Altera Viterbi Compiler - Manual (Page 26)

Parameter Value Description
BER On or Off Specifies the BER estimator
option, refer to “BER Estimator”
on page 3–7.
Node Sync On or Off Specifies the node synchroniza‐
tion option (only available when
BER option is on).
Optimizations None, Continuous, or Block Specifies the optimization for the
parallel decoder. if you select
None you can turn on Best State
Finder. However, to use less
logic, turn off Best State Finder.
BER Estimator
The BER estimator option uses a re-encode and compare approach for estimating the number of errors in
the input data.
Figure 3-7: BER Block Diagram
Viterbi
Decoder
Input Symbols
Delay
Compare
and Count
BER Output
(numerr)
Convolutional
Encoder
In cases where the signal-to-noise ratio is sufficiently high to allow the decoder to decode an error-free
output, the BER estimation is very close to the actual channel BER. When the decoder is not decoding an
error-free output, the estimated BER is higher and more random than the actual channel BER, which
introduces a degree of uncertainty directly proportional to the output errors.
Note: For a TCM code, the BER block does not produce a meaningful output (
numerr
) because the BER
block does not compute errors at the input for TCM codes.
3-8 BER Estimator
UG-VITERBI
2014.12.15
Altera Corporation Viterbi IP Core Functional Description
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