JPH08250921A - On-vehicle satellite broadcast receiver - Google Patents

Abstract

PURPOSE: To reduce cost by simplifying the configuration of an on-vehicle satellite broadcast receiver having provision for a broad frequency band with two antennas whose elevation angles differ from each other. CONSTITUTION: A mixed signal being an output of a mixer section 1 mixing outputs of antennas A, B whose elevation angles differ from each other is fed to the front end 2, in which the signal is demodulated. A C/N detection section 5 detects a C/N from an 8MHz band signal extracted from a demodulation output signal and outputs it to a control section 6 comprising a microcomputer, which controls the antenna in the direction such that the C/N level of an antenna at an optimum level is the maximum at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite broadcast receiver such as BS and CS, and more particularly to a satellite broadcast receiver suitable for vehicles such as vehicles.

[0002]

2. Description of the Related Art Generally, a parabola or a plane antenna for receiving satellite broadcasts such as BS and CS has a plane direction azimuth and a vertical direction elevation angle in order to increase the efficiency of the antenna. Need to turn to. Therefore, even when the purpose is to mount a mobile unit and receive BS / CS, it is necessary to change and track the azimuth angle and the elevation angle according to the moving location. However, if the azimuth and elevation are variable, the structure becomes complicated and BS / C
The outer diameter dimension of the S antenna itself, particularly the dimension in the height direction, increases, and it can be installed only in a large vehicle such as a bus.

Therefore, a method of limiting the use area and fixing the elevation angle is considered, and even if the elevation angle is fixed, the directivity in the elevation angle direction and the practical range of the angle are usually about ± 4 ° to ± 8 °. Since there is a width, it is possible to receive in a width of about 8 ° to 16 ° north and south of the Japanese archipelago. This value is 1/3 of the north and south of the Japanese archipelago
It can cover an area of ~ 1/2.

However, some users may move beyond this range, and this is not a means to satisfy all users. Therefore, two plane antennas with different elevation angles are mounted on the vehicle for use. It is also considered to do. FIG. 4 is a schematic block diagram of an example thereof.

In the figure, antennas A and B are two plane antennas mounted on a vehicle and having different elevation angles, and receive BS / CS and output high-frequency signals as BS-IF. Reference numerals 31A and 31B are front end (FE) blocks for amplifying and demodulating the output signals from the both antennas.
CN detection unit 32A through a BPF of Hz (not shown),
32B respectively. CN ratio detection unit 32A, 3
2B receives the signal and detects the CN ratio of the received signal. Since the CN ratio value is an analog value, AD
AD conversion is performed by the conversion units 33A and 33B, and both are input to the control microcomputer 34.

On the other hand, 35A and 35B are video processing circuits, which process the video signal portions in the signals output from the front ends 31A and 31B and demodulate them to baseband. 36
Is a video switching unit, and the video processing circuits 35A, 3A
The output of 5B is selected by the control of the microcomputer 34, and either one is output. Therefore, by selecting the antenna output with the higher CN ratio value from the two inputs to the control microcomputer 34 by the video switching unit 36, the optimum antenna is selected and the reception state is good. can do. It should be noted that both antennas are provided with motor control circuits 3 so that the CN ratio has a peak value.
It has a function of rotating an azimuth angle by a motor (not shown) by 7A and 37B. As for the audio circuit, the front end 31A. Although demodulated from 31B through the audio signal processing circuit, the description is omitted.

[0007]

By using the device having the above-mentioned structure, it is possible to meet the demand of the user who moves in a wide range. However, as described above, this device including the antenna is completely The system is composed of two systems, which causes a big problem in terms of cost. The present invention seeks to satisfy this requirement at a lower cost.

[0008]

SUMMARY OF THE INVENTION According to the present invention, the above object is to adjust and fix the elevation angle so as to be different from each other and to provide two antennas each having an azimuth angle rotating means, and to receive the both antennas. A mixing unit for mixing signal outputs; a front end for amplifying and demodulating an output signal of the mixing unit; a CN ratio detecting unit for detecting a CN ratio of a received signal from an output of the front end; and a CN ratio detecting unit. A vehicle-mounted satellite broadcast receiver, comprising: a control unit that controls and drives the azimuth angle rotation means of the antenna according to the output to change the azimuth angle so that the value of the CN ratio reaches a peak. be able to.

In the preceding paragraph, the two antennas cover a wide area by adjusting and fixing the elevation angles respectively suitable for the two areas adjacent to the north and south, so that the intended purpose can be achieved.

Furthermore, in the preceding paragraph or the preceding two paragraphs, the two antennas have the same directivity direction,
Further, the problem can be solved by making the rotation angular velocity and the rotation direction the same.

Further, in the preceding two items or the preceding second item, the two antennas have their directivity directions different from each other, while the rotational angular velocity and the rotational direction are the same, thereby solving the problem. be able to.

[0012]

After the received signals of the two antennas are mixed by the mixing section to form one, the CN ratio is detected from the signals amplified and demodulated in the front end, and the control section controls the azimuth angle of the antenna. The circuit configuration after the front end can be limited to one system.

Further, the elevation angles of the two antennas are adjusted and fixed to the elevation angles suitable for the two areas adjacent to the north and south, and the reception signals of the two antennas are mixed by the mixing section to be one, The control unit controls the azimuth angle of the antenna by detecting the CN ratio from the signal that is amplified and demodulated at the end, so the circuit configuration after the front end is only one system and covers a wide area. Becomes

Even if the two antennas have the same directivity center direction or different directivity center directions, the control unit controls the CN by setting the same rotation angular velocity and rotation direction. The ratio can be detected to control the azimuth of the antenna.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention achieves the above-mentioned object by using two BS / CS plane antennas having different elevation angles and having one system from the front end onward. FIG. 1 is a block diagram of the same. Antennas A and B are two BS / CS planar antennas having different elevation angles, and antenna control circuits 7A and 7B are provided respectively.
Has a function of rotating the azimuth angle by driving a motor (not shown). 1 is the antenna A,
This is a mixing unit that mixes the output signals of the antenna B. Reference numeral 2 is a front end (FE) that amplifies and demodulates the output signal of the mixing unit 1. 5 is the output of the front end 2
A CN ratio detector input through a BPF of MHz, and 6 is a control unit by a microcomputer, which outputs a control signal to the antenna control circuits 7A and 7B according to the output of the CN ratio detector 5. Reference numeral 3 denotes a video processing unit that processes a video signal portion in the output signal from the output of the front end 2 and demodulates it to a baseband. Reference numeral 4 similarly processes an audio signal portion in the output signal from the output of the front end 2 and bases it. An audio processing unit that demodulates to a band.

In the apparatus of the present invention having such a structure,
For example, the antenna A is for East Japan and the antenna B is for West Japan. When the antennas are installed so that the directivity directions thereof are the same, the antennas are rotated at the same angular velocity, and the satellite broadcast is received at a certain point, the two antennas have different elevation angles.
As shown in the graph, there is a difference in the change of both CN ratio values with respect to the rotation angle, and in the example of the figure, the antenna A has a larger CN ratio level than the antenna B. Depending on the receiving location, there may be a level change only in the antenna A or only in the antenna B, but in any case, it is possible to determine the magnitude of the CN ratio level. Therefore, the antenna is rotated by the antenna control circuit 7A or 7B in such a direction that the CN ratio level of the antenna of the optimum level of the two always has a peak. In the present embodiment, the antenna A is rotated by the antenna control circuit 7A and is controlled so as to face the direction in which the CN ratio reaches its peak.

On the other hand, even for video and audio signals, if the tracking is always satisfied by one of the antennas,
The signal can be demodulated at the front end.

In the above description, the directivity directions of the two plane antennas are set to the same direction, and the two plane antennas are rotated at the same angular velocity. However, the two plane antennas are set to have different directivity directions. However, reception is possible. The graph shown in FIG. 3 shows changes in the CN ratio values of the antenna A and the antenna B with respect to the rotation angle when the center azimuth angles are mutually displaced as described above. In this example, the antenna A has a CN ratio value. Since the level is good, the control unit 6 causes the antenna control circuit 7A to rotate the antenna so that the CN ratio level of the antenna A is maximized. In this case, C
If the N ratio level is continuous, it is possible to detect the peak value.

Further, in actual commercialization, since it is necessary to constantly detect the rotation direction due to changes in the running of the vehicle, a means such as a vibration gyro may be used together. Further, when the vibrating gyro is not used by the simple method, it is necessary to once forcibly rotate in either direction to determine the direction of the vehicle.

[0020]

As described above, according to the present invention, since the front end of the vehicle-mounted satellite broadcasting receiver having two plane antennas for coping with a wide area is constituted by one system, the conventional system is completely completed. It is expected that the cost will be significantly reduced compared to the device that was composed of two systems.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an embodiment of a vehicle-mounted satellite broadcast receiver of the present invention.

FIG. 2 is a diagram showing the relationship between the antenna rotation angle and the CN ratio value according to the embodiment of this invention.

FIG. 3 is a relationship diagram between an antenna rotation angle and a CN ratio value according to another embodiment of the present invention.

FIG. 4 is a block configuration diagram of a conventional vehicle-mounted satellite broadcast receiver.

[Explanation of symbols]

 1 Mixing Section 2 Front End 3 Video Processing Section 4 Audio Processing Section 5 CN Ratio Detection Section 6 Control Section (Microcomputer) 7A Antenna Control Section 7B Antenna Control Section

Claims (4)

[Claims] 1. Adjusting and fixing the elevation angles so that they are different from each other,
And, two antennas each provided with an azimuth angle rotation means, a mixing unit for mixing the received signal outputs of both antennas, a front end for amplifying and demodulating the output signal of the mixing unit, and an output from the front end. C of received signal
A CN ratio detecting unit for detecting an N ratio, and a control unit for controlling and driving the azimuth angle rotating means of the antenna by the output of the CN ratio detecting unit to change the azimuth angle so that the value of the CN ratio reaches a peak. An in-vehicle satellite broadcasting receiver comprising: 2. The in-vehicle satellite broadcast receiver according to claim 1, wherein the two antennas are adjusted and fixed to an elevation angle suitable for two regions adjacent to north and south. 3. The in-vehicle satellite broadcast receiver according to claim 1, wherein the two antennas have the same directivity direction and the same angular velocity and rotational direction. . 4. The two antennas are arranged such that their directivity directions are different from each other, while the rotation angular velocity and the rotation direction are the same.
The vehicle-mounted satellite broadcast receiver described in.