JPH02266702A - Detector for azimuth and elevation angle of parabolic antenna - Google Patents

Abstract

PURPOSE:To attain the improvement of the display accuracy of an azimuth angle and the reduction of a cost regardless of the height of the axis of an elevation angle by using the deflection of light in the measurement of the azimuth angle. CONSTITUTION:The light from a laser oscillator 6 housed in a rotational mechanism part 2 directly becomes a deflecting beam after passing a deflector 7, and is controlled so as to irradiate the intermediate part between two diodes of an optical detector 9 by a motor 15. In order words, control such that a half mirror 10 fixed on the ground can be always irradiated at right angles with an optical beam is applied even when the axis of the elevation angle of an antenna is moved, and an angle detector 17 directly connected to a movable bearing for attack angle detects the attacked angle of the main reflecting mirror 1 of the antenna. Namely, linearly deflected light passing the half mirror 10 is separated to two linearly deflected light by a deflection prism 11, and projects an optical detector 12, respectively, and a rotational mechanism part 3 is turned by a motor 16 following in the deflecting direction of the optical beam, and an angle detector 18 detects the azimuth angle of the main reflecting mittor 1. In such a way, it is possible to improve the display accuracy of the azimuth angle regardless of the height of the axis of the attack angle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a parabolic antenna azimuth and attack angle detection device for detecting the azimuth and attack angle of a parabolic antenna with high precision.

(Prior art) By the way, in the fields of radio astronomy and VLBI (Very Long Baseline Interferometer), the observation frequency of radio sources is increasing, and the need to observe even weaker radio sources has led to the increase in the size of parabolic antennas. Caliberization is progressing.

Such parabolic antennas require the beam axis of the antenna to be directed toward the radio wave source with high precision, requiring an angle detection method that is more than an order of magnitude more precise than the angle detection method used in conventional satellite communications. .

As a parabolic antenna azimuth and angle of attack detection device that satisfies this requirement, there is a so-called collimator tower one-type device as shown in Mitsubishi Electric Ekakan Vol. 56, No. 7, Page 15. That is, in this device, a collimator tower is erected in the center of a parabolic antenna, an autocollimator device with an azimuth-angle-of-attack mount is provided on the top of the collimator tower, and the autocollimator device allows the main body of the parabolic antenna to be The position of the plane reflector attached to the back of the reflector is detected. Through this position detection, the azimuth and angle of attack of the parabolic antenna are detected.

Another example of the conventional parabolic antenna azimuth and angle of attack detection device is shown in FIG. It is directly attached to the rotation axis that changes the rotation axis, and the rotation angle of the parabolic antenna due to the rotation of the rotation axis is directly detected.

(Problems to be Solved by the Invention) However, the above-mentioned one-type collimator tower has a drawback in that when the angle of attack axis of the parabolic antenna becomes high, the display accuracy of the azimuth angle deteriorates.

In addition, there is a further drawback that the collimator tower of the parabolic antenna must be erected, and the cost for this erecting takes up a large proportion of the cost.

In addition, in the case where the azimuth angle detector 19 and the angle of attack detector 20 are directly attached to the rotation axis, many structures are interposed between the main reflecting mirror and each angle detector 19, 20, and the structure There is a drawback that an error occurs between the directivity angle of the main reflecting mirror to be actually detected and the angle detector due to thermal deformation of the object, its own weight, elastic deformation due to wind pressure, etc. In particular, as the diameter of the parabolic antenna becomes larger, the treetop body also becomes larger and the error tends to increase.

An object of the present invention is to solve the above-mentioned drawbacks, and it is possible to improve the display accuracy of the azimuth angle regardless of the height of the angle of attack axis, and to reduce the cost. An object of the present invention is to provide a parabolic antenna azimuth and angle of attack detection device that can suppress the occurrence of measurement errors due to thermal deformation of a structure, elastic deformation due to its own weight, etc.

(Means for Solving the Problem) The above problem is achieved by rotating the parabolic antenna in each direction and detecting the rotation angle when adjusting the azimuth and angle of attack of the parabolic antenna. A parabolic antenna azimuth and angle of attack detection device configured to detect a parabolic antenna, which includes a reflector, first and second rotation mechanism parts, first and second rotation drive means, and first and second rotation drive means. 2 rotation angle detector, the reflector is fixed on the ground and reflects and transmits the laser beam, and the first rotation FFI ellipse is provided on the back of the parabolic antenna. It is supported by a first bearing so as to be freely rotatable in the direction of the angle of attack, and this first rotating mechanism includes a laser oscillator that oscillates a laser beam, and a polarizing means that polarizes the laser beam in a specific direction. , a first light-receiving element into which the laser light from the laser oscillator is input via the reflector is attached, and the first rotation driving means is attached with a first light-receiving element through which the laser light from the laser oscillator is input into the first light-receiving element. The rotation angle of the parabolic antenna around the first bearing is calculated based on the amount of laser light, and
The rotation mechanism is rotated by the rotation angle in a direction opposite to the rotation direction of the parabolic antenna, and the first rotation angle detector is attached to the first rotation drive means and A rotation drive angle is detected, and the second rotation 61#1 portion is supported by a second bearing provided on the back surface of the parabolic antenna to freely rotate in the azimuth angle direction,
The second rotating mechanism includes a polarizing prism into which the laser beam from the laser oscillator is input via the reflector, and a second light receiving element into which the laser beam output from the polarizing prism is input. is attached, and the second rotation driving means calculates a rotation angle of the parabolic antenna around the second bearing based on the amount of laser light input to the second light receiving element. The second
The rotation mechanism is rotated by the rotation angle in a direction opposite to the rotation direction of the parabolic antenna, and the second rotation angle detector is attached to the second rotation drive means and This problem can be solved by detecting the rotational drive angle.

(Example) An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.

The entire structure includes a first rotation mechanism section 2 attached to the back surface of the antenna 1 via a bearing 4 as a first bearing of the present invention that is movable in the direction of the angle of attack, and a first rotation mechanism section 2 that rotates in the direction of the azimuth axis with respect to the ground. A second rotation mechanism unit 3 attached via a bearing 5 as a second bearing of the present invention, and differential amplifiers 13 and 14 that generate signals for rotating them in the desired direction.
The drive motors 15 and 16 as the first and second rotation drive means of the present invention and the first and second rotation angle detectors of the present invention for detecting the rotation angle of the upper and lower rotation mechanism parts. It consists of high-precision angle detectors 17 and 18.

Light from a laser oscillator 6 housed in the first rotation mechanism section 2 passes through a polarizer 7 as a polarizing means of the present invention and becomes a completely linearly polarized beam. After passing through the semi-transparent mirror 8, this beam passes through the semi-transparent Sf as a reflector of the present invention fixed to the ground.
i 10, and about half of the power is reflected back in the original direction. This reflected light returns to the first rotating mechanism section 2 again, is bent at a right angle by a semi-transparent mirror 8, and illuminates a photodetector 9.

This photodetector 9 consists of a two-split photodiode with outputs 1°P and 2. Now, if the intensity distribution of the light beam is bell-shaped (usually glass-shaped), each photodiode p
The output of ell p,2 is as shown in FIG. That is, the center of the light beam and the photodiode p el+ p,2
When the centers of the diode coincide with each other, the diode output becomes maximum. Since the positions of the two diodes P and 1° Pe2 are slightly shifted, the positions of the respective light beams that produce the maximum output are shifted. Then, when the outputs of the two photodiodes are subtracted by the differential amplifier 13, the output becomes OV when the light beam is irradiating the middle of the two diodes p,,,p,2, and the output is OV from the middle point. The voltage is proportional to the deviation.

This voltage is applied to the drive motor 1 through an appropriate control filter.
5, the light beam is controlled to illuminate the middle of the two diodes at any time. That is, even if the angle of attack axis of the antenna moves, the light beam is controlled so that it always irradiates the semi-transparent mirror 10, which is not fixed to the ground, at right angles. Therefore, the high-precision angle detector 17 is directly connected to the movable bearing for the angle of attack.
The angle indicated by corresponds to the angle at which the main reflector of the antenna rotates with respect to the ground.

On the other hand, the polarization of light is used to measure the angle of the azimuth axis.

That is, the linearly polarized light that has passed through the semi-transparent mirror 10 is separated into two linearly polarized lights by the polarizing prism 11, and each of them illuminates the photodetector 12. Here, when the polarizing prism 11 is fixed and the polarization direction of the incident light beam is rotated, the two diodes P al constituting the photodetector 12
+ P a2 output is shown in FIG. 3, polarizing prism 11
If the polarization direction of the input optical beam with respect to the reference axis is θ, the outputs of the two diodes, V, , V,2, are:
I CO32θ).

Note that K is a constant determined by the detection sensitivity of the photodiode. Then, when these outputs are subtracted by ■, 1°■, and 2 by the differential amplifier 14, the output V is V=2KCO3
It becomes 2θ.

That is, when θ is 45°, 135°, 225° and 31
At 5°, the output V becomes OV.

This voltage V is passed through a suitable control amplifier to the drive motor 16.
When the light beam is supplied to the light beam, the second rotation mechanism section 3 rotates following the direction of the deflection of the light beam. That is, when the azimuth axis of the parabolic antenna rotates and the first rotation mechanism section 2 rotates, the second rotation mechanism section 3 also rotates to follow. Therefore, the angle represented by the high-precision angle detector 18 attached to the second rotation mechanism 3 corresponds to the angle that the main reflecting mirror of the antenna makes with respect to the ground.

Here, as shown in Fig. 3, there are two stable points in the tracking loop of the azimuth system. It is made to follow only stable points. This processing is executed by a processing routine of an angle display circuit using a microprocessor or the like.

Furthermore, in this embodiment, polarized light is used to measure the azimuth angle. Generally, when light propagates through the atmosphere, the plane of polarization of the light beam changes due to changes in the refractive index and scattering by dust in the atmosphere. In this example, the propagation distance is on the order of several tens of meters, and the influence of scattering is greater than that of refractive index fluctuation.

Therefore, a simple duct for dust protection is provided in the propagation path of the light beam to suppress scattering fluctuations.

(Effects of the Invention) As explained above, according to the present invention, the display accuracy of the azimuth angle can be improved regardless of the height of the angle of attack axis.
In addition, it is possible to reduce costs, and at the same time, it is possible to suppress the occurrence of measurement errors due to thermal deformation of the horizontal object, elastic deformation due to its own weight, etc.

Oscillator, 7... Polarizer, 8... Semi-transparent mirror, 9... Photodetector, 10... Semi-transparent mirror, 11... Polarizing prism,
12... Photodetector, 13.14... Differential amplifier, 1
5.16... Drive motor, 17.18... High precision angle detector.

Claims (1)

[Claims] When adjusting the azimuth and angle of attack of the parabolic antenna, the parabolic antenna is rotated in each direction and the angle of rotation is detected to detect the azimuth and angle of attack of the parabolic antenna. In the azimuth and angle of attack detection device for a parabolic antenna, a reflector, first and second rotation mechanisms, and first and second rotation mechanisms are provided.
and a first and second rotation angle detector, the reflector is fixed on the ground and reflects and transmits laser light, and the first rotation mechanism section includes: , is supported by a first bearing provided on the back surface of the parabolic antenna so as to be rotatable in the direction of the angle of attack, and the first rotation mechanism includes a laser oscillator that oscillates a laser beam, and a laser oscillator that oscillates the laser beam. A polarizing means for polarizing the laser light in a specific direction, and a first light receiving element into which the laser light from the laser oscillator is input via the reflector are attached, and the first rotation driving means: The rotation angle of the parabolic antenna around the first bearing is calculated based on the amount of laser light input to the first light receiving element, and the first
The rotation mechanism is rotated by the rotation angle in a direction opposite to the rotation direction of the parabolic antenna, and the first rotation angle detector is attached to the first rotation drive means and The rotation drive angle is detected, and the second rotation mechanism is supported by a second bearing provided on the back surface of the parabolic antenna to freely rotate in the azimuth angle direction. A polarizing prism into which the laser beam from the laser oscillator is input via the reflector, and a second light receiving element into which the laser beam output from the polarizing prism is input are attached to the mechanism part, The second rotation driving means calculates the rotation angle of the parabolic antenna around the second bearing based on the amount of laser light input to the second light receiving element, and calculates the rotation angle of the parabolic antenna around the second bearing.
The rotation mechanism section is rotated by the rotation angle in a direction opposite to the rotation direction of the parabolic antenna, and the second rotation angle detector is attached to the second rotation drive means and is connected to the second rotation drive means. A parabolic antenna azimuth and angle of attack detection device characterized by detecting a rotational drive angle.