A satellite navigation message monitoring method based on inter-satellite measurement

Abstract

The present invention generally relates to the field of navigation satellite technology, and proposes a satellite navigation message monitoring method based on inter-satellite measurement. The method comprises the following steps: inter-satellite ranging of navigation satellites; and monitoring satellite navigation messages according to the results of inter-satellite ranging, wherein the satellite navigation messages include ephemeris parameters and clock error parameters, wherein monitoring the ephemeris parameters comprises the following steps: calculating a first geometric distance between a first satellite and a second satellite at the current moment according to the ephemeris parameters of the first and second satellites; calculating a second geometric distance between the first satellite and the second satellite at the current moment according to the inter-satellite ranging results of the first and second satellites; and judging the rationality of the ephemeris parameters at the current moment by comparing the first and second geometric distances.

Description

Technical field

[0001] The present invention generally relates to the field of navigation satellite technology. Specifically, the present invention relates to a satellite navigation message monitoring method based on inter-satellite measurement. Background technology

[0002] In navigation satellite systems, since ground control facilities are spread all over the world, the GPS navigation system can monitor the health status of GPS navigation satellites around the world in real time and deal with and recover the faults in a timely manner, thereby ensuring the continuity of navigation services of the GPS navigation system.

[0003] Beidou satellite navigation system is a global satellite navigation system that operates independently in my country. When the Beidou satellite has a navigation signal failure due to single-particle space effect or interference confrontation factors overseas, the navigation signal can only be set to unavailable first, and wait until the Beidou satellite enters the country again before disposing and restoring it. This will Directly affects the continuity and availability of navigation services provided by Beidou satellite. Therefore, it is necessary to conduct autonomous integrity monitoring of satellite navigation signals.

[0004] Satellite navigation message is a very important type in satellite navigation signals. Satellite navigation message is broadcast to users by navigation satellites, which can describe the operating status parameters of the navigation satellite. The operating status parameters can include system time, ephemeris, almanac, Satellite clock correction parameters, navigation satellite health status, and ionosphere delay model parameters. The operating status parameters can provide the user with time information, and the position coordinates and speed of the navigation satellite can be calculated using the operating status parameters, and the user can calculate its own position coordinates and speed through multi-star positioning. Therefore, Beidou satellite can independently verify the satellite navigation message in the space section to make up for the shortcomings of the Beidou satellite navigation system without global monitoring stations, and can also restore the normal services of navigation satellites with navigation signal failures more quickly.

[0005] At present, the validity time of each group of satellite navigation messages is usually 1 hour. Since the satellite navigation messages have a certain time gap from generation to actual broadcasting, the next hour's message can be checked in advance to ensure that On the premise that the one-hour message is reasonable and effective, the previous hour message can be used to verify the rationality of the next hour message parameters and realize advance monitoring of the upcoming satellite navigation message.

[0006] However, the advance monitoring of satellite navigation messages is only a one-time monitoring before the broadcast of the message occurs. If during the encoding and broadcasting of the satellite navigation messages, such as single-particle overturning of the source of the message, the parameter error will be caused. These errors will not be monitored. Contents of invention

[0007] To at least partially solve the above-mentioned problems in the prior art, the present invention proposes a satellite navigation message monitoring method based on inter-satellite measurement, including:

[0008] conduct inter-satellite distance measurement on navigation satellites; and

[0009] According to the results of inter-star ranging, the satellite navigation message includes ephemeris parameters and clock difference parameters, and monitoring the ephemeris parameters includes the following steps:

[0010] The first geometric distance between the first satellite and the second satellite at the current moment is calculated based on the ephemeris parameters of the first and second satellites;

[0011] Based on the inter-star ranging results of the first and second satellites, the second geometric distance between the first satellite and the second satellite at the current time is calculated; and

[0012] By comparing the first and second geometric distances, the rationality of the ephemeris parameters at the current time is judged.

[0013] In one embodiment of the present invention, the first and second satellites broadcast satellite navigation messages and the first satellite establishes inter-satellite links with the second satellite for ranging, respectively, as a transmitting end and a receiving end; in

[0014] The moments at which the first and second satellites broadcast satellite navigation messages closest to the current time T0 are expressed as the first time T1 and the second time T2, respectively;

[0015] The message transmission time when the first satellite closest to the current time T0 is represented as the third time T3 when the first satellite is closest to the current time T0 as the transmitter to establish an inter-satellite link with the second satellite to complete distance measurement; and

[0016] The message transmission time when the first satellite closest to the current time T0 is established as a receiver and the second satellite to complete distance measurement is represented as the fourth time T4.

[0017] In one embodiment of the present invention, it is provided that the time interval between the initial time and the first to fourth time is less than or equal to 1 minute.

[0018] In one embodiment of the present invention, it is stipulated that the ephemeris parameters in the satellite navigation message broadcasted by the first time T1 and the ephemeris parameters in the satellite navigation message broadcasted by the second time T2 are used to perform the ephemeris parameters in the satellite navigation message broadcasted by the second time T2. Orbit extrapolation is used to calculate the positions of the first satellite and the second satellite at the current time, and to calculate the first geometric distance between the first satellite and the second satellite at the current time.

[0019] In one embodiment of the present invention, it is stipulated that the first satellite and the second satellite are calculated at the current time based on the inter-satellite link distance measurement results between the first satellite and the second satellite at the third time T3 and the fourth time T4. The second geometric distance between.

[0020] In one embodiment of the present invention, it is provided that a geometric distance difference threshold value is provided, wherein when the difference between the first geometric distance and the second geometric distance is greater than the geometric distance difference threshold value, the current time star is determined An exception occurred in the calendar parameter.

[0021] In one embodiment of the present invention, monitoring the clock difference parameter includes the following steps:

[0022] The first clock difference value between the first satellite and the second satellite at the current time is calculated based on the clock difference parameters of the first and second satellites;

[0023] Based on the inter-star ranging results of the first and second satellites, the second clock difference value between the first satellite and the second satellite at the current time is calculated; and

[0024] The rationality of the current time-hour difference parameter is judged by comparing the first and second geometric distances.

[0025] In one embodiment of the present invention, it is stipulated that the clock difference parameter in the satellite navigation message broadcasted by the first time T1 and the clock difference parameter in the satellite navigation message broadcasted by the second time T2 are calculated. The clock difference between the first satellite and the second satellite at the current time is calculated, and the first clock difference difference between the first satellite and the second satellite at the current time is calculated.

[0026] In one embodiment of the present invention, it is stipulated that the first satellite and the second satellite are calculated at the current time based on the inter-satellite link distance measurement results between the first satellite and the second satellite at the third time T3 and the fourth time T4. The difference between the second clock.

[0027] In one embodiment of the invention, it is provided that a clock difference difference threshold value is provided, wherein when the difference between the first clock difference value and the second clock difference value is greater than the clock difference difference threshold value, Determines that the current clock difference parameter has an abnormality.

[0028] The present invention has at least the following beneficial effects: The present invention proposes a satellite navigation message monitoring method based on inter-star measurement, which can monitor the ephemeris parameters and clock difference parameters of the navigation satellite, and can broadcast the ephemeris clock difference of the satellite. Make real-time judgments on the rationality of parameters to avoid satellite broadcasts incorrect telegram parameters. This method is suitable for avoiding possible errors that may occur during the generation, transmission and broadcast of ground operation and control systems and satellite systems in the entire process of message generation, transmission and propagation.

[0029] In the technical solution of the present invention, by using extraorbital arithmetic algorithm, algorithm defined based on the clock difference parameter itself, inter-star link measurement model, range epoch-reduction calculation and other algorithms, combined with the characteristics of the satellite navigation message itself, it is possible to use the algorithm for the use of algorithms defined based on the clock difference parameter itself, the inter-star link measurement model can be used for the calculation of the calculation of the satellite navigation message itself. The data is subject to dimensionality reduction processing, and can convert complex ephemeris parameters and clock difference parameters into one-dimensional threshold value interpretation, which is simple and effective; the method of the present invention provides a real-time monitoring possibility of minute orders, satisfying the rapid and real-time satellites. The monitoring requirement also provides ideas and solutions for the expansion of the on-star integrity monitoring capability; and the method of the present invention is suitable for uplink injection link failure, does not rely on the control of the ground station, and can realize independent judgment in the constellation , can effectively reduce the unplanned interruption indicators of satellites. Attached description of the drawings

[0030] To further clarify the advantages and features of the embodiments of the invention, a more specific description of the embodiments of the invention will be presented with reference to the accompanying drawings. It is to be understood that these drawings depict only typical embodiments of the invention and will therefore not be considered as limiting of its scope. In the drawings, for clarity, the same or corresponding components will be denoted by the same or similar numerals.

[0031] Figure 1 A schematic diagram of a navigation satellite establishing an inter-satellite link in one embodiment of the present invention is shown.

[0032] Figure 2 A flow diagram for monitoring the ephemeris parameters of satellite navigation messages in one embodiment of the present invention is shown.

[0033] Figure 3 A flow diagram for monitoring the clock difference parameters of satellite navigation messages in one embodiment of the present invention is shown. Specific implementation methods

[0034] It should be noted that the components in the drawings may be exaggerated for illustration and are not necessarily proportionally correct. In each of the drawings, components with the same or functionally identical are provided with the same reference numerals.

[0035] In the present invention, unless otherwise specified, “arranged on”, “arranged above” and “arranged above” do not exclude the existence of an intermediate between the two. In addition, "arranged on or above" only represents the relative positional relationship between the two components, and in certain cases, if the product direction is reversed, it can also be converted to "arranged on or below" and vice versa Of course.

[0036] In the present invention, the embodiments are intended only to illustrate the aspects of the invention and should not be construed as limiting.

[0037] In the present invention, unless otherwise specified, the quantifiers "one" and "one" do not exclude scenes of multiple elements.

[0038] It should also be noted here that in embodiments of the invention, only a portion of the components or components may be shown for clarity and simplicity, but those skilled in the art will appreciate that under the teachings of the invention, it may be based on the specificity. The scene needs to add the required parts or components. In addition, unless otherwise specified, the features in different embodiments of the invention may be combined with each other. For example, the corresponding or functionally identical or similar features in the first embodiment can be replaced by a feature in the second embodiment, and the resulting embodiments also fall within the scope of the disclosure or description of the present application.

[0039] It should also be noted here that within the scope of the present invention, the words "same", "equal", "equal", etc. do not mean that the values ​​of the two are absolutely equal, but allow certain reasonable errors, that is, the The wording also covers "basically the same", "basically the same", and "basically the same". By analogy, in the present invention, the terms "perpendicular to", "parallel to", etc. of the direction also cover the meanings of "substantially perpendicular to", "substantially parallel to".

[0040] In addition, the number of steps of each method of the present invention does not define the order of execution of the steps of the method. Unless otherwise specified, the method steps may be performed in different orders.

[0041] The present invention will be further explained below in connection with specific embodiments with reference to the accompanying drawings.

[0042] The present invention proposes a satellite navigation message monitoring method based on inter-satellite measurement. Through this method, the navigation satellite can independently use the limited data resources on the satellite to monitor satellite navigation message, and realize the rational judgment of autonomous message parameters, which can It includes two parts: advance monitoring and real-time monitoring. Early monitoring can monitor the rationality of the telegram parameters that will be broadcasted in the next hour before the satellite navigation message is updated every hour; real-time monitoring can conduct reasonable detection of the telegram parameters that are being broadcasted during the broadcast of the satellite navigation message of this hour. .

[0043] The message parameters can include ephemeris parameters and clock difference parameters. In the process of monitoring ephemeris parameters and clock difference parameters, it is meaningless to make a simple threshold judgment on a single parameter, so the latest ephemeris needs to be used. The multi-dimensional parameters composed of telegram parameters and clock difference parameters are dimensionally reduced, and a set of one-dimensional results are obtained. Finally, a reasonable error threshold value is set according to the engineering requirements to determine the rationality of telegram parameters.

[0044] The invention is based on the inventor's insight that navigation satellites can receive the latest ephemeris and clock difference parameters injected by the ground system every hour. Among them, the ephemeris parameters can reflect the position status of the navigation satellite. Since the navigation satellite usually operates stably at a certain orbit and speed, the location of the navigation satellite is located has a certain predictability, and extrapolation prediction can be performed based on the ephemeris parameters. The clock difference parameter can reflect the offset of the satellite clock of the navigation satellite relative to the ground clock. Since the star-ground atomic clock has stable characteristics during stable operation, the clock difference parameter usually does not change significantly.

[0045] Since satellite ephemeris and clock difference parameters are system parameters composed of multiple parameters, it is impossible to directly compare and judge through a single parameter. Therefore, in order to ensure the correctness of satellite ephemeris and clock difference parameters injection and broadcast, in the method of the present invention, it is possible to Using the above characteristics of the ephemeris parameters and clock difference parameters, the ephemeris parameters to be broadcasted on the star are converted into the orbital position of the satellite and the clock difference parameters to be broadcasted on the star are converted into the time change information of the clock clock, and then the parameters are reasonable. Sexual judgment.

[0046] The following will describe the following in detail the process of judging ephemeris parameters and clock difference parameters by satellite navigation message monitoring method based on inter-star measurement in one embodiment of the present invention in conjunction with the accompanying drawings.

[0047] Figure 1 A schematic diagram of a navigation satellite performing inter-satellite measurement in one embodiment of the present invention is shown. like Figure 1 As shown, satellite A may be a satellite to be evaluated, where satellite A and satellite B store the currently being broadcasted message parameters in real time, and store the received ranging information and message parameter information obtained from the link building with other navigation satellites in real time.

[0048] The current moment is represented as T0 time. The satellite that has recently established a chain between satellite A is satellite B. The reference times of the recently broadcasted telegrams of the stored dual stars are T1 and T2 respectively. Satellite A has recently established a chain between satellite B as the sending end, and satellite B, and completed The distance measurement and message transmission time is T3. Satellite A has recently established a link with Satellite B as the receiver, and the distance measurement and message transmission time is T4. (The actual time interval between T0 and T4 of satellite is ≤1 minute.)

[0049] At T0 time, satellite A can retrieve the stored T2 time satellite B message parameters, T3 time inter-star link distance measurement value, T4 time inter-star link distance measurement value, and T0 time telegram parameters that satellite A is broadcasting. Based on this, satellite A can conduct real-time monitoring and rational judgment on satellite ephemeris parameters and satellite clock difference parameters.

[0050] Figure 2 A flow diagram of a navigation satellite performing real-time monitoring of satellite ephemeris parameters based on inter-satellite measurements is shown in one embodiment of the present invention. Among them, the ephemeris parameters can describe the satellite orbit obtained at a certain fitting interval, and the ephemeris parameters include 18 quasi-Kepler orbit parameters and 1 satellite orbit type parameter. Under normal circumstances, the update period of the ephemeris parameters is 1 hour, and it is updated at an hour during Beidou time (BDT, Beidou Time).

[0051] like Figure 2 As shown, satellite A can uniformly calculate the geometric distance X1 of satellite A-B at a certain time T0 based on the ephemeris parameters broadcasted by itself and the ephemeris parameters received by satellite B through orbit extrapolation; further, satellite A can be based on The inter-star distance measurement is calculated through the inter-star link measurement model and the distance measurement epoch, and is uniformly calculated to the geometric distance X2 between satellite A and satellite B at a certain time; and the difference between the two X1 and X2 can be compared. , you can set thresholds based on engineering experience to judge the correctness of ephemeris parameters.

[0052] Specifically, the navigation satellite can conduct real-time monitoring of satellite ephemeris parameters based on inter-star measurements and make reasonable judgments on ephemeris parameters.

[0053] Step 1: Obtain the ephemeris parameters of this ephemeris being broadcasted by a set of satellite A (ephemeris parameter array 1). Take the ephemeris parameters of the B1C signal as an example. The ephemeris parameters include 19 parameters;

[0054] Step 2: Obtain the latest ephemeris parameters of a set of satellite B (ephemeris parameter array 2). Taking the ephemeris parameters broadcast by B1C signal as an example, the ephemeris parameters include 19 parameters;

[0055] Step 3: Obtain the latest bidirectional ranging results of a set of satellites A-B, and record the corresponding ranging times T3 and T4;

[0056] Step 4: Take the current time T0 as the reference time, and according to the extraorbital algorithm, calculate the satellite A position O at the time T0 according to the ephemeris parameter array 1 and ephemeris parameter array 2 respectively. 1 (X k1 , Y k1 ,Z k1 ) and satellite B position O 2 (X k1 , Y k1 ,Z k1 ), calculate the distance X1 of the positions of the two satellites, that is

[0057] Step 5: Satellite A can calculate the latest bidirectional distance measurement results of satellite A-B at T3 and T4 times according to the inter-star link measurement model and ranging epoch, and calculate the latest bidirectional distance measurement results of satellite A-B at the current time T0 and deduct the distance measurement error. The geometric distance X2 between satellite A and satellite B obtained after clock difference error;

[0058] Step 6: Set the threshold threshold based on engineering data experience. If |X1-X2| exceeds the threshold, it is determined that the message parameters are abnormal, otherwise it is determined that the message parameters are reasonable.

[0059] Figure 3 A real-time monitoring method for satellite clock difference parameters based on inter-satellite measurements is shown in one embodiment of the present invention. The clock difference parameter may include t oc , a 0 , a 1 , a 2 . t oc It is the reference time of this clock difference parameter, in seconds. Under normal circumstances, the update period of the clock difference parameter is 1 hour and is updated at the hour of BDT.

[0060] like Figure 3 It is shown that satellite A can uniformly calculate the clock difference of T0 at a certain time based on the clock difference message transmitted by itself and the received satellite B clock difference message, and obtain the clock difference Y1 between satellite A and satellite B; further, Satellite A can calculate the inter-star link measurement model and the distance measurement epoch according to the inter-star distance measurement, and uniformly calculate the clock difference between satellite A and satellite B at a certain time; and the two Y1 and Y2 can be compared. The difference value can be set according to the engineering requirements to determine the correctness of the clock difference parameter.

[0061] Specifically, the navigation satellite can conduct real-time monitoring of satellite clock difference parameters based on inter-satellite measurements and make reasonable judgments on ephemeris parameters.

[0062] Step 1: Obtain the clock difference parameters (clock difference parameter array 1) that a set of satellite A is broadcasting. Taking the ephemeris parameters of B1C signal as an example, the clock difference parameters include 4 parameters;

[0063] Step 2: Obtain the latest clock difference parameters of a set of satellite B (clock difference parameter array 2). Taking the ephemeris parameters of B1C signal broadcast as an example, the clock difference parameters include 4 parameters;

[0064] Step 3: Obtain the latest bidirectional ranging results of a set of satellites A-B, and record the corresponding ranging times T3 and T4;

[0065] Step 4: Take the current time T0 as the reference time, and according to the clock difference parameter definition, calculate the satellite A clock difference A at T0 time according to the clock difference parameter array 1 and clock difference parameter array 2 respectively. 1 A difference between satellite B 2 , calculate the clock difference Y1 between satellite A and satellite B, that is, Y1 = A1-A2;

[0066] Step 5: Satellite A can calculate the latest bidirectional distance measurement results of satellite A-B at T3 and T4 times according to the inter-star link measurement model and ranging epoch, and calculate the latest bidirectional distance measurement results of satellite A-B at the moments T3 and T4 to the current time T0 and deduct the distance measurement and measurement. The clock difference Y2 between satellite A and satellite B obtained after the distance error;

[0067] Step 6: Set the threshold threshold based on the experience of engineering data. If |Y1-Y2| exceeds the threshold, it is determined that the clock difference parameter is abnormal, otherwise it is determined that the clock difference parameter is reasonable.

[0068] Although various embodiments of the invention have been described above, it should be understood that they are presented by example only and are not intended to be limiting. It will be apparent to those skilled in the relevant art that various combinations, variations and changes can be made thereto without departing from the spirit and scope of the invention. Therefore, the width and scope of the invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined only in accordance with the appended claims and their equivalents.

Claims

1. A satellite navigation message monitoring method based on inter-satellite measurement, characterized in that: The following steps are involved: Conduct inter-satellite ranging for navigation satellites; as well as The satellite navigation message is monitored according to the result of the inter-satellite ranging, wherein the satellite navigation message includes ephemeris parameters and clock error parameters, wherein the monitoring of the ephemeris parameters includes the following steps: Calculate a first geometric distance between the first satellite and the second satellite at a current time according to the ephemeris parameters of the first and second satellites; Calculate a second geometric distance between the first satellite and the second satellite at the current moment according to the inter-satellite ranging results of the first and second satellites; as well as By comparing the first and second geometric distances, the rationality of the ephemeris parameters at the current moment is determined; The first and second satellites broadcast satellite navigation messages and the first satellite acts as a transmitter and a receiver respectively to establish an intersatellite link with the second satellite for ranging; in The times when the first and second satellites, which are closest to the current time T0, broadcast satellite navigation messages are represented as the first time T1 and the second time T2 respectively; The time when the first satellite closest to the current time T0 is used as a transmitter to establish an intersatellite link with the second satellite to complete ranging is expressed as a third time T3; as well as The time of message transmission when the first satellite closest to the current time T0 is used as a receiving end to establish an intersatellite link with the second satellite to complete ranging is expressed as a fourth time T4; Wherein the ephemeris parameters in the satellite navigation message broadcast by the first satellite at the first time T1 and the ephemeris parameters in the satellite navigation message broadcast by the second satellite at the second time T2 are used to perform orbit extrapolation to calculate the positions of the first satellite and the second satellite at the current time, and calculate the first geometric distance between the first satellite and the second satellite at the current time; Calculate a second geometric distance between the first satellite and the second satellite at a current moment according to the inter-satellite link ranging result between the first satellite and the second satellite at a third moment T3 and a fourth moment T4; A geometric distance difference threshold is provided, wherein when the difference between the first geometric distance and the second geometric distance is greater than the geometric distance difference threshold, it is determined that an abnormality occurs in the ephemeris parameter at the current moment.

2. The satellite navigation message monitoring method based on inter-satellite measurement according to claim 1 is characterized in that: The time interval between the initial moment and the first to fourth moments is less than or equal to 1 minute.

3. The satellite navigation message monitoring method based on inter-satellite measurement according to claim 1 is characterized in that: Monitoring the clock error parameters comprises the following steps: Calculate a first clock difference between the first satellite and the second satellite at the current moment according to the clock difference parameters of the first and second satellites; Calculate a second clock difference between the first satellite and the second satellite at the current moment according to the inter-satellite ranging results of the first and second satellites; as well as The rationality of the clock error parameter at the current time is determined by comparing the first and second geometric distances.

4. The satellite navigation message monitoring method based on inter-satellite measurement according to claim 3 is characterized in that: The clock difference between the first satellite and the second satellite at the current moment is calculated using the clock difference parameters in the satellite navigation message broadcast by the first satellite at the first moment T1 and the clock difference parameters in the satellite navigation message broadcast by the second satellite at the second moment T2, and the first clock difference between the first satellite and the second satellite at the current moment is calculated.

5. The satellite navigation message monitoring method based on inter-satellite measurement according to claim 4 is characterized in that: The second clock difference between the first satellite and the second satellite at the current moment is calculated according to the inter-satellite link ranging results between the first satellite and the second satellite at the third moment T3 and the fourth moment T4.

6. The satellite navigation message monitoring method based on inter-satellite measurement according to claim 5 is characterized in that: A clock difference threshold is provided, wherein when the difference between the first clock difference and the second clock difference is greater than the clock difference threshold, it is determined that the clock difference parameter at the current moment is abnormal.

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