On Thu, Mar 4, 2010 at 12:37, <[email protected]> wrote: > I have only one USRP2 and would like to use a loop-back cable to connect the > output to the input of the same USRP. So I would, for example, run > benchmark_tx and benchmark_rx in two different shells. Can I do it without > any worry ? I am asking the question because it seems that many people always > ran a such test with two USRP (one for Tx and the second for Rx).
No. In general, USRP applications assume they "own" the USRP they are communicating with, so the second script you run will stomp on the first one. There is no problem, however, using a single machine and having two USRP1 devices on the USB. In this case, scripts can distinguish which USRP they are talking to using a parameter during initialization. Not all example scripts are written with this in mind; I'd have to check if the digital example you reference does so (I think so.) A single USRP, however, could be used with a loopback between TX and RX if you were to write your own script that pulled in the "transmit_path" and "receive_path" hierarchical blocks into a single application, similar to what tunnel.py does. As an aside, I think the recommendation is to use 30 dB of attenuation between the transmitter and receiver boards to avoid damaging the front end of the receiver. You may be able to get away with less attenuation if you know what you are doing, and properly control the transmit power. Johnathan _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
