Hello together, I am trying to transmit one complex cosine from both TX - Antenna of my USRP-x310 with two UBX-160 Daugtherboards. I am transmitting a cosine with the frequency of 100 kHz and the center frequency of my RFNoC Radio Blocks is 2.45 GHz. So basically I see a peak at 2.45 Ghz + 100 kHz at my spectrum analyzer (plus the lo leakage at 2.45 GHz). Additionally I receive the spectrum on another x310.
In the following link you can see my flowgraph in GRC: https://ibb.co/7W6mTKf As you can see i have two multiply blocks to change the phase of the complex cosines, the value of the multiply blocks are > pow(math.e, 1j*phi*(math.pi/180)) and > pow(math.e, 1j*psi*(math.pi/180)). I can change phi and psi with a qt gui range slider. Default value ist multiplication by 1. My goal with this setup was to check the MIMO capabilities of the USRP x310. I calculated the Phase offset both transmitted waves should have at the antenna of my spectrum analyzer. With my multiplication blocks I created different phase offsets, thus causing destructive interference at the receiving end (peak at analyzer is the smallest at this phase). However most of the time when I start different runs of my flowgraph (or when I power cycle the device) I always have to set a different phase offset to see the destructive interference. To me it seems pretty random which phase offset both transmitting path get even though i don't understand why. In another thread I read that maybe timed tuning will work for me but I did not quite understand what that improves in particular nor who I use it in my GRC generated python file. (Using the RFnoC Radio Blocks does not make it easier by the way.) This is the link: http://ettus.80997.x6.nabble.com/USRP-users-use-a-usrp-x310-as-MIMO-transmitter-daughterboard-synchronization-tt11642.html Any ideas, suggestions and explanations on how to phase align the transmit path of my (single) USRP x310 would be greatly appreciated! Best regards Felix _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
