Re: [Discuss-gnuradio] Parallel transmission and reception....

[Michael Dickens]

Hi Ali - I think if you search the GNU Radio discussion list you'll  
find some references similar to what you want to do.  As a quick  
reply:  If you want to monitor the channel using the same Tx/Rx  
antenna and Flex board, then you have 2 choices:

(1) Do simultaneous Tx and Rx: You'll need to setup a "feedback" loop  
in GNU Radio that cancels the Tx signal from the Rx signal, in order  
to actively monitor the Rx signal.  There are 2 primary issues with  
this method:

 (a) best receiver sensitivity you'll get is maybe 30 dB off of what  
the USRP is capable -- so, maybe 50 dB dynamic range if you're really  
lucky, and probably less.  Meaning: a "weak" signal (but, one which  
would normally be detectable) will be masked and be undetectable due  
to the signal processing and other losses in this system (software and  
hardware based losses).  If that's OK, then there's the other issue:

 (b) GNU Radio doesn't do feedback loops of this sort -- someone  
correct me if I'm wrong.

(2) switch between Tx and Rx, but not do both simultaneously.  There  
is significant ongoing work in this field.

Good luck. - MLD

On May 2, 2010, at 8:26 AM, Muhammad Ali Khan wrote:
> I am using Flex900 daughter board with USRP board. I am using TX/RX  
> port for the transmission and for channel sensing, is it possible to  
> do reception process simultaneously so that i can receive what i am  
> transmitting.... Please help me this, and If not then give me a good  
> reason that what are the factors creating hurdles in this.