Telecommunications – Wireless distribution system – Receiver for satellite broadcast
Reexamination Certificate
2000-03-02
2004-07-13
Corsaro, Nick (Department: 2684)
Telecommunications
Wireless distribution system
Receiver for satellite broadcast
C455S430000, C455S013300, C342S362000
Reexamination Certificate
active
06763223
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a low noise converting apparatus suitable for use in a case where, for example, radio waves from a plurality of satellites are received by one parabolic antenna.
2. Description of the Related Art
A satellite broadcasting receiving system is provided with a low noise converter (referred to as an LNB) for converting a signal of a band of, for example, 12 GHz received by a parabolic antenna to an intermediate frequency signal of a band of, for example, 1 GHz and transmitting the signal to an indoor IRD (Integrated Receiver Decoder) or a receiver such as television receiver, VTR, or the like having a receiving tuner of a satellite broadcasting through a connecting cable.
FIG. 1
shows an example of such a conventional low noise converter.
In
FIG. 1
, reference numerals
111
and
112
denote current feeding devices. Radio waves are transmitted from a satellite existing on a geostationary satellite orbit by using a band of, for example, 12 GHz by radio waves having an orthogonal relation, for example, by a horizontally polarized wave and a vertically polarized wave. The radio waves from the satellite are received by a parabolic antenna. The reception signals are inputted to the current feeding devices
111
and
112
. The reception signals of the horizontally polarized wave and vertically polarized wave are obtained from the current feeding devices
111
and
112
, respectively.
The reception signal of the horizontally polarized wave from the current feeding device
111
is supplied to a low noise amplifier
121
. The reception signal of the vertically polarized wave from the current feeding device
112
is supplied to a low noise amplifier
122
and amplified.
Control signals are supplied to the low noise amplifiers
121
and
122
from a control unit
110
. Although not shown, a switching signal of the horizontally polarized wave and vertically polarized wave is supplied to the control unit
110
from a satellite tuner. A control is performed so that either the low noise amplifier
121
or
122
is made operative in response to the switching signal. Thus, the switching between the horizontally polarized wave and vertically polarized wave is performed.
An output of the low noise amplifier
121
or
122
is supplied to a low noise amplifier
104
through a coupling circuit
103
. The reception signal is further amplified by the low noise amplifier
104
. An output of the low noise amplifier
104
is supplied to a filter circuit
105
. Unnecessary band components in the reception signal are removed by the filter circuit
105
. An output of the filter circuit
105
is supplied to a mixer
106
.
A local oscillating signal from a local oscillator
107
is supplied to the mixer
106
. In the mixer
106
, the reception signal of a band of, for example, 12 GHz is converted to an intermediate frequency signal of a band of, for example, 1 GHz. An output of the mixer
106
is extracted from an output terminal
109
through a high frequency amplifier
108
. A signal from the output terminal
109
is supplied to the indoor receiver through a connecting cable.
The conventional low noise converter shown in
FIG. 1
receives the signal transmitted from one satellite on the geostationary satellite orbit. The radio waves are transmitted from the satellite by two planes of polarization of the horizontally polarized wave and vertically polarized wave. Therefore, the low noise amplifier
121
for the horizontally polarized wave and the low noise amplifier
122
for the vertically polarized wave are provided for the low noise converter. The switching between the horizontally polarized wave and vertically polarized wave is performed by selectively making the low noise amplifier
121
for the horizontally polarized wave and the low noise amplifier
122
for the vertically polarized wave operative.
In recent years, in association with the development of broadcasting services, a number of satellites were launched. Among the satellites, there are satellites launched to close positions on the geostationary satellite orbit. Signals transmitted from the two satellites launched to close positions on the geostationary satellite orbit as mentioned above can be received by one antenna.
FIG. 2
shows a construction of a conventional low noise converter in the case where the signals from the two satellites existing at close positions on the geostationary satellite orbit are received by one antenna.
In
FIG. 2
, reference numerals
211
and
212
denote current feeding devices for a reception signal from one satellite and
213
and
214
indicate current feeding devices for a reception signal from the other satellite. The radio waves are transmitted from the two satellites existing at close positions on the geostationary satellite orbit by the horizontally polarized wave and vertically polarized wave by using a band of, for example, 12 GHz. The radio waves from the two satellites are received by one parabolic antenna.
Between the two reception outputs, the signal from one satellite is inputted to the current feeding devices
211
and
212
and the reception signals of the horizontally polarized wave and vertically polarized wave of one satellite are derived from the current feeding devices
211
and
212
, respectively. The signal from the other satellite is inputted to the current feeding devices
213
and
214
and the reception signals of the horizontally polarized wave and vertically polarized wave of one satellite are derived from the current feeding devices
213
and
214
, respectively.
The reception signal of the horizontally polarized wave of one satellite which is supplied from the current feeding device
211
is sent to a low noise amplifier
221
and amplified. The reception signal of the vertically polarized wave of one satellite which is supplied from the current feeding device
212
is sent to a low noise amplifier
222
and amplified. Control signals are supplied from a control unit
230
to the low noise amplifiers
221
and
222
. A switching signal of the horizontally polarized wave and vertically polarized wave is supplied to the control unit
230
. A control is performed so that either the low noise
20
amplifier
221
or
222
is made operative in response to the switching signal. Thus, the switching between the horizontally polarized wave and vertically polarized wave is performed.
An output of the low noise amplifier
221
or
25
222
is supplied to a low noise amplifier
241
through a coupling circuit
231
. The reception signal is further amplified by the low noise amplifier
241
. An output of the low noise amplifier
241
is supplied to a coupling circuit
233
.
The reception signal of the horizontally polarized wave of the other satellite which is supplied from the current feeding device
213
is sent to a low noise amplifier
223
and amplified. The reception signal of the vertically polarized wave of the other satellite which is supplied from the current feeding device
214
is sent to a low noise amplifier
224
and amplified. Control signals are supplied from the control unit
230
to the low noise amplifiers
223
and
224
. The switching signal of the horizontally polarized wave and vertically polarized wave is supplied to the control unit
230
. A control is performed so that either the low noise amplifier
223
or
224
is made operative in response to the switching signal. Thus, the switching between the horizontally polarized wave and vertically polarized wave is performed.
An output of the low noise amplifier
223
or
224
is supplied to a low noise amplifier
242
through a coupling circuit
232
. The reception signal is further amplified by the low noise amplifier
242
. An output of the low noise amplifier
242
is supplied to the coupling circuit
233
.
The control signals are supplied from the control unit
230
to the low noise amplifiers
241
and
242
. A switching signal of two satellites is supplied to the control unit
230
. A control is performed so that either the low noise amplifi
Hirabayashi Katsuki
Tanaka Masayuki
Corsaro Nick
Maioli Jay H.
Sony Corporation
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