Can an USRP 2900 send data with one antenna and receive it with the other antenna ?

[Joram_FC]

Hello everyone,

I want to send a carrier wave with the TX1 antenna and sweep through the frequency spectrum while receiving at the same time this carrier wave on the RX2 antenna. Is it possible using the USRP 2900 ?

Thanks for your help,

Joram

[vvkakade]

Hi Joram_FC,

Yes this is possible.

If you are using the USRP 2900 with LabVIEW and NI-USRP you can try running the niUSRP EX Rx Continuous Async.vi and niUSRP EX Tx Continuous Async.vi example VIs side by side.

[Joram_FC]

Thank you for the answer,

The thing is that it is quite simple to send and receive data through the antennas with a fixed frequency. But it is way harder when trying to make it sweep through frequencies.

For example : Starting at 2.4GHz, sending on one antenna and receiving it with the other, then changing the frequency to 2.401GHz and starting over.

I'm using two VIs side by side but I can't understand how the USRP reacts when I'm changing the carrier frequency in the two different VIs. Because I can change the carrier frequency on one VI but when I read the properties on the other VI the carrier hasn't change (despite the fact that they act on the same USRP 2900).

I'm a bit lost here.

Thanks !

[psisterhen]

The Rx and Tx LOs are independent and separately tune-able.  So changing one doesn't affect the other.

[Joram_FC]

Are you sure ? Because it always seems to me that the 2900 only had one LO. Here is the block diagram :

 

Maybe the carrier frequency can slightly change via the DSP frequency : http://zone.ni.com/reference/en-XX/help/373380G-01/usrppropref/pniusrp_lofrequency/

I don't know can you confirm ?

Thanks.

[psisterhen]

The LOs share a common reference (that's the block in the lower left- either an external or internal 10 MHz signal).  So they can be frequency locked.  However, they are separate synthesizers which can be tuned independently.  Those are the blocks you see connected to the mixers.