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AR# 22254

LogiCORE Reed Solomon Decoder - How do I set up the Reed Solomon Decoder for continuous block processing?


Keywords: delay, rs decoder

How do I set up the Reed Solomon Decoder for continuous block processing?


The ability to perform continuous block processing is dependent on the latency of the core. The latency is always measured in symbol periods.

Latency = the number of sampled symbols from a symbol that is sampled on DATA_IN to the corrected version of that symbol appearing on DATA_OUT.
Latency = n + m + processing delay + c

For some parameter selections, the decoder might not be ready to accept one code block immediately after another because it is still processing the first block.

The processing delay formula is provided in the Reed Solomon Decoder data sheet. For a fixed "n" Reed Solomon decoder, the processing delay is the minimum number of symbol periods from the start of the first symbol period of a code block to before another code block can be started.

Note that for a processing delay greater than "n" (total number of symbols in a code block), it is not possible to follow one code block immediately with another.

Note that the variable "n" decoder can still accept a new code block, even if the processing delay is greater than "n", due to its internal buffering.

However, if new blocks are continually fed to the decoder with "n" greater than the processing delay, at some point it will be unable to accept a new code block.

The processing delay can be reduced by increasing the number of clock periods per symbol.

Please see (Xilinx Answer 30176) for a detailed list of LogiCORE Reed Solomon Decoder Release Notes and Known Issues.
AR# 22254
Date 05/13/2009
Status Archive
Type General Article
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