L64767 LSI Logic Corporation, L64767 Datasheet - Page 7

• Manufacturer Part Number: L64767
• Description: Smatv Qam Encoder
• Manufacturer: LSI Logic Corporation

Sync/Error Flag Inserter and Scrambler
Reed-Solomon Encoder
Convolutional Interleaver
After initialization, both pointers run independently. The frequency
relationship of OCLK to ICLK determines how the read and write pointers
advance. The L64767 asserts its FIFOALARM pin whenever the two
pointers are equal. This information is also available through a
FIFO_ALARM_STORE bit.
By specifying the sync insertion mode, you can instruct the sync inserter
to insert sync bytes into the data stream. Sync insertion minimizes bit
errors in sync bytes (even if sync is already inserted in the stream). If
sync bytes are contained in the bit stream and are used for synchro-
nization of the device, regenerated sync bytes conceal single errors in
the sync pattern.
When an uncorrectable error has occurred (ERRORIN signal is HIGH),
the L64767 sets both the MPEG-2 transport_error_indicator bit in the
packet (the most significant bit of the second byte in a packet) and
ERF_STORE. You can use ERF_STORE to check if an error has
occurred. You can also configure the L64767 to issue an interrupt for
these errors or continue processing without an interrupt.
The scrambler module performs energy dispersion of the data stream.
This module operates in parallel mode. For a complete description of the
functional characteristics of this module refer to the standards document
DTVB1190/DTVC37, Revision 3 .
Reed-Solomon (RS) codes aid in error correction by using redundant
check symbols in its code words. RS error correction codes are
systematic and operate on bytes rather than single-bit data streams. RS
codes are expressed, by convention, as two numbers. The first indicates
the total code word length (N). The second indicates the number of
message bytes (K). The difference between these two numbers (N – K)
is the number of check bytes.
The interleaver rearranges the ordering of a sequence of symbols in a
deterministic manner. Since the interleaver is convolutional, it requires
less memory than the conventional RAM-intensive block type interleavers.
L64767 SMATV QAM Encoder
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