An automatic step-scan tracking method for a satellite communication antenna

Abstract

The application discloses an automatic step scanning tracking method for a satellite communication antenna and relates to the technical field of communication. The method combines a satellite communication antenna and satellite signal features, establishes a main surface scanning control mechanism, establishes a function relationship between a satellite signal strength and an angle error correction method and an automatic adjustment function relationship between the satellite signal strength and a scanning step, statistically analyzes satellite signal strength features, combines approximate directional diagram function characteristics of the antenna, obtains a minimum scanning step and a scanning suspension judgment method, and realizes automatic step scanning tracking of the satellite communication antenna. The application realizes better scanning tracking effect and tracking precision, reduces hardware wear and tear, prolongs system service life, and has the advantages of simple implementation and wide application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, in particular to an automatic step scanning tracking method for a satellite communication antenna. BACKGROUND

[0002] Satellite communication has a series of advantages such as large coverage, long communication distance, high quality, fast networking speed, and no restriction by geography and natural conditions, and plays an increasingly important role in modern information transmission. In order to ensure good communication effect, it is required that the satellite antenna is always accurately pointed to the satellite. The mainstream tracking methods of traditional dish antennas include single pulse tracking, step tracking and harmonic scanning tracking. Essentially, the three tracking methods are to compare the satellite signal strengths received by the antenna in the vicinity of the beam to determine the direction and size of the current pointing deviation, and accordingly drive the motor to rotate to adjust the beam to align the satellite. Considering the cost and accuracy, the harmonic scanning tracking method is the first choice for small and medium caliber antennas, which is mainly divided into a sub-surface rotating type and a main surface scanning type. The sub-surface rotating type scanning tracking method has a complex structure, and the scanning beam deviation angle is fixed, which has a fixed scanning loss. The main surface scanning type tracking method uses software to drive the beam deflection, does not require additional hardware support, and the scanning loss is controllable. Through the design of the scanning step, good pointing accuracy can be achieved. SUMMARY

[0003] Therefore, the present application provides an automatic step scanning tracking method for a satellite communication antenna, which is based on the main surface scanning tracking method, establishes the functional relationship between the satellite signal strength and the angular error correction method, and the automatic adjustment function relationship between the satellite signal strength and the scanning step, and realizes better scanning tracking effect.

[0004] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0005] An automatic step scanning tracking method for a satellite communication antenna, comprising the following steps:

[0006] Step 1, obtaining the satellite theoretical pointing angle, driving the antenna to search near the satellite theoretical pointing angle, and establishing the main surface scanning control mechanism in combination with the satellite signal characteristics and the satellite signal characteristics;

[0007] Step 2, establishing the functional relationship between the satellite signal strength and the angular error correction method, and the automatic adjustment function relationship between the satellite signal strength and the scanning step;

[0008] Step 3, combining the approximate directional diagram function characteristics of the antenna to obtain the minimum scanning step and the scanning termination judgment method, and realizing the automatic step scanning tracking of the satellite communication antenna.

[0009] Further, in step 1, the way of acquiring the satellite theoretical pointing angle has the following four kinds:

[0010] (1) According to the known address position coordinates of the satellite and the satellite communication antenna, the satellite theoretical pointing angle is calculated by using the angle formula between two points;

[0011]

[0012]

[0013] wherein A and E are the azimuth and elevation pointing angles of the satellite respectively, λ s、 H s are the longitude, latitude and height of the target satellite respectively, λ、 H are the longitude, latitude and height of the satellite antenna respectively;

[0014] (2) The satellite theoretical pointing angle is input in the form of a single fixed angle or an angle file;

[0015] (3) The satellite theoretical pointing angle is calculated by using a satellite orbit prediction algorithm;

[0016] (4) The satellite theoretical pointing angle is calculated by using a memory angle or a function fitting method.

[0017] Further, in step 1, the specific way of establishing the main surface scanning control mechanism is:

[0018] Step 101, the angular motion amount superimposed on the azimuth axis and the elevation axis is calculated:

[0019]

[0020]

[0021] wherein δ A and δ E are the scanning amplitudes of the azimuth axis and the elevation axis respectively, and are taken as 1 / 20-1 / 10 of the half-power beam width in the corresponding direction, k, N and m are integers not less than 0, k is the count in a single scanning period of the satellite communication antenna, N is the total number of control cycles in a single scanning period, N is an even number, and m is the scanning phase control amount, and m∈[0, N-1); the half-power beam width of the satellite communication antenna is determined by the following formula:

[0022]

[0023] wherein λ is the signal wavelength, and D is the equivalent aperture;

[0024] Step 102: Differentiate the angular motion quantities superimposed on the azimuth and pitch axes and use them as velocity feedforwards for the corresponding axes to complete the establishment of the master plane scanning control mechanism.

[0025] Furthermore, the specific method for step 2 is as follows:

[0026] Step 201, denoted as P, the normalized signal intensity within a single scan period. i , i = 1, 2, ..., N, calculate the azimuth deviation U A and pitch deviation U B :

[0027]

[0028]

[0029] Step 202: Based on the azimuth deviation and elevation deviation, adjust the azimuth axis to point towards center A and the elevation axis to point towards center E respectively, and establish the functional relationship between satellite signal strength and the angular error correction method:

[0030] A k+1 =A k -sign(U A )·dA

[0031] E k+1 =E k -sign(U E )·dE

[0032] Where dA and dE are constant correction values ​​greater than 0, taken as 1 / 40 to 1 / 20 of the half-power beamwidth in the corresponding direction, sign() is the sign function, subscripts k and k+1 indicate time, and A and E are the azimuth and elevation values ​​at the corresponding time.

[0033] Step 203: Establish an automatic adjustment function relationship between satellite signal strength and scanning step distance based on azimuth and elevation deviations.

[0034]

[0035]

[0036] Where, α A α E β A β E It is a constant greater than 0.

[0037] Furthermore, the specific method for step 3 is as follows:

[0038] Step 301: Acquire and record satellite signal strength P i, the mean value of the signal strength is calculated once every M satellite signal strength is collected and variance σ:

[0039]

[0040]

[0041] Step 302, continuously record the mean value of the signal strength of two groups or more and variance σ, and sequentially calculate the difference to obtain the mean value variation dP and variance variation dσ of adjacent calculation periods; when dP < ε and dσ < Δ are simultaneously satisfied, it is determined that the antenna tracking effect is good, and step 303 is executed, otherwise it is determined that the antenna tracking effect is not good, and the satellite signal strength is continuously scanned and step 2 is re-executed; wherein, ε and Δ are signal strength fluctuation thresholds of the antenna tracking;

[0042] Step 303, within the range of the main beam of the antenna, the pattern function is approximated as a parabola, σ is regarded as the signal strength loss within the main beam of the sky-wave antenna, and the angular deviation δ is obtained according to the characteristics of the parabola function When , δ A and δ E are set to zero, the scanning is stopped, dθ is the minimum comprehensive scanning step, and the current signal strength mean value P is recorded

[0043] Step 304, after the scanning is stopped, the mean value of the signal strength is calculated every M satellite signal strength is collected When , the satellite signal strength is re-scanned and step 2 is re-executed; P TH is a tracking error threshold of the sky-wave antenna;

[0044] Thus, the automatic step scanning tracking of the satellite communication antenna is realized.

[0045] The beneficial effects of the above technical solution are as follows:

[0046] 1. The present application is based on the main surface scanning tracking mode, and differential speed feedforward of the superimposed angle motion quantity is introduced on the speed loop to realize excellent scanning precision.

[0047] 2. The present application can realize tracking precision superior to the traditional mode through automatic adjustment of the scanning step and correction of the pointing angle.

[0048] 3. The present application obtains the minimum scanning step and the scanning termination judgment method according to the statistical characteristics of the satellite signal strength and the antenna characteristics in the tracking process, reduces the hardware wear, improves the system life, and has the advantages of simple implementation and wide application range. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is the main surface scanning control mechanism block diagram in the embodiment of the application;

[0050] Figure 2 is the signal strength change simulation curve in the scanning tracking process in the embodiment of the application;

[0051] Figure 3 is the azimuth, elevation axis scanning step distance change simulation curve in the scanning tracking process in the embodiment of the application. DETAILED DESCRIPTION

[0052] The technical solutions of the application will be further described in detail below in combination with the drawings and specific embodiments.

[0053] An automatic step scanning tracking method for a satellite communication antenna, comprising the following steps:

[0054] (1) acquiring a satellite theoretical pointing angle, driving the antenna to search in a small range near the theoretical pointing angle, and when the received satellite signal strength reaches a threshold TH, combining the satellite communication antenna and satellite signal characteristics to establish a main surface scanning control mechanism;

[0055] (2) establishing a functional relationship between the satellite signal strength and the angle error correction method, and an automatic adjustment function relationship between the satellite signal strength and the scanning step distance;

[0056] (3) statistically acquiring satellite signal strength characteristics, combining the approximate directional diagram function characteristics of the antenna to obtain a minimum scanning step distance and a scanning termination judgment method, and realizing the automatic step scanning tracking of the satellite communication antenna.

[0057] Further, the specific manner of the step (1) is:

[0058] (101) acquiring a satellite theoretical pointing angle, including but not limited to the following four ways:

[0059] (1011) knowing the address position coordinates of the satellite and the satellite communication antenna, and using a pointing angle calculation formula between two points;

[0060]

[0061]

[0062] wherein A and E are the azimuth and elevation pointing angles of the satellite, λ s、 H s are the longitude, latitude and height of the target satellite, λ、 H are the longitude, latitude and height of the satellite antenna;

[0063] (1012) input in a single fixed angle or angle file form;

[0064] (1013) calculate satellite pointing angle using satellite orbit prediction algorithm;

[0065] (1014) calculate satellite pointing angle using memory angle or function fitting method.

[0066] (102) drive the antenna to search in a small range around the theoretical pointing angle, combine the features of the satellite communication antenna and satellite signal, and establish a main surface scanning control mechanism as shown in FIG. 2. Figure 1 The specific method is as follows:

[0067] (1021) the azimuth axis superimposes an angle movement the elevation axis superimposes an angle movement wherein δ A and δ E are the scanning amplitudes of the azimuth axis and the elevation axis respectively, and are generally 1 / 20-1 / 10 of the half-power beam width in the corresponding direction. k, N, and m are integers not less than 0, k is the count in a single scanning period of the satellite communication antenna, N is the total number of control cycles in a single scanning period and is even, and m is the scanning phase control quantity, and m∈[0, N-1). The half-power beam width of the satellite communication antenna is determined by the following formula:

[0068]

[0069] wherein λ is the signal wavelength, and D is the equivalent aperture.

[0070] (1022) difference the angle movements added on the azimuth axis and the elevation axis, as the speed feedforward of the corresponding axis, to complete the establishment of the main surface scanning control mechanism.

[0071] Further, the specific method of the step (2) is as follows:

[0072] (201) let the normalized signal strength in a single scanning period be P i , i=1, 2,..., N. Let the azimuth and elevation deviation degrees be U

[0073]

[0074]

[0075] (202) adjust the azimuth axis pointing center A and the elevation axis pointing center E according to the azimuth and elevation deviation degrees respectively, to establish the function relationship between the satellite signal strength and the angle error correction method:

[0076] A k+1 = A k -sign(U A )·dA

[0077] E k+1 =E k -sign(U E )·dE

[0078] wherein dA, dE are constant correction values greater than 0, generally taking the half-power beam width of the corresponding direction 1 / 40~1 / 20;

[0079] (203) According to the azimuth, pitch deviation degree to establish satellite signal strength and scanning step distance automatic adjustment function relationship:

[0080]

[0081]

[0082] wherein α A , α E , β A , β E are constants greater than 0. The loss curve of signal strength relative to the maximum value in the scanning process is shown in Figure 2 , and the change curve of scanning step distance is shown in Figure 3 . It can be seen that in the part of the sampling point count value less than 3600, the signal strength gradually increases, and the scanning step distance is automatically adjusted. The fluctuation of scanning step distance is caused by satellite signal strength noise.

[0083] Further, the specific manner of the step (3) is:

[0084] (301) Collect and record satellite signal strength P i , every interval of a period of time t or a certain number M, calculate the signal strength mean value and variance σ once according to the following formula:

[0085]

[0086]

[0087] wherein t=M·T, T is the interval time of recording satellite signal strength P i ;

[0088] (302) Continuously record 2 groups of signal strength mean value variance and σ, and sequentially calculate the difference to obtain the mean value change dP and variance change dσ of adjacent calculation periods. When dP<ε and dσ<Δ are satisfied at the same time, it is determined that the antenna tracking effect is good, and step (303) is executed, otherwise it is determined that the antenna tracking effect is not good, and the scanning step is continued; wherein ε, Δ are signal strength fluctuation thresholds of antenna tracking; ​

[0089] (303) Within the main beam range of the antenna, its radiation pattern function can be approximated as a parabola. σ is considered as the signal strength loss within the main beam of the satellite communication antenna. Based on the characteristics of the parabolic function, the angular deviation can be obtained. when At that time, δ A δ E Set to zero and stop scanning; that is, dθ is the minimum integrated scan step size. For example... Figure 2 and Figure 3 As shown, when the number of sampling points exceeds 4000, the signal strength loss curve relative to the maximum value tends to stabilize, at which point δ A δ E Set to zero. Record the current average signal strength as zero.

[0090] (304) After stopping the scan, calculate the average signal strength at intervals t or after collecting a certain number of samples M. when At that time, restart the scanning process, P TH This is the tracking error threshold for satellite communication antennas.

[0091] This enables automatic step-range scanning and tracking of satellite communication antennas.

[0092] In summary, this invention establishes a main plane scanning control mechanism based on the characteristics of satellite communication antennas and satellite signals; it establishes an automatic adjustment function relationship between satellite signal strength and scanning step distance, and an angular error correction method; based on the statistical characteristics of satellite signal strength and antenna characteristics during tracking, it obtains the minimum scanning step distance and a scanning termination judgment method, achieving better scanning tracking effect and tracking accuracy, while reducing hardware wear and improving system lifespan and reliability. In conclusion, this invention achieves high-precision tracking of satellite communication antennas without increasing additional hardware costs, through software algorithms, and has the advantages of simple implementation and wide applicability.

Claims

1. An automatic step-scan tracking method for satellite communication antennas, characterized in that, Includes the following steps: Step 1: Obtain the theoretical pointing angle of the satellite, drive the antenna to search near the theoretical pointing angle, and establish a main plane scanning control mechanism by combining the characteristics of the satellite communication antenna and the satellite signal. The specific method for establishing the main plane scanning control mechanism is as follows: Step 101, calculate the superimposed angular motion on the azimuth and pitch axes: in, , These represent the scanning amplitudes for the azimuth and elevation axes, respectively, taken as 1 / 20 to 1 / 10 of the half-power beamwidth in the corresponding directions. k, N, and m are integers not less than 0. k is the count within a single scanning cycle of the satellite communication antenna, N is the total number of control cycles within a single scanning cycle (N is an even number), and m is the scanning phase control value. The half-power beamwidth of a satellite communication antenna is determined by the following formula: in Where λ is the signal wavelength and D is the equivalent aperture; Step 102: Differentiate the angular motion quantities superimposed on the azimuth and pitch axes and use them as velocity feedforwards for the corresponding axes to complete the establishment of the master plane scan control mechanism. Step 2: Establish the functional relationship between satellite signal strength and the angular error correction method, as well as the automatic adjustment functional relationship between satellite signal strength and scanning step distance; specifically, the method is as follows: Step 201, record the normalized signal intensity within a single scan period as: , Calculate the azimuth deviation U A and pitch deviation U B : Step 202: Based on the azimuth deviation and elevation deviation, adjust the azimuth axis to point towards center A and the elevation axis to point towards center E respectively, and establish the functional relationship between satellite signal strength and the angular error correction method: Where dA and dE are constant correction values ​​greater than 0, taken as 1 / 40 to 1 / 20 of the half-power beamwidth in the corresponding direction, sign() is the sign function, subscripts k and k+1 indicate time, and A and E are the azimuth and elevation values ​​at the corresponding time. Step 203: Establish an automatic adjustment function relationship between satellite signal strength and scanning step distance based on azimuth and elevation deviations: in, , , , It is a constant greater than 0; Step 3: Analyze the satellite signal strength characteristics and, combined with the approximate radiation pattern function characteristics of the antenna, obtain the minimum scanning step distance and a method for determining scanning termination, thus achieving automatic step distance scanning and tracking of the satellite communication antenna; the specific method is as follows: Step 301: Collect and record satellite signal strength. Each collection After analyzing the signal strength of each satellite, calculate the average signal strength using the following formula. and variance : Step 302: Record the average signal strength of at least two sets consecutively. and variance The difference is calculated successively to obtain the mean change in adjacent calculation periods. and variance change When both conditions are met and If the antenna tracking effect is deemed good, step 303 is executed; otherwise, if the antenna tracking effect is deemed poor, the satellite signal strength is scanned again and step 2 is executed again. , The threshold for signal strength fluctuations during antenna tracking; Step 303: Within the main beam range of the antenna, approximate the radiation pattern function as a parabola, and consider... The angular deviation is obtained based on the characteristics of the parabolic function to determine the signal strength loss within the main beam of the satellite communication antenna. ,when At that time, , Set to zero, stop scanning, that is To determine the minimum integrated scan step size, the average current signal strength is recorded as follows: ; Step 304, after stopping the scan, for each acquisition After analyzing the signal strength of each satellite, calculate the average signal strength. ,when If necessary, rescan the satellite signal strength and repeat step 2; This is the tracking error threshold for satellite communication antennas.

2. The automatic step-scanning tracking method for satellite communication antennas according to claim 1, characterized in that, In step 1, there are four ways to obtain the theoretical pointing angle of the satellite: (1) Based on the known address coordinates of the satellite and the satellite communication antenna, calculate the theoretical pointing angle of the satellite using the angle formula between the two points; In the formula, A and E are the satellite azimuth and elevation pointing angle, respectively. , These are the longitude, latitude, and altitude of the target satellite, respectively. , , These are the longitude, latitude, and altitude of the satellite antenna, respectively. (2) Input the satellite's theoretical pointing angle in the form of a single fixed angle or an angle file; (3) Use satellite orbit prediction algorithms to calculate the theoretical pointing angle of the satellite; (4) Use memory angle or function fitting method to calculate the theoretical pointing angle of the satellite.

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