A method for detecting the longest continuous complete arc segment for post-orbit determination and timing of low-orbit satellites

Abstract

The present invention discloses a method for detecting the longest continuous complete arc segment for post-orbit determination and timing of low-orbit satellites, and belongs to the field of satellite positioning and timing. Based on the possibly incomplete and discontinuous onboard GNSS observations of low-orbit satellites, in the post-orbit determination and timing processing, the present invention detects the continuity and completeness of the onboard GNSS observations of low-orbit satellites, avoids the long discontinuous parts, and automatically searches for the longest continuous complete arc segment in a given arc segment for orbit determination and timing, thereby avoiding manual search, making full use of data with good continuity and completeness, and abandoning some data with poor continuity and completeness, thereby performing high-precision low-orbit satellite orbit determination and timing without wasting existing observations and sacrificing accuracy, avoiding accuracy problems caused by data quality problems in direct orbit determination and timing, and avoiding waste of effective observations caused by abandoning this round of orbit determination and timing due to error reporting and failure to pass self-check.

Description

Technical Field

[0001] The invention belongs to the field of satellite positioning and timing, and in particular relates to a method for detecting the longest continuous complete arc segment of post-orbit determination and timing of a low-orbit satellite. Background Art

[0002] Thanks to the low altitude, high speed and low cost of low-orbit satellites, low-orbit enhanced GNSS (Global Navigation Satellite System) positioning, navigation and timing have a series of advantages such as strong signal strength, short convergence time and whitening of multipath effects, and have received more and more attention in recent years. In order to better utilize low-orbit navigation signals to achieve high-precision real-time positioning and timing on the ground, high-precision real-time orbit star clock products of low-orbit satellites have become an important prerequisite and the key to determining the accuracy of future low-orbit enhanced GNSS ground positioning, navigation and timing.

[0003] The current post-orbit determination and timing of low-orbit satellites often directly use onboard GNSS observations after a given arc start time and arc length, and perform orbit determination and timing processing based on the batch least squares method and the corresponding dynamic model. However, if there are incomplete or discontinuous observations in a given orbit determination and timing arc (such as a few hours of interruption in the tail), it will affect the accuracy and integrity of the orbit determination and timing. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0005] A method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite, comprising:

[0006] S1, according to the name of the target low-orbit satellite to be detected, the orbit determination arc length, the arc segment start time point, the detection sampling interval and the set of GNSS systems to be detected, detect the systems existing in the observation arc segment determined by the arc segment start time point and the orbit determination arc length of the target low-orbit satellite to obtain the set of existing systems;

[0007] S2, based on the existing system set, the input orbit determination arc length, and the arc segment start time point, detect the continuity and integrity of the latest updated arc segment in the onboard GNSS observation of the target low-orbit satellite, determine the valid epoch and the valid arc segment, and thus obtain the valid arc length, integrity, longest interruption, the first epoch within the longest interruption, and the last epoch within the longest interruption;

[0008] S3, judging whether the current valid arc segment meets the preset requirements for the integrity and continuity of the spaceborne GNSS observation according to the current valid arc length, integrity and longest discontinuity;

[0009] S4, if the preset requirement is met, determining that the current valid arc segment is the longest continuous complete arc segment detected;

[0010] S5, if the preset requirement is not met, determining the longer arc segment of the remaining first and last arc segments in the current valid arc segment, except for the arc segment corresponding to the longest discontinuity;

[0011] S6, when the longer arc segment is greater than the shortest valid arc length threshold, using the longer arc segment to update the orbit determination arc length and the arc segment start time point, and returning to S2 for re-detection;

[0012] S7: When the longer arc segment is less than or equal to the shortest valid arc length threshold, it is determined that the longest continuous complete arc segment cannot be found, and orbit determination is abandoned.

[0013] Beneficial effects of the present invention:

[0014] Based on the possibly incomplete and discontinuous low-orbit satellite onboard GNSS observations, in the post-orbit determination and timing processing, the longest continuous complete arc segment detection method for post-orbit determination and timing of low-orbit satellites provided by the embodiment of the present invention detects the continuity and completeness of the low-orbit satellite onboard GNSS observations, avoids long discontinuous parts, and automatically searches for the longest continuous complete arc segment in a given arc segment for orbit determination and timing, thereby avoiding manual search, making full use of data with good continuity and completeness, and abandoning some data with poor continuity and completeness, thereby performing high-precision low-orbit satellite orbit determination and timing without wasting existing observations and without sacrificing accuracy, avoiding accuracy problems caused by direct orbit determination and timing due to data quality problems, and avoiding waste of effective observations caused by abandoning this round of orbit determination and timing due to errors or failure of self-checking. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic flow chart of a method for detecting the longest continuous complete arc segment for post-orbit determination and timing of a low-orbit satellite provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0017] The embodiment of the present invention provides a method for detecting the longest continuous complete arc segment for post-orbit determination and timing of a low-orbit satellite based on batch least squares simplified dynamic post-orbit determination and timing after the onboard GNSS observation data is transmitted back to the ground, and orbit determination can be achieved based on the detected longest continuous complete arc segment.

[0018] This method is used for ground data processing, such as Figure 1 As shown, the following steps may be included:

[0019] S1, according to the name of the target low-orbit satellite to be detected, the orbit determination arc length, the arc segment start time point, the detection sampling interval and the set of GNSS systems to be detected, detect the systems existing in the observation arc segment determined by the arc segment start time point and the orbit determination arc length of the target low-orbit satellite to obtain the set of existing systems;

[0020] The implementation basis of the present invention is that the onboard GNSS observation data of the target low-orbit satellite to be detected has been obtained.

[0021] Among them, S1 may include the following processes:

[0022] According to the name of the target low-orbit satellite to be detected, the orbit determination arc length, the arc segment start time point, and the detection sampling interval, each system in the GNSS system set to be detected is detected one by one within the observation arc segment determined by the arc segment start time point and the orbit determination arc length. For the detected system, if an epoch of the system containing dual-frequency observation of at least 4 satellites is found, it is determined that the system exists, so that after all systems are detected, the set of existing systems is obtained.

[0023] Specifically, the embodiment of the present invention can execute the method for detecting the longest continuous complete arc segment of post-orbit determination timing of the low-orbit satellite for each target low-orbit satellite to be detected.

[0024] First, enter the name of the target low-orbit satellite {sat}, orbit determination arc length {TALL}, arc segment start time point {epo}, sampling interval of detection {samp} and the set of GNSS systems to be detected {sys}: the set of GNSS systems to be detected {sys} contains multiple GNSS systems, which have been sorted according to predefined rules. Represents a variable, such as a refers to the variable a, and {} are brackets.

[0025] Then, for the observation arc segment determined by the arc segment start time point and the orbit determination arc length, the start point is the arc segment start time point, and the end point is the sum of the arc segment start time point and the orbit determination arc length, which is expressed as [ {epo}, {epo}+ {TALL}], within the observation arc, for the set of GNSS systems to be detected Each system in {sys} is detected one by one. If an epoch containing at least 4 satellites with dual-frequency observation is found, the system is considered to exist. After all systems in {sys} are detected, the existing system set is obtained {allsys} represents the set of GNSS systems existing in the above observation arc.

[0026] Among them, for For each GNSS system in {sys}, the frequency band of dual-frequency observation is pre-defined. For example, for the GPS (Global Positioning System) system, the frequency band of dual-frequency observation can be defined as L1 is 1575.42 MHz and L2 is 1227.6 MHz. The frequency bands of dual-frequency observation of other GNSS systems are not described here.

[0027] S2, based on the existing system set, the input orbit determination arc length, and the arc segment start time point, detect the continuity and integrity of the latest updated arc segment in the onboard GNSS observation of the target low-orbit satellite, determine the valid epoch and the valid arc segment, and thus obtain the valid arc length, integrity, longest interruption, the first epoch within the longest interruption, and the last epoch within the longest interruption;

[0028] This step is to detect the integrity and continuity of the latest updated arc segment of the space-borne GNSS observation, and obtain the detection results at one time using all systems in the existing system set. S2 may include the following steps:

[0029] 1) According to the name of the target low-orbit satellite and the sampling interval of the detection, within the observation arc determined by the input arc start time point and the orbit determination arc length, find all epochs containing at least 4 satellites with dual-frequency observations of each system in the system set, and define the found epochs as valid epochs;

[0030] That is, each system in the system set must find the epoch of at least 4 satellites observed by dual frequency to be considered a valid epoch.

[0031] The starting point of the observed arc segment in this step is the starting time point of the arc segment given at this time, and the ending point is the sum of the starting time point of the arc segment given at this time and the orbit determination arc length.

[0032] 2) The orbit determination arc segment from the first valid epoch to the last valid epoch is defined as a valid arc segment, its arc length is determined as the valid arc length, and the time of the first valid epoch is output as the start time of the valid arc segment;

[0033] The effective arc length is {TALL_valid} indicates that the time of the first valid epoch can include {YEAR} (year), {DOY} (Days per Year), {sec} (seconds per day).

[0034] 3) Divide the number of valid epochs in the valid arc by the expected number of epochs to obtain a percentage as the completeness;

[0035] The expected epoch number is obtained based on the input orbit determination arc length and sampling interval; for example, if the orbit determination arc length is 24 hours and the sampling interval is 30 seconds, then the expected epoch number is (24×60×60)÷30=2880.

[0036] Completeness {ava} means, {ava}=(number of valid epochs in the valid arc / number of expected epochs)×100%.

[0037] 4) The longest arc length without a valid epoch in the valid arc is determined as the longest discontinuity, and the first epoch and the last epoch in the longest discontinuity are determined.

[0038] Among them, the longest interruption {gap} indicates that the first epoch in the longest gap is {epo_break0} indicates that the last epoch in the longest break is {epo_break1} indicates.

[0039] The above-mentioned effective arc length, integrity, longest interruption, first epoch within the longest interruption, and last epoch within the longest interruption are used as the detection results of the continuity and integrity of the latest updated arc segment in the onboard GNSS observation of the target low-orbit satellite.

[0040] S3, judging whether the current valid arc segment meets the preset requirements for the integrity and continuity of the spaceborne GNSS observation according to the current valid arc length, integrity and longest discontinuity;

[0041] Among them, S3 includes:

[0042] The three parameters of the current valid arc length, integrity and longest interruption are compared with the corresponding thresholds to determine whether the corresponding parameters meet the standards. When any of the parameters does not meet the standards, it is determined that the current valid arc segment does not meet the preset requirements for the integrity and continuity of the onboard GNSS observations. When all parameters meet the standards, it is determined that the current valid arc segment meets the preset requirements.

[0043] Specifically, the current effective arc length {TALL_valid} is compared with the corresponding threshold. If {TALL_valid} is greater than the corresponding threshold, indicating that the parameter {TALL_valid} met the target;

[0044] The current completeness {ava} is compared with the corresponding threshold. If {ava} is greater than the corresponding threshold, indicating that the parameter {ava} meet the standard;

[0045] The current longest break {gap} is compared with the corresponding threshold. If {gap} is less than the corresponding threshold, indicating that the parameter {gap} meet the target;

[0046] In this step, the thresholds corresponding to the three parameters of effective arc length, completeness and longest discontinuity are preset based on empirical values.

[0047] S4, if the preset requirement is met, determining that the current valid arc segment is the longest continuous complete arc segment detected;

[0048] If the preset requirements are met, the current valid arc segment is determined to be the longest continuous complete arc segment detected, and the detection is completed. The longest continuous complete arc segment detected can be used for orbit determination, and the orbit determination method is batch least squares simplified dynamics post-hoc orbit determination.

[0049] S5, if the preset requirement is not met, determine the longer arc segment of the remaining first and last arc segments in the current valid arc segment, except for the arc segment corresponding to the longest discontinuity.

[0050] This step specifically includes:

[0051] 1) Calculate the arc length from the first epoch of the current valid arc to the epoch before the first epoch of the longest discontinuity as the first arc length;

[0052] 2) Calculate the arc length from the epoch after the last epoch of the longest discontinuity to the last epoch of the current valid arc as the second arc length;

[0053] 3) Select the longer one between the first arc length and the second arc length, and define the arc as the longer arc.

[0054] Specifically, calculate the current valid arc segment from the first epoch to {epo_break0} The length of the arc segment in the previous epoch {TALL_break0}, and, calculate {epo_break1} The arc length from the next epoch to the end epoch of the current valid arc {TALL_break1}; in {TALL_break0} and Select a longer segment from {TALL_break1} and define it as the longer arc segment {TALL_break};

[0055] S6, when the arc length of the longer arc segment is greater than the shortest valid arc length threshold, using the longer arc segment to update the orbit determination arc length and the arc segment start time point, and returning to S2 for re-detection;

[0056] The shortest effective arc length threshold is preset based on empirical values.

[0057] if If the arc length of {TALL_break} is greater than the shortest valid arc length threshold, the longer arc segment is used. {TALL_break} Update orbit determination arc length {TALL}, arc segment start time point {epo}, and then return to S2 to re-detect, wherein the use of the longer arc segment to update the orbit determination arc length and the arc segment start time point means that the start time point of the longer arc segment is used as the updated arc segment start time point, and the arc length of the longer arc segment is used as the updated orbit determination arc length.

[0058] S7: When the arc length of the longer arc segment is less than or equal to the shortest valid arc length threshold, it is determined that the longest continuous complete arc segment cannot be found, and orbit determination is abandoned.

[0059] if If the arc length of {TALL_break} is less than or equal to the shortest valid arc length threshold, it means that the longest continuous complete arc segment cannot be found, and the orbit determination is abandoned, and the process ends.

[0060] Specifically, if the valid arc segment found during the detection process can meet the preset requirements for the integrity and continuity of the onboard GNSS observation, the valid arc segment is determined as the longest continuous complete arc segment detected; if the loop detection is completed until If the arc length of {TALL_break} is less than or equal to the shortest valid arc length threshold and still fails to meet the preset requirement, it means that the longest continuous complete arc segment cannot be found, and the orbit determination is abandoned, and the process ends.

[0061] Based on the possibly incomplete and discontinuous low-orbit satellite onboard GNSS observations, in the post-orbit determination and timing processing, the longest continuous complete arc segment detection method for post-orbit determination and timing of low-orbit satellites provided by the embodiment of the present invention detects the continuity and completeness of the low-orbit satellite onboard GNSS observations, avoids long discontinuous parts, and automatically searches for the longest continuous complete arc segment in a given arc segment for orbit determination and timing, thereby avoiding manual search, making full use of data with good continuity and completeness, and abandoning some data with poor continuity and completeness, thereby performing high-precision low-orbit satellite orbit determination and timing without wasting existing observations and without sacrificing accuracy, avoiding accuracy problems caused by direct orbit determination and timing due to data quality problems, and avoiding waste of effective observations caused by abandoning this round of orbit determination and timing due to errors or failure of self-checking.

[0062] It should be noted that, in the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite, characterized in that: include: S1, according to the name of the target low-orbit satellite to be detected, the orbit determination arc length, the arc segment start time point, the detection sampling interval and the set of GNSS systems to be detected, detect the systems existing in the observation arc segment determined by the arc segment start time point and the orbit determination arc length of the target low-orbit satellite to obtain the set of existing systems; S2, based on the existing system set, the input orbit determination arc length, and the arc segment start time point, detect the continuity and integrity of the latest updated arc segment in the onboard GNSS observation of the target low-orbit satellite, determine the valid epoch and the valid arc segment, and thus obtain the valid arc length, integrity, longest interruption, the first epoch within the longest interruption, and the last epoch within the longest interruption; S3, judging whether the current valid arc segment meets the preset requirements for the integrity and continuity of the spaceborne GNSS observation according to the current valid arc length, integrity and longest discontinuity; S4, if the preset requirement is met, determining that the current valid arc segment is the longest continuous complete arc segment detected; S5, if the preset requirement is not met, determining the longer arc segment of the remaining first and last arc segments in the current valid arc segment, except for the arc segment corresponding to the longest discontinuity; S6, when the arc length of the longer arc segment is greater than the shortest valid arc length threshold, using the longer arc segment to update the orbit determination arc length and the arc segment start time point, and returning to S2 for re-detection; S7: When the arc length of the longer arc segment is less than or equal to the shortest valid arc length threshold, it is determined that the longest continuous complete arc segment cannot be found, and orbit determination is abandoned.

2. The method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite according to claim 1, characterized in that: S1, including: According to the name of the target low-orbit satellite to be detected, the orbit determination arc length, the arc segment start time point, and the detection sampling interval, each system in the GNSS system set to be detected is detected one by one within the observation arc segment determined by the arc segment start time point and the orbit determination arc length. For the detected system, if an epoch of the system containing dual-frequency observation of at least 4 satellites is found, it is determined that the system exists, so that after all systems are detected, the set of existing systems is obtained.

3. The method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite according to claim 2, characterized in that: In S1, the observation arc determined by the arc start time point and the orbit determination arc length has a start point that is the arc start time point and an end point that is the sum of the arc start time point and the orbit determination arc length.

4. The method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite according to claim 1, characterized in that: S2, including: According to the name of the target low-orbit satellite and the sampling interval of the detection, within the observation arc determined by the input arc start time point and the orbit determination arc length, find all epochs containing at least 4 satellites with dual-frequency observations of each system in the system set, and define the found epochs as valid epochs; The orbit determination arc segment from the first valid epoch to the last valid epoch is defined as a valid arc segment, its arc length is determined as the valid arc length, and the time of the first valid epoch is output as the start time of the valid arc segment; The number of valid epochs in the valid arc segment is divided by the expected number of epochs to obtain a percentage as the completeness; wherein the expected number of epochs is obtained according to the input orbit determination arc length and sampling interval; The longest arc length of the arc segment without a valid epoch that appears in the valid arc segment is determined as the longest discontinuity, and the first epoch in the longest discontinuity and the last epoch in the longest discontinuity are determined.

5. The method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite according to claim 1, characterized in that: S3, including: The three parameters of the current valid arc length, integrity and longest interruption are compared with the corresponding thresholds to determine whether the corresponding parameters meet the standards. When any of the parameters does not meet the standards, it is determined that the current valid arc segment does not meet the preset requirements for the integrity and continuity of the onboard GNSS observations. When all parameters meet the standards, it is determined that the current valid arc segment meets the preset requirements.

6. The method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite according to claim 1, characterized in that: In S5, the longer arc segment of the remaining first and last arc segments, excluding the arc segment corresponding to the longest discontinuity, is determined in the current valid arc segment, including: Calculate the arc length from the first epoch of the current valid arc to the epoch before the first epoch of the longest discontinuity as the first arc length; Calculate the arc length from the epoch after the last epoch of the longest discontinuity to the last epoch of the current valid arc as the second arc length; The longer one between the first arc segment length and the second arc segment length is selected, and the arc segment is defined as the longer arc segment.

7. The method for detecting the longest continuous complete arc segment of post-orbit determination timing of a low-orbit satellite according to claim 1, characterized in that: In S6, the orbit determination arc length and the arc start time point are updated by using the longer arc segment, including: The starting time point of the longer arc segment is used as the updated arc segment starting time point, and the arc length of the longer arc segment is used as the updated orbit determination arc length.

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