JPS5935201B2 - antenna mount device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antenna mount device used for tracking an artificial satellite from a mobile station such as a ship.

A conventional antenna mount device that is relatively simple is a two-axis AZ-EL mount system or an X-Y mount system.

Among both types, the AZ-EL mount type is the EL axis (
A counterweight is required for the axis horizontal to the ground), but almost no counterweight is required for the AZ axis (axis perpendicular to the ground). It is small and lightweight compared to the X-axis and the Y-axis perpendicular to it, making it suitable for mobile stations. However, when tracking a satellite near the zenith (AZ-axis direction), the rotational angular velocity of the AZ-axis is smaller than the relative movement angular velocity of the satellite. This has the disadvantage that tracking is impossible within a certain area near the zenith.

To overcome this drawback, when tracking a satellite near the zenith, a method can be considered in which the AZ axis is tilted at a certain angle from the vertical axis. In the method of tilting the AZ axis by a certain angle (β), the tilt angle (β) becomes considerably large, and the dimensions of the antenna and the radome that covers the mounting device may not be much different from those of the X-Y mount method. There is.

In other words, in the case of the above mounting method, if the maximum roll angle of the ship is ±θR1 and the maximum pitch angle is ±θP, when the elevation angle becomes larger, it becomes necessary to tilt the AZ axis, and the tilt angle is (forward or (if later tilted) or should be.

When considering small vessels of at least 100 tons, the roll angle θR may reach a maximum of 45°, but the pitch angle θP
never exceeds 15°.

Therefore, the inclination angle β may be smaller if it is tilted in the front-rear direction, but even in that case, the required inclination angle becomes quite large.

In order to eliminate the drawbacks of the conventional AZ-EL mount type antenna mount device as described above, the present invention tilts the AZ axis slightly toward the stern when the satellite is in the bow direction of a mobile station such as a ship, and vice versa. When the satellite is towards the stern, AZ
By tilting the shaft slightly toward the bow, it is possible to eliminate the inability to track at a small tilt angle.

The present invention will be described in detail below using the drawings.

FIG. 1 is an external view showing an embodiment in which an antenna is mounted on an antenna mount device according to the present invention. In the figure, 1 is an antenna, 2 is a counterweight, 3 is an EL axis rotation mechanism, 4 is an AZ axis, and 5 is an It is an AZ-axis rotation mechanism.

Reference numeral 6 denotes an AZ-axis tilting mechanism, which includes a tilting drive motor 7, a deceleration mechanism 8, and a tilt angle detection instrument 9.

The antenna 1, counterweight 2, EL axis rotation mechanism 3, and AZ axis 4 described above are exactly the same as those of the conventional AZ-EL type mount.

FIG. 2 is a block diagram showing a circuit for controlling the AZ-axis tilting mechanism of the antenna mount device according to the present invention. In the figure, 11 is an output element for satellite azimuth information, and 12 is an output element for heading information, which is a pixel. 11 and 12 are connected to a subtraction circuit 13, and the output of the subtraction circuit 13 is applied to the AZ-axis tilt mechanism 6 via a determination circuit 14 and a tilt drive circuit 15.

The AZ-axis tilting mechanism 6 uses a drive motor 7 and a deceleration mechanism 8, as described in FIG.

Next, FIG. 3 is a diagram for explaining the relationship between the relative azimuth angle of the satellite, the roll angle and pitch angle of the ship, and the necessary inclination angle. In the figure, A is an elliptical arc indicating the roll angle θR, is an elliptical arc indicating the roll angle -θR, B is an elliptical arc indicating the pitch angle 2θP, ``is an elliptical arc indicating the pitch angle -2θP, P is a point indicating the direction of the satellite, D is a circle indicating the elevation angle θ, and E is the relative azimuth angle A straight line indicating ψ, 01 is A when the ship is tilted by θP toward the bow.
A point indicating the direction of the Z axis, 02 a point indicating the direction of the AZ axis when tilted by θP toward the stern, and F a straight line indicating the pitch angle O°.

When the AZ axis is tilted toward the bow by θP, the satellite may cross the vicinity of point 01 due to the ship's roll (±θR) and pitch (±θP) and become untrackable due to the satellite position P. enters the area surrounded by AFA'.

Similarly, if the AZ axis is tilted towards the stern by θP,
Tracking may become impossible when the satellite position P enters the area surrounded by AB deception.

Therefore, when the satellite position P enters the area AF, α, A
Loss of tracking can be avoided by tilting the Z-axis by θP toward the stern (backward), and when the satellite position P enters the area ABA'F, by tilting the AZ-axis by θP toward the bow (forward), but otherwise. In the area of , it can be tilted in either direction, so to simplify the judgment, when the satellite position P is ahead of the straight line F, tilt the AZ axis backward, and when the satellite position P is behind the straight line F, tilt the AZ axis backward. All you have to do is tilt the AZ axis forward.

However, ships also have yawing (approximately ±5 degrees), so in order to prevent the AZ-axis inclination direction from frequently switching due to yawing, the judgment threshold for switching from front to rear and the judgment for switching from rear to front are set. The threshold needs to be changed slightly, and the inclination angle accordingly needs to be made slightly larger than θP.

That is, conditions for switching from forward inclination to backward inclination: 1ψ1<90°−ε (3) Conditions for switching from backward inclination to forward inclination: 1ψ1>90°1ε (4) Inclination angle:
β−±(θP+δ) (5) However, ε−δ! =i5° (6) Also ε
is the depth of hysteresis of the determination circuit provided to prevent the AZ-axis inclination direction from frequently switching due to yawing of the ship.

This ε is determined from the magnitude of the ship's yawing, the responsiveness of the AZ-axis inclination direction switching control, etc., and is set in advance within the determination circuit.

A circuit that operates as described above is constructed as shown in FIG.

That is, the output ψ1 of the satellite azimuth output element 11 and the output ψ2 of the bow azimuth output element 12 are subtracted from each other by the subtraction circuit 13 and converted into a relative azimuth (ψ-ψ1-92).
The signal is guided to a determination circuit 14.

The judgment circuit 14 consists of a magnitude comparison circuit and a logic circuit.
When the axis is tilted forward, it is determined whether the condition of equation (3) is satisfied, and if it is true, the drive motor 7 is rotated through the drive circuit 15, and the tilt angle of the AZ axis 4 is adjusted backward by θP+ε( However, the ship is tilted until θP is the maximum pitch angle of the ship.

When the AZ axis is tilted backward, it is determined whether the condition of equation (4) is satisfied, and if it is true, the drive motor 7 is rotated in the opposite direction to the above through the drive circuit 15, and the AZ axis 4 is tilted forward. Tilt until the angle becomes -(θP+ε).

Information on which direction the AZ axis is tilted is provided from the tilt angle detection instrument 9 to the determination circuit 14.

Note that θR2θP and ε are set to predetermined values within the determination circuit 14.

For the satellite azimuth output element 11, a synchronizer or potentiometer is used in the case of an analog system, and a rotary switch or register is used for the digital system, and for the heading information output element 12, a ship's gyro compass is used.

For the inclination angle detection instrument 9, a synchronizer or potentiometer can be used in the case of an analog method, and a low-resolution encoder, etc. can be used in the case of a digital method, but it is only necessary to detect two angles: + (θP + ε) and - (θP + ε). Therefore, a simple limit switch can also be used.

According to the present invention, light is −45°, θP=15°
Even in the case of the above-mentioned example of a small ship, the inclination angle of the AZ axis can be set to a small value of about ±(θP+ε)−i±20°, which can eliminate the untrackable state and downsize the mount device. be able to.

[Brief explanation of the drawing]

FIG. 1 is an external view showing an embodiment in which an antenna is mounted on an antenna mount device according to the present invention, FIG. 2 is a block diagram showing a circuit for controlling the AZ-axis tilting mechanism of the antenna mount device according to the present invention, and FIG. Figure 3 is a line section for explaining the relationship between the satellite's relative azimuth, the ship's roll and pitch angle, and the required inclination angle. In the figure, 6 is the AZ-axis tilting mechanism, 7 is the tilting drive motor, and 8
9 is a deceleration mechanism, 9 is an inclination angle detection instrument, 11 is an output element for satellite azimuth information, 12 is an output element for heading information, 13
14 is a determination circuit, and 15 is a slope drive circuit.

Claims (1)

[Claims] 1. An output element for satellite azimuth (ψ1) information, an output element for bow azimuth (ψ2) information for a mobile station such as a ship, etc. −ψ2); a determination circuit comprising a magnitude comparison circuit and a logic circuit for determining whether the satellite is in the bow or stern direction of the mobile station based on the output of the subtraction circuit; It is equipped with an AZ-axis tilting mechanism including a tilting drive circuit driven by the output, a drive motor driven by the output of the tilting drive circuit, and a tilt angle detection instrument. ε is the depth of the hysteresis of the judgment circuit provided to prevent the AZ-axis inclination direction from frequently switching due to the yawing of the ship. It is determined from the responsiveness of the control, etc., and is preset inside the judgment circuit.) It is determined whether the condition () is satisfied, and if it is satisfied, the drive motor is rotated through the drive circuit, and the AZ axis is tilted backward. Tilt until the angle becomes θ + ε (however, θ2 is the maximum pitch angle of the ship), and when the AZ axis is tilted backward, 1ψl
〉Determine whether the condition of 90° + ε is satisfied or not, and if it is, the drive motor is rotated in the opposite direction to the above through the drive circuit to tilt the AZ axis forward until the inclination angle becomes -(θ, +ε). An antenna mount device characterized by: