Interactive video distribution systems – Video distribution system with upstream communication – Transmission network
Reexamination Certificate
1999-03-26
2003-09-16
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Video distribution system with upstream communication
Transmission network
C725S071000, C725S078000, C725S080000, C725S082000, C725S149000, C725S121000
Reexamination Certificate
active
06622307
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
This invention relates in general to a signal distribution system. More particularly, it relates to a multiple-room signal distribution system that enables the efficient and cost effective distribution of a received wide band high frequency signal to different areas of a single general location (e.g., different rooms/floors of a single family unit, or different units/floors of a multiple-dwelling-unit).
(b) Description of Related Art
Audio/visual/data (AVD) signal distribution systems generally rely on either a cable network or on free-space propagation to deliver AVD signals, such as television signals, to individual users or subscribers. Cable-based AVD signal distribution systems transmit one or more individual AVD signals or “channels” over wire, while free-space propagation systems transmit one or more channels through free-space, i.e., in a wireless manner. Most large-scale cable and wireless signal distribution systems broadcast a broadband AVD signal having a plurality of individual AVD signals modulated onto one or more carrier frequencies within a discernable frequency band.
As an introduction to a signal broadcasting system that is capable of incorporating and utilizing the signal distribution system of the present invention,
FIG. 1
illustrates at
20
one example of a known wireless AVD signal broadcasting system. The illustrated broadcasting system
20
represents a Direct-to-Home (DTH) satellite communication system
20
having, generally, a transmission station
22
, a relay
24
, and a plurality of receiver stations, one of which is shown at reference numeral
26
. A wireless free-space link provides the communications medium between the transmission station
22
, the relay
24
, and the receiver station
26
. The transmission station
22
includes programming sources
28
, control data sources
30
, program guide (PG) data sources
34
, audio/video/data encoding systems
36
, uplink frequency converters
38
, and uplink antennas
40
. The relay
24
is preferably at least one geosynchronous or geo-stationary satellite. The receiver station
26
shown in
FIG. 1
includes a reception antenna/dish
50
, a low-noise-block (LNB)
52
connected to the antenna
50
, an integrated receiver/decoder (IRD)
54
, and a video display device (e.g., television)
60
.
In operation, the program source
28
receives video and audio programming from a number of sources, including satellites, terrestrial fiber optics, cable, or tape. The received programming signals, along with data signals from the control data source
30
and program guide (PG) data source
34
, are sent to the audio/video/data encoding system
36
where they are digitally encoded and multiplexed into a packetized data stream using a number of conventional algorithms. In a conventional manner, the encoded data stream is modulated and sent through the uplink frequency converter
38
which converts the modulated encoded data stream to a frequency band suitable for reception by the relay/satellite
24
. Preferably, the satellite frequency is Ku-band. The modulated, encoded data stream is then routed from the uplink frequency converter
38
to an uplink satellite antenna/dish
40
where it is broadcast toward the satellite
24
over the free-space link. The satellite
24
receives the modulated, encoded Ku-band data stream and re-broadcasts it downward toward an area on earth that includes the various receiver stations
26
. The LNB
52
of each receiver station
26
shifts the Ku-band signal down to an L-band signal which is conveyed from the LNB
52
to the IRD
54
.
Continuing with further details of the signal broadcasting system
20
,
FIG. 2
illustrates a more detailed diagram of the receiver station
26
shown in FIG.
1
.
As shown, the receiver station
26
includes the antenna
50
, the LNB
52
, and the IRD
54
which is connected to a display
60
(see FIG.
1
). The satellite antenna
50
transfers the received satellite signal to a conventional LNB circuit
52
which then passes the signal to the IRD
54
. The IRD
54
includes a tuner
56
, a demodulator
58
, an FEC decoder
62
, a microprocessor
64
, a transport IC
66
having a channel demultiplexer
68
, a decryption circuit
70
, a conditional access module
72
, an access card reader
74
, a system RAM
76
, an audio/video decoder circuit
78
having a random-access-memory (RAM)
80
, an audio decoder
82
, a video decoder
84
, an audio digital-to-analog converter
86
, an NTSC encoder
88
, an output driver
90
, a modem connection
92
, a set of microprocessor peripherals
91
(optional), a front panel user interface
94
, and a power supply
96
, coupled together as illustrated.
The transport IC
66
receives the transport stream of digitized data packets containing video, audio, scheduling information, and other data. The digital packet information contains identifying headers as part of its overhead data. Under control of the microprocessor
64
, the channel demultiplexer
68
filters out packets that are not currently of interest, and routes the data packets that are of interest through the decryption circuit
70
and the conditional access module
72
to their proper downstream destination. The decryption circuit
70
provides decryption for the data packets that have been encrypted. The conditional access module
72
provides access control by any conventional means. For example, access control may be achieved by requiring a data packet to have a proper authorization code in order to be passed to the decryption circuit
70
and/or the video decoder
78
. The access card reader
74
can interface with an access card (not shown) that will receive the packet authorization code, determine its validity, and generate a code that confirms to the transport IC
66
that the subject data packet is authorized. The conditional access module
72
also contains information necessary to perform a call back operation in which the microprocessor causes the modem
92
to call the satellite provider periodically to report data. The reported data is used for billing purposes and includes information regarding the programs and services that the viewer has accessed via the IRD module
54
. Various authorization codes required to perform the callback feature and used to inform the microprocessor
64
as to when callback is desired are determined via the conditional access module
72
.
The authorized data of interest are stored in the system RAM
76
for buffering, and the audio/video decoder
78
requests (via the microprocessor
64
) the RAM
76
contents as needed. The requested data is routed from the RAM
76
through the transport IC
66
to the audio/video decoder
78
. If the request is for video data, video data in the RAM
76
are routed through the transport IC
66
to the video/audio decoder's DRAM
80
until it is time for the data to be decoded. At that time, the data is routed to the video decoder
84
(which includes on-screen display circuitry) and the NTSC encoder
88
. The video decoder
84
reads in the compressed video data from the DRAM
80
, parses it, creates quantized frequency domain coefficients, then performs an inverse quantization, inverse discrete cosine transform (DCT) and motion compensation. At this point, an image has been reconstructed in the spatial domain. This image is then stored in a frame buffer in the DRAM
80
. At a later time, the image is read out of the frame buffer in the DRAM
80
and passed through the on-screen display circuitry to the NTSC encoder
88
. The on-screen display circuitry (located in the video decoder
84
) generates the graphics that allow text such as the electronic program guide data to be displayed. The NTSC encoder
88
converts the digital video signals to analog according to the NTSC standard or any other compatible standard, thereby allowing video to be received by and displayed on the display
60
(see FIG.
1
).
Turning now to the problems faced and addressed by the signal distribution system of the present invention, to a
Crook John A.
Faile Andrew
Hughes Electronics Corporation
Huynh Son P.
Sales Michael W.
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