JP2704058B2 - Satellite signal receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention selects and demodulates a television signal of a desired satellite and a desired channel from transmission signals from a plurality of artificial satellites such as a broadcasting satellite and a communication satellite received by a receiving antenna. And a satellite signal receiving device for extracting a video signal and the like.

[0002]

2. Description of the Related Art Conventionally, in this type of apparatus, a channel selection circuit selects a television signal of a desired satellite / desired channel from output signals from a receiving antenna and converts the signal into an intermediate frequency signal. After amplifying to a predetermined level by an amplifier circuit having an automatic gain adjustment circuit (AGC circuit), the PLL
The signal is demodulated by an FM demodulation circuit of the system.

[0003] On the other hand, the transmission radio wave from a satellite has a different frequency shift for each satellite and each channel. Therefore, in order to obtain a good image without noise, a reception satellite and a reception channel for which a channel is selected by a channel selection circuit. Each time, it is necessary to change the demodulation bandwidth of the FM demodulation circuit according to the frequency shift.

Therefore, conventionally, in this type of device, a variable attenuator is provided in a transmission path of an intermediate frequency signal from an amplifier to an FM demodulator, and the amount of attenuation of the variable attenuator is adjusted to provide the FM demodulator. By adjusting the level of the input intermediate frequency signal, the demodulation bandwidth of the FM demodulation circuit can be set for each receiving satellite and each receiving channel in accordance with the frequency shift (for example, see Japanese Unexamined Patent Application Publication No. 62-1
No. 47893).

[0005]

However, when the demodulation bandwidth of the FM demodulation circuit can be set by using the variable attenuation circuit as described above, every time the receiving satellite and the receiving channel are changed, the channel signal is changed. In accordance with the frequency shift, it is necessary to adjust the amount of attenuation of the variable attenuation circuit so that noise does not occur in the image.

Further, in accordance with the frequency shift of the signal of the channel to be received, for example, when the frequency shift is wide, FM
When the output level from the demodulation circuit increases, the image becomes brighter. Conversely, when the frequency shift is narrow, the image level becomes darker because the output level from the FM demodulation circuit decreases.

The present invention has been made in view of such a problem, and provides a satellite signal receiving apparatus which can always obtain an image of constant brightness without noise regardless of the frequency shift of a radio wave transmitted from a satellite. Made for the purpose of doing.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a method for receiving output signals from one or a plurality of receiving antennas for receiving radio waves transmitted from a plurality of artificial satellites. , A tuning circuit for selecting a television signal of a predetermined satellite and a predetermined channel corresponding to a tuning command from the outside and converting it to an intermediate frequency signal, and converting the intermediate frequency signal from the tuning circuit to a signal of a certain level. In AGC circuit
A built-in amplifier circuit, a PLL type FM demodulation circuit for demodulating the amplified intermediate frequency signal, and a video signal amplification circuit for amplifying a video signal included in a demodulated signal from the FM demodulation circuit. In the satellite signal receiving device, a first variable attenuation circuit provided on an input side of the FM demodulation circuit, a second variable attenuation circuit provided on an input side or an output side of the video signal amplifying circuit, For each satellite / channel for which the station circuit selects a channel, the larger the frequency shift of the transmission radio wave, the higher the frequency shift of the transmission radio wave from the satellite.
The amount of attenuation of the first variable attenuation circuit is small,
The attenuation of the attenuation circuit increases, and the frequency
The smaller the shift, the larger the attenuation of the first variable attenuation circuit.
The amount of attenuation of the second variable attenuation circuit is reduced.
, The attenuation amount storage means for each store attenuation preset the first and second variable attenuation circuit, the first of the tuning circuit corresponds to the satellite and channel performing channel selection
And an attenuation adjustment means for reading the attenuation of the second variable attenuation circuit from the attenuation storage means, and adjusting the attenuation of the first and second variable attenuation circuits to the read attenuation.
It is characterized by having provided.

[0009]

In the satellite signal receiving apparatus of the present invention configured as described above, first, the channel selection circuit selects a predetermined satellite and a predetermined channel corresponding to a channel selection command from the outside from the output signals from the reception antenna. The TV signal is selected and converted to an intermediate frequency signal, and the amplifier circuit operates the built-in AGC circuit.
Therefore, the intermediate frequency signal from the tuning circuit is amplified to a signal of a certain level . Then the constant output from this amplifier circuit
The intermediate frequency signal of the level is input to the FM demodulation circuit via the first variable attenuation circuit, and is demodulated by the FM demodulation circuit. The demodulated signal from the FM demodulation circuit is input to a video signal amplification circuit, and the video signal amplification circuit selectively amplifies the video signal included in the demodulated signal. Further, since the second variable attenuation circuit is provided on the input side or the output side of the video signal amplifier circuit, the demodulated signal input to the video signal amplifier circuit or the video signal output from the video signal amplifier circuit 2 is attenuated by the variable attenuation circuit.

[0010] On the other hand attenuation amount storage unit, for each satellite the channel tuning circuit performs channel selection, in correspondence with the transmission radio wave of the frequency deviation from the satellite, the frequency shift of the transmitted radio wave
The larger the value, the smaller the attenuation of the first variable attenuation circuit
The attenuation of the second variable attenuation circuit increases, and the transmission power
As the frequency shift of the wave is smaller, the first variable attenuation circuit
The amount of attenuation is large and the amount of attenuation of the second variable attenuation circuit is small.
The preset attenuation amounts of the first and second variable attenuating circuits are respectively stored, and when the tuning circuit performs tuning, the attenuation amount adjusting means is provided with the tuning circuit. Reads the attenuation amounts of the first and second variable attenuation circuits corresponding to the satellite and the channel to be selected from the attenuation amount storage means,
The attenuation of the first and second variable attenuation circuits is adjusted to the read attenuation. That is, the satellite signal receiving apparatus of the present invention
First, a predetermined satellite / location output from the channel selection circuit
Intermediate frequency signal of constant channel TV signal to amplifier
To a constant level signal,
The wave signal is transmitted by the attenuation adjustment means
Attenuation is adjusted according to the frequency shift (or bandwidth) of the
Input to the FM demodulation circuit via the first variable attenuation circuit
The intermediate frequency that can be demodulated by the FM demodulation circuit
Match the signal bandwidth to the bandwidth of the selected TV signal.
Let Also, the transmission radio wave of the selected TV signal
The attenuation of the first variable attenuation circuit is adjusted in accordance with the frequency shift of
If adjusted, a high S / N ratio without noise in the FM demodulation circuit
A demodulated signal is obtained, and the video signal included in the demodulated signal is
Clear image without noise if input to TV receiver etc.
Can be reproduced from the FM demodulation circuit.
The output demodulated signal has a small frequency shift of the received radio wave.
Therefore, the larger the attenuation of the first variable attenuation circuit,
Since the signal level is low, it is not included in the demodulated signal.
Video signal, the larger the attenuation of the first variable attenuator,
(In other words, the frequency of the transmitted radio wave of the selected TV signal
The smaller the deviation), the lower the signal level. And
In general, the lower the signal level of the video signal is,
Darkening is well known. However, FM demodulation
Video signal that amplifies the video signal included in the demodulated signal from the road
A second variable attenuator on the input side or output side of the signal amplifying circuit
And the second variable attenuation circuit is provided by the attenuation amount adjusting means.
The amount of attenuation of the path is adjusted according to the frequency shift of the
Thus, the larger the frequency shift (in other words, the first variable
The smaller the attenuation of the attenuation circuit), the second variable attenuation circuit
By adjusting so that the amount of attenuation of
The signal level of the video signal output from the device can be kept constant.
Because As a result, according to the present invention, the FM demodulation circuit
To improve the S / N ratio of the demodulated signal output from
Not only can you obtain clear images without blur, but also the video signal amplification
Make sure that noise does not increase before or after the circuit.
The brightness of the playback image can be kept constant
Become like

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a block diagram showing a configuration of an entire satellite signal receiving apparatus according to an embodiment to which the present invention is applied.

As shown in FIG. 1, a satellite signal receiving apparatus 1 of the present embodiment receives a signal at a plurality of receiving antennas 3 and a predetermined frequency band (1 GHz) at a converter 5 of each receiving antenna 3.
A plurality of artificial satellites converted to signals of the band {Broadband satellite BS, communication satellite JC of Japan Communication Satellite Co., Ltd.
Transmission signals from the SAT and the communication satellite Superbird II of Space Communications Co., Ltd. are mixed by the mixer 7 and input via one coaxial cable 9.

The input signal is first selected in the satellite signal receiving apparatus 1 by selecting a television signal of a predetermined satellite and a predetermined channel designated from the outside from the signal, and the intermediate signal having a center frequency of 402.78 MHz is selected. The signal is input to a tuning circuit 11 which converts the signal into a frequency signal. The tuning circuit 11 is a well-known circuit comprising a local oscillation circuit 13 and a frequency conversion circuit 15, and intermediately converts a television signal of a predetermined channel determined by an oscillation frequency of the local oscillation circuit 13 (hereinafter, referred to as a local oscillation frequency). Convert to frequency signal. Note that this local oscillation frequency is
It is controlled by a control circuit 50 described later.

Next, an output signal from the tuning circuit 11 is an intermediate frequency filter 17 for passing only the intermediate frequency signal, and an AGC circuit built-in type for amplifying the intermediate frequency signal passing through the filter 17 to a signal of a predetermined level. And an intermediate frequency amplifying circuit 19. The intermediate frequency signal amplified to a predetermined level by the amplifier circuit 21 is passed through a first variable attenuator circuit 23 to output a PLL type F signal.
The signal is input to the M demodulation circuit 25 and demodulated into a DC to 9 MHz television signal.

As shown in FIG. 2, the first variable attenuation circuit 23 sets the demodulation bandwidth of the FM demodulation circuit 25 to any of 24 MHz, 27 MHz, and 30 MHz based on the amount of attenuation A. , The attenuation amount A can be changed to three stages of 0 [dB], α [dB], and β [dB]. In FIG. 2, X is the maximum frequency that can be demodulated by the FM demodulation circuit 25, Y is the minimum frequency that can be demodulated by the FM demodulation circuit 25,
f0 represents the center frequency of the demodulation band.

That is, the first variable attenuator 23 is a well-known π-type attenuator composed of three PIN diodes D1, D2 and D3, as shown in FIG. Three transistors T
By turning on one of R1, TR2, and TR3, the cathode side potential of the PIN diode D1 provided in series between the input and the output is switched in three stages, whereby the attenuation A is reduced to 0 [dB]. α [dB], β [dB]
(Where 0 <α <β) and the demodulation bandwidth of the FM demodulation circuit 25 is changed to 24 MHz, 27 MHz, and 30 MHz.
Hz can be adjusted in three stages.

In FIG. 3, L1 is a choke coil that blocks high-frequency components and passes only DC components. Also, a resistor R1, a variable resistor VR1 and a resistor R2
Is a series circuit composed of transistors TR1, TR2,
Ground resistors RX1 and R2 having different resistance values connected to TR3
A voltage dividing resistor circuit for setting the cathode side potential of the PIN diode D1 in cooperation with X2 and RX3 so that the attenuation A can be finely adjusted by manually adjusting the resistance value of the variable resistor VR1. Have been.

Next, the television signal demodulated by the FM demodulation circuit 25 is input to an audio signal processing circuit 27 and a video signal processing circuit 29, respectively. In the audio signal processing circuit 27, the audio subcarrier (5.7272) of the input television signal is output.
Signal processing for extracting an audio signal of 20 Hz to 20 kHz from 72 MHz) is performed, and the audio signal is output to an external device such as a television receiver via an audio output terminal 30a.

On the other hand, the video signal processing circuit 29 includes a second variable attenuating circuit 31 for attenuating the television signal demodulated by the FM demodulating circuit 25, and DC to DC signals from the television signal passing through the second variable attenuating circuit 31. And a video signal amplifying circuit 33 for selecting and amplifying only the 4.5 MHz video signal.
b to an external device such as a television receiver.

The second variable attenuating circuit 31 changes the level of the output signal from the FM demodulation circuit 25 and the level of the video signal output from the video signal processing circuit 29 in accordance with the frequency shift of the signal of the channel to be received. The adjustment is for preventing the brightness of the image from changing, and the control signal from the control circuit 50 controls the amount of attenuation B to 9.
It can be changed to three stages of 8 [dB], 9.1 [dB], and 11.3 [dB].

That is, as shown in FIG. 4, the second variable attenuating circuit 31 includes variable resistors VR11, VR12, VR13 and a resistor R.
Y1, RY2, RY3 and transistors TR11, TR12, T
It is composed of three types of grounding circuits consisting of R13 and a resistor R3. By turning on one of the transistors TR11, TR12 or TR13 by a control signal from the control circuit 50, the amount of attenuation B is reduced in the above three stages. Can be changed to

In order to change the amount of attenuation B in three stages,
Resistors having different resistance values are used for the resistors RY1, RY2, and RY3. Each transistor TR11, TR1
2, TR13 are connected to the variable resistors VR11, VR12, VR13, so that each of the variable resistors VR11, VR12, V13
By manually adjusting the resistance value of R13, the grounding resistance of each grounding circuit, and thus the three types of attenuation B, can be finely adjusted.

Next, a control circuit 50 for controlling the local oscillation frequency of the local oscillation circuit 13 and the attenuation amounts A and B of the respective variable attenuation circuits 23 and 31 includes a CPU 51, a ROM 53, a RAM 55, an input / output (I / O) port 57. , And a well-known microcomputer comprising a bus line 59 connecting these components, and functions as an attenuation adjusting means.

That is, the control circuit 50 is provided with a satellite selection switch 63 provided on the operation panel 61 of the receiver 1.
By receiving a tuning command from the tuning switch 65 or a tuning command from the remote control transmitting unit 69 input via the remote control receiving unit 67, the control unit executes a tuning process described later, and serves as an attenuation amount storage unit. 5, the local oscillation frequency of the local oscillation circuit 13, the attenuation amount A of the first variable attenuation circuit 23, and the second variable amount based on the channel selection data for each satellite and each channel shown in FIG. The attenuation amount B of the attenuation circuit is controlled.

Of the channel selection data stored in the ROM 53, the attenuation amounts A and B are respectively optimum for the frequency shift (hereinafter also referred to as deviation) of the radio wave transmitted from the satellite. The initial value is set in advance, and the satellite signal receiving device 1 of the present embodiment operates the remote control transmitting unit 69 to input a change command of the attenuation amount A or B to the control circuit 50, so that the control circuit 50 By executing an initial value changing process described later, the initial values of the attenuation amounts A and B can be changed for each channel of each satellite and stored in the RAM 55. When the attenuation values A and B have been changed by the initial value changing process, the control circuit 50 stores the changed attenuation amounts A and B in the RAM 5.
5 to control the attenuation A of the first variable attenuation circuit 23 and the attenuation B of the second variable attenuation circuit.

Hereinafter, the tuning process and the initial value changing process executed by the control circuit 50 will be described with reference to the flowcharts shown in FIGS. First, FIG. 6 is a flowchart illustrating a tuning process repeatedly executed when power is supplied to the satellite signal receiving device 1. As shown in the figure, when this tuning process is started, first, in step 100, the name of the currently selected satellite is read by a command signal from the satellite selection switch 63 or the remote controller transmitter 69, and in step 110, Tuning switch 65
Alternatively, the currently selected channel is read in accordance with a command signal from the remote control transmitter 69.

Next, in step 120, step 100
Then, it is determined whether or not the currently read satellite name has changed from the previously read satellite name. If the satellite name has not changed, the process proceeds to step 130. In step 130, it is determined whether or not the currently selected channel in step 110 has changed from the previously read channel.
If the selected channel has not changed, repeat step 10
Move to 0.

On the other hand, if it is determined in step 120 that the satellite name has changed, or if it is determined in step 130 that the selected channel has changed, step 14 is executed.
Move to 0. Then, in step 140, the station name and the local oscillation frequency corresponding to the selected channel are read from the channel selection data shown in FIG. In subsequent steps 150 and 160, attenuation amounts A and B corresponding to the read satellite name and selected channel are used.
Is read from the channel selection data shown in FIG. 5 (however, if the initial value of the attenuation A or B has been updated in the initial value changing process, the updated data).

Next, at steps 170, 180 and 190, the local oscillation frequency of the local oscillation circuit 13 is calculated.
The attenuation amount A of the first variable attenuation circuit 23 and the attenuation amount B of the second variable attenuation circuit 31 are respectively represented by the local oscillation frequency read in steps 140, 150 and 160, and
In order to set the attenuation amount A and the attenuation amount B, each of these circuits 1
The control signal is output to 3, 23, and 31, and step 10 is executed again.
Move to 0.

Next, FIG. 7 shows an initial value which is executed when the remote controller transmitting section 69 is operated to input a satellite name, a channel selection, an operation mode, and a deviation as a command for changing the amount of attenuation to the control circuit 50. It is a flowchart showing a change process. The remote controller transmitting section 69 includes, as operation modes, a demodulation bandwidth setting mode, which is a mode for changing the attenuation amount A of the first variable attenuation circuit 23 for determining the demodulation bandwidth in the FM demodulation circuit 25, and a video signal processing circuit 29.
And a video output level setting mode, which is a mode for changing the amount of attenuation B of the second variable attenuating circuit 31 that determines the level of the video signal output from the CPU. Wide, medium, and narrow frequency deviations, such as wide when the frequency deviation is wide, narrow when the frequency deviation is narrow, mid when the frequency deviation is intermediate, and so on. Three types of wide, mid and narrow can be entered.

As shown in FIG. 7, when the initial value changing process is started, first, at step 200, the input satellite name and channel selection channel are read. Then step 210
Then, it is determined whether or not the input operation mode is the demodulation bandwidth setting mode. If the operation mode is not the demodulation bandwidth setting mode, the process proceeds to the next step 270, where the operation mode is the demodulation bandwidth setting mode. If so, it is determined that the attenuation to be changed is the attenuation A of the first variable attenuation circuit 23, and the process proceeds to step 220.

In step 220, it is determined whether or not the input deviation is wide. If the deviation is wide, the flow shifts to step 230, where the satellite name and the selected channel read in step 200 are used. After setting the value of the corresponding attenuation amount A to 0 [dB], the process proceeds to step 270.

On the other hand, if it is determined in step 220 that the input deviation is not wide, the flow shifts to step 240 to determine whether or not the input deviation is mid. If it is determined in step 240 that the deviation is mid, the process proceeds to step 250, where the value of the attenuation A corresponding to the satellite name and the selected channel read in step 200 is set to α [dB]. Then, the process proceeds to step 270. Conversely, if it is determined that the deviation is not mid (ie, if the deviation is narrow),
In step 260, the value of the attenuation amount A corresponding to the satellite name and the selected channel read in step 200 is set to β [dB], and then the process proceeds to step 270.

Next, at step 270, it is determined whether or not the input operation mode is a video output level setting mode. If the operation mode is not the video output level setting mode, the process is terminated. If the operation mode is the video output level setting mode, the attenuation to be changed is the attenuation B of the second variable attenuation circuit 31. If it is determined that there is, the process proceeds to step 280.

In step 280, it is determined whether or not the input deviation is wide. If the deviation is wide, the flow shifts to step 290, where the value of the attenuation B corresponding to the satellite name and the selected channel read in step 200 is set to 11.3 [dB]. finish.

On the other hand, if it is determined in step 280 that the input deviation is not wide,
The process proceeds to step 300, where it is determined whether the input deviation is mid. And step 3
At 00, when it is determined that the deviation is mid, the process proceeds to the next step 310, where the value of the attenuation B corresponding to the satellite name and the selected channel read at step 200 is set to 9.8 [dB]. After the setting, the process is terminated. Conversely, if it is determined in step 300 that the deviation is not mid (that is, if the deviation is narrow), the process proceeds to step 320 and proceeds to step 200. After the value of the attenuation amount B corresponding to the read satellite name and the selected channel is set to 9.1 [dB], the process ends.

As described above, in the satellite signal receiving apparatus 1 of this embodiment, the first variable attenuating circuit 23 capable of changing the demodulation bandwidth of the FM demodulation circuit 25 in three stages and the video signal processing circuit 29 A second variable attenuating circuit 31 capable of changing the level of the demodulated signal to be input in three stages, and at the time of channel selection, the attenuation amount A of each of these variable attenuating circuits 23, 31 in accordance with the satellite and channel to be selected. , B are automatically controlled to an attenuation amount set in advance corresponding to the frequency shift of the radio wave. Therefore, according to the satellite signal receiving apparatus 1 of this embodiment, the demodulation bandwidth of the FM demodulation circuit 25 can be optimally controlled according to the frequency shift of the radio wave for each channel of each satellite, and the frequency shift of the radio wave can be controlled. Even if the demodulated signal level from the FM demodulation circuit 25 changes in accordance with the shift, the demodulated signal of a constant level is input to the video signal amplifying circuit 33, and the video signal level output from the video output terminal 30b to the external device is output. Can be controlled to be constant, and if a television receiver is connected to the satellite signal receiving apparatus 1, a stable and good image can always be obtained.

Further, in this embodiment, by inputting a command to change the attenuation amounts A and B of the respective variable attenuating circuits 23.31 through the remote controller transmitter 69, the respective variable attenuating circuits 23 and 3 are input.
One attenuation amount A, B can be changed for each satellite and each channel. For this reason, even if the initial values of the attenuation amounts A and B of the variable attenuation circuits 23 and 31 do not correspond to the actual values due to a change in the output characteristic of the transmission radio wave from the satellite or the reception characteristic of the receiving facility, etc. By changing the value, a good image can always be obtained.

In the above embodiment, the video signal processing circuit 2
In FIG. 9, the second variable attenuation circuit 31 is provided on the input side of the video signal amplification circuit 33, but the second variable attenuation circuit 31 may be provided on the output side of the video signal amplification circuit 33.

[0040]

As described above in detail, in the satellite signal receiving apparatus according to the present invention, the satellite signal specified from the outside by the channel selection circuit.
Convert star / channel TV signals to intermediate frequency signals
Amplifier circuit to increase the intermediate frequency signal to a certain level.
Through the first variable attenuation circuit.
By inputting to the FM demodulation circuit, the FM demodulation circuit
The intermediate frequency signal is demodulated, and the demodulated video signal is further demodulated.
Signal path (input side or output side of the video signal amplification circuit)
A second variable attenuation circuit is provided, and the first and second variable attenuation circuits are provided.
Attenuation amount storage means and attenuation amount adjustment
Means of the satellite / channel selected by the channel selection circuit.
Large frequency deviation corresponding to the frequency deviation of the Levi signal
The smaller the attenuation of the first variable attenuation circuit is, the smaller the second variable attenuation is.
As the attenuation of the attenuation circuit increases and the frequency shift decreases,
The amount of attenuation of the first variable attenuation circuit is large and the second variable attenuation circuit
Automatically adjust to reduce road attenuation.
Have been. Therefore, according to the satellite signal receiving apparatus of the present invention,
For example, for each satellite / channel selected by the tuning circuit,
According to the frequency shift of the transmission wave of the selected TV signal
To optimally control the demodulation bandwidth of the FM demodulation circuit.
The demodulated signal from the tuning circuit is converted to a signal with a high S / N ratio without noise.
And FM demodulation circuit of PLL system
Even if the demodulated signal level from
Signal level of the video signal
You. Therefore, according to the present invention, this video signal is transmitted to a television receiver.
Clear image without noise by input to image machine
Can be reproduced at a constant brightness.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a satellite signal receiving device 1 according to an embodiment.

2 is a diagram illustrating a demodulation bandwidth characteristic of an FM demodulation circuit 25. FIG.

FIG. 3 is an electric circuit diagram illustrating a configuration of a first variable attenuation circuit 23.

FIG. 4 is an electric circuit diagram illustrating a configuration of a second variable attenuation circuit 31.

FIG. 5 is an explanatory diagram showing tuning data stored in a ROM 53 in advance.

FIG. 6 is a flowchart illustrating a tuning process performed by the control circuit 50.

FIG. 7 is a flowchart showing an initial value changing process executed by the control circuit 50.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Satellite signal receiving device 3 ... Receiving antenna 11 ...
Tuning circuit 13 Local oscillation circuit 15 Frequency conversion circuit 21
... Amplifier circuit 23 ... First variable attenuation circuit 25 ... FM demodulation circuit 2
9: video signal processing circuit 31: second variable attenuation circuit 33: video signal amplifier circuit
50 control circuit 53 ROM 67 remote control receiver 69 remote control transmitter

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-147893 (JP, A) JP-A-2-27890 (JP, A) JP-A-63-23880 (JP, U)

Claims (1)

(57) [Claims] An output signal from one or a plurality of receiving antennas for receiving transmission radio waves from a plurality of artificial satellites, and a predetermined satellite and a predetermined channel corresponding to an external channel selection command from the signals. increasing a channel selection circuit for converting the intermediate frequency signal by selecting the television signal, the intermediate frequency signal from該選station circuit at a constant level of the signal
Amplifying circuit with built-in AGC circuit that widens , and PLL type FM that demodulates the amplified intermediate frequency signal
A satellite signal receiving device comprising: a demodulation circuit; and a video signal amplifying circuit for amplifying a video signal included in a demodulated signal from the FM demodulation circuit. An attenuating circuit, a second variable attenuating circuit provided on an input side or an output side of the video signal amplifying circuit, and a transmitting radio wave from a satellite for each satellite / channel for which the channel selecting circuit selects a channel. In response to the frequency shift , the transmission
As the frequency shift of the transmission radio wave is larger, the first variable attenuation
The attenuation of the road is small and the attenuation of the second variable attenuation circuit is small.
And the smaller the frequency deviation of the transmitted radio wave,
The amount of attenuation of the first variable attenuation circuit is large, and the amount of attenuation of the second variable attenuation circuit is large.
Attenuation amount storage means for storing the attenuation amounts of the first and second variable attenuation circuits set in advance so that the attenuation amount of the attenuation circuit is reduced; and a satellite and a channel on which the channel selection circuit selects a channel. Attenuation adjustment for reading the attenuation of the first and second variable attenuation circuits corresponding to the above from the attenuation storage means, and adjusting the attenuation of the first and second variable attenuation circuits to the read attenuation. Means, and a satellite signal receiving apparatus provided with: