, and auxiliary data;

s6 time transfer solution: preprocessing the user station data, detecting the cycle slip to obtain a result, correcting errors of relativity, tide, an antenna phase center, a troposphere and earth self-transmission of the preprocessed data, correcting enhanced information, fusing cycle slip information, determining an observation equation and a random model, and performing least square solution to obtain the time difference between the user clock and a standard clock.

2. The Beidou local precise time transfer method based on time laboratory enhancement information as set forth in claim 1, wherein the error correction of relativity, tide, antenna phase center, troposphere and earth self-propagation in the steps S3 and S6 is specifically: relativity and tidal correction were corrected using the model specified in IERS convections 2010, antenna phase center correction was corrected using the igs14.atx model, troposphere correction was corrected using the Saastamoinen model, and earth-borne error correction was corrected using the IERS EOP C04 model.

3. The Beidou local area precise time transfer method based on time laboratory enhancement information as claimed in claim 1, wherein the auxiliary data in the steps S2, S5 specifically includes: precise ephemeris, antenna phase center, earth rotation parameters, accurate coordinates of a measuring station and tide parameters.

4. The Beidou local area precise time transfer method based on time laboratory enhancement information as claimed in claim 1, wherein the data preprocessing of the steps S3 and S6 specifically comprises: and performing quality inspection and gross error elimination on data of the reference station and the user station, and deleting data with incomplete satellite ephemeris or observation values to obtain clean data.

5. The method of claim 1, wherein the relativistic tidal error correction is corrected using a model specified in IERS convections 2010; correcting the error of the antenna phase center by adopting an igs14.atx model; the error correction of the troposphere adopts Saastamoinen model correction, and the error correction of the earth self-propagation error adopts IERS EOP C04 model correction.

6. The Beidou local area precise time transfer method based on time laboratory enhancement information as set forth in claim 1, characterized in that the enhancement information extraction in the step S3 adopts the following observation model:

p and phi represent pseudo range and phase, L is an ionosphere-free combined observation value, R is a reference station mark, Cor represents enhancement information, rho is a station star geometric distance, and model is a modeling error sum and comprises troposphere, relativity, tide, an antenna phase center, troposphere and earth rotation error.

7. The Beidou local area precise time transfer method based on time laboratory enhancement information according to claim 1, characterized in that the user station time transfer solution in the step S6 adopts the following observation model:

wherein, U is a user station mark, A is a unit vector of a satellite and a receiver, x is a user coordinate, C is a light speed, lambda is a wavelength, delta N is a single-difference ambiguity parameter, dt is a time difference parameter, and is observation noise;

the stochastic model was determined as follows:

wherein a is the precision of an observed value, a pseudo range observed value is generally set to be 0.2-0.3 m, a phase observed value is generally set to be 0.002-0.003 m, and theta is a satellite height angle and has a radian unit.

Technical Field

The invention relates to the technical field of precise time service, time synchronization and time-frequency transmission, in particular to a Beidou local precise time transmission method based on time laboratory enhancement information.

Background

Time transfer is an important means for realizing high-precision time synchronization among time users, has wide application requirements in industries such as power networking, 5G communication, financial securities and the like, and a time transfer method based on a satellite technology is one of the important means due to low cost, good continuity and easy implementation.

The method for transmitting the carrier phase Precise Point Positioning (PPP) time in satellite time transmission becomes the current mainstream technology due to high precision and is widely applied to a plurality of time laboratories; however, the current PPP time delivery method has three limitations: firstly, many errors in the non-differential observed value are difficult to process efficiently, and the time transfer precision can be further improved; secondly, the conventional PPP time transmission is realized point-to-point, so that the concurrent use requirements of a large number of users cannot be met; thirdly, the conventional PPP can realize high-precision time transfer only by professional technicians and software, and the operation is complex to implement.

How to further improve the precision of PPP time transfer, satisfy a large amount of concurrent use demands of users, and simple and easy to operate and implement has important value to the industry users in the aspect of time.

Disclosure of Invention

In order to solve the technical problem, the invention provides a Beidou local precise time transfer method based on time laboratory enhancement information.

The technical scheme of the invention is as follows: a Beidou local precise time transfer method based on time laboratory enhancement information mainly comprises the following steps:

s1 Beidou reference station erection modulation: erecting a Beidou reference station, and connecting a receiver clock with a 1PPs standard time signal of a time laboratory of a national time service center of the Chinese academy of sciences;

s2 reference station data acquisition: acquiring double-frequency pseudo range and phase observation data of a Beidou satellite on a reference observation station and auxiliary data required by data processing;

s3 enhanced information extraction: preprocessing the data of the reference station, detecting the cycle slip to obtain a result, correcting errors of relativity, tide, an antenna phase center, a troposphere and earth autobiography of the preprocessed data based on a precise ephemeris and a strong constraint coordinate, and extracting the enhancement information of each satellite after correction;

s4 enhanced information broadcasting: broadcasting pseudo-range, phase enhancement information and cycle slip detection information of each satellite in a set format through a network;

s5 subscriber station data acquisition: acquiring dual-frequency pseudo range and phase observation data of a Beidou satellite on a user observation station, reference station enhancement information and cycle slip information, and auxiliary data;

s6 time transfer solution: preprocessing the user station data, detecting the cycle slip to obtain a result, correcting errors of relativity, tide, an antenna phase center, a troposphere and earth self-transmission of the preprocessed data, correcting enhanced information, fusing cycle slip information, determining an observation equation and a random model, and performing least square solution to obtain the time difference between the user clock and a standard clock.

The precision time transfer method is based on time laboratory enhanced information, common errors are effectively eliminated or weakened, so that the error correction level of the observed value is improved, the time transfer precision is improved, the high-precision enhanced information acquired by the reference station not only comprises time signals, but also comprises some non-modeling errors, the correction level of the observed value error of a user station can be improved, and the concurrent use requirements of a large number of users are met.

Further, the correcting of the errors of the relativity theory, the tide, the antenna phase center, the troposphere and the earth autobiography in the steps S3 and S6 is specifically as follows: relativity and tidal correction were corrected using the model specified in IERS convections 2010, antenna phase center correction was corrected using the igs14.atx model, troposphere correction was corrected using the Saastamoinen model, and earth-borne error correction was corrected using the IERS EOP C04 model. Through error correction of relativity, tide, antenna phase center, troposphere and earth self-propagation, pseudo-range observation value enhancement information of each satellite obtained by a subsequent enhancement information extraction observation model can be improved, so that common errors are reduced or eliminated, the error correction level of the observation values is improved, and the time transfer precision is improved.

Further, the auxiliary data in steps S2 and S5 specifically includes: precise ephemeris, antenna phase center, earth rotation parameters, accurate coordinates of a measuring station and tide parameters.

Further, the data preprocessing of steps S3 and S6 specifically includes: and performing quality inspection and gross error elimination on data of the reference station and the user station, and deleting data with incomplete satellite ephemeris or observation values to obtain clean data. The data acquired by the reference station and the subscriber station are preprocessed, irrelevant or incomplete data and the like can be eliminated, the quality of the acquired data is improved, the extraction accuracy of subsequent enhanced information and the correction level of the subscriber station observation value error are improved, and the precise time transfer of the subscriber is realized.

Further, the extraction of the enhanced information in step S3 adopts the following observation models:

p and phi represent pseudo range and phase, L is an ionosphere-free combined observation value, R is a reference station mark, Cor represents enhancement information, rho is a station star geometric distance, and model is a modeling error sum and comprises troposphere, relativity, tide, an antenna phase center, troposphere and earth rotation error.

Further, the user station time transfer solution in step S6 adopts the following observation model:

wherein, U is a user station mark, A is a unit vector of a satellite and a receiver, x is a user coordinate, C is a light speed, lambda is a wavelength, delta N is a single-difference ambiguity parameter, dt is a time difference parameter, and is observation noise;

the stochastic model was determined as follows:

wherein a is the precision of an observed value, a pseudo range observed value is generally set to be 0.2-0.3 m, a phase observed value is generally set to be 0.002-0.003 m, and theta is a satellite height angle and has a radian unit.

The invention has the beneficial effects that:

(1) the method of the invention eliminates or weakens common errors based on the enhanced information, improves the error correction level of the observed value, improves the time transmission precision, and utilizes the high-precision enhanced information provided by the reference station, wherein the enhanced information not only comprises time signals, but also comprises some non-modeling errors, and can improve the correction level of the error of the observed value of the user station.

(2) The method of the invention enhances the information and adopts a broadcasting mode, can realize independent and autonomous time transmission service of multiple users in the area, can only realize point-to-point passive time service compared with the conventional PPP time transmission method, and adopts the enhanced information broadcasting mode, so that the users can independently and autonomously finish the time transmission, and the number of the users is not limited.

(3) The method is simple and reliable, the user does not increase extra work, the method is convenient to implement in real time, the method can be simply implemented at the user end, external assistance is not needed, the time transfer service can be completed only by adopting the conventional PPP resolving process after the enhancement information is corrected, and in a local area range, due to the fact that the satellite orbit, clock error, atmosphere and other errors are high in correlation, a better result can be obtained by adopting the broadcast ephemeris, and the method is convenient to apply in real time.

Drawings

FIG. 1 is a flow chart of a Beidou local precise time transfer method based on time laboratory enhancement information.

Fig. 2 is enhancement information of a satellite extracted by a reference station in an embodiment.

Fig. 3 is a time difference sequence acquired by the USER station in the specific embodiment.

Detailed Description

The present invention will be further described with reference to the following drawings and examples, which include, but are not limited to, the following examples.

The Beidou local precise time transfer method based on time laboratory enhancement information mainly comprises two core technologies:

1) the method comprises the following steps of extracting enhancement information on a Beidou reference station in a time laboratory, wherein the extraction of the enhancement information adopts the following observation models:

p and phi represent pseudo range and phase, L is an ionosphere-free combined observation value, R is a reference station mark, Cor represents enhancement information, rho is a station star geometric distance, and model is a modeling error sum and comprises troposphere, relativity, tide, an antenna phase center, troposphere and earth rotation error.

2) The time transfer of the user side based on the enhanced information is resolved, and the time transfer of the user side is resolved by adopting the following observation model:

wherein, U is a user station mark, A is a unit vector of a satellite and a receiver, x is a user coordinate, C is a light speed, lambda is a wavelength, delta N is a single-difference ambiguity parameter, dt is a time difference parameter, and is observation noise;

the stochastic model was determined as follows:

wherein a is the precision of an observed value, a pseudo range observed value is generally set to be 0.2-0.3 m, a phase observed value is generally set to be 0.002-0.003 m, and theta is a satellite height angle and has a radian unit.

As shown in fig. 1, the Beidou local precise time transfer method based on time laboratory enhanced information comprises six parts, namely reference station erection modulation, reference station data acquisition, enhanced information extraction, enhanced information broadcasting, user station data acquisition, time transfer calculation based on enhanced information, connection of a receiver clock of a reference station with a standard time signal of a national time service center time laboratory, extraction of enhanced information of each satellite and broadcasting to a time user; after receiving the enhancement information, the time user combines the observation value of the time user to carry out PPP resolving, so that precise time transfer is realized, and the method specifically comprises the following steps:

firstly, the Beidou reference station is erected and modulated

And erecting a Beidou reference station, connecting a receiver clock with a 1PPs standard time signal of a time laboratory of a national time service center of the Chinese academy of sciences, and modulating the receiver clock into a static measurement observation mode.

Second, reference station data acquisition

Selecting 200-day data of 2016 years of NTP1 as an example of a national center docking reference station, and the data sampling interval is 30 s;

and acquiring double-frequency pseudo range and phase observation data of a Beidou satellite on the observation station and auxiliary data required by data processing, wherein the auxiliary data comprises a precise ephemeris, an antenna phase center, an earth rotation parameter, an accurate coordinate of the observation station and a tide parameter.

Third, enhanced information extraction

1) Checking the data quality, eliminating gross errors, deleting data without satellite ephemeris or incomplete observation values to obtain clean data, detecting cycle slip and giving a cycle slip detection result;

2) based on precise ephemeris and strong constraint coordinates, the preprocessed clean data is corrected by relativity, tide, antenna phase center, troposphere and earth rotation error,

wherein relativistic and tidal corrections are corrected using the model specified in IERS Conventions2010, antenna phase center correction is corrected using the igs14.atx model, tropospheric correction is corrected using the Saastamoinen model, and earth rotation error correction is corrected using the IERS EOP C04 model;

3) after the correction, the enhancement information of each satellite is extracted according to the formula (1), and the obtained pseudo-range observed value enhancement information of each satellite is shown in fig. 2.

Fourthly, enhancing information broadcasting

And (4) broadcasting pseudo-range, phase enhancement information and cycle slip detection information of each satellite in a set format through a network.

The fifth step, user data acquisition

The method comprises the steps of obtaining dual-frequency pseudo-range and phase observation data of a Beidou satellite on a user observation station, reference station enhancement information and cycle slip information, and auxiliary resolving parameters including a precise ephemeris, an antenna phase center, earth rotation parameters, accurate coordinates of the observation station and tide parameters.

Sixth, enhanced information based time transfer resolution

1) Performing quality inspection and gross error elimination on data of the user station, deleting data without satellite ephemeris or incomplete observation values to obtain clean data, performing cycle slip detection, and giving a cycle slip detection result;

2) the preprocessed clean data is subjected to relativity, tide, antenna phase center, troposphere and earth self-transmission error correction, enhancement information correction and cycle slip information fusion,

wherein relativistic and tidal corrections are corrected using the model specified in IERS Conventions2010, antenna phase center correction is corrected using the igs14.atx model, tropospheric correction is corrected using the Saastamoinen model, and earth rotation error correction is corrected using the IERS EOP C04 model;

3) determining an observation equation and a random model, and solving the time difference between a user clock and a standard clock by adopting a least square method according to formulas (2) and (3) to realize the precise time transfer of the user;

by taking the USER station USER in 200 days in 2019 as an example, the data sampling interval is 30 seconds, the obtained time difference result is shown in fig. 3, and the graph comparison shows that the adoption of the precise time transmission method can eliminate or weaken common errors, improve the error correction level of the observed value, improve the time transmission precision and improve the correction level of the error of the observed value of the USER station.