Telecommunications – Wireless distribution system – Receiver for satellite broadcast
Reexamination Certificate
2000-09-18
2004-12-14
Corsaro, Nick (Department: 2684)
Telecommunications
Wireless distribution system
Receiver for satellite broadcast
C455S430000, C455S428000, C455S013300, C342S362000, C370S326000
Reexamination Certificate
active
06832071
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a satellite broadcast reception system. More particularly, the present invention relates to a satellite broadcast reception system that can receive individually with a plurality of satellite receivers a plurality of satellite broadcasting signals received from a plurality of satellites.
2. Description of the Background Art
Referring to
FIG. 8
, communication satellites (CS) called JCSAT
3
and JCSAT
4
are launched at 128° and 124° of east longitude up in the sky over Japan. The satellite broadcasting signal transmitted by respective satellites are formed of the two types of signals of a horizontally polarized wave and a vertically polarized wave. The antenna for receiving a satellite broadcast that can receive satellite broadcasting signals transmitted from the two satellites includes a reflector dish
6
reflecting the satellite broadcasting signal transmitted by the two satellites, and an LNB (Low Noise Block Down Converter)
58
that amplifies the low noise of a satellite broadcasting signal reflected at reflector dish
6
and converts the frequency down to a low frequency band. A receiver of a satellite broadcasting signal such as a television receiver
60
is connected to LNB
58
.
Referring to
FIG. 9
, a conventional LNB
58
includes an LNA (Low Noise Amplifier)
62
receiving horizontally and vertically polarized wave signals transmitted from JCSAT
3
and horizontally and vertically polarized wave signals transmitted from JCSAT
4
to amplify the low noise of either signal according to an output of a power supply circuit
68
that will be described afterwards, a BPF (Band Pass Filter)
64
connected to LNA
62
to receive the output of LNA
62
as an input, a local oscillator
26
generating a local oscillator signal of 11.2 GHz, a mixer
30
A connected to BPF
64
and local oscillator
26
to mix the local oscillator signal with the signal output from BPF
64
to provide an IF (Intermediate Frequency) signal, an IF amplifier
66
connected to the output of mixer
30
A to amplify an IF signal, and a capacitor
35
A connected to the output of IF amplifier
66
to cut the noise of low frequency. Capacitor
35
A is connected to the output terminal of an IF signal. The IF signal output terminal has the foregoing receiver connected to the end.
LNB
58
further includes a power supply circuit
68
connected to the IF signal output terminal to receive direct current DC from the IF signal output terminal and a low frequency pulse signal AC of an alternating current of several ten KHz overlying direct current DC to supply desired power to a semiconductor amplify element forming LNA
62
according to the voltage value of direct current DC and the presence of low frequency pulse signal AC. Power supply circuit
68
also supplies power to each component forming LNB
58
besides LNA
62
.
LNA
62
includes semiconductor amplify elements
63
A and
63
B receiving the horizontally polarized wave signal and vertically polarized wave signal transmitted from JCSAT
3
as respective inputs, semiconductor amplify elements
63
C and
63
D receiving the horizontally polarized wave signal and vertically polarized wave signal from JCSAT
4
as inputs, respectively, and a semiconductor amplify element
63
E connected to the outputs of semiconductor amplify elements
63
A-
63
D.
The voltage value of direct current DC supplied from the IF signal output terminal includes the two types of 18 V and 13 V. When the voltage value of direct current DC is 18 V, a horizontally polarized wave signal is selected. When the voltage value of direct current DC is 13 V, a vertically polarized wave signal is selected. In the case direct current DC is overlaid over low frequency pulse signal AC, JCSAT
3
is selected. When direct current DC is not overlaid over low frequency pulse signal AC, JCSAT
4
is selected.
For example, in the case where direct current DC of 13 V overlaid with low frequency pulse signal AC is supplied to power supply circuit
68
from a receiver connected to the IF signal output terminal, the receiver selects the vertically polarized wave signal transmitted from JCSAT
3
. Therefore, power supply circuit
68
supplies power to semiconductor amplify elements
63
B and
63
E forming LNA
62
. Power is not supplied to semiconductor amplify elements
63
A,
63
C and
63
D. Thus, the vertically polarized wave signal transmitted from JCSAT
3
has the low noise amplified by semiconductor amplify elements
63
B and
63
E. The low-noise amplified signal is applied to BPF
64
to have the image signal removed. Mixer
30
A mixes the local oscillator signal generated at local oscillator
63
with the signal output from BPF
64
to provide an IF signal. IF amplifier
66
amplifies the IF signal. The amplified IF signal has the noise of the low frequency cut at capacitor
35
A, and then output from the IF signal output terminal.
Accordingly, one of the two satellites is selected, and one of the two types of polarized wave signals transmitted from the selected satellite is selected. The selected polarized wave signal has the low noise amplified and frequency converted to be output from the IF signal output terminal.
LNB
58
has only one IF signal output terminal. Therefore, the signal output from LNB
58
is limited to one polarized wave signal transmitted from one satellite. This means that only one receiver can be connected to one LNB
58
. A plurality of television receivers or video recorders cannot be connected thereto.
The satellite is selected based on the presence of low frequency pulse signal AC. Therefore, one LNB
58
can only receive the satellite broadcasting signals from two satellites. It was difficult to receive satellite broadcasting signals from three or more satellites.
If a satellite can be selected by digital serial data instead of the presence of a low frequency pulse signal AC, information of what type of polarized wave signal from which satellite has been selected can be processed by providing an apparatus that can process digital data such as a personal computer at the receiver side.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a satellite broadcast reception system that can have a plurality of receivers connected.
Another object of the present invention is to provide a satellite broadcast reception system that can receive a satellite broadcasting signal from at least three satellites.
A further object of the present invention is to provide a satellite broadcast reception system that can process information related to selection of a satellite and a polarized wave signal.
A low noise block down converter according to an aspect of the present invention includes a conversion unit receiving a plurality of types of polarized wave signals transmitted from each of a plurality of satellites to convert a plurality of polarized wave signals into a plurality of intermediate frequency signals, an amplify switch connected to the conversion unit with a plurality of intermediate frequency signals as inputs, and having a plurality of outputs connected to a plurality of output ports, respectively to determine a status according to a select signal and providing an amplified intermediate frequency signal, and a first control unit receiving external digital serial data to select a satellite via an output port and providing a select signaled according to the digital serial data.
The plurality of types of polarized wave signals transmitted from respective plurality of satellites are converted into intermediate frequency signals and then applied to the amplify switch. The first control unit receives external digital serial data via the plurality of output ports to apply a select signal to the amplify switch. The amplify switch receives a select signal for each output to provide a polarized wave signal according to the select signal. Therefore, a plurality of polarized wave signals are output from one low noise block down converter. The plurality of polarized wave
Atarashi Hiroshi
Imai Takao
Nakamura Makio
Okahashi Tetsuhide
Wakiyama Masanori
Corsaro Nick
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
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