Re: [Discuss-gnuradio] Transmitting bursts with GRC by inserting SOB and EOB

[Marcus Müller]

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Gooood question.
The corresponding lines look something like [1] (while iterating over
the tags in the current set of items):

 BOOST_FOREACH(const tag_t &my_tag, _tags) {
...
 else if(pmt::is_null(_length_tag_key)
                && pmt::equal(key, SOB_KEY)) {
        if (my_tag.offset != samp0_count) {
                max_count = my_tag_count;
                break;
        }
        // Bursty tx will not use time specs, unless a tx_time tag is also 
given.
        _metadata.has_time_spec = false; //(wut)
        _metadata.start_of_burst = pmt::to_bool(value);
        }


... 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?

Cheers,
Marcus

[1]
https://github.com/gnuradio/gnuradio/blob/master/gr-uhd/lib/usrp_sink_impl.cc#L659

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 address@hidden 
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
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