JPH06303175A - Satellite broadcasting receiver - Google Patents

Abstract

PURPOSE:To obtain a satellite broadcasting receiver where the presence or absence of a broadcasting wave is checked, the switching of a channel is smoothly performed not so as to generate a discrepancy in a reproduced image and voice and the tracking of a broadcasting satellite is made possible even if a channel in which the broadcasting wave does not exist is selected. CONSTITUTION:This receiver is provided with a still image circuit 9 where reception image signals demodulated by a satellite broadcasting receiver are held and updated and a selection switch 10 selecting either one of the demodulated reception image signal or the image signal just before it is held in the still image circuit. When a user selects a channel in which the broadcasting wave does not exist at the time of receiving a satellite broadcasting by a mobile object and the information (the phases and amplitudes of the broadcasting waves) necessary for the attitude control of an antenna 1 is lost, the selection switch 10 is controlled by a controller 6, the image signal held in the still image circuit 9 is outputted, the channel in which the broadcasting wave exists is selected as a still image is displayed on a monitor 11 and the attitude control of the antenna 1 is performed. When the channel in which the broadcasting wave exists is selected, the display of a monitor 11 is switched from the still image to a reception image.

Description

Detailed Description of the Invention

[0001]

The present invention relates to satellite broadcasting (hereinafter, BS).
In particular, the present invention relates to a satellite broadcast receiving apparatus suitable for mounting on a mobile body.

[0002]

2. Description of the Related Art (1) As one of satellite tracking systems for mobile antennas, there is a phase monopulse system shown in FIG. 6 is an explanatory diagram showing the relationship between the antenna of the device of FIG. 5 and the direction of the received radio wave. In the phase monopulse system, as shown in FIG. 6A, when the antennas 53 and 54 mounted on the turntable 51 in FIG. 5 are oriented in the direction perpendicular to the radio wave arrival direction, two antennas are used. 53,5
Since 4 is equidistant from the satellite, the received signals are both cos
(Ω ₀ t), and on the other hand, as shown in FIG. 6B, when the antennas 53 and 54 are deviated from the arrival direction of the radio wave, the phase difference φ is generated due to the deviation of the distance from the satellite. The received signal is cos (ω ₀ t), and the received signal of the antenna 54 is cos (ω ₀ t + φ). The motor 52 is controlled by detecting this phase difference. In this case, the reception signal received by the antenna 53 is input to the frequency converter 56 and the frequency converter 57, and the output of the frequency converter 56 is 90 °.
The output of the phase shifter 58 and the output of the frequency converter 57 are input to the phase comparator 59, the high frequency component signal is removed by the LPF 60 to obtain a direct current signal, and the DC signal is obtained. 52 is controlled.

(2) Further, as one of the methods for tracking a satellite with one antenna, there is a step trax method shown in FIG. In the step-track method, the output of the antenna 73 in FIG. 7 is passed through the frequency converter 74 and then converted by the level detector 75 into the direct placement according to the received value level. Then, if the turntable 71 is moved in a certain direction and the direction of the antenna 73 is slightly changed, the reception level becomes high when the antenna approaches the direction of the satellite, and conversely, the reception level becomes low when the antenna is moved away from the satellite. The level change detection circuit 76 detects this change in the reception level, and the motor drive circuit 77 is controlled by this detection signal to control the rotation of the motor 72. In the above-mentioned conventional system, since the monopulse system of 1 uses the phase monopulse and the amplitude monopulse, a plurality of sets of antennas and frequency converters are required, and a synthesis circuit is also required, which complicates the overall configuration of the receiving device. In addition, the step track method of (2) uses a single antenna and a frequency converter, but the turntable including the antenna has a large inertia, resulting in poor response and a drastic change in posture. There was a problem that it could not be used for.

(3) The invention disclosed in Japanese Patent Laid-Open No. 3-327095 (Name: "Satellite tracking receiver for mobile antenna") for improving such drawbacks and problems.
(See FIGS. 8 and 9). In FIG. 8, the output of the antenna 83 passes through the frequency converter 84 and is then converted by the level detector 85 into a DC signal corresponding to the reception level. The level change detection circuit 86 detects the level change of the DC signal,
The level detection circuit 86 switches the switch 87 according to the detected level change. At this time, the switch 87 is switched only when the level detection circuit 86 detects a decrease in the level, and is not switched when the level is increased. The switch 87 switches between + V and -V voltages according to the detection signal of the level change detection circuit 86, and the adder 89 outputs the + V and -V voltages and the output voltage ωg of the angular velocity sensor 88.
Is added. The motor drive circuit 90 switches the rotation direction of the motor 82 according to the sign of the output of the adder 89.

[0005]

When the broadcasting satellite is tracked by the signal level of the received broadcast wave as in the case of the above (3), if a channel in which no broadcast wave exists is tuned in, a building or the like may cause a problem. As in the case of shielding, the signal level drops and the antenna moves to search operation. in this case,
The longer it takes to select a channel with a broadcast wave, the wider the range is searched due to sensor (level change detection circuit) errors, etc., so it takes longer for the antenna to point to the broadcasting satellite. (See FIG. 9) In many cases, there was a problem.

The present invention has been made in view of the above problems. In the reception of satellite broadcasting, the presence or absence of a broadcast wave is checked while performing the tracking operation of the broadcasting satellite, and the channel switching is smoothly performed so that the reproduced image and the sound are reproduced. It is an object of the present invention to provide a satellite broadcast receiving apparatus that does not cause a contradiction and enables tracking of a broadcast satellite even if a channel for which broadcasting is not present is selected.

[0007]

In order to achieve the above object, the satellite broadcast receiving apparatus of the first invention is a frequency conversion means for converting a reception signal from an antenna provided in a mobile body into a predetermined frequency signal. And a antenna control means for detecting the deviation of the antenna with respect to the satellite direction based on the frequency signal and drivingly controlling the direction and rotation speed of the antenna so as to track the antenna according to the detection result. In, the control signal output means for detecting the level change of the frequency signal from the antenna and outputting the control signal, and when the reception level is equal to or more than a predetermined value, holds / updates the image signal based on the frequency signal from the frequency conversion means and receives it. A still image signal output means for outputting the held image signal when the level is less than a predetermined value, and a frequency based on the control signal from the control signal output means. And having a selection means for selecting one of the image signal from the image signal or a still image signal output means based on the frequency signal from the switch means.

A second aspect of the present invention is the satellite broadcast receiving apparatus of the first aspect, further including a channel selecting means for selecting a broadcast channel, and as a result of channel selection by the channel selecting means, the reception level becomes less than a predetermined value. At this time, based on the control change signal from the control signal output means, the selection means selects the image signal from the still image signal output means, and the antenna control means receives the broadcast wave whose reception level is equal to or higher than a predetermined value. When the channel of the broadcast wave is selected by the tuning unit, and the channel of the broadcast wave can be received by the antenna control unit based on the drive control of the antenna by the antenna control unit. Selects the image signal based on the frequency signal from the frequency conversion means based on the control signal from the control signal output means.

[0009]

With the above arrangement, the satellite broadcast receiving apparatus of the first invention detects the level change of the frequency signal from the antenna by the control signal output means and outputs the control signal. Further, the still image signal output means holds / updates the image signal based on the frequency signal from the frequency conversion means when the reception level is equal to or higher than a predetermined value, and outputs the held image signal when the reception level is lower than the predetermined value. Then, the selection means selects either the image signal based on the frequency signal from the frequency conversion means or the image signal from the still image signal output means based on the control signal from the control signal output means. A second aspect of the present invention is the satellite broadcast receiving device according to the first aspect, wherein when the channel selection by the channel selection means results in the reception level being less than a predetermined value,
Based on the control change signal from the control signal output means, the selection means selects the image signal from the still image signal output means, and the antenna control means drives the antenna so as to receive a broadcast wave whose reception level is equal to or higher than a predetermined value. When the channel of the broadcast wave is controlled by the antenna control means, it becomes possible to receive the broadcast wave whose reception level is equal to or higher than a predetermined value based on the control of the antenna drive, and the channel selection means controls the selection means. The image signal based on the frequency signal from the frequency conversion means is selected based on the control signal from the signal output means.

[0010]

Embodiment 1 FIG. 1 is a block diagram of an embodiment of a satellite broadcast receiving apparatus according to the present invention, and FIG. 2 is a flow chart for explaining an operation when searching for a radio wave arrival direction. . In FIG. 1, 1 is an antenna and 2 is an LNB
(Low noise block) 3 is an elevation motor, 4 is a turntable, 5 is an azimuth motor, 6 is a controller, which corresponds to control signal output means, 7 is a tuner, 8 is a tuning switch, which is equivalent to tuning means. Reference numeral 9 is a still picture circuit, which corresponds to still picture signal output means, 10 is a switch, which corresponds to selection means, and 11 is a monitor. Further, the motors 3 and 4 and the controller 6 constitute an antenna control means.

In FIG. 1, the controller 6 monitors the reception level output from the tuner 7 and adjusts the elevation angle and azimuth angle of the antenna 1 so as to obtain a good reproduced image.
Control two motors.

The still picture circuit 9 holds and updates the image signal from the tuner 7 when the signal level of the tuner 7 is above a predetermined value, and outputs the held image signal when the signal level is below a predetermined value.

The controller 6 switches the switch 10 so as to select the image signal held in the still image circuit 9 as the output image signal when the reception level is lowered.
When the reception level rises again, the switch 10 selects the reception image signal as the output image signal.

Therefore, when the user tunes to a channel in which no broadcast wave is present and the information (phase and amplitude of the broadcast wave) required for antenna attitude control is lost when the mobile unit receives satellite broadcasts, the controller 6 is used. While the still image is displayed on the monitor 11 by controlling the selection switch 10, the attitude of the antenna 1 is controlled by selecting the channel in which the broadcast wave exists, and when the channel in which the broadcast wave exists is selected, the display on the monitor 11 is displayed. It is possible to switch from a still image to a received image, and to provide a continuously smooth receiving operation.

In this embodiment, the still picture circuit is used as the still picture signal output means, but the present invention is not limited to this, and a Boolean back circuit or a video meeting circuit may be used. The operation of the controller 6 when the receiving channel is changed will be described below with reference to the flowchart of FIG.

When the tuning switch 8 is pressed (S1), the selected channel number is stored in the register C1 (S1).
2) The switch 10 is switched to output a still image as an output image.

When the satellite broadcast can be received, the currently selected channel number is saved in the register C0 (S
4, S5), the channel of the register C1 is selected. If satellite broadcasting is not received, the channel of register C1 is selected (S4, S6).

If the channel of the register C1 can be received, the switch 1 outputs the received image as an output image.
0 is switched (S7, S11) and the channel is determined (S7).
12) and returns to S1.

If the channel of the register C1 cannot be received, the channel of the register C0 is selected again (S
8, S9), if it can be received here, it is determined that there is no broadcast wave in the channel of the register C1 and the channel of the register C0 is received with the output image being a still image (S10,
S11), the channel is determined (S12), and the process returns to S1.

When the channel of the register C0 cannot be received, it is considered that the radio wave is blocked, and S1 and S1
After 3 (since the channel is undetermined), the mode is changed to the search mode (while the channel of the register C0 is selected), and the attitude of the antenna 1 is controlled so as to search the arrival direction of the radio wave.

Then, in S4, it is determined whether or not the signal was successfully received, and the execution of S5 and the subsequent steps is repeated according to the result. Note that muting of voice is also performed at the same timing and procedure as switching of output images.

FIG. 3 shows a timing chart of the operation of FIG. In FIG. 3, “reception possible / impossible” indicates that reception is possible at the H level, and “search” indicates that the antenna control is in the search mode at the H level.
Further, in the "tuned channel", 7ch and 11ch are channels in which broadcast waves exist, and 13ch are channels that do not exist.

<Embodiment 2> FIG. 4 is a block diagram of another embodiment of the satellite broadcast receiving apparatus according to the present invention. The "antenna for a mobile body" disclosed in the above-mentioned Japanese Patent Laid-Open No. 327095/1993 is described as a conventional example. This is an example in which the present invention is applied to "satellite tracking receiver of".

In FIG. 4, 31 is a turntable on the moving body, 32 is its drive motor, and 33 is the turntable 31.
An antenna mounted on top, 34 is a frequency converter corresponding to frequency conversion means, 35 is a level detector, 36 is a level change detector, 37 is a switch for selecting + V or -V, and 38 is a corner. An acceleration sensor, 39 is an adder, and 40 is a motor drive circuit, which drives and controls the direction and rotational speed of the antenna 43 so as to track the antenna 43 according to the output of the adder 49. Reference numeral 41 is a demodulation circuit, 42 is a still image circuit, 43 is a switch, which corresponds to selection means, and M is a motor.

Further, the switch 37 and the angular acceleration sensor 3
8, the adder 39, and the motor drive circuit 40 compose antenna control means, and the level detector 5 and level change detector 6 compose control signal output means.

In FIG. 1, the output of the antenna 3 passes through the frequency converter 4 and is then converted by the level detector 5 into a DC signal corresponding to the reception level. The level change detection circuit 6 detects the level change of the DC signal, and switches the switches 7 and 13 according to the detected level change.

The switch 7 switches the voltage between + V and -V according to the detection signal of the level change detection circuit 6, and the adder 9 outputs the + V and -V voltages and the output voltage ωg of the angular velocity sensor 8.
Is added. The motor drive circuit 10 switches the rotation direction of the motor 2 according to the sign of the output of the adder 9.

The still picture circuit 12 holds and updates the image signal from the demodulation circuit 11 when the signal level of the level detector 5 is above a predetermined value, and when the signal level is below the predetermined value, the held image signal is held. Output.

The switch 13 is switched so as to select the still picture signal held in the still picture circuit 12 as the immediately preceding output picture signal when the reception level is lowered by the detection signal of the level change detection circuit 6, and the reception level is again set. When the voltage rises, the current reception image signal from the demodulation circuit 11 is switched to be selected as the output image signal.

[0030]

As described above, according to the satellite broadcast receiving apparatus of the present invention, it is possible to select a channel without a feeling of strangeness while moving. Further, the procedure that occurs when the channel arrangement of the broadcast wave is changed, for example, the registration of the preset memory, etc. becomes unnecessary.

[Brief description of drawings]

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

FIG. 2 is a flowchart for explaining an operation when searching for a radio wave arrival direction.

FIG. 3 is an operation timing chart of FIG.

FIG. 4 is a block diagram of another embodiment of the satellite broadcast receiving device according to the present invention.

FIG. 5 is a conventional example of a satellite broadcast receiving device (phase monopulse system).

6 is an explanatory diagram showing the relationship between the antenna of the device of FIG. 5 and the direction of received radio waves.

FIG. 7 is a conventional example of a satellite broadcast receiving device (step trax method).

FIG. 8 is a conventional example of a satellite broadcast receiving device.

9 is an explanatory diagram of an antenna search range by the apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 antenna 6 controller (control signal output means) 8 channel selection switch (channel selection means) 9 still image circuit (still image signal output means) 10 switch (selection means)

Claims (2)

[Claims] 1. A frequency conversion means for converting a reception signal from an antenna provided in a mobile body into a predetermined frequency signal, and detecting the deviation of the antenna with respect to the satellite direction based on the frequency signal, and detecting the deviation based on the detection result. In a satellite broadcast receiving device comprising: an antenna control means for drivingly controlling the direction and rotation speed of the antenna so as to track the antenna, a control signal for detecting a level change of a frequency signal from the antenna and outputting a control signal. Output means and a still image signal for holding and updating the image signal based on the frequency signal from the frequency converting means when the reception level is above a predetermined value, and outputting the held image signal when the reception level is below a predetermined value Output means and an image signal based on the frequency signal from the frequency conversion means based on the control signal from the control signal output means. Satellite broadcast receiving apparatus characterized by having a selection means for selecting one of the image signals from the still image signal output means. 2. A frequency conversion means for converting a reception signal from an antenna provided in a mobile body into a predetermined frequency signal, and detecting the deviation of the antenna with respect to the satellite direction based on the frequency signal, and detecting the deviation based on the detection result. In a satellite broadcast receiving device comprising: an antenna control means for drivingly controlling the direction and rotation speed of the antenna so as to track the antenna, a control signal for detecting a level change of a frequency signal from the antenna and outputting a control signal. Output means and a still image signal for holding and updating the image signal based on the frequency signal from the frequency converting means when the reception level is above a predetermined value, and outputting the held image signal when the reception level is below a predetermined value Output means and an image signal based on the frequency signal from the frequency conversion means based on the control signal from the control signal output means. Selection means for selecting one of the image signals from the still image signal output means, and channel selection means for selecting a broadcast channel,
When the reception level becomes less than a predetermined value as a result of channel selection by the channel selection unit, the selection unit selects the image signal from the still image signal output unit based on the control change signal from the control signal output unit. At the same time, the antenna control means drives and controls the antenna so as to receive a broadcast wave having a reception level equal to or higher than a predetermined value, and reception of the broadcast wave having a reception level equal to or higher than the predetermined value is performed based on the antenna drive control by the antenna control means. When the channel of the broadcast wave is selected by the channel selection unit, the selection unit selects the image signal based on the frequency signal from the frequency conversion unit based on the control signal from the control signal output unit. A satellite broadcasting receiver characterized by.