Interactive video distribution systems – Satellite video distribution system – Receiver
Reexamination Certificate
2000-05-04
2004-05-18
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Satellite video distribution system
Receiver
C725S070000, C725S073000, C375S316000, C326S086000, C326S093000
Reexamination Certificate
active
06738979
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a receiver and, more particularly, to a receiver for receiving a satellite broadcast (BS or CS broadcast), processing a received signal, converting the received signal to a CATV (cable television) signal, and outputting the CATV signal.
2. Related Art
Generally, a cable television system is constructed by CATV broadcast facilities disposed in the center and a number of CATV broadcast contracted receivers connected to the CATV broadcast facilities via RF transmission paths such as optical fibers or coaxial transmission paths. The CATV broadcast facilities provide various CATV broadcasts of a plurality of channels to each of the CATV broadcast contracted receivers via the RF transmission paths. On the other hand, the user of the contracted receiver selects a broadcast of a desired channel among the CATV broadcasts of the plurality of channels supplied from the CATV broadcast facilities and watches the selected broadcast by his/her contracted receiver.
The CATV broadcast facilities provide service of outputting a received satellite broadcast as a CATV broadcast to the RF transmission path. The service is received by an receiver comprising: a satellite broadcast tuner for receiving a satellite broadcast: a demodulating unit for demodulating an output signal of the satellite broadcast tuner and reproducing a baseband signal; a control unit for processing the demodulated baseband signal; a modulating unit for modulating the processed baseband signal and generating a modulated signal; and a CATV signal converting unit for converting the modulated signal into a CATV broadcast signal adapted to a CATV broadcast transmitted.
FIG. 4
is a block diagram showing an example of the configuration of a satellite broadcast signal—CATV broadcast signal converting mechanism, that is, a satellite broadcast receiver in known CATV broadcast facilities.
As shown in
FIG. 4
, the satellite broadcast receiver comprises: a BS broadcast receiving antenna
41
; a satellite broadcast tuner
42
which is a BS tuner; an IC (Integrated Circuit)
43
for demodulation including an I/Q demodulating unit
43
1
and a QPSK demodulating unit
43
2
; a control unit
44
for performing an MPEG process; an IC (Integrated Circuit)
45
for modulation including a QAM unit
45
1
; a CATV signal converting unit
46
; a digital-to-analog (D/A) converter
47
; and a CATV signal output terminal
48
.
The signal input terminal of the satellite broadcast tuner
42
is connected to the BS broadcast receiving antenna
41
and the signal output terminal is connected to the signal input terminal of the I/Q demodulating unit
43
1
The signal input terminal of the QPSK demodulating unit
43
2
is connected to the signal output terminal of the I/Q demodulating unit
43
1
, and the signal output terminal of the QPSK demodulating unit
43
2
is connected to the signal input terminal of the control unit
44
. The signal input terminal of the QAM unit
45
1
is connected to the signal output terminal of the control unit
44
, and the signal output terminal of the QAM unit
45
1
is connected to the signal input terminal of the CATV signal converting unit
46
. The signal output terminal of the CATV signal converting unit
46
is connected to the CATV signal output terminal
48
. The signal input and output terminals of the digital-to-analog converter
47
are connected to the control signal output terminal of the control unit
44
and a channel selection signal input terminal of the satellite broadcast tuner
42
via an I square C (I
2
C) bus
49
, respectively. An I
2
C bus
50
is connected between the control signal output terminal of the control unit
44
and the channel control terminal of the CATV signal converting unit
46
via the QAM unit
45
1
(IC
45
for modulation).
The satellite broadcast receiver having the above configuration operates as follows.
When a BS broadcast is received by the BS broadcast receiving antenna
41
, the received signal is amplified and frequency-converted (down-converted) by the satellite broadcast tuner
42
and is outputted as an intermediate frequency signal. The intermediate frequency signal is converted by the I/Q demodulating unit
43
1
into an I signal and a Q signal whose phases are different from each other by 90 degrees. The I and Q signals are converted to QPSK modulated signals by the QPSK demodulating unit
43
2
. The QPSK modulated signals are subjected to image compression by an MPEG process in the control unit
44
and the resultant signals are outputted as baseband signals. The baseband signals are subjected to quadrature amplitude modulation by the QAM unit
45
1
. A quadrature amplitude modulated signal is amplified and frequency-converted (up-converted) by the CATV signal converting unit
46
and a resultant signal is outputted as a radio-frequency (RF) CATV signal to an RF transmission path (not shown) via the CATV signal output terminal
48
.
In this case, a digital channel selection signal outputted from the control signal output terminal of the control unit
44
is supplied to the digital-to-analog converter
47
via the I
2
C bus
49
and is converted by the digital-to-analog converter
47
to an analog channel selection signal. The analog channel selection signal is supplied to a channel selection signal input terminal via the I
2
C bus
49
and the channel selection of the satellite broadcast tuner
42
is performed. A channel selection signal outputted from the control signal output terminal of the control unit
44
to the I
2
C bus
50
is supplied to the channel control terminal of the CATV signal converting unit
46
via the QAM unit
45
1
to select the channel of an RF signal outputted from the CATV signal converting unit
46
.
In the known satellite broadcast receiver, the control unit
44
, digital-to-analog converter
47
, and satellite broadcast tuner
42
are connected via the I
2
C bus
49
. Another known satellite broadcast receiver has a configuration such that the control unit
44
, IC
43
for demodulation, and satellite broadcast tuner
42
are connected via the I
2
C bus.
The known satellite broadcast receiver has the configuration such that the control unit
44
, digital-to-analog converting unit
47
, and satellite broadcast tuner
42
are connected to the I
2
C bus
49
for transmitting a channel selection signal from the control unit
44
to the satellite broadcast tuner
42
or the configuration such that the control unit
44
, IC
43
for demodulation, and satellite broadcast tuner
42
are connected to the I
2
C bus
49
. Consequently, when a serial clock (SCL) and serial data (SDA) is transmitted via the I
2
C bus between the control unit
44
and the digital-to-analog converting unit
47
or between the control unit
44
and the IC
43
for demodulation, the serial clock and serial data is transmitted also to the satellite broadcast tuner
42
via the I
2
C bus. When the serial clock and serial data is supplied to the channel selection signal input terminal of the satellite broadcast tuner
42
, digital frequency components of the serial clock and serial data are multiplexed on a local oscillation signal and supplied to the signal line. It increases pseudo noise (PN) components in a signal outputted from the satellite broadcast tuner
42
, deteriorates the picture quality of a video signal in the signal, and reduces the carrier-to-noise ratio of the satellite broadcast tuner
42
.
Similarly, the known satellite broadcast receiver has the construction in which the control unit
44
, IC
45
for modulation and CATV signal converting unit
46
are connected. Consequently, when the serial clock (SCL) and serial data (SDA) is transmitted between the control unit
44
and the IC
45
for modulation, the serial clock and serial data is transmitted also to the CATV signal converting unit
46
via the I
2
C bus
50
. In this case as well, when the serial clock and serial data is supplied to the CATV signal converting unit
46
, the serial clock and serial data is mul
Alps Electric Co. ,Ltd.
Faile Andrew
Tran Hai V.
LandOfFree
Satellite broadcast receiver which is not influenced by... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Satellite broadcast receiver which is not influenced by..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Satellite broadcast receiver which is not influenced by... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3216126