Technology of Q 2500 colour TV set
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Technology of Q 2500 colour TV set

Technology of Q 2500 colour TV set Technology of Q 2500 colour TV set

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Technology of Q 2500 colour TV set3.4.4 DVB demodulation and fault correctionAdditional signal processing comprises:- AD conversion of the quadrature signalsfrom the tuner,- QPSK demodulation andchannel decoding in the form of ForwardError Correction.Demodulation and channel decoding arecompatible with ETS 300 421. In practice anin-house chip solution is used for all threefunctions. For reasons of interface compatibilitywith the MPEG decoder, the STV0299Bmodule from ST Microelectronics is used.There then follows specification of the practicalimplementation, as well as parameters,which in ETS 300421 are only partially set.Document Q 2500 56 © Loewe ProCollege

Technology of Q 2500 colour TV setParameter Value/algorithm NotesChip STV0299B Manufacturer: ST MicroelectronicsADCADC-TypeResolutionSampling ClockIQ input voltageDemodulationProcedureSymbol rate range STV0299BSymbol rate over all (includingtuner) without neighbouringchannel assignmentSymbol rate over all withneighbouring channel assignmentDual2*6 bitVariable, dependent on symbolrate1 VssGenerated by on chip PLLCoherent grey coded QPSKdemodulation1...45 Mbaud1...30 Mbaud Lower limit: Phase noise oftunerUpper limit: IF bandwidth oftuner15...30 MbaudPreferred value for symbol rate 27.5 and 22 Mbaud Used in frequency search procedureOther symbol ratesDecoding from NIT (deliverysystem descriptor) of BarkerChannel or manual selectionRoll off filteringHalf NyquistRoll off factor 0.20 (20 %); 0.35 (0.35 %)Used roll off factor 0.35 (35 %)Carrier recoveryDigital PLL with internal derotatorand hardware lock-indetectorPulse recoveryProcessing of the normal orinverting spectrumInternal digital PLLDocument Q 2500 57 © Loewe ProCollege

<strong>Technology</strong> <strong>of</strong> Q <strong>2500</strong> <strong>colour</strong> <strong>TV</strong> <strong>set</strong>3.4.4 DVB demodulation and fault correctionAdditional signal processing comprises:- AD conversion <strong>of</strong> the quadrature signalsfrom the tuner,- QPSK demodulation andchannel decoding in the form <strong>of</strong> ForwardError Correction.Demodulation and channel decoding arecompatible with ETS 300 421. In practice anin-house chip solution is used for all threefunctions. For reasons <strong>of</strong> interface compatibilitywith the MPEG decoder, the S<strong>TV</strong>0299Bmodule from ST Microelectronics is used.There then follows specification <strong>of</strong> the practicalimplementation, as well as parameters,which in ETS 300421 are only partially <strong>set</strong>.Document Q <strong>2500</strong> 56 © Loewe ProCollege

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