Calc_metric in digital_constellation_receiver

GNU Radio
#1

I want to use trellis codes along with generic_mod_demod.

  1. Can I replace the constellation_receiver object with a trellis_metric
    followed by a viterbi? If so is it required to have an operation
    equivalent
    to phase correction in constellation_receiver? How can I do that?

  2. There is a function for metric calculation inside
    constellation_receiver. Can I use it to implement viterbi?

Thanks in advance

#2

On Sun, Feb 24, 2013 at 6:36 AM, Manu T S [email protected] wrote:

I want to use trellis codes along with generic_mod_demod.

  1. Can I replace the constellation_receiver object with a trellis_metric
    followed by a viterbi? If so is it required to have an operation equivalent
    to phase correction in constellation_receiver? How can I do that?

constellation_receiver has four optional outputs. The fourth is a
phase-corrected complex number. You could use this as the input to
your metric calculation.

  1. There is a function for metric calculation inside constellation_receiver.
    Can I use it to implement viterbi?

This function is called by trellis.constellation_metrics_cf which
generates metrics that you can feed into the viterbi block. Metrics
are calculated for every constellation point, so for large
constellations the efficiency will be appalling.