Time comparison method and system for bidirectional pseudo-range measurement

Abstract

The invention relates to a time comparison method and system for bidirectional pseudo-range measurement. The method comprises the following steps: transmitting a paths of master pseudo-range ranging signals and w paths of slave pseudo-range ranging signals between master equipment and slave equipment; a master pseudo-range ranging values corresponding to the a master pseudo-range ranging signals and w slave pseudo-range ranging values corresponding to the w slave pseudo-range ranging signals are acquired; according to the a master pseudo-range ranging values and the w slave pseudo-range ranging values, determining the total number of electrons of an ionized layer on a ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device; or when the a paths of master pseudo-range ranging signals and the w paths of slave pseudo-range ranging signals meet the preset carrier frequency relationship, determining the clock difference between the master device and the slave device by using a master pseudo-range ranging values and w slave pseudo-range ranging values based on the preset carrier frequency relationship; and performing time synchronization on the master device and the slave device. According to the invention, the time delay influence of the ionosphere is eliminated, and the time synchronization accuracy is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of space technology, and particularly to a time comparison method and system for two-way pseudorange measurement. Background Art

[0002] The Global Navigation Satellite System (GNSS) is the current mainstream satellite navigation system. Internationally, there are the Beidou system in China, the GPS system in the United States, the Galileo system in Europe, and the Glonass system in Russia. The satellite navigation system is a very large and complex system, involving three major parts: operation and control, satellites, and users. It involves satellite-ground time synchronization between the operation and control stations and satellites, time synchronization between operation and control stations, satellite orbit determination technology, and user positioning and timing applications. Among them, the operation and control part monitors the satellite atomic clock time of the satellites to ensure the accuracy and reliability of the satellite time. At the same time, it also needs to determine the orbits of the satellites and provide ephemerides for users. The satellite part is the carrier that directly provides services to users, broadcasting three-way pseudorange signals, and the signals contain the ephemeris messages of the satellites. Users obtain the pseudorange values by measuring the pseudorange ranging signals, and realize user positioning and timing based on the pseudorange values and satellite ephemerides.

[0003] In the satellite navigation system, the operation and control part monitors the satellite orbits and satellite time to ensure the reliable long-term operation of the satellites. Among them, the time synchronization between the navigation satellite time and the operation and control system is the key. In addition to navigation satellites, space systems such as communication satellites and remote sensing satellites also require high-precision satellite-ground time synchronization requirements. The key to the positioning accuracy of the navigation satellite system lies in determining the satellite-borne atomic clock offset and its variation. Currently, it is mainly based on two-way pseudorange measurement to determine the satellite clock offset. The working principle is based on the fact that the signal propagation paths between the satellite and the ground are exactly the same, with the same satellite-ground spatial distance and tropospheric delay, but different ionospheric delays. Therefore, the clock offset is the difference between the measured pseudoranges divided by the speed of light or the difference between the corresponding time scales detected by the satellite and the ground station. The process is that both the satellite and the ground station transmit signals under the control of their local clocks at their respective independent clock face times. After the satellite and the ground station receivers receive the signals transmitted by each other, they complete the pseudorange measurement with their local clocks, and compare these two pseudorange ranging values to obtain the clock offset between the satellite and the ground station. The present application provides a new calculation method to achieve satellite-ground time synchronization. This method can also select the optimal carrier frequency for the satellite-ground time synchronization part of China's Beidou satellite navigation system, so as to obtain better results.

[0004] It should be noted that the information disclosed in the above background art section is only used to strengthen the understanding of the background of the present disclosure. Therefore, it may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the embodiments of the present disclosure is to provide a time comparison method for two-way pseudorange measurement and a time comparison method, which can eliminate the influence of ionospheric delay and improve the accuracy of time synchronization.

[0006] According to the first aspect of the embodiments of the present disclosure, a time comparison method for two-way pseudorange measurement is provided, which is applied to a time comparison system for two-way pseudorange measurement. The system includes a master device and a slave device connected by communication, and includes:

[0007] Transmit a main pseudorange ranging signal of a paths and a slave pseudorange ranging signal of w paths between the master device and the slave device; wherein, the main pseudorange ranging signal of a paths and the slave pseudorange ranging signal of w paths include at least three different carrier frequencies, a and w are both positive integers, and a + w ≥ 3;

[0008] Obtain the main pseudorange ranging value of the main pseudorange ranging signal of a paths and the slave pseudorange ranging value of the slave pseudorange ranging signal of w paths;

[0009] Determine the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device according to the a main pseudorange ranging values and the w slave pseudorange ranging values, or,

[0010] When the carrier frequencies of the main pseudorange ranging signal of a paths and the slave pseudorange ranging signal of w paths satisfy a preset carrier frequency relationship, based on the preset carrier frequency relationship, use the a main pseudorange ranging values and the w slave pseudorange ranging values to determine the clock difference between the master device and the slave device;

[0011] Transmit the determined clock difference between the master device and the slave device to the slave device or the master device, so that the time between the master device and the slave device is synchronized.

[0012] In an exemplary embodiment of the present disclosure, the determining the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device according to the a main pseudorange ranging values and the w slave pseudorange ranging values includes:

[0013] Perform correction processing on the a main pseudorange ranging values and the w slave pseudorange ranging values respectively to obtain the a corrected main pseudorange ranging values and the w corrected slave pseudorange ranging values;

[0014] Use the a corrected main pseudorange ranging values and the w corrected slave pseudorange ranging values to determine the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device.

[0015] In an exemplary embodiment of the present disclosure, determining the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device by using the a corrected master pseudorange ranging values and the w corrected slave pseudorange ranging values includes:

[0016] Performing a difference operation on the a corrected master pseudorange ranging values and the w corrected slave pseudorange ranging values to obtain a difference matrix;

[0017] Based on the difference matrix and the carrier frequencies of the a master pseudorange ranging signals and the w slave pseudorange ranging signals, constructing a matrix equation with the total number of electrons in the ionosphere and the clock difference as unknowns:

[0018] Solving the matrix equation to obtain the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device.

[0019] In an exemplary embodiment of the present disclosure, the relationship between the carrier frequencies of the a master pseudorange ranging signals and the w slave pseudorange ranging signals satisfying a preset carrier frequency relationship is expressed as:

[0020]

[0021] where V represents a real constant value, a represents the number of master pseudorange ranging signals, i represents the number of the master pseudorange ranging signal, w represents the number of slave pseudorange ranging signals, j represents the number of the slave pseudorange ranging signal, f u,j (n) represents the carrier frequency of the slave pseudorange ranging signal numbered j at the nth moment, f z,i (n) represents the carrier frequency of the master pseudorange ranging signal numbered i at the nth moment.

[0022] In an exemplary embodiment of the present disclosure, when the carrier frequencies of the a master pseudorange ranging signals and the w slave pseudorange ranging signals satisfy the preset carrier frequency relationship, determining the clock difference between the master device and the slave device by using the a master pseudorange ranging values and the w slave pseudorange ranging values includes:

[0023] Performing correction processing on the a master pseudorange ranging values and the w slave pseudorange ranging values respectively to obtain a corrected master pseudorange ranging values and w corrected slave pseudorange ranging values;

[0024] Performing mean processing on the a corrected master pseudorange ranging values to obtain an average master pseudorange ranging value;

[0025] Performing mean processing on the w corrected slave pseudorange ranging values to obtain an average slave pseudorange ranging value;

[0026] Perform a difference operation on the average master pseudo-range ranging value and the average slave pseudo-range ranging value to determine the clock difference between the master device and the slave device.

[0027] In an exemplary embodiment of the present disclosure, the correcting the a master pseudo-range ranging values and the w slave pseudo-range ranging values respectively further includes:

[0028] Use the pseudo-range ranging expression to represent the a master pseudo-range ranging values and the w slave pseudo-range ranging values, and obtain the expressions of the a master pseudo-range ranging values and the expressions of the w slave pseudo-range ranging values;

[0029] Perform correction processing on the expressions of the a master pseudo-range ranging values and the expressions of the w master pseudo-range ranging values respectively.

[0030] In an exemplary embodiment of the present disclosure, the expression of the master pseudo-range ranging value is:

[0031]

[0032] where i = 1, 2,..., a, i is a positive integer, ρ z,i (n) represents the master pseudo-range ranging value numbered i at the nth moment, R true,z,i (n) represents the actual space distance traveled by the master pseudo-range ranging signal numbered i at the nth moment; I z,i (n) represents the ionospheric delay of the master pseudo-range ranging signal numbered i at the nth moment; T duiliu,z,i (n) represents the tropospheric delay of the master pseudo-range ranging signal numbered i at the nth moment; X z,i (n) represents the hardware device delay of the master pseudo-range ranging signal numbered i at the nth moment, and the hardware device delay of the pseudo-range ranging signal includes the transmission delay of the master pseudo-range ranging signal numbered i and the reception delay of the master pseudo-range ranging signal numbered i; c represents the speed of light, unit; δt s (n) represents the clock difference of the master device relative to the system time at the nth moment; δt z (n) represents the clock difference of the slave device relative to the system time at the nth moment, sagnac zz (n) represents the Sagnac effect delay of the master pseudo-range ranging signal at the nth moment;

[0033] The expression of the slave pseudo-range ranging value is:

[0034]

[0035] where j = 1, 2,..., w, j is a positive integer, ρ u,j (n) represents the slave pseudo-range ranging value numbered j at the nth moment, R true,u,j(n) represents the true space distance that the pseudorange ranging signal numbered j has passed at the nth moment, I u,j (n) represents the ionospheric delay of the pseudorange ranging signal numbered j at the nth moment, T duiliu,u,j (n) represents the tropospheric delay of the pseudorange ranging signal numbered j at the nth moment, X u,j (n) represents the hardware device delay of the pseudorange ranging signal numbered j at the nth moment. The hardware device delay of the pseudorange ranging signal includes the transmission delay of the pseudorange ranging signal numbered j and the reception delay of the pseudorange ranging signal numbered j, sagnac uu (n) represents the Sagnac effect delay of the pseudorange ranging signal at the nth moment.

[0036] In an exemplary embodiment of the present disclosure, the corrected primary pseudorange ranging value is:

[0037]

[0038] where i = 1, 2,..., a, i is a positive integer, ρ z,i,a (n) represents the corrected primary pseudorange ranging value numbered i;

[0039] The corrected secondary pseudorange ranging value is:

[0040]

[0041] where j = 1, 2,..., w, j is a positive integer, ρ u,j,a (n) represents the corrected secondary pseudorange ranging value numbered j.

[0042] According to the second aspect of the embodiments of the present disclosure, a time comparison system for two-way pseudorange measurement is provided. The system is applied to the time synchronization method for two-way pseudorange measurement as described in any one of the above, and the system includes a computing device and a master device and a slave device that are communicatively connected;

[0043] where there are a primary pseudorange ranging signals and w secondary pseudorange ranging signals between the master device and the slave device. The a primary pseudorange ranging signals and w secondary pseudorange ranging signals include at least three different carrier frequencies, and a + w ≥ 3;

[0044] The computing device is communicatively connected to the master device and the slave device respectively, and is configured to receive the secondary pseudorange ranging value measured by the master device and the primary pseudorange ranging value measured by the slave device, and determine the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device.

[0045] In an exemplary embodiment of the present disclosure, the master device includes a first pseudo-range ranging device, a first time-frequency device, and a first pseudo-range generating device, and the slave device includes a second pseudo-range ranging device, a second time-frequency device, and a second pseudo-range generating device;

[0046] The first pseudo-range ranging device and the first pseudo-range generating device are communicatively connected, the first pseudo-range ranging device and the first pseudo-range generating device are set with a zero baseline, and the first pseudo-range ranging device and the first pseudo-range generating device are respectively connected to the first time-frequency device. The first time-frequency device is configured to provide time-frequency signals to the first pseudo-range ranging device and the first pseudo-range generating device. The first pseudo-range generating device is configured to generate and broadcast the master pseudo-range ranging signal, and the first pseudo-range ranging device is configured to receive and measure the slave pseudo-range ranging signal;

[0047] The second pseudo-range ranging device and the second pseudo-range generating device are communicatively connected, the second pseudo-range ranging device and the second pseudo-range generating device are set with a zero baseline, and the second pseudo-range ranging device and the second pseudo-range generating device are respectively connected to the second time-frequency device. The second time-frequency device is configured to provide time-frequency signals to the second pseudo-range ranging device and the second pseudo-range generating device. The second pseudo-range generating device is configured to generate and broadcast the slave pseudo-range ranging signal, and the second pseudo-range ranging device is configured to receive and measure the master pseudo-range ranging signal.

[0048] The technical solution provided by the present disclosure may include the following beneficial effects:

[0049] In the embodiment of the present disclosure, on the one hand, the time comparison method of this embodiment shows that the total ionospheric electrons on the ranging signal path between the master device and the slave device can be determined based on a master pseudo-range ranging values and w slave pseudo-range ranging values, and at the same time, the clock difference between the master device and the slave device can be determined. Compared with the traditional two-way pseudo-range measurement method, the error influence of the ionospheric delay can be overcome, and the accuracy of the determined clock difference can be improved. On the other hand, the time comparison method of this embodiment also shows that the carrier frequencies of the a-way master pseudo-range ranging signals and the carrier signals of the w-way slave pseudo-range ranging signals are limited by preset carrier frequency relationships. In this way, the clock difference between the master device and the slave device can be directly determined using a master pseudo-range ranging values and w slave pseudo-range ranging values, without calculating the total ionospheric electrons and ensuring the elimination of the ionospheric delay influence at the same time.

[0050] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0052] Figure 1 A flowchart showing the steps of the time comparison method in an exemplary embodiment of the present disclosure;

[0053] Figure 2 A simplified schematic diagram showing the time comparison system for two-way pseudorange measurement in an exemplary embodiment of the present disclosure;

[0054] Figure 3 A schematic diagram showing the internal structures of the master device and the slave device in an exemplary embodiment of the present disclosure. Detailed implementation manners

[0055] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0056] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0057] In this example embodiment, a time comparison method for two-way pseudorange measurement is first provided. The time comparison method for two-way pseudorange measurement is applied to a time comparison system for two-way pseudorange measurement, and the time comparison system for two-way pseudorange measurement includes a computing device 100 and a master device 200 and a slave device 300 that are communicatively connected. Referring to Figure 1 as shown, the time comparison method may include the following steps:

[0058] Step S101: Transmit a primary pseudorange ranging signal paths and w secondary pseudorange ranging signal paths between the master device 200 and the slave device 300; wherein, the a primary pseudorange ranging signal paths and the w secondary pseudorange ranging signal paths include at least three different carrier frequencies, a and w are both positive integers, and a + w ≥ 3;

[0059] Step S102: Obtain a primary pseudorange ranging values corresponding to the a primary pseudorange ranging signal paths and w secondary pseudorange ranging values corresponding to the w secondary pseudorange ranging signal paths;

[0060] Step S103: Determine the total number of electrons in the ionosphere on the ranging signal path between the master device 200 and the slave device 300 and the clock offset between the master device 200 and the slave device 300 according to the a primary pseudorange ranging values and the w secondary pseudorange ranging values, or,

[0061] When the carrier frequencies of the a primary pseudorange ranging signal paths and the carrier frequencies of the w secondary pseudorange ranging signal paths satisfy a preset carrier frequency relationship, based on the preset carrier frequency relationship, use the a primary pseudorange ranging values and the w secondary pseudorange ranging values to determine the clock offset between the master device 200 and the slave device 300;

[0062] Step S104: Transmit the determined clock offset between the master device 200 and the slave device 300 to the slave device 300 or the slave device 300, so that the time synchronization between the slave device 300 and the slave device 300 is achieved.

[0063] In an embodiment of the present disclosure, on the one hand, the time comparison method of this embodiment provides that the total number of electrons in the ionosphere on the ranging signal path between the master device 200 and the slave device 300 can be determined according to the a primary pseudorange ranging values and the w secondary pseudorange ranging values, and at the same time, the clock offset between the master device 200 and the slave device 300 can also be determined. Compared with the traditional two-way pseudorange measurement method, the error influence of the ionospheric delay can be overcome, and the accuracy of the determined clock offset can be improved. On the other hand, the time comparison method of this embodiment also provides that the carrier frequencies of the a primary pseudorange ranging signal paths and the carrier frequencies of the w secondary pseudorange ranging signal paths are limited by a preset carrier frequency relationship, so that the clock offset between the master device 200 and the slave device 300 can be directly determined by using the a primary pseudorange ranging values and the w secondary pseudorange ranging values, without calculating the total number of electrons in the ionosphere and ensuring the elimination of the ionospheric delay influence at the same time.

[0064] It should be noted that before explaining each step of the above method in the exemplary embodiment in more detail, the system adapted to this method will be introduced first, so as to more clearly understand the time comparison method proposed in this embodiment.

[0065] Refer to Figure 2As shown in the figure, the system includes a computing device 100, a master device 200 and a slave device 300 that are communicatively connected; wherein, there are two main pseudorange ranging signals and one slave pseudorange ranging signal between the master device 200 and the slave device 300, and the two main pseudorange ranging signals and the one slave pseudorange ranging signal include at least three different carrier frequencies, a + w ≥ 3; the computing device 100 is communicatively connected to the master device 200 and the slave device 300 respectively, and is configured to receive the pseudorange ranging values measured by the master device 200 and the slave device 300, and determine the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device. This system can be applied to the aerospace system, and typically can be a space-ground system composed of a user station and a satellite, and the user station monitors the clock difference between the satellite and the user station and the ionospheric delay on the ranging signal path. Specific applications of the two-way pseudorange measurement system, for example, can include satellite navigation, etc.

[0066] Exemplarily, referring to Figure 2 As shown in the figure, two main pseudorange ranging signals and one slave pseudorange ranging signal are shown. fz,1 and fz,2 respectively represent the carrier frequencies of the two main pseudorange ranging signals, and fu,1 represents the carrier frequency of one slave pseudorange ranging signal, unit: Hz. The two main pseudorange ranging signals can be broadcast by the master device 200 and received by the slave device 300, and the slave device 300 measures the two received main pseudorange ranging signals to obtain two main pseudorange ranging values; the one slave pseudorange ranging signal can be broadcast by the slave device 300 and received by the master device 200, and the master device 200 measures the one received slave pseudorange ranging signal to obtain one slave pseudorange ranging value.

[0067] Of course, the two main pseudorange ranging signals can also be broadcast by the slave device 300 and received by the master device 200; and the one slave pseudorange ranging signal can be broadcast by the master device 200 and received by the slave device 300, and this embodiment does not make any restrictions on the comparison. It should be noted that the master device 200 and the slave device 300 both synchronously measure the main pseudorange ranging signal and the slave pseudorange ranging signal at a preset time interval to obtain the corresponding pseudorange ranging values.

[0068] It should be noted that in the embodiments of the present application, the pseudorange ranging signal refers to the signal obtained by modulating the ranging code signal in the carrier signal. In some specific embodiments, the ranging code can be selected from pseudocode, Weil code, M code, etc., and no special limitation is made on the specific selection of the ranging code in the present application. And it can be understood that the pseudorange ranging signals described in the embodiments of the present application are all spread spectrum signals. When multiple spread spectrum signals are transmitted and received, the relationship between the carrier frequency and the ranging code is processed according to the spread spectrum communication technology, the carrier frequency multiplexing technology and the code division multiple access communication technology, which will not be elaborated here.

[0069] Exemplarily, referring to Figure 3 As shown in [FIGURE], the internal structural diagrams of the master device 200 and the slave device 300 are shown. Among them, the master device 200 includes a first pseudorange ranging device 210, a first time-frequency device 220, and a first pseudorange generating device 230. The slave device 300 includes a second pseudorange ranging device 310, a second time-frequency device 320, and a second pseudorange generating device 330.

[0070] It should be noted that a zero baseline setting is made between the first pseudorange ranging device and the first pseudorange generating device. The so-called zero baseline setting does not mean that the distance between the first pseudorange ranging device 210 and the first pseudorange generating device 230 is 0, but that the distance setting between them should satisfy that the space paths experienced by the master pseudorange ranging signal and the slave pseudorange ranging signal are approximately the same. When the distance between the first pseudorange ranging device 210 and the first pseudorange generating device 230 becomes smaller and smaller and can be integrated into one device, the approximation gradually becomes the same, with the same space distance between the satellite and the ground, the same tropospheric delay, and the same total electron content of the ionosphere.

[0071] Based on the zero baseline setting between the first pseudorange ranging device and the first pseudorange generating device, and the zero baseline setting between the second pseudorange ranging device and the second pseudorange generating device, the master pseudorange ranging signal and the slave pseudorange ranging signal pass through exactly the same atmospheric path, and the total electron content of the ionosphere experienced by the ranging signal is exactly the same. Therefore, there are the following equations (6) and (7):

[0072] R true,z,1 (n) = R true,z,2 (n) = R true,u,1 (n) = R true,u,2 (n) = R true,u,3 (n) (6)

[0073] T duiliu,z,1 (n) = T duiliu,z,2 (n) = T duiliu,u,1 (n) = T duiliu,u,2 (n) = T duiliu,u,3 (n) (7)

[0074] Wherein, R true,z,1 (n), R true,z,2 (n) represent the true space distances passed by the master pseudorange ranging signals numbered 1 and 2 at the nth moment, unit: meter; T duiliu,z,1 (n), T duiliu,z,2 (n) represent the tropospheric delays of the master pseudorange ranging signals numbered 1 and 2 at the nth moment, unit: meter; R true,u,1 (n), R true,u,2 (n), R true,u,3Let \(R^{(n)}\) denote the true space distance that the pseudo-range ranging signals numbered 1, 2, and 3 pass through at the \(n\)th moment, with the unit of meter; \(T\). duiliu,u,1 \(R^{(n)}\), \(T\). duiliu,u,2 \(R^{(n)}\), \(T\). duiliu,u,3 Let \(R_{\text{tropo}}^{(n)}\) denote the tropospheric delay of the pseudo-range ranging signals numbered 1, 2, and 3 at the \(n\)th moment, with the unit of meter.

[0075] When the slave device 300 is a user station, the user station can use a second time-frequency device 320. Specifically, the second pseudo-range ranging device 310 and the second pseudo-range generating device 330 of the user station use a second time-frequency device 320. In actual use, the preset time interval mentioned above can be set to 1 s, for example. The second pseudo-range ranging device 310 performs measurements at the rising edge or falling edge of the 1PPS (1 Pulse Per Second) signal.

[0076] The first pseudo-range generating device and the second pseudo-range generating device have transmission delays; the first pseudo-range ranging device and the second pseudo-range ranging device have reception delays. The transmission delay of the pseudo-range generating device refers to the delay generated during the process of generating and transmitting the main pseudo-range ranging signal by the pseudo-range generating device. The reception delay of the pseudo-range ranging device refers to the delay generated during the process of receiving the pseudo-range ranging signal sent by the other party and generating the pseudo-range ranging value by the pseudo-range ranging device.

[0077] It should be noted that in the pseudo-range ranging value, the Sagnac effect delay of the satellite needs to be obtained. The Sagnac effect delay requires the coordinates of the user station and the satellite. The coordinates of the satellite can be obtained from the known satellite ephemeris, and the coordinates of the user station can be obtained through the existing positioning method. In this way, the coordinate information required by the method of the embodiment of the present application can be obtained, and then the Sagnac effect delay can be obtained.

[0078] It should also be noted that in the pseudo-range ranging value, there is no relativistic time delay effect term. This is because in reality, satellites in space have time-frequency systems to provide time and frequency. According to the theory of relativity, the clocks on the satellites will produce corresponding relativistic effect delays due to relativity. For the relativistic effect delays of the satellite clocks, existing methods can be used to solve them. For example, the satellite clocks have been adjusted before being launched, and after adjustment, the satellite clocks are the same as the clocks on the ground without relativistic effect delays. For specific details, reference can be made to the practices of the Beidou navigation satellite clocks regarding relativity.

[0079] Next, with reference to Figure 2 shown in, taking two main pseudo-range ranging signals and one slave pseudo-range ranging signal as an example, each step of the above method in this exemplary embodiment will be described in more detail.

[0080] In one embodiment, in step S103, when the two main pseudorange ranging signals and one slave pseudorange ranging signal include at least three different carrier frequencies, that is, fz,1, fz,2, and fu,1 are not equal to each other. The time comparison method provided in this embodiment can determine the total number of electrons in the ionosphere on the ranging signal path between the master device 200 and the slave device 300 and the clock difference between the master device 200 and the slave device 300 according to two main pseudorange ranging values corresponding to the two main pseudorange ranging signals and one slave pseudorange ranging value corresponding to one slave pseudorange ranging signal. Specifically, it may include the following steps:

[0081] Step S103M1: Perform correction processing on two main pseudorange ranging values and one slave pseudorange ranging value respectively to obtain the two corrected main pseudorange ranging values and one corrected slave pseudorange ranging value;

[0082] Step S103M2: Use the two corrected main pseudorange ranging values and one corrected slave pseudorange ranging value to determine the total number of electrons in the ionosphere on the ranging signal path between the master device 200 and the slave device 300 and the clock difference between the master device 200 and the slave device 300.

[0083] Further, step S103M2 may include the following steps:

[0084] Step S103M21: Subtract one slave pseudorange ranging value from two corrected main pseudorange ranging values respectively to obtain a difference matrix;

[0085] Step S103M22: Based on the difference matrix and the carrier frequencies of the two main pseudorange ranging signals and the carrier frequency of one slave pseudorange ranging signal, construct a matrix equation with the total number of electrons in the ionosphere and the clock difference as unknowns;

[0086] Step S103M23: Solve the matrix equation to obtain the total number of electrons in the ionosphere on the ranging signal path between the master device 200 and the slave device 300 and the clock difference between the master device 200 and the slave device 300.

[0087] Exemplarily, the correction processing in the above step S103M1 can be implemented through the following steps:

[0088] Use the pseudorange ranging expression to represent two main pseudorange ranging values and one slave pseudorange ranging value to obtain the expressions of the two main pseudorange ranging values and the expression of one slave pseudorange ranging value;

[0089] Perform correction processing on the expressions of the two main pseudorange ranging values and the expression of one main pseudorange ranging value respectively. Then, two corrected main pseudorange ranging values corresponding to the two main pseudorange ranging values and one corrected slave pseudorange ranging value corresponding to one slave pseudorange ranging value can be obtained.

[0090] Specifically, the main pseudo-range ranging value is characterized by a pseudo-range ranging expression, and the expression of the main pseudo-range ranging value shown in the following formula (2) is obtained:

[0091]

[0092] where i = 1, 2, ……, a, i is a positive integer, ρ z,i (n) represents the main pseudo-range ranging value numbered i at the nth moment, R true,z,i (n) represents the actual space distance traveled by the main pseudo-range ranging signal numbered i at the nth moment; I z,i (n) represents the ionospheric delay of the main pseudo-range ranging signal numbered i at the nth moment; T duiliu,z,i (n) represents the tropospheric delay of the main pseudo-range ranging signal numbered i at the nth moment; X z,i (n) represents the hardware device delay of the main pseudo-range ranging signal numbered i at the nth moment. The hardware device delay of the pseudo-range ranging signal includes the transmission delay of the main pseudo-range ranging signal numbered i and the reception delay of the main pseudo-range ranging signal numbered i; c represents the speed of light, unit; δt s (n) represents the clock error of the main device 200 relative to the system time at the nth moment; δt z (n) represents the clock error of the slave device 300 relative to the system time at the nth moment, sagnac zz (n) represents the Sagnac effect delay of the main pseudo-range ranging signal at the nth moment;

[0093] Then the two obtained main pseudo-range ranging values are respectively as follows:

[0094]

[0095] where ρ z,1 (n) represents the main pseudo-range ranging value corresponding to i = 1, ρ z,2 (n) represents the main pseudo-range ranging value corresponding to i = 2, which are respectively called the first main pseudo-range ranging value and the second main pseudo-range ranging value;

[0096] The slave pseudo-range ranging value is characterized by a pseudo-range ranging expression, and the expression of the slave pseudo-range ranging value shown in the following formula (3) is obtained:

[0097]

[0098] where j = 1, 2, ……, w, j is a positive integer, ρ u,j (n) represents the slave pseudo-range ranging value numbered j at the nth moment, R true,u,j (n) represents the actual space distance traveled by the slave pseudo-range ranging signal numbered j at the nth moment, Iu,j (n) represents the ionospheric delay of the pseudo-range ranging signal numbered j at the nth moment, T duiliu,u,j (n) represents the tropospheric delay of the pseudo-range ranging signal numbered j at the nth moment, X u,j (n) represents the hardware device delay of the pseudo-range ranging signal numbered j at the nth moment. The hardware device delay of the pseudo-range ranging signal includes the transmission delay of the pseudo-range ranging signal numbered j and the reception delay of the pseudo-range ranging signal numbered j, sagnac uu (n) represents the Sagnac effect delay of the pseudo-range ranging signal at the nth moment;

[0099] Then a pseudo-range ranging value obtained is as follows:

[0100]

[0101] Among them, ρ u,1 (n) represents the pseudo-range ranging value corresponding to i = 1 of the pseudo-range ranging signal, which is called the first pseudo-range ranging value.

[0102] Perform correction processing on the main pseudo-range ranging value according to formula (4), and perform correction processing on the secondary pseudo-range ranging value according to formula (5). Formulas (4) and (5) are expressed as follows:

[0103]

[0104] Among them, ρ z,i,a (n) represents a corrected main pseudo-range ranging value, i = 1, 2,..., a, and i is a positive integer;

[0105]

[0106] Among them, ρ u,j,a (n) represents the corrected secondary pseudo-range ranging value numbered 1, j = 1, 2,..., w, and j is a positive integer.

[0107] Specifically, the two corrected main pseudo-range ranging values obtained are as follows:

[0108]

[0109] Among them, ρ z,1,a (n) represents the corrected main pseudo-range ranging value corresponding to i = 1, ρ z,2,a (n) represents the corrected main pseudo-range ranging value corresponding to i = 2;

[0110] A corrected secondary pseudo-range ranging value obtained is as shown:

[0111]

[0112] Among them, ρ u,1,a (n) represents the corrected pseudo-range ranging value corresponding to when the number i = 1.

[0113] Exemplarily, based on the above formulas (11), (12), and (13), in step S103M21, the difference between the two corrected primary pseudo-range ranging values and a corrected secondary pseudo-range ranging value is processed to obtain the following difference matrix:

[0114]

[0115] Among them, b represents the difference matrix, TEC(n) represents the total number of electrons in the ionosphere on the ranging signal path between the master device 200 and the slave device 300 at the nth moment, Q ion represents the ionospheric delay coefficient, f z,1 (n) represents the carrier frequency of the first primary pseudo-range ranging signal at the nth moment, unit: Hz, f z,2 (n) represents the carrier frequency of the second primary pseudo-range ranging signal at the nth moment, unit: Hz, f u,1 (n) represents the carrier frequency of the first secondary pseudo-range ranging signal at the nth moment, unit: Hz;

[0116] It should be specifically pointed out that: Q ion is the ionospheric delay coefficient, which is released by some international institutions. As people's research on ionospheric delay deepens, the ionospheric delay coefficient becomes more and more accurate. The ionospheric delay coefficient was once 40.28, 40.30, and currently it is 40.309. In the future, there may be a more accurate ionospheric delay coefficient. This application does not make special limitations on the ionospheric delay coefficient and takes the latest released value. In this embodiment, Q ion takes the value of 40.309.

[0117] Furthermore, in step S103M22, based on the difference matrix b, the carrier frequencies of the two primary pseudo-range ranging signals, and the carrier frequency of one secondary pseudo-range ranging signal, a matrix equation as shown in the following formula (17) is constructed with the total number of electrons in the ionosphere and the clock error as unknowns:

[0118]

[0119] Among them, G represents a 2×2 matrix;

[0120] Finally, in step S103M23, the matrix equation is solved to obtain the solution of the equation as shown in the following formula (19):

[0121]

[0122] Among them, the matrix G T is the transpose of the matrix G.

[0123] In practice, there will inevitably be errors in the master pseudo-range ranging value and the slave pseudo-range ranging value. When applying the above matrix calculation, there will also be errors in the clock difference and the total ionospheric electron content obtained.

[0124] Let (G T G) -1 = H in formula (19). H is a 2×2 matrix, where h 11 represents the element in the first row and first column of matrix H, which is the amplification factor of the clock difference error caused by the error of the pseudo-range ranging value. The smaller this value is, the better; h 22 represents the element in the second row and second column of matrix H, which is the amplification factor of the total ionospheric electron content error caused by the error of the pseudo-range ranging value. This value is also the smaller the better.

[0125] It should be noted that after obtaining the value of c·(δt z (n)-δt s (n)), dividing it by the speed of light c can obtain the clock difference δt z (n)-δt s (n) between the master device 200 and the slave device 300. And when the calculation device 100 calculates the clock difference between the master device 200 and the slave device 300 according to formula (19), it can also calculate the total ionospheric electron content TEC(n) on the ranging signal path between the master device 200 and the slave device 300.

[0126] In addition, considering that in the actual calculation process, the value of the total ionospheric electron content TEC(n) is relatively large, it can be set that TEC(n) = x(n)×TECU, TECU = 10 16 , the unit of the total ionospheric electron content TEC(n) is electrons per square meter (el / m 2 ). At this time, matrix G becomes G m :

[0127]

[0128] Solve the matrix equation to obtain the result as in formula (21):

[0129]

[0130] When the master device 200 broadcasts three master pseudo-range ranging signals and the slave device 300 broadcasts one slave pseudo-range signal, such as when China's Beidou navigation satellite broadcasts three master pseudo-range ranging signals and the ground station broadcasts one slave pseudo-range ranging signal. The above method can be used for calculation. At this time, the specific matrix G and matrix b are respectively:

[0131]

[0132]

[0133] Among them, b represents the difference matrix when the master device 200 broadcasts three master pseudorange ranging signals and the slave device 300 broadcasts one slave pseudorange signal, and f z,3 (n) represents the carrier frequency of the third master pseudorange ranging signal at the nth moment, unit: Hz, ρ z,3,a (n) represents the corrected master pseudorange ranging value corresponding to i = 3 at the nth moment;

[0134] Then, apply formula (19) to solve, and obtain the clock difference between the master device 200 and the slave device 300 under this working condition and the total number of electrons in the ionosphere on the ranging signal path between the master device 200 and the slave device 300.

[0135] When the above matrix method is applied to China's Beidou Navigation Satellite System, when the Beidou navigation satellite broadcasts navigation signals with carrier frequencies of fz,1 = B1 = 1575.42 MHz, fz,2 = B2 = 1191.795 MHz, and fz,3 = B3 = 1268.52 MHz respectively, according to matrix H, the optimal fu,1 = 1318 MHz.

[0136] In another embodiment, also taking Figure 2 the two master pseudorange ranging signals and one slave pseudorange ranging signal shown in as an example, in step S103, for the case where the two master pseudorange ranging signals and one slave pseudorange ranging signal also satisfy a preset carrier frequency relationship, the time comparison method provided in this embodiment can determine the clock difference between the master device 200 and the slave device 300 based on the preset carrier frequency relationship and using the two master pseudorange ranging values and one slave pseudorange ranging value, specifically including the following steps:

[0137] Step S103N1: Perform correction processing on the two master pseudorange ranging values and one slave pseudorange ranging value respectively to obtain two corrected master pseudorange ranging values and one corrected slave pseudorange ranging value;

[0138] Step S103N2: Perform mean processing on the two corrected master pseudorange ranging values to obtain an average master pseudorange ranging value;

[0139] Step S103N3: Perform mean processing on one corrected slave pseudorange ranging value to obtain an average slave pseudorange ranging value; It should be noted that when performing mean processing on one corrected slave pseudorange ranging value, the average slave pseudorange ranging value is the corrected slave pseudorange ranging value;

[0140] Step S103N4: Perform subtraction processing on the average master pseudorange ranging value and the average slave pseudorange ranging value to determine the clock difference between the master device 200 and the slave device 300.

[0141] Exemplarily, the correction process in step S103N1 can be performed with reference to the correction process in step S103M1. Through the correction process, two corrected primary pseudorange ranging values represented by formulas (11) and (12), and one corrected secondary pseudorange ranging value represented by formula (13) can be obtained.

[0142] Furthermore, in step S103N2, the two corrected primary pseudorange ranging values are averaged to obtain the average primary pseudorange ranging value as shown in formula (24):

[0143]

[0144] where ρ z,mean (n) represents the average primary pseudorange ranging value;

[0145] In step S103N3, the one corrected secondary pseudorange ranging value is averaged to obtain the average secondary pseudorange ranging value as shown in formula (25):

[0146]

[0147] where ρ u,mean (n) represents the average secondary pseudorange ranging value;

[0148] Finally, in step S103N4, the difference between the average primary pseudorange ranging value and the average secondary pseudorange ranging value is processed to obtain formula (26) as follows:

[0149]

[0150] where I z,1 (n) represents the ionospheric delay of the first primary pseudorange ranging signal at the nth moment, I z,2 (n) represents the ionospheric delay of the second primary pseudorange ranging signal at the nth moment, I u,1 (n) represents the ionospheric delay of the first secondary pseudorange ranging signal at the nth moment.

[0151] It should be noted that the above formula (26) still contains the ionospheric linear combination term Next, a specific explanation will be given on how to eliminate the influence of ionospheric delay by means of the preset carrier frequencies satisfied by the carrier frequencies of the primary pseudorange ranging signal and the secondary pseudorange ranging signal.

[0152] Specifically, in this embodiment, it is defined that the relationship of the preset carrier frequencies satisfied by the a-channel primary pseudorange ranging signal and the w-channel secondary pseudorange ranging signal is:

[0153]

[0154] Wherein, V represents a real constant value, a represents the number of primary pseudorange ranging signals, i represents the number of the primary pseudorange ranging signal; w represents the number of secondary pseudorange ranging signals; j represents the number of the secondary pseudorange ranging signal; f u,j (n) represents the carrier frequency of the secondary pseudorange ranging signal numbered j at the nth moment, f z,i (n) represents the carrier frequency of the primary pseudorange ranging signal numbered i at the nth moment.

[0155] Then, for the two primary pseudorange ranging signals and one secondary pseudorange ranging signal in Figure 2 , formula (1) is specifically expressed as formula (27) below:

[0156]

[0157] Wherein, f u,1 (n) represents the carrier frequency of the secondary pseudorange ranging signal numbered 1 at the nth moment, f z,1 (n) represents the carrier frequency of the primary pseudorange ranging signal numbered 1 at the nth moment, f z,2 (n) represents the carrier frequency of the primary pseudorange ranging signal numbered 2 at the nth moment;

[0158] In formula (27), multiply both sides by Q ion ×TEC(n) to obtain a linear combination of the ionospheric delays of the primary pseudorange ranging signal and the secondary pseudorange ranging signal, as shown in formula (28):

[0159]

[0160] Wherein, I ion (n) represents a linear combination of the ionospheric delays of the primary pseudorange ranging signal and the secondary pseudorange ranging signal;

[0161] For the preset carrier frequency relationship shown in formula (27), when it evolves into the form shown in the following formula (29):

[0162]

[0163] Wherein, f u,1 (n) represents the carrier frequency of the secondary pseudorange ranging signal numbered 1 at the nth moment, f z,1 (n) represents the carrier frequency of the primary pseudorange ranging signal numbered 1 at the nth moment, f z,2 (n) represents the carrier frequency of the primary pseudorange ranging signal numbered 2 at the nth moment;

[0164] Then the linear combination result of the ionospheric delay shown in formula (28) is also 0, so that the linear combination term of the main ionospheric delay in formula (26) is 0, completely eliminating the ionospheric delay combination of the main pseudorange ranging signal and the slave pseudorange ranging signal, that is, completely eliminating the influence of the ionospheric delay error.

[0165] According to the above analysis, whether the linear combination term of the ionospheric delay in the result obtained by subtracting the average main pseudorange ranging value from the average slave pseudorange ranging value is completely eliminated, the final clock difference result is as shown in formula (30):

[0166]

[0167] where, δt z (n)-δt s (n) represents the clock difference between the master device 200 and the slave device 300.

[0168] Generally, it is recommended to make the combination result in the preset carrier frequency relationship be 0, and the obtained clock difference completely eliminates the ionospheric delay error. When the above method of using the preset carrier frequency is applied to China's Beidou Navigation Satellite System, when the Beidou navigation satellite broadcasts navigation signals with carrier frequencies of fz,1 = B1 = 1575.42 MHz and fz,2 = B2 = 1191.795 MHz respectively, when formula (29) is satisfied, fu,1 = 1344.160 MHz;

[0169] When the Beidou navigation satellite broadcasts navigation signals with carrier frequencies of fz,1 = B1 = 1575.42 MHz, fz,2 = B2 = 1191.795 MHz, and fz,3 = B3 = 1268.52 MHz respectively, when formula (f29) is satisfied, fu,1 = 1317.464 MHz;

[0170] After obtaining the value of c·(δt z (n)-δt s (n)), dividing it by the speed of light c can obtain the clock difference δt z (n)-δt s (n) between the satellite and the user station.

[0171] where, after the satellite obtains the clock difference between the satellite and the user station, it further uses this clock difference to synchronize its own clock with the system clock.

[0172] After calculating the clock difference between the satellite and the user station, when the clock difference δt z (n) of the user station relative to the system time is a known quantity, the clock difference δt s of the satellite relative to the system time can be easily obtained.(n), if the time of the ground operation and control station of the Beidou satellite navigation system is known, the clock difference between the operation and control station and the satellite is calculated by using the method of the present application, and then the satellite clock difference is obtained;

[0173] Conversely, when the clock difference δt s (n) of the satellite relative to the system time is a known quantity, it is easy to obtain the clock difference δt z (n) of the user station relative to the system time. At this time, the satellite can provide time service for the user station;

[0174] When the clock difference of the user station relative to the system time and the clock difference of the satellite relative to the system time are both unknown, the clock difference between the satellite and the user station is obtained.

[0175] The time comparison method of two-way pseudorange measurement provided by the embodiments of the present application can eliminate the influence of ionospheric delay and improve the accuracy of time synchronization between the master device 200 and the slave device 300. In addition, the time comparison method provided by the embodiments of the present application also has the following characteristics: the present application can independently obtain the total number of electrons in the ionosphere on the ranging signal path without the need for the total number of electrons in the ionosphere data provided by a third party, and can also provide the total number of electrons in the ionosphere data for other users; the present application can make full use of the carrier frequency information of the pseudorange ranging signal to obtain better clock difference results; the present application can not only obtain the total number of electrons in the ionosphere and the clock difference, but also optimize the selection of the carrier frequency of the pseudorange ranging signal, and select the best carrier frequency to obtain the best clock difference performance.

[0176] In this exemplary embodiment, a two-way pseudorange measurement time comparison system is also provided, which is applied to the time comparison method of two-way pseudorange measurement in the above embodiment. Refer to Figure 2 As shown in, the system includes a computing device 100 and a master device 200 and a slave device 300 connected by communication; wherein, there are a main pseudorange ranging signals and w slave pseudorange ranging signals between the master device 200 and the slave device 300, and the a main pseudorange ranging signals and the w slave pseudorange ranging signals include at least three different carrier frequencies, and a + w ≥ 3; the computing device 100 is respectively communicatively connected to the master device 200 and the slave device 300, and is configured to receive the pseudorange ranging values measured by the master device 200 or the slave device 300, and determine the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device satellite and the slave device. This system can be applied to the aerospace system, and typically can be a space-ground system composed of a user station and a satellite, and the user station monitors the clock difference between the satellite and the user station and the ionospheric delay on the ranging signal path. Specific applications of the two-way pseudorange measurement system, for example, can include satellite navigation, satellite communication, etc.

[0177] In one embodiment, the carrier frequencies of the a-channel master pseudorange ranging signals and the w-channel slave pseudorange ranging signals in the system satisfy a preset carrier frequency relationship, which is expressed as:

[0178]

[0179] where V represents a real constant, a represents the number of master pseudorange ranging signals, i represents the number of the master pseudorange ranging signal, w represents the number of slave pseudorange ranging signals, j represents the number of the slave pseudorange ranging signal, and f u,j (n) represents the carrier frequency of the slave pseudorange ranging signal numbered j at the nth moment, and f z,i (n) represents the carrier frequency of the master pseudorange ranging signal numbered i at the nth moment.

[0180] Exemplarily, as shown in reference Figure 2 , two master pseudorange ranging signals and one slave pseudorange ranging signal are shown. The two master pseudorange ranging signals can be broadcast by the master device 200 and received by the slave device 300. The slave device 300 measures the two received master pseudorange ranging signals to obtain the pseudorange ranging values of the two master pseudorange ranging signals; the one slave pseudorange ranging signal can be broadcast by the slave device 300 and received by the master device 200. The master device 200 measures the one received master pseudorange ranging signal to obtain the pseudorange ranging value of the one slave pseudorange ranging signal. Of course, the two master pseudorange ranging signals can also be broadcast by the slave device 300 and received by the master device 200; and the one slave pseudorange ranging signal can be broadcast by the master device 200 and received by the slave device 300. This embodiment does not make a limit on this comparison. It should be noted that both the master device 200 and the slave device 300 synchronously measure the master pseudorange ranging signals and the slave pseudorange ranging signals at preset time intervals to obtain the corresponding pseudorange ranging values.

[0181] Exemplarily, as shown in reference Figure 3 , the internal structure diagrams of the master device 200 and the slave device 300 are shown. Among them, the master device 200 includes a first pseudorange ranging device 210, a first time-frequency device 220, and a first pseudorange generating device 230, and the slave device 300 includes a second pseudorange ranging device 310, a second time-frequency device 320, and a second pseudorange generating device 330.

[0182] Among them, the first pseudo-range ranging device 210 and the first pseudo-range generating device 230 are communicatively connected, and the first pseudo-range ranging device 210 and the first pseudo-range generating device 230 are respectively connected to the first time-frequency device 220. The first time-frequency device 220 is configured to provide time-frequency signals to the first pseudo-range ranging device 210 and the first pseudo-range generating device 230. The first pseudo-range generating device 230 is configured to generate and broadcast the master pseudo-range ranging signal. The first pseudo-range ranging device 210 is configured to receive and measure the slave pseudo-range ranging signal;

[0183] Among them, the second pseudo-range ranging device 310 and the second pseudo-range generating device 330 are communicatively connected, and the second pseudo-range ranging device 310 and the second pseudo-range generating device 330 are respectively connected to the second time-frequency device 320. The second time-frequency device 320 is configured to provide time-frequency signals to the second pseudo-range ranging device 310 and the second pseudo-range generating device 330. The second pseudo-range generating device 330 is configured to generate and broadcast the slave pseudo-range ranging signal. The second pseudo-range ranging device 310 is configured to receive and measure the master pseudo-range ranging signal.

[0184] When the slave device 300 is a user station, the user station can use one second time-frequency device 320. Specifically, the second pseudo-range ranging device 310 and the second pseudo-range generating device 330 of the user station use one second time-frequency device 320. In actual use, the preset time interval mentioned above can be set to 1 s, for example. The second pseudo-range ranging device 310 performs measurement at the rising edge or falling edge of the 1PPS (1 Pulse Per Second) signal.

[0185] It should be noted that a zero baseline is set between the first pseudo-range ranging device and the first pseudo-range generating device. The so-called zero baseline setting does not mean that the distance between the first pseudo-range ranging device 210 and the first pseudo-range generating device 230 is 0, but the distance between them is set to satisfy that the spatial paths experienced by the master pseudo-range ranging signal and the slave pseudo-range ranging signal are approximately the same. When the distance between the first pseudo-range ranging device 310 and the first pseudo-range generating device 330 becomes smaller and smaller and can be integrated into one device, the approximation gradually becomes the same, with the same space distance between the satellite and the ground, the same tropospheric delay, and the same total electron content of the ionosphere.

[0186] It should be noted that the first pseudorange ranging device 210 and the first pseudorange generating device 230 are communicatively connected. The signal transmission between the first pseudorange ranging device 210 and the first pseudorange generating device 230 can be directly carried out, or can be realized through a third party between the first pseudorange ranging device 210 and the first pseudorange generating device 230. The second pseudorange ranging device 310 and the second pseudorange generating device 330 are communicatively connected. The signal transmission between the second pseudorange ranging device 310 and the second pseudorange generating device 330 can be directly carried out, or can be realized through a third party between the second pseudorange ranging device 310 and the second pseudorange generating device 330.

[0187] It should be noted that the computing device 100 is disposed in the master device 200 or in the slave device 300, or exists independently.

[0188] When the computing device 100 is disposed in the master device 200 or the slave device 300, the master device 200 uses the additional communication signal to perform data transmission with the slave device 300; or, when the computing device 100 is independently disposed, the computing device 100 communicates with the master device 200 and the slave device 300.

[0189] Regarding the system in the above embodiments, the specific manners in which each unit performs operations have been described in detail in the embodiments related to the method, and will not be elaborated here in detail.

[0190] It should be noted that although several units of the system for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiments of the present disclosure, the features and functions of the two or more units described above can be embodied in one unit. Conversely, the features and functions of one unit described above can be further divided and embodied by multiple units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the present disclosure. Those of ordinary skill in the art can understand and implement it without creative work.

[0191] After considering the specification and practicing the invention disclosed herein, those skilled in the art will readily conceive of other embodiments of the present disclosure. This application is intended to cover any variations, uses, or adaptations of the present disclosure, which follow the general principles of the present disclosure and include known common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the appended claims.

Claims

1. A time comparison method for two-way pseudorange measurement, applied to a time comparison system for two-way pseudorange measurement. The system includes a master device and a slave device connected by communication. It is characterized in that, Including: Transmitting a main pseudorange ranging signal and w slave pseudorange ranging signals between the master device and the slave device; wherein, the a main pseudorange ranging signals and the w slave pseudorange ranging signals include at least three different carrier frequencies, a and w are both positive integers, and a + w ≥ 3; Obtaining a main pseudorange ranging values corresponding to the a main pseudorange ranging signals and w slave pseudorange ranging values corresponding to the w slave pseudorange ranging signals; Determining the total ionospheric electrons on the ranging signal path between the master device and the slave device and the clock offset between the master device and the slave device according to the a main pseudorange ranging values and the w slave pseudorange ranging values, or When the carrier frequencies of the a main pseudorange ranging signals and the carrier frequencies of the w slave pseudorange ranging signals satisfy a preset carrier frequency relationship, based on the preset carrier frequency relationship, determining the clock offset between the master device and the slave device by using the a main pseudorange ranging values and the w slave pseudorange ranging values; Transmitting the determined clock offset between the master device and the slave device to the master device or the slave device to enable time synchronization between the master device and the slave device.

2. The time comparison method for two-way pseudorange measurement according to claim 1, wherein The determining the total ionospheric electrons on the ranging signal path between the master device and the slave device and the clock offset between the master device and the slave device according to the a main pseudorange ranging values and the w slave pseudorange ranging values includes: Performing correction processing on the a main pseudorange ranging values and the w slave pseudorange ranging values respectively to obtain a corrected main pseudorange ranging values and w corrected slave pseudorange ranging values; Using the a corrected main pseudorange ranging values and the w corrected slave pseudorange ranging values to determine the total ionospheric electrons on the ranging signal path between the master device and the slave device and the clock offset between the master device and the slave device.

3. The time comparison method for two-way pseudorange measurement according to claim 2, characterized in that, The using the a corrected main pseudorange ranging values and the w corrected slave pseudorange ranging values to determine the total ionospheric electrons on the ranging signal path between the master device and the slave device and the clock offset between the master device and the slave device includes: Performing a difference operation on the a corrected main pseudorange ranging values and the w corrected slave pseudorange ranging values to obtain a difference matrix; Based on the difference matrix and the carrier frequencies of the a main pseudorange ranging signals and the w slave pseudorange ranging signals, constructing a matrix equation with the total ionospheric electrons and the clock offset as unknowns; Solving the matrix equation to obtain the total ionospheric electrons on the ranging signal path between the master device and the slave device and the clock offset between the master device and the slave device.

4. The time comparison method for two-way pseudorange measurement according to claim 1, characterized in that The a main pseudorange ranging signals and the w slave pseudorange ranging signals satisfying the preset carrier frequency relationship is expressed as: Among them, V represents a real constant, a represents the number of primary pseudorange ranging signals, i represents the number of the primary pseudorange ranging signal, w represents the number of secondary pseudorange ranging signals, j represents the number of the secondary pseudorange ranging signal, f u,j (n) represents the carrier frequency of the secondary pseudorange ranging signal numbered j at the nth moment, f z,i (n) represents the carrier frequency of the primary pseudorange ranging signal numbered i at the nth moment.

5. The time comparison method for two-way pseudorange measurement according to claim 1, characterized in that When the carrier frequencies of the a main pseudorange ranging signals and the carrier frequencies of the w slave pseudorange ranging signals satisfy the preset carrier frequency relationship, the determining the clock offset between the master device and the slave device by using the a main pseudorange ranging values and the w slave pseudorange ranging values includes: Performing correction processing on the a main pseudorange ranging values and the w slave pseudorange ranging values respectively to obtain a corrected main pseudorange ranging values and w corrected slave pseudorange ranging values; Perform mean processing on a corrected primary pseudorange ranging values to obtain an average primary pseudorange ranging value; Perform mean processing on w corrected secondary pseudorange ranging values to obtain an average secondary pseudorange ranging value; Subtract the average secondary pseudorange ranging value from the average primary pseudorange ranging value to determine the clock difference between the master device and the slave device.

6. The time comparison method for two-way pseudorange measurement according to claim 2 or 5, characterized in that The step of respectively performing correction processing on a primary pseudorange ranging values and w secondary pseudorange ranging values further includes: Use the pseudorange ranging expression to represent a primary pseudorange ranging values and w secondary pseudorange ranging values, obtaining the expressions of a primary pseudorange ranging values and the expressions of w secondary pseudorange ranging values; Perform correction processing on the expressions of a primary pseudorange ranging values and the expressions of w secondary pseudorange ranging values respectively.

7. The time comparison method for two-way pseudorange measurement according to claim 6, characterized in that The expression of the primary pseudorange ranging value is: where \(i = 1, 2, \cdots, a\), \(i\) is a positive integer, \(\rho\) z,i (n) represents the main pseudorange ranging value of the \(i\)-th at the \(n\)-th moment, \(R\) true,z,i (n) represents the true space distance that the main pseudorange ranging signal of the \(i\)-th passes through at the \(n\)-th moment; \(I\) z,i (n) represents the ionospheric delay of the main pseudorange ranging signal of the \(i\)-th at the \(n\)-th moment; \(T\) duiliu,z,i (n) represents the tropospheric delay of the main pseudorange ranging signal of the \(i\)-th at the \(n\)-th moment; \(X\) z,i (n) represents the hardware device delay of the main pseudorange ranging signal of the \(i\)-th at the \(n\)-th moment. The pseudorange ranging signal hardware device delay includes the transmission delay of the main pseudorange ranging signal of the \(i\)-th, and the reception delay of the main pseudorange ranging signal of the \(i\)-th; \(c\) represents the speed of light, unit; \(\delta t\) s (n) represents the clock offset of the master device relative to the system time at the \(n\)-th moment; \(\delta t\) z (n) represents the clock offset of the slave device relative to the system time at the \(n\)-th moment, sagnac zz (n) represents the Sagnac effect delay of the main pseudorange ranging signal at the \(n\)-th moment; The expression of the secondary pseudorange ranging value is: where j = 1, 2, ……, w, j is a positive integer, ρ u,j (n) represents the pseudo-range ranging value of the j-th signal at the n-th moment, R true,u,j (n) represents the actual space distance traveled by the pseudo-range ranging signal of the j-th signal at the n-th moment, I u,j (n) represents the ionospheric delay of the pseudo-range ranging signal of the j-th signal at the n-th moment, T duiliu,u,j (n) represents the tropospheric delay of the pseudo-range ranging signal of the j-th signal at the n-th moment, X u,j (n) represents the hardware device delay of the pseudo-range ranging signal of the j-th signal at the n-th moment. The hardware device delay of the pseudo-range ranging signal includes the transmission delay of the pseudo-range ranging signal numbered j and the reception delay of the pseudo-range ranging signal numbered j, sagnac uu (n) represents the Sagnac effect delay of the pseudo-range ranging signal at the n-th moment.

8. The time comparison method for two-way pseudorange measurement according to claim 7, characterized in that, The corrected primary pseudorange ranging value is: where \(i = 1, 2, \cdots, a\), \(i\) is a positive integer; \(\rho\) z,i,a (n) represents the corrected main pseudorange ranging value numbered \(i\); The corrected secondary pseudorange ranging value is: where j = 1, 2, ……, w, j is a positive integer, and ρ u,j,a (n) represents the corrected pseudorange ranging value with the number j.

9. A time comparison system for two-way pseudorange measurement, characterized in that, The system is applied to the time synchronization method for two-way pseudorange measurement according to any one of claims 1-8. The system includes a computing device and a master device and a slave device connected by communication; Wherein, there are a primary pseudorange ranging signals and w secondary pseudorange ranging signals between the master device and the slave device. The a primary pseudorange ranging signals and w secondary pseudorange ranging signals include at least three different carrier frequencies, and a + w ≥ 3; The computing device is respectively connected to the master device and the slave device by communication, and is configured to receive the secondary pseudorange ranging value measured by the master device, the primary pseudorange ranging value measured by the slave device, and determine the total number of electrons in the ionosphere on the ranging signal path between the master device and the slave device and the clock difference between the master device and the slave device.

10. The time comparison system for two-way pseudorange measurement according to claim 9, wherein The master device includes a first pseudorange ranging device, a first time-frequency device and a first pseudorange generating device, and the slave device includes a second pseudorange ranging device, a second time-frequency device and a second pseudorange generating device; The first pseudorange ranging device and the first pseudorange generating device are connected by communication. The first pseudorange ranging device and the first pseudorange generating device are set with zero baseline, and the first pseudorange ranging device and the first pseudorange generating device are respectively connected to the first time-frequency device. The first time-frequency device is configured to provide time-frequency signals to the first pseudorange ranging device and the first pseudorange generating device. The first pseudorange generating device is configured to generate and broadcast the primary pseudorange ranging signal, and the first pseudorange ranging device is configured to receive and measure the secondary pseudorange ranging signal; The second pseudorange ranging device and the second pseudorange generating device are connected by communication. The second pseudorange ranging device and the second pseudorange generating device are set with zero baseline, and the second pseudorange ranging device and the second pseudorange generating device are respectively connected to the second time-frequency device. The second time-frequency device is configured to provide time-frequency signals to the second pseudorange ranging device and the second pseudorange generating device. The second pseudorange generating device is configured to generate and broadcast the secondary pseudorange ranging signal, and the second pseudorange ranging device is configured to receive and measure the primary pseudorange ranging signal.

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