Synchronous orbit satellite rapid maneuvering detection method based on time difference

Abstract

The invention discloses a synchronous orbit satellite rapid maneuvering detection method based on time difference, and aims to solve the problem of maneuvering detection of synchronous orbit satellites under a radio monitoring system. According to the property that the difference residual between a time difference measurement value of a satellite signal arriving at two receiving stations and a theoretical value of forecast ephemeris calculation can be approximate to a linear function of a satellite position error, the difference residual between two different moments is used as a test statistic to detect whether a satellite is maneuvered or not. According to the method, the number of the parameters to be estimated and the requirement for the observation arc length are greatly reduced, rapid maneuvering detection of the synchronous orbit satellite can be achieved only through several minutes of short arc section observation of the two receiving stations, and the timeliness of the system is improved while the complexity of the system is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace measurement and control, and in particular relates to a method for rapid maneuvering detection of a synchronous orbit satellite based on time difference. Background Art

[0002] Geosynchronous orbit satellites are an important part of the space assets of various countries. It is of great value and significance to quickly and accurately realize the maneuver detection of non-cooperative geosynchronous orbit satellites and grasp their motion status. During the orbital maneuvers of non-cooperative satellites, the maneuvering time and the magnitude of the maneuvering force are generally not known in real time and accurately. It will become very difficult to use the dynamic orbit determination method to detect the satellite maneuver. In addition, the dynamic orbit determination method often requires a long observation arc, and its timeliness is difficult to meet the growing application needs. Therefore, it is urgent to explore new methods for maneuvering detection of geosynchronous orbit satellites.

[0003] At present, there are three main means of observing synchronous orbit satellites: optical monitoring, radar detection, and radio monitoring. Optical monitoring cannot be observed during the day due to the influence of sky light, so it can only be observed at night. In addition, the observation time will be affected by factors such as cloudy days, fog, and atmospheric glow. The effective observation time is short, and it is impossible to achieve all-weather and full-arc observation of the target satellite. Radar detection has a very strong detection capability for medium and low orbit targets, but it needs to actively transmit detection signals, the observation point is easily exposed, and the effective range is limited. It is not suitable for the observation and orbit determination of high-orbit and deep-space targets. Radio monitoring realizes the positioning and orbit determination of synchronous orbit satellites by measuring the angle, distance, and time difference of the downlink signals forwarded by the satellite. It has the advantages of high concealment and all-weather monitoring. Compared with the other two methods, it is suitable for the monitoring and discovery of synchronous orbit satellites. Summary of the invention

[0004] The purpose of the present invention is to provide a method for rapid maneuvering detection of synchronous orbit satellites based on time difference, which solves the problem of low timeliness of existing non-cooperative maneuvering detection of synchronous orbit satellites.

[0005] The technical solution adopted by the present invention is: a method for rapid maneuvering detection of synchronous orbit satellites based on time difference, comprising the following steps:

[0006] Step 1: Correlate the downlink signals of the synchronous orbit satellite received by the two receiving stations to obtain the time difference observation value r from the satellite to the two receiving stations at time t. t ;

[0007] Step 2: Determine the initial orbit of the target satellite, and then use the initial orbit to predict the satellite ephemeris to the observation time t. Let the predicted ephemeris at the observation time t be s t ;

[0008] Step 3: Based on the predicted ephemeris s tThe theoretical time difference r of the observation time is calculated from the positions of the two receiving stations t c ;

[0009] Step 4: Calculate the time difference observation value r t Theoretical value of time difference r t c The difference Vr t And in the forecast ephemeris t At first-order Taylor expansion;

[0010] Step 5: The time difference observation value r between two different times t1 and t2 t Theoretical value of time difference r t c The difference is further differentiated, and the difference residual is used as the test statistic

[0011] Step 6: Use the 3σ criterion to determine the detection threshold. When the test statistic Δ exceeds the detection threshold, that is, It is determined that the satellite is maneuvering.

[0012] The present invention is also characterized in that:

[0013] The time difference observation value r in step 1 t The calculation formula is:

[0014] r t =r t o +n t

[0015] Where n t is the time difference random observation noise; r t o is the real time difference from the satellite to the two receiving stations at time t, expressed as:

[0016]

[0017] Where c1 and c2 are the coordinates of the two receiving stations in the geocentric system. is the satellite's position coordinates.

[0018] In step 2, historical observation data is used to determine the initial orbit of the target satellite.

[0019] In step 2, the TLE elements are downloaded from the Internet to determine the initial orbit of the target satellite.

[0020] The theoretical value of the time difference in step 3 is r t c The calculation formula is:

[0021] r t c=||c2-s t ||-||c1-s t ||

[0022] Where c1 and c2 are the coordinates of the two receiving stations in the geocentric system.

[0023] Step 4: VR t The calculation formula is:

[0024]

[0025] In the formula, (·) T Represents the matrix transpose operation, Vs t is the ephemeris error, n t is the time-difference random observation noise.

[0026] The calculation formula for the test statistic Δ in step 5 is:

[0027]

[0028] In step 6, it is assumed that the observation noise at time t1 and t2 is and All have zero mean and variance Gaussian noise, then has a mean of zero and a variance of Gaussian noise.

[0029] The beneficial effects of the present invention are as follows: the method for detecting rapid maneuvers of synchronous orbit satellites based on time difference of the present invention is different from the traditional dynamic method of first determining the orbit of the satellite and then determining whether the satellite maneuvers. Instead, it determines whether the satellite maneuvers by observing the influence of the satellite maneuver on the time difference, which greatly reduces the number of parameters to be estimated and the demand for the observation arc length. Only two receiving stations need to observe a short arc segment of several minutes to realize rapid maneuver detection of synchronous orbit satellites, which reduces the complexity of the system while also improving the timeliness of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic flow chart of a method for rapid maneuvering detection of a synchronous orbit satellite based on time difference of the present invention;

[0031] Figure 2 It is a schematic diagram of the change of the test statistic over time in the synchronous orbit satellite rapid maneuvering detection method based on time difference of the present invention. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Example 1

[0034] The present invention provides a method for rapid maneuvering detection of synchronous orbit satellites based on time difference. Aiming at the problem of maneuvering detection of synchronous orbit satellites under a radio monitoring system, the present invention utilizes the property that the differential residual of the time difference measurement value of the satellite signal arriving at two receiving stations and the theoretical value calculated by the predicted ephemeris can be approximated as a linear function of the satellite position error. The differential residual at two different times is used as a test statistic to detect whether the satellite maneuvers. Rapid maneuvering detection of synchronous orbit satellites can be achieved by only requiring two receiving stations to perform short arc observations.

[0035] Through the above implementation steps, rapid maneuver detection of synchronous orbit satellites based on dual-station time difference observation data can be achieved. The observation data required for maneuver detection usually only takes a few minutes, which reduces the complexity of the system and improves the timeliness of the system.

[0036] Example 2

[0037] The present invention provides a method for rapid maneuvering detection of synchronous orbit satellites based on time difference, such as Figure 1 As shown, the following steps are included:

[0038] 1) Perform correlation processing on the downlink signals of the synchronous orbit satellite received by the two receiving stations to calculate the time difference r from the satellite to the two receiving stations at time t t , considering the existence of random observation errors, let r t =r t o +n t , r t o is the real time difference between the satellite and the two receiving stations at time t, n t is the time difference random observation noise, according to the geometric relationship, c1 and c2 are the coordinates of the two receiving stations in the geocentric system, is the satellite's position coordinates.

[0039] 2) Use historical observation data to determine the initial orbit of the target satellite, and then use the initial orbit of the satellite to predict the satellite ephemeris to the observation time. The predicted ephemeris at time t is s t .

[0040] 3) Calculate the theoretical time difference r at the observation time based on the predicted ephemeris and the receiving station position t c =||c2-s t ||-||c1-s t ||.

[0041] 4) Calculate the difference between the observed time difference and the theoretical value and expand it into a first-order Taylor expansion at the predicted ephemeris Considering that the speed of synchronous satellites relative to the earth is relatively slow, Approximately unchanged, the differential residual can be approximately considered to be the ephemeris error Vs t A linear function of .

[0042] 5) Using the property that the difference between the observed and theoretical time difference of the two receiving stations is a linear function of the ephemeris error, the difference between the observed and theoretical time difference at two different times t1 and t2 is calculated as and Further difference, and the difference residual is used as the test statistic When the satellite does not maneuver during the period from t1 to t2, the ephemeris error of the predicted ephemeris can also be considered to be approximately constant in a short period of time, that is, So there is If there is a maneuver between t1 and t2, then So there is Therefore, Δ can be used as a test statistic to determine whether the satellite is maneuvering.

[0043] 6) Calculate the variance of random error of time difference measurement Assuming observation noise and All have zero mean and variance Gaussian noise, then has a mean of zero and a variance of The 3σ criterion is used to determine the detection threshold. When the test statistic exceeds the detection threshold, that is, It is determined that the satellite is maneuvering.

[0044] Example 3

[0045] The present invention provides a method for rapid maneuvering detection of synchronous orbit satellites based on time difference. In Example 2, when the initial orbit of the target satellite is determined without historical observation data, the TLE root number can be downloaded from the Internet instead.

[0046] Example 4

[0047] The data used is the fifth major orbit change process of a synchronous orbit satellite. The position coordinates of the two receiving stations in the ground-fixed coordinate system are s1 and s2 respectively, and the time difference random observation noise σ r =1m, differential time interval t2-t1=5min, the satellite starts maneuvering at the actual ignition time 877.8s. For the convenience of explanation, the ephemeris and time differences of four typical moments in the observation data as shown in Table 1 are taken to illustrate the implementation steps of the present invention.

[0048] Table 1 Ephemeris and time difference of observation data at typical times

[0049]

[0050] 1) Perform correlation processing on the downlink signals of the synchronous orbit satellite received by the two receiving stations to calculate the time difference r from the satellite to the two receiving stations at time t t .

[0051] 2) Use historical observation data to determine the initial orbit of the target satellite, and then use the initial orbit of the satellite to predict the satellite ephemeris to the observation time. Let the predicted ephemeris at time t be s t .

[0052] 3) Calculate the theoretical time difference r of the observation time using the predicted ephemeris and the receiving station position t c =||c2-s t ||-||c1-s t ||, the theoretical time differences of the 1st, 301st, 801st and 1101st seconds are 3313017.1ns, 3312445.9ns, 3311535.9ns and 3311015.0ns respectively.

[0053] 4) Calculate the difference between the observed time difference and the theoretical value Vr t The differences between the observed and theoretical time differences at the 1st, 301st, 801st and 1101st seconds are: -166.3ns, -173.5ns, -180.5ns, -161.7ns respectively.

[0054] 5) If Figure 2 As shown, construct the test statistic Determine the differential time interval as t2-t1=5min. If t1=1s, t2=301s, then the test statistic Δ=7.2ns.

[0055] 6) Using the 3σ criterion to determine the detection threshold is Obviously, if t1=1s, t2=301s, Δ=7.2ns<14.1ns, it is determined that the satellite has not maneuvered.

[0056] Example 5

[0057] In Example 4, if t1 = 801 s, t2 = 1101 s, the test statistic Δ is 18.5 ns, which is greater than the detection threshold of 14.1 ns, and it can be determined that the satellite has maneuvered.

[0058] Example 6

[0059] In Example 4, when determining the initial orbit of the target satellite, if there is no historical observation data, the TLE roots can be downloaded from the Internet instead.

Claims

1. A method for rapid maneuvering detection of synchronous orbit satellites based on time difference, characterized in that: The following steps are involved: Step 1: Correlate the downlink signals of the synchronous orbit satellite received by the two receiving stations to obtain the time difference observation value r from the satellite to the two receiving stations at time t. t ; Step 2: Determine the initial orbit of the target satellite, and then use the initial orbit to predict the satellite ephemeris to the observation time t. Let the predicted ephemeris at the observation time t be s t ; Step 3: Based on the predicted ephemeris s t The theoretical time difference r of the observation time is calculated from the positions of the two receiving stations t c ; Step 4: Calculate the time difference observation value r t Theoretical value of time difference r t c The difference Vr t And in the forecast ephemeris t At first-order Taylor expansion; Step 5: The time difference observation value r between two different times t1 and t2 t Theoretical value of time difference r t c The difference is further differentiated, and the difference residual is used as the test statistic Step 6: Use the 3σ criterion to determine the detection threshold. When the test statistic Δ exceeds the detection threshold, that is, It is determined that the satellite is maneuvering.

2. The method for rapid maneuvering detection of synchronous orbit satellites based on time difference as claimed in claim 1, characterized in that: The time difference observation value r in step 1 t The calculation formula is: r t ＝r t o +n t Where n t is the time difference random observation noise; r t o is the real time difference from the satellite to the two receiving stations at time t, expressed as: Where c1 and c2 are the coordinates of the two receiving stations in the geocentric system. is the satellite's position coordinates.

3. The method for rapid maneuvering detection of synchronous orbit satellites based on time difference as claimed in claim 1, characterized in that: In step 2, the historical observation data is used to determine the initial orbit of the target satellite.

4. The method for rapid maneuvering detection of synchronous orbit satellites based on time difference as claimed in claim 1, characterized in that: In step 2, the TLE elements are downloaded from the Internet to determine the initial orbit of the target satellite.

5. The method for rapid maneuvering detection of synchronous orbit satellites based on time difference as claimed in claim 1, characterized in that: The theoretical time difference value r in step 3 t c The calculation formula is: r t c =||c2-s t ||-||c1-s t || Where c1 and c2 are the coordinates of the two receiving stations in the geocentric system.

6. The method for rapid maneuvering detection of synchronous orbit satellites based on time difference as claimed in claim 5, characterized in that: In step 4, Vr t The calculation formula is: In the formula, (·) T Represents the matrix transpose operation, Vs t is the ephemeris error, n t is the time-difference random observation noise.

7. The method for rapid maneuvering detection of synchronous orbit satellites based on time difference as claimed in claim 6, characterized in that: The calculation formula of the test statistic Δ in step 5 is:

8. The method for rapid maneuvering detection of synchronous orbit satellites based on time difference as claimed in claim 7, characterized in that: In step 6, it is assumed that the observation noise at time t1 and t2 and All have zero mean and variance Gaussian noise, then has a mean of zero and a variance of Gaussian noise.

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