Agreed with Ron. Remove one of the 30dB pads and play around with the gain on the RX side to dial things in.
You could also run a simple example of transmitting and receiving a CW between the boards. If you're not sharing a 10 MHz reference between the two, you might find that there is a slight frequency offset between the boards that you need to compensate for. e.g. TX a CW at 1GHz using the UHD example tx_waveforms, and receive that in with uhd_fft.grc (or rx_ascii_art_dft - https://kb.ettus.com/Verifying_the_Operation_of_the_USRP_Using_UHD_and_GNU_Radio#Terminal_DFT.2FFFT). If there's any kind of frequency offset between the two, you'll see it on the RX side and you can either add in a frequency offset or introduce a shared reference clock to compensate for it. -Sam On Fri, Jun 12, 2020 at 4:50 PM Ron Economos via USRP-users < [email protected]> wrote: > 60 dB is a lot of attenuation. You can remove *one* of the 30 dB > attenuators. For gain settings, 30 is good for RX and 50 to 60 is good for > TX. > > Ron > On 6/12/20 14:14, Thuc TheGifted via USRP-users wrote: > > Hi everyone, > > I am new to this USRP B200 board. I currently have two boards and I want > to connect the Tx port of one board to the Rx port of another using a SMA > cable to visualize the communication. > > So I start with something available online here > > https://www.mathworks.com/help/supportpkg/usrpradio/examples/qpsk-transmitter-with-usrp-r-hardware.html > > and > > https://www.mathworks.com/help/supportpkg/usrpradio/examples/qpsk-receiver-with-usrp-r-hardware.html > > > Basically, my hardware connection is > Computer_1 + B200_1(Tx port) + 30 dB attenuator + SMA cable + 30 dB > attenuator + B200_2(Rx port) + Computer_2 > > And I run the transmitter code on the computer_1 and run the receiver code > on the computer_2. The transmitter light and the receiver light both turns > on, so I think they are doing something. > > However the result I get on my receiver end on computer_2 is not good. > They just look like noise. > > I think because I use a different kind of board, so I need to modify the > gain parameters in the code. But I have no idea about how to make it > correctly. > > I hope someone with more experience with this board can show me how to do > it right. > Could you please help me on this. > Thank you. > > -Ves > > _______________________________________________ > USRP-users mailing > [email protected]http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > _______________________________________________ > USRP-users mailing list > [email protected] > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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