阅读说明：本技术 一种多系统联合卫星导航定位授时装置及方法 (Multi-system combined satellite navigation positioning time service device and method ) 是由 丁慧霞 王智慧 董方云 李健 李占刚 滕玲 张庚 邢亚 杨德龙 王永明 陈端云 于 2021-08-19 设计创作，主要内容包括：本发明公开了一种多系统联合卫星导航定位授时装置及方法,针对定位授时及单独授时两种不同的应用场景,利用接收机位置及时间信息唯一确定的信息,实现了定位及授时结果的可靠性的优化与改进。本发明在授时装置位置未精确标定的应用场景下,授时装置分别采用各系统的观测量单独定位,授时装置的位置是唯一的,因此,可以用这四个系统解算得到的四个位置信息互相进行检核,从而得到可靠性更高的位置及时间信息；通过事先标定的方式获取授时装置的精确位置,利用授时装置的精确位置,各系统根据已知的位置信息对粗差较大的卫星信号观测量进行剔除,并独立进行解算接收机钟差,提高单系统授时精度。(The invention discloses a multisystem combined satellite navigation positioning time service device and a multisystem combined satellite navigation positioning time service method, aiming at two different application scenes of positioning time service and independent time service, and realizing the optimization and improvement of the reliability of positioning and time service results by using the information uniquely determined by the position of a receiver and time information. In an application scene that the position of the time service device is not accurately calibrated, the time service device is independently positioned by adopting the observed quantity of each system, and the position of the time service device is unique, so that four pieces of position information obtained by the four systems through calculation can be checked with each other, and the position and time information with higher reliability can be obtained; the accurate position of the time service device is obtained in a pre-calibration mode, the satellite signal observed quantity with large gross error is removed by each system according to the known position information by utilizing the accurate position of the time service device, the clock error of the receiver is independently calculated, and the time service precision of the single system is improved.)

1. A multisystem combined satellite navigation positioning time service method is characterized by comprising the following steps:

receiving satellite signals of navigation systems, and obtaining the position and UTC time of each navigation system through positioning and resolving the observed quantity of each navigation system;

the positions are checked with each other by using the position confidence coefficient of positioning calculation to obtain the optimal estimation of the position of the receiver, and the optimal estimation positioning result is output;

obtaining time deviation estimation between UTC time of each navigation system through positioning calculation, calculating the UTC time estimation of a certain navigation system according to the time deviation estimation based on the time service result of each navigation system, and finally calculating the optimal estimation of the UTC time of the certain navigation system;

and according to the user configuration, selecting a time service result appointed by the user to output, and outputting an optimal estimated time result.

2. The multi-system joint satellite navigation positioning and timing method according to claim 1, wherein after receiving satellite signals of a navigation system, the navigation system is a GPS navigation system, a BDS navigation system, a Glonass navigation system, or a Galileo navigation system, the method performs observation gross error rejection processing on the received satellite signals to reject observation errors caused by observation noise interference and multipath interference.

3. The multi-system combined satellite navigation positioning time service method according to claim 1, wherein the specific method for performing observation gross error rejection processing on the received satellite signals is as follows:

calculating a pseudo-range residual error between a measured value and a predicted value according to historical information of receiver position estimation; the pseudo-range residual error is the sum of the pseudo-range measured value of the corresponding satellite minus the geometric distance predicted value and the receiver clock error predicted value.

4. The multi-system joint satellite navigation positioning and timing method according to claim 2, wherein the specific method for mutually checking the position information by using the position confidence of the positioning solution is as follows:

s1, initializing the position confidence coefficient of positioning calculation of each navigation system to 0;

s2, calculating the three-dimensional distance of each navigation system to obtain the position by positioning and resolving as follows:

PP_gb＝||P_gps-P_bds||

PP_gr＝||P_gps-P_glo||

PP_ge＝||P_gps-P_gal||

PP_br＝||P_bds-P_glo||

PP_be＝||P_bds-P_gal||

PP_re＝||P_glo-P_gal||

wherein, PP_ijIndicating the receiver position resolved by the GNSS system i and the receiver position resolved by the GNSS system jIs a three-dimensional distance; the values of i, j are as follows: g represents GPS, b represents Beidou, r represents glonass, and e represents Galileo; p_gpsResolving position, P, for GPS_bdsResolving position, P, for BDS_gloResolving the position, P, for Glonass_galResolving the position for Galileo;

s3, calculating the three-dimensional distance of the position according to the positioning and resolving of two different systems and calculating the reliability CL according to the following formula_gb、CL_gr、CL_ge、CL_br、CL_beAnd CL_re：

CL_ij＝1-PP_ij/max(PP_ij)

Wherein, max (PP)_ij) The maximum value of all three-dimensional distance sizes is obtained; CL_ijThe value range is [0, 1]]And the larger the value is, the higher the reliability is;

s4, respectively calculating GPS resolving position P_gpsBDS resolving position P_bdsGlonass solved for position P_gloAnd Galileo solves the position P_galJoint confidence of (PCL)_gps、PCL_bds、PCL_glonassAnd PCL_galileo：

PCL_gps＝CL_gb+CL_gr+CL_ge

PCL_bds＝CL_gb+CL_br+CL_be

PCL_glonass＝CL_gr+CL_br+CL_re

PCL_gaiileo＝CL_ge+CL_be+CL_re

Wherein, PCL_gpsResolving position P for GPS_gpsJoint confidence of (2), PCL_bdsResolving position P for BDS_bdsJoint confidence of (2), PCL_glonassResolving position P for Glonass_gloJoint confidence of (2), PCL_galileoResolving position P for Galileo_galJoint confidence of (3);

if PCL_gps< CLThreshold, adding PCL_gpsThe setting is 0, which indicates that the positioning result of the GPS navigation system has problems;

if PCL_bds< CLThreshold, PCL_bdsSetting the positioning result to be O, which indicates that the BDS navigation system has a problem in the positioning result;

if PCL_glonass< CLThreshold, adding PCL_glonassThe setting is 0, which indicates that the positioning result of the Glonass navigation system has problems;

if PCL_galileo< CLThreshold, adding PCL_galileoThe setting is 0, which indicates that the positioning result of the Galileo navigation system has a problem;

CLThreshold is a threshold value of comprehensive reliability of a positioning result, and an optimal value is obtained by engineering debugging.

5. The multi-system joint satellite navigation positioning and timing method according to claim 2, wherein the time offset estimation is calculated as follows:

under the condition that the positioning credibility of the two systems meets the requirement, filtering estimation of difference values between UTC time obtained by calculation of each system is carried out, and time deviation between A system time and B system time is estimated to be TD_AB ^(k)Calculated from the following formula:

wherein alpha is a filter coefficient, and alpha is in the range of 0, 1](ii) a When alpha is 1, the output of the filter is the measured value of the current resolving moment; therefore, solving the time offset estimate TD between time i, GPS time and BDS time_gb ^(k)The time offset between GPS time and Glonass time is estimated as TD_gr ^(k)The time offset between GPS time and Galileo time is estimated as TD_ge ^(k)Time offset between BDS time and Glonass time to estimate TD_br ^(k)Time offset between BDS time and Galileo time estimate TD_be ^(k)Time deviation between Glonass time and Galileo time to estimate TD_re ^(k)。

6. The multi-system joint satellite navigation positioning and timing method according to claim 5, wherein the specific method for calculating the optimal estimate of the UTC time is as follows:

BDS time service result:

the estimate of UTC time resolved by the BDS is as follows:

s1, BDS time estimation based on GPS time service results:

s2, BDS time estimation based on the Glonass time service result:

s3, BDS time estimation based on the Galileo time service result:

s4.BDS time estimation optimal resultsComprises the following steps:

GPS time service result:

the UTC time estimate resolved by the GPS is as follows:

s1, GPS time estimation based on BDS time service results:

s2, GPS time estimation based on the Glonass time service result:

s3, GPS time estimation based on the Galileo time service result:

s4. optimal result of GPS time estimationComprises the following steps:

glonass timing results:

the Glonass solved UTC time estimate is as follows:

s1, estimating Glonass time based on a GPS time service result:

s2, estimating the Glonass time based on the BDS time service result:

s3, estimating the Glonass time based on the Galileo time service result:

s4.Glonass time estimation optimum resultComprises the following steps:

galileo timing results:

the estimates of UTC time obtained by Galileo solution are as follows:

s1, Galileo time estimation based on a GPS time service result:

s2, Galileo time estimation based on BDS time service results:

s3, Galileo time estimation based on the Glonass time service result:

s4.Galileo time estimation optimal resultComprises the following steps:

wherein: and a, b, c and d mark weight coefficients of UTC time resolved by each system, the value range is [0, 1], a + b + c + d is 1, a corresponds to a BDS time service result, b corresponds to the BDS time of the GPS time service result, c corresponds to the BDS time of the Glonass time service result, and d corresponds to the BDS time of the Galileo time service result.

7. A multisystem combined satellite navigation positioning time service device is characterized by comprising:

the positioning and time service module is used for receiving satellite signals of the navigation systems, and the observed quantity of each navigation system is used for obtaining the position and UTC time of each navigation system through positioning calculation;

the time service position checking module checks positions mutually by using position confidence coefficient of positioning calculation to obtain optimal estimation of the position of the receiver and output an optimal estimation positioning result;

the time checking module is used for obtaining time deviation estimation among the UTC time of each navigation system through positioning calculation, calculating the UTC time estimation of a certain navigation system according to the time deviation estimation based on the time service result of each navigation system, and finally calculating the optimal estimation of the UTC time of the certain navigation system;

and the time service mode selection module is used for selecting a time service result appointed by the user according to the user configuration, outputting the time service result and outputting an optimal estimated time result.

8. The multi-system combined satellite navigation, positioning and time service device of claim 7, further comprising an observed quantity gross error rejection module, wherein the observed quantity gross error rejection module is configured to perform observed quantity gross error rejection processing on the received satellite signals, and reject observation errors caused by observation noise interference and multipath interference.

9. A terminal device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of claims 1-6 when executing the computer program.

10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 6.

Technical Field

The invention belongs to the technical field of positioning time service, and relates to a multi-system combined satellite navigation positioning time service device and method.

Background

The existing timing scheme often focuses on the realization of timing function and the improvement of timing precision, but the consideration of timing reliability under different signal conditions is deficient.

The GNSS signal is a weak signal and is easy to interfere, different satellite signals are broadcast in different signal frequency bands, under a typical application scene, a large number of 1-2 systems are interfered, and positioning and time service results are deteriorated or even wrong. Therefore, in the application scene, the reliability of the positioning and time service of the receiver becomes very useful.

Secondly, each different GNSS system operates and maintains independently, so that in the case that a certain system has a service interruption or precision deterioration in a specific time period, the user still wants the receiver to provide stable and reliable positioning and time service results.

The existing time service scheme jointly resolves the observed quantities of all systems, and has the following defects:

a. when a certain GNSS system has systematic faults, positioning/timing errors of the timing terminal can be caused;

b. satellite navigation signals of different systems are broadcast on different frequencies, and when the signal of a certain frequency point is interfered, the positioning/time service precision of the frequency point is deteriorated, and even the time service result of the frequency point is unavailable.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a multisystem combined satellite navigation positioning time service device and a multisystem combined satellite navigation positioning time service method.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a multisystem combined satellite navigation positioning time service method comprises the following steps:

receiving satellite signals of navigation systems, and obtaining the position and UTC time of each navigation system through positioning and resolving the observed quantity of each navigation system;

the positions are checked with each other by using the position confidence coefficient of positioning calculation to obtain the optimal estimation of the position of the receiver, and the optimal estimation positioning result is output;

obtaining time deviation estimation between UTC time of each navigation system through positioning calculation, calculating the UTC time estimation of a certain navigation system according to the time deviation estimation based on the time service result of each navigation system, and finally calculating the optimal estimation of the UTC time of the certain navigation system;

and according to the user configuration, selecting a time service result appointed by the user to output, and outputting an optimal estimated time result.

The method is further improved in that:

after receiving satellite signals of a navigation system, the navigation system carries out observation gross error elimination processing on the received satellite signals, and eliminates observation errors caused by observation noise interference and multipath interference, wherein the navigation system is a GPS navigation system, a BDS navigation system, a Glonass navigation system and a Galileo navigation system.

The specific method for removing the observed quantity gross error of the received satellite signals is as follows:

calculating a pseudo-range residual error between a measured value and a predicted value according to historical information of receiver position estimation; the pseudo-range residual error is the sum of the pseudo-range measured value of the corresponding satellite minus the geometric distance predicted value and the receiver clock error predicted value.

The specific method for mutually checking the position information by using the position confidence coefficient of positioning calculation is as follows:

s1, initializing the position confidence coefficient of positioning calculation of each navigation system to 0;

s2, calculating the three-dimensional distance of each navigation system to obtain the position by positioning and resolving as follows:

PP_gb＝||P_gps-P_bds||

PP_gr＝||P_gps-P_glo||

PP_ge＝||P_gps-P_gal||

PP_br＝||P_bds-P_glo||

PP_be＝||P_bds-P_gal||

PP_re＝||P_glo-P_gal||

wherein, PP_ijThe position of the receiver obtained by the calculation of the GNSS system i and the position of the receiver obtained by the calculation of the GNSS system j are three-dimensional distances; the values of i, j are as follows: g represents GPS, b represents Beidou, r represents glonass, and e represents Galileo; p_gpsResolving position, P, for GPS_bdsResolving position, P, for BDS_gloResolving the position, P, for Glonass_galResolving the position for Galileo;

s3, calculating the three-dimensional distance of the position according to the positioning and resolving of two different systems and calculating the reliability CL according to the following formula_gb、CL_gr、CL_ge、CL_br、CL_beAnd CL_re：

CL_ij＝1-PP_ij/max(PP_ij)

Wherein, max (PP)_ij) The maximum value of all three-dimensional distance sizes is obtained; CL_ijThe value range is [0, 1]]And the larger the value is, the higher the reliability is;

s4, respectively calculating GPS resolving position P_gpsBDS resolving position P_bdsGlonass solved for position P_gloAnd Galileo solves the position P_galJoint confidence of (PCL)_gps、PCL_bds、PCL_glonassAnd PCL_galileo：

PCL_gps＝CL_gb+CL_gr+CL_ge

PCL_bds＝CL_gb+CL_br+CL_be

PCL_glonass＝CL_gr+CL_br+CL_re

PCL_gaiileo＝CL_ge+CL_be+CL_re

Wherein, PCL_gpsResolving position P for GPS_gpsJoint confidence of (2), PCL_bdsResolving position P for BDS_bdsJoint confidence of (2), PCL_glonassResolving position P for Glonass_gloJoint confidence of (2), PCL_galileoResolving position P for Galileo_galJoint confidence of (3);

if PCL_gps< CLThreshold, adding PCL_gpsThe setting is 0, which indicates that the positioning result of the GPS navigation system has problems;

if PCL_bds< CLThreshold, adding PCL_bdsSetting the positioning result to be O, which indicates that the BDS navigation system has a problem in the positioning result;

if PCL_glonass< CLThreshold, adding PCL_glonassThe setting is 0, which indicates that the positioning result of the Glonass navigation system has problems;

if PCL_galileo< CLThreshold, adding PCL_galileoThe setting is 0, which indicates that the positioning result of the Galileo navigation system has a problem;

CLThreshold is a threshold value of comprehensive reliability of a positioning result, and an optimal value is obtained by engineering debugging.

The calculation method of the time offset estimate is as follows:

under the condition that the positioning credibility of the two systems meets the requirement, filtering estimation of difference values between UTC time obtained by calculation of each system is carried out, and time deviation estimation TB between A system time and B system time_AB ^(k)Calculated from the following formula:

wherein alpha is a filter coefficient, and alpha is in the range of 0, 1](ii) a When alpha is 1, the output of the filter is the measured value of the current resolving moment; therefore, solving the time offset estimate TD between time i, GPS time and BDS time_gb(^k)The time offset between GPS time and Glonass time is estimated as TD_gr ^(k)The time offset between GPS time and Galileo time is estimated as TD_ge ^(k)Time offset between BDS time and Glonass time to estimate TD_br ^(k)Time offset between BDS time and Galileo time estimate TD_be ^(k)Time deviation between Glonass time and Galileo time to estimate TD_re ^(k)。

The specific method for calculating the optimal estimate of UTC time is as follows:

BDS time service result:

the estimate of UTC time resolved by the BDS is as follows:

s1, BDS time estimation based on GPS time service results:

s2, BDS time estimation based on the Glonass time service result:

s3, BDS time estimation based on the Galileo time service result:

s4.BDS time estimation optimal resultsComprises the following steps:

GPS time service result:

the UTC time estimate resolved by the GPS is as follows:

s1, GPS time estimation based on BDS time service results:

s2, GPS time estimation based on the Glonass time service result:

s3, GPS time estimation based on the Galileo time service result:

s4. optimal result of GPS time estimationComprises the following steps:

glonass timing results:

the Glonass solved UTC time estimate is as follows:

s1, estimating Glonass time based on a GPS time service result:

s2, estimating the Glonass time based on the BDS time service result:

s3, estimating the Glonass time based on the Galileo time service result:

s4.Glonass time estimation optimum resultComprises the following steps:

galileo timing results:

the estimates of UTC time obtained by Galileo solution are as follows:

s1, Galileo time estimation based on a GPS time service result:

s2, Galileo time estimation based on BDS time service results:

s3, Galileo time estimation based on the Glonass time service result:

s4.Galileo time estimation optimal resultComprises the following steps:

wherein: and a, b, c and d mark weight coefficients of UTC time resolved by each system, the value range is [0, 1], a + b + c + d is 1, a corresponds to a BDS time service result, b corresponds to the BDS time of the GPS time service result, c corresponds to the BDS time of the Glonass time service result, and d corresponds to the BDS time of the Galileo time service result.

A multisystem combined satellite navigation positioning time service device comprises:

the positioning and time service module is used for receiving satellite signals of the navigation systems, and the observed quantity of each navigation system is used for obtaining the position and UTC time of each navigation system through positioning calculation;

the time service position checking module checks positions mutually by using position confidence coefficient of positioning calculation to obtain optimal estimation of the position of the receiver and output an optimal estimation positioning result;

the time checking module is used for obtaining time deviation estimation among the UTC time of each navigation system through positioning calculation, calculating the UTC time estimation of a certain navigation system according to the time deviation estimation based on the time service result of each navigation system, and finally calculating the optimal estimation of the UTC time of the certain navigation system;

and the time service mode selection module is used for selecting a time service result appointed by the user according to the user configuration, outputting the time service result and outputting an optimal estimated time result.

The device is further improved in that:

the system also comprises an observed quantity gross error rejection module, wherein the observed quantity gross error rejection module is used for carrying out observed quantity gross error rejection processing on the received satellite signals and rejecting observation errors caused by observation noise interference and multipath interference.

A terminal device comprising a memory, a processor and a computer program stored in said memory and executable on said processor, said processor implementing the steps of the method as described above when executing said computer program.

A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method as described above.

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

according to the invention, each system can independently position and time service, so that the influence of single system/frequency point fault on the positioning/time service result can be effectively avoided; the combined positioning/time service has the advantages that the number of observation quantities is increased, and the defects that the faults of a single system/single frequency point cannot be effectively detected, so that the normal work of the terminal is guaranteed. The invention improves the joint positioning/time service into single system independent positioning/time service resolving, and utilizes the characteristic that the position of the terminal equipment is unchanged to carry out mutual check, thereby effectively detecting the fault of a single system/frequency point, and simultaneously carrying out filtering estimation on the difference value of the time service results of different systems to ensure that the terminal still normally works under the condition of the fault of the single system/frequency point.

Furthermore, in the calibration position working mode, the fault detection module is moved forward, and the observed quantity gross error is detected and eliminated before positioning/time service resolving, so that the time service precision can be further improved.

Drawings

In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a flow chart of the time service method of the present invention.

Fig. 2 is a schematic diagram of a time service device according to an embodiment of the invention.

Fig. 3 is a schematic diagram of a time service device according to another embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually arranged when the product of the present invention is used, the description is merely for convenience and simplicity, and the indication or suggestion that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, cannot be understood as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The invention is described in further detail below with reference to the accompanying drawings:

after the satellite navigation receiving terminal receives the GNSS signals, navigation messages and pseudo-range measurement values of the received satellites can be obtained, and therefore a pseudo-range observation equation set is constructed. The three-dimensional position information x, y, z of the receiver and the clock error delta t of the receiver are four unknowns of a pseudo-range observation equation set. The typical receiver adopts a least square method to realize the solution of a pseudo-range observation equation set, thereby obtaining the position and time information of the receiver and realizing the positioning and time service.

The positioning and time service performance based on satellite navigation is closely related to the crystal oscillator of the receiver, the algorithm of the time service module, the observation condition of the time service device and other factors. Meanwhile, under a certain part of timing application scenes, the timing terminal does not pay attention to the position information of the receiver, and only has strict requirements on the timing precision and reliability of the timing device.

In addition, Global Navigation Satellite System (GNSS) is composed of GPS in the united states, GLONASS in russia, BeiDou in china, and Galileo in the european union. The existence of a plurality of satellite navigation systems provides more options for the terminal to improve the time service reliability of the time service device.

The invention provides a method for independent calculation and mutual check of multiple systems, aiming at two different application scenes of positioning time service and independent time service, and realizing the optimization and improvement of the reliability of positioning and time service results by using the information uniquely determined by the position and time information of a receiver.

The principle of the invention is as follows:

in an application scene that the position of the time service device is not accurately calibrated, the time service device is separately positioned by adopting the observed quantity of each system, and the position of the time service device is unique, so that four pieces of position information obtained by the four systems through calculation can be checked with each other, and the position and time information with higher reliability can be obtained;

the accurate position of the time service device is obtained in a pre-calibration mode, each system rejects the satellite signal observed quantity with larger gross error according to the known position information by utilizing the accurate position of the time service device, and independently resolves the clock error of the receiver, so that the time service precision of the single system is improved;

under the condition that satellite signals of all systems are normally received, calculating difference values of receiver clock difference information obtained by independent calculation among all systems; when a certain system satellite signal observation quantity is interfered by factors such as interference, system faults, observation conditions and the like, the clock difference calculation error can be detected through the change of the difference value between the receiver clock difference calculated by the system and the receiver clock difference information calculated by other systems, so that the time service reliability of the time service device is effectively improved.

(1) Single system positioning time service basic principle

The pseudo-range observation equation is a basic equation of GNSS positioning/timing:

where ρ is⁽ⁿ⁾For the pseudorange, δ t, of satellite n_uFor receiver clock error, δ t⁽ⁿ⁾Correction of clock error for satellite n, I⁽ⁿ⁾Ionospheric delay, T, for satellite n⁽ⁿ⁾For the tropospheric delay of satellite n,the pseudorange observation noise for satellite n.

Delta t in pseudo-range observation equation (1)⁽ⁿ⁾、I⁽ⁿ⁾、T⁽ⁿ⁾It can be calculated from the navigation message and can be regarded as a known quantity. Thus, a corrected pseudorange observation may be defined as:

wherein r is⁽ⁿ⁾The geometric distance from the receiver u to the satellite n is (x, y, z) in the three-dimensional position of the receiver u, and the three-dimensional position of the satellite n at the transmitting time is (x)ⁿ，yⁿ，zⁿ) It can be expressed as:

the calculation formula of the pseudo range is as follows:

wherein the content of the first and second substances,is an estimate of the receiver time, tⁿAnd the tracking and synchronization of the satellite n are realized for the receiver, and the signal transmitting time is obtained after the synchronization.

At any time, when the receiver implements M pieces (M)>4) Receiving signals of a satellite to obtain M pseudo-range equations, and obtaining the three-dimensional position (x, y, z) of a receiver and the time t of the receiver by linearization of M nonlinear equations and least square solution_u. Wherein:

the output of the positioning time service result comprises a hardware interface and a software protocol interface. Typically, a 1pps hardware interface is provided on the receiver hardware, after the receiver realizes positioning calculation, the time service module controls the receiver to output the pulse per second at the whole second time of the UTC time, and meanwhile, a standard/self-defined software protocol (such as NMEA0183) is adopted to output the position and time information (such as a GPGGA statement) containing the receiver, so that the upper computer analyzes the software message, and the time and position information at the pulse per second time can be acquired.

The receiver realizes the signal reception of the GNSS through modules such as an antenna, radio frequency, baseband signal processing and the like, and each link can introduce certain delay in the whole link of the signal processing; moreover, for different receiver design schemes, the delay sizes are different, the delay needs to be calibrated, and the delay is considered when the receiver outputs 1pps second pulses, so that the pulse generation time of the receiver 1pps output end is guaranteed to be UTC whole second time.

(2) Multi-system positioning time service basic principle

In the GNSS joint positioning, because there are differences between different GNSS system times and group wave delay differences between different GNSS channels of the receiver, receiver clock differences of the systems need to be treated differently in the process of combining pseudorange observation equations of the systems together for positioning solution. This means that the number of positions in the pseudo-range observation equation set is increased, and in the single-system positioning time service resolving process, the unknown quantity contains (x, y, z, delta t)_u). In multi-system joint positioning, the unknowns become (x, y, z, δ t)_u1，δt_u2，…δt_uk) The number of unknowns becomes (k +3), where k is the number of systems participating in the positioning solution's observed quantity.

The satellite navigation system has independent system time, the solving of the formula (4) obtains receiver clock error information, and the receiver time at the receiving moment can be obtained through the formula (6), the obtained receiver time is the corresponding receiver time information of each system, the GPS, the BDS and the Galileo comprise the whole week number (WN, weeknumber) and the time of week (TOW, time of week), and the Glonass system comprises the number of days (DN, day number) and the time of day (TOD, time of day). Furthermore, the receiver can obtain the coordinated time correction parameters in different satellite systems from the text information broadcast by each system, and the UTC time of different satellite systems can be obtained by combining the receiver time information obtained in the formula (3). Due to group wave delay and differences of system time, the UTC time obtained by different systems through calculation often has certain deviation. As described in the basic principle of single system positioning time service, in the design process of the receiver, the influence of the delay at the receiver end on the time service can be eliminated through calibration and compensation. However, because the system time of different GNSS systems is maintained independently, there is a certain deviation in the UTC time calculated by different systems, and this deviation may change slowly with time.

As shown in fig. 1, an embodiment of the present invention discloses a multi-system joint satellite navigation positioning time service method, which includes the following steps:

s1 receiving satellite signals of four navigation systems including a GPS, a BDS, a Glonass and a Galileo, and obtaining position information and UTC time information of each navigation system by positioning and resolving the observed quantity of each navigation system;

s2, checking the position information with each other by using the position confidence coefficient of positioning calculation to obtain the optimal estimation of the receiver position;

the specific method for mutually checking the position information by using the position confidence coefficient of positioning calculation is as follows:

s1, initializing the position confidence coefficient of positioning calculation of each navigation system to 0;

s2, calculating the three-dimensional distance of each navigation system to obtain the position by positioning and resolving as follows:

PP_gb＝||P_gps-P_bds||

PP_gr＝||P_gps-P_glo||

PP_ge＝||P_gps-P_gal||

PP_br＝||P_bds-P_glo||

PP_be＝||P_bds-P_gal||

PP_re＝||P_glo-P_gal||

wherein, PP_ijThe position of the receiver obtained by the calculation of the GNSS system i and the position of the receiver obtained by the calculation of the GNSS system j are three-dimensional distances; the values of i, j are as follows: g represents GPS, b represents Beidou, r represents glonass, and e represents Galileo; p_gpsResolving position, P, for GPS_bdsResolving position, P, for BDS_gloResolving the position, P, for Glonass_galResolving the position for Galileo;

s3, calculating the reliability CL according to the three-dimensional distance of the positioning and resolving positions of two different systems_gb、CL_gr、CL_ge、CL_br、CL_beAnd CL_re；

Due to the uniqueness of the receiver position, the larger the three-dimensional distance is, the lower the consistency and the lower the reliability of the two positioning results are, otherwise, the smaller the three-dimensional distance is, the higher the consistency and the higher the reliability of the two positioning results are; the reliability value taking method can be obtained through engineering debugging. One embodiment is:

CL_ij＝1-PP_ij/max(PP_ij)

wherein, max (PP)_ij) Is the maximum of the magnitudes of all three-dimensional distances. Thus, CL_ijThe value range is [0, 1]]The larger the value is, the higher the reliability is.

S4, respectively calculating GPS resolving position P_gpsBDS resolving position P_bdsGlonass solved for position P_gloAnd Galileo solves the position P_galJoint confidence of (PCL)_gps、PCL_bds、PCL_glonassAnd PCL_galileo：

PCL_gps＝CL_gb+CL_gr+CL_ge

PCL_bds＝CL_gb+CL_br+CL_be

PCL_glonass＝CL_gr+CL_br+CL_re

PCL_galileo＝CL_ge+CL_be+CL_re

Wherein, PCL_gpsResolving position P for GPS_gpsJoint confidence of (2), PCL_bdsResolving position P for BDS_bdsJoint confidence of (2), PCL_gtonassResolving position P for Glonass_gloJoint confidence of (2), PCL_galileoResolving position P for Galileo_galJoint confidence of (3);

if PCL_gps< CLThreshold, adding PCL_gpsThe setting is 0, which indicates that the positioning result of the GPS navigation system has problems;

if PCL_bds< CLThreshold, adding PCL_bdsSetting the positioning result to be O, which indicates that the BDS navigation system has a problem in the positioning result;

if PCL_glonass< CLThreshold, adding PCL_glonassThe setting is 0, which indicates that the positioning result of the Glonass navigation system has problems;

if PCL_galileo< CLThreshold, adding PCL_galileoThe setting is 0, which indicates that the positioning result of the Galileo navigation system has a problem;

CLThreshold is a threshold value of comprehensive reliability of a positioning result, and an optimal value is obtained by engineering debugging.

S3, obtaining time deviation estimation between the UTC time of each navigation system through positioning calculation, calculating the UTC time estimation of a certain navigation system based on the time service result of each navigation system, and finally calculating the optimal estimation of the UTC time of the certain navigation system;

the calculation method of the time offset estimate is as follows:

and under the condition that the positioning credibility of the two systems meets the requirement, the receiver time checking module carries out filtering estimation on the difference value between the UTC time obtained by the calculation of each system. Taking the positioning time service of the GPS and BDS single system as an example, the receiver time (including week number weekno and second to in week) obtained by the GPS can be converted into UTC time through the conversion parameters of the GPS time and UTC time broadcasted in the GPS navigation message, and the UTC time is recorded as UTC time_gps(ii) a Similarly, UTC time UTC obtained by BDS system positioning time service calculation can be obtained_bds. The time obtained by each positioning calculation contains a measurement error, and therefore, the suppression of measurement noise can be realized by filtering the estimated value of the system time deviation at each calculation time. An exemplary embodiment is as follows:

time offset estimation TD between GPS time and BDS time_gb ^(k)Can be calculated from the following formula:

wherein, the value range of alpha is [0, 1], which is a common implementation mode of a simple low-pass filter in engineering, and when alpha is 1, the output of the filter is the measured value at the current resolving moment; a smaller a means a better noise performance.

Similarly, solving for time i, the time offset between GPS and Glonass is estimated as TD_gr ^(k)The time offset between GPS and Galileo is estimated as TD_ge ^(k)。

The specific method for calculating the optimal estimate of UTC time is as follows:

taking the BDS time service result as an example, the UTC time estimation processing procedure obtained by the BDS calculation is as follows:

s1, BDS time estimation based on GPS time service results:

s2, BDS time estimation based on the Glonass time service result:

s3, BDS time estimation based on the Galileo time service result:

s4, the optimal result of BDS time estimation is as follows:

wherein: and a, b, c and d mark weight coefficients of the UTC time resolved by each system, the value range is [0, 1], and a + b + c + d is 1. At different moments, the number of satellites and the like participating in positioning calculation of each system is different, factors influencing positioning/time service precision can be comprehensively considered in engineering realization, and a self-adaptive optimal value is obtained through debugging.

It should be noted that, in the above example, if a positioning failure of one system or the positioning result confidence is 0, the weight coefficient of the UTC system corresponding to the system in S4 is set to 0.

S4 selects the time service result appointed by the user and outputs the result according to the user configuration.

As shown in fig. 3, in another embodiment of the present invention, after receiving satellite signals of four navigation systems, i.e., GPS, BDS, Glonass, and Galileo, the observation gross error rejection processing is performed on the received satellite signals, so as to reject observation errors caused by observation noise interference and multipath interference. The specific method for removing the observed quantity gross error of the received satellite signals is as follows:

according to the historical information of the receiver position estimation, the sum of the pseudo-range measurement value of the corresponding satellite minus the geometric distance predicted value and the receiver clock error predicted value can be calculated, and the difference between the measured value and the predicted value is pseudo-range residual error. The pseudorange residuals are related on the one hand to the accuracy of the receiver position and on the other hand to the predicted value of the clock error. Therefore, the pseudorange residuals of different satellites often include two parts of error information of the receiver clock error, and the accuracy of the receiver position information is high due to the historical position information and the inertia law, so the pseudorange residuals of different satellites tend to be consistent. Gross error rejection of observed quantities assumes that pseudorange measurements for a majority of satellites are reliable, and therefore gross errors can be identified and rejected in a "clustering" manner.

Referring to fig. 2, an embodiment of the present invention discloses a multi-system combined satellite navigation positioning time service apparatus, including:

the positioning and time service module is used for receiving satellite signals of four navigation systems including a GPS (global positioning system), a BDS (brain navigation system), a Glonass and a Galileo, and the observed quantity of each navigation system is used for obtaining the position information and the UTC (universal time coordinated) time information of each navigation system through positioning and resolving;

the positioning time service module realizes satellite signal reception of four systems of GPS, BDS, Glonass and Galileo, the observed quantity of each system is independently positioned and resolved by the positioning time service module, thereby four different pieces of position and time information can be obtained and are respectively marked as P_gps,P_bds,P_glo,P_galAndas described in section 3 of this document, the delay of the receiver for the navigation signals of different frequencies of different systems can be obtained by factory calibration, and the delay compensation module shown in fig. 2 performs the estimated UTC time advanceThe line delay compensation is carried out, namely the UTC time UTC obtained by resolving each system after the compensation can be obtained_gps,UTC_bds,UTC_glo,UTC_gal. The UTC time is a unified time standard, so the UTC time obtained by measurement and calculation of four different GNSS system observations is theoretically consistent, and only includes errors existing in each system time and errors caused by positioning time service calculation.

The time service position checking module checks the position information by using the position confidence coefficient of positioning calculation to obtain the optimal estimation of the position of the receiver;

since the receiver location information is unique. In this way, the receiver position information P obtained by resolving each system through the position checking module_gps,P_bds,P_glo,P_galAnd performing mutual check to obtain the optimal estimation of the position of the receiver, and simultaneously transmitting inaccurate position information to a receiver time check module.

The time checking module is used for obtaining time deviation estimation among the UTC time of each navigation system through positioning calculation, calculating the UTC time estimation of a certain navigation system based on the time service result of each navigation system, and finally calculating the optimal estimation of the UTC time of the certain navigation system;

and the receiver time checking module receives the four UTC time information from each system positioning time service module and the confidence coefficient of each system positioning precision and outputs the optimal estimation of the UTC time obtained by the calculation of each system.

And the time service mode selection module is used for selecting a time service result appointed by the user according to the user configuration and outputting the time service result.

Referring to fig. 3, another embodiment of the invention discloses a multi-system combined satellite navigation positioning time service device, which is additionally provided with an observed quantity gross error rejection module based on a calibration position. The observed quantity gross error rejection module reduces the unknown quantity of the positioning time service module from 4 to 1, and provides a theoretical basis for detecting and rejecting the observation errors caused by the interference such as observation noise, multipath and the like; after gross error rejection is finished, the time service precision is optimized and improved.

In the case where the nominal position is known, the pseudorange observation equation of equation (2) may be further expressed as:

wherein the content of the first and second substances,an estimate of the receiver clock error obtained for satellite n; in the case where a system acquires multiple satellite observation equations, multiple receiver clock error estimates can be obtained. All satellites adopt one receiver time to calculate pseudo ranges, so that only one actual value of the receiver clock difference is provided, and the observed quantity gross error removing module removes the satellites with larger gross errors by using the actual value, thereby realizing the improvement of time service precision.

The elimination of gross errors provides a theoretical basis for the improvement of time service precision, and simultaneously, the receiver clock errors of all observation satellites in the system are the same, so that the precondition can still be the basis of single system time service reliability judgment and the measurement of precision. The standard deviation estimated by the clock deviation of different satellite receivers at any resolving moment can be used as a basis for measuring the time service reliability, and when the standard deviation exceeds a certain threshold value (obtained by debugging according to engineering practice and theoretical basis), the time service result of the system is considered to be invalid.

The embodiment of the invention discloses terminal equipment, which comprises a memory, a processor and a computer program which is stored in the memory and can run on the processor, wherein the steps of the method are realized when the processor executes the computer program.

The embodiment of the invention provides terminal equipment. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. The processor realizes the steps of the above-mentioned method embodiments when executing the computer program. Alternatively, the processor implements the functions of the modules/units in the above device embodiments when executing the computer program.

The computer program may be partitioned into one or more modules/units that are stored in the memory and executed by the processor to implement the invention.

The terminal device can be a desktop computer, a notebook, a palm computer, a cloud server and other computing devices. The terminal device may include, but is not limited to, a processor, a memory.

The processor may be a Central Processing Unit (CPU), other general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, etc.

The memory may be used for storing the computer programs and/or modules, and the processor may implement various functions of the terminal device by executing or executing the computer programs and/or modules stored in the memory and calling data stored in the memory.

The embodiment of the invention discloses a computer readable storage medium, which stores a computer program, and the computer program realizes the steps of the method when being executed by a processor.

The terminal device integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer memory, Read-only memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, etc. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.