L64724 LSI Logic Corporation, L64724 Datasheet - Page 182

• Manufacturer Part Number: L64724
• Description: Satellite Receiver
• Manufacturer: LSI Logic Corporation

7.3.1.2 Reed-Solomon ERROR Correction Codes
7-12
Figure 7.7
A code word is a block of N bytes that includes K message symbols and
N – K check bytes (R.) The check bytes or symbols are some fraction of
the message symbols. A large number of check symbols allows the
decoder to correct a large number of transmission errors.
The redundant check symbols in a message allow a decoder at the
receiving end of a transmission line to detect transmission errors and
reconstruct the original message content.
diagram of the basic encoder and decoder functions in a transmission
system.
Figure 7.8
Message
After generating a code word, the encoder transmits it through a low cost
channel to a decoder. The decoder compares the bit stream in the
message data to the encoding in the check bytes to detect transmission
errors. The original message can be precisely reconstructed from the
check symbols, as long as the number of symbol errors in the code word
is less than or equal to R/2.
Reed-Solomon (RS) error correction codes are systematic and operate
on bytes rather than single-bit data streams. They are especially good in
burst error applications The importance of RS codes is illustrated by their
adoption as international and domestic standards in various areas of
The FEC Decoder Pipeline
Data
Code Word Structure
FEC Data Path
Encoder
Message + Check Bytes = Code Word
K Message Bytes
Code Word
N Code Word Bytes
Channel
Check Bytes = Message
Figure 7.8
Decoder
R Redundant Check Bytes
shows a block
Corrected
Message
Data