Interactive video distribution systems – Video distribution system with local interaction – Interactive data transmitted in video signal band
Reexamination Certificate
2000-06-29
2004-08-03
Miller, John (Department: 2614)
Interactive video distribution systems
Video distribution system with local interaction
Interactive data transmitted in video signal band
C725S112000
Reexamination Certificate
active
06772438
ABSTRACT:
TECHNICAL FIELD
This invention relates to a system that retrieves data from a broadcast signal, such as a television broadcast signal.
BACKGROUND
Broadcast television in the United States is broadcast in accordance with the National Television Standards Committee (NTSC) broadcast television format standard. The NTSC broadcast format provides for the transmission of approximately thirty image frames per second. A particular frame includes two interlaced fields, in which each field includes 265½ horizontal scan lines.
FIG. 1
illustrates an example television broadcast frame
10
in accordance with the NTSC standard. Broadcast frame
10
may also be referred to as a “broadcast image.”
The broadcast and display of frame
10
is described in connection with a conventional analog television having a cathode ray tube (CRT) with an electron beam. A receiver portion of the television receives the broadcast NTSC signal and controls the electron beam such that the electron beam is scanned across the screen of the CRT to generate the appropriate image. The first nine horizontal scan lines (lines
1
-
9
) of the frame
10
are used to synchronize the television receiver and to return the electron beam to the top of the screen. The electron beam is disabled (also referred to as “blanked”) during the scan time of the first twenty-one scan lines so that the electron beam does not generate a visible line from the bottom of the screen to the top of the screen when being returned to the top of the screen. The first twenty-one scan lines are commonly referred to as the “vertical blanking interval” lines (or VBI lines).
The odd scan lines of the frame (i.e., frame line
1
, frame line
3
, etc.) are received first and are referred to as the “odd field”. The first twenty-one of these odd lines are the VBI lines. These first twenty-one lines synchronize the television receiver for the subsequent scanning of the horizontal scan lines of a viewable portion
12
of the frame
10
. During each horizontal scan line, the electron beam scans from left to right across the screen. When the electron beam reaches the right edge of the screen, the electron beam is returned to the left edge of the screen in preparation for the scanning of the next scan line. After the scanning of each odd scan line in viewable portion
12
, the electron beam is “blanked” as the electron beam is returned to left edge of the screen in preparation for the start of the next scan line. This blanking time is referred to as the “horizontal blanking interval” of the frame, which is indicated by a region
14
in FIG.
1
.
After the last odd scan line has finished, the even scan lines of the frame (i.e., frame line
2
, frame line
4
, etc.) are received and are referred to as the “even field”. As with the odd field discussed above, the first twenty-one scan lines of the even field are VBI lines. The electron beam is blanked during the scanning of the even VBI lines such that the electron beam can be returned to the top of the screen without generating a line on the screen. After the scanning of all the even VBI lines, the even scan lines of viewable portion
12
are scanned in a manner similar to the scanning of the odd scan lines discussed above. The viewable horizontal scan lines of the odd and even fields together cause the electron beam to scan across the screen of the television to create the viewable television image.
Generally, the entire vertical blanking interval is not required for vertical synchronization and returning the electron beam to the top of the screen. Typically, only VBI lines
1
-
9
of each field (i.e., the odd field and the even field) are used for these purposes. Thus, the remaining twelve VBI lines (lines
10
-
21
) are available for communicating other information.
For example, VBI line
21
provides a low speed communication sub-channel (the “line
21
sub-channel”). Data is encoded in the line
21
sub-channel in accordance with the encoding technique set forth in EIA-608, which is reserved by the Federal Communication Commission (FCC) for captioning services. The line sub-channel can transmit textual information, the current time, “V-chip” program rating codes, and closed captioning information. For example, a television receiver captures the closed captioning information and displays it as a text subtitle along with the television video to assist the hearing impaired.
VBI lines
10
-
20
are available for a higher-speed communication sub-channel for the communication of data. Data can be encoded in VBI lines
10
-
20
at a data rate sufficient to communicate web page content along with the television content being transmitted. The web page content is received and stored locally in the television receiver for future access. Later, when the web page content is to be displayed at a particular time in the television video, a “trigger” that identifies the web page content (e.g., by file name) is broadcast to the television receiver. When the trigger is received, the associated web page content is retrieved from the local storage device and displayed on the television screen.
However, certain televisions do not support the transmission of data over the VBI lines as discussed above. Furthermore, certain broadcast systems (such as digitally compressed satellite feeds and digital cable systems) may prevent the VBI-based information from being delivered to capable receivers. Thus, an alternate system sends information and triggers using line
21
instead of the VBI lines. Typically, the information transmitted using line
21
is relatively short, such as a uniform resource locator (URL) identifying the location of web page content to be retrieved by a television receiver (e.g., via a telephone line or other network connection). Since the television broadcaster transmits the same signal to many televisions, the broadcaster cannot tailor its signal to match the capabilities of a particular television receiver.
The system described herein addresses these and other problems by providing a television broadcast method and system that supports the transmission of data to various types of television receivers.
SUMMARY
The method and apparatus for retrieving data from a broadcast signal described herein allows a single television broadcast signal to support multiple types of television receivers. Different methods are used to communicate data and data identifiers along with the television program content, thereby allowing different types of television receivers to retrieve data from the broadcast signal.
In one implementation, a broadcast signal is received that includes a data identifier that identifies data associated with the broadcast signal. The broadcast signal also includes the data associated with the broadcast signal encoded in the broadcast signal. The data associated with the broadcast signal includes an indicator to ignore the data identifier contained in the broadcast signal. The procedure decodes the data encoded in the broadcast signal and ignores the data identifier contained in the broadcast signal.
In another embodiment, the indicator to ignore the data identifier contained in the broadcast signal includes a time period during which the data identifier should be ignored.
In a particular embodiment, the broadcast signal includes a broadcast image and the data identifier is broadcast in line twenty-one of the broadcast image.
In particular embodiments, the data associated with the broadcast signal is encoded in vertical blanking interval lines of the broadcast image.
REFERENCES:
patent: 6108706 (2000-08-01), Birdwell et al.
patent: 6400407 (2002-06-01), Zigmond et al.
patent: 6415438 (2002-07-01), Blackketter et al.
patent: 6460180 (2002-10-01), Park et al.
patent: 6557172 (2003-04-01), Carr
patent: 6560777 (2003-05-01), Blackketter et al.
patent: 6571392 (2003-05-01), Zigmond et al.
patent: 2003/0126621 (2003-07-01), Leak et al.
patent: 2003/0204854 (2003-10-01), Blackketter et al.
Blackketter Dean J.
Park Timothy F.
Beliveau Scott
Lee & Hayes PLLC
Microsoft Corporation
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