TDA8980 Philips Semiconductors, TDA8980 Datasheet - Page 3

• Manufacturer Part Number: TDA8980
• Description: ATSC/NTSC digital TV front-end chipset
• Manufacturer: Philips Semiconductors

8-VSB demodulator
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Adaptive equalizer
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On-chip FEC
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The TDA8961 is an ATSC-compliant device with forward error
correction, accepting 8-VSB modulated signals with the additional
ability to apply the VSB IC AGC control output directly to the
tuner. The combination of the TDA8980 and TDA8961 requires
only one 12 MHz crystal and when the TDA8980 is performing
NTSC decoding, the TDA8961 can be set in a feed-through mode,
enabling ITU656 data to appear at the MPEG2 transport stream
output for feeding to the graphics display IC. The demodulator can
also act as an MPEG2 Transport Stream switcher for an additional
serial stream.
After the TDA8961 has performed internal carrier recovery, Nyquist
filtering and symbol timing recovery, it carries out adaptive
equalization using the ATSC field sync (trained equalization)
and/or the 8-VSB data itself (blind equalization). This uses a decision
On-chip digital tuner AGC control
Integrated digital Square-Root Raised-Cosine (half Nyquist)
filter with 11.5 % roll-off
Fully internal carrier recovery loop with programmable
loop filter
No need for external VCXO and DAC due to internal sample
rate converter
Fully internal symbol timing recovery with programmable
loop filters
Feed forward including a decision feedback equalizer (DFE)
Standard range: -2.3 s to +22.5 s (up to 80 s in conjunction
with external software)
Adaptation based on ATSC field sync (trained) and/or
8-VSB data (blind)
Additional complex equaliser to cope with highly dense
urban multipath
Patented adaptive NTSC co-channel filter technology,
with low/zero insertion loss
Trellis (Viterbi) decoder
Rate 2/3 (Rate 1/2 Ungerboeck-code-based)
(207, 187, T=10) Reed-Solomon decoder
Internal convolutional de-interleaving
ATSC standard-based de-randomizer
feedback equalizer (DFE) structure.
Once trellis decoding is complete, the stream
is de-interleaved with a convolutional
de-interleaver with on-chip memory.
The Reed-Solomon decoder is ATSC-
compliant, with a length of 207, and it can
correct up to 10 bytes. After the decoded
stream is de-randomized using a pseudo-
random bit sequence (PRBS), it outputs an
8-bit parallel or a serial MPEG2 transport
stream for subsequent de-multiplexing.
TD1536 tuner
Able to handle ATSC terrestrial signals as well
as NTSC and QAM, the TD1536 offers flat
frequency response, low oscillator phase noise
and excellent large signal handling
characteristics. Optimized for handling high
adjacent channel levels, through on-board
selectivity adjustment (SAW filter), the
TD1536 also provides internal automatic gain
control (AGC), minimizing design-in effort.
The TD1536’s low output impedance makes
it capable of driving several SAW filters
(for example, second VSB and NTSC SAWs).
It is powered from a single 5V supply.
SAA7146A PCI bridge
For PC/multimedia applications, the reference
design includes the option to include the
SAA7146A PCI bridge. This device features
high performance 2D scaling, resulting in very
few artefacts even when pictures are reduced to
icon size, making it ideal for windowing and
high-end applications. It also has a hardware
vanity picture function and by performing
most of the video processing on-board, the
SAA7146A helps reduce load on the CPU,
maintaining high overall system performance.
In addition to the PCI-bus, it supports a
variety of interfaces including two ITU-R 656
ports, an Intel/Motorola 8/16-bit DEBI
(Digital Expansion Bus Interface), I
bus connectors, and a 4-bit general purpose
interface.
2
C and I
2
S