Simultaneous transmit/receive not using antennas?


Using USRP and FLEX900 daughterboards:

During simultaneous transmit/receive it seems the ‘receive’ data sent to
the computer, is just a copy of the ‘transmit’ data sent to the FPGA,
and is not actually being sampled from the receive antenna, since
disconnecting either the transmit/receive antenna doesn’t affect the
signal shown in the usrp_oscope display.

I opened two terminal windows and ran usrp_oscope in one and usrp_siggen
in another, and specified either:

  •      Side A and Side B with two daughterboards in one USRP, or
  •      USRP 0 and USRP 1 with two USRPs connected to one computer.

I also used GRC to write a flow graph to access the TX/RX and RX2 ports
on one daughterboard.

When I connect two USRPs to different computers and then disconnect
either antenna, the signal shown in the usrp_oscope display of the
‘receive’ data, i.e., reduces amplitude from +/- 16KHz to +/- 800Hz.

This what I’d expect from simultaneous transmit/receive using one USRP
or computer, is that expected when using usrp_siggen and usrp_oscope?

Leo Kimminau