Demodulator

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A Demodulator (short Demod) recovers (demodulates) the original information from the received and downconverted RF signal -- a tuner acquires the RF signal and converts it to an intermediate frequency (IF) which is then passed onto the demodulator for processing. The type of demodulator IC used for this task of information recovery is specific and dependent upon the nature of the signal transmission scheme involved.

In the case of analog TV, the IF inputted into the demodulator contains the composite signal that was originally modulated onto the RF carrier. After recovery, the demodulator outputs a CVSB signal, which will then need to be digitized through sampling techniques performed by a A/V decoder.

In the case of digital TV transmission schemes, the IF inputted into the demodulator contains a MPEG2 Transport Stream (TS) that was originally modulated onto the RF carrier. In the process of recovering that TS, digital demodulators will perform Forward Error Correction (Convolutional Viterbi- and Block-Reed-Solomon-Decoding). This whole process is sometimes referred to as RF-to-bits, for, unlike the case with analog IF demodulators, the recovered signal outputted from the digital demodulator is already a digital bit stream; specifically a TS. The TS will in turn be sent to a decoder in order to display (and, depending upon what format the underlying video content contained within the TS was encoded with, this could be a MPEG2 or MPEG4 decoder ... and either hardware or software based).

Demodulator Chipsets

Analogue IF Demodulators

A Sortable List of Analog IF Demodulators
Vendor Model Standards Linux Support Comments
Philips TDA9887 NTSC Yes -
Xceiev XC3028 NTSC, PAL er, somewhat firmware galore

... an so on ...

Digital Demodulators

A Sortable List of Digital Demodulators
Vendor Model Standard Linux Support Comments
ATI/AMD Nxt2000 ATSC  ? Supports 8-VSB, QAM; firmware required
ATI/AMD Nxt2002 ATSC yes Supports 8-VSB, QAM; firmware required
ATI/AMD Nxt2004 ATSC yes Supports 8-VSB, QAM; firmware required
ATI/AMD Theater 31x ATSC no Supports 8-VSB, QAM

...and so on ...

Note: Info below needs to be added to table above
  • LG DT3302
  • LG DT3303
  • Oren
  • Oren
  • Samsung s5h
  • Zoran/Oren Cascade

....

DVB-T Demodulators

...

DVB-S2 Demodulators

...


Some Examples for Digital Demods are
Model Type and Vendor
NXT6000 DVB-T/COFDM Demod produced by ATI
AT76C651 DVB-C/QAM Demod produced by Atmel Corporation
CX22700 DVB-T/COFDM Demod produced by Conexant Systems, Inc.
CX24110 DVB-S/QPSK Demod produced by Conexant Systems, Inc.
DIB3000M DVB-T/COFDM Demod produced by DiBcom
L64781 DVB-T/COFDM Demod produced by LSI Logic Corporation
L64782 DVB-T/COFDM Demod produced by LSI Logic Corporation
MT8872/SP8872 DVB-T/COFDM Demod produced by Microtune/SPaSE
TDA10021 DVB-C/QAM Demod produced by Philips Semiconductors
TDA10045 DVB-T/COFDM Demod produced by Philips Semiconductors
TDA10046 DVB-T/COFDM Demod produced by Philips Semiconductors
TDA8083 DVB-S/QPSK Demod produced by Philips Semiconductors
SP8870 DVB-T/COFDM Demod produced by SPaSE
STV0297 DVB-C/QAM Demod produced by STMicroelectronics
STV0299 DVB-S/QPSK Demod produced by STMicroelectronics
VES1893 DVB-S/QPSK Demod produced by VLSI Technology
VES1993 DVB-S/QPSK Demod produced by VLSI Technology
VES1820 DVB-C/QAM Demod produced by VLSI Technology
MT312 DVB-S/DSS/QPSK Demod produced by Zarlink Semiconductor
MT352 DVB-S/DSS/QPSK Demod produced by Zarlink Semiconductor
ZL10312 DVB-S/DSS/QPSK Demod produced by Zarlink Semiconductor
ZL10313 DVB-S/DSS/QPSK Demod produced by Zarlink Semiconductor