Soft viterbi Reed-Solomon decoder
View Patent ↗A Viterbi decoder is used to provide erasure information to a symbol based decoder. In a preferred embodiment, a Viterbi decoder is used to provide either minimum distance path metric information or path probability information, which is summed over a symbol window to derive erasure information for the symbol based decoder.
1. A method of correcting errors in a digital signal, comprising the steps of:
receiving a signal;
finding minimum distance path metrics for symbols of the signal;
sorting the symbols by path metric minimum to find most probable symbols in error;
using the most probable symbols in error as erasure pointers to a symbol based error correction process.
2. The method of claim 1 , wherein the symbol based error correction process is a Reed-Solomon error correction process.
3. The method of claim 1 , wherein remaining code weight is used to find hard errors.
4. The method of claim 1 , further comprising the step of summing the minimum distance path metrics over a symbol window to find the path metric minimum.
5. The method of claim 1 , wherein the step of finding minimum distance path metrics further comprises finding the minimum distance path metrics with a Viterbi decoder prior to sorting the symbols by the path metric minimum.
6. The method of claim 1 , wherein the symbol based error correction process is based on the symbol width of the symbol window.
7. A method of correcting errors in a digital signal, comprising the steps of:
receiving a signal;
finding path probabilities for symbols of the signal;
summing the path probabilities over a symbol window:
sorting the symbols by path probability to find most probable symbols in error;
using the most probable symbols in error as erasure pointers to a symbol based error correction process.
8. The method of claim 7 , wherein the symbol based error correction process is a Reed-Solomon error correction process.
9. The method of claim 7 , wherein remaining code weight is used to find hard errors.
10. The method of claim 7 , wherein the step of finding the path probabilities further comprises finding the path probabilities with a Viterbi decoder.
11. The method of claim 7 , wherein the smallest values of the path probabilities in the symbol window are indicative of the most probable symbols in error.
12. The method of claim 7 , wherein the symbol based error correction process is based on the symbol width of the symbol window.
13. The method of claim 7 , wherein the path probabilities are in the form of a log likelihood ration (LLR).
14. A digital signal error correction system, comprising:
a digital channel;
a Viterbi decoder;
a symbol based decoder;
wherein the Viterbi decoder receives symbols transmitted over the digital channel and estimates likely error in the symbols to produce error estimates for each symbol;
wherein the error estimates are summed over a symbol window to produce most likely symbols in error; and
wherein the most likely symbols in error are used as erasures by the symbol based decoder.
15. The system of claim 14 , wherein the symbol based decoder is a Reed-Solomon decoder.
16. The system of claim 14 , wherein the error estimates are minimum distance path metrics.
17. The system of claim 14 , wherein the error estimates are path probabilities.
18. The system of claim 14 , wherein remaining code weight is used to find hard errors.
19. The system of claim 14 , further comprising a priority selector configured to generate the erasures.
20. The system of claim 14 , wherein the symbol based decoder is based on the symbol width of the symbol window.