Information
-
Patent Grant
-
6600897
-
Patent Number
6,600,897
-
Date Filed
Wednesday, January 19, 200024 years ago
-
Date Issued
Tuesday, July 29, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Nguyen; Lee
- Persino; Raymond
Agents
- Brinks Hofer Gilson & Lione
-
CPC
-
US Classifications
Field of Search
US
- 455 302
- 455 131
- 455 132
- 348 725
- 348 731
- 725 68
- 725 69
- 725 70
- 725 71
-
International Classifications
-
Abstract
A satellite-broadcasting receiving converter includes a plurality of output terminals each of which is connected to an external receiver, to each of which a selection control voltage in which a high-frequency voltage is superposed on a DC voltage is sent from the external receiver, and from each of which one type of a receiving signal is selected according to the selection control voltage and output; and a regulator for generating a power-source voltage from the selection control voltage. Since a high-frequency attenuation unit is connected in series between each output terminal and the regulator in the satellite-broadcasting receiving converter, even if a plurality of selection control voltages are input in common to the regulator, the plurality of selection control voltages different from each other do not affect each other and thereby only one regulator is required.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to satellite-broadcasting receiving converters with a plurality of output terminals, connected to satellite-TV-broadcasting receivers (hereinafter just called receivers).
2. Description of the Related Art
Satellite TV broadcasting uses, for example, a frequency band ranging from 10.7 GHz to 12.75 GHz, with 10.7 GHz to 11.7 GHz for analog broadcasting and 11.7 GHz to 12.75 GHz for digital broadcasting. A horizontal-polarization wave and a vertical-polarization wave are used for both analog broadcasting and digital broadcasting. In other words, four types of satellite TV broadcasting are used in combinations of analog broadcasting and digital broadcasting, and a horizontal-polarization wave and a vertical-polarization wave.
Satellite-broadcasting receiving converters receive satellite TV broadcasting signals sent from broadcasting satellites and convert a received frequency to a lower frequency.
When a satellite-broadcasting receiving antenna (not shown) receives a signal, the signal is divided into a horizontal-polarization wave and a vertical-polarization wave by a waveguide (not shown) and input to a satellite-broadcasting receiving converter.
FIG. 2
shows a conventional satellite-broadcasting receiving converter. The conventional satellite-broadcasting receiving converter includes a received-signal amplifier circuit section
51
for separately amplifying a horizontal-polarization wave and a vertical-polarization wave, a demultiplexer circuit section
52
for demultiplexing each amplified received signal into two signals with a boundary frequency of 11.7 GHz, a filter section
53
for attenuating the image signal of each demultiplexed received signal, a frequency-conversion section
54
for converting the frequency of each received signal output from the filter section
53
, an amplifier circuit section
55
for amplifying each frequency-converted received signal, signal selection means
56
for selecting a received signal of one type from the received signals output from the amplifier circuit section
55
, and two regulators
57
and
58
for supplying power-source voltages to the received-signal amplifier circuit section
51
to the signal selection means
56
.
The received-signal amplifier circuit section
51
has two amplifiers
59
and
60
. The horizontal-polarization wave is input to the amplifier
59
through an input end
51
a
and is amplified, and the vertical-polarization wave is input to the amplifier
60
through an input end
51
b
and is amplified.
The demultiplexer circuit section
52
has two demultiplexers
61
and
62
, and demultiplexes the polarized waves amplified by the received-signal amplifier circuit section
51
into analog received signals A
1
and A
2
having a frequency of 11.7 GHz or less and digital received signals D
1
and D
2
having a frequency of 11.7 GHz or more. With this demultiplexing, the received signals are demultiplexed into the four received signals and output from the demultiplexer circuit section
52
.
The filter section
53
has four band-elimination filters (BEFs)
63
to
66
. The received signals A
1
, A
2
, D
1
, and D
2
output from the demultiplexer circuit section
52
are input to the BEFs
63
to
66
, respectively.
Among these BEFs, the BEFs
63
and
64
attenuate signals having frequencies of 7.8 GHz to 8.8 GHz, which correspond to the frequency band of the image signals of the analog received signals A
1
and A
2
, and the BEFs
65
and
66
attenuate signals having frequencies of 8.45 GHz to 9.5 GHz, which correspond to the frequency band of the image signals of the digital received signals D
1
and D
2
.
The received signals whose image signals are attenuated by the BEFs
63
to
66
are input to the frequency converter section
54
.
The frequency converter section
54
has four mixers
67
to
70
and two oscillators
71
and
72
. The received signals A
1
, A
2
, D
1
, and D
2
are input to the mixers
67
to
70
provided correspondingly to the BEFs
63
to
66
, respectively.
The oscillator
71
inputs an oscillation signal having a frequency of 9.75 GHz into the mixers
67
and
68
, and the oscillator
72
inputs an oscillation signal having a frequency of 10.6 GHz into the mixers
69
and
70
. The frequencies of the analog received signals A
1
and A
2
input into the mixers
67
and
68
are converted to those in a range from 950 MHz to 1950 MHz, and the frequencies of the digital received signals D
1
and D
2
input into the mixers
69
and
70
are converted to those in a range from 1100 MHz to 2150 MHz. The frequency-converted received signals a
1
, a
2
, d
1
, and d
2
are input to the amplifier circuit section
55
.
The amplifier circuit section
55
has four amplifiers
73
to
76
. The frequency-converted received signals a
1
, a
2
, d
1
, and d
2
are input to the amplifiers
73
to
76
provided correspondingly to the mixers
67
to
70
, respectively. The received signals amplified by the amplifiers
73
to
76
are input to the signal selection means
56
.
The signal selection means
56
has a signal switching circuit
77
, two switching control circuits
78
and
79
, and two output terminals
56
a
and
56
b
. The signal switching circuit
77
selects one of the outputs of the amplifiers
73
to
76
according to the control of the switching control circuit
78
and connects it to one terminal
56
a
, and selects one of the outputs of the amplifiers
73
to
76
according to the control of the switching control circuit
79
and connects it to the other output terminal
56
b.
The output terminals
56
a
and
56
b
are connected to different receivers (not shown). Each receiver sends a selection control voltage used for operating each circuit section of the satellite-broadcasting receiving converter and for controlling the signal selection means
56
. This selection control voltage is set to a first DC voltage of, for example, 18 V to select a horizontal-polarization wave, and is set to a second DC voltage of, for example, 14 V to select a vertical-polarization wave. To select a digital received signal d
1
or d
2
, a 22-kHz high-frequency voltage is superposed on the corresponding DC voltage.
More specifically, to select the horizontal-polarization analog broadcasting signal a
1
, the first DC voltage is sent; to select the vertical-polarization analog broadcasting signal a
2
, the second DC voltage is sent; to select the horizontal-polarization digital broadcasting signal d
1
, the first DC voltage on which the high-frequency voltage is superposed is sent; and to select the vertical-polarization digital broadcasting signal d
2
, the second DC voltage on which the high-frequency voltage is superposed is sent to the corresponding output terminal
56
a
or
56
b
as a selection control signal.
A selection control voltage sent to the output terminal
56
a
is input to the switching control circuit
78
and the regulator
57
through a high-frequency choke coil
80
. In the same way, a selection control voltage sent to the output terminal
56
b
is input to the switching control circuit
79
and the regulator
58
through a high-frequency choke coil
81
.
The regulators
57
and
58
supply a power-source voltage of, for example, 8 V to the circuit sections
51
to
56
. These two regulators
57
and
58
have the same structure and each have a voltage stabilizer circuit formed of an integrated circuit. The output ends of the regulators
57
and
58
are connected to a power-source-voltage output terminal
84
through reverse-current-prevention diodes
82
and
83
, respectively. Therefore, even if one receiver is stopped, this satellite-broadcasting receiving converter is ready to operate since the power-source voltage is supplied to the circuit sections
51
to
56
. Since the two regulators
57
and
58
are connected in series between the two output terminals
56
a
and
56
b
, the switching control circuits
78
and
79
operate only by the switching control voltage sent from one of the output terminals
56
a
and
56
b.
As described above, since the conventional satellite-broadcasting receiving converter is provided with the two regulators
57
and
58
so as to be ready to operate even if one of two receivers connected to the two output terminals
56
a
and
56
b
is stopped, the converter is expensive.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an inexpensive satellite-broadcasting receiving converter.
The foregoing object is achieved according to the present invention through the provision of a satellite-broadcasting receiving converter including a plurality of output terminals each of which can be connected to an external receiver, to each of which any one of four types of selection control voltages specified according to the combinations of high and low DC voltages and whether a high-frequency voltage having a predetermined frequency is superposed is separately sent from the external receiver, and from each of which a satellite-broadcasting receiving signal of a type selected according to the selection control voltage is separately output to the external receiver; signal selection means for selecting one type of a receiving signal according to the selection control voltage from four types of satellite-broadcasting receiving signals different in modulation-signal form and polarization direction from each other for each output terminal to output it; a regulator for receiving the selection control voltage sent from each output terminal in common and for converting the selection control voltage to a predetermined power-source voltage to output it; and a plurality of high-frequency attenuation means each connected in series between each output terminal and an input end of the regulator.
Since each of the high-frequency attenuation means is connected in series between each output terminal and the input end of the regulator, the selection control voltage sent to each output terminal reaches the input end of the regulator with its superposed high-frequency voltage being sufficiently attenuated by the high-frequency attenuation means. The selection control voltage does not flow reversely into other output terminals from the input end of the regulator. A type of a receiving signal is separately selected and output to each output terminal. Therefore, only one regulator is required for a plurality of types of selection control voltages sent from a plurality of output terminals.
The satellite-broadcasting receiving converter may be configured such that each of the plurality of high-frequency attenuation means includes a transistor and a low-pass filter having a cutoff frequency lower than the frequency of the high-frequency voltage.
In this case, the high-frequency voltage is attenuated by a simple circuit.
The satellite-broadcasting receiving converter may be configured such that the low-pass filter is formed of a resistor and a capacitor which determine the cutoff frequency; and the selection control voltage is input to the collector of the transistor, the resistor is connected between the collector and the base, the base is grounded through the capacitor, and the emitter is connected to the input end of the regulator.
In this case, a ripple-voltage attenuation effect is great and the signal selection means is positively operated with its erroneous operation being prevented.
Alternatively, the satellite-broadcasting receiving converter may be configured such that a high-frequency choke coil and a reverse-current-prevention diode are connected to each other in series between the output terminal and the collector of the transistor.
In this case, even if a high reverse voltage is applied to the high-frequency attenuation means, the transistor is not destroyed by the reverse voltage.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a circuit diagram of a satellite-broadcasting receiving converter according to an embodiment of the present invention.
FIG. 2
is a circuit diagram of a conventional satellite-broadcasting receiving converter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A satellite-broadcasting receiving converter according to an embodiment of the present invention will be described below by referring to FIG.
1
. The satellite-broadcasting receiving converter includes a received-signal amplifier circuit section
1
for separately amplifying a horizontal-polarization wave and a vertical-polarization wave, a demultiplexer circuit section
2
for demultiplexing each amplified received signal into two signals with a boundary frequency of 11.7 GHz, a filter section
3
for attenuating the image signal of each demultiplexed received signal, a frequency-conversion section
4
for converting the frequency of each received signal output from the filter section
3
, an amplifier circuit section
5
for amplifying each frequency-converted received signal, signal selection means
6
for selecting a received signal of one type from the received signals output from the amplifier circuit section
5
, a regulator
7
for supplying a power-source voltage to the received-signal amplifier circuit section
1
to the signal selection means
6
, and two high-frequency attenuating means
8
and
9
.
The received-signal amplifier circuit section
1
has two amplifiers
10
and
11
. The horizontal-polarization wave is input to the amplifier
10
through an input end la and is amplified, and the vertical-polarization wave is input to the amplifier
11
through an input end lb and is amplified.
The demultiplexer circuit section
2
has two demultiplexers
12
and
13
, and demultiplexes the polarized waves amplified by the received-signal amplifier circuit section
1
into analog received signals A
1
and A
2
having a frequency of 11.7 GHz or less and digital received signals D
1
and D
2
having a frequency of 11.7 GHz or more. With this demultiplexing, the received signals are demultiplexed into the four received signals and output from the demultiplexer circuit section
2
.
The filter section
3
has four band-elimination filters (BEFs)
14
to
17
. The received signals A
1
, A
2
, D
1
, and D
2
output from the demultiplexer circuit section
2
are input to the BEFs
14
to
17
, respectively.
Among these BEFs, the BEFs
14
and
15
attenuate signals having frequencies of 7.8 GHz to 8.8 GHz, which correspond to the frequency band of the image signals of the analog received signals A
1
and A
2
, and the BEFs
16
and
17
attenuate signals having frequencies of 8.45 GHz to 9.5 GHz, which correspond to the frequency band of the image signals of the digital received signals D
1
and D
2
.
The received signals whose image signals are attenuated by the BEFs
14
to
17
are input to the frequency converter section
4
.
The frequency converter section
4
has four mixers
18
to
21
and two oscillators
22
and
23
. The received signals A
1
, A
2
, D
1
, and D
2
are input to the mixers
18
to
21
provided correspondingly to the BEFs
14
to
17
, respectively.
The oscillator
22
inputs an oscillation signal having a frequency of 9.75 GHz into the mixers
18
and
19
, and the oscillator
23
inputs an oscillation signal having a frequency of 10.6 GHz into the mixers
20
and
21
. The frequencies of the analog received signals A
1
and A
2
input into the mixers
18
and
19
are converted to those in a range from 950 MHz to 1950 MHz, and the frequencies of the digital received signals D
1
and D
2
input into the mixers
20
and
21
are converted to those in a range from 1100 MHz to 2150 MHz. The frequency-converted received signals a
1
, a
2
, d
1
, and d
2
are input to the amplifier circuit section
5
.
The amplifier circuit section
5
has four amplifiers
24
to
27
. The frequency-converted received signals a
1
, a
2
, d
1
, and d
2
are input to the amplifiers
24
to
27
provided correspondingly to the mixers
18
to
21
, respectively. The received signals amplified by the amplifiers
24
to
27
are input to the signal selection means
6
.
The signal selection means
6
has a signal switching circuit
28
, two switching control circuits
29
and
30
, and two output terminals
6
a
and
6
b
. The signal switching circuit
28
selects one of the outputs of the amplifiers
24
to
27
according to the control of the switching control circuit
29
and connects it to one terminal
6
a
, and selects one of the outputs of the amplifiers
24
to
27
according to the control of the switching control circuit
30
and connects it to the other output terminal
6
b.
The output terminals
6
a
and
6
b
are connected to different receivers (not shown). Each receiver sends a selection control voltage used for operating each circuit section of the satellite-broadcasting receiving converter and for controlling the signal selection means
6
. This selection control voltage is set to a first DC voltage of, for example, 18 V to select a horizontal-polarization wave, and is set to a second DC voltage of, for example, 14 V to select a vertical-polarization wave. To select a digital received signal d
1
or d
2
, a 22-kHz high-frequency voltage is superposed on the corresponding DC voltage.
More specifically, to select the horizontal-polarization analog received signal a
1
, the first DC voltage is sent; to select the vertical-polarization analog received signal a
2
, the second DC voltage is sent; to select the horizontal-polarization digital received signal d
1
, the first DC voltage on which the high-frequency voltage is superposed is sent; and to select the vertical-polarization digital broadcasting signal d
2
, the second DC voltage on which the high-frequency voltage is superposed is sent to the corresponding output terminal
6
a
or
6
b
as a selection control signal.
A selection control voltage sent to the output terminal
6
a
is input to the switching control circuit
29
through a high-frequency choke coil
31
and to the high-frequency attenuation means
8
through a reverse-current-prevention diode
33
. In the same way, a selection control voltage sent to the output terminal
6
b
is input to the switching control circuit
30
through a high-frequency choke coil
32
and to the high-frequency attenuation means
9
through a reverse-current-prevention diode
34
.
The high-frequency attenuation means
8
includes a transistor
36
and a low-pass filter
42
formed of a resistor
37
connected between the collector and the base of the transistor
36
and a capacitor
38
connected between the base of the transistor
36
and the ground. The collector of the transistor
36
, serving as an input end of the high-frequency attenuation means
8
, is connected to the cathode of the diode
33
, and the emitter of the transistor
36
, serving as an output end of the high-frequency attenuation means
8
, is connected to an input end of the regulator
7
. The high-frequency attenuation means
9
has the same structure as the high-frequency attenuation means
8
. The high-frequency attenuation means
9
includes a transistor
39
and a low-pass filter
43
formed of a resistor
40
and a capacitor
41
. The collector of the transistor
39
is connected to the cathode of the diode
34
, and the emitter of the transistor
39
is connected to the input end of the regulator
7
.
The cutoff frequency of the low-pass filter
42
is specified by the resistor
37
and the capacitor
38
. The cutoff frequency of the low-pass filter
43
is specified by the resistor
40
and the capacitor
41
. Both cutoff frequencies are set so as to be lower than the frequency of the high-frequency voltage included in a selection control voltage.
Since the cutoff frequencies of the low-pass filters
42
and
43
are set so as to be lower than the frequency of the high-frequency voltage as described above, a selection control voltage input to one output terminal
6
a
is sent to the input end of the regulator
7
with the superposed high-frequency voltage being attenuated to a level which practically has no problem by the high-frequency choke coil
31
and the high-frequency attenuation means
8
, and is blocked by the other high-frequency attenuation means
9
and thereby is not input to the other switching control circuit
30
. Since the high-frequency attenuation means
8
and
9
are formed of combinations of the transistors
36
and
39
and the low-pass filters
42
and
43
, even if the capacitances of the capacitors
38
and
41
in the low-pass filters
42
and
43
are low, a high ripple attenuation effect is obtained.
The regulator
7
has a voltage stabilizer circuit formed of an integrated circuit. Selection control voltages input to both output terminals
6
a
and
6
b
are input into the regulator
7
in common through the high-frequency attenuation means
8
and
9
. In other words, when at least one receiver is operating, a DC voltage of 18 V or 14 V is input to the regulator
7
, and the regulator
7
converts the input DC voltage, for example, to a DC voltage of 8V, outputs it from a power-source-voltage output terminal
35
, and sends it as a power-source voltage to the circuit sections
1
to
6
of the satellite-broadcasting receiving converter.
In the above embodiment, the satellite-broadcasting receiving converter is provided with a plurality of output terminals, namely, the two output terminals
6
a
and
6
b
. A satellite-broadcasting receiving converter according to the present invention may be provided with three or more output terminals. The attenuation means
8
and
9
are formed of the transistors and the low-pass filters in the above embodiment. Each attenuation means may include an LC low-pass filter formed of an inductor and a capacitor. In this case, the same advantage is obtained.
Claims
- 1. A satellite-broadcasting receiving converter comprising:a plurality of output terminals each of which can be connected to an external receiver, to each of which any one of four types of selection control voltages specified according to the combinations of high and low DC voltages and whether a high-frequency voltage having a predetermined frequency is superposed is separately sent from the external receiver, and from each of which a satellite-broadcasting receiving signal of a type selected according to the selection control voltage is separately output to the external receiver; signal selection means for selecting one type of a receiving signal according to the selection control voltage from four types of satellite-broadcasting receiving signals different in modulation-signal form and polarization direction from each other for each output terminal to output it; a regulator for receiving the selection control voltage sent from each output terminal in common and for converting the selection control voltage to a predetermined power-source voltage to output it; and a plurality of high-frequency attenuation means each connected in series between each output terminal and an input end of said regulator.
- 2. A satellite-broadcasting receiving converter according to claim 1, wherein each of said plurality of high-frequency attenuation means comprises a transistor and a low-pass filter having a cutoff frequency lower than the frequency of the high-frequency voltage.
- 3. A satellite-broadcasting receiving converter according to claim 2,wherein the low-pass filter is formed of a resistor and a capacitor which determine the cutoff frequency; and the selection control voltage is input to the collector of the transistor, the resistor is connected between the collector and the base, the base is grounded through the capacitor, and the emitter is connected to the input end of the regulator.
- 4. A satellite-broadcasting receiving converter according to claim 2, wherein a high-frequency choke coil and a reverse-current-prevention diode are connected to each other in series between the output terminal and the collector of the transistor.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 11-019126 |
Jan 1999 |
JP |
|
US Referenced Citations (14)
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| 5-46147 |
Jun 1993 |
JP |
| 7-50607 |
Feb 1995 |
JP |
