Re: Symbol timing estimator block and CPM modulations

[Alex Roberts]

Copy that. Would a preamble with better properties like a gold code allow to raise that threshold? I guess I need to dig into what that threshold means. On the examples I’ve seen it’s always 0.9 or higher.

On Monday, June 29, 2020, Andy Walls <andy@silverblocksystems.net> wrote:
> On Sun, 2020-06-28 at 16:31 -0500, Alex Roberts wrote:
> > Andy, 
> > 
> > I had a copy of an old flowgraph that you posted on the mailing list
> > a long while back (
> > https://lists.gnu.org/archive/html/discuss-gnuradio/2016-03/msg00735.html
> > ). This is what initially confused me on what to pass in as gmsk
> > symbols to corr_est block as it has strictly real values.
> > 
> > I modified it to mux in the preamble that's in the octave code with a
> > random source. I also modified the octave code to match the samples
> > per symbol of the flowgraph (10) and generated the modulated symbols
> > for the corr_est block. The corr_est block does indeed
> > perform conjugation and reversal of the symbols, so I used the "h_iq"
> > value from the octave code as the modulated symbols since it has not
> > been conjugated or reversed. I'm not getting corr_est tags. 
>
> On that flowgraph, set your threshold on the corr_est block to 0.23.
>
> BTW, that preamble has horrible correlation properties.
>
>
> > Thanks,Alex.
>
> -Andy