JPS61215975A - Tracking control system of step track device - Google Patents

Abstract

PURPOSE:To prevent a tracking error even when the change occurs at the incoming electric wave by providing the difference between the receiving level to start an antenna tracking and the receiving level to stop an antenna tracking. CONSTITUTION:The output of a receiving device 10 is applied through an LPF 2 to an integrator 3, integrated for a constant time while an antenna 11 is standstill, next, sampling-processed 4 and stored 5. An arithmetic processing part 6 calculates the difference of a receiving signal level before and after the antenna is driven, decides the positive and negative and transmits the control signal to a driving device 12. Presently, when the automatic tracking is stopped, a stop level deciding circuit 8 is operated, and the automatic tracking is restarted from the untrackable condition, the difference between the level to restart the tracking and the level to stop the tracking is set larger than the level to descend when the antenna 11 drives by one step, and again, it can be prevented that the antenna 11 is driven to a stop level or below. Even when the change of the incoming electric wave strength is large, the increase in the tracking error can be prevented beforehand.

Description

[Detailed Description of the Invention] The present invention relates to a step track device, and in particular tracking control in a step track device used in an earth station antenna for geostationary satellites in a frequency band with high rainfall attenuation such as sub-millimeter waves. Regarding the method.

Prior Art Conventionally, this type of operation integrates the received signal level over a certain period of time with the antenna stationary, stores the value, and
Next, the antenna is driven by a small angle Δθ around its rotation axis, for example, the
Compare 2 and 1. If L2, drive the antenna in the same direction, and if L > L2, drive the antenna in the opposite direction, and perform the same operation until L"=:L (IL - L21<ΔL). The process is repeated. When - is reached, the drive shaft is switched and the operation is repeated. The flowchart in FIG. 3 shows the flow of this operation.

FIG. 4 shows the operation of the conventional step track device when the reception level is restored. The parabola in the figure is an antenna pattern, and represents how the reception level gradually recovers from the level at the start of automatic tracking. A parabola S shows the automatic tracking start level, and a parabola T shows the clear weather level.

When the reception level is restored, a tracking error as shown by the arrow from point 0 to point A in FIG. 4 may occur. This is because when the reception level recovers quickly, even if the antenna is driven in the direction of decreasing the level, the level of the antenna pattern itself will have recovered more than the level that decreased during that time due to improvement in weather conditions. The received level has increased, so the antenna is further driven in the same direction, and if this is repeated, the antenna will be driven away from the pattern.

In Figure 4, when automatic tracking is started from point 0 and the antenna is driven to point Δ, if the reception level itself does not change, if it is driven further in the same direction, the reception level will drop as shown at point 8. . In the next drive, the driving direction of the antenna is reversed and returns to point A, and then the antenna is driven toward the center of the pattern like point 0. However, if the reception level suddenly drops before the antenna returns to point A, the antenna stops tracking at point D, which is below the tracking possible level.

At this point, if there is no or small difference between the reception level that restarts tracking and the reception level that stops tracking,
If the reception level recovers and reaches the trackable level, and the antenna is driven in the opposite direction to the satellite direction as shown by arrow E, there is a possibility that it will fall below the trackable level again.

FIG. 5 shows how this operation is repeated. In FIG. 5, when automatic tracking is restarted from a point at the level Ml at which antenna tracking is restarted, if the antenna is driven to a point in the same direction as before stopping tracking, the antenna will stop tracking. After that, even if the level recovers to point 8, if the motor is driven again in the same direction as before stopping, it will reach point K and become stopped again.

If this operation is repeated, the antenna may be driven outside the tracking range.

Purpose of the Invention In order to prevent such antenna driving, the present invention provides a tracking control method that drives the antenna so that even if the antenna is driven in the same direction as before stopping, the antenna does not fall below the stopping level again. With the goal.

Structure of the Invention The tracking control method according to the present invention involves driving the antenna stepwise at a predetermined angle, comparing the reception level before and after the driving, and repeatedly driving the antenna in the direction where the reception level increases. A tracking control method for a step track device that automatically orients the antenna in the direction of arrival of a received signal by creating a difference between the reception level that starts antenna tracking and the reception level that stops this antenna tracking. It is characterized by the following.

Marutanetan Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, the step track device 1 includes an antenna 11
A low-pass filter 2. that processes the received signal output from the receiving device 10 through the receiving device 10. It consists of an integrator 3.1 node numbering processing section 4, a storage circuit 5, an arithmetic processing section 6, a timing circuit 7, a stop level judgment circuit 8, and a restart level judgment circuit 9. is input, and the drive device 12 is controlled to always direct the antenna 11 toward the satellite.

The output of the receiving device 10 is applied to an integrator 3 via a low-pass filter 2, and is integrated for a certain period of time while the antenna 11 is stationary. This integral output is sampled by the sampling processing section 4, A/D converted, and stored in the storage circuit 5. The arithmetic processing unit 6 calculates a difference L2-11 between the received signal levels before and after the antenna is driven, determines whether the difference is positive or negative, and sends a control signal to the drive device 12.

Here, when automatic tracking is stopped, a stop level determination circuit 8 is activated, and when automatic tracking is restarted from a state in which tracking is impossible, a restart level determination circuit 9 is activated. In other words, as shown in Figure 2, if the difference between the level Y at which tracking is restarted and the level Z at which tracking is stopped is set to be greater than the level that drops when the antenna is driven once, the level will drop below the stop level again. This means that it is possible to prevent the antenna from being driven.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, according to the present invention, even when fluctuations in the intensity of incoming radio waves are large, increases in tracking errors can be prevented, and even in earth station antennas in the sub-millimeter wave band where rainfall attenuation is large.
An economical step-track method can be used effectively.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the operation of the step track of the device shown in FIG. 1, FIG. 3 is a flowchart showing the operation of the conventional step track device, and FIG. FIG. 5 is an antenna pattern characteristic diagram explaining the step tracking operation, and is an explanatory diagram when automatic tracking is impossible. Explanation of symbols of main parts 3...Integrator 5...Memory circuit 6...Nose performance processing section 8...Stop level judgment circuit 9... ... Resumption level determination circuit 11 ... Antenna 12 ... Drive device

Claims (2)

[Claims] (1) By driving the antenna in steps at a predetermined angle, comparing the reception level before and after the driving, and repeatedly driving the antenna in the direction where the reception level increases, the reception signal is automatically adjusted. A tracking control method for a step track device in which the antenna is directed in the direction of arrival, characterized in that a difference is provided between a reception level at which antenna tracking is started and a reception level at which this antenna tracking is stopped. Tracking control method. (2) The tracking control method according to claim 1, wherein the difference in the reception level is set to be greater than a level that decreases when the antenna is driven once.