Forum: GNU Radio Simultaneous wireless transmission and reception between USRP2s

Dear GNU Radio list's members,

I have a set of USRP2+XCVR2450 with the host computers configured with
the *GNU Radio classic drivers* (v.3.3.0).

My main idea is to transmit and receive data through a wireless
connection between the USRP2s. For now, I'm unaware of the PHY
technology but the only restriction I have is that the transmission and
reception of each node has to be carried out in a single USRP2.

GNU Radio by default provides a set of examples but, as far as I know,
*tunnel.py* (in gnuradio-examples/digital folder) is the only script
that meets such condition.

I would like to ask whether you know the existence any other
implementation that executes both the transmission and reception
procedure in the same USRP2s.

Thank you in advance for your time. Any hint would be appreciated.

Regards,
J.R.

> GNU Radio by default provides a set of examples but, as far as I know,
> J.R.
>
>
> _______________________________________________
You should be aware that the XCVR2450 is a *half duplex*
daughtercard--the hardware is physically incapable of receiving and
   transmitting *at the same time*, although it's perfectly capable of
half-duplex operations, which can certainly happen on a single
   USRP2 with suitable Gnu Radio flow-graph behind it.




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

I'm also interested in this problem. Juan Ramon, did you make any 
progress?
If you did, would you mind sharing it?

For Marcus, I have a more general question regarding the flow graph. If 
I
have in my GRC both a UHD sink and a UHD source block, is it true that 
the
USRP2 will stay in receive mode until there're samples on the transmit
buffer? Will it then switch to transmit mode and transmit until the 
transmit
buffer is empty and switch back to receive mode?

Thanks,
Johnny

On 14/10/2011 10:04 AM, Tuan (Johnny) Ta wrote:
> Johnny
>
Basically, yes.  The UHD interface will turn back to receive when the
End-of-Burst is triggered.  But Josh probably has better details.
   I'm largely a receive-only guy in my own personal projects.

I'm also interested in this problem.

I have tried to setup a UHD sink and a UHD source using one USRP2 +
XCVR2450 daughterboard like tunnel.py. The flowgraph is like this: (1) 
Tx
Path: self.connect(self.txpath, self.sink); (2) Rx Path:
self.connect(self.source, self.rxpath). It works but makes my confused
since XCVR2450 does not support full-duplex operation, attempting to
operate in full-duplex will result in transmit-only operation. How is it
possible to setup a UHD sink and source at the same time with only one
USRP2 + XCVR2450? Does it mean the UHD driver can switch between tx and 
rx
states automatically? Or does it mean the UHD + 2450 is actually in tx 
mode?

Any idea would be appreciated. Thanks.


Regards,
Lizhao




2011/10/14 Marcus D. Leech <mleech@ripnet.com>

On 02/04/2012 04:29 AM, You Lizhao wrote:
> states automatically? Or does it mean the UHD + 2450 is actually in tx mode?
>
> Any idea would be appreciated. Thanks.
>


In the case of XCVR2450, the transmit state takes over when you are
using it in full duplex. Imagine an application that is always
receiving. When you transmit, the receiver is temporarily unavailable.

You can also use tags to precisely control the timing of samples:
http://gnuradio.org/cgit/gnuradio.git/tree/gr-uhd/include/gr_uhd_usrp_sink.h#n52

-Josh