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Data BroadcastingData Broadcasting

Ken McCannKen McCann

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Application Example - Internet via satelliteApplication Example - Internet via satellite

ServiceProvider

SatelliteOperator

InformationProvider

User PC

DVB Card

18" dish

Leased line

The Net

Delivery of web pagesat up to 38 Mbit/s

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DVB Return ChannelDVB Return Channel

Return channel used for interactive Return channel used for interactive services depends on the physical network, services depends on the physical network, e.g.:e.g.:

• Telecom modem via PSTN & ISDN for Telecom modem via PSTN & ISDN for terrestrial or satellite TVterrestrial or satellite TV

• DVB/DAVIC modem for cable TVDVB/DAVIC modem for cable TV

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DVB Data BroadcastingDVB Data Broadcasting

DVB Data Broadcasting standard, EN 301 192, DVB Data Broadcasting standard, EN 301 192, provides a set of network-independent provides a set of network-independent protocols optimised to different applications:protocols optimised to different applications:

• data pipingdata piping• data streamingdata streaming• multiprotocol encapsulationmultiprotocol encapsulation• data carouseldata carousel• object carouselobject carousel

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DVB Data PipingDVB Data Piping

DVB Data Piping uses MPEG Transport DVB Data Piping uses MPEG Transport Stream (TS) packets without any intermediate Stream (TS) packets without any intermediate layerlayer

• provides non-synchronised end-to-end provides non-synchronised end-to-end delivery of data through DVB networksdelivery of data through DVB networks

• 188 byte packets with 184 byte payload188 byte packets with 184 byte payload• DVB descriptor to identify data pipeDVB descriptor to identify data pipe• Any other mechanism relies on the Any other mechanism relies on the

applicationapplication

1 0 1 1 0 0 1 0 1 10 1 0 0 1 1 0 0 1 0

0 1 0 0 1 1 0 0 1 0

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DVB Data StreamingDVB Data Streaming

Based on the MPEG Packetised Elementary Stream Based on the MPEG Packetised Elementary Stream (PES) construct that is used for video and audio:(PES) construct that is used for video and audio:

• AsynchronousAsynchronous data streams carry no timing data streams carry no timing information (e.g. RS232)information (e.g. RS232)

• SynchronousSynchronous data streams allow clock and data data streams allow clock and data to be regenerated (e.g. E1, T1)to be regenerated (e.g. E1, T1)

• SynchronisedSynchronised data streams allow playback in data streams allow playback in sync. with video and audiosync. with video and audio

Data

Audio

Video

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Multiprotocol Encapsulation Multiprotocol Encapsulation

Based on the MPEG section construct that is Based on the MPEG section construct that is used for MPEG PSI and DVB SI:used for MPEG PSI and DVB SI:

• optimised for Internet Protocol (IP) but optimised for Internet Protocol (IP) but can be used for any other network can be used for any other network protocolprotocol

• ““datagrams” can be fragmented into datagrams” can be fragmented into multiple sections if they exceed multiple sections if they exceed maximum payload of a single section maximum payload of a single section (4080 bytes)(4080 bytes)

TCP/IP

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Data Carousel Data Carousel

Based on the MPEG Digital Storage Media Based on the MPEG Digital Storage Media Command and Control (DSMCC) data carouselCommand and Control (DSMCC) data carousel

• supports cyclic transmission of data supports cyclic transmission of data modules to receiversmodules to receivers

• analogous to traditional Teletextanalogous to traditional Teletext• data is structured into Modules, Groups data is structured into Modules, Groups

and SuperGroupsand SuperGroups• could be used for software download to could be used for software download to

receiversreceivers

.dll.dll

.doc

.pic

.xls

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Object Carousel Object Carousel

Based on the MPEG DSMCC object carouselBased on the MPEG DSMCC object carousel• supports cyclic transmission of structured supports cyclic transmission of structured

groups of objects from broadcast server to groups of objects from broadcast server to client (receiver)client (receiver)

• can download application, data files, data can download application, data files, data streams and trigger eventsstreams and trigger events

• typically used to provide interactive typically used to provide interactive servicesservices

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ConclusionsConclusions

• DVB data broadcasting specification DVB data broadcasting specification provides a comprehensive set of provides a comprehensive set of network-independent protocolsnetwork-independent protocols

• capacity for data broadcasting can be capacity for data broadcasting can be traded against capacity for video and traded against capacity for video and audio in a totally flexible manneraudio in a totally flexible manner