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How to turn-off TX of UHD sink in gnuradio companion?

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How to turn-off TX of UHD sink in gnuradio companion?

mlustig
Hi --

I just got my USRP B200. I'm able to receive and transmit with it. It is very nice!
I have one issue. In gnuradio-companion I pipe an FM modulated signal into UHD sink with the TX/RX output.
I would like to have a button that turns the TX off to allow RX on the same port. I can not find a way to do that within gnuradio-companion. Anybody has an idea?

My workaround right now is to turn the transmit gain down, and change the center frequency of the transmit away while receiving in RX2 port. This is a "full duplex" mode, but I would really like a half-duplex on the RX/TX.

Thanks!

-- Miki
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Re: How to turn-off TX of UHD sink in gnuradio companion?

Tom Rondeau-2
On Wed, Dec 4, 2013 at 3:37 AM, mlustig <[hidden email]> wrote:

> Hi --
>
> I just got my USRP B200. I'm able to receive and transmit with it. It is
> very nice!
> I have one issue. In gnuradio-companion I pipe an FM modulated signal into
> UHD sink with the TX/RX output.
> I would like to have a button that turns the TX off to allow RX on the same
> port. I can not find a way to do that within gnuradio-companion. Anybody has
> an idea?
>
> My workaround right now is to turn the transmit gain down, and change the
> center frequency of the transmit away while receiving in RX2 port. This is a
> "full duplex" mode, but I would really like a half-duplex on the RX/TX.
>
> Thanks!
>
> -- Miki

One easy way is to use the mute block and have it controllable from a
check box GUI element.

Tom

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Re: How to turn-off TX of UHD sink in gnuradio companion?

Marcus D. Leech
On 12/04/2013 09:46 AM, Tom Rondeau wrote:
>
> One easy way is to use the mute block and have it controllable from a
> check box GUI element.
>
> Tom
>
Unless the mute block causes an EOB tag to be sent downstream to the UHD
sink, that won't have the desired effect.

When doing half-duplex, sharing a common RF port, the USRP needs to know
when you've ended a "burst", so that it can
   switch the antenna port between the RX and TX.  And again when you
start transmitting, it'll need a SOB tag to cause
   the TX state machine to wake-up.

The usual mode implemented by gr-uhd is continuous streaming on TX.




--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org


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Re: How to turn-off TX of UHD sink in gnuradio companion?

mlustig
I see,....interesting.

So how do you send an SOB tag within gnu radio companion?
I'm new to this and could not find any documentation on grc that made sense to me.

-- Miki, KK6MRI, from mobile



> On Dec 4, 2013, at 6:51 AM, "Marcus D. Leech" <[hidden email]> wrote:
>
>> On 12/04/2013 09:46 AM, Tom Rondeau wrote:
>>
>> One easy way is to use the mute block and have it controllable from a
>> check box GUI element.
>>
>> Tom
> Unless the mute block causes an EOB tag to be sent downstream to the UHD sink, that won't have the desired effect.
>
> When doing half-duplex, sharing a common RF port, the USRP needs to know when you've ended a "burst", so that it can
>  switch the antenna port between the RX and TX.  And again when you start transmitting, it'll need a SOB tag to cause
>  the TX state machine to wake-up.
>
> The usual mode implemented by gr-uhd is continuous streaming on TX.
>
>
>
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> [hidden email]
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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Re: How to turn-off TX of UHD sink in gnuradio companion?

Marcus D. Leech
On 12/04/2013 10:49 AM, Michael Lustig wrote:
> I see,....interesting.
>
> So how do you send an SOB tag within gnu radio companion?
> I'm new to this and could not find any documentation on grc that made sense to me.
>
> -- Miki, KK6MRI, from mobile
There's a burst-tagger block:

http://gnuradio.org/doc/doxygen/classgr_1_1blocks_1_1burst__tagger.html

I can't for the life of me remember how to form the SOB/EOB tags that
UHD needs.  But perhaps someone who has actually used the EOB/SOB stuff
   could chime in.



--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org


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Re: How to turn-off TX of UHD sink in gnuradio companion?

mlustig
I tried the Burst Tagger block. Reading on-line it seems that the key tags should be tx_eob and tx_sob

I implemented this way:

I can see the Tags in the stream using Tag debugger, but nothing is happening to the UHD sink which keeps transmitting. 

Anybody? 

Thanks,


-- Miki



On Dec 4, 2013, at 8:04 AM, Marcus D. Leech [via GnuRadio] <[hidden email]> wrote:

On 12/04/2013 10:49 AM, Michael Lustig wrote:
> I see,....interesting.
>
> So how do you send an SOB tag within gnu radio companion?
> I'm new to this and could not find any documentation on grc that made sense to me.
>
> -- Miki, KK6MRI, from mobile
There's a burst-tagger block:

http://gnuradio.org/doc/doxygen/classgr_1_1blocks_1_1burst__tagger.html

I can't for the life of me remember how to form the SOB/EOB tags that
UHD needs.  But perhaps someone who has actually used the EOB/SOB stuff
   could chime in.



--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org


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