ViewSonic N4251w-1M, Service Manual

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C. DTV and HDMI.
MT5112 is a fully integrated single-chip 8-VSB and 64/256-QAM demodulator. The chip is
designed specifically for the digital terrestrial HDTV and CATV receivers
.
MT5112 includes a
10-bit A/D converter, 8-VSB/QAM demodulator, TCM (Trellis-Coded modulation) decoder,
and Reed- Solomon Forward Error Correction decoder. Moreover, an internal controller
handles the acquisition and tracking to ensure the best receiving performance.
The internal controller communicates with the external host controller via the I2C-compatible
interface, and also provides direct control to the RF tuner via the second I2C-compatible
interface.
MT5112 accepts either the direct IF signals and the IF signals are sampled by a 10-bit A/D
converter. Afterward, the digitized samples are further processed for adjacent channel
interference rejection. MT5112 measures the power level of the digitized sequence, and feeds
the control voltages back to the RF tuner and the IF amplifier respectively. The control
voltages are converted to analog signals through the on-chip 1-bit sigma-delta D/A converters
plus the off-chip R-C low-pass filters. The automatic gain control keeps the received power
level at a desired level and maximizes the received SNR.
The MT5351AG is a DTV Backend Decoder SOC which support flexible transport demux,
HD MPEG-2 video decoder, JPEG decoder, MPEG1,2, MP3, AC3 audio decoder, HD TV
encoder. It incorporates a processor for system control. The processor issues instructions to
control the peripheral via I²C and communicates with MT8202 via UART. DDR SDRAM is
externally connected to the MT5351AG, the unified memory allows all internal decoders can
share data,which reduces external memory types and capacities.
The MT5351AG receives bitstream input in TS format, and then separates the TS into audio
and video PES, analyzing the PES header, and transferring the PES to the audio and video
decoders.
MT8293 is fully HDMI-compliant receiver that fits directly into home theater products such as
LCD TVs, plasma TVs and HDTVs. The receiver is capable of supporting bandwidths up to
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