Method for tracking inclined orbit synchronous satellite through communication-in-moving antenna

Abstract

The invention discloses a method for tracking an inclined orbit synchronous satellite through a communication-in-moving antenna, and relates to the technical field of communication. The method comprises the following steps: firstly, acquiring the spatial position of an IGSO satellite for several consecutive days, performing off-line curve fitting on the satellite position by using a trigonometric function polynomial, and determining polynomial parameters; then, the antenna uses the fitting polynomial to calculate the satellite space position for searching and tracking, and stores the reversely calculated satellite space position at the same time; and finally, judging that the fitting parameters are not suitable any more by comparing fitting and reverse calculation results, and re-determining the fitting parameters by using the stored satellite spatial position when the parameters are not suitable. According to the method, a complex online orbit prediction algorithm is avoided, accurate tracking of the communication-in-moving antenna on the IGSO satellite is achieved, and the method is suitable for a fixed station, a portable station and the communication-in-moving antenna.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and particularly to a method for a mobile satellite communication (MSC) antenna to track an inclined orbit geosynchronous satellite. Background Art

[0002] Inclined geosynchronous orbit (IGSO) satellites combine the advantages of geostationary orbit and medium earth orbit satellites, providing a wider coverage area than traditional geostationary orbit satellites. This unique orbital structure enables IGSO satellites to cover high-latitude regions, solving the problem of insufficient signal coverage of conventional geodetic observation satellites in these regions. In addition, the orbital period of IGSO satellites is consistent with the earth's rotation period, ensuring that their positions relative to the earth's surface remain relatively unchanged, thus providing stable communication services for ground users.

[0003] The spatial pointing angle of satellites is crucial for antennas to accurately track them, especially for MSC antenna systems. The direction of the antenna must be continuously adjusted to ensure a stable signal connection between the antenna and the satellite as the satellite moves in the sky, which requires accurately obtaining the spatial position of the satellite. Satellite orbit prediction based on Two-Line Element (TLE) data is the most widely used method. However, due to the timeliness of TLE data, the antenna needs to frequently update the TLE data to ensure accurate calculation of the satellite position. Summary of the Invention

[0004] In view of this, the present invention proposes a method for an MSC antenna to track an inclined orbit geosynchronous satellite. This method realizes the fitting of the satellite spatial position based on orbit prediction offline data, avoids complex online orbit prediction algorithms, and realizes accurate tracking of IGSO satellites by the MSC antenna.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for an MSC antenna to track an inclined orbit geosynchronous satellite, comprising the following steps:

[0007] Step 1, obtaining the spatial positions of an IGSO satellite for a continuously set number of days;

[0008] Step 2, performing offline curve fitting on the satellite spatial positions using trigonometric polynomials to determine the fitting polynomial parameters;

[0009] Step 3, the antenna calculates the satellite spatial position using the fitting polynomial and performs search and tracking, and simultaneously stores the satellite spatial position calculated in reverse;

[0010] Step 4, comparing the calculation results of the fitting polynomial and the results calculated in reverse. If the difference does not exceed the threshold, execute Step 3; otherwise, determine that the fitting parameters are no longer applicable and execute Step 1.

[0011] Further, the method for obtaining the spatial position of the satellite in step 1 is as follows: collecting the actual position data of the IGSO satellite or using an orbit prediction algorithm for offline prediction; the orbit prediction algorithm includes an orbit prediction algorithm based on two-line elements, IntelSat-11 parameters, and instantaneous roots.

[0012] Further, the form of the trigonometric polynomial in step 2 is as follows:

[0013]

[0014] where ω = 0.0043754 rad / min, the unit of time t is min, n is an integer not less than 2, k is the order, A k , p k and B are fitting parameters.

[0015] Further, the specific process of step 3 is as follows:

[0016] Step 301, collect the UTC time and the position data of the antenna. The position data includes longitude λ, latitude and altitude H;

[0017] Step 302, calculate the spatial position of the satellite at the current moment using the fitting polynomial, including longitude λ s , latitude and altitude H s ;

[0018] Step 303, determine whether the antenna is accurately pointed at the satellite according to the received signal strength indication (RSSI) of the satellite; if the RSSI is greater than the reception threshold TH, then execute step 304, otherwise, perform a uniaxial coarse search in azimuth and a biaxial fine search in azimuth and elevation in sequence, and then repeat this step until the RSSI is greater than the reception threshold TH;

[0019] Step 304, solve the following formula, and inversely calculate the actual position of the satellite, including longitude λ s ', latitude s ' and altitude ' based on the azimuth angle A, elevation angle E, and satellite altitude H when the antenna is aligned with the satellite, and store them:

[0020]

[0021] where R = 6378140 in the formula.

[0022] Further, the specific process of step 4 is as follows:

[0023] Step 401, calculate the difference between the calculation result of the fitting polynomial and the inverse calculation result according to the following formula, including the longitude difference Δλ and the latitude difference

[0024] Δλ = λs '-λ s

[0025]

[0026] Step 402, if Δλ < λ TH and then execute Step 304; otherwise, determine that the fitting parameters are no longer applicable and execute Step 1; where λ TH and are the thresholds of the longitude difference and the latitude difference respectively.

[0027] The beneficial effects of the present invention adopting the above technical solutions are as follows:

[0028] 1. The present invention fits the position of the satellite in space by using a trigonometric polynomial, thus avoiding the problem of having to execute complex orbit prediction algorithms during actual operation and simplifying the calculation process.

[0029] 2. The object of fitting in the present invention is the position of the satellite in the earth coordinate system, which is applicable not only to fixed station and portable station antennas, but also to antennas for communication while moving, and has good applicability. Description of the Drawings

[0030] Figure 1 is a flowchart of a method for an antenna for communication while moving to track an inclined orbit geostationary satellite in an embodiment of the present invention.

[0031] Figure 2 are the antenna pointing angle, the actual pointing angle of the antenna tracking the satellite and their error curves calculated by using the fitted satellite position in an embodiment of the present invention.

[0032] Figure 3 is the total angle error curve of the antenna pointing angle calculated by using the fitted satellite position in an embodiment of the present invention. Detailed Embodiments

[0033] The following further describes the content of the present invention in conjunction with the drawings and specific embodiments.

[0034] A method for an antenna for communication while moving to track an inclined orbit geostationary satellite, the flowchart is as Figure 1 shown, and includes the following steps;

[0035] Step 1, obtain the spatial positions of an IGSO satellite for several consecutive days;

[0036] It is possible to collect the actual satellite position data or use an orbit prediction algorithm for offline prediction. The orbit prediction algorithm includes, but is not limited to, the orbit prediction algorithms based on Two-Line Elements (TLE), IntelSat-11 parameters, and instantaneous roots. The prediction time is generally set to 2 - 10 days; in this example, the orbit prediction algorithm based on Two-Line Elements (TLE) is adopted, and the prediction time is set to 7 days; the satellite position is the longitude λ s , latitude and altitude H s .

[0037] Step 2: Use a trigonometric polynomial to perform offline curve fitting on the satellite's spatial position and determine the fitting polynomial parameters; the form of the trigonometric polynomial is:

[0038]

[0039] where ω = 0.0043754 (rad / min), the unit of time t is min, n is an integer not less than 2, k is the order, and A k , p k and B are the fitting parameters.

[0040] In this example, n = 3 when fitting the longitude and latitude, and n = 2 when fitting the altitude. The pointing angles calculated using the fitted satellite position are compared with the actual angles during satellite tracking as shown in Figure 2 and Figure 3 .

[0041] Step 3: The antenna uses the fitting polynomial to calculate the satellite's spatial position and performs search and tracking, while storing the satellite's spatial position calculated in reverse.

[0042] Further, the specific process of Step 3 is as follows:

[0043] Step 301: Collect the UTC time and the position data of the antenna (longitude λ, latitude and altitude H);

[0044] Step 302: Use the fitting polynomial to calculate the satellite's spatial position at the current moment (longitude λ s , latitude and altitude H s );

[0045] Step 303: Determine whether the antenna is accurately pointing at the satellite based on the Received Signal Strength Indicator (RSSI) of the satellite; if the RSSI is greater than the reception threshold TH, then perform Step 304 for satellite tracking, otherwise, perform uniaxial coarse search in azimuth and biaxial fine search in azimuth and elevation in sequence, and then repeat this step until the RSSI is greater than the reception threshold TH;

[0046] Step 304, solve the following formula, according to the azimuth angle A, elevation angle E when the antenna is aligned with the satellite, and the satellite height H s Inverse calculate the actual position of the satellite (longitude λ s ' and latitude ) and store it:

[0047]

[0048] In the formula, R = 6378140 (m).

[0049] Step 4, satellite spatial consistency judgment, the specific process is as follows:

[0050] Step 401, calculate the difference between the fitting and inverse calculation results according to the following formula, including the longitude difference Δλ and the latitude difference

[0051] Δλ = λ s '- λ s

[0052]

[0053] Step 402, if Δλ < λ TH and then execute Step 3; otherwise, determine that the fitting parameters are no longer applicable and execute Step 1. Among them, λ TH and are the thresholds of the longitude difference and the latitude difference respectively, both of which are 0.1° in this example.

[0054] Those skilled in the art will realize that the described embodiments are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to the described embodiments. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A method for tracking an inclined orbit synchronous satellite using a moving antenna, characterized in that: The steps include: Step 1, obtaining the spatial position of the IGSO satellite for a set number of consecutive days; Step 2, using trigonometric polynomials to perform offline curve fitting on the satellite spatial position and determine fitting polynomial parameters; Step 3, the antenna calculates the satellite space position using the fitting polynomial and searches and tracks, and stores the reverse calculated satellite space position; Step 4, compare the calculation result of the fitting polynomial and the reverse calculation result. If the difference does not exceed the threshold, execute step 3; otherwise, determine that the fitting parameters are no longer applicable, and execute step 1.

2. The method for tracking an inclined orbit synchronous satellite using a moving antenna according to claim 1, characterized in that: The spatial position of the satellite in step 1 is obtained by collecting the actual position data of the IGSO satellite or using an orbit prediction algorithm for offline prediction; the orbit prediction algorithm includes an orbit prediction algorithm based on two-row roots, IntelSat-11 parameters and instantaneous roots.

3. The method for tracking an inclined orbit synchronous satellite using a moving antenna according to claim 1, characterized in that: The trigonometric polynomial in step 2 is of the form: Where ω = 0.0043754 rad / min, the unit of time t is min, n is an integer not less than 2, k is the order, A k 、p k and B are fitting parameters.

4. The method for tracking an inclined orbit synchronous satellite using a moving antenna according to claim 2, characterized in that: The specific process of step 3 is: Step 301, collect UTC time and antenna location data, the location data includes longitude λ, latitude and height H; Step 302, using the fitting polynomial to calculate the satellite spatial position at the current time, including the longitude λ s ,latitude and height H s ; Step 303, judging whether the antenna is accurately pointing to the satellite according to the satellite received signal strength RSSI; if the RSSI is greater than the receiving threshold TH, executing step 304, otherwise executing the azimuth single-axis coarse search and the azimuth and elevation dual-axis fine search in sequence, and then repeating this step until the RSSI is greater than the receiving threshold TH; Step 304, solve the following equation, based on the azimuth angle A, the pitch angle E and the satellite height H when the antenna is aimed at the satellite s Reverse calculate the actual position of the satellite, including longitude λ s ' and latitude And store: In the formula, R=6378140.

5. The method for tracking an inclined orbit synchronous satellite using a moving antenna according to claim 4, characterized in that: The specific process of step 4 is: Step 401, calculate the difference between the fitting polynomial calculation result and the reverse calculation result according to the following formula, including the longitude difference Δλ and the latitude difference Step 402, if Δλ<λ TH and Then execute step 304; otherwise, it is determined that the fitting parameters are no longer applicable, and execute step 1; wherein, λ TH and are the thresholds for longitude difference and latitude difference, respectively.

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