Re: [Discuss-gnuradio] Simultaneous wireless transmission and reception between USRP2s

[Josh Blum]

On 02/04/2012 04:29 AM, You Lizhao wrote:
> 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.
> 


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