>From Marcus: > ... and that (wut) might be a bug, because it implies that, if the stream has > both a time tag and a sob tag, the > question whether the tx metadata has a time tag depends on in which order > these tags are sorted on the the > tag storage multimap. Which might be random, because tags are sorted only by > tag offset. > @Martin: is there a reason that this is explicitely set to false here, or can > one just fix this by deleting a line?
This appears to be handled correctly. Given the same tag offset, the order of tx_time vs. tx_sob tags should not matter. If tx_time is found first, it sets found_time_tag=true and _metadata.has_time_spec=true (lines 652 & 653). Then _metadata.has_time_spec is overwritten in the tx_sob check (line 665) with 'false', but is set back to 'true' in line 743 due to found_time_tag being true. if (found_time_tag) { _metadata.has_time_spec = true; } If instead tx_sob is found first and tx_time second, then the time spec will also be set in line 743. So the question is whether setting _metadata.has_time_spec=false is really necessary. I'd say it's worth keeping in case the user doesn't always want to use tx_time stamps. The user may want to schedule some bursts but force others to transmit as soon as possible while still using the ATR functionality of the USRP. I know all this logic can be hard to follow, but it has to handle so many different cases and possibly span many calls to work and tag_work. >From Frederik: > Unfortunately, even with the newest version the USRP is still transmitting > its carrier over the air. I tried both with > the Message Burst Source as well as with the Stream to Tagged Stream Block > combined with setting a Length Tag > name in the USRP Sink. With the Tag Debug Block I see tx_sob+tx_eob and the > Length Tag, respectively. They all > seem to be at the right place and have the right value. > > The Length Tag should arrive properly at the Sink. I checked by changing the > tag's name at the Stream to Tagged > Stream Block to something stupid and finally got an "tG" printed out. It should be mentioned that there are two burst tag interfaces that cannot be mixed. if a Length Tag Name is specified to the constructor, all tx_sob and tx_eob tags will be ignored in tag_work to ensure the interfaces are mutually exclusive. If no Length Tag Name is specified, then tag_work will search for tx_sob/tx_eob tags and won't look for length tags. Sean On 21.10.2014 15:53, Frederik Wing wrote: > Hi Marcus, >>>> I cannot believe that there is no solution to it since the >>>> "tags_demo" application shows that it is indeed possible. >>>> :-/ >> that makes the two of us! I didn't get that when using tags_demo, >> you're not seeing the carrier that you use tags_demo; as far as I >> understood, your application does exactly the same, sending bursts >> with sob/eob tags? > > That's right. tags_demo works perfectly. No carrier in between the > bursts. The flow graph I posted before sends exactly one burst with > SOB and EOB tags. The only difference to tags_demo I could recognize > so far is that I don't assign time stamps to the samples. > But this shouldn't be a problem, should it? > > Frederik > > > _______________________________________________ Discuss-gnuradio > mailing list Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJURnbzAAoJEAFxB7BbsDrL2nEIAJnutUguHZy3qb0delF4EEoZ Wh+ikhML4LpzX76omgESTBzCIL+yeSzpwyF4+xFMs/laONrFoSYjKrIPicOUC85K pKbddIT1eYC4ulDLViEAK7G+f3h8d6fj8NvVlBOYflyz/z8kfT5Ow2P7vT2osPbi MrY9to3MQVGHriakq6mzf5cUe/F54YmscikEofrZXZj2EqwknULehS0Q0tm/Ms0L G+OamkGyPdsyxn8vmR2yMOScHSKxWF0yINYzf+jLJ4ypmbYUmn+99lsDZoyF9bJ3 L93I6IaRgUReawdYjvfSmDMOL1n0t1zyp9GBgBTly4JtfD2Rcvfn8al6FSzOZv8= =V3EN -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio