JP3219715B2 - Antenna tracking controller for broadcast satellite reception - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna control apparatus for receiving broadcast satellites installed in a mobile object, and more particularly to an improvement in tracking of an antenna accompanying movement of the mobile object.

[0002]

2. Description of the Related Art Conventionally, BS (B
roadcasting Satellite) The receiving antenna control device is BS
A receiving antenna is mounted on the roof of the mobile body, and the mobile body itself constantly moves on the ground, and in response to this movement, the antenna is directed to the broadcast satellite, which will be described in detail below.

FIG. 7 is a diagram for explaining a schematic configuration of a conventional antenna tracking control apparatus for receiving broadcast satellites. The broadcast satellite receiving antenna tracking control device shown in the figure includes a BS antenna 1 composed of a plurality of planar antennas for tracking a satellite, a phase comparator 2 for comparing the phases of the respective planar antennas 1, and a phase comparator. An A / D converter 3 (Analog to Digital Converter) for converting the analog signal 2 into a digital signal;
The control unit 4 includes a control unit 4 that forms a signal for controlling the driving of the BS antenna 1 from the compared phase data, and a motor 5 that drives the BS antenna 1 based on the control signal generated by the control unit 4. The planar antenna constituting the BS antenna 1 excites a large number of antenna elements formed on the antenna surface, and the received power is collected in a power supply unit via a power supply circuit and guided to a converter (not shown). The configuration of the power supply circuit includes a configuration using a film substrate (dielectric) and a configuration using a waveguide. Further, the antenna elements include a patch type and a slot type, and the latter include a radial slot type in which two orthogonal slot pairs are radially arranged and a helical array type in which helical elements are arranged concentrically. The control unit 4 determines the incident direction of the radio wave from the phase difference of the radio wave incident on the planar antenna, rotates the motor 5 until the phase difference between the two radio waves becomes zero, and causes the BS antenna 1 to face the direction of the broadcasting satellite. This will be described in detail below.

FIG. 8 shows the BS antenna 1 and the broadcasting satellite 1 shown in FIG.
It is a figure explaining the antenna satellite angle etc. between 00 and.
As shown in FIG. 3A, the angle between the normal line (maximum gain direction) of the BS antennas 1A and 1B and the incoming radio wave from the broadcasting satellite 100 is defined as θ. BS antenna 1
When A and 1B produce a path difference LA for the arriving radio wave,
If the antenna is moved so that LA = 0, that is, θ = 0, the antenna faces in the maximum gain direction and the reception level becomes maximum. This antenna satellite angle θ is multiplied by the signals received by the planar antennas 1A and 1B by the phase comparison unit 2,
High frequency components are removed and required. In this case, as shown in FIG. 3B, the planar antennas 1A and 1B have a planar antenna phase difference (Δθ) between the respective received signals corresponding to the antenna satellite angle θ.

FIG. 9 is a diagram for explaining the operation of the control unit 4.
You. The phase comparison unit 2 represents the amplitude of the received signal as A
And the output signal becomes, for example, A · sin θ.
If the phase is further shifted by 90 °, A · cos θ
Is obtained. Here, the control unit 4 performs as follows.
Obtain the amplitude A of the received signal and the phase difference Δθ of the planar antenna
You. A = ｛(A · sinΔθ)^Two+ (A · cosΔθ)^Two｝^1/2 ... (1) Δθ = tan^-1{A · sinΔθ / A · cosΔθ} = tan^-1tanΔθ (2) The reception amplitude A is the antenna satellite angle θ = 0,
(A) As shown in FIG.
Have a On the other hand, the antenna satellite angle θ is
Because it depends on the period of the signal from 100 and the path difference,
With respect to the antenna phase difference Δθ, as shown in FIG.
, There will be more than one. Therefore, BS Ant
Plane 1 to face the broadcast satellite 100
Antenna satellite corresponding to antenna phase difference Δθ = -180 °
Angle θ_-, Δθ = + 180 °, θ ₊As a book
A threshold value of the level of the received signal shown in FIG.
The tracking of the BS antenna 1 of the broadcasting satellite 100 is based on the received signal level.
Plane antenna phase difference when
This is performed so that Δθ becomes zero. Therefore, the control range
Is θ _-≤θ≤θ₊Becomes Therefore, outside of this range
Control will cause the motor 5 to rotate in the opposite direction.
Control is stopped. The tracking of this method is based on the BS
Azimuth and angle of attack between antenna 1 and broadcast satellite 100
Is

[0006]

However, in the conventional broadcasting satellite receiving antenna tracking control apparatus, the threshold level of the received signal needs to be larger than a certain value for the above-mentioned reason. If the level falls below the threshold value due to a regional difference, a weather difference, or the like, there is a problem that tracking control is lost.

[0007]

The present invention solves the above problems.
It was done to decide. The present invention controls the tracking of the broadcast satellite by receiving radio waves from a broadcast satellite with a plurality of antennas of a mobile object, controlling the direction of the antenna such that the antenna phase difference Δθ of each received signal becomes zero. In the broadcast satellite receiving antenna tracking control device, the antenna is obtained by the root mean square of each of the cosine component and the sine component of the phase difference .
Tracking when the amplitude of the received signal exceeds the threshold
Tracking means for performing control; and
Threshold changing method that changes based on the position information by the video device
And a step.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for receiving a radio wave from a broadcasting satellite with a plurality of antennas of a mobile body so that the antenna phase difference Δθ of a received signal becomes zero. In a broadcast satellite receiving antenna tracking control device that controls the tracking of the broadcast satellite by controlling the direction of the antenna,
When the amplitude (AcosΔθ) of the cosine component of the phase difference exceeds a first threshold, the tracking of the broadcast satellite is performed so that the phase difference of the received signal becomes zero. Further, in addition to the first threshold value, the amplitude of the received signal obtained by the root mean square of each of the cosine component and the sine component of the phase difference is -180.
The tracking of the broadcast satellite is performed so that the phase difference of the received signal becomes zero when the value exceeds the second threshold value which is a value outside the range of ° ≦ Δθ ≦ 180 ° and is not less than the side lobe value. Further, if the amplitude of the cosine component recovers within a predetermined time even if it falls below the first threshold value, the tracking of the broadcast satellite is continued. Further, the second threshold value is variable depending on the position of the moving object, and the threshold value is changed based on position data obtained by navigation of the moving object.

[0009]

According to the broadcast satellite receiving antenna tracking control apparatus of the present invention, if the amplitude of the received signal falls below the second threshold value and recovers within a predetermined time, the tracking of the broadcast satellite continues. As a result, loss of control hardly occurs even in the shadow of a building or the like, and stability is achieved. The threshold value is variable depending on the position of the moving body, and the threshold value is changed based on the position data obtained by navigation of the moving body, so that the regional difference in the electric field strength can be taken into account, so that the control is further stabilized.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a broadcast satellite receiving antenna tracking control device according to an embodiment of the present invention. The broadcast satellite receiving antenna tracking control device shown in this figure is basically based on the premise of FIG. 9 and includes a plurality of planar antennas, for example, 1A, 1A,
BS antenna 1 composed of B, 1C, and 1D, and converters 61, 62, 63, and 6 connected to BS antenna 1 and converting, for example, a reception frequency of 10 GHz to 1 GHz.
4, amplifiers 71, 72, 73 and 74 connected to the converters 61, 62, 63 and 64, and amplifiers 7
Phase comparison unit 21 connected to 1 and 72, 73 and 74
, 22 and A / D converters 31 and 32 connected to the phase comparison units 21 and 22, respectively, and connected to the A / D converters 31 and 32 to drive, for example, the azimuth of the BS antenna 1. Level change tracking control unit 41 that controls the motor 51 that drives the angle of attack of the BS antenna 1 and controls the tracking in consideration of the fluctuation of the received signal level due to the weather difference and the regional difference. Is provided.
The phase comparing unit 21 calculates a phase difference caused by a path difference between the planar antennas 1C and 1A and the plane antennas 1D and 1B. The phase comparison unit 22 calculates a phase difference caused by a path difference between the planar antennas 1C and 1D and the plane antennas 1A and 1B. The reception level fluctuation tracking control section 41 will be described in detail below. The outputs of the amplifiers 71, 72, 73 and 74 are output to the tuner for reproduction via the synthesizing unit 50.

FIG. 2 is a diagram for explaining a base technology of the present invention .
FIG. 3 is a diagram for explaining setting of a first threshold value in consideration of a relationship between a received signal level A and a function AcosΔθ.
FIG. 4 is a diagram for explaining setting of a first threshold value and a second threshold value in consideration of a relationship between a received signal level A and a function AcosΔθ. As shown in FIG. 2A, the functions AcosΔθ and AsinΔθ described above with reference to FIG. 9 are superimposed on the received signal level. The function AcosΔθ is symmetrical with respect to the antenna satellite angle θ = 0, and has a side lobe when it is away from θ = 0 as shown in FIG.
The peak width is narrower than that of. This is because the received signal level A is the mean square of the functions AcosΔθ and AsinΔθ. The first threshold value for the function AcosΔθ is set lower than the conventional threshold value and equal to or higher than the peak value of the side lobe. The antenna satellite angles θ + 1, θ-1 corresponding to the first threshold value are in a relationship of θ− <θ−1, θ + 1 <θ +. Therefore, if this first threshold value is used, the tracking control range is θ-1 ≦ θ ≦ θ + 1.

Next, as shown in FIG. 3, a second threshold value is set in place of the conventional threshold value. This second threshold is set lower than the conventional threshold and higher than the side lobe value of the received signal level. Therefore, the antenna satellite angles θ + 2 and θ−2 corresponding to the second threshold value are in the relation of θ−2 <θ− and θ + <θ + 2. The tracking control range using the first threshold and the second threshold will be described below.

FIG. 4 is a flowchart for explaining the operation of the first example of the reception level fluctuation tracking control section 41. In step S1 shown in the figure, the motor 51 for driving in the azimuth direction is rotated at a high speed in order to search for the broadcasting satellite 100. In step S2, the data from the phase comparison section 21 is taken into the A / D converter 31.

In step S3, the received signal level A
Is calculated according to the equation (1). In step S4, it is determined that AcosΔθ> first threshold. If this determination is "NO", the process returns to step S2. That is, tracking control is not performed. In step S5, if the above determination is "YES", tracking is started and servo control is performed.
Hereinafter, similar processes S2 ′, S3 ′, and S6 are performed.

As described above, since the first threshold value is lower than the conventional threshold value, the possibility of deviating from the tracking control is reduced even if the received signal level is lowered due to a weather difference, a regional difference, or the like. . FIG. 5 is a diagram for explaining the premise technology of the present invention .
5 is a flowchart for explaining the operation of the second example of the reception level fluctuation tracking control unit 41 of FIG. This figure differs from FIG. 4 in step S6. Step S4 ′ is Ac
osΔθ> first threshold (θ-1 ≦ θ ≦ θ + 1) and A
> The second threshold value (θ-2 ≦ θ ≦ θ + 2) is determined. In comparison with the above, the tracking starts when AcosΔθ> the first threshold, and the moving body rapidly rotates and AcosΔθ
Even if the first threshold is not satisfied, the tracking control can be performed if A> the second threshold is satisfied. This corresponds to the fact that the pull-in range is narrow and the lock-in range is wide, and it is possible to stably track the broadcasting satellite 100.

FIG. 6 is a flowchart for explaining the operation of the third example of the reception level fluctuation tracking control section 41 according to the embodiment of the present invention . First, the control unit 4 shown in FIG. 1 inputs longitude / latitude as position data from the navigation device 9 for deriving the moving position of the moving object. In step S20 of this figure, the motor 51 is rotated at a high speed for searching for the broadcasting satellite 100. In step S21, it is determined whether longitude / latitude data has been received from the navigation device 9. If this determination is "NO", the flow proceeds to step S23.

In step S22, the above judgment is made as "Y
If "ES", the level of the second threshold shown in FIG. 3 is converted as shown in Table 1.

[0018]

[Table 1]

The reason why the second threshold value is converted in this way is that it is known in advance that there is a regional difference in the electric field intensity of the radio wave from the broadcasting satellite 100 in Japan. The information is fetched and the value of the second threshold value is changed as shown in Table 1. The converted value of the second threshold value in Table 1 is stored in the area / reception level conversion memory 10 in the control unit 4.

In step S23, the phase comparison unit 21
Is taken into the A / D converter 31. In step S24, the calculation of the received signal level A is performed according to equation (1). In step S25, A> the second threshold value is determined. If this determination is "NO", the process returns to step S21.

In step S26, the motor 51 is rotated at a constant speed for the tracking operation. In step S27, it is determined whether longitude / latitude data has been received from the navigation device 9. If this determination is "NO", the flow proceeds to step S29. If the determination is "YES" in step S28, the value of the second threshold value is changed according to Table 1.

In step S29, Δθ is determined according to equation (2). In step S30, the rotation speed of the motor 51 corresponding to Δθ is calculated, and for example, PID (Pro
portional plus Integral plus Derivative action) control. In step S31, a motor rotation speed command is issued.

In step S32, the phase comparator 21
Is taken into the A / D converter 31. In step S33, the received signal level is calculated according to the equation (1), and the process returns to step S27 to repeat the tracking operation.

[0024]

As described above, according to the present invention, even if the amplitude of the received signal falls below the second threshold value, if the signal is recovered within a predetermined time, the tracking of the broadcast satellite is continued. Even when the building is in the shadow of a building or the like, loss of control is less likely to occur, and the building is stabilized. The value of the second threshold is variable depending on the position of the moving object, and the value of the second threshold is changed based on the position data obtained by navigation of the moving object, so that the regional difference in the electric field strength can be considered. Therefore, the control is further stabilized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a broadcast satellite receiving antenna tracking device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating setting of a first threshold value in consideration of a relationship between a received signal level and a function AcosΔθ.

FIG. 3 is a diagram illustrating setting of a first threshold value and a second threshold value in consideration of a relationship between a received signal level A and a function AcosΔθ.

FIG. 4 is a flowchart illustrating an operation of a first example of a reception level fluctuation tracking control unit 41;

FIG. 5 is a flowchart illustrating an operation of a second example of the reception level fluctuation tracking control unit 41.

FIG. 6 is a flowchart illustrating an operation of a third example of the reception level fluctuation tracking control unit 41.

FIG. 7 is a diagram showing a schematic configuration of a conventional broadcast satellite receiving antenna control device.

8 is a diagram illustrating an antenna satellite angle and the like between the BS antenna 1 and the broadcast satellite 100 in FIG. 7;

FIG. 9 is a diagram for explaining the operation of the control unit 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... BS antenna 2, 21, 22 ... Phase comparison part 3, 31, 32 ... A / D converter 4 ... Control part 8 ... Clock 9 ... Navigation 10 ... Conversion memory 41 ... Reception level fluctuation tracking control part 51, 52 ... Motor 100 ... Broadcast satellite

Continuation of front page (56) References JP-A-8-18324 (JP, A) JP-A-6-314922 (JP, A) JP-A-7-287061 (JP, A) JP-A-6-174817 (JP) JP-A-4-339213 (JP, A) JP-A-4-2206 (JP, A) JP-A-1-156686 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB G01S 3/00-3/74 H01Q 1/00-3/46

Claims (1)

(57) [Claims] 1. A radio wave from a broadcasting satellite is received by a plurality of antennas of a mobile body, and the direction of the antenna is controlled so that an antenna phase difference Δθ of each received signal becomes zero, and tracking control of the broadcasting satellite is performed. A tracking antenna control apparatus for receiving broadcast satellites, wherein the squared square of each of the cosine component and the sine component of the phase difference
If the amplitude of the received signal obtained by the
Tracking means for performing the tracking control at a time, and the threshold value is determined by the navigation device of the moving object.
Broadcast satellite receiving antenna tracking of the threshold value change means for changing, based on the position information, characterized in that it comprises a
apparatus.