JPH0422475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a step track device, and more particularly to a tracking control method 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. .

Conventional technology Conventionally, this type of operation was performed by integrating the received signal level over a certain period of time while the antenna was stationary.
Remember L ₁ and then move the antenna to its rotation axis, e.g.
Drive the antenna by a small angle △θ around the X axis, measure the received signal level again after the antenna is stationary, store the value L ₂ , compare L ₁ and L ₂ , and calculate L ₁
If <L ₂ , drive the antenna in the same direction and L ₁
>L ₂ , drive the antenna in the opposite direction and L ₁ ≒L ₂
The same operation is repeated until (|L ₁ −L ₂ |<△L). When L ₁ ≒ L ₂ , 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 O 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 has recovered due to improvement in weather conditions more than the level that has decreased during that time, so the measured reception level will have increased. 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 starts from point O and the antenna is driven to point A, if the reception level itself does not change, if the antenna is further driven in the same direction, then B
The reception level decreases as indicated by the dot. In the next drive, the driving direction of the antenna is reversed and returns to point A again, and then the antenna is driven toward the center of the pattern like point C. 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, the reception level recovers and reaches the tracking possible level. If the antenna is driven in this direction, there is a possibility that the level will fall below the tracking possible level again.

FIG. 5 shows how this operation is repeated. In FIG. 5, when automatic tracking is restarted from a point on level M at which antenna tracking is restarted, if the antenna is driven to point I, which is in the same direction as before stopping tracking, the antenna will stop tracking. After that, even if the level recovers to point J, 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 in which the antenna is automatically directed in the direction of arrival of a received signal, and a difference is created between the reception level at which antenna tracking is started and the reception level at which this antenna tracking is stopped. It is characterized by the following.

Example 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, a step track device 1
, a reduction filter 2 for processing the received signal output from the antenna 11 via the receiving device 10, an integrator 3, a sampling processing section 4, a storage circuit 5, an arithmetic processing section 6, a timing circuit 7, and a stop level determination circuit 8. and a restart level determination circuit 9. This step track device 1 receives the output of the receiving device 10, controls the driving device 12, and controls the antenna 11.
The structure is such that it is always directed toward the satellite.

The output of the receiving device 10 is applied to an integrator 3 via a reduction 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, and the A/D
It is converted and stored in the storage circuit 5. The arithmetic processing unit 6 calculates the difference L ₂ in the received signal level before and after driving the antenna.
−L ₁ is calculated and its sign is determined, and the drive device 1
A control signal is sent to 2.

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 in one step, then the level will drop below the stop level again. This will prevent the antenna from being driven.

Effects of the Invention As explained above, 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, it is possible to achieve economical This has the advantage that a step track method can be used.

[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 apparatus shown in FIG. 1, FIG. 3 is a flowchart showing the operation of the conventional step track apparatus, and FIG. 5 is an antenna pattern characteristic diagram explaining step track operation.
The figure is an explanatory diagram when automatic tracking is impossible. Explanation of symbols of main parts, 3...Integrator, 5...
Memory circuit, 6... Arithmetic processing unit, 8... Stop level determination circuit, 9... Resume level determination circuit, 11...
Antenna, 12... drive device.

Claims (1)

[Claims] 1. By driving the antenna stepwise at a predetermined angle, comparing the reception level before and after the drive, and repeatedly driving the antenna in the direction where the reception level increases, the arrival direction of the received signal is automatically determined. This is a tracking control method for a step track device in which the antenna is directed to the direction in which the antenna is driven in one step. A tracking control method that is characterized by making the level slightly higher than the level that sometimes drops.