JPH04339213A - Antenna tracking system - Google Patents

Abstract

PURPOSE:To enable a highly directional antenna to track a broadcasting station accurately by calculating the direction of a transmitting position from the position of a moving object detected, information on direction and stored information on the transmitting position to drive the antenna in the direction of the transmitting position. CONSTITUTION:The present position P1 of a vehicle is determined with a map matching processing section 13 based on running range and geomagnetic sensors 10 and 11 and a map data file 12 and displayed 23 through a monitor display processing section 24. Angle of rotation of an antenna is calculated based on the position P1, the direction of the vehicle determined with the sensor 11 and the position P2 of a broadcasting station registered in a broadcasting station location file 14 and an antenna rotary base 16 is driven through a motor drive control section 18. The angle of rotation detected with an angle of rotation detecting section 17 is fed back to the control section 18. A high frequency signal from the antenna of the rotary base 16 is converted into a video signal with a video processing section 19. An signal screen memory section 20 compares an average level of the video signal and a mean of the video signal per screen and the results are outputted to a TV display 25.

Description

[Detailed description of the invention]

0001

[Purpose of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna tracking system for tracking an antenna mounted on a moving body such as a vehicle in a transmission direction.

0003

2. Description of the Related Art Recently, as televisions have become smaller, lighter, and consume less power, more and more televisions are being mounted on vehicles. When a television is mounted in a car in this way, unlike when watching television at home, the positional relationship between the broadcast station and the television changes. Furthermore, when watching television in high definition, an antenna with a certain degree of directivity is also required to prevent ghosting and the like.

FIG. 3 is a diagram showing an example of a conventional diversity antenna installed in a car, and FIG. 4 is a block diagram showing an example of the configuration of an in-vehicle television system.

As shown in these figures, antennas 1, 2, 3, and 4 are provided at the front, rear, left, and right sides of a vehicle C, respectively. Each of these antennas 1, 2, 3, and 4 has a certain degree of directivity in its direction, and together these antennas can cover a range of 360 degrees.

High frequency signals from these four antennas are input to a high frequency switching circuit 5. On the other hand, TV receiver 6
Vertical synchronization pulses and horizontal synchronization pulses are input to the timing control circuit 7. The level detection comparison circuit 8 constantly compares the video signals of the television receiver 6, and based on the timing output from the timing control circuit 7, selects the antenna whose video signal has reached the maximum level within the vertical synchronization feedback of the television screen. High frequency switching circuit 5 to select when receiving one screen
Outputs a switching signal to.

By the way, in such a diversity antenna system, if the direct waves from the broadcasting station are weakened by obstacles on the way, and conversely there are many ghosts mixed with strong reflected waves from buildings etc., the directivity of the antenna will be affected. Since it is not high, the TV screen while driving is constantly switching between the regular TV screen and the ghost screen, making it appear as if the screen is shaking horizontally. In addition, switching the receiving antenna caused a screen skipping phenomenon, resulting in a problem of deterioration of image quality.

On the other hand, when a highly directional antenna is installed, either the antenna is constantly swung from side to side to move the center of the sway displacement, or the antenna's directional characteristics are electrically changed to move it in the direction of higher reception level. The direction of the broadcasting station is detected by moving the entire antenna. However, if this is done, the problem arises that the antenna cannot be oriented accurately because the strength of the radio waves always changes greatly due to the movement of the vehicle body, such as changes in obstacles on the way or ghosts.

[0009]

As described above, when a diversity antenna is used in a conventional in-vehicle television, the directivity is relatively low, resulting in deterioration of image quality due to effects such as ghosting. In addition, when detecting a direction with a high reception level and moving a highly directional antenna toward the broadcast station, the strength of the radio waves will always change greatly due to the movement of the vehicle, such as changes in obstacles on the way or ghosts. Therefore, a problem arose in that it was not possible to accurately orient the antenna.

The present invention was devised to solve the above-mentioned problems, and an object of the present invention is to provide an antenna tracking system that can accurately track a broadcasting station by a highly directional antenna mounted on a vehicle.

[0011]

[Structure of the invention]

0012

[Means for Solving the Problems] In order to achieve the above object, the antenna tracking system of the present invention includes a directional antenna provided on a moving object, and a moving object position detector for detecting the position of the moving object. means, a moving body direction detecting means for detecting the direction of the moving body, a transmitting position information storage means storing information on a transmitting position from which a signal to be received is transmitted, and a mobile body position detecting means. The direction of the transmission position as seen from the mobile body is determined from the detected position information of the mobile body, the direction information detected by the mobile body direction detection means, and the signal transmission position information stored in the transmission position information storage means. a transmission position direction calculation means for calculating;
Antenna driving means is provided for driving the antenna so as to point in the direction of the transmission position determined by the transmission position direction calculation means.

[0013]

[Operation] In the antenna tracking system of the present invention, the moving object position information detected by the moving object position detecting means, the moving object direction information detected by the moving object direction detecting means, and the transmission position stored in the transmission position information storage means The direction of the transmission position is calculated from the information by the transmission position direction calculation means. Then, the antenna is driven by the antenna driving means so as to face in the direction of this transmission position.

[0014] Therefore, it becomes possible to accurately direct the directional antenna to the transmission position.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the antenna tracking system of the present invention.

In the figure, 10 is a mileage sensor that detects the distance traveled by the car, 11 is a geomagnetic sensor that detects the direction of the car, 12 is a map data file storing map data, and 13 is a mileage sensor. 10, the geomagnetic sensor 11, and the map data file 12.
A map matching processing unit that calculates 1 (X1, Y1), 1
Reference numeral 4 denotes a broadcast station location file in which data on the location of the broadcast station is stored; 15 indicates an antenna direction calculation unit that determines the direction of the antenna based on the geomagnetic sensor 11, the map matching processing unit 13, and the broadcast station location file 14; 16
17 is a rotation angle detection unit that detects the rotation angle of the antenna; 18 is a motor that controls the rotation of the antenna rotation unit 16 from the antenna direction calculation unit 15 and the rotation angle detection unit 17; a drive control unit; 19, a video processing unit that performs video processing from a high-frequency signal from an antenna provided on the antenna rotating table 16; 20, a one-screen memory unit that holds image data for one screen of the video processing unit 19; 2 is a timing control circuit that generates the timing of one vertical synchronization from the video signal of the video processing unit 19; 22 is a level detection comparison unit that detects and compares the level of the video signal of the video processing unit 19; and 23 is a display unit that displays map information. monitor, 24
is a monitor display processing section that controls the monitor 23;

Next, the operation of the antenna tracking system configured as described above will be explained.

First, the current position P1 (X1, Y1) of the vehicle is determined by the map matching processing section 13 based on the mileage sensor 10, the geomagnetic sensor 11, and the map data file 12. On the other hand, the position P2 (X2, Y2) of the broadcasting station is registered in advance in the broadcasting station location file 14. Then, the antenna direction calculation unit 15 calculates the current position P1 (X1, Y1
), the direction of the vehicle determined by the geomagnetic sensor 11, and the information stored in the broadcast station location file 14, the rotation angle of the antenna is calculated. This rotation angle is sent to a motor drive control section 18, which drives an antenna rotating table 16 installed on the upper part of the vehicle body. Further, the rotation angle detection section 17 detects the rotation angle and feeds it back to the motor drive control section 18 to cause the antenna to follow the rotation angle with high precision and high speed.

The current position P1 (X1, Y1) and the map are subjected to monitor display processing by the monitor display processing section 24 and displayed on the monitor 23.

A high frequency signal from an antenna provided on the antenna rotating table 16 is sent to a video processing section 19 of the in-vehicle television and converted into a video signal. This video signal is sent to a one-screen memory section 20 and a level detection/comparison section 22. The one-screen memory section 20 A/D converts the video signal and stores it in memory. The level detection and comparison section 22 compares the average level of the video signal with the average value of the video signal of the next one screen (field). Since the comparison timing must be performed within vertical feedback, synchronization is achieved with the output signal from the timing control circuit 21, and the result is sent to the one-screen memory section 20. In other words, if the video signal level of the next screen is below a certain value, it is determined that the reception condition is extremely poor due to radio wave interference, and the video data of the previous screen is D/A converted and the TV display 2
Send to 5. When the video signal level of the next screen is higher than a certain value, the information of the video signal of the next screen is overwritten on the video information of the previous screen in the one-screen memory section 20. The video signal is then output to the television display 25.

When the S/N is better than a predetermined S/N, the audio signal is output continuously, amplified by the low frequency amplifying section 26, and then output from the speaker 27. However, if a sufficient S/N ratio cannot be obtained, muting is applied to prevent the audio signal from being output. Next, antenna direction calculation section 1
The operation of calculating the direction in No. 5 will be explained.

FIG. 2 shows an X-
FIG. 3 is a diagram showing a plane of a Y coordinate system.

[0024] The current vehicle position is P1 (X1, Y1),
Let the position of the broadcasting station be P2 (X2, Y2). At this time,
It will be shown below that the orientation angle θ of the antenna can be determined from P1 (X1, Y1), P2 (X2, Y2), and the angle α between the N pole and the direction of travel of the vehicle.

When a straight line L connecting the vehicle and the broadcasting station is drawn, and if the angle between this straight line L and the north pole direction is β, then the equation shown in Equation 1 holds true.

[0026]

[Math 1]

When β is eliminated from these equations, the equation shown in Equation 2 is established.

[0028]

[Math 2]

By the way, the position P1 (X1, Y1) of the vehicle
And the angle α between the north pole and the direction of travel of the car is determined by the mileage sensor 10, the geomagnetic sensor 11, the map data file 12,
It is determined by the map matching processing section 13. Further, the position P2 (X2, Y2) of the broadcasting station is obtained from the broadcasting station location file 14. Therefore, the orientation angle θ of the antenna is determined. Furthermore, when the vehicle moves to position P3, the angle θ can be calculated in the same manner.

Therefore, in the antenna tracking system of this embodiment, it is possible to accurately track the highly directional antenna in the direction of the broadcasting station. Therefore, it is possible to reduce ghosts and display high-quality images. and 1
By having the screen memory section 20, sudden S/S due to radio wave interference etc.
When N decreases, the previous screen data is displayed as a still image, making the screen easier to see.

Furthermore, in the embodiment described above, the position P of the broadcasting station
2 (X2, Y2) is stored in the broadcast station location file 14, but it is also possible to read it from the map data file 12.

Furthermore, it is possible to correspond not only to terrestrial broadcasting stations but also to satellite broadcasting by setting three-dimensional coordinate axes.

[0033]

According to the antenna tracking system of the present invention, the moving object position information detected by the moving object position detecting means, the moving object direction information detected by the moving object direction detecting means, and the moving object direction information detected by the moving object direction detecting means are stored in the transmission position information storage means. The direction of the transmission position is calculated by the transmission position direction calculation means from the transmission position information. Then, the antenna is driven by the antenna driving means so as to face in the direction of this transmission position. This makes it possible to accurately direct an antenna with high directivity to the transmission position.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an antenna tracking system of the present invention.

FIG. 2 is a diagram showing a plane of an X-Y coordinate system in which the N-pole direction is the positive direction of the Y-axis, for explaining the direction calculation operation of the antenna direction calculation unit.

FIG. 3 is a diagram showing an example of a conventional diversity antenna installed in a car.

FIG. 4 is a block diagram showing an example of the configuration of a conventional in-vehicle television system.

[Explanation of symbols]

10... Mileage sensor 11...Geomagnetic sensor 12...Map data file 13...Map matching processing section 14...Broadcast station location file 15...Antenna direction calculation unit 16...Antenna rotation stand 18...Motor drive control section

Claims (1)

[Claims] 1. A directional antenna provided on a moving object, a moving object position detecting means for detecting the position of the moving object, a moving object direction detecting means for detecting the direction of the moving object, and a receiving device. a transmitting position information storage means storing information on a transmitting position that is transmitting a signal to be transmitted; a transmitting position information storing means storing information on a transmitting position at which a signal is transmitted; a position information of the moving body detected by the moving body position detecting means; a transmitting position direction calculating means for calculating the direction of the transmitting position as seen from the moving object from the direction information and the signal transmitting position information stored in the transmitting position information storage means; An antenna tracking system comprising: antenna driving means for driving the antenna so as to direct the antenna in the direction of the transmission position.