Note: Descriptions are shown in the official language in which they were submitted.
~
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IVtI'ROVEVtENTS IN RECEIVERS FOR TELEVISION SIGNALS
The invention relates to improvements in receivers for television signals.
Back~ound of the Invention
At present most television broadcasting, regardless of medium over
which the sisal is broadcast (Te:-restrial, Cable, Satellite), is analogue
based
and comprises a single television senrice (e.g. SKY OI~'E, SKY SPORTS, SKY
MOVIES) transmitted on a carrier signal or channel. However, the use of
digital based broadcast technology is imminent. Digital broadcast technology
will enable television service companies to transmit in a single channel high
definition television progzainmes, or plural progammes at conventional
definition or multiple customer services, or a combination of these.
In a conventional analogue-based television broadcast system
prog-ammes (or "services") are broadcast by separate television service
companies on a single carrier signal ("channel"). In a digital based broadcast
system it is possible to broadcast plural services multiplexed together on a
single
carrier. Unless the context requires otherwise the term "channel" will be used
herein to refer to the bandwidth used by a single service to broadcast
television
i
programmes or other customer services. The term "channel" therefore
24 encompasses both an entire carrier signal (when the sir,;nal is used
entirely by a
single service) and a portion of a carrier signal (when the signal is shared
by
plural services).
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The ability to transmit multiple channels in a single carrier signal enables a
far greater
number of services to be provided in the digital domain than is possible in
the analogue domain.
Some of the channels in a carrier may be used to provide conventional
television programmes
while simultaneously other channels in the carrier are used to provide data
for other customer
services such as television programme listings, on-line programme ordering or
so-called pay-per-
view (PPV) services, and so on. Customer services should not be confused with
the "services"
provided by television companies as discussed hereinabove.
In our International (PCT) patent application published as WO 96/37996, there
is disclosed
a receiver for television signals, which receiver is arranged to receive video
signals comprising
video data, information data and audio signals comprising audio data and
information data. The
receiver is arranged to respond to viewer operation of a control device. The
receiver includes a
processor for processing selected information data to convert the same into
signals representative
thereof for output to a television in combination with the video signals. In
one mode of operation
the decoder responds to manipulation of the control device by causing brief
scheduling
information pertaining to programmes of a plurality of different TV signals to
be displayed over
the received signal. In another mode of operation the receiver is arranged to
display detailed
scheduling information pertaining to plural different television
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sisals. The receiver is operable to receive signals containing video data
representing a plurality of video clips. The processor is arranged to process
the
signals and to cause simultaneous display of the clips on a television screen.
The processor is arranged to respond to user manipulation of the control
device
by storing data for subsequent viewing of user selected pro°runmes. The
decoder may further comprise a modem and various types of digital storage
media including Hard Disk, CD-ROM drive, Digital Video Disk.
In addition to such television related services some of the channels in a
carrier may be used to provide on-line shoppin~ facilities by which a customer
rnay purchase goods and/or services from their own home. Such on-line
shopping is, of course, only possible if there is an element of interaction
between the goods/service provider and the customer. The term "interactive
services" will be used herein to refer generally to on-line shopping
facilities and
the like made available via one or more channels in a digital based broadcast
system.
Digital data multiple~cing techniques enable a single channel to carry
simultaneously multiple interactive services. In itself this creates a
problem.
Many customers will find bewildering the large number of interactive services
available to them. If customers become confused they will not make use of the
interactive services. Clearly, this is undesirable.
Transmission bandwidth is a finite resource and will remain at a
premium even if full advantage is taken of digital data compression
techniques.
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This presents a problem when it comes to providing an interactive service. On
the one hand it is
desirable to present high quality pictures and graphics. However, higher
quality necessitates the use
of a larger bandwidth. On the other hand it is desirable to keep costs down
because customers will
not make use of interactive services if they are significantly more expensive
than comparable high
street services.
In our International (PCT) patent application published as WO 97/23997, there
is disclosed
a receiver for television signals which receiver is arranged to receive video
signals comprising video
data and information data. The receiver is arranged to respond to viewer
operation of a control
device. The receiver includes a processor for processing selected information
data to convert the
same into signals representative thereof for output to a television in
combination with the video
signals. The receiver is arranged to respond to the information data to output
for display data
derived from said image data and said information data and representing an
inter-active image. The
receiver is responsive to viewer manipulation of the control device to vary
the inter-active image
and to establish a telecommunications link to a remote site for on-line
interaction via the inter-active
image between the viewer and the remote site. The interactive image may form
part of an
interactive services interface comprising a broadcast entry level and plural
broadcast interactive
levels. The inter-active services interface may comprise one or more on-line
interactive
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levels entered nom one of the broadcast interactive levels for establishing an
on-
line connection with a remote site.
Summary of the Invention
The present invention aims to facilitate the functionality and limit the
bandwidth used for the transmission of schedule data in the decoder and EPG
described in the aforementioned patent applications.
In one aspect the invention provides a receiver for reeeivin~ television
signals in a plurality of channels each defining a television pro~amme and at
t.east a signal in one of the channels comprising or further comprising
compressed data defining broadcast events in the channels from time to time,
the receiver being arranged to produce output sisals defining an image of
events in the programme schedule for displaying on a television screen and
comprising means for receiving data defining a dictionary representing text
portions. means for decoding the programme scheduling data to identify text
portions in the dictionary, and means for constructing the image of events
using the identified text portions_
In another aspect the invention provides a receiver for receiving
television signals in a plurality of channels each defining a television
programme and/or other services provided by a broadcaster, and a bouquet
identity and a sub-bouquet identity for the channel, the receiver comprising
means for storing a reference bouquet identity and one or more reference sub-
bouquet identities, means for comparing the bouquet identity and sub-bouquet
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ti
identity for a channel in a received signal with the reference bouquet and sub-
bouquet identities and means for outputting the received television signal for
display of the programme or other services defined thereby depending on the
comparison.
The ordering of the programmes or other services defined may also
depend on the comparison.
In a further aspect the invention provides a receiver for receiving
television signals in a plurality of channels each defining a television
programme and wherein the signals further comprise sorting data defining a
sorting list and schedulin' data defining a schedule of programme events, the
receiver being arranged to filter the scheduling data depending on the sorting
data to produce output signals defining an image of selected events in the
programme schedule for display as a filtered schedule on a television screen
depending on the sorting data.
The invention also provides a receiver for receiving television signals
in a first plurality of channels broadcast in a first broadcast network and a
second plurality of channels broadcast in a second broadcast network, the
receiver comprising a cache store for storing programme schedule data
transmitted from time to time in at bast one of the channels broadcast in the
first network, means for decoding the data in the cache store for display of a
programme schedule of the first broadcast network, and means for receiving
WO 99/667=t 1'CTIGB99/01873
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and decoding programme schedule data transmitted substantially continuously
in at least one of the channels broadcast in the second net<vork.
The invention provides a receiver for receiving television signals for a
plurality of channels which together provide a time-shifted service, the
television signals comprising unique identity data for each channel and
programme schedule data for a reference channel, tape receiver comprising
means for determining from the data for the reference channel a schedule for
each other channel and means for displaying a schedule of programmes for
each independently identified channel in the time shifted service.
The invention provides a receiver for receiving television signals in a
plurality of channels each defining a television programme and at least a
signal in one of the channels further comprising programme scheduling data
including pay-per view-events, the receiver being arranged to filter the data
pertaining to the pay-per-view events to produce output signals defining an
image of a schedule of the pay-per-view events for display on a television
screen.
The above and further features of the invention are set forth with
particularity in the appended claims and together with advantages thereof will
become clearer from consideration of the following detailed description of an
exemplan~ embodiment of the invention given with reference to the
accompanying drawings.
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Brief Description of the Drawines
Figure 1 is a schematic diagram of a television receiver system;
Figure 2 is a functional block diagram of a satellite decoder;
Figure 3 is a functional dia~-arn showing interaction between hardware
S and software of the decoder of Figure 2;
Figure .~ is a schematic dia~am representing a compressed text string;
Figure ~ is a schematic dia~am of a bouquet and a plurality of sub-
bouquets;
Figure 6 is a stylized example of a Box Ofnce menu; and
Figure 7 is a stylized example of a Box Ofnce screen.
Detailed Description of an Embodiment of the Invention
Svstem Overview
Referring now to Figure 1 of the accompanying drawings a television
receiver system 1 comprises a television (TV) 2, a digital inte~ated receiver
decoder 3 (decoder] connected to receive signals from a satellite dish antenna
4,
and a video cassette recorder 5 (VCR), and a modem 7. The system 1 optionally
further comprises a personal computer 6 (PC) and a games console 8 each
connected via respective Iines to the decoder 3. SCART connectors or other
standard connectors may be used as appropriate. 'The decoder 3 acts as an
interface between the TV 2 and the VCR 5, PC G, modem 7 and games console
$ and thus serves to control the system 1.
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Recei~~er/Decoder
Figure ? of the accompanying drawings shows the decoder 3 in heater
detail. The dish antenna receives sisals from a satellite (not shown). Signals
from the dish antenna =1 are input to a tuner 12 and from there to a
quadrature
6 phase shift key (QPSIVI demodulator I3. Demodulated si~aIs are error
corrected by wav of a forward error corrector circuit 14. Satellite (and
indeed
cablel programmes are usually scrambled to prevent unauthorised access by
non-authorised subscribers. The decoder 3 therefore comprises a conditional
access control circuit lb which co-operates with a smart card 16a to determine
whether the viewer has subscribed to a particular channel and is therefore
authorised to access the channel. Parental control over channel access is also
provided, at least in part, by the access control circuit 16. The decoder 3
further
comprises a descrambling circuit 17 which is controlled by the access control
circuit 16 to enable the descrambling of the sisal by authorised subscribers.
The received sienals comprise digitally encoded data. It is envisaged
that the data will be compressed using for example the DVB/1V1PEG 2 standards
which permit both programme data and additional data (for example interactive
service data) to be transmitted in a single channel. DVB/MPEG 2 enables high
compression ratios to be achieved.
Descrambled data is supplied to a transport / demultiplexor 15 which
separates the data into video data, audio data, user services data, programme
scheduling data etc. for distribution to various locations within the decoder.
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Demultiplexed signals are input to a video decompression and processing
circuit 18 utilising dedicated video RWI 1 i a, and an audio decompression and
processing circuit 19, operating according to the ivIPEG standard for example.
Decompressed video signals are input to a SC ART interface 20 for direct input
to the TV ? and to a PAL encoder 21 where they are encoded into the PAL
format for modulation by a UHF modulator ?'_-' for output to the UHF input of
the TV if so desired.
The system 3 is controlled by a processor ?3 which communicates with
the various units of the system via a bus 24. The processor ?3 has associated
with it ROM 2~ (optionally including a CD-ROM drive 2~a), RAM 26
(comprising both dynamic RAIN and static RAM) and a flash (non-volatile and
writable) memory 27. As will be explained in heater detail hereinafter the
processor 23 controls operation of the decoder 3 by controlling the tuner 12
to
receive signals for the desired channel from the dish antenna 4 and to control
1~ demultiplexing, descrambling and decompression so that the desired pro~amme
and/or interactive service data is displayed on the screen of the TV 2. Viewer
selection of desired progammes and customer services is controlled by way of a
remote control unit 28 which in response to viewer manipulation thereof
transmits control signals to a receiver 29 for input to the processor 23.
The system 3 further comprises a hish-speed data interface 30 and an
RS232 interface 31 providing a serial link. The high-speed data interface 30
and
the RS232 interface may be connected to the PC 6 and/or the games console 8
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of Fig. l andlor ocher digital equipment (not shown). The high speed data
interface 30 enables the system 3 to be connected to other devices (not shown)
for example to enabie reception of services transmitted via other media such
as
broadband cable and digital terrestrial broadcast. The decoder 3 further
comprises a modem interface 32 for connecting to a telephone network.
Gperation of the decoder 3, especially the processor ?3, is controlled by
sofrware that makes the processor ?3 responsive to control signals fi-om the
remote control unit ?8 and to data included in the sisal received by the dish
antenna 4 and in the memory units 25 to 27. .A schematic representation of the
interaction between hardware and software in the decoder 3 is shown in Figure
3
of the accompanying drawings. The data in an incoming signal is separated by
the transportldemultiplexer 15 into video data and information data. The
information data is distributed around the hardware and software, as will be
described in neater detail hereinafter. The video data and the audio data is
1 S demultiplexed and output in suitable form for supply to a TV by the MPEG
video and audio circuits 18 and 19. When information is to be displayed either
with or instead of the video, data representing the information is output in
suitable form for supply to the TV via an on-screen display (OSD) driver 33
and
the video circuit 18. Signals from the OSD driver 33 and the video circuit 18
are combined as appropriate before being supplied to the TV. Operation of the
software and hardware of the decoder 3 is based around an operating system 35.
The conditional access controller 16 has associated software which interfaces
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with the operating system. The processor ?3 has its own base operating system
37 which interfaces to the decoder operating system 3~. Applications such as
an
intelligent electronic programme guide (IEPG) 39 and other applications 40
including interactive sen~ices interface to the operating system 35 via an
applications interface 41 and associated application interpreter 42.
The software for conditional access applications such as the intelligent
electronic programme Guide 39 are installed permanently within non-volatile
memory, e.g. the RO~rI ?~, of the decoder 3, but variable information such as
new access codes and TV programme schedulinv details is updated regularly via
signals received from the dish antenna =i. Demodulated sisals from the
demodulator 13 are input to the transport demultiplexer I S which examines the
data to decide where it should be sent. From time to time sigtificant changes
may be made to conditional access codes or to the manner in which the
intelligent electronic programme guide (IEPG) 39 displays programme
information. Also, programmes for additional applications, say an interactive
shopping or banking service for example, are also supplied via the satellite
for
the decoder. Such application data is routed by the transporter 15 directly to
the
appropriate areas 40 of the store.
Operating data 43 is supplied on a substantially continuous basis in
every channel. The operating data 43 includes conditional access data 44
associated with a channel and/or programmes therein which enables the
conditional access controller 16 to determine whether or not access should be
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allowed to a particular pro~amme by descrambling the data therefor.
Additionally, operating data relating to interactive services is transmitted
in
dedicated interactive service channels which carry control and information
data
for use by the hardware and software of the processor ?3 and the associated
memory devices ?~ to ?7. Thus, the operating data 43 depicted in Figure 3 also
includes interactive senzce proms and information 46 (for example relating
to personal banking services) and indeed any other data 47 required on a
substantially continuous or regular basis For the aforementioned interactive
sernces.
The transportldemultiplexer 1~ is arranged to supply the operating data
43 to the processor 23. The data is acted upon by the operating system 35, the
conditional access andlor other operating software. The processor 23 responds
to the data by sending appropriate commands or information to other units
within the system. Control data is also transferred between the processor 23
and
such units as the demultiplexer 15, the video and audio decompressors 18, 19,
the remote control receiver 29 and the high-speed data interface 30 via
respective drivers 48 to 52.
The combined hardware and software of the decoder 3 enables the data
in received channels to be decoded for display of viewer selected programmes
and customer services. The scrambling is controlled on a continuous basis and
the decoder can be updated with new descrambling codes as and when required.
Data for interactive services is supplied and updated substantially
continuously
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and pro~ammes relating to newly selected interactive services are downloaded
into the decoder.
Operation of the decoder 3 in receiving and decoding data representing
television programmes and data defining scheduling and other information
related to the programmes is described in detail in our International (PCT)
patent application published as WO 96/37996, aforementioned. Operation of
the decoder 3 in providing interactive services is described in our
International
(PCT) application published as WO 9 7 /23997, aforementioned.
Within the Digital Video Broadcasting (DVB) standards for digital TV
transmission there exists a standard for the transmission of schedule
information
such that it can be decoded and presented correctly to subscribers in the form
of
an Electronic Programme Guide (EPG).
This DVB standard is known generally as the SI standard and can be
found in the specification: ETS 300 468, ETSI Digital Broadcasting Systems for
IS Television, Sound and Data Services; Specification for Service Information
(SI]
in Digital Video Broadcasting (DVB) Systems 2nd edition. Guidelines for
using the specification are given in ETSI ETR 211 - DVB SI Guidelines.
In order to allow broadcasters to utilise any proprietary features of their
EPGs the SI standard includes a methodology for extending the format of the
service information (SI) stream by the inclusion of private data tables and
descriptors.
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The above-described decoder 3 is. of course, desisted to support the
mandatory parts of the SI specification. Vv a have, however, extended
considerably certain aspects of the standard as is allowed by the standard.
The
extended standard will be referred to herein as the XSI specification. Among
other things, the XSI includes the following additional features:
1. Compression, regionalisation, ordering and sorting
techniques which are used for bandwidth efficient
transmission of data;
2. Organization and implementation of data caching;
3. Implementation of time-shifted services.
These additional features unique to the CSI specification, will be
described in detail in the following.
Compression
In order to save bandwidth on the transmission medium and memory
in the receiver text is compressed. A compression algorithm resident in the
decoder 3 uses "dictionaries" which - are received from the transmission
medium and held in memory, e.~. the RAM 26. The dictionaries may be
regarded as look-up tables in which portions of text are stored against table
addresses in the form of compressed text strings. Thus, instead of
transmitting full text over the transmission medium it is only necessary to
transmit the compressed text strings, thereby reducing the bandwidth
requirement for the transmission of text over the transmission medium.
WO 99/66721 PC'rlGB99/0I873
t6
Art example of a compressed text string 60 is shown in Figure =l of the
accompanying drawings. The string 60 comprises a field 61 of two bits which
identifies the version of the dictionary in which the relevant text is held.
The
string also comprises a field 63 of indefinite len~th containing data
pertaining
to compressed text.
Two versions of the dictionary are normally transmitted and a further
dictionary may be stored permanently (or for an extended period of time) in
the memory of the decoder 3. The transmission of two versions of the
dictionary enables the text compression to be optimised according to the data
currently being transmitted by allowing the dictionary to be updated over
time.
Special promotions in one week may no loner be available in the next or may
be replaced by another, different promotion causing different dictionaries to
be required for full efficiency. The transmission of two dictionaries reduces
the amount of memory required to store a dictionary because at any given time
1 ~ only a single dictionary need be stored in the decoder 3. Typically the
decoder
3 will be arranged to store in memory the most recently accessed dictionary,
be it for the present week or For the next week, and download the other
dictionary if necessary the next time data for the dictionary is broadcast
(typically every five seconds).
This approach minimises delay, at most, to ten seconds if data for the
required dictionary is not in the decoder's memory. It also minimises
bandwidth requirements because, instead of transmitting all text for every
~VU 99/66721 PCTlCB99l01873
17
page of the pro~rnme wide each time data for a page is transmitted, each
text string is transmitted only one in the dictionaries and the data for each
page is reduced to the compressed text strings, such as the compressed text
string 60 in Figure ~. On receipt of data for a page the decoder uses the
compressed text strings therein to look up the complete text in the
appropriate
dictionary and uses the text from the dictionary to reconstruct the full text
of
the page.
Several text fields are compressed including:
Extended service descriptions (including information about the
IO channel)
Names of each linked event (including the name or tile of a
programme)
Short event names
Extended event descriptions (including a brief synopsis of the
15 proeramme)
Special event messages (including discounts, say, for early ordering on
pay-per-view (PPV) services).
Regionalization
The DVB standard requires broadcasters to register with ETSI so-
20 called "bouquet" identities. Channel line-up information is carried in a
Bouquet Association Table (BAT) which is an optional DVB standard table.
One way in which services could be regionalized would be to register with
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1S
ETSI a different Bouquet iD for each region of interest, i.e. one Bouquet ID
for England, one for dales and one for Scotland for example. There are,
however, only a limited number of Bouquet IDs available which limits the
number of regions that may be defined for a given broadcast company.
Another problem is that the number of BATS increases with the number of
regions, thereby increasing bandwidth overheads.
In order to overcome this problem XSI inuoduces the notion of sub-
bouquets. Services are listed within sub-bouquets according to the contents of
sub-bouquet descriptors found within the BAT. Figure ~ of the accompanying
drawings shows a bouquet 70 which is identined by a bouquet ID and plural
sub-bouquets 71 to 75 each identified by a respective sub-bouquet ID. This
information is broadcast in a BAT. One of the sub-bouquets 71 may contain
information identi~ring services that are common to all regions, for example
nationwide services such as SKY1, SKY?. BBCI. Other sub-bouquets
contain information identifying services that are specific to each region, for
example the British ITV companies.
When a subscriber is first connected he or she provides information
(such as a post code) which is used to transmit to the decoder relevant
bouquet
and sub-bouquet LDs to enable the subscriber to receive and store the common
?0 services and regionalized service; for his region. Each decoder will
receive
the bouquet B7 together with the common sub-bouquet ID and the specific
region sub-bouquet B7 for the location of the decoder. A default may be set
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up to enable, say, a non-subscribing viewer to receive free services from
within the common and/or specific region sub-bouquets. The regional
information may be prestored in the viewing card. It will be appreciated from
the foregoing that such a scheme allows significant reduction in the bandwidth
used in describing regional channel line-ups.
Ordering
Channels are defined in a predetermined order and are designated a
channel number depending on that order. In order to enable the order in which
channels appear in the EPC to be different than the channel number order,
each sub-bouquet includes order numbers which are separate from the channel
number.
All services are assigned a unique service key which is their identifier
in XSI. Basically, the service key corresponds to the triplet (original
network
id, transport stream id, service id) which is the unique identifier of a
service as
defined in ETSI, ETS 3000 468.
Services are given attributes which vary on a sub-bouquet basis.
These attributes are used to inform the EPG application of the display
strategy
for the service. The attributes are:
Logical channel number (this is the "channel number"
as seen by the viewer).
Order number (this number is used to define the order
in which services appear in the EPG c~-id and listings).
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Navigation and display indicators (four flays tell
whether the service is accessible in channel surf mode, in
search & scan mode where listings are displayed over TV
viewing, whether the service is to be displayed in the full
listings screens and whether it cannot be locked out by parental
control).
Sorting
Data broadcast for the EPG includes true information such as the time
at which broadcast of a pro~amme is scheduled to start. It would, however,
10 be desirable to be able to sort pro~ammes ir. another order within the EPG,
for example alphabetical order.
Index lists of sorted events by time or alphabetically are computed in
the head end, sent over the air as part of the XSI and cached in the decoder
3.
This saves computer power in the decoder because sorting listings can be a
1~ very CPU intensive job. The sorted indices also convey information such as
genre/sub-genre, PPV post-buying window and other marketin?-oriented flags
(PPV, Critic's Choice, New Show, Event) that are used for filtering purposes
and to support the Box Office .functionality.
In addition to the above-described XSI, other improvements have been
made to the EPG in the decoder 3. The improvements will b~ described in the
following.
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~l
Caching
t1 cache store ?6a (see Figure 2) is provided in the decoder to enable
EPG data to be broadcast and built-up slowly over time, rather than being
broadcast continuously. The cache store 26a is a RWl device which may be
separate from or pan of the R~VI store 36. The cache store 36a is shown
separate from the RWI store 26 for the purpose of illustration in Figure ?.
Data caching is also used by the decoder to enable the decoder to be
used for a number of different broadcast nenvorks. Typically, the decoder will
be required to be able to receive broadcasts from a digital satellite
television
l0 network and a digital terrestrial television network. Conceptually, a
separate
EPG is provided within the decoder for each net<vork. Thus, in the case where
the decoder is required to receive both satellite and terrestrial broadcasts,
the
decoder may be regarded as providing both a satellite EPG and a terrestrial
EPG.
15 The satellite EPG in the decoder is arranged to cache data as and when
required taking information from the EPG transponder of the satellite
network. Information on the EPG transponder is cycled at a high transmission
rate in order that the EPG performs with a reasonable response period.
The bandwidth available for delivery of data to the terrestrial EPG in
20 the digital terrestrial environment is considerably less than that
available in
the satellite environment. Therefore, unlike in the satellite environment,
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__
within the terrestrial environment it is not possible to dedicate one
multiplex
to transmit the firll seven day schedule of EPG data at high speed.
J
Therefore in order to enable the full schedule of listings to be
displayed with a reasonable response rate the full schedule is "trickle"
transmitted on all terrestrial multiplexes and the terrestrial EPG stores the
complete schedule in the cache memory. This is possible even with the
smaller amount of memory available in the sec top box because there are a
small number of channels carried on the terrestrial network.
As shown in Figure 2. the decoder is made able to tune to digital
IO terrestrial TV by the addition of terrestrial tuner 12a to the high speed
port 30
of the set top box. (Similarly, a terrestrial set top box will be able to tune
to
digital satellite TV by the addition of a satellite tuner.) Ideally, in this
cases
the EPG resident in the set top box will be capable of seemlessly merging data
from the two environments.
An issue that because of memory limitations the combined network set
top box will not be capable of storing the entire satellite network schedule
in
its memory, neither would it be a good use of memory to store the entire
terrestrial schedule when only part of the satellite schedule is available.
In order to solve these difficulties when a terrestrial only set top box is
up~~raded to be capable of tuning to the satellite network then the caching
algorithm is changed to be that of a satellite set top box. Thus, the full
schedule is no longer held in set top box memory but sections of the schedule
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are obtained as required from the fast continuous transmission on the EPG
transponder of the satellite service. In order for this to work the schedule
for
the terrestrial listings schedule must also be transmitted in the data
transmitted
on the satellite EPG transponder.
With this desi~ any satellite capable set top box (i.e. a satellite only
system. a satellite system W th a terrestrial "side-car", or a terrestrial
system
with a satellite side-car) will obtain its schedule from the satellite EPG
transponder on demand and only caches the piece of the schedule currently in
use. ?~ terrestrial only set top box however will have a different caching
al~oriittm and caches the entire schedule for the terrestrial transmission.
The caching strategy can be refined by sending new caching
parameters over the air on a per platform basis. A platform is one type of
hardware from a certain manufacturer. This enables manufacturers to vary the
cost and performance of different models in their ranges by specifying
different sizes of cache store for different models. The parameters indicate
the
schedule depth of the listings that are to be cached and maintained in the
decoder as well as the schedule depth of the sorting indexes. Thus models
with larger cache stores will be able to store more information allowing the
owner to access the information more quickly.
Time-Shifted Services
Standard DVB SI allows time-shifted services to be defined. By way
of example, time-shifted services include the broadcasting of a single movie
in
WO 99/66721 PC'i'IGB99/01873
different channels at different start times. For example, as shown in Figure
6,
a movie may first be broadcast starting at 6:OOpm on a channel 75, then
broadcast of the same movie will start again on a different channel 76 at
6:30pm, then again at 7:OOpm on channel ~ ~ and so on. According to the
standard DVB SI one of the channels, i.e. channel 7~, is a reference channel
with a reference schedule and all other channels 76, 77 have schedules which
are time-shifted versions of the reference schedule. That is, the other
channels
76, 77 only differ from the reference channel i5 by the time-shift and cannot
have a channel name of their own.
Our XSI provides greater flexibility by allowing each time-shifted
channel to have a name which is different than that of the reference channel.
Thus, for example, a reference channel called "Box Office" could have time-
shifted channels called "Box Office 1", "Box Office 2", "Box Office 3", etc.
The "Box Office"
As discussed within our aforementioned earlier applications, within
the EPG there is a dedicated section for the display of Pay-Per-View (PPV)
programmes. PPV events include both one-off PPV events and near video on
demand PPV events. 'This is the "Box Office" section of the EPG.
Although the PPV programmes are also listed in the TV Guide section
of the EPG, Box Office has been created to encourage subscribers to browse
PPV progamming. The benefit of having a separate section that lists only
PPV events is that it will create a subscriber perception that because all
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,~
programming listed in this area incurs an extra charge it contains only
programmes of the highest value. This encourages the subscriber to use this
section of the EPG.
Whilst other EPGs list PPV programming within their normal listings
(some allow subscribes to apply filters within the normal listings to find the
PPV eventsl. as far as we can establish only the Sky EPG has an entire section
dedicated to this purpose.
Figure 6 of the accompanying drawings shows an example of a Box
Ofnce menu 80. The Box Office menu items allow access to listings by
l0 Movies, Sport and other programming genres. For each of these genres
programmes can be listed in start time order, e.g. "Movies" 81, "Sports" 82 or
"Events" 83. Programmes can also be listed by alphabetic order by title, e.g.
"Movies A-Z" 84, "Sports A-Z" 8~ or "Events A-Z" 86. Listings of new PPV
programmes of each genre are also available, e.g. "New Movies" 87, "New
1~ Sports" 88 or "New Events" 89.
Another menu item "Free Previews" 90, when selected, tunes the set
top box to a PPV barker channel which continuously promotes PPV
programming.
Figure 7 of the accompanying drawings shows an example of a Box
20 Office Movies listing screen 100. Within each Box Office listing screen a
section 101 of the screen area is dedicated to a video or still image used to
promote PPV programming. This promotion can continue whilst the
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26
subscriber is browsing through the listings or booking a PPV event. The
video or still image on the section 101 is switchable according to which title
is
selected from a menu 102 of pro~ammes in the lower half of the screen 100.
In Figure 7 the bar 103 for the movie "Die Hard IZ" is highlighted and a video
or still image representing that movie would be displayed in the section 101.
Thus, as the subscriber browses throu~.h the Box Office listings the
video/still
inset will change to denote the pro~amme selected - the video/still being a
trailer or promotion for the particular title.
In order to reduce bandwidth any video image is transmitted at a
reduced size and is scaled up to the required size by the set top box as
described in our aforementioned patent applications.
As a further advancement the video or still image is itself schedulable.
This enables the high bandwidth required for video promotions to be used to
neatest effect. For example, during the daytime PPV titles targeted at
families and children may be scheduled for video promotions. However, in
peak viewing time stills may be used to promote these events, and the video
promotions allocated to titles appealing to a more mature audience.
Other areas 104, 105 of the screen 100 are given over to the display of
a company and/or channel banner and text which may change depending on
which movie is highlighted in the menu 102. Icons 106 to 109 below the
menu 102 enable the user to select movie listings by movie type, e.g.
"Western" movies, "Action" movies", "Comedy" movies or "Classic" movies.
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Selection of one of the icons 106 to 109 causes the EPG to apply the
aforementioned filtering to the movie information before it is displayed on
the
screen 100.
Having thus described the present invention by reference to a preferred
S embodiment it is to be well understood that the embodiment in question is
exemplary only and that modifications and variations such as will occur to
those
possessed of appropriate lmowledge and skills may be made without departure
from the spirit and scope of the invention as set forth in the appended claims
and
equivalents thereof.
