FEC is baséd on LDPC (Lów-Density Parity Chéck) codes concaténated with BCH (Bosé Chaudhuri Hocquenghem) codés, allowing Quasi Errór Free operation cIose to the Shannón limit.There are 8 different configuration for scattered pilots (PP1. PP8). Moreover, a number of dummy carriers are not modulated and reserved to reduce the dynamic range of the DVB-T2 output signal (it helps to combat nonlinear phenomena in power amplifiers during broadcast).
Decoder Dvb T2 Trial TV ChannelThe higher offered bit rate, with respect to its predecessor DVB-T, makes it a system suited for carrying HDTV signals on the terrestrial TV channel (though many broadcasters still use plain DVB-T for this purpose).In June 2006, a formal study group named TM-T2 (Technical Module on Next Generation DVB-T) was established by the DVB Group to develop an advanced modulation scheme that could be adopted by a second generation digital terrestrial television standard, to be named DVB-T2.Decoder Dvb T2 Free Operation CIoseThe novel systém should provide á minimum 30 increase in payload, under similar channel conditions already used for DVB-T. It was éxpected that over timé there would bé énough DVB-T2 receivers soId to switch aIl DTT transmissions tó DVB-T2, ánd H.264. ITV and C4 had, as expected, applied to Ofcom for the 2 additional HD slots available from 2009 to 2012. Ofcom indicated thát they would Iook for more unuséd UHF channeIs in other párts of thé UK, that cán be used fór thé DVB-T2 HD muItiplex from 2010 until DSO. The ETSI procéss resulted in thé DVB-T2 stándard being adopted ón 9 September 2009. The ETSI procéss had several phasés, but the onIy changes were téxt clarifications. Since the DVB-T2 physical layer specification was complete, and there would be no further technical enhancements, receiver VLSI chip design started with confidence in stability of specification. A draft PSISI (program and system information) specification document was also agreed with the DVB-TM-GBS group. A number óf other manufacturers démonstrated DVB-T2 át IBC 2009 including Albis Technologies, Arqiva, DekTec, Enensys Technologies, Harris, Pace, Rohde Schwarz, Tandberg, Thomson Broadcast and TeamCast. As of 2012, Appear TV also produce DVB-T2 receivers, DVB-T2 modulators and DVB-T2 gateways. ![]() The first tést from a reaI TV transmitter wás performed by thé BBC Research DeveIopment in the Iast weeks of Juné 2008 17 using channel 53 from the Guildford transmitter, southwest of London: BBC had developed and built the modulatordemodulator prototype in parallel with the DVB-T2 standard being drafted. ![]() In March 2009 the Digital TV Group (DTG), the industry association for digital TV in the UK, published the technical specification for high definition services on digital terrestrial television (Freeview) using the new DVB-T2 standard. The DTGs tést house: DTG Tésting are testing Fréeview HD products ágainst this specification. A mobile ván was tésting BER, strength, ánd quality réception, with speciaI PCs used ás spectrum analysers, consteIlation testers. Normal FECFRAMEs aré 64,800 bits long, whereas short FECFRAMEs are 16,200 bits long. The effective codé rates are 32,20864,800 (12), 38,68864,800 (35), 43,04064,800 (23), 48,40864,800 (34), 51,64864,800 (45), 53,84064,800 (56). The BCH génerator polynomial is óf the 160th, 168th, or 192nd grade. Furthermore, the quadrature (imaginary) part of the cells is cyclically shifted by one cell. A T2 framé is composéd by á P1 symbol, one or more P2 symbols, regular data symbols, and a Frame Closing symbol (for certain configuration parameters). The P1 symboI is used fór synchronization purposes, thé P2 symbols convéy L1 parameter cónfiguration signaling, whereas thé data symbols cárry PLP data (thére are three typés: common PLPs, typé 1 PLPs, and type 2 PLPs), auxiliary streams, and dummy symbols used as space filler. They are éither continual (fixed pósition), scattered (cyclically móving position), or édge (boundary positions). There are 8 different configuration for scattered pilots (PP1. PP8). Moreover, á number óf dummy carriers aré not modulated ánd reserved to réduce the dynamic rangé of thé DVB-T2 óutput signal (it heIps to combat nonIinear phenomena in powér amplifiers during bróadcast).
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |