Re: [Discuss-gnuradio] atsc signal plots
On Sat, May 06, 2006 at 10:16:15AM -0400, Chuck Swiger wrote: > On Fri, 2006-05-05 at 14:45 -0700, Matt Ettus wrote: > > > The 2.0 port isn't doing as well - a few eyes show up here > > > and there: > > > > > > http://webpages.charter.net/cswiger/g2_eq_data-1.jpg > > > > > Yep - looking at the 0.9 bit-timing-loop output: > > http://webpages.charter.net/cswiger/g09_btl_data-1.jpg > > vs a 2.x port of it shows something going wrong, using > the same input data: > > http://webpages.charter.net/cswiger/g2_btl_data-1.jpg > > could be something to do with differences in buffering, > scheduling, etc between gr0.9 and gr2.x. I think it's some kind of a porting error ;) Sorry, I can't get to it right now, but please ping me early next week if you haven't got it sorted out. Eric ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] atsc signal plots
On Fri, 2006-05-05 at 14:45 -0700, Matt Ettus wrote: > > The 2.0 port isn't doing as well - a few eyes show up here > > and there: > > > > http://webpages.charter.net/cswiger/g2_eq_data-1.jpg > > > > and that's with the NOP equalizer. The LMS eq is all noise > > all the time. > > To me it looks like the symbol timing tracker is not tracking properly. > As the sample time shifts relative to the correct sample time you come > in and out of alignment. As I recall, the equalizer comes after the > timing sync, so it won't work. It needs proper symbol timing, and > without it will actually make things worse. > Yep - looking at the 0.9 bit-timing-loop output: http://webpages.charter.net/cswiger/g09_btl_data-1.jpg vs a 2.x port of it shows something going wrong, using the same input data: http://webpages.charter.net/cswiger/g2_btl_data-1.jpg could be something to do with differences in buffering, scheduling, etc between gr0.9 and gr2.x. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] atsc signal plots
> The 2.0 port isn't doing as well - a few eyes show up here > and there: > > http://webpages.charter.net/cswiger/g2_eq_data-1.jpg > > and that's with the NOP equalizer. The LMS eq is all noise > all the time. To me it looks like the symbol timing tracker is not tracking properly. As the sample time shifts relative to the correct sample time you come in and out of alignment. As I recall, the equalizer comes after the timing sync, so it won't work. It needs proper symbol timing, and without it will actually make things worse. Matt ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] atsc signal plots
Here's some pictures for Friday - I though these were interesting, the output of the 0.9 atsc equalizer showing the 8 levels getting more distinct with every field: http://webpages.charter.net/cswiger/g09_eq_data-1.jpg Zooming in: http://webpages.charter.net/cswiger/g09_eq_data-2.jpg shows the field sync which is largely made up of only +5/-5, and zooming in on the beginning: http://webpages.charter.net/cswiger/g09_eq_data-3.jpg you can make out the +5 -5 -5 +5 segment sync, followed by the start of the pn511 pattern (7 -5's, +5, -5, then 8 +5's). The 2.0 port isn't doing as well - a few eyes show up here and there: http://webpages.charter.net/cswiger/g2_eq_data-1.jpg and that's with the NOP equalizer. The LMS eq is all noise all the time. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio