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Data Broadcasting

Ken McCann

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Application Example - Internet via satellite

ServiceProvider

SatelliteOperator

InformationProvider

User PC

DVB Card

18" dish

Leased line

The Net

Delivery of web pages

at up to 38 Mbit/s

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DVB Return Channel

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

Telecom modem via PSTN & ISDN forterrestrial or satellite TV

DVB/DAVIC modem for cable TV

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DVB Data Broadcasting

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

data piping data streaming

multiprotocol encapsulation

data carousel object carousel

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DVB Data Piping

DVB Data Piping uses MPEG TransportStream (TS) packets without any intermediatelayer

provides non-synchronised end-to-enddelivery of data through DVB networks

188 byte packets with 184 byte payload

DVB descriptor to identify data pipe

Any other mechanism relies on theapplication

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 Streaming

Based on the MPEG Packetised Elementary Stream

(PES) construct that is used for video and audio:

Asynchronous data streams carry no timing

information (e.g. RS232)

Synchronous data streams allow clock and data

to be regenerated (e.g. E1, T1)

Synchronised data streams allow playback insync. with video and audio

Data

Audio

Video

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Multiprotocol Encapsulation

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

optimised for Internet Protocol (IP) but

can be used for any other networkprotocol

datagrams can be fragmented into

multiple sections if they exceed

maximum payload of a single section(4080 bytes)

TCP/ IP

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Data Carousel

Based on the MPEG Digital Storage MediaCommand and Control (DSMCC) data carousel

supports cyclic transmission of data

modules to receivers analogous to traditional Teletext

data is structured into Modules, Groupsand SuperGroups

could be used for software download to

receivers

.dll.dll

.doc

.pic

.xls

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Object Carousel

Based on the MPEG DSMCC object carousel

supports cyclic transmission of structuredgroups of objects from broadcast server to

client (receiver) can download application, data files, data

streams and trigger events

typically used to provide interactiveservices

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Conclusions

DVB data broadcasting specificationprovides a comprehensive set ofnetwork-independent protocols

capacity for data broadcasting can betraded against capacity for video andaudio in a totally flexible manner