Just wanted to add that if you choose option four, ie you have at the output of the constellation_receiver a phase-corrected complex stream then you can use it directly as the input to the viterbi_combined block so that you avoid the use of the trellis.constellation_metrics_cf block. Achilleas Date: Sun, 24 Feb 2013 12:28:07 -0700 From: Ben Reynwar <firstname.lastname@example.org> To: Manu T S <email@example.com> Cc: GNURadio Discussion List <firstname.lastname@example.org> Subject: Re: [Discuss-gnuradio] calc_metric in digital_constellation_receiver Message-ID: <CAHXOypq4nJ7jDf_txTkRdTVakG--FZ9aSpBU2nMyuLCq+Zqx3g@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 On Sun, Feb 24, 2013 at 6:36 AM, Manu T S <email@example.com> 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. > > 2. 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.
on 2013-02-25 18:37