Viterbi IP Core User Guide

ID 683280
Date 11/06/2017
Public
Document Table of Contents

3.4.3. Viterbi Parameters

Parameter Value Description
Maximum constraint length (LMAX)

5 to 9 (hybrid)

3 to 9 (parallel)

The maximum constraint length LMAX. .
ACS Units (A) 1, 2, 4, 8, or 16 The number of ACS units, which adds a degree of parallelism (hybrid architecture only). The range of values available depends upon the value of maximum constraint length LMAX.
Traceback (v) 8 (minimum) The traceback length, which is the number of stages in the trellis that are traced back to obtain a decoded bit. It is typically set to 6 × L for unpunctured codes, and up to 15 × L for highly punctured codes.
Softbits (softbits) 1 to 16 The number of soft decision bits per symbol. When softbits is set to 1 bit, the decoder acts as a hard decision decoder, and still allows for erased symbols to be entered using the eras_sym input.
Bmgwide The precision of the state metric accumulation. The parameter editor selects and displays the optimum value, which depends on NMAX, LMAX and, softbits.