The following figure shows a simplified block diagram of the NI USRP-2942R. The signal path is duplicated for each of the two channels.
The area within the dotted line indicates the processing on the FPGA when you use NI-USRP with the default FPGA image. When you use LabVIEW FPGA, you control the processing on the FPGA.
The RF switch allows transmit and receive operations to occur on the same shared antenna. On the NI USRP-2942R, one antenna is designated receive-only.