WJCE6355 Intel, WJCE6355 Datasheet - Page 11

• Manufacturer Part Number: WJCE6355
• Description: Demodulator 64-Pin LQFP
• Manufacturer: Intel

Specifications of WJCE6355

• Package: 64LQFP
• Operating Temperature: -40 to 85 °C

CE6355
Data Sheet
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Functional Description
A functional block diagram of the CE6355 OFDM demodulator is shown in Figure 4. This accepts an IF analogue signal and
delivers a stream of demodulated soft decision data to the on-chip Viterbi decoder. Clock, timing and frequency synchroni-
zation operations are all digital and there are no analogue control loops except the AGC. The frequency capture range is
large enough for all practical applications. This demodulator has novel algorithms to combat impulse noise as well as
co-channel and adjacent channel interference. If the modulation is hierarchical, the OFDM outputs both high and low
priority data streams. Only one of these streams is FEC-decoded, but the FEC can be switched from one stream to another
with minimal interruption to the transport stream.
Figure 4 - OFDM Demodulator Diagram
The FEC module shown in Figure 5 consists of a concatenated convolutional (Viterbi) and Reed-Solomon decoder
separated by a depth-12 convolutional de-interleaver. The Viterbi decoder operates on 5-bit soft decisions to provide the
best performance over a wide range of channel conditions. The trace-back depth of 128 ensures minimum loss of perfor-
mance due to inevitable survivor truncation, especially at high code rates. Both the Viterbi and Reed-Solomon decoders
are equipped with bit-error monitors. The former provides the bit error rate (BER) at the OFDM output. The latter is the
more useful measure as it gives the Viterbi output BER. The error collecting intervals of these are programmable over a
very wide range.
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Intel Corporation