JPH1020010A - Satellite tracking system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To converge an error in a prediction tracking of a satellite so as to improve tracking precision by converging an error of the coefficient of a satellite orbital function and optimizing the coefficient. SOLUTION: Using satellite locus information accumulated in a satellite locus information storage unit 11, a recurrent analysis unit 12 finds an orbital function for a satellite according to a linear recurrent analysis. Coefficients of the satellite orbital function found in this process are stored in a recurrent coefficient storage unit 13 sequently. A recurrent coefficient evaluation unit 14 averages the stored regression coefficients so as to evaluate them optimally. A satellite position/command angle computing unit 15 finds a predicted satellite position and a command angle (an azimuth or an elevation angle) to be given to an antenna unit 17 on the basis of the optimally evaluated recurrent coefficient. An antenna control unit 16 controls and drives the antenna unit 17 so that an antenna is directed at the command angle found in the satellite position/ command angle computing unit 15. The antenna control unit 16 drives the antenna unit 17 according to a step track system in every fixed time and acquires a satellite so as to store it as new satellite locus information in the satellite locus information storage unit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite tracking system, and more particularly to a satellite tracking system for predicting a current satellite position using past satellite trajectory information in an automatic satellite tracking system.

[0002]

2. Description of the Related Art In a conventional satellite tracking system for a geostationary satellite, an antenna is moved stepwise little by little while monitoring the reception level of a radio wave transmitted from the geostationary satellite, and a position where the reception level becomes the highest is determined. The search step track method was the mainstream.

However, since the step track method is a method using a received wave, satellite tracking is interrupted when a decrease in the reception level or a large fluctuation occurs in the reception level. During the suspension of the satellite tracking, there has been a problem that the automatic tracking becomes impossible if the geostationary satellite moves largely and the reception level does not return.

Therefore, a memory tracking method or an IESS-412 program tracking method has been used for backup.

[0005] The memory tracking method utilizes the fact that the motion of a geostationary satellite is in a one-day cycle, and adds the angle information two cycles before to the angle information one cycle before or the angle information one cycle before and adds the angle information two cycles before to this. It calculates the position. However, in the case of a scintillation phenomenon in which the reception level fluctuates at the same time every day, the angle information before one cycle or two cycles before cannot be captured. Therefore, in this case, there is a problem that the memory tracking method cannot cope. .

[0006] The ESS-412 program tracking method is as follows.
The position of the geostationary satellite is calculated using 11 orbit elements of the geostationary satellite without using the received wave. However, this method has a problem that it is necessary to regularly obtain 11 orbital elements from the satellite operation center.

In order to solve such a problem, the applicant of the present invention has proposed a satellite tracking method for predicting the current position of a geosynchronous satellite by performing a linear regression analysis by a least squares method in Japanese Patent Application No. 5-68986. ing. Hereinafter, the outline of the satellite tracking method will be described.

FIG. 4 is a functional block diagram of the satellite tracking system. FIG. 5 is a flowchart of the satellite tracking method.

First, it is determined whether or not past satellite trajectory information is stored in the satellite trajectory information storage unit 21 for at least one cycle (S21). If the satellite trajectory information is not stored for one cycle, the antenna control unit 26 drives the antenna unit 27 by the step track method to acquire the position of the satellite (S27), and uses the position as the satellite trajectory information. The information is stored in the information storage unit 21 (M21). On the other hand, when the satellite trajectory information is stored for one cycle or more, the satellite trajectory information storage unit 21 stores the information for a certain period (for example,
The satellite trajectory information (for one cycle) is read (S22). Then, the regression analysis processing unit 22 obtains the orbit function of the satellite using the linear regression analysis by the least square method (S23).

Next, it is determined whether it is time to store new satellite track information (for example, every hour) (S24). If the memory time has not been reached, the satellite position
The command angle calculation processing unit 25 calculates the current satellite position using the orbit function obtained in step S23,
Command angle (azimuth angle and elevation angle) given to S7 (S
25). The command angle obtained here is input to the antenna control unit 26, and the antenna unit 27 is driven according to an instruction from the antenna control unit 26 (S26).

If it is determined in step S24 that the storage time of the new satellite trajectory information has come, the antenna control unit 26 uses the step track method to set the antenna unit 2
7, the position of the satellite is acquired (S27), and the position is used as new satellite trajectory information.
1 and stored (M21).

The above operations are repeated, and the latest satellite trajectory information is always used to perform satellite tracking and prediction.

The orbit function used for predicting and tracking the satellite described above is a function obtained by approximating the movement of the satellite viewed from the ground station by a polynomial. However, in practice, a geosynchronous satellite cannot orbit accurately in a geosynchronous orbit. Therefore, the accumulated satellite trajectory information necessarily includes this error. In addition, the apparent trajectory of the satellite varies depending on the position of the ground station. For this reason, in the ground station at a specific position, the coefficient should be originally 0 in the satellite orbit function, but an unnecessary term having a certain value is actually included due to the above-mentioned error. I have. If the orbit function including the unnecessary term is applied to the subsequent tracking of the satellite, there is a problem that the influence of an error occurs to a considerable extent and the accuracy of the predicted tracking is deteriorated.

In connection with the present invention, Japanese Patent Application Laid-Open No. 58-10987 discloses a technique for improving the tracking accuracy of a moving object.
0, a target tracking prediction system described in
776 is a speed prediction circuit.

First, the target tracking system described in Japanese Patent Application Laid-Open No. 58-109870 continues tracking of a moving object by one measurement processor based on information from a radar sensor system and an optical sensor system. While maintaining, predict the translatory movement of the moving object by another survey processor,
The curvature is calculated every moment from the past data locus. This makes it possible to determine the future position of the object on a straight line extension of the current motion vector of the object, and to determine the future position in consideration of the curvature of the motion.

However, according to this technique, once the capturing of the moving object fails, a continuous trajectory cannot be obtained even if the capturing of the object is possible thereafter. That is, unless a constantly moving object can be captured, tracking cannot be continued.

On the other hand, the speed prediction circuit described in Japanese Patent Application Laid-Open No. 1-182776 sequentially stores the position information and the speed information obtained by tracking when the position of the moving object is detected well. And even if the position of the object cannot be detected for a certain period of time, when the current position of the object can be detected,
The current position information is coordinate-transformed into orthogonal coordinates with the past position information as the origin and the speed direction at that time as 0 degree. That is, even if the object cannot be captured for a while with this technique, if the object can be captured later, the tracking can be continued.

However, in this technique, it is necessary to assume that the motion of the object is a simple linear motion such as a constant-velocity circular motion. However, if the object moves completely different from the assumed linear motion, tracking is performed. Can't continue. In addition, although the velocity vector of the object is predicted from the past position information and the current position information, there is no specific means for obtaining the current position information, and when the current position information cannot be obtained, If it is not possible to determine that they are the same object even if they are obtained by chance, tracking cannot be continued.

On the other hand, since it is assumed that the satellite orbits in a predetermined orbit at a predetermined period, a prediction calculation does not require much complicated calculation. In addition, the possibility that the satellite cannot be acquired is small. Therefore, even if the two related technologies are applied to satellite tracking, a large effect cannot be obtained for the cost, and there is almost no practical use.

[0020]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and has as its object to provide a satellite tracking system capable of improving the tracking accuracy.

[0021]

In order to achieve the above object, a satellite tracking system according to the present invention comprises an antenna for receiving a signal transmitted from a satellite and capturing the position of the satellite, and a satellite captured by the antenna. First storage means for storing the position of the satellite as satellite trajectory information, analysis means for obtaining a satellite orbit function at predetermined time intervals using the satellite trajectory information stored in the first storage means, and Second storage means for storing the obtained orbital function coefficients of the satellite for a plurality of times for each predetermined time, and optimizing the orbital function coefficients for the plurality of times stored in the second storage means for predicting the satellite; Evaluation means for determining a coefficient of an orbital function used for tracking; calculating means for calculating a satellite direction using an orbital function having a coefficient determined by the evaluation means; and a satellite direction calculated by the calculation means. Said a Controlled to direct the antenna means,
An antenna control unit for controlling the antenna means to acquire the position of the satellite at regular time intervals is provided.

Here, in order for the analyzing means to determine the orbit function of the satellite, satellite trajectory information for a predetermined time (at least one revolving cycle of the satellite) must be stored in the first storage means. For this reason, a determining means for determining whether or not the satellite trajectory information accumulated in the first storage means is equal to or longer than a predetermined time is provided, and processing is performed as follows in accordance with the determination result of the determining means. be able to.

(1) When it is determined that the trajectory information of the satellite is equal to or longer than a predetermined time, the analysis means obtains the orbit function of the satellite.

(2) When it is determined that the trajectory information of the satellite is less than the predetermined time, the antenna control unit controls the antenna means to acquire the position of the satellite based on a signal received from the satellite.

According to the satellite tracking method of the present invention, the coefficient of the satellite orbit function obtained by the analysis means is optimized by the evaluation means, and the predicted tracking is performed using the orbit function having the optimized coefficient. Accordingly, it is possible to converge the error of the prediction tracking of the satellite and improve the tracking accuracy.

Although various methods can be considered for optimizing the satellite orbit function by the evaluation means, usually, the average value of each coefficient of the satellite orbit function for a plurality of hours is taken. By doing so, the orbital function having the optimized coefficient converges to that of the original geosynchronous orbit, and the error in the predicted tracking of the satellite is reduced. In order to perform optimization by taking the average value of each coefficient of the orbit function of the satellite as described above, for example, the following two methods can be used.

(1) The evaluation means optimizes the orbit function of the satellite by averaging the coefficients of the orbit function of the satellite for a plurality of hours stored in the second storage means.

In this case, when the number of the orbit function coefficients of the satellite exceeds the capacity of the second storage means, the orbit function coefficients newly obtained by the analysis means are replaced with the oldest orbit functions. The coefficient of the trajectory function stored in the second storage means may be overwritten.

(2) The second storage means stores the coefficient of the orbit function for a plurality of times optimized by the evaluation means and the number of times the analysis means has obtained the orbit function of the satellite so far. And the evaluation means, every time the analysis means obtains a new trajectory function, ｛(stored optimization coefficient) × (stored number of analyzes)
+ (Coefficient of trajectory function newly obtained)｝ ÷ (number of times of analysis stored + 1) to optimize the trajectory function and newly optimize the storage contents of the second storage means. Is updated to the calculated coefficient, and 1 is added to the number of analyzes.

In this case, the storage capacity of the second storage means is small. Further, regardless of the number of times the trajectory function is obtained by the analysis means, the coefficient of the trajectory function can be optimized by the same formula and simple calculation. However,
Since the satellite performs orbit correction from time to time, it is necessary to update the orbit function whose coefficient is optimized in a certain period. Therefore, the calculation using the above formula is performed only for a certain number of times, and thereafter, ｛(stored optimization coefficient) × (stored number of analysis−
1) + (coefficient of orbital function newly obtained)｝ ÷ (the number of times of analysis stored) may be optimized.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The satellite described here is an example of a geostationary satellite placed in a geosynchronous orbit.

FIG. 1 is a functional block diagram of a satellite tracking system according to an embodiment of the present invention. This satellite tracking method includes a satellite trajectory information storage unit 11, a regression analysis processing unit 12, a regression coefficient storage unit 13, a regression coefficient evaluation unit 14, a satellite position / command angle calculation processing unit 15, an antenna control unit 16 And an antenna unit 17.

The satellite trajectory information storage section 11 sequentially stores the positions of the satellites captured by the antenna section 17 by a step track method or the like. The regression analysis processing unit 12
The orbit function of the satellite is obtained from the satellite trajectory information stored in the satellite trajectory information storage unit 11 by regression analysis using the least squares method, and the coefficient of the orbit function (hereinafter, referred to as “regression coefficient”).
Is sent to the regression coefficient evaluation unit 14.

The regression coefficient storage unit 13 stores the regression analysis processing unit 1
The regression coefficients obtained in step 2 are sequentially stored. The regression coefficient evaluation unit 14 determines an appropriate regression coefficient by optimizing the past regression coefficients already stored in the regression coefficient storage unit 13 and the current regression coefficients obtained by the regression analysis processing unit 12. Things.

The satellite position / command angle calculation processing section 15 obtains the orbit function of the satellite using the regression coefficient optimized by the regression coefficient evaluation section 14, and from this orbit function to the predicted position of the satellite and the antenna section 17. Is obtained. The antenna control unit 16 performs a step track for capturing the satellite every predetermined time in order to direct the antenna unit 17 to the command angle obtained by the satellite position / command angle calculation processing unit 15 and to obtain satellite trajectory information. In addition, control is performed to change the direction of the antenna unit 17. The antenna unit 17
It receives a signal sent from a satellite and acquires the position of the satellite.

Next, the operation of the embodiment of the present invention will be described. FIG. 2 is a flowchart showing the operation of the embodiment of the present invention.

First, determination means (not shown) determines whether or not past satellite trajectory information is stored in the satellite trajectory information storage unit 11 for at least one cycle (S11). This determination is made by counting the number of stored satellite track information. If the satellite trajectory information is not stored for one cycle, the antenna control unit 16 drives the antenna unit 17 by the step track method to acquire the position of the satellite (S18), and uses the position as the satellite trajectory information. The information is stored in the information storage unit 11 (M11).

On the other hand, when the satellite trajectory information is stored for one cycle or more, the satellite trajectory information for a certain period is read from the satellite trajectory information storage unit 11 (S12). Then, the regression analysis processing unit 12 obtains the orbit function of the satellite by linear regression analysis using the least squares method (S13).

Here, various orbital functions can be used for the satellite orbit function obtained by the linear regression analysis by the regression analysis processing unit 12 using the least squares method. For example, Equation 1 can be given.

[0040]

Y = A (1 + Et) sin (t + D) + Bt + C

Where y is the satellite position, sin (t) is 2
A sine function with a period of 4 hours, A is the sine function sin
(T) the amplitude, D is the phase of the sine function sin (t), E is the amplitude velocity deviation of the sine function sin (t), B is the velocity deviation,
C indicates a phase deviation.

The regression coefficients A, D, E, B, and C of the satellite orbit function obtained here are stored in a table provided in the regression coefficient storage unit 13 in the form shown in FIG. 3 (M12). .

Next, the regression coefficient evaluation unit 14 optimizes the regression coefficients from the regression coefficients stored in the regression coefficient storage unit 13 to determine the coefficients of the trajectory function (S14). Here, the regression coefficients are optimized by taking the average value of each regression coefficient stored in the regression coefficient storage unit 13.

Here, it is assumed that the regression coefficients for the time t = t _{0 to} t _n are obtained as shown in FIG. Since there are n + 1 pieces of satellite trajectory information, for example, A ′ in which the amplitude A is optimized
Is obtained by the equation of Expression 2.

A ′ = (A ₀ + A ₁ + A ₂ +... + A _n-1 + A
_n ) ÷ (n + 1) Other coefficients are obtained in the same manner.

Next, it is determined whether or not it is time to store new satellite track information (for example, every hour) (S15). If the memory time has not been reached, the satellite position
The command angle calculation processing unit 15 calculates the current satellite position using the orbit function having the regression coefficient optimized in step S14 and calculates the command angle to be given to the antenna unit 17 (S16). The command angle obtained here is input to the antenna control unit 16, and the antenna unit 17 is driven according to an instruction from the antenna control unit 16 (S17).

When it is determined in step S15 that the storage time of the new satellite trajectory information has come, the antenna unit 17 is driven by the step track method to acquire the position of the satellite (S18). It is additionally stored in the satellite trajectory information storage unit 11 as new satellite trajectory information (M11).

The above operation is repeated, and the prediction tracking of the satellite is performed by averaging and using the regression coefficients obtained by the regression analysis by the least squares method from the satellite trajectory information.

In the satellite tracking method of this embodiment, the satellite tracking accuracy is improved by averaging the coefficients of the satellite orbit function obtained by the linear regression analysis by the least squares method and converging and optimizing the error. be able to. That is, since the error of the satellite's orbit is almost the same in both north and south and altitude, by averaging the regression coefficients, the orbit function of the satellite converges to the original orbit, An error in prediction tracking can be reduced.

In the satellite tracking system of the above embodiment, the past regression coefficients are stored in the regression coefficient storage unit 13, and the regression coefficient evaluation unit 14 averages the past regression coefficients to obtain the regression coefficients. It has been described that the optimization is performed.
However, the number of trajectory function coefficients obtained by the regression analysis processing unit 12 may exceed the capacity of the regression coefficient storage unit 13. In such a case, the regression coefficient of the latest trajectory function obtained by the regression analysis processing unit 12 may be updated one after another by overwriting the regression coefficient stored in the regression coefficient storage unit 13 with the oldest. Good. The same applies when the number of satellite track information exceeds the capacity of the satellite track information storage unit 11.

As another optimization method, instead of storing a plurality of regression coefficients obtained by the regression analysis processing unit 12 in the regression coefficient storage unit 13, The average value of the regression coefficient obtained by the coefficient evaluation unit 14 is stored, and every time a new trajectory function is obtained by the regression analysis processing unit, {(storage average value) × (number of storage times) + (new regression coefficient)} ÷
By calculating (the number of storage times + 1), a new average value is obtained, the regression coefficient is newly optimized, sent to the satellite position / command angle calculation processing unit 15, and the content of the regression coefficient storage unit 13 is updated. It may be.

By doing so, the regression coefficient storage unit 1
3 requires a small storage capacity. Further, regardless of the number of obtained regression coefficients, optimized regression coefficients can be obtained by the same formula and simple calculation.

The formula of the linear regression analysis used in the present invention is not limited to the one described above, and various formulas can be used. The formula can be changed and used according to the accumulated amount of satellite trajectory information. However, the method of obtaining the orbit function of the satellite is not limited to the linear regression analysis using the least squares method. The method of optimizing the orbit function of the satellite is not limited to the method described above.

Although the above embodiment has been described with reference to the example of tracking a geostationary satellite placed on a geosynchronous orbit, the present invention is also applicable to the tracking of an artificial satellite placed on an orbit other than a geosynchronous orbit. It is possible to apply

[0054]

As described above, according to the satellite tracking method of the present invention, the error in the prediction tracking of the satellite is converged by converging the error of the coefficient of the orbital function of the satellite and optimizing the coefficient. Tracking accuracy can be improved.

Further, according to the satellite tracking system of the fourth or fifth aspect, the orbit function of the satellite can be converged to the original geosynchronous orbit, and the tracking accuracy is greatly improved.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a satellite tracking system according to an embodiment of the present invention.

FIG. 2 is a flowchart of a satellite tracking method according to an embodiment of the present invention.

FIG. 3 is a diagram showing a regression coefficient table according to an embodiment of the present invention.

FIG. 4 is a functional block diagram of a conventional satellite tracking system.

FIG. 5 is a flowchart of a conventional satellite tracking method.

[Explanation of symbols]

 11 satellite trajectory information storage unit 12 regression analysis processing unit 13 regression coefficient storage unit 14 regression coefficient evaluation unit 15 satellite position / command angle calculation processing unit 16 antenna control unit 17 antenna unit

Claims (5)

[Claims] An antenna means for receiving a signal transmitted from a satellite and acquiring the position of the satellite, a first storage means for storing the position of the satellite acquired by the antenna means as satellite trajectory information, Analysis means for obtaining a satellite orbit function at predetermined time intervals using the satellite trajectory information stored in the storage means, and a plurality of hours of storing the satellite orbit function coefficients for each predetermined time obtained by the analysis means. (2) storage means, evaluation means for optimizing orbit function coefficients for a plurality of times stored in the second storage means to determine orbit function coefficients to be used for predictive tracking of satellites, Calculating means for calculating the direction of the satellite by using an orbital function having the determined coefficient; controlling the antenna means to point in the direction of the satellite calculated by the calculating means; A satellite tracking system including an antenna control unit for controlling the stage to acquire the position of the satellite. And determining whether the information amount of the satellite track information stored in the first storage means is equal to or more than a predetermined time, wherein the determination means determines that the satellite track information is equal to or more than a predetermined time. 2. The satellite tracking system according to claim 1, wherein when it is determined that the satellite tracking function is the satellite orbit function, the analysis means obtains a satellite orbit function. 3. When the determining means determines that the trajectory information of the satellite is less than a predetermined time, the antenna control section controls the antenna means to acquire the position of the satellite based on a signal received from the satellite. The satellite tracking method according to claim 2, wherein the satellite tracking method is controlled. 4. The satellite orbit function is optimized by averaging the orbit function coefficients of the satellite for a plurality of hours stored in the second storage means. Item 4. A satellite tracking method according to any one of Items 1 to 3. 5. The second storage means stores the coefficients of the orbit function for a plurality of times optimized by the evaluation means and the number of times the analysis means has obtained the orbit function of the satellite so far. Each time the analysis means newly obtains a trajectory function, the evaluation means calculates the following equation: ｛(stored optimization coefficient) × (stored analysis count)
+ (Coefficient of trajectory function newly obtained)｝ ÷ (number of times of analysis stored + 1) to optimize the trajectory function and newly optimize the storage contents of the second storage means. 4. The satellite tracking method according to claim 1, wherein the updated coefficient is updated, and one is added to the number of times of analysis.