JP3895455B2 - Antenna system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna system, and more particularly to an antenna system that is mounted on a moving body such as a vehicle and captures and tracks radio waves from satellite equipment.
[0002]
[Prior art]
When receiving satellite radio waves transmitted from communication satellites or broadcast satellites, a high gain antenna with sharp directivity is required on the ground station side in order to obtain good reception quality.
Therefore, in order to receive a satellite radio wave by mounting an antenna on a moving body, it is necessary to first search the direction of the satellite and direct the antenna directivity toward the satellite.
That is, it is necessary to monitor the change in the received intensity while rotating the antenna in the azimuth direction with respect to the entire space, and to direct the antenna in the direction in which the received intensity is maximized. Hereinafter, such an operation is referred to as a capture operation. This capture operation is also necessary when the radio wave from the satellite cannot be received due to a radio wave interruption or the like during reception and is re-captured, or when the satellite to be received is switched. .
[0003]
And after the capture operation is completed, it is necessary to change the antenna directivity direction relative to the moving body's attitude change that occurs as the moving body moves, so that the antenna always faces the target satellite. There is. Hereinafter, such an operation is referred to as a tracking operation.
[0004]
FIG. 5 is a block diagram showing an example of the configuration of a conventional antenna system of this type that automatically performs the above-described capturing operation and tracking operation.
In FIG. 5, 50 is a control program, 51 is a rotation control unit, 52 is an antenna rotation mechanism, 53 is an antenna, 54 is a reception channel setting unit, 55 is a detection unit, and 56 is a signal level (hereinafter referred to as S level) detection. , 57 is a comparison circuit, 58 is a fine rotation control unit, 59 is an antenna angle detection unit, 60 is an angle / S level storage unit, 61 is a peak angle detection unit, and 62 is an antenna beam switching unit.
[0005]
FIG. 6 is a flowchart showing the capturing operation of the antenna system shown in FIG.
Under the control of the control program 50, the rotation control unit 51 operates the antenna rotation mechanism 52, the antenna 53 starts rotating in the azimuth direction, and the capturing operation is started.
The reception radio wave from the antenna 53 is input to the reception channel setting unit 54, and the radio wave of the desired reception channel is detected by the detection unit 55. The reception level detection unit 56 determines the reception electric field strength from the output of the reception channel setting unit 54. The detected information is input to the comparison circuit 57.
In the comparison circuit 57, the S level information indicating the received electric field strength is compared with a predetermined threshold value, and when a desired wave exceeding a predetermined level is detected, the rotation control unit 51 operates the antenna rotation mechanism 52 to Stop the rotation and end the capture operation.
[0006]
When the capturing operation is finished, the control program 50 starts a tracking operation.
In this tracking operation, first, under the control of the control program 50, the micro-rotation control unit 58 instructs the antenna rotating mechanism 52 to always rotate the antenna 53 around ± the micro-angle around the current stop angle. Alternatively, the antenna remains fixed, and the antenna beam switching unit 62 is instructed to swing the antenna beam at a minute angle.
The azimuth angle of the rotating antenna 53 or the azimuth angle of the antenna beam is always detected by the angle detection unit 59 and this information is input to the angle / S level storage unit 60.
On the other hand, the angle / S level storage unit 60 is input with S level information indicating the received electric field intensity from the S level detection unit 56, and is accompanied by a minute rotation of the antenna 53 or a change in the minute angle of the antenna beam. S level information corresponding to each angle is stored and updated.
[0007]
The peak angle detection unit 61 constantly monitors the maximum reception level. When the maximum reception level changes from the current set center angle (rotation center angle), the rotation control unit 51 reads the changed angle. The rotation control unit 51 operates the antenna rotation mechanism 52 to rotate the antenna 53 to an angle at which the signal reception level becomes maximum, and this time, the angle is set as a set central angle, and the minute rotation control unit 58 is rotated. Rotates the antenna 53 slightly again, or the antenna beam switching unit 62 swings the antenna beam at a minute angle.
By repeating such an operation, a tracking operation for always facing the antenna to the satellite is performed even if the posture of the moving body is changed.
[0008]
[Problems to be solved by the invention]
Since this type of conventional antenna system is configured and operates as described above, the following problems occur in the capturing operation.
As is well known, reception of radio waves on a mobile object has a significant change in reception level due to changes in the reception environment due to changes in location, traffic volume, and the like.
That is, for example, if the threshold of the reception level is raised to some extent in order to prevent noise from being captured, a phenomenon that cannot be captured despite the presence of a desired wave occurs in an environment where the reception level is low.
Further, if the threshold value is lowered and reception operation is performed with good reception sensitivity, side lobes and back lobes other than the main wave may be captured this time.
[0009]
Further, in the tracking operation, if the configuration is such that the small angle antenna is always rotated in order to detect the direction in which the intensity of the received radio wave is maximized, the intensity of the received radio wave always fluctuates.
In addition, when a side lobe or back lobe is captured, the captured side lobe or back lobe is always tracked.
Even if the main wave can be captured, if the angle at which the antenna is rotated during tracking is increased, the intensity of the received radio wave changes greatly, so that the rotation can be performed only at a very small angle, and therefore the electric field strength is included. It becomes very difficult to detect the antenna angle at which is maximized.
Furthermore, if the moving body equipped with the antenna system suddenly changes direction, the antenna is rotated to detect the electric field strength, and the center of rotation of the antenna is corrected to an angle that maximizes the reception level. During this time, the direction of the moving body changes greatly, so that there is a problem that an accurate peak angle of the electric field intensity cannot be detected and tracking cannot be performed.
[0010]
The present invention has been made to solve such a problem, and an object of the present invention is to provide an antenna system capable of accurately capturing and tracking a main wave of a desired wave and performing a stable reception operation.
[0012]
[Means for Solving the Problems]
The antenna system according to the present invention sets a reception frequency, captures the desired wave by facing the antenna against the desired wave based on the received electric field strength obtained by rotating the antenna in the azimuth direction, and captures the captured desired wave. In a tracking antenna system, a capture / tracking antenna control unit that constantly detects the direction of a desired wave by constantly rotating the capture / tracking antenna in the azimuth direction, and a desired wave detected by the capture / tracking antenna control unit. A receiving antenna control unit that constantly faces the receiving antenna in the direction of, and the capture / tracking antenna control unit for each direction obtained by rotating the capture / tracking antenna 360 degrees in the azimuth direction. the reception electric field level of the desired wave is measured, among the measured received electric field level, an intermediate value between the maximum reception electric field level and the second highest reception level threshold Constant and, by again rotating said acquisition and tracking antenna in the azimuth direction, and detects the position received the high reception electric field level than the threshold value as the direction of the desired wave. Accordingly, it is possible to capture and track radio waves from satellite devices mounted on a moving body and the like accurately and stably. Furthermore, in an antenna system that sets a reception frequency, captures a desired wave, and tracks the captured desired wave with the antenna facing the desired wave based on the received electric field strength obtained by rotating the antenna in the azimuth direction a reception electric field level measuring means for measuring reception field level of the desired wave for each direction obtained by rotating 360 degrees the antenna in the azimuth direction, among the received electric field level measured by the reception electric field level measuring means, the outermost An intermediate value between the large received electric field level and the second highest received level is set as a threshold, and the antenna is rotated again in the azimuth direction to stop the antenna at a position where a received electric field level higher than the threshold is received. And a desired wave capturing means for capturing the desired wave, and at the time of the tracking operation, the antenna beam is switched in two directions and the antenna beam is detected in the two directions. Arm, characterized in that has a respective signal level detecting you rotate the antenna in a direction in which the difference is always zero hope wave add tail means when swung. Accordingly, it is possible to accurately and stably capture and track radio waves from a satellite device or the like mounted on a moving body or the like.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment that is helpful in understanding the antenna system of the present invention. In FIG. 1, 10 is a control program that controls the operation of the entire system, 11 is a rotation control unit that controls the rotation of the antenna, 12 is an antenna rotation mechanism that rotates the antenna 360 degrees in the azimuth direction, and 13 receives radio waves from the satellite. 14 is a reception channel setting unit that selects a reception frequency and reception channel of a radio wave received by the antenna 13, 15 is a detection unit that detects a reception radio wave, 16 is an S level detection unit that detects reception level information, and 17 is A comparison circuit for comparing reception level information indicating the received electric field strength with a threshold value, 18 is a memory for storing reception level information output from the comparison circuit 17 exceeding the threshold value, and 19 is for setting a threshold value A threshold setting circuit to be changed.
[0014]
Reference numeral 20 denotes a micro-rotation control unit that rotates the antenna 13 around a predetermined angle by ± micro angle, 21 denotes an angle detection unit that detects the azimuth direction of the antenna 13 by angle, and 22 denotes the angle of the antenna 13 and the beam An angle / S level storage unit that stores reception level intensity corresponding to an angle, 23 is a peak angle detection unit that detects an antenna angle or beam angle at which the reception S level is maximum, and 24 is an antenna that oscillates the antenna beam by ± a minute angle. It is a beam switching unit.
[0015]
FIG. 2 is a flowchart showing the capturing operation of the antenna system shown in FIG.
When the acquisition operation is started, a desired reception channel is set in the reception channel setting unit 14 (step S21), and an initial threshold value M is set in the threshold setting circuit 19 (step S22). This initial threshold value M is set to a low threshold value on the assumption that the reception electric field level is low even if the reception environment is poor and a desired wave exists.
Then, under the control of the control program 10, the rotation control unit 11 operates the antenna rotating mechanism 12 to rotate the antenna once in the azimuth direction (step S23).
[0016]
The radio wave received from the antenna 13 is input to the reception channel setting unit 14, and the radio wave from the desired reception channel is detected by the detection unit 15, and the reception level detection unit 16 detects the received electric field strength and stores the information. Input to the comparison circuit 17.
The comparison circuit 17 compares the S level information indicating the received electric field strength with the threshold value M, and outputs the received S level exceeding the threshold value M to the memory 18 for storage.
Then, it is determined whether or not a desired wave exceeding the threshold value M has been detected when the antenna is rotated once (step S24). If no desired wave is detected, the process proceeds to step S25, where And the antenna 13 is rotated once again in the azimuth direction.
[0017]
As described above, the initial threshold value M is set to a low level so that the desired wave can be captured even when the reception environment is bad. Therefore, the main wave of the desired wave is stored in the memory 18 when step S24 is completed. In addition, side lobes and back lobes may be stored.
In the conventional antenna system, for example, when the side lobe is detected first, the rotation of the antenna is stopped at that time and the capturing operation is terminated.
[0018]
In the present invention, in consideration of the fact that the reception level of the main wave is always higher than that of the side lobes and back lobes, the highest level of the reception level stored in the memory 18 is detected in step S26, and a level value slightly lower than this level. Alternatively, an intermediate value between the maximum received electric field level and the second highest received level is set as a threshold value, the threshold value N is set in the threshold value setting circuit 19, and the antenna is rotated again in the azimuth direction ( Step S27).
And when the desired wave exceeding the newly set threshold value N is detected (step S28), it is set as the structure which stops rotation of an antenna at the angle, and complete | finishes acquisition operation | movement.
Therefore, when the desired wave exists, the main wave can be captured regardless of whether the reception level is low or high, and stable capture is possible.
[0019]
1 and 2 and the description thereof are embodiments that are helpful in understanding the antenna system of the present invention, and the antenna system shown in FIGS. 1 and 2 rotates the antenna 360 degrees in the azimuth direction. Received electric field level measuring means for measuring the received electric field level of the desired wave for each direction obtained, and a threshold value slightly lower than the maximum received electric field level among the received electric field levels measured by the received electric field level measuring means, or An intermediate value between the maximum received electric field level and the second highest received electric field level is set as a threshold value, the antenna is rotated again in the azimuth direction, and the received electric field level higher than the threshold value is received at the position. Any system provided with desired wave capturing means for stopping the antenna and capturing desired waves may be used.
[0020]
FIG. 3 is a block diagram showing a first embodiment of the antenna system of the present invention. 3, reference numeral 100 denotes an acquisition / tracking antenna control unit, reference numeral 200 denotes a reception antenna control unit, and the same reference numerals as those in FIG. 1 denote the same or corresponding parts. 1, in the implementation form described in FIG. 2, when there is a desired wave, that can capture this, even if the reception level is high or low wave, stable capture is becomes possible, the wave after capture Since the tracking operation is performed in the same manner as the conventional technique shown in FIG. 5, when the intensity of the received radio wave constantly fluctuates or the moving body suddenly changes its direction, the tracking cannot be performed. The point remains. Therefore, in the embodiment shown in FIG. 3, the capture / tracking antenna control unit 100 and the reception antenna control unit 200 are provided. The capture / tracking antenna control unit 100 always keeps the antenna 13a in the azimuth direction even after capturing the main wave. , The peak angle is always detected, and the azimuth angle of the receiving antenna 13b is synchronized with the detected peak angle.
[0021]
That is, as shown in the flowchart of FIG. 4, the capture / tracking antenna control unit 100 is operated to perform the same operations as steps S21 to S26 of FIG. 2 (step S41), and then the capture / tracking antenna 13a is turned on. When the desired wave exceeding the threshold value N is stored in the angle / S level storage unit 22 by rotating at a constant speed in the azimuth direction, the peak angle detection unit 23 detects the angle at that time (step S43). The rotation controller 11b operates the antenna rotating mechanism 12b so that the receiving antenna 13b faces the same azimuth angle as the peak angle detected once every time the capture / tracking antenna 13a rotates (step). S44).
Therefore, in the embodiment shown in FIGS. 3 and 4, the main wave of the desired wave can be captured regardless of the level of the desired wave, and the captured main wave can be stably tracked.
[0022]
3 and 4 and the description thereof are the first embodiment of the antenna system according to the present invention. The first antenna system according to the present invention always rotates the capture / tracking antenna in the azimuth direction so that the desired wave is transmitted. A capture / tracking antenna control unit that constantly detects the direction of the signal, and a reception antenna control unit that constantly faces the reception antenna in the direction of the desired wave detected by the capture / tracking antenna control unit. - tracking antenna control unit, said acquisition and tracking antenna measures the reception electric field level of the desired wave for each direction obtained by rotating 360 degrees in the azimuth direction among the measured received electric field level, maximum An intermediate value between the received electric field level and the second highest received electric field level is set as a threshold value, and the capture / tracking antenna is rotated again in the azimuth direction so that the received electric field level higher than the threshold value is obtained. The received position may be a system configured to detect a direction of a desired wave. FIG. 7 is a block diagram showing a second embodiment of the antenna system of the present invention. In FIG. 7, 24 is an antenna beam switching unit, 72 is a beam signal level (hereinafter referred to as beam S level) storage unit for storing the S level when the antenna beam is swung in two directions, and 73 is a capturing operation. S level detected in the middle, S level / beam S level detecting section for detecting the beam S level detected during the tracking operation, 74 is a beam signal for detecting the S level difference when the antenna beam is swung in two directions A difference detection unit 75 is a V / F converter that converts a level difference into a drive interval frequency. In the above-described embodiment described with reference to FIGS. 3 and 4, there are disadvantages in terms of the number of circuit parts and simplification of control because two antennas are required and the angle needs to be detected. Therefore, in the embodiment shown in FIG. 7, the level at the time of two antenna beams is always detected, and the tracking operation is performed by rotating the antenna in a direction in which the difference is always zero. That is, as shown in the flowchart of FIG. 8, the same operation as that of steps S21 to S26 of FIG. 2 is executed (step S81), and the antenna beam that is always required for the tracking operation control after the capturing operation is performed. The beam switching (phase shift switching) operation of the antenna 13 of the switching unit 24 is performed (step S82). The beam is used in only two directions, and it is swung at a constant interval at a minute angle with respect to the antenna facing direction, and the reception level is always detected at each beam position. When the level difference between two different beams is taken and it is always zero, the antenna 13 is facing the satellite. When the level difference has a value, the antenna 13 is tilted with respect to the satellite. In this case, the antenna rotation mechanism 12 is rotated in a direction in which the level difference becomes zero, and the antenna 13 is directly opposed to the satellite. The tracking operation is performed. The level difference value increases and the driving force increases as the level difference value determines the driving force of the rotating mechanism 12 and greatly changes from the satellite direction. Further, the drive interval of the rotating mechanism 12 is changed according to the change rate of the level difference value using the V / F converter 75, and the drive interval becomes narrower as the change rate is higher (such as a sudden turning of the moving body). The lower the rate of change, the wider the drive interval, and the faster and smoother the rotation of the tracking antenna is (step S83). Therefore, in the embodiment shown in FIGS. 7 and 8, the desired main wave can be captured regardless of the level of the desired wave, and the captured main wave can be stably tracked. Note 7, 8 and the description thereof is a second embodiment of an antenna system of the present invention, a second antenna system of the present invention, for each direction obtained by rotating 360 degrees the antenna in the azimuth direction a reception electric field level measuring means for measuring reception field level of the desired wave, of the received electric field level measured by the reception electric field level measuring means, an intermediate value between the maximum reception electric field level and the second highest reception field level A desired wave capturing means for setting a threshold value, rotating the antenna again in the azimuth direction, stopping the antenna at a position where a received electric field level higher than the threshold value is received, and capturing a desired wave; yet, antenna to detect the respective signal level direction in which the difference is always zero when the antenna beam in the two directions switching the antenna beam in two directions during the tracking operation has been swung The may be a system comprising a hope wave add tail means you rotate.
[0023]
【The invention's effect】
As described above, the antenna system of the present invention sets the frequency of the desired wave desired to be received, and once rotates the antenna once in all directions, a threshold value slightly lower than the strongest reception level, or the maximum An intermediate value between the received electric field level and the second highest received electric field level is set as a threshold value, and the capture operation is performed by rotating the antenna again, so even if the received level is low, the desired wave is received. It is possible to prevent the possibility of capturing side lobes and back lobes.
In addition, this operation is performed with the tracking antenna, and the peak angle is constantly detected while the tracking antenna is constantly rotated, and the angle of the receiving antenna is synchronized with the detected peak angle, so that the captured hope is obtained. Waves can be tracked stably.
Furthermore, during the tracking operation, the antenna beam is switched in two directions, each S level when the antenna beam is shaken in the two directions is detected, and the antenna is rotated in a direction in which the difference is always zero. It has a feature that makes the rotation of the antenna to be tracked faster and smoother by changing the rotation drive interval according to the rate of change of the level difference, enabling stable tracking of the captured desired wave and capturing operation. In addition, the tracking operation has an effect that an angle detection is not required.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment for reference in understanding an antenna system of the present invention.
FIG. 2 is a flowchart for explaining a capturing operation in the antenna system shown in FIG. 1;
FIG. 3 is a block diagram showing a first embodiment of the antenna system of the present invention.
4 is a flowchart for explaining a tracking operation in the antenna system shown in FIG. 3;
FIG. 5 is a block diagram showing an example of this type of conventional antenna system.
6 is a flowchart for explaining a capturing operation in the antenna system shown in FIG.
FIG. 7 is a block diagram showing a second embodiment of the antenna system of the present invention.
8 is a flowchart for explaining a tracking operation in the antenna system shown in FIG.
[Explanation of symbols]
10 control program 11, 11a, 11b rotation control unit 12, 12a, 12b antenna rotation mechanism 13, 13a, 13b antenna 14, 14a, 14b reception channel setting unit 15 detection unit 16 S level detection unit 17 comparison circuit 18 memory 19 threshold Value setting circuit 20 Micro rotation control unit 21 Angle detection unit 22 Angle / S level storage unit 23 Peak angle detection unit 24 Antenna beam switching unit 72 Beam S level storage unit 73 S level / beam S level detection unit 74 Beam S level difference Detection unit 75 V / F converter 100 Capture / tracking antenna control unit 200 Reception antenna control unit

Claims (2)

In an antenna system that sets a reception frequency, captures a desired wave by facing the antenna against a desired wave with reference to a received electric field strength obtained by rotating the antenna in the azimuth direction, and tracks the captured desired wave,
A capture / tracking antenna control unit that constantly rotates the capture / tracking antenna in the azimuth direction to constantly detect the direction of the desired wave;
A receiving antenna control unit that constantly faces the receiving antenna in the direction of the desired wave detected by the acquisition / tracking antenna control unit,
The capture / tracking antenna control unit measures a received electric field level of a desired wave in each direction obtained by rotating the capture / tracking antenna 360 degrees in an azimuth direction, and among the measured received electric field levels , an intermediate value between the maximum reception electric field level and the second highest reception level is set to the threshold, the capture and track antenna is rotated in azimuth direction, receive a high reception electric field level than the threshold value again An antenna system characterized in that the detected position is detected as a desired wave direction. In the antenna system for setting the reception frequency and capturing the desired wave by facing the desired wave with respect to the received electric field strength obtained by rotating the antenna in the azimuth direction,
A received electric field level measuring means for measuring a received electric field level of a desired wave in each direction obtained by rotating the antenna 360 degrees in the azimuth direction;
Among the received electric field level received field level measured by the measuring means, an intermediate value between the maximum reception electric field level and the second highest reception level is set to the threshold, then again rotating the antenna in the azimuth direction, A desired wave capturing means for capturing the desired wave by stopping the antenna at a position where a received electric field level higher than the threshold is received;
Yet, the tracking during the operation, switching the antenna beam in two directions, the two directions in the antenna beam hope you rotate the antenna and the difference detecting the respective signal level is always a direction to become zero when swung antenna system characterized by comprising a wave add tail unit.

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