Altera Reed-Solomon Compiler - Manual (Page 31)

December 2014 Altera Corporation Reed-Solomon Compiler
User Guide
A. Using the RS Encoder or Decoder in a
CCSDS System
The Reed-Solomon (RS) encoder or decoder MegaCore functions work in canonical
base (otherwise known as conventional base). This base can cause confusion when
trying to implement the RS encoder or decoder directly into a dual-base system, for
example, when working with the Consultative Committee for Space Data Systems
(CCSDS) standard.
To transfer from a canonical-base to a dual-base system, a Berlekamp transform is
used, which you need to implement in logic.
Figure A–1 shows an example use of the
Berlekamp transform.
Supplying Test Patterns
If you are working with a dual-base system, for example, CCSDS, and wish to supply
the RS encoder or decoder with some test patterns from the dual-base system, follow
these steps:
1. Apply the Berlekamp transform (dual to canonical) to the test pattern.
2. Apply the test pattern to RS encoder or decoder.
3. Apply the Berlekamp transform (canonical to dual) to the encoder output.
4. Check the test pattern.
f
For more information about implementing the transformation function, refer to
Annex B of the standard specification document CCSDS-101.0-B-5 at
www.ccsds.org .
Figure A–1. Using the Berlekamp Transform
RS Encoder
Berlekamp
Transform
(Canonical to Dual)
Pre-transform
(Dual to Canonical)
Post-transform
(Canonical to Dual)
Berlekamp
Transform
(Dual to Canonical)
Channel
RS Decoder