Time-frequency remote calibration method

Abstract

The embodiment of the invention discloses a time-frequency remote calibration method. The method comprises the following steps: analyzing a Beidou satellite navigation signal by using a base station to obtain a first combined pseudo-range observation value and a first combined carrier phase observation value corresponding to each visual satellite, and analyzing the Beidou satellite navigation signal by using a calibration station to obtain a second combined pseudo-range observation value and a second combined carrier phase observation value corresponding to each visual satellite; establishing a first observation equation mathematical model and a second observation equation mathematical model; performing mathematical processing on the first observation equation mathematical model to obtain a first observation equation, and performing mathematical processing on the second observation equation mathematical model to obtain a second observation equation; obtaining a receiver clock difference of the base station according to the first observation equation, obtaining a receiver clock difference of the calibration station according to the second observation equation, and obtaining an inter-station comparison time difference; and calculating the time measurement uncertainty corresponding to the inter-station comparison time difference and completing the calibration of the calibration station by the reference station.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of time and frequency. More particularly, it relates to a time and frequency remote calibration method. BACKGROUND

[0002] With the continuous development of time and frequency technology, time and frequency devices are widely used in various industries. With the increase of service time, time and frequency devices will inevitably age, resulting in a decrease in their performance indicators, such as time synchronization accuracy, frequency stability, phase noise, and the like. In order to ensure that the time and frequency characteristics and technical indicators of time and frequency devices are within the normal range and meet the actual application needs of users, it is necessary to periodically or routinely calibrate them to avoid a decrease in the performance of the entire system due to the decrease in the indicator of a device or some devices.

[0003] Time and frequency device calibration is usually performed by sending the device to be calibrated to a third-party metrological detection agency, and a corresponding calibration certificate is issued after the calibration is completed. This method requires the device to be calibrated to be disassembled from the system, transported to the metrological detection agency for calibration, and then reconnected to the system for continuous operation after the calibration. This process may take several days to several weeks, during which the system may not operate normally.

[0004] In addition, China's Beidou-3 system has officially released the public service signal B2b and the precise point positioning service signal PPP-B2b interface control file. The PPP-B2b signal is broadcast in real time by the Beidou-3 GEO satellite in China and surrounding areas. The navigation message broadcast by the PPP-B2b signal contains the orbit correction number and the clock difference correction number of the Beidou satellite.

[0005] For some important time and frequency systems, continuous operation is often required, and the time and frequency devices in the system are not convenient to disassemble and may even not be able to operate independently, so they do not have the conditions to be sent to a third-party metrological detection agency for metrological calibration, and the traditional metrological detection method cannot be used to detect the time and frequency characteristics. SUMMARY

[0006] The present application aims to provide a time and frequency remote calibration method to solve at least one of the problems in the prior art.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solution:

[0008] The present application provides a time and frequency remote calibration method in the first aspect, which comprises:

[0009] The first combined pseudo-range observation value and the first combined carrier phase observation value corresponding to each visible satellite are obtained by analyzing the Beidou satellite navigation signal using the reference station, and the second combined pseudo-range observation value and the second combined carrier phase observation value corresponding to each visible satellite are obtained by analyzing the Beidou satellite navigation signal using the calibration station.

[0010] Establishing a first observation equation mathematical model using the first combined pseudorange observation value and the first combined carrier phase observation value, and establishing a second observation equation mathematical model using the second combined pseudorange observation value and the second combined carrier phase observation value;

[0011] Performing mathematical processing on the first observation equation mathematical model to obtain a first observation equation, and performing mathematical processing on the second observation equation mathematical model to obtain a second observation equation;

[0012] Obtaining a receiver clock bias of the reference station according to the first observation equation, and obtaining a receiver clock bias of the calibration station according to the second observation equation;

[0013] Obtaining an inter-station comparison time difference according to the receiver clock difference of the reference station and the receiver clock difference of the calibration station;

[0014] The time measurement uncertainty corresponding to the inter-station comparison time difference is calculated and the calibration of the reference station to the calibration station is completed.

[0015] Optionally, the obtaining of a first combined pseudorange observation value and a first combined carrier phase observation value corresponding to each visible satellite by parsing the Beidou satellite navigation signal using the reference station includes:

[0016]

[0017] Where, P IF is the first combined pseudorange observation value; Φ IF is the first combined carrier phase observation value; P1 is the first data obtained based on the observation data; P2 is the second data obtained based on the observation data; L1 is the third data obtained based on the observation data; L2 is the fourth data obtained based on the observation data; f1 is the frequency corresponding to P1 and L1; f2 is the frequency corresponding to P2 and L2;

[0018] The method of using the calibration station to analyze the Beidou satellite navigation signal to obtain a second combined pseudorange observation value and a second combined carrier phase observation value corresponding to each visible satellite includes:

[0019]

[0020] Where, P IF1 is the second combined pseudorange observation value; Φ IF1 is the second combined carrier phase observation value; P 11 is the fifth data obtained based on the observation data; 12 is the sixth data obtained based on the observation data; L 11 is the seventh data obtained based on the observation data; L 12 is the eighth data obtained based on the observation data; f11 P 11 and L 11 corresponding frequency; f 12 P 12 and L 12 corresponding frequency.

[0021] Optionally, the method further comprises:

[0022] obtaining a maximum value of inter-station comparison time difference;

[0023] obtaining a difference value according to the maximum value of inter-station comparison time difference and a preset average value of inter-station comparison time difference;

[0024] judging whether the time measurement uncertainty is reasonable according to the difference value and the time measurement uncertainty;

[0025] if the time measurement uncertainty is greater than the difference value, the time measurement uncertainty is reasonable.

[0026] Optionally, the first observation equation mathematical model comprises a first sub-observation equation mathematical model and a second sub-observation equation mathematical model.

[0027] The first observation equation mathematical model is established by using the first combined pseudo-range observation value and the first combined carrier phase observation value, and comprises:

[0028] The first sub-observation equation mathematical model is established by using the first combined pseudo-range observation value, and is:

[0029] P IF = ρ + c (dt - dT) + T + d m

[0030] In the formula, P IF is a first combined pseudo-range observation value; ρ is a satellite-to-ground geometric distance of a reference station, (x u , y u , z u ) is a receiver position of the reference station, (x s , y s , z s ) is a satellite position of the reference station; c is a light speed; dt is a receiver clock error of the reference station; dT is a satellite clock error of the reference station; T is a troposphere delay error of the reference station; d m is a multipath effect corresponding to the first combined pseudo-range observation value.

[0031] The second sub-observation equation mathematical model is established by using the first combined carrier phase observation value, and is:

[0032] Φ IF = ρ + c (dt - dT) + T + N IF+ δ m

[0033] wherein, Φ IF is the first combined carrier phase observation; N IF is the first integer ambiguity; δ m is the multipath effect corresponding to the first combined carrier phase observation.

[0034] Optionally, the second observation equation mathematical model comprises a third sub-observation equation mathematical model and a fourth sub-observation equation mathematical model.

[0035] The step of establishing the second observation equation mathematical model by using the second combined pseudo-range observation and the second combined carrier phase observation comprises:

[0036] The step of establishing the third sub-observation equation mathematical model by using the second combined pseudo-range observation is:

[0037] P IF1 = ρ1+ c (dt1- dT1) + T1+ d m1

[0038] wherein, P IF1 is the second combined pseudo-range observation; ρ1is the geometric distance from the calibration station to the satellite, (x u1 ,y u1 ,z u1 ) is the receiver position of the calibration station, (x1 s ,y1 s ,z1 s ) is the satellite position of the calibration station; c is the speed of light; dt1is the receiver clock error of the calibration station; dT1is the satellite clock error of the calibration station; T1is the tropospheric delay error of the calibration station; d m1 is the multipath effect corresponding to the second combined pseudo-range observation;

[0039] The step of establishing the fourth sub-observation equation mathematical model by using the second combined carrier phase observation is:

[0040] Φ IF1 = ρ1+ c (dt1- dT1) + T1+ N IF1 + δ m1

[0041] wherein, Φ IF1 is the second combined carrier phase observation; N IF1 is the second integer ambiguity; δ m1 is the multipath effect corresponding to the second combined carrier phase observation.

[0042] Optionally, the step of performing mathematical processing on the first observation equation mathematical model comprises:

[0043] Cycle slip detection and repair is performed on the first combined carrier phase observations in the first observation equation mathematical model;

[0044] Error correction is performed on the satellite positions and satellite clock corrections of the reference stations in the first observation equation mathematical model;

[0045] Parameter estimation is performed on the first integer ambiguity, the receiver positions of the reference stations, the receiver clock corrections of the reference stations and the tropospheric delay errors of the reference stations in the first observation equation mathematical model.

[0046] Optionally, the mathematical processing of the second observation equation mathematical model comprises:

[0047] Cycle slip detection and repair is performed on the second combined carrier phase observations in the second observation equation mathematical model;

[0048] Error correction is performed on the satellite positions and satellite clock corrections of the calibration stations in the second observation equation mathematical model;

[0049] Parameter estimation is performed on the second integer ambiguity, the receiver positions of the calibration stations, the receiver clock corrections of the calibration stations and the tropospheric delay errors of the calibration stations in the second observation equation mathematical model.

[0050] Optionally, the inter-station comparison time difference is obtained according to the receiver clock corrections of the reference stations and the receiver clock corrections of the calibration stations, and comprises:

[0051] dt-dt1=(T A -T BDT )-(T B -T BDT )=T A -T B

[0052] In the formula, T A is the local time of the reference station; T B is the local time of the calibration station; and T BDT is the Beidou system time.

[0053] Optionally, the formula for calculating the time measurement uncertainty corresponding to the inter-station comparison time difference is:

[0054] U=ku c

[0055] In the formula, k is a containing factor; and u c is a time measurement combined uncertainty.

[0056] Optionally, the formula for calculating the time measurement combined uncertainty is:

[0057]

[0058] In the formula, u A is the standard deviation of the comparison time difference between stations; u B1 is the uncertainty introduced by the calibration device of the reference station and the calibration device of the calibration station; u B2 is the uncertainty introduced by the signal propagation path; u B3 is the uncertainty introduced by the satellite end; u B4 is the uncertainty introduced by the temperature; u B5 is the uncertainty introduced by the equipment calibration residual.

[0059] The beneficial effects of the present application are as follows:

[0060] The technical solution of the present application can be used for remote calibration of time-frequency equipment which is inconvenient to disassemble or cannot be independently operated, so as to ensure the reliability of time-frequency application, provide high-precision metrological calibration service, and reduce the influence of Beidou broadcast ephemeris on time difference solution result, thereby improving the calibration precision of time-frequency equipment. BRIEF DESCRIPTION OF DRAWINGS

[0061] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0062] Figure 1 A flowchart of a time-frequency remote calibration method provided by an embodiment of the present application is shown.

[0063] Figure 2 A flowchart of a time-frequency remote calibration method provided by another embodiment of the present application is shown.

[0064] Figure 3 A schematic diagram of a time-frequency remote calibration system provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0065] In order to more clearly illustrate the present application, the present application will be further described below with reference to the embodiments and the accompanying drawings. Like components are denoted by the same reference numerals in the drawings. Those skilled in the art should understand that the specific description below is illustrative rather than limiting, and should not limit the protection scope of the present application.

[0066] For some important time-frequency systems, continuous operation is often required, the time-frequency equipment in the system is inconvenient to disassemble, or even cannot be independently operated, and does not have the condition of being sent to a third-party metrological detection institution for metrological calibration, and cannot use the traditional metrological detection method to perform metrological detection on the time-frequency characteristics.

[0067] In view of this, as Figure 1As shown, one embodiment of the application provides a time-frequency remote calibration method, which comprises: using a reference station to analyze Beidou satellite navigation signals to obtain a first combined pseudorange observation value and a first combined carrier phase observation value corresponding to each visible satellite, and using a calibration station to analyze Beidou satellite navigation signals to obtain a second combined pseudorange observation value and a second combined carrier phase observation value corresponding to each visible satellite; using the first combined pseudorange observation value and the first combined carrier phase observation value to establish a first observation equation mathematical model, and using the second combined pseudorange observation value and the second combined carrier phase observation value to establish a second observation equation mathematical model; performing mathematical processing on the first observation equation mathematical model to obtain a first observation equation, and performing mathematical processing on the second observation equation mathematical model to obtain a second observation equation; obtaining a receiver clock bias of the reference station according to the first observation equation, and obtaining a receiver clock bias of the calibration station according to the second observation equation; obtaining an inter-station comparison time difference according to the receiver clock bias of the reference station and the receiver clock bias of the calibration station; and calculating a time measurement uncertainty corresponding to the inter-station comparison time difference and completing calibration of the calibration station by the reference station.

[0068] In one specific example, based on the PPP-B2b signal broadcast by the Beidou No. 3 GEO satellite, first, the Beidou satellite navigation signal is collected by a high-precision time-frequency remote calibration device, the navigation message frame structure is analyzed, and carrier phase measurement values and other data are obtained; then, after the processes of cycle slip detection and repair, error correction, parameter estimation, and data exchange, a high-precision inter-station comparison time difference is calculated and obtained; finally, the time measurement uncertainty is evaluated according to the inter-station comparison time difference, and the rationality of the uncertainty evaluation result is verified by using higher-precision inter-station comparison means to measure data.

[0069] In one specific example, based on the high-precision time-frequency remote calibration process of the Beidou PPP-B2b service, first, a calibration system is built, Beidou satellite navigation signals are collected, navigation messages are analyzed, carrier phase observation values, pseudocode observation values, broadcast ephemeris, and other data are obtained, an observation equation mathematical model is established, and after the data processing processes of cycle slip detection and repair, error correction, and parameter estimation, the local clock bias is solved; then, the clock bias is exchanged between two stations, and the inter-station comparison time difference is calculated; finally, the uncertainty is evaluated and verified.

[0070] The embodiment can be used for remote calibration of time-frequency devices that are not convenient to disassemble or cannot operate independently, to ensure the reliability of time-frequency applications, provide high-precision metrological calibration services, and reduce the influence of Beidou broadcast ephemeris on the time difference solution result, thereby improving the calibration precision of time-frequency devices.

[0071] In one specific example, as shown in Figure 2 the calibration system is built, and Beidou satellite navigation signals are collected.

[0072] Further, as shown in Figure 3 The calibration system is built, and a set of high-precision time-frequency remote calibration devices, GNSS antennas and Beidou short message antennas are respectively erected at the reference station and the calibration station. A local time-frequency source and the device to be calibrated respectively provide 1PPS time signals and 10MHz frequency signals for the calibration devices of the two stations; the GNSS antenna is used to receive satellite navigation signals and needs to be erected on the roof without any obstruction around to ensure normal reception of navigation signals; the Beidou short message antenna is used to realize data exchange and needs to be equipped with a Beidou system authorized two-way SIM card and erected outdoors without obstruction on the south side to ensure normal communication. When the Beidou short message antenna is erected at a position far from the indoor calibration device, a serial port server can be erected to complete data communication.

[0073] Further, after the calibration system is built, all devices are powered on and start to collect Beidou satellite navigation signals.

[0074] In a specific example, the Beidou navigation message is parsed.

[0075] Further, after the high-precision time-frequency remote calibration device normally receives the satellite navigation signal, it automatically parses the data according to the frame structure of the navigation message to obtain the pseudo-range observation value, carrier phase observation value and broadcast ephemeris corresponding to each visible satellite, and the Beidou orbit correction number and clock correction number are parsed from the navigation message of the PPP-B2b signal.

[0076] Further, during the parsing process of the navigation message of the PPP-B2b signal, attention should be paid to the matching of different information types. The Beidou orbit correction number is broadcast in the information type 2 message, and the clock correction number is broadcast in the information type 4 message. The prerequisite for matching the use of information type 2 and information type 4 is that there are the same IOD SSR field and IOD Corr field. The Beidou broadcast ephemeris and the PPP-B2b signal are matched through the IODN in the information type 2 and the IODC in the B1C signal broadcast ephemeris.

[0077] In a possible implementation, the step of parsing the Beidou satellite navigation signal by using the reference station to obtain the first combined pseudo-range observation value and the first combined carrier phase observation value corresponding to each visible satellite includes:

[0078]

[0079] In the formula, P IF is the first combined pseudo-range observation value; Φ IFP1 is the first data obtained according to the observation data; P2 is the second data obtained according to the observation data; L1 is the third data obtained according to the observation data; L2 is the fourth data obtained according to the observation data; f1 is the frequency corresponding to P1 and L1; f2 is the frequency corresponding to P2 and L2;

[0080] The second combined pseudo-range observation value and the second combined carrier phase observation value corresponding to each visible satellite obtained by resolving the Beidou satellite navigation signal by using the calibration station include:

[0081]

[0082] P IF1 is the second combined pseudo-range observation value; Φ IF1 is the second combined carrier phase observation value; P 11 is the fifth data obtained according to the observation data; P 12 is the sixth data obtained according to the observation data; L 11 is the seventh data obtained according to the observation data; L 12 is the eighth data obtained according to the observation data; f 11 is the frequency corresponding to P 11 and L 11 ; f 12 is the frequency corresponding to P 12 and L 12 .

[0083] In a possible implementation, the first observation equation mathematical model includes a first sub-observation equation mathematical model and a second sub-observation equation mathematical model;

[0084] The first observation equation mathematical model is established by using the first combined pseudo-range observation value and the first combined carrier phase observation value, and includes:

[0085] The first sub-observation equation mathematical model is established by using the first combined pseudo-range observation value, and is as follows:

[0086] P IF = ρ + c (dt - dT) + T + d m

[0087] P IF is the first combined pseudo-range observation value; ρ is the geometric distance from the reference station to the satellite, (x u , y u , z u ) is the receiver position of the reference station, (x s , y s , z s) is a satellite position of the reference station; c is a light speed; dt is a receiver clock error of the reference station; dT is a satellite clock error of the reference station; T is a troposphere delay error of the reference station; d m is a multipath effect corresponding to the first combined pseudo-range observation value;

[0088] A second sub-observation equation mathematical model is established by using the first combined carrier phase observation value, and is as follows:

[0089] Φ IF = p + c (dt - dT) + T + N IF + δ m

[0090] In the formula, Φ IF is the first combined carrier phase observation value; N IF is a first integer ambiguity; and δ m is a multipath effect corresponding to the first combined carrier phase observation value.

[0091] In a possible implementation, the second observation equation mathematical model comprises a third sub-observation equation mathematical model and a fourth sub-observation equation mathematical model.

[0092] The second observation equation mathematical model is established by using the second combined pseudo-range observation value and the second combined carrier phase observation value, and comprises:

[0093] A third sub-observation equation mathematical model is established by using the second combined pseudo-range observation value, and is as follows:

[0094] P IF1 = p1 + c (dt1 - dT1) + T1 + d m1

[0095] In the formula, P IF1 is the second combined pseudo-range observation value; p1 is a satellite-ground geometric distance of the calibration station, (x u1 ,y u1 ,z u1 ) is a receiver position of the calibration station, (x1 s ,y1 s ,z1 s ) is a satellite position of the calibration station; c is a light speed; dt1 is a receiver clock error of the calibration station; dT1 is a satellite clock error of the calibration station; T1 is a troposphere delay error of the calibration station; d m1 is a multipath effect corresponding to the second combined pseudo-range observation value;

[0096] A fourth sub-observation equation mathematical model is established by using the second combined carrier phase observation value, and is as follows:

[0097] Φ IF1=ρ1+c(dt1-dT1)+T1+N IF1 +δ m1

[0098] Where, Φ IF1 is the second combined carrier phase observation value; N IF1 is the second full cycle ambiguity; δ m1 is the multipath effect corresponding to the second combined carrier phase observation value.

[0099] In a specific example, a mathematical model is established. Further, after completing the Beidou navigation message parsing, the observation equation mathematical model is established using the pseudo code observation value and the carrier phase observation value.

[0100] Furthermore, for the base station, assuming there are n visible satellites, for a certain visible satellite, we have:

[0101] P IF =ρ+c(dt-dT)+T+d m

[0102] Φ IF =ρ+c(dt-dT)+T+N IF +δ m

[0103] Where, P IF , Φ IF are the first combined pseudorange observation value and the first combined carrier phase observation value obtained by the dual-frequency ionosphere-free combination; ρ is the satellite-to-ground geometric distance of the reference station, (x u ,y u ,z u ) is the receiver position of the reference station, (x s ,y s ,z s ) is the satellite position of the reference station; c is the speed of light; dt is the receiver clock error of the reference station; dT is the satellite clock error of the reference station; T is the tropospheric delay error of the reference station; N IF is the integer ambiguity of the reference station; d m , δ m are the multipath effects corresponding to the first combined pseudorange observation value and the first combined carrier phase observation value respectively.

[0104] Furthermore, for the calibration station, assuming there are n visible satellites, for a certain visible satellite, we have:

[0105] P IF1 =ρ1+c(dt1-dT1)+T1+d m1

[0106] Φ IF1= ρ1 + c (dt1 - dT1) + T1 + N IF1 + δ m1

[0107] wherein P IF1 , Φ IF1 are the second combined pseudo-range observation value and the second combined carrier phase observation value obtained by using the dual-frequency ionosphere-free combination; ρ1 is the geometric distance from the calibration station to the satellite, (x u1 , y u1 , z u1 ) is the receiver position of the calibration station, (x1 s , y1 s , z1 s ) is the satellite position of the calibration station; c is the speed of light; dt1 is the receiver clock error of the calibration station; dT1 is the satellite clock error of the calibration station; T1 is the tropospheric delay error of the calibration station; N IF1 is the integer ambiguity of the calibration station; d m1 , δ m1 are the multipath effects corresponding to the second combined pseudo-range observation value and the second combined carrier phase observation value respectively.

[0108] In a possible implementation, the mathematical processing of the first observation equation mathematical model comprises: cycle slip detection and repair of the first combined carrier phase observation value in the first observation equation mathematical model; error correction of the satellite position and the satellite clock error of the reference station in the first observation equation mathematical model; parameter estimation of the first integer ambiguity, the receiver position of the reference station, the receiver clock error of the reference station and the tropospheric delay error of the reference station in the first observation equation mathematical model.

[0109] In a possible implementation, the mathematical processing of the second observation equation mathematical model comprises: cycle slip detection and repair of the second combined carrier phase observation value in the second observation equation mathematical model; error correction of the satellite position and the satellite clock error of the calibration station in the second observation equation mathematical model; parameter estimation of the second integer ambiguity, the receiver position of the calibration station, the receiver clock error of the calibration station and the tropospheric delay error of the calibration station in the second observation equation mathematical model.

[0110] In a specific example, data processing is performed.

[0111] Further, a series of data processing is performed on the carrier phase observation value, the pseudo-code observation value and the like, including cycle slip detection and repair, error correction and parameter estimation.

[0112] Furthermore, cycle slip detection and repair: a real-time carrier phase cycle slip detection and repair method is used to detect and repair cycle slips according to the cycle slip feature classification.

[0113] Furthermore, error correction: The error terms that need to be considered in the time difference solution process mainly include errors related to the satellite, errors related to the signal propagation path, and errors related to the calibration device.

[0114] Furthermore, for satellite-related errors, the orbit correction and clock correction obtained by analyzing the PPP-B2b signal are compared with the (x s ,y s ,z s ) and dT, it is necessary to pay attention to the update cycle of orbit correction and clock correction to judge their effectiveness.

[0115] Furthermore, for other error terms, if there is a mature high-precision correction model, the existing correction model is directly adopted, such as: relativistic effect, ionospheric delay error, and tropospheric delay dry component; if not, the additional parameter method is used for calculation and correction.

[0116] Further, parameter estimation: using the least squares estimation method, the whole cycle ambiguity N IF , receiver position (x u ,y u ,z u ), receiver clock error dt, and the wet component of tropospheric delay T are taken as parameters to be estimated, and pseudorange observations and carrier phase observations are used to estimate the parameters to be estimated.

[0117] In a possible implementation, obtaining the inter-station comparison time difference according to the receiver clock difference of the reference station and the receiver clock difference of the calibration station includes:

[0118] dt-dt1=(T A -T BDT )-(T B -T BDT )=T A -T B

[0119] Where, T A is the local time of the base station; T B is the local time of the calibration station; T BDT This is the Beidou system time.

[0120] In a specific example, the time difference between stations is calculated.

[0121] Further, through the carrier phase cycle slip detection and repair, main error correction, additional parameter estimation and other processes, the local time and the time difference of BDT can be calculated, and the results are respectively recorded as:

[0122] dt = ΔT A = T A -T BDT

[0123] dt1 = ΔT B = T B -T BDT

[0124] Further, then the two stations complete the local time difference exchange through the network or the Beidou short message service, align the epoch difference, and calculate the inter-station comparison time difference:

[0125] dt-dt1 = ΔT AB = (T A -T BDT )-(T B -T BDT )= T A -T B

[0126] Further, the cable and antenna cable time delay of the 1PPS time signal of the two stations need to be measured and recorded in advance, and are deducted in the comparison time difference result.

[0127] In a possible implementation, a formula for calculating a time measurement uncertainty corresponding to the inter-station comparison time difference is:

[0128] U = ku c

[0129] In the formula, k is a containing factor; u c is a time measurement combined uncertainty.

[0130] In a possible implementation, a formula for calculating the time measurement combined uncertainty is:

[0131]

[0132] In the formula, u A is a standard deviation statistical value of the inter-station comparison time difference; u B1 is an uncertainty introduced by the calibration device of the reference station and the calibration device of the calibration station; u B2 is an uncertainty introduced by a signal propagation path; u B3 is an uncertainty introduced by a satellite end; u B4 is an uncertainty introduced by temperature; and u B5 is an uncertainty introduced by equipment calibration residual error.

[0133] In a possible implementation, the method further comprises: obtaining a maximum value of the inter-station comparison time difference; obtaining a difference value according to the maximum value of the inter-station comparison time difference and a preset average value of the inter-station comparison time difference; determining whether the time measurement uncertainty is reasonable according to the difference value and the time measurement uncertainty; and if the time measurement uncertainty is greater than the difference value, the time measurement uncertainty is reasonable.

[0134] In a specific example, the uncertainty evaluation and verification are performed.

[0135] Further, the uncertainty evaluation is performed by using the inter-station comparison time difference data, and the higher-precision inter-station time difference measurement data between two stations is used as a reference to verify the rationality of the uncertainty evaluation result.

[0136] Further, the time measurement uncertainty is evaluated as follows:

[0137] Further, the time measurement combined uncertainty is:

[0138]

[0139] In the formula, u A is a std statistical value of the inter-station comparison time difference ΔT AB , u B1 , u B2 , u B3 , u B4 , and u B5 are uncertainties introduced by a calibration device, a signal propagation path, a satellite end, temperature, and equipment calibration residual error, respectively.

[0140] Further, the time measurement uncertainty is: U = ku c .

[0141] Further, the time measurement uncertainty verification is as follows:

[0142] Further, a maximum value of the inter-station time difference is calculated by using the measured actual calibration data, and is denoted as ΔT AB_max ; an average value of the inter-station time difference is calculated according to the satellite two-way comparison data, and is denoted as ΔT AB_TW , and a difference value is denoted as δt = ΔT AB_max - ΔT AB_TW .

[0143] Further, if δt < U, it is indicated that the above-mentioned time measurement uncertainty evaluation is reasonable.

[0144] In the description of the present application, it needs to be explained that the terms "upper", "lower" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0145] It also needs to be explained that in the description of the present application, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or equipment. Without more limitation, the element defined by the sentence "including a…" does not exclude the presence of other identical elements in the process, method, article or equipment including the element.

[0146] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not a limitation on the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A time-frequency remote calibration method, characterized in that: The method includes: The base station is used to parse the BeiDou satellite navigation signal to obtain a first combined pseudorange observation value and a first combined carrier phase observation value corresponding to each visible satellite. The calibration station is used to parse the BeiDou satellite navigation signal to obtain a second combined pseudorange observation value and a second combined carrier phase observation value corresponding to each visible satellite. Establishing a first observation equation mathematical model using the first combined pseudorange observation value and the first combined carrier phase observation value, and establishing a second observation equation mathematical model using the second combined pseudorange observation value and the second combined carrier phase observation value; Performing mathematical processing on the first observation equation mathematical model to obtain a first observation equation, and performing mathematical processing on the second observation equation mathematical model to obtain a second observation equation; Obtaining a receiver clock bias of the reference station according to the first observation equation, and obtaining a receiver clock bias of the calibration station according to the second observation equation; Obtaining an inter-station comparison time difference according to the receiver clock difference of the reference station and the receiver clock difference of the calibration station; The time measurement uncertainty corresponding to the inter-station comparison time difference is calculated and the calibration of the reference station to the calibration station is completed.

2. The time-frequency remote calibration method according to claim 1, characterized in that: The method of using the reference station to analyze the Beidou satellite navigation signal to obtain a first combined pseudorange observation value and a first combined carrier phase observation value corresponding to each visible satellite includes: Where, P IF is the first combined pseudorange observation value; Φ IF is the first combined carrier phase observation value; P1 is the first data obtained based on the observation data; P2 is the second data obtained based on the observation data; L1 is the third data obtained based on the observation data; L2 is the fourth data obtained based on the observation data; f1 is the frequency corresponding to P1 and L1; f2 is the frequency corresponding to P2 and L2; The method of using the calibration station to analyze the Beidou satellite navigation signal to obtain a second combined pseudorange observation value and a second combined carrier phase observation value corresponding to each visible satellite includes: Where, P IF1 is the second combined pseudorange observation value; Φ IF1 is the second combined carrier phase observation value; P 11 is the fifth data obtained based on the observation data; P 12 is the sixth data obtained based on the observation data; L 11 is the seventh data obtained based on the observation data; L 12 is the eighth data obtained based on the observation data; f 11 P 11 and L 11 The corresponding frequency; f 12 P 12 and L 12 The corresponding frequency.

3. The time-frequency remote calibration method according to claim 2, characterized in that: The method further includes: Get the maximum value of the time difference between stations; Obtaining a difference value based on the maximum value of the inter-station time difference comparison and a preset average value of the inter-station time difference comparison; Determining whether the time measurement uncertainty is reasonable according to the difference and the time measurement uncertainty; If the time measurement uncertainty is greater than the difference, the time measurement uncertainty is reasonable.

4. The time-frequency remote calibration method according to claim 3, characterized in that: The first observation equation mathematical model includes a first sub-observation equation mathematical model and a second sub-observation equation mathematical model; The establishing of a first observation equation mathematical model using the first combined pseudorange observation value and the first combined carrier phase observation value comprises: The mathematical model of the first sub-observation equation is established using the first combined pseudorange observation value: P IF =ρ+c(dt-dT)+T+d m Where, P IF is the first combined pseudorange observation value; ρ is the satellite-ground geometric distance of the reference station, (x u ,y u ,z u ) is the receiver position of the reference station, (x s ,y s ,z s ) is the satellite position of the reference station; c is the speed of light; dt is the receiver clock error of the reference station; dT is the satellite clock error of the reference station; T is the tropospheric delay error of the reference station; d m is the multipath effect corresponding to the first combined pseudorange observation value; The mathematical model of the second sub-observation equation is established using the first combined carrier phase observation value: Φ IF =ρ+c(dt-dT)+T+N IF +δ m Where, Φ IF is the first combined carrier phase observation value; N IF is the first full cycle ambiguity; δ m is the multipath effect corresponding to the first combined carrier phase observation value.

5. The time-frequency remote calibration method according to claim 4, characterized in that: The second observation equation mathematical model includes a third sub-observation equation mathematical model and a fourth sub-observation equation mathematical model; The establishing of a second observation equation mathematical model using the second combined pseudorange observation value and the second combined carrier phase observation value comprises: The mathematical model of the third sub-observation equation is established using the second combined pseudorange observation value: P IF1 =ρ1+c(dt1-dT1)+T1+d m1 Where, P IF1 is the second combined pseudorange observation value; ρ1 is the satellite-to-ground geometric distance of the calibration station, (x u1 ,y u1 ,z u1 ) is the receiver position of the calibration station, (x1 s ,y1 s ,z1 s ) is the satellite position of the calibration station; c is the speed of light; dt1 is the receiver clock error of the calibration station; dT1 is the satellite clock error of the calibration station; T1 is the tropospheric delay error of the calibration station; d m1 is the multipath effect corresponding to the second combined pseudorange observation value; The mathematical model of the fourth sub-observation equation is established using the second combined carrier phase observation value: F IF1 =ρ1+c(dt1-dT1)+T1+N IF1 +d m1 Where, Φ IF1 is the second combined carrier phase observation value; N IF1 is the second full cycle ambiguity; δ m1 is the multipath effect corresponding to the second combined carrier phase observation value.

6. The time-frequency remote calibration method according to claim 5, characterized in that: The performing mathematical processing on the first observation equation mathematical model to obtain the first observation equation includes: Performing cycle slip detection and repair on the first combined carrier phase observation value in the first observation equation mathematical model; Performing error correction on the satellite position and the satellite clock error of the reference station in the mathematical model of the first observation equation; Parameter estimation is performed on the first integer ambiguity, the receiver position of the reference station, the receiver clock difference of the reference station, and the tropospheric delay error of the reference station in the mathematical model of the first observation equation.

7. The time-frequency remote calibration method according to claim 6, characterized in that: The performing mathematical processing on the second observation equation mathematical model to obtain the second observation equation includes: Performing cycle slip detection and repair on the second combined carrier phase observation value in the second observation equation mathematical model; Performing error correction on the satellite position and the satellite clock bias of the calibration station in the second observation equation mathematical model; Parameter estimation is performed on the second integer ambiguity, the receiver position of the calibration station, the receiver clock difference of the calibration station and the tropospheric delay error of the calibration station in the mathematical model of the second observation equation.

8. The time-frequency remote calibration method according to claim 7, characterized in that: Obtaining the inter-station comparison time difference according to the receiver clock difference of the reference station and the receiver clock difference of the calibration station includes: dt-dt1=(T A -T BDT )-(T B -T BDT )=T A -T B Where, T A is the local time of the base station; T B is the local time of the calibration station; T BDT This is the Beidou system time.

9. The time-frequency remote calibration method according to claim 8, characterized in that: The formula for calculating the time measurement uncertainty corresponding to the inter-station comparison time difference is: U=ku c Where k is the coverage factor; u c Combined uncertainty for time measurement.

10. The time-frequency remote calibration method according to claim 9, characterized in that: The calculation formula for the combined uncertainty of time measurement is: Where u A is the statistical value of the standard deviation of the time difference between stations; u B1 Uncertainty introduced by the calibration device of the reference station and the calibration device of the calibration station; u B2 The uncertainty introduced by the signal propagation path; u B3 The uncertainty introduced by the satellite end; u B4 The uncertainty introduced by temperature; u B5 The uncertainty introduced by the equipment calibration residual.

Images