United States Patent [19J
`Crosby et al.
`
`[54] MULTI-CHANNEL DIGITAL VIDEO
`TRANSMISSION RECEIVER WITH
`IMPROVED CHANNEL-CHANGING
`RESPONSE
`
`[75]
`
`Inventors: Jeffrey W. Crosby, Sherman Oaks;
`Michael A. Friedman, Fountain Valley,
`both of Calif.
`
`[73] Assignee: Hughes Electronics Corporation, El
`Segundo, Calif.
`
`[21] Appl. No.: 08/877,929
`
`[22] Filed:
`
`Jun. 18, 1997
`
`Int. Cl.6
`....................................................... H04N 5/50
`[51]
`[52] U.S. Cl. ........................... 348/387; 348/725; 348/731
`[58] Field of Search .................................. 348/10, 11, 13,
`348/385, 387, 554, 555, 725, 726, 731-733;
`370/436, 478, 345, 343; 455/179.1, 185.1,
`186.1, 186.2, 187.1, 191.1; H04N 7 /13,
`7/08, 5/44, 5/50, 5/455
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,602,279
`4,903,126
`4,975,771
`5,161,023
`5,469,431
`
`7 /1986 Freeman .................................... 348/13
`2/1990 Kassa ti y ... ... ... .... ... ... ... ... ... .... .. 348/385
`12/1990 Kassa ti y ... ... ... .... ... ... ... ... ... .... .. 348/385
`11/1992 Keenan ................................... 348/732
`11/1995 Wendorf et al. ........................ 370/478
`
`I 1111111111111111 11111 lllll lllll lllll lllll 111111111111111 111111111111111111
`US005933192A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,933,192
`Aug. 3, 1999
`
`5,600,378
`5,790,177
`5,861,881
`
`2/1997 Wasilewski ............................... 348/10
`8/1998 Kassa ti y .... ... ... ... ... ... .... ... ... ... .. 348/385
`1/1999 Freeman et al. .......................... 348/10
`
`Primary Examiner-David E. Harvey
`Attorney, Agent, or Firm-John A. Crook; Michael W. Sales
`
`[57]
`
`ABSTRACT
`
`A multi-channel digital video receiver (e.g. DBS) includes a
`tuning unit with two tuner modules and a decoder unit with
`two decoder modules. These tuner and decoder units enable
`the receiver to simultaneously produce decoded video and
`audio signals for two separately-tuned channels. The signals
`for the channel currently selected by the user are tuned and
`decoded by one set of tuner and decoder modules. The
`decoded signals for the selected channel are sent to an output
`stage (e.g. encoder), where the signals and their output are
`encoded for use on an attached presentation device (e.g.
`television, audio processor, computer, etc.) Simultaneously,
`a microcontroller predicts the next channel the user will
`select and causes the other tuner and decoder modules to
`begin tuning to and decoding the signals for that predicted
`next channel. A third set of tuner and decoder modules can
`be added to enable the receiver to begin tuning to and
`decoding the signals for another likely next channel. Since
`the receiver begins tuning to the predicted next channel even
`before a new channel is requested, an expected channel(cid:173)
`change command can be processed more quickly than in a
`conventional receiver.
`
`28 Claims, 3 Drawing Sheets
`
`40
`
`42
`
`44
`
`50
`
`64
`
`22
`
`24
`
`12
`
`20
`
`10./
`
`30
`
`70
`
`Comcast, Ex. 1106
`
`1
`
`

`

`U.S. Patent
`US. Patent
`
`Aug.3, 1999
`Aug. 3, 1999
`
`Sheet 1 0f3
`Sheet 1 of 3
`
`5,933,192
`5,933,192
`
`‘1'
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`2
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`

`

`U.S. Patent
`
`Aug. 3, 1999
`
`Sheet 2 of 3
`
`5,933,192
`
`USER ACTION
`
`TUNER & DECODER
`MODULES A
`
`TUNER & DECODER
`MODULES B
`
`DISPLAY
`
`1'
`
`TUNES
`CH. 200
`
`+
`
`PRE-TUNES
`CH. 201
`
`' '
`
`CH. 200
`(from A)
`
`'I
`
`~
`
`r
`
`\.
`
`PRE-TUNES
`CH. 202
`
`CH. 201
`(from B)
`
`SELECTS
`CH. 200
`
`SELECTS
`CH. UP
`
`SELECTS
`CH.UP
`
`PRE-TUNES
`CH. 203
`
`CH. 202
`(from A)
`
`FIG. 2
`
`3
`
`

`

`U.S. Patent
`
`Aug. 3, 1999
`
`Sheet 3 of 3
`
`5,933,192
`
`USER
`ACTION
`
`TUNER
`&DECODER
`MODULES A
`
`TUNER
`&DECODER
`MODULES B
`
`TUNER
`&DECODER
`MODULESC
`
`DISPLAY
`
`SELECTS
`CH. 200
`
`SELECTS
`CH.UP
`
`SELECTS
`CH. DOWN
`
`lit
`
`'if
`
`'if
`
`PRE-TUNES
`CH. 199
`
`TUNES
`CH. 200
`
`PRE-TUNES
`CH. 201
`
`"
`CH. 200
`(from 8)
`
`~
`
`PRE-TUNES
`CH. 202
`
`PRE-TUNES
`CH. 199
`
`CH. 201
`(from C)
`
`CH. 200
`(from 8)
`
`FIG. 3
`
`4
`
`

`

`5,933,192
`
`1
`MULTI-CHANNEL DIGITAL VIDEO
`TRANSMISSION RECEIVER WITH
`IMPROVED CHANNEL-CHANGING
`RESPONSE
`
`20
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`2
`The microcontroller may predict that the user will repeat
`his or her last channel-change command. Thus, if the
`currently-selected channel has been selected by a channel-up
`(or channel-down) command, the microcontroller may pre-
`s diet that the channel above ( or below) the currently-selected
`BACKGROUND OF THE INVENTION
`channel will be the next selected channel. If the currently(cid:173)
`selected channel has been selected by a previous-channel
`1. Field of the invention
`command, the microcontroller may predict that the next
`The invention relates generally to methods and apparatus
`channel will be the previous channel.
`for receiving and processing multi-channel digital video
`The microcontroller 70 may also predict the next channel
`transmissions, and more particularly to a digital broadcast 10
`based on the user's past actions when watching the current
`satellite (DBS) receiver capable of providing quicker
`channel. Thus, if channel 201 is currently being processed
`response to a user's command to change channels.
`for use and the user has frequently switched from channel
`2. Description of Related Art
`201 to channel 240 (whether directly or by rapid incremental
`The time required for a conventional multi-channel digital
`video receiver, such as a DBS receiver, to change channels 15 changes through the intermediate channels without signifi(cid:173)
`cant "dwell" time, or within a given time window, or
`is comparatively greater than the time needed to change
`otherwise), the microcontroller may predict that the next
`channels in a conventional analog video ( e.g. television)
`channel to be selected will be channel 240.
`system. In either system, reception processing for a selected
`Upon predicting the next channel to be selected, the
`channel (e.g. program) requires a tuner to tune to the desired
`microcontroller causes the second tuner module to begin
`carrier frequency and polarity, select the desired packets,
`tuning to that predicted next channel. Since the receiver
`and demodulate an otherwise process the selected data
`begins tuning to the predicted next channel even before a
`before the desired programming can be sent for output (e.g.
`new channel is requested, many of the steps necessary to
`display).
`tune that new channel (e.g. acquisition of a complete
`Formulating a digital DBS broadcast typically requires
`25 I-frame) can be completed before the next channel-change
`additional steps. High capacity systems typically utilize
`command is entered. Since fewer steps remain when the
`signal compression techniques, such as MPEG2 encoding,
`command is entered, a repeated or common channel-change
`as well as effective error correction coding. To receive and
`command can be completed more quickly than in a conven-
`process these signals, most DBS receivers adjust for the
`tional receiver.
`appropriate polarity and frequency of the received satellite 30
`transmission, filter and select the required data packets
`corresponding to the desired output (e.g. channel), and
`demodulating the channel data (e.g. program or other
`content). Most DBS systems further enable and lock error(cid:173)
`correction circuitry into the new channel before transporting 35
`the resulting data packets to a digital decoder. In decoding
`the video data packets in an MPEG stream, the next com(cid:173)
`plete video frame (I-frame) is generally entered to fill
`memory buffers before video images are re-encoded to an
`analog signal for display on the user's screen. In a high- 40
`capacity, multiple-channel DBS system, conventional DBS
`receivers may require several tenths of a second, e.g. from
`0.3 to more than 1 second, to change channels.
`These delays are particularly annoying to a television user
`that is sequentially scrolling through adjacent channels, an 45
`operation that many users like to perform quickly.
`
`Those skilled in the art should be able to understand the
`invention upon reading the following description in con(cid:173)
`junction with the accompanying drawings, in which:
`FIG. 1 is a schematic of one embodiment of a DBS
`receiver in accordance with the present invention;
`FIG. 2 is a block diagram illustrating operation of the
`receiver of FIG. 1; and
`FIG. 3 is a block diagram illustrating operation of an
`alternate embodiment of a receiver in accordance with the
`invention.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`
`SUMMARY OF THE INVENTION
`The multi-channel digital video receiver and method that
`are the subject of this invention can provide significantly
`quicker channel changes when a user scrolls through adja(cid:173)
`cent channels or otherwise selects a predictable new chan(cid:173)
`nel.
`The receiver includes a tuning unit with two or more tuner
`modules and a decoder unit with an equal number of decoder
`modules. These tuning and decoding modules help enable
`the receiver to simultaneously produce decoded video and
`audio signals for two or more separately-tuned channels.
`One tuner module is tuned to the channel currently selected
`by the user, and its decoded signals are processed for use on 60
`the user's presentation device (e.g. television set, computer,
`audio processor, etc.).
`The other tuner module is used to tune to a predicted next
`channel. While one channel is being processed for use, a
`microcontroller predicts the next channel likely to be 65
`selected and causes the tuning unit to begin tuning to that
`predicted next channel.
`
`FIG. 1 illustrates a preferred embodiment comprising a
`DBS receiver 10 used to process a DBS broadcast transmis(cid:173)
`sion. The DBS broadcast transmission, including audio and
`video information for a range of DBS channels, is received
`so by a satellite antenna (not shown) and fed to the receiver 10
`through a suitable number (e.g. a pair) of DBS inputs 12.
`Each DBS input is preferably a standard RF input that can
`be readily connected to a coaxial cable 14 from the antenna
`to receive e.g. an L-band intermediate signal from LNBs
`ss located at the antenna. Other transmission or distribution
`systems may similarly be used (e.g. terrestrial broadcast or
`cable) without departing from the scope of the present
`invention.
`The DBS broadcast transmission inputted through the
`DBS inputs 12 is sent to a tuning unit 20 comprised of two
`tuner modules 22, 24. Each of the tuner modules tunes and
`demodulates at least a portion of the transmission to produce
`a set of DBS channel data packets for a different channel.
`Two L-band inputs are preferably used so that each tuner
`module may be independently connected to a separate
`processor in a dual LNB outdoor unit. This allows each tuner
`module to independently select (via known techniques such
`
`5
`
`

`

`5,933,192
`
`3
`as use of variable e.g. 13- or 18- volt de signals) either
`left-hand circular polarization (LHCP) signals or right-hand
`circular polarization (RHCP) signals, as required by the
`channel to be tuned. In systems utilizing fewer channels or
`higher capacity cable 14 or other interconnects, a single 5
`cable may suffice. In systems where two cables are not
`sufficient ( e.g. where multiple satellites having different
`locations or frequency bands are utilized) additional cables
`14 or other interconnects may be required.
`Alternatively, one of the two DBS inputs 12 may be 10
`dedicated to a selected signal set (e.g. RHCP or a given
`satellite location) while the other DBS input is dedicated to
`another signal set ( e.g. LHCP or an alternate satellite
`location). In such a system, the e.g. RHCP and LHCP
`transmissions are each delivered to the receiver through its 15
`own interconnect, e.g. coaxial cable 14, into a suitable
`selector switch or multiswitch (not shown) associated with
`each tuner module. Each tuner module 22 or 24 sends a
`signal, such as a 13- or 18-volt signal, which its associated
`switch interprets as a request for either the first or second ( or 20
`other) signal set (e.g. RHCP or the LHCP signal containing
`the desired channel). The switch acts upon the signal by
`connecting the tuner module to the appropriate DBS input
`having the desired signal set. Using a switch with each tuner
`module allows the receiver 1 0 to include three or more tuner 25
`modules without the need for additional coaxial lines from
`the receiver to one or more LNB's, and allows use of
`multiple receivers at a location in conjunction with a single
`antenna system.
`Preferably, each tuner module 22 or 24 includes a QPSK
`or other demodulator for demodulating the broadcast. Such
`demodulators are in widespread use in the U.S. in receivers
`adapted to commercial DBS systems. It is also preferable
`that each tuner module includes a forward error correction
`module to correct channel coding errors. The use of such
`modules is also well-known in the U.S. The tuning unit 20
`outputs DBS channel data packets for each of two selected
`user or DBS channels to a transport circuit 30. In the
`transport circuit, the data packets are filtered in conventional
`ways for further processing. Filtering can include, for
`example, selecting the required data packets in a multi(cid:173)
`plexed data stream corresponding to the desired channel,
`and sending the data packets of one or both of the tuned
`channels to a conditional access module to assure that access
`to the content is authorized. Preferably, the audio, video, and
`data packets are segregated. While the illustrated transport
`circuit functions the same as a transport circuit in a conven(cid:173)
`tional DBS processor, it preferably has sufficient capacity to
`handle the additional data packets produced for a second
`DBS channel. Alternatively, two ( or more) transport circuits
`may be utilized.
`The filtered data packets are sent through the transport
`circuit 30 to a digital video and audio decoding unit 40. The
`decoding unit includes two separate decoder modules 42, 44.
`Each decoder module decodes the filtered data packets for
`one of the tuned DBS channels to provide decoded video,
`audio, and/or data signals for that tuned channel. This
`decoding can be done in any conventional way. Preferably,
`each decoder module includes separate audio, video, and/or
`data decoders, and decodes the filtered signals in accordance
`with the MPEG or other applicable standard.
`In a preferred embodiment, one set of decoded video,
`audio, and/or data signals is outputted from the decoding
`unit 40 to an output stage, such as an analog encoder 50. The
`encoder processes the decoded signals to produce an appro- 65
`priate signal for output to a presentation device, such as a
`television set, video monitor, audio processor, data
`
`4
`processor, etc. In certain embodiments, analog video encod(cid:173)
`ing is done by a conventional NTSC encoder. In an all(cid:173)
`digital television system, of course, such analog video
`encoding would be unnecessary. The output signal may be
`outputted through an output jack 62, such as a conventional
`RF, S-video, SVGA, or other format of analog or digital
`output, which can be connected to the presentation device
`by, e.g., a conventional cable 64. Where the circuits are
`incorporated within a presentation device, such outputs are
`optional.
`The selection of which DBS channels will be tuned by the
`tuning unit 20, and which set of decoded video and audio
`signals will be sent to the encoder 50 for ultimate output to
`the user's presentation device, are controlled by a micro(cid:173)
`controller 70. As described below, the microcontroller is
`programmed to control the tuning unit so that one tuner
`module 22 or 24 is tuned to the channel currently selected by
`the user, and the other tuner module is tuned to a predicted
`next channel.
`The predicted next channel will often be an adjacent
`channel. "Adjacent", for these purposes, signifies that two
`channels are consecutive in the list of channels being offered
`to, or optionally selected by, the user. If, for example, the
`user is authorized to receive both channels 200 and 201, then
`those channels are "adjacent." If, on the other hand, the user
`is authorized to receive channels 200 and 202, but not
`channel 201, or has selected a user preference list that
`includes channels 200 and 202 but not channel 201, then
`channels 200 and 202 are "adjacent."
`The microcontroller 70 may predict the next channel
`based on the last channel-change command. When the user
`has selected a channel by a channel-up or channel-down
`command, he or she will often repeat the same command
`when selecting the next channel to be viewed. Accordingly,
`when a user enters a channel-up or channel-down command,
`the microcontroller may be programmed to predict that the
`next channel-change command will be a repetition of that
`command. Thus, if the current channel was selected by a
`"channel-up" command, the microcontroller may be pro(cid:173)
`grammed to predict that the next channel requested will be
`the next adjacent channel above the currently-selected chan(cid:173)
`nel. If the currently-selected channel was selected by a
`"channel-down" command, the microcontroller may be pro-
`45 grammed to predict that the next selected channel will be the
`next adjacent channel below the currently-selected channel.
`When a new channel is selected by some other command,
`the microcontroller may be programmed to predict that the
`next selected channel will be one of the adjacent channels,
`50 the previously-selected channel, or some other channel. It
`may be advantageous, for example, to program the micro(cid:173)
`controller to predict that, when the currently-selected chan(cid:173)
`nel was selected by a "previous-channel" command, the next
`selected channel will be the previously-selected channel,
`55 even if that channel is not an adjacent channel.
`When a new channel is entered by means of a keypad, the
`same or a similar algorithm may, in some circumstances, still
`be applied. If the new channel is an adjacent one, the next
`channel may still be predicted to be the next sequential
`60 channel. Similarly, if the user uses the keypad to enter the
`same channel that would have been retrieved by a "previous(cid:173)
`channel" command, the microcontroller 70 may be pro(cid:173)
`grammed to predict that the next channel will be the
`previously-selected channel.
`In some cases, a user may use other techniques to change
`between two channels of interest. For example, the user may
`use the channel-up or channel-down commands repeatedly,
`
`40
`
`30
`
`35
`
`6
`
`

`

`5,933,192
`
`5
`in rapid succession, to move quickly through the intervening
`channels. The microcontroller 70 may be programmed to
`recognize this pattern and discriminate the end points or
`channel of apparent interest. By way of example, an inter(cid:173)
`vening channel may be ignored if the "dwell" time on that 5
`channel is less than a selected minimum, indicating that the
`intervening channel is not one of interest. A general time
`window might also be utilized, such that the microcontroller
`70 waits a determined time after an initial channel change
`commands before noting a new channel. In this manner, the 10
`system ignores any transient channels within the time win(cid:173)
`dow. Other algorithms may also be employed.
`The microcontroller 70 can also predict the next channel
`based on past experience of when the currently-selected
`channel was previously used (or processed for use). The
`microcontroller may, for example, apply a stochastic process
`model such as a Markov chain model for predicting the next
`channel the user will select. In such a system, the micro(cid:173)
`controller could store records of each user's past channel(cid:173)
`change commands. Preferably, this information would be
`stored in non-volatile memory. When any channel is being
`used, the microcontroller would access the records for
`channel-changes made when that channel was previously
`used and determine the probable next channel based on that
`subset of past channel-change experience.
`The prediction of the probable next channel could be
`made by simply counting the number of times the user
`switched from the current channel to each possible next
`channel, and selecting the channel to which the user has in
`the past most frequently switched. For example, if channel
`201 is currently being processed for use and the user has
`previously switched from that channel to a new channel ten
`times, the microcontroller can use the records of those ten
`prior channel-changes to determine the probable next chan(cid:173)
`nel. If, in those past experiences with channel 201, the user 35
`has switched six times to channel 200, three times to channel
`205, and one time to channel 210, the microcontroller can
`predict from that information that the most probable next
`channel will be channel 200 (six of ten past events equals a
`0.6 probability of a switch to channel 200, versus three of ten 40
`past events equals a 0.3 probability of a switch to channel
`205, versus a one of ten past events equals a 0.1 probability
`for a switch to channel 210, versus zero in ten past events
`equals a 0.0 probability for a switch to any other channel).
`Of course, the microcontroller 70 could evaluate this
`subset of past channel-change experience in different ways
`to predict the most probable next channel. For example, past
`experience could be weighted in favor of recent experience
`so that, in the example stated above, channel 205 might be 50
`selected as the most probable next channel if the three
`switches from channel 201 to 205 happen to be the last three
`switches that the user made when using channel 201, and
`were all made during the current period of use.
`Of course, the information based on past experience could
`also supplement ( or be supplemented with) other
`information, such as recent use of the channel-up, channel(cid:173)
`down, or previous-channel command, the keypad, or other
`past channel-change experience.
`By predicting the next channel and causing one of the
`tuner modules 22 or 24 to begin tuning to that predicted next
`channel before a new channel is requested, the microcon(cid:173)
`troller 70 can enable the receiver 10 to process a repeated or
`correctly-predicted channel-change command much more
`quickly than a conventional receiver can. FIG. 2 illustrates
`this for an embodiment of the invention in which the next
`channel is predicted based on the user's last channel-change
`
`6
`command. It shows a series of user commands and the
`resulting operations of two sets of tuner and decoder mod(cid:173)
`ules A and B. Upon a user's command for channel 200, the
`microcontroller causes tuner and decoder modules A to tune
`to channel 200. Once the necessary frequency and polarity
`have been selected, the transmission has been demodulated,
`channel coding errors have been corrected, and the resulting
`data packets have been filtered and decoded to provide
`decoded video and audio signals, the microcontroller causes
`the decoded signals to be forwarded to the encoder 50 for
`processing for output to a user's television set.
`As illustrated, the user next enters a channel-up com(cid:173)
`mand. In a conventional DBS receiver, this request for a new
`channel would require a re-initiation of the same steps
`15 described above. In the illustrated receiver 10, however,
`decoded signals for the newly-selected channel 201 are
`already available through decoder module B. While the
`tuner and decoder modules A were tuning to channel 200,
`the microcontroller 70 predicted that the next channel the
`20 user would select would be channel 201. Accordingly, it
`caused tuner module B to begin tuning to that channel.
`While data packets for channel 200 were being filtered and
`sent to decoder module A, data packets for channel 201 were
`being filtered and sent to decoder module B. Decoder
`25 module B began decoding the signals for channel 201 while
`decoder module A decoded the signals for channel 200.
`Thus, when the user selected channel 201, all that the
`receiver 10 needed to do to complete the channel change was
`to confirm that the newly selected channel was the predicted
`30 channel being processed by the other tuner/decoder, send the
`signals from decoder module B to the encoder 50, encode
`the signals, and send them to the user's television set. As a
`result, response to the user's request for a new channel was
`significantly improved.
`In this embodiment of the invention, the user's selection
`of channel 201 by a channel-up command also causes the
`microcontroller 70 to predict that the next channel selected
`will be channel 202. (If the user is not authorized to receive
`channel 202, or if the user has selected a preference list that
`does not include channel 202, the microcontroller would
`predict that the next channel would be the next-higher
`channel on the user's preference list that the user is autho(cid:173)
`rized to receive.) The microcontroller causes tuner module A
`to begin tuning to that next-predicted channel. When the
`user subsequently repeats the channel-up command, the
`change to channel 202 ( or to the next appropriate channel)
`can again be completed much more quickly than in a
`conventional receiver.
`With the illustrated receiver 10, improved channel-change
`response is available only if a user selects the predicted next
`channel; that is, if the microcontroller was "correct" in
`predicting the next channel. However, even if the user
`selects a new channel that is not the predicted new channel
`55 (i.e., the prediction was "wrong"), the channel change can
`still be completed as quickly as in a conventional receiver.
`FIG. 3 illustrates one way in which the inclusion of a third
`tuner module and a third decoder unit can be used to
`improve channel-change response even when a user does not
`60 repeat his or her last channel-change command. As
`illustrated, the user's selection of channel 200 causes tuner
`module B to begin tuning to channel 200. Meanwhile, the
`microcontroller 70 predicts that the next channel will be one
`of the two adjacent channels and causes tuner modules A and
`65 C begin tuning to channels 199 and 200, respectively.
`When the user subsequently enters a channel-up
`command, the microcontroller 70 causes the signals from
`
`45
`
`7
`
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`

`5,933,192
`
`10
`
`40
`
`7
`the tuner and decoder modules C to be sent to the encoder
`50 while tuner modules A and B re-tune to the next channels
`above and below the newly-selected channel. As illustrated,
`the tuner module that is already tuned to previously-selected
`channel 200 (tuner module B) remains tuned to that channel,
`while the other tuner module (tuner module A) re-tunes from
`channel 199 to channel 202. In this way, the re-tuning of the
`tuning unit 20 requires only one tuner module to be re-tuned.
`While benefits of the invention could be derived from
`re-tuning tuner module A to channel 200 and re-tuning tuner
`module B to channel 202, programming the microcontroller
`to leave tuner module B tuned to the previously-selected
`channel may allow an even quicker channel change in some
`circumstances.
`After the channel is changed to channel 201, the user
`makes a channel-down or previous-channel command.
`Because tuner module B remained tuned to channel 200, the
`channel-change command can be processed quicker than in
`a conventional DBS receiver, even though the channel(cid:173)
`change command was not a repetition of the user's last
`channel-change command.
`A third tuner module can also be useful in a system that
`predicts the next channel based on past channel-changing
`experience. In such a system, the third tuner module can be
`programmed to begin tuning to the second-most-probable 25
`next channel. Preferably, the second-most-probable next
`channel would be determined by the same routine or formula
`used to determine the most probable next channel. In spe(cid:173)
`cific embodiments, one tuner may always remain tuned to
`the last-tuned channel (in the event of a "previous channel" 30
`command), while the other tunes to a channel predicted by
`any of the described or other predictive algorithms or logic.
`Selection or control of the mode of multi-tuner predictive
`functions may be pre-set, or may be user selectable. For 35
`example, user inputs (via switches, keypad, remote control,
`menu selections, or otherwise) may be provided to allow a
`user to input preference information, such as selecting a
`"simple" operation limited to channel-up, channel-down, or
`previous-channel predictions, or an "advanced" operation
`including more complex stochastic or other techniques.
`Other preference information may be used to "fine-tune" the
`predictive algorithms to best match the user's frequency and
`use patterns. Different preferred modes of operation may be
`employed for different users of the system and stored for 45
`retrieval and use when that user is commanding the system
`(e.g. in a user profile maintained for other purposes by the
`receiver 10). Thus the device may be configurable if desired
`to achieve a high degree of predictive accuracy for one or
`more given user(s).
`Benefits of the present invention are achieved as
`described by providing two or more tuner/decoder sections,
`feeding (selectively) an output stage. If desired, multiple
`output stages can also be provided, such that the next(cid:173)
`predicted signal(s) is also processed as required (e.g. NTSC 55
`encoded) for immediate display or use as requested. In such
`embodiments, switching between present and selected next
`channel outputs is done on the output-ready signals. In this
`manner, delays in the output stage processing are also
`avoided.
`Where multiple output stages are also provided, the
`device may further be configured to make the two (or more)
`output signals available for simultaneous display, e.g. at
`second outputs or internally as PIP or other multi-view
`features. In such embodiments, the user may view or oth(cid:173)
`erwise process ( e.g. in picture-in picture (PIP) or other
`multi-view format of a single display, or on multiple display
`
`8
`devices) both the selected channel and the next-predicted
`channel(s). This may further facilitate normal "surfing", and
`allows the viewer to watch or otherwise use two channels
`(e.g. when changing between two programs of interest by
`5 using "previous program" or other selection methods, and
`monitoring the alternate program by PIP or other methods).
`Further, by combining such embodiments with further user
`control options, the device may be optionally configured by
`the user to utilize at least a second of the two-or-more
`tuner/demodulator/output stage circuits to process a user(cid:173)
`selected second channel not utilizing the predictive features
`discussed. Thus the device can support flexible and fast
`channel-changing in a normal mode as described, and in a
`second mode output a selected second channel when desired
`(e.g. to allow watching of one program while recording
`15 another, PIP operation, second set operation, or otherwise).
`Of course, it should be understood that a wide range of
`other changes, modifications, and improvements can be
`made to the preferred embodiment described above. It is
`therefore intended that the foregoing detailed description be
`20 regarded as illustrative rather than limiting, and it should be
`understood that it is the following claims, including all
`equivalents, that are intended to define the scope of the
`invention.
`What is claimed is:
`1. A multi-channel digital video transmission receiver
`comprising:
`tuning and decoding units capable of tuning and decoding
`a digital transmission to simultaneously produce a set
`of decoded digital video signals for each of two or more
`tuned channels;
`a microcontroller programmed to respond to a user's
`request for a selected one of the two or more tuned
`channels by causing the set of signals for the selected
`channel to be outputted, predicting a next channel, and
`causing a second tuning unit to begin tuning the pre(cid:173)
`dicted next channel in addition to the selected channel.
`2. The receiver of claim 1, further comprising an analog
`encoder capable of encoding at least those signals corre(cid:173)
`sponding to the selected channel for output to a presentation
`device.
`3. The receiver of claim 1, in which the microcontroller is
`programmed to predict that the next channel will be a
`channel adjacent to the selected channel.
`4. The receiver of claim 1, in whic