JP2522636Y2 - Antenna automatic tracking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an automatic tracking device for an antenna, and more particularly, to an automatic tracking device provided with a circuit for detecting an abnormality in automatic tracking.

[Conventional technology]

Generally, in satellite communication, an automatic tracking device that automatically controls the direction of the antenna so that the antenna always faces the satellite is provided. Usually, this device is configured to detect the level of a signal received through an antenna and to control the orientation of the antenna so that the level is maximized. Further, when the reception level drops below the level at which tracking is possible, automatic tracking is stopped to avoid malfunction of the antenna.

[Problems to be solved by the invention]

In the above-described conventional antenna automatic tracking device, the reception level itself may fluctuate due to the influence of rain attenuation and the like, so that the trackable level is lower than the nominal level in fine weather in consideration of the level fluctuation such as rain attenuation. Set to level. Therefore, when considering the tracking error angle, the tracking error is detected at a considerably large point, and the error cannot be detected at a narrow angle that does not affect the communication level, and the line margin cannot be increased. There is.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic antenna tracking device having an abnormality detection circuit that can increase a line margin.

[Means for solving the problem]

The antenna automatic tracking device of the present invention extracts each tracking error signal of the AZ axis and the EL axis based on the signal received from the antenna, and controls the direction of the antenna based on these signal levels. A low-pass filter that removes each mpulse noise from each error signal of the AZ axis and the EL axis; andcomparing each error signal voltage of the AZ axis and the EL axis from the low-pass filter with a reference voltage, respectively. Circuit that outputs a signal when is greater than the reference voltage, an OR circuit that takes the logical sum of the comparison outputs of the AZ axis and EL axis from these comparison circuits, and an automatic tracking mode A timer circuit for preventing a determination of a tracking error from being made for a certain period of time after the start; and a logical AND of the delayed tracking mode signal and the logical sum signal to obtain a tracking error. Characterized in that it comprises a tracking abnormality detection circuit constituted by the detection to the AND circuit.

[Action]

With the above-described configuration, when the error voltage of one axis exceeds the reference value during automatic tracking of the antenna, it is possible to detect an abnormality even before the reception level is significantly reduced, and the abnormality detection at a narrow angle can be performed. It is possible to increase the line margin.

〔Example〕

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

FIG. 1 is a block diagram of an embodiment of the automatic antenna tracking device of the present invention. In the figure, the antenna 1 is configured so that its direction is changed by a driving device 2, and a signal received by the antenna 1 can be decomposed by a tracking receiver 3 into error component voltages in the AZ axis and EL axis directions. . These error voltages are converted into speed command voltages by the antenna control device 4 and sent to the drive control device 5.
Controls the driving device 2 to always direct the antenna 1 toward the satellite.

In addition, the abnormality detection circuit 10 is obtained from the tracking receiver 3.
Each error voltage in the AZ-axis and EL-axis directions can be
The signals are filtered by a and 11b, and the filtered outputs are compared with predetermined reference voltages in comparison circuits 12a and 12b, respectively. The output of the comparison result is passed through the OR circuit 13 and input to one input terminal of the AND circuit 14.

On the other hand, the timer circuit 15 is a circuit for prohibiting the determination of the tracking abnormality due to the error voltage for a certain period of time from when the automatic tracking is started until the tracking error voltage settles to around 0 V. Input to the input terminal. The output of the AND circuit 14 is output to the antenna control device 4 as an abnormality detection signal.

According to the abnormality detection circuit 10, each of the error signals of the AZ axis and the EL axis is compared with the reference voltage in the comparison circuits 12a and 12b,
When the voltage is higher than the reference voltage, an abnormality detection signal is output. These outputs are ORed by the OR circuit 13 and then ANDed by the AND circuit 14 with the output of the timer circuit 15. Further, the timer circuit 15 outputs a pulse signal for prohibiting the determination of the tracking abnormality for a predetermined fixed time after the automatic tracking is started. Therefore, an abnormality detection signal is output to the output of the AND circuit 14 when at least one of the error signals of the AZ axis and the EL axis detects a tracking abnormality after the prohibition time of the timer circuit 15 has elapsed.

This abnormality detection signal is output to the antenna control device 4 as a drive stop signal to stop driving the antenna.

The low-pass filters 11a and 11b have a function of preventing external pulse noise from causing the comparator circuits 12a and 12b to malfunction.

FIG. 2 illustrates a case where the above operation is considered on a time axis. Curve E is the tracking error voltage from the tracking receiver. When automatic tracking is started at time t _o , the error voltage usually converges to around 0 V, but when _a tracking system error occurs at time ta and tracking in the satellite direction is not performed correctly, the error voltage increases again. I will. The protrusion in the curve is an external pulse noise. When the pulse size V ₀ is larger than the reference voltage E ₀ , the low-pass filters 11a and 11b do not stop the automatic tracking because the comparison circuits 11a and 11b determine that the tracking is abnormal.
After the pulse component is removed, comparison with a reference voltage is performed. The abnormality determination by comparison is started after the time T from the start of the automatic tracking to the settling of the error voltage by the timer circuit 15 has elapsed.

FIG. 3 shows an antenna pattern of a reception level with respect to an antenna angle, and a tracking error voltage in the AZ axis direction or the EL axis direction at that time. Since the antenna pattern A has a shape close to a quadratic curve, the reception level changes only slightly near the peak (Δl). In addition, since the reception level itself tends to fluctuate due to rain attenuation, etc., when the value L ₀ of the trackable level is set near the peak, it is difficult to make a comparison judgment, so the reception power of the antenna beam is normally reduced to half. This level is set to a low level that does not reach the side lobe patterns B and C from the level (the level lowered by 3 dB from the antenna beam peak point). Therefore, when the tracking is determined to be abnormal and the automatic tracking is stopped by the level comparison, the tracking error angle becomes a considerably large value (Δθ ₁ or Δθ ₂ ), and the received power value of the antenna decreases to at least half or less of the peak value. Would be. On the other hand, the tracking error voltage D
Regardless of the effect of rainfall, it is almost proportional to the antenna angle with 0 V when facing directly to the satellite direction, so it is easy to compare and judge the voltage, and set the trackable voltage E ₀ near the peak The tracking abnormality can be detected at a narrower angle (Δθ).

The present invention may be realized as a series of processing by a microcomputer. That is, the tracking error voltage from the tracking receiver is sampled at a certain fixed period, and after counting the time T from the arrival of the automatic tracking mode signal, the reference voltage E ₀ set in the internal memory and the tracking error voltage converted into a digital amount. Start comparison with V. If the result of the comparison is that V ≧ E ₀ occurs continuously for a certain number of times, it is determined that tracking is abnormal, and the automatic tracking may be stopped.

[Effect of the invention]

As described above, the present invention is divided from the received signal.
Since the tracking error is detected after comparing each error voltage of the AZ axis and the EL axis with the reference voltage, the tracking error is detected when the error voltage of one axis exceeds the reference value during automatic tracking of the antenna. Judgment stops automatic tracking. As a result, it is possible to detect an abnormality even before the reception level is greatly reduced, and it is possible to detect an abnormality at a narrow angle, thereby providing a large line margin.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the antenna automatic tracking device of the present invention, FIG. 2 is a time characteristic diagram of a tracking error voltage during automatic tracking, and FIG. 3 is a characteristic of an antenna reception level pattern and a tracking error voltage. FIG. DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Drive device, 3 ... Tracking receiver, 4 ... Antenna control device, 5 ... Drive control device, 10 ... Abnormality detection circuit, 11a, 11b ... Low-pass filter, 12a, 12b ... Comparison circuit, 13 ...
OR circuit, 14 ... AND circuit, 15 ... Timer circuit.

Claims (1)

(57) [Scope of request for utility model registration] An AZ axis based on a signal received from an antenna,
In an automatic antenna tracking device that takes out each tracking error signal on the EL axis and controls the direction of the antenna based on these signal levels, the AZ axis and the EL axis each remove pulse noise from each error signal. A high-pass filter, a comparison circuit that compares the error signal voltages of the AZ axis and the EL axis from the low-pass filter with a reference voltage, and outputs a signal when the error signal voltage is greater than the reference voltage, respectively. An OR circuit that calculates the logical sum of the comparison outputs of the AZ and EL axes, and a timer that delays the auto-tracking mode signal for a fixed time and does not judge the tracking error for a certain time after the auto-tracking starts. A tracking abnormality detection circuit comprising: a circuit; and an AND circuit for detecting a tracking abnormality by taking a logical product of the delayed tracking mode signal and the logical sum signal. Automatic antenna tracking device.