Telecommunications – Wireless distribution system – Receiver for satellite broadcast
Reexamination Certificate
2000-01-19
2003-07-29
Nguyen, Lee (Department: 2682)
Telecommunications
Wireless distribution system
Receiver for satellite broadcast
C725S071000, C725S068000
Reexamination Certificate
active
06600897
ABSTRACT:
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
Suzuki Shigetaka
Watanabe Hirokazu
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Nguyen Lee
Persino Raymond
LandOfFree
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