JP3920151B2 - In-vehicle antenna device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle-mounted antenna device that controls the rotation of an antenna so that radio waves from a satellite can be always received with the highest sensitivity.
[0002]
[Prior art]
A conventional vehicle-mounted antenna device will be described with reference to FIG. The disk-shaped antenna 21 has an elevation angle with respect to the satellite and a specific directivity, and is rotationally controlled by a motor 22. The antenna 21 receives radio waves (approximately 11 to 13 GHz) from the satellite and inputs them to the low noise converter 23. The low noise converter 23 converts the frequency of the input radio wave to 1 to 2 GHz and inputs it to the distributor 24. One output of the distributor 24 is input to the BS tuner 25, and the other output is input to the reception intensity detection means 26 a of the rotation control unit 26. The reception intensity detection means 26a detects the reception intensity of the radio wave, converts it into an analog voltage or a digital signal corresponding thereto, and inputs it to the level determination means 26b.
[0003]
For example, two thresholds having different levels are set in the level determination unit 26b, and the detected reception intensity is compared with the threshold. Then, in the first level region where the reception intensity is higher than the higher threshold, or in the second level region between the two thresholds, or in the third level region below the lower threshold It is determined whether there is any.
[0004]
The radio wave reception strength varies depending on the antenna directivity and the direction of the antenna relative to the satellite, and the reception strength decreases as the main lobe of the directivity shifts from the antenna direction. That is, the lobe direction and the antenna direction substantially coincide.
Then, the level determination unit 26b outputs a determination result corresponding to the reception intensity to the rotation speed control unit 26c.
[0005]
The rotational speed control means 26c outputs a rotational speed signal for setting the rotational speed of the antenna to the motor driver 26d corresponding to each determined level region. That is, if the determination result is the first level region, a rotation speed signal for rotating the motor 22 at the slowest speed is output, and if the determination result is the second level, rotation for rotating the motor 22 at an intermediate speed. A speed signal is output, and if it is the third level, a rotation speed signal for rotating the motor 22 at the fastest speed is output. The motor driver 26d rotates the motor 22 by the input rotation speed signal.
[0006]
Therefore, the rotation speed of the antenna 21 is controlled to be faster as the reception intensity is lower and to be slower as the reception intensity is higher. By this rotation control method, the antenna 21 is rotated to an angle at which the reception intensity increases in a short time, and thereafter, the speed is decreased and the antenna 21 is controlled so as to be directed in a direction in which the reception intensity is maximized accurately.
[0007]
[Problems to be solved by the invention]
However, when the received intensity changes above and below the threshold, the determined level region changes each time, so the rotation speed of the antenna also changes. Therefore, the rotation operation is not smooth and unstable. Also, since the reception strength is affected by the weather, etc., the reception strength also changes accordingly, so that the captured radio waves are not easily missed, and when the reception strength increases from the lower one, it is easily It is necessary to prevent the lobe signal from being captured.
[0008]
Accordingly, an object of the present invention is to stabilize the rotation by avoiding frequent changes in the rotation speed of the antenna as the reception intensity changes, and to improve satellite tracking performance.
[0009]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the present invention comprises an antenna and a rotation control unit that controls the rotation of the antenna so that the direction of the antenna is directed toward the satellite. The rotation control unit includes the antenna. Reception intensity detection means for detecting the reception intensity of the received radio wave at predetermined time intervals, level determination means for determining which of the level areas into which the detected reception intensity is divided, and A rotation speed control means for setting the rotation speed of the antenna corresponding to a level region, and the level determination means includes an upper threshold value that is a predetermined level higher than a reference threshold value to be compared with the reception intensity. A lower threshold value is set lower than a predetermined level. When the reception strength is increasing, the reception strength is compared with the upper threshold value. When the reception strength is decreasing, the reception strength is compared. And to compare with the lower threshold value.
[0010]
Further, the upper threshold and the lower threshold are set with respect to the reference threshold having the highest level among the reference thresholds.
[0011]
In addition, the rotation speed is decreased as the level region of the reception intensity is higher.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The vehicle-mounted antenna device of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of an in-vehicle antenna device, FIG. 2 is a reception strength characteristic diagram of the antenna, FIG. 3 is a flowchart for explaining a determination procedure when determining a level region of reception strength, and FIG. It is a figure which shows the level determination at the time.
[0013]
First, in FIG. 1, the disk-shaped antenna 1 has an elevation angle with respect to the satellite and a directivity characteristic, and is rotated by a motor 2. The antenna 1 receives radio waves (approximately 11 to 13 GHz) from the satellite and inputs them to the low noise converter 3. FIG. 2 shows the received intensity when the antenna is rotated to receive the radio wave from the satellite, and this characteristic is determined by the directivity characteristic of the antenna. The central area M is due to the main lobe of directional characteristics, and the areas S1 and S2 on both sides thereof are due to the side lobe.
[0014]
The low noise converter 3 converts the frequency of the input radio wave to 1 to 2 GHz and inputs the frequency to the distributor 4. One output of the distributor 4 is input to the BS tuner 5, and the other output is input to the reception intensity detection means 6 a of the rotation control unit 6. The reception intensity detection means 6a detects the reception intensity of the radio wave, converts it to an analog voltage or a digital signal corresponding thereto, and inputs it to the level determination means 6b.
[0015]
The level determination means 6b is constituted by a microcomputer, and includes a predetermined reference value above and below each of two virtual reference threshold values (first reference threshold value R1, second reference threshold value R2, and R1> R2). Upper threshold values R1U and R2U and lower threshold values R1L and R2L having different levels are set by a program. The upper threshold values R1U and R2U and the lower threshold values R1L and R2L are actual threshold values for comparison with the reception strength. Then, the upper threshold value R1U and the lower threshold value R1L corresponding to the first reference threshold value R1 are set within the range of the reception intensity of the region M by the main lobe, and the upper threshold value R2U corresponding to the second reference threshold value R2 and the lower threshold value R1U are set. The side threshold value R2L is set within the range of the reception intensity of the area S1 due to the side lobe.
[0016]
In the level determination means 6b, the detected reception intensity is compared with the upper threshold values R1U and R2U and the lower threshold values R1L and R2L, and roughly in the first level region (L1) equal to or higher than the first reference threshold value R1. Or a second level region (L2) that is between the first reference threshold R1 and the second reference threshold R2, or a third level region (L3) that is less than or equal to the second reference threshold R2. It is determined whether there is any. And the determination result corresponding to each level is input into the rotational speed control means 6c.
[0017]
The rotation speed control means 6c outputs a rotation speed signal corresponding to the determination result. That is, if the determination result is the first level region L1, a rotation speed signal for rotating the motor 2 at the slowest speed is output, and if the determination result is the second level region L2, the motor 2 is rotated at an intermediate speed. A rotation speed signal for rotating the motor 2 at the fastest speed is output in the third level region L3. The rotation speed signal is input to the motor driver 6d, and the motor 2 rotates at the rotation speed.
[0018]
Next, a comparison operation between the reception strength by the level determination means 6b and the upper threshold values R1U and R2U and the lower threshold values R1L and R2L will be described with reference to FIGS. In order to simplify the explanation, it is assumed that the upper threshold R2U and the lower threshold R2L corresponding to the second reference threshold R2 are not set, and correspond to the second reference threshold R2 and the first reference threshold R1. It is assumed that an upper threshold value R1U and a lower threshold value R1L are set. When the second reference threshold value R2 is close to the noise level, it is not necessary to set the upper threshold value R2U and the lower threshold value R2L.
[0019]
In FIG. 3, first, when the detected reception strength (E) is input to the level determination means 6b in step (S1), it is compared in step (S2) whether the reception strength is higher than the second reference threshold value R2. The Here, if E <R2, it is determined that the reception intensity is in the third level region L3. If E> R2, the process proceeds to step (S3), and it is determined whether the reception intensity is increasing from the change state between the reception intensity detected last time and the reception intensity detected this time. Here, if it is rising, it will progress to step (S4) and it will be compared whether it is higher than upper threshold value R1U corresponding to 1st reference threshold value R1.
[0020]
If it is rising and E> R1U, it is determined that the reception intensity is in the first level region L1. If E <R1U, it is determined that the reception intensity is in the second level region L2. That is, when the reception intensity is increasing, it is compared with the upper threshold value R1U to determine whether it is the first level region L1 or the second level region L2. The state of determination in the above step (4) is the UP area in FIG.
[0021]
On the other hand, if the reception strength is decreasing in step (S3), the process proceeds to step (S5) to compare whether the reception strength is higher than the lower threshold R1L. If E> R1L, it is determined that the received intensity is in the first level region L1, and if E <R1L, it is determined that it is in the second level region L2. That is, when the reception intensity is decreasing, it is compared with the lower threshold value R1L to determine whether it is the first level region L1 or the second level region L2. The state of determination in the above step (5) is the DOUN area of FIG.
[0022]
Therefore, even when the reception strength changes between the upper threshold value R1U and the lower threshold value R1L, it is not compared with the intermediate reference threshold value R1, so that the determined level region does not change frequently and the antenna is stable. Then rotate. The rotation speed of the antenna 1 is controlled so that the lower the reception intensity level region is, the higher the speed is, and the higher the speed is, the slower the antenna 1 is. It is controlled to face the direction. When the maximum reception intensity is reached, the rotation of the antenna 1 stops and the BS tuner 5 receives the radio wave of the satellite signal.
[0023]
【The invention's effect】
As described above, in the present invention, the rotation control unit includes reception intensity detection means for detecting the reception intensity of the radio wave received by the antenna at predetermined time intervals, and the detected reception intensity is divided into a plurality of levels. A level determination means for determining which of the areas corresponds, and a rotation speed control means for setting the rotation speed of the antenna corresponding to the level area, and the level determination means has a reference threshold value to be compared with the reception intensity. On the other hand, an upper threshold value that is higher by a predetermined level and a lower threshold value that is lower than a predetermined level are set. When the reception strength is increasing, the reception strength is compared with the upper threshold value, and when the reception strength is decreasing. Since the received intensity is compared with the lower threshold, even if the received intensity changes between the upper threshold and the lower threshold, it is not compared with the intermediate reference threshold between them. frequent Without having to change the antenna to rotate stably.
[0024]
Further, since the upper threshold and the lower threshold are set with respect to the reference threshold having the highest level among the reference thresholds, the determination of the level region is accelerated when the reference threshold having a low level is close to the noise level.
[0025]
Further, since the rotation speed is slowed as the reception intensity level region is higher, the rotation of the antenna is controlled so as to be directed in a direction where the reception intensity is maximized in a short time.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an in-vehicle antenna device of the present invention.
FIG. 2 is a graph showing the reception strength characteristics of the antenna in the in-vehicle antenna device of the present invention.
FIG. 3 is a flowchart showing a procedure for determining the level of received intensity in the in-vehicle antenna device of the present invention.
FIG. 4 is a diagram showing a state of level determination with respect to a change in reception intensity in the in-vehicle antenna device of the present invention.
FIG. 5 is a configuration diagram of a conventional in-vehicle antenna device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Antenna 2 Motor 3 Low noise converter 4 Divider 5 BS tuner 6 Rotation control part 6a Reception intensity detection means 6b Level determination means 6c Rotation speed control means 6d Motor driver

Claims (3)

An antenna, and a rotation control unit that controls the rotation of the antenna so that the direction of the antenna is directed to the direction of the satellite, and the rotation control unit sets the reception intensity of the radio wave received by the antenna at predetermined time intervals. Receiving intensity detecting means for detecting the level, means for determining whether the detected receiving intensity falls into a plurality of level areas, and a rotation speed of the antenna corresponding to the level area. A rotational speed control means for setting, and the level determination means sets an upper threshold value that is higher by a predetermined level and a lower threshold value that is lower than a predetermined level relative to a reference threshold value to be compared with the received intensity, The reception strength is compared with the upper threshold value when the reception strength is increasing, and the reception strength is compared with the lower threshold value when the reception strength is decreasing. A vehicle-mounted antenna device according to. The in-vehicle antenna device according to claim 1, wherein the upper threshold and the lower threshold are set with respect to a reference threshold having the highest level among the reference thresholds. The in-vehicle antenna device according to claim 1, wherein the rotation speed is decreased as the level region of the reception intensity is higher.

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