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List: gnuradio-discuss
Subject: Re: [Discuss-gnuradio] Burst Tagger block - What I'm I doing wrong?
From: Tom Rondeau <tom () trondeau ! com>
Date: 2015-04-29 14:35:52
Message-ID: CA+SzT6hfi-EisDR3qjKmMMeJ4X5tT_C+OTpRxOHePSWnt4tGhQ () mail ! gmail ! com
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On Thu, Apr 16, 2015 at 12:05 PM, Nicolas Cuervo Benavides <
cuervonicolas@gmail.com> wrote:
> Hi all!
>
> Im trying to implement a system that should change it's normal functioning
> when another system with higher priority comes into play. For that, we have
> thought of two ways: changing the central frequency of our system of
> interest and/or stopping the sending process automaticaly.
>
> Im in charge of the latter, and for that I've found that maybe the "burst
> tagger" block could be of use. As far as I have understood, that block adds
> SOB and EOB tags to the element that I'm about to send, and those are then
> understood in the UHD as metadata. Afterwards (and may be here is where I
> get a little bit confused or have the misconception of its functionality),
> 'if the UHD receives an EOB tag, it turns of the transmitter until a new
> SOB comes'. (I would also like to know if the part in between the single
> quotation marks is also right. I've checked the code for UHD sink and I
> still dont have this part 100% clear).
>
> Now, comes my main question and the reason why I think Im getting the
> concept wrong: I apply a signal (sinus) at the first port of the burst
> tagger and on the second I apply what would be my detection of the other
> system. In order to see if the tags come or not, I connect at the output of
> the block a "Tag debug", where I do can see that it is a 'False' tag when
> the trigger is <=0 and 'true' when it is >0. However, I still see the
> signal being sent through the USRP.
>
> I dont know if the sinus signal is not suitable for this test experiment,
> or if actually the burst tagger does not do what I understood. If someone
> has a clearifying opinion or remark I would really appreciate it. I've
> checked some previous questions here in feeder and the example explanation
> was implemented as I did. Any comment will be highy welcomed.
>
> Thank you in advance.
>
> Regards,
>
> Nicolas
>
I think the issue is related to the fact that the gr-uhd and that
burst_tagger weren't designed together. In fact, the burst tagger block
came before the UHD blocks handled tags and there wasn't any coordination.
First, place a tag_debug block in the flowgraph after the burst_tagger.
That will make sure that the burst_tagger is actually properly tagging
bursts.
But the main problem is that the burst_tagger produces tags with the key
"burst" and the value true or false. You'll need to edit this block to
change it to using "tx_sob" for the start of burst and "tx_eob" for the
end. That should get you closer to what you want.
Tom
[Attachment #5 (text/html)]
<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Thu, Apr 16, 2015 \
at 12:05 PM, Nicolas Cuervo Benavides <span dir="ltr"><<a \
href="mailto:cuervonicolas@gmail.com" \
target="_blank">cuervonicolas@gmail.com</a>></span> wrote:<br><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"><div dir="ltr">Hi all!<div><br></div><div>Im trying to \
implement a system that should change it's normal functioning when another system \
with higher priority comes into play. For that, we have thought of two ways: changing \
the central frequency of our system of interest and/or stopping the sending process \
automaticaly.</div><div><br></div><div>Im in charge of the latter, and for that \
I've found that maybe the "burst tagger" block could be of use. As far \
as I have understood, that block adds SOB and EOB tags to the element that I'm \
about to send, and those are then understood in the UHD as metadata. Afterwards (and \
may be here is where I get a little bit confused or have the misconception of its \
functionality), 'if the UHD receives an EOB tag, it turns of the transmitter \
until a new SOB comes'. (I would also like to know if the part in between the \
single quotation marks is also right. I've checked the code for UHD sink and I \
still dont have this part 100% clear).</div><div><br></div><div>Now, comes my main \
question and the reason why I think Im getting the concept wrong: I apply a signal \
(sinus) at the first port of the burst tagger and on the second I apply what would be \
my detection of the other system. In order to see if the tags come or not, I connect \
at the output of the block a "Tag debug", where I do can see that it is a \
'False' tag when the trigger is <=0 and 'true' when it is >0. \
However, I still see the signal being sent through the \
USRP.</div><div><br></div><div>I dont know if the sinus signal is not suitable for \
this test experiment, or if actually the burst tagger does not do what I understood. \
If someone has a clearifying opinion or remark I would really appreciate it. I've \
checked some previous questions here in feeder and the example explanation was \
implemented as I did. Any comment will be highy \
welcomed.</div><div><br></div><div>Thank you in \
advance.</div><div><br></div><div>Regards,</div><div><br></div><div>Nicolas \
</div></div> </blockquote></div><br></div><div class="gmail_extra">I think the issue \
is related to the fact that the gr-uhd and that burst_tagger weren't designed \
together. In fact, the burst tagger block came before the UHD blocks handled tags and \
there wasn't any coordination.</div><div class="gmail_extra"><br></div><div \
class="gmail_extra">First, place a tag_debug block in the flowgraph after the \
burst_tagger. That will make sure that the burst_tagger is actually properly tagging \
bursts.</div><div class="gmail_extra"><br></div><div class="gmail_extra">But the main \
problem is that the burst_tagger produces tags with the key "burst" and the \
value true or false. You'll need to edit this block to change it to using \
"tx_sob" for the start of burst and "tx_eob" for the end. That \
should get you closer to what you want.</div><div class="gmail_extra"><br></div><div \
class="gmail_extra">Tom</div><div class="gmail_extra"><br></div></div>
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