U.S. patent application number 10/170514 was filed with the patent office on 2002-10-17 for method and apparatus for cross-connection of video signals.
Invention is credited to De Haas, Scott.
Application Number | 20020152471 10/170514 |
Document ID | / |
Family ID | 23038259 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020152471 |
Kind Code |
A1 |
De Haas, Scott |
October 17, 2002 |
Method and apparatus for cross-connection of video signals
Abstract
A switched telecommunication access system for providing video
data to gateway devices. The switched telecommunication access
system includes a switched multicasting station for transmitting
video data in response to receiving a video data request signal;
and a plurality of gateway devices coupled to the switched
multicasting station, the gateway devices sending video data
request signals to the switched multicasting station and receiving
video data from the switched multicasting station, at least one
gateway device of the plurality of gateway devices including a
controller for sending a video data request signal to the switched
multicasting station and for routing video data received from the
switched multicasting station in response to the video data request
signal; and a plurality of video decoders coupled to the controller
for decoding the video data received from the switched multicasting
station; where one stream of video data representing a video
program on a particular channel is sent from the switched
multicasting station to one gateway device of the plurality of
gateway devices even when the video program on the particular
channel is requested for display on more than one display device
coupled to the one gateway device.
Inventors: |
De Haas, Scott; (Santa Rosa,
CA) |
Correspondence
Address: |
Ararat Kapouytian
Morrison & Foerster LLP
425 Market Street
San Francisco
CA
94105-2482
US
|
Family ID: |
23038259 |
Appl. No.: |
10/170514 |
Filed: |
June 12, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10170514 |
Jun 12, 2002 |
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09272067 |
Mar 18, 1999 |
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6408436 |
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Current U.S.
Class: |
725/95 ;
348/E5.005; 348/E7.07; 348/E7.073; 348/E9.039; 370/229; 375/E7.019;
375/E7.268; 725/97; 725/98 |
Current CPC
Class: |
H04Q 11/0478 20130101;
H04N 21/6405 20130101; H04N 21/434 20130101; H04L 2012/5616
20130101; H04N 7/17336 20130101; H04L 2012/5642 20130101; H04N
21/6338 20130101; H04N 21/2365 20130101; H04N 9/641 20130101; H04N
7/17354 20130101; H04N 21/4347 20130101 |
Class at
Publication: |
725/95 ; 725/97;
725/98; 370/229 |
International
Class: |
H04N 007/173; H04L
001/00; H04J 001/16; H04J 003/14; G06F 011/00; H04L 012/26; G08C
015/00; G01R 031/08 |
Claims
1. A switched telecommunication access system comprising: a video
source; a switched multicasting station connected to said video
source; and a plurality of display devices, connected to said
switched multicasting station, for displaying video presentations
selected by a user; wherein said switched multicasting station
receives only a single copy of each video presentation selected by
at least one of the plurality of display devices even if more than
one of the plurality of display devices selected same video
presentation, said switched multicasting station transmitting
appropriate video presentations to appropriate ones of said
plurality of display devices including multicasting the same video
presentation to the more than one of the plurality of display
devices that selected the same video presentation.
2. The switched telecommunication access system of claim 1, wherein
said switched multicasting station includes a broadband digital
terminal.
3. The switched telecommunication access system of claim 1, wherein
said switched multicasting station includes an optical network
unit.
4. The switched telecommunication access system of claim 1, wherein
said switched multicasting station includes a broadband network
unit.
5. The switched telecommunication access system of claim 1, wherein
said switched multicasting station includes a universal service
access multiplexer.
6. The switched telecommunication access system of claim 1, wherein
said switched multicasting station includes a gateway device.
7. The switched telecommunication access system of claim 1, wherein
said switched multicasting station includes a broadband digital
terminal connected to said video source; and a plurality of optical
network units, each of said optical network units connected to said
broadband digital terminal and a subset of said plurality of
display devices; wherein said broadband digital terminal receives
only a single copy of each video presentation and multicasts a
single copy of the video presentation to each of said optical
network units that have display devices connected thereto that have
selected the video presentation, each said optical network unit
transmitting appropriate video presentations to appropriate ones of
the plurality of display devices connected thereto including
multicasting the same video presentation to the more than one of
the plurality of display devices that selected the same video
presentation.
8. The switched telecommunication access system of claim 1, wherein
said switched multicasting station includes a broadband digital
terminal connected to said video source; and a plurality of gateway
devices, each of said gateway devices connected to said broadband
digital terminal and a subset of said plurality of display devices;
wherein said broadband digital terminal receives only a single copy
of each video presentation and multicasts a single copy of each
video presentation to each of said gateway devices that have
display devices connected thereto that have selected the video
presentation, each said gateway device transmitting appropriate
video presentations to appropriate ones of said plurality of
display devices connected thereto including multicasting the same
video presentation to the more than one of said plurality of
display devices that selected the same video presentation.
9. The switched telecommunication access system of claim 1, wherein
said switched multicasting station includes an optical network unit
connected to said video source; and a plurality of gateway devices,
each of said gateway devices connected to said broadband digital
terminal and a subset of said plurality of display devices; wherein
said optical network unit receives only a single copy of each video
presentation and multicasts a single copy of each video
presentation to each of said gateway devices that have display
devices connected thereto that have selected the video
presentation, each said gateway device transmitting appropriate
video presentations to appropriate ones of said plurality of
display devices connected thereto including multicasting the same
video presentation to the more than one of said plurality of
display devices that selected the same video presentation.
10. The switched telecommunication access system of claim 1,
wherein said switched multicasting station includes a broadband
digital terminal connected to said video source; a plurality of
optical network units connected to said broadband digital terminal;
and a plurality of gateway devices, each of said gateway devices
connected to one of said plurality of optical network units and a
subset of said plurality of display devices; wherein said broadband
digital terminal receives only a single copy of each video
presentation and multicasts a single copy of each video
presentation to each of said plurality of optical network units
that have display devices connected thereto that have selected the
video presentation, each of said plurality of optical network units
receives only a single copy of each video presentation and
multicasts a single copy of the video presentation to each of said
plurality of gateway devices connected thereto that have display
devices connected thereto that have selected the video
presentation; and each of said plurality of gateway devices
transmitting appropriate video presentation to appropriate ones of
said plurality of display devices connected thereto including
multicasting the same video presentation to the more than one of
said plurality of display devices that selected the same video
presentation.
11. The switched telecommunication access system of claim 1,
wherein the video presentations are transmitted in Asynchronous
Transfer Mode (ATM) cells.
12. The switched telecommunication access system of claim 1,
wherein only one Virtual Path Identifier (VPI) and one Virtual
Channel Identifier (VCI) is used to identify a particular video
presentation on a particular channel even when the particular video
presentation on the particular channel is requested for display on
more than one display device connected to said switched
multicasting station.
13. The switched telecommunication access system of claim 1,
wherein the video presentations that are multicast are
compressed.
14. The switched telecommunication access system of claim 13,
wherein the compressed video presentations are compressed utilizing
Moving Pictures Experts Group (MPEG) compression standards.
15. The switched telecommunication access system of claim 1,
wherein said switched multicasting station includes a multicasting
table that tracks each video presentation and each display
device.
16. A switched telecommunication access system comprising: a video
source; a switched multicasting station connected to said video
source; a plurality of gateway devices, each of said gateway
devices connected to said switched multicasting station; and a
plurality of display devices, each display device connected to one
of said plurality of gateway device, for displaying video
presentations selected by a user; wherein said switched
multicasting station receives only a single copy of each video
presentation and multicasts a single copy of each video
presentation to each of said gateway devices that have display
devices connected thereto that have selected the video
presentation, each said gateway device transmitting appropriate
video presentations to appropriate ones of said plurality of
display devices connected thereto including multicasting the same
video presentation to the more than one of said plurality of
display devices that selected the same video presentation.
17. The switched telecommunication access system of claim 16,
wherein the video presentations transmitted from said switched
multicasting station are compressed.
18. The switched telecommunication access system of claim 17,
wherein said plurality of gateway devices include video decoders
capable of uncompressing the compressed video presentations.
19. The switched telecommunication access system of claim 16,
further comprising a plurality of secondary switched multicasting
stations connected between said switched multicasting station and
said plurality of gateway devices, wherein said switched
multicasting station receives only a single copy of each video
presentation and multicasts a single copy of each video
presentation to each of said plurality of secondary switched
multicasting stations that have gateway devices connected thereto
that have selected the video presentation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 09/272,067, filed Mar. 18, 1999, and entitled
METHOD AND APPARATUS FOR CROSS-CONNECTION OF VIDEO SIGNALS.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to telecommunication access
systems and, in particular, to switched video telecommunication
access systems.
[0004] 2. Description of the Related Art
[0005] In many existing telecommunication access systems, such as
cable systems and satellite systems, video programming on a
predefined number of channels is broadcast to all subscribers units
in the system. In other words, each subscriber unit receives the
video programming of all the channels in the system. For each
subscriber unit, the number of video programs that may be displayed
at any point in time is limited by the total number of display
devices (in addition to the number of display devices having the
picture-in-picture feature) within the subscriber unit that are
connected to the system. More specifically, for each subscriber
unit, the number of video programs displayed at any point in time
is limited by the number of display devices activated for
displaying video programming. As the number of display devices
within a subscriber unit, and more specifically the number of
activated display devices within a subscriber unit, is generally
much smaller than the number of channels in the system, video
programs on a number of channels are not displayed at any given
time. The broadcasting of undisplayed video programs occupies
valuable bandwidth which is wasted.
[0006] Another disadvantage of broadcasting programs to all
subscribers is that of potential unauthorized viewing of
pay-per-view or premium channel programs. This problem is largely
overcome by sending programs on pay-per-view and premium channels
in scrambled mode and providing only authorized subscribers with
means for unscrambling the programs. However, the problem is far
from entirely eliminated as these programs may be descrambled by
using unauthorized descrambling devices.
[0007] One prior art method of reducing theft is to use a switched
rather than a broadcast system to transmit video programs to the
subscriber units. In a switched system, video programs are sent to
a subscriber unit in response to a request received from the
subscriber unit. Although prior art switched systems generally
provide greater protection against unauthorized viewing of
programs, they do not address other issues that are recognized and
addressed by the present invention.
SUMMARY OF THE INVENTION
[0008] One of the issues recognized and addressed by the present
invention is the minimization of bandwidth used when transmitting a
video program on a particular channel to multiple display devices
associated with one gateway device. Thus, when a video program on a
particular channel is requested for display on more than one
display device associated with one gateway device, only one stream
of video data representing the video program on the particular
channel is transmitted to the one gateway device. Sending only one
stream of video data representing a video program on a particular
channel, rather than sending multiple streams of video data
representing the video program on the same channel, reduces the
amount of bandwidth used for transmitting to a gateway device a
video program on a particular channel requested for display on
multiple display devices associated with the gateway device. The
gateway device distributes the video program to one or more display
units within the gateway device on which the video program on the
particular channel is requested to be displayed.
[0009] Similarly, only one stream of video data representing video
programming on a particular channel is sent from the broadband
digital terminal (BDT) to an optical network unit (ONU) even when
more than one gateway device associated with a particular ONU
request the video data on the particular channel. Therefore, only
one stream of video data representing video programming on a
particular channel is transmitted from the BDT to any one ONU. The
ONU then sends the video data to each gateway device associated
with the ONU which requests the video program on the particular
channel. For each gateway device requesting the video program on
the particular channel, the ONU sends only one stream of video data
representing the video programming on the particular channel.
Sending of one rather than multiple streams of video data
representing the video programming on the particular channel saves
considerable bandwidth that would otherwise be wasted on sending
multiple copies of the video program on the particular channel from
the BDT to the one or more ONUs and from the one or more ONUs to
the one or more gateway devices.
[0010] In a presently preferred embodiment of the present
invention, the stream of video data is transmitted to the gateway
device in ATM cells. Video data representing the video programming
on a particular channel is identified with only one Virtual Path
Identifier (VPI) and one Virtual Channel Identifier (VCI)
throughout the system. Therefore, only one VPI and one VCI is used
to identify the video data representing the video programming on a
particular channel as the video data is transmitted from the BDT to
any ONU in the system. Similarly, the same VPI and VCI is used to
identify the video data representing the video programming on the
particular channel as the video data is transmitted between any ONU
and any gateway device associated with the ONU. This allows sending
only one stream of video data representing the video programming on
a particular channel from the BDT to any one ONU and from any one
ONU to any one gateway device associated with the ONU. Use of only
one VPI and one VCI, rather than a multiple number of VPIs and
VCIs, reduces the amount of bandwidth used for transmitting video
data from the BDT to the ONUs and from the ONUs to the gateway
devices. The ONU multicasts the video program to all the gateway
devices associated with the ONU requesting the video program.
Similarly, the gateway device multicasts the video program to all
the display devices associated with the gateway device on which the
video program on the particular channel is to be displayed.
[0011] In a presently preferred embodiment of the invention, the
switched telecommunication access system comprises: a switched
multicasting station for transmitting video data in response to
receiving a video data request signal; and a plurality of gateway
devices coupled to the switched multicasting station, the gateway
devices sending video data request signals to the switched
multicasting station and receiving video data from the switched
multicasting station, at least one gateway device of the plurality
of gateway devices comprising: a controller for sending a video
data request signal to the switched multicasting station and for
routing video data received from the switched multicasting station
in response to the video data request signal; and a plurality of
video decoders coupled to the controller for decoding the video
data received from the switched multicasting station; wherein one
stream of video data representing a video program on a particular
channel is sent from the switched multicasting station to one
gateway device of the plurality of gateway devices even when the
video program on the particular channel is requested for display on
more than one display device coupled to the one gateway device.
[0012] In another presently preferred embodiment of the invention,
the switched telecommunication access system comprises: a switched
multicasting station for transmitting video data in response to
receiving a video data request signal; and a plurality of gateway
devices coupled to the switched multicasting station, the gateway
devices sending video data request signals to the switched
multicasting station and receiving video data from the switched
multicasting station, at least one gateway device of the plurality
of gateway devices comprising: a plurality of video decoders for
decoding video data received from the switched multicasting
station; and a controller for sending a video data request signal
to the switched multicasting station and for routing video data
received from the switched multicasting station in response to the
video data request signal, the controller comprising: a plurality
of selectors, each selector of the plurality of selectors receives
a plurality of video data streams and in response to a control
signal from the controller selects one video data stream of the
plurality of video data streams for transmission to one of the
plurality of video decoders.
[0013] The present invention is explained in more detail below with
reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a block diagram of a presently preferred
embodiment of a switched video telecommunication access system
(SVTAS) of the invention.
[0015] FIG. 2 is a detailed block diagram of the presently
preferred embodiment of the gateway device of the invention.
[0016] FIG. 3 is a block diagram of display devices coupled to the
modulators of the gateway device in one embodiment of the present
invention.
[0017] FIG. 4 is a block diagram of display devices coupled to the
modulators of the gateway device in another embodiment of the
present invention.
[0018] FIG. 5 is a block diagram of a presently preferred
embodiment of the gateway ASIC of the present invention showing the
digital receivers in the gateway ASIC and the devices in the
gateway ASIC used for routing video data in the gateway ASIC.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] The present invention comprises a novel switched video
telecommunication access system and related methods for
cross-connection of video signals transmitted by the access system.
The following description is presented to enable any person skilled
in the art to make and use the invention, and is provided in the
context of a particular application and its requirements. Various
modifications to the preferred embodiment will be readily apparent
to those skilled in the art, and the generic principles defined
herein may be applied to other embodiments and applications without
departing from the spirit and scope of the invention. Thus, the
present invention is not intended to be limited to the embodiment
shown, but is to be accorded the widest scope consistent with the
principles and features disclosed herein.
[0020] Channel is herein used to refer to an equivalent of a
television, cable, or a satellite channel. As such, channel herein
is intended to have its commonly understood meaning and is not to
be confused with an Asynchronous Transfer Mode (ATM) or other type
of channel.
[0021] As used herein video data is intended to cover both audio
and video data. More generally, video data is intended to encompass
wide bandwidth signals generally, of which video signals are
typical.
[0022] FIG. 1 is a block diagram of a presently preferred
embodiment of a switched video telecommunication access system
(SVTAS) of the invention. In a presently preferred embodiment of
the invention, the SVTAS 100 comprises a broadband digital terminal
(BDT) 110, X optical network units (ONUs) 120, and X times Y
gateway devices 130, where X and Y are integers. In presently
preferred embodiments, ONUs 120 may comprise universal service
access multiplexers (USAMs) or broadband network units (BNUs). In a
presently preferred embodiment, BDT 110 comprises a BDT available
from Next Level Communications of Rohnert Park, Calif., as part
number 750-00008. Also, in a presently preferred embodiment, ONUs
120 comprise BNUs or USAMs available from Next Level Communications
of Rohnert Park, Calif., as part numbers 750-00150 and 750-00086,
respectively. In a preferred embodiment, X and Y are 64 and 32,
respectively. The BDT 110 receives video signal on input lines 105,
which in a presently preferred embodiment comprise optical carrier
level 12 (OC-12) lines. The BDT 110 is coupled to the X ONUs 120 by
lines 115, which in a presently preferred embodiment comprise
optical carrier level (OC-3) lines. Each ONU 120 is coupled to Y
gateway devices 130 by lines 125, which in the presently preferred
embodiment comprise twisted pair very high speed digital subscriber
lines (VDSLs). Each gateway device 130 is in turn coupled to one or
more display devices (shown in FIGS. 3 and 4), such as televisions,
via line 135.
[0023] In the presently preferred embodiment of the invention, when
one or more gateway devices 130 request the video program on a
particular channel of the SVTAS system 100, then the BDT 110 sends
the video data to the ONU or ONUs 120 associated with that one or
more gateway devices 130 requesting the video program on the
particular channel. Thereafter, the ONU 120 multicasts the
requested video program to the one or more gateway devices 130
requesting the video program. Each gateway device 130 receiving the
video program in turn sends the video program to the one or more
display devices associated with the gateway device on which the
video program is requested for display.
[0024] On each line 115, only one stream of video data representing
the video program on a particular channel, without duplication
other than to the extent necessary for error checking and
correcting, is transmitted from the BDT 110 to the ONU or ONUs 120
whose associated gateway device or devices request the video
program on the particular channel independent of the number of
gateway devices requesting the video program. The BDT 110 registers
in its multicasting map or table all the ONUs 120 to which the
video data representing the video programming on a particular
channel is transmitted. Similarly, on each line 125, only one
stream of video data representing the video program on a particular
channel, without duplication other than to the extent necessary for
error checking and correcting, is transmitted from the ONU 120 to
the gateway device or devices 130 associated with the ONU 120 which
request the video program independent of the number of display
devices on which the video program is to be displayed. Each ONU 120
registers in its multicasting map or table all the gateway devices
130 to which the video data representing the video programming on a
particular channel is transmitted.
[0025] The sending of only one stream of video data representing
the video program on a particular channel saves considerable
bandwidth that would otherwise be wasted in sending multiple stream
of video data representing multiple copies of the video program on
the same channel. This saving of bandwidth occurs both on lines 115
between the BDT 110 and ONUs 120 and on lines 125 between the ONUs
120 and the gateway devices 130. Similarly, this saving is repeated
for each channel in the SVTAS 100. In other words, for each channel
in the SVTAS 100, no more than one stream of video data
representing the video program on the channel is transmitted on any
one line 115 or on any one line 125.
[0026] In a presently preferred embodiment of the invention, video
data on lines 115 and 125 is transmitted in ATM. Furthermore, the
video data representing the video program on a particular channel
is identified with only one VPI and one VCI throughout the SVTAS
100. Thus, the same VPI and VCI identify the video data
representing the video program on a particular channel in the BDT
110, on all the lines 115, in all the ONUs 120, on all the lines
125, and in all the gateway devices 130 of the SVTAS 100. The video
data representing the video program on each channel thus has its
own VPI and VCI that is the same throughout the SVTAS 100.
[0027] FIG. 2 is a detailed block diagram of the presently
preferred embodiment of the gateway device of the invention, which
may be a residential gateway device. The gateway device 130 is
coupled to ONU 120 (shown in FIG. 1) by line 125. Analog filter
202, which in a presently preferred embodiment comprises a VDSL
filter, receives analog signals transmitted by ONU 120 on line 125.
Thereafter, the analog filter 202 conditions the analog signals,
including amplifying the analog signals, and sends them to
transceiver 204. In a presently preferred embodiment, transceiver
204 comprises a BCM6010 chip, which is a transceiver available from
Broadcom Corporation of Irvine, California. In a presently
preferred embodiment, the transceiver 204 includes an analog to
digital (A/D) converter, a digital to analog (D/A) converter, a
modulator, a demodulator, and ATM Utopia Levels 1 and 2 standard
interfaces. The transceiver 204 extracts digital information from
the analog signals received from analog filter 202. Thereafter, the
transceiver 204 transmits the digital information to processor 210
via line 205, which in a presently preferred embodiment comprises a
standard Utopia bus. In a presently preferred embodiment, the
processor 210 comprises a MOTOROLA 860 Segmentation and Reassembly
(SAR) Power PC, which is available from Motorola, Inc. The
processor 210, among other things, converts the digital information
received from transceiver 204 into ATM protocol data units (PDUs).
The processor 210 is coupled to an Ethernet port 211 and a
telephone port 212. In a presently preferred embodiment, Ethernet
port 211 and telephone port 212 comprise RJ 45 and RJ 11 ports,
respectively. The Ethernet port 211 allows connecting a computer
(not shown), such as a personal computer, to the internet by way of
the line 125, ONU 120, line 115, BDT 110, and a link between BDT
110 and the internet. Telephone port 212 allows connecting a
telephone line to the gateway device 130 for purposes, of among
other things, displaying, on at least one display device coupled to
the gateway device, the telephone number of the telephone line from
which an incoming call is made to the telephone line connected to
the telephone port 212. The processor 210 is also coupled to the
processor bus 213, which in a presently preferred embodiment is a
MOTOROLA 860SAR Power PC bus.
[0028] Memory 214, memory 215, and memory 216, which comprise
dynamic random access memory (DRAM), DRAM expansion, and flash
memories, respectively, are also coupled to the processor bus 213.
Also coupled to the processor bus 213 is a gateway application
specific integrated circuit (gateway ASIC) 220.
[0029] The gateway ASIC 220 is also coupled to an infrared (IR)
receiver 221 and an ultra high frequency (UHF) receiver 222. A user
inputs commands to the IR remote control (not shown) or the UHF
remote control (not shown) which transmit the desired commands to
the IR receiver 221 or the UHF receiver 222, respectively. IR
receiver 221 and UHF receiver 222 receive analog signals from the
IR remote control and the UHF remote control, respectively. IR
receiver 221 and UHF receiver 222 convert their respectively
received analog signals into digital signals and transmit the
digital signals to the gateway ASIC 220, more specifically to the
IR digital receiver 521 (shown in FIG. 5) and the UHF digital
receiver 522 (shown in FIG. 5) in gateway ASIC 220, respectively,
which forward the digital signals to the processor 210 via
processor bus 213. As is well known to those skilled in the art,
the user may also input requests using a user interface (not shown)
of the gateway device 130 other than the remote control devices
either in conjunction with or in place of the remote control
devices. One of the commands that may be input by a user is a
request to display on a particular display device in the subscriber
unit video programming on a particular channel of the SVTAS 100.
Such a command is transmitted from the gateway ASIC 220 to the
processor 210. The processor 210, then transmits the request to the
BDT 110. In response to the request, the BDT 110 transmits to the
gateway device 130 the video programming on the requested channel
in ATM using only one VPI and one VCI to identify the video
programming on the requested channel. If the video programming on
the requested channel is requested to be displayed on additional
display device or devices within the subscriber unit, the BDT 110
does not use another VPI and VCI for transmitting the requested
programming to the additional device or devices. As mentioned
above, in the presently preferred embodiment of the SVTAS 100 of
the present invention, only one VPI and one VCI is used for
transmitting the video programming on a particular channel to the
gateway device 130 of a subscriber unit in order to save bandwidth
that would otherwise be wasted in using more than one VPI or VCI
for transmitting video programming on a particular channel to more
than one display device within a subscriber unit.
[0030] The gateway ASIC 220, among other things, converts the ATM
PDUs received from the processor 210 into a suitable video format
for decoding by video decoders 230, which are preferably digital
video decoders. In a presently preferred embodiment, gateway ASIC
220 converts the ATM PDUs received from processor 210 into MPEG
data as video decoders 230 comprise MPEG decoders. More
specifically, in a presently preferred embodiment, video decoders
230 comprise SGS5500 MPEG decoders, which are available from ST
Microelectronics, also known as SGS Thompson. In FIG. 2, gateway
ASIC 220 is shown as being coupled to N video decoders 230. N is an
integer greater than or equal to one, represents the maximum number
of display devices that may be coupled to the gateway device 200,
and in a presently preferred embodiment is equal to 4. In a
presently preferred embodiment of the invention, the bus 225
coupling the gateway ASIC 220 to each of the video decoders 230
comprises an MPEG transport and an oversampled (OS) link. The MPEG
transport includes data, packet clock and bit clock lines. The OS
link is a control data bus that includes data in and data out
lines. The OS link provides a communication path between the
processor 210 and the video decoders 230 by way of the gateway ASIC
220. The processor 210 controls the operation of the video decoders
230 by providing each video decoder 230 with control signals via
the OS link indicating, for example, when the video decoder should
start decoding, stop decoding, and what video data to output. Each
video decoder is in turn coupled to an audio decoder 235, which is
preferably a digital audio decoder. In a presently preferred
embodiment, audio decoder 235 comprises an SGS4600 audio decoder,
which is a Dolby AC3 audio decoder also available from ST
Microelectronics. Each video decoder 230 and audio decoder 235 is
coupled to a modulator 240. Each modulator 240 receives signals
from the video decoder 230 and audio decoder 235 to which it is
coupled. Thereafter, each modulator 240 modulates the received
signals onto carriers to produce broadcast type signals compatible
with standard televisions and transmits the modulated signals to a
display device (shown in FIGS. 3 and 4), such as a television. In a
preferred embodiment, modulators 240 comprise RF modulators, such
as TDA6060, an RF modulator, available from Siemens AG. In one
embodiment of the invention, at least one video decoder 230
provides both Separate Video (S Video) and Composite Video outputs
to a display device to which it is connected. As is known to those
skilled in the art, the S Video and Composite Video outputs are
sent to the display device without being modulated.
[0031] In one embodiment of the invention, such as that shown in
FIG. 3, the modulators 240 are coupled to a coaxial combiner 305.
Coaxial combiner 305 is in turn coupled to display devices 310 and
routes the outputs of modulators 240 to the appropriate display
devices. In a second embodiment, such as that shown in FIG. 4,
there is no coaxial combiner between the modulators 240 and the
display devices 310. In the second embodiment, each modulator is
coupled to one display device and sends its output to that one
display device.
[0032] FIG. 5 is a block diagram of a presently preferred
embodiment of the gateway ASIC 220 of the present invention showing
the digital receivers in the gateway ASIC and the devices in the
gateway ASIC used for routing video data in the gateway ASIC.
Gateway ASIC 220 includes N buffers 505, N MPEG transport
generators 510 and N multiplexers 515. In a presently preferred
embodiment, buffers 505 are 32 bit wide random access memory (RAM)
units having a storage capacity of about 10 ATM PDUs, more
specifically each buffer 505 has a storage capacity of 1024 bits (1
kbit) by 32 bits. Additionally, buffers 505 are first-in-first-out
(FIFO) buffers. Buffers 505 are coupled to the processor bus 213
and receive ATM PDUs therefrom. The processor 210 determines the
first available buffer 505 and sends incoming data thereto. Each
buffer 505 is coupled to one MPEG transport generator 510. Each
buffer 505 sends data that it receives to the MPEG transport
generator 510 to which it is coupled. For example, the first MPEG
transport generator (i.e., MPEG transport generator 1) receives
data from the first buffer (i.e., buffer 1) while the Nth MPEG
transport generator (i.e., MPEG transport generator N) receives
data from the Nth buffer (i.e., buffer N). Each MPEG transport
generator 510 converts the ATM PDUs it receives from its
corresponding buffer 505 into serial MPEG packets. As can be seen
in FIG. 5, each MPEG transport generator 510 is coupled to all N of
the multiplexers 515. Each multiplexer 515 is coupled to one video
decoder (shown in FIG. 2). For example the first multiplexer is
coupled to the first video decoder (shown in FIG. 2) whereas the
Nth multiplexer is coupled to the Nth video decoder (shown in FIG.
2).
[0033] In a presently preferred embodiment, each of multiplexers
515 is an N.times.1 multiplexer, where N is as defined above. Under
the control of processor 210, each multiplexer 515 selects one of
its N inputs. For each multiplexer 515, the processor determines
which of the N inputs to the multiplexer 515 corresponds to the
video programming of the particular channel requested by the
display device 310 coupled to the multiplexer 515 and selects that
input for transmission to the display device 310. In a presently
preferred embodiment of the invention, for each multiplexer 515,
the processor 210 selects the input having the same VPI and VCI as
that of the video program requested by the display device coupled
to the particular multiplexer 515. For example, if the second
display device 310 requests video programming on a particular
channel and that video program on that particular channel happens
to be sent to the Nth buffer 505, then for the second multiplexer
515, the processor 210 selects the input from the Nth buffer 505
for transmission to the second display device 310. If the first
display device 310 also requests the video programming on the
particular channel requested by the second display device and as
before the video programming on the particular channel continues to
be sent to the Nth buffer 505, then for both the first and second
multiplexers 515, the processor 210 selects the Nth input for
transmission to the first and second display devices.
[0034] Gateway ASIC 220 also comprises IR digital receiver 521 and
UHF digital receiver 522, which receive digital signals from the IR
receiver 221 (shown in FIG. 2) and the UHF receiver 222 (shown in
FIG. 2), respectively. The IR digital receiver 521 and UHF digital
receiver 522 send digital signals to the processor 210 via bus
213.
[0035] In another embodiment of the present invention, gateway ASIC
220 does not include multiplexers 515. In such an embodiment, each
display unit 310 receives data from only one buffer 505.
Accordingly, the processor 210 sends requested data to the
buffer/buffers 505 corresponding to the display device/devices 310
requesting the data. Thus, if the second display device 310
requests video programming on a particular channel, then under the
direction of the processor 210, the requested video programming is
sent to the second buffer 505, i.e., the buffer which is coupled to
the second display device. If the first display device 310 also
requests the video programming requested by the second display
device 310, then the video programming is sent to the first buffer
505, i.e., the buffer coupled to the first display device 310, and
to the second buffer 505, which as stated above is the buffer
coupled to the second display device 310.
SUMMARY OF THE OPERATION OF THE SVTAS 100 OF THE INVENTION
[0036] The video data transmission process begins with a request by
a user to view the video program on a particular channel. In
addition to specifying a particular channel whose video program a
user wishes to view, the user also specifies the display device,
within the subscriber unit, on which the user wishes to view the
video program on the particular channel when there is more than one
display device coupled to the gateway device of the subscriber
unit. In a presently preferred embodiment, a request may be made
using a remote control device, such as a UHF or an IR remote
control device. Alternatively, some other user interface may be
provided by the gateway device 130 for allowing a user to enter a
request. The display device on which the video program is requested
for display may also be identified by the remote control device or
other user interface device used for making the request as each
remote control device or other user interface device may be
associated either on a permanent or temporary basis with only one
of the display devices coupled to the gateway device. The request
entered by the user is forwarded to the processor 210 in the
gateway device. The processor then forwards the request to the BDT
110. In a presently preferred embodiment, the processor 210
transmits a request to the BDT 110 in ATM. In response to the
request, the BDT 110 transmits the video program on the particular
channel to the ONU 120 associated with the requesting gateway
device. If the ONU 120 was already receiving the video program on
the requested channel because some other gateway device associated
with the ONU 120 had already requested the video program on the
requested channel, then no additional stream of video data
representing the video program on the requested channel would be
transmitted to the ONU 120 in response to the new request for the
same channel. Thus, the ONU 120 receives only one stream of video
data representing the video program on the requested channel
independent of the number of gateway devices coupled to the ONU 120
requesting the video program on the requested channel. Similarly,
the ONU 120 sends one stream of video data representing the video
program on the requested channel to the gateway device independent
of the number of display devices coupled to the requesting gateway
device on which the video program is requested for display. In a
presently preferred embodiment, the BDT 110 transmits data to the
gateway device 130 in ATM. Additionally, the -BDT 110 uses only one
VPI and one VCI to identify the video program on the particular
channel sent to one gateway device regardless of the number of
display devices, within the subscriber unit coupled to the gateway
device 130, on which the video program on the particular channel is
to be displayed.
[0037] In the gateway device 130, analog filter 202, conditions the
received analog signals, including amplifying the analog signals,
and sends them to transceiver 204. The transceiver 204 extracts
digital data from the analog signals received from analog filter
202. Thereafter, the transceiver 204 transmits the digital data to
the processor 210. The processor 210 converts the digital data
received from the transceiver 204 into ATM PDUs and sends the ATM
PDUs to the gateway ASIC 220.
[0038] In an embodiment of gateway ASIC 220 having multiplexers
515, the processor 210 sends the ATM PDUs to the first available
buffer 505 (which may be a buffer 505 other than the first buffer,
i.e., buffer 1, but which for purposes of illustration will herein
be referred to as the first buffer 505) among buffers 505.
Thereafter, the first buffer 505 transmits the ATM PDUs to the MPEG
transport generator 510 coupled to the first buffer 505. The MPEG
transport generator 510 converts the ATM PDUs into serial MPEG
packets and sends the serial MPEG packets to all the multiplexers
515 in gateway ASIC 220. Under the control of processor 210, only
the multiplexers 515 which are coupled to the display devices on
which the video program from the first buffer 505 is to be
displayed select the data of the first buffer 505 for further
transmission. The other multiplexers 515 either select data of a
buffer 505 other than the first buffer 505 or no data at all for
further transmission depending on what is requested by the display
device to which they are coupled.
[0039] In an embodiment of the gateway ASIC 220 having no
multiplexers, such as multiplexers 515, the processor 210 sends the
ATM PDUs only to the buffers 505 which are coupled to the display
devices on which the video program contained in the ATM PDUs have
been requested for display. In other words, the processor does not
simply send the ATM PDUs to the first available buffer 515.
Thereafter the buffer or buffers 505 receiving the ATM PDUs send
them to the MPEG transport generator or generators 510 to which it
or they are coupled. Each MPEG transport generator 510 receiving
ATM PDUs converts the ATM PDUs into serial MPEG packets and sends
the serial MPEG packets to the video decoder 230 to which it is
coupled.
[0040] Each video decoder 230 decodes the serial MPEG packets that
it receives and sends the decoded video data to the modulator 240
to which it is coupled. Similarly, each audio decoder 235 decodes
audio data that it receives and sends the decoded audio data to the
modulator 240 to which it is coupled. Each modulator 240 modulates
the video and audio data that it receives and sends the modulated
data to its corresponding display device 310. In one embodiment of
the invention, at least one video decoder 230 provides an S Video
or Composite Video output to the display device, thus bypassing
modulators 240.
[0041] While the present invention has been particularly described
with respect to the illustrated embodiments, it will be appreciated
that various alterations, modifications and adaptations may be made
based on the present disclosure, and are intended to be within the
scope of the present invention. While the invention has been
described in connection with what are presently considered to be
the most practical and preferred embodiments, it is to be
understood that the present invention is not limited to the
disclosed embodiment but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the scope of the appended claims.
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